# Patent

## Title
Mammalian cancer cell and transgenic mammal carrying human protooncogene and kit for diagnosing cancer using said protooncogene

## Abstract

The present invention provides a mammalian cell transfected with an expression vector comprising a human protooncogene which has the nucleotide sequence of SEQ ID NO: 1; a mammalian embryo carrying a nucleic acid construct comprising the human protooncogene; a transgenic cancer mammal, which is derived from the mammalian embryo; and a kit for diagnosing a cancer selected from the group consisting of breast, kidney, ovary and stomach cancers, which comprises a probe having the nucleotide sequence complementary to mRNA transcribed from the human protooncogene or a portion of the mRNA; or an antibody binding specifically to a protein translated from the mRNA or a portion of the protein.

## Background
FIELD OF THE INVENTION 
The present invention relates to a mammalian cancer cell transformed with an expression vector comprising a human protooncogene having the nucleotide sequence of SEQ ID NO: 1; a mammalian embryo comprising a nucleic acid construct containing the protooncogene; a transgenic cancered mammal derived from the mammalian embryo; and a kit for diagnosing breast, kidney, ovary or stomach cancer using the protooncogene.
BACKGROUND OF THE INVENTION 
Higher animals including man each carry approximately 100,000 genes, but only about 15% thereof is expressed, and characteristics of individual's biological process, e.g., genesis, differentiation, homeostasis, responses to stimuli, control of cell cycle, aging and apoptosis (programmed cell death), are determined depending on which genes are expressed (Liang, P. and A. B. Pardee, Science, 257: 967-971 (1992)).
Pathogenic phenomena such as tumorigenesis are caused by gene mutation which brings about changes in the mode of gene expression.
It has been reported that tumorigenesis is caused by various genetic changes such as the loss of chromosomal heterozygosity, activation of oncogenes and inactivation of tumor suppressor genes, e.g., p53 gene (Bishop, J. M., Cell, 64, 235-248 (1991); and Hunter, T., Cell, 64, 249-270 (1991)). Further, it has been reported that 10 to 30% of human cancer arises from the activation of oncogene through amplification of protooncogenes.
Therefore, the activation of protooncogenes plays an important role in the etiology of many tumors and there has existed a need to identify protooncogenes.
The present inventor reported that a protooncogene, human cervical cancer 1 (HCCR-1), is specifically overexpressed in cancer cells (Korean Patent Laid-open Publication No. 2001-39566). In order to unravel the mechanism involved in the tumorigenesis, the present inventor has endeavored to prepare a cancer cell line and a transgenic mammal developing cancer using HCCR-1 protooncogene.
SUMMARY OF THE INVENTION 
Accordingly, it is an object of the present invention to provide a mammalian cell having introduced HCCR-1 protooncogene.
Another object of the present invention is to provide a mammalian embryo carrying HCCR-1 protooncogene, and a transgenic mammal derived from the mammalian embryo.
A further object of the present invention is to provide a kit for diagnosing breast, kidney, ovary or stomach cancer using HCCR-1 protooncogene.
In accordance with one aspect of the present invention, there is provided a mammalian cell transformed with an expression vector comprising human protooncogene HCCR-1 which has the nucleotide sequence of SEQ ID NO: 1.



BRIEF DESCRIPTION OF THE DRAWINGS
The above objects and features of the present invention will become apparent from the following description of preferred embodiments taken in conjunction with the accompanying drawings, in which:
FIGS. 1A and 1B are the respective phase-contrast features of monolayer-cultured HCCR-1M and parental wild-type NIH/3T3 cells;
FIG. 2 is the hematoxylin-eosin staining result of monolayer-cultured HCCR-1M cells;
FIG. 3 is a transmission electron microscope picture of HCCR-1M cells;
FIG. 4 is a photograph of the nude mouse allografted with HCCR-1M cells showing the palpable tumor nodule;
FIG. 5 is the hematoxylin-eosin staining result of the palpable tumor nodules taken from the nude mouse allografted with HCCR-1M cells;
FIG. 6 is a transmission electron microscope picture of the palpable tumor nodules taken from the nude mouse allografted with HCCR-1M cells;
FIGS. 7A to 7D are the immunohistochemical analysis results showing the expression of reticulin fibers, keratin, epithelial membrane antigen and vimentin, respectively, in the palpable tumor nodules taken from the nude mouse allografted with HCCR-1M cells;
FIG. 8 is a phase-contrast feature of monolayer-cultured HCCR-1MN cells;
FIG. 9 is the western blot analysis result showing the expression of HCCR-1 protooncogene in HCCR-1M and HCCR-1MN cells;
FIGS. 10A and 10B are the phase-contrast features of monolayer-cultured HCCR-1H and parental wild-type 293 cells, respectively;
FIG. 11 is the hematoxylin-eosin staining result of the palpable tumor nodules taken from the nude mouse xenografted with HCCR-1H cells;
FIGS. 12A to 12C are the immunohistochemical analysis results showing the expression of cytokeratin 8, cytokeratin 19 and vimentin, respectively, in the palpable tumor nodules taken from the nude mouse xenografted with HCCR-1H cells;
FIG. 13 is the northern blot analysis result showing the expression of HCCR-1 protooncogene in HCCR-1H cells;
FIG. 14 is a graph showing protein kinase C activities of parental wild-type NIH/3T3 cell, comparative NIH/3T3 cell transfected with vector pcDNA3 and HCCR-1M cell;
FIG. 15 is a graph showing telomerase activities of positive control 293 cell, negative control cell, parental wild-type NIH/3T3 cell, comparative NIH/3T3 cell transfected with vector pcDNA3 and HCCR-1M cells;
FIGS. 16A to 16C are the northern blot analysis results showing the expression of egr-1, c-fos and glyceraldehyde-2-phosphate dehydrogenase (GAPDH) genes, respectively, in HCCR-1M cell;
FIG. 17A is the western blot analysis result showing the expression of p53 tumor suppressor gene in HCCR-1H cell; and FIG. 17B, β-actin of the same blot;
FIG. 18 is the immunoprecipitation result showing the expression of p53 tumor suppressor in HCCR-1H cell;
FIGS. 19A, 19C, 19E, 19G and 19I are the western blot analysis results showing the expression of MDM2, Bax, p21WAF1, p16INK4A and p14ARF genes, respectively, in HCCR-1H cell; and FIGS. 19B, 19D, 19F, 19H and 19J, β-actin in each of the above blots;
FIG. 20A is the western blot analysis result showing GST protein in the precipitate prepared by immunoprecipitating the FLAG protein of the CHO cell cotransfected with the vector expressing the fusion protein of FLAG and HCCR-1 and the vector expressing the fusion protein of GST and D52; and FIG. 20B, PLAG protein in the precipitate prepared by immunoprecipitating the GST protein;
FIG. 21 is a schematic diagram of the nucleic acid construct containing HCCR-1 protooncogene;
FIG. 22 is a transgenic cancered mouse derived from an embryo having introduced HCCR-1 protooncogene;
FIG. 23 is a photograph of breast tumor of the transgenic mouse derived from the embryo carrying introduced HCCR-1 protooncogene;
FIG. 24 is the hematoxylin-eosin staining result of the breast tumor taken from a transgenic mouse derived from the embryo carrying introduced HCCR-1 protooncogene;
FIG. 25 is a transmission electron microscope picture of the breast tumor taken from the transgenic mouse derived from the embryo carrying introduced HCCR-1 protooncogene;
FIG. 26A is the northern blot analysis result showing the expression of HCCR-1 protooncogene in breast, kidney, ovary and stomach tumor tissues; and FIG. 26B, the same blot hybridized with β-actin probe;
FIG. 27 is the western blot analysis result showing the expression of HCCR-1 protooncogene in human breast, kidney, ovary and stomach tumor tissues; and
FIG. 28 is the fluorescence in situ hybridization analysis result showing the position of HCCR-1 protooncogene on the human chromosome.



DETAILED DESCRIPTION OF THE INVENTION 
The human protooncogene (hereinafter “HCCR-1 protooncogene”) of SEQ ID NO: 1 which is used in the preparation of the inventive mammalian cell and transgenic mammal is located on the long arm (12q) of the 12th chromosome and has an open reading frame which encodes a protein having the amino acid sequence of SEQ ID NO: 2 and molecular weight of about 50 kDa.
In consideration of the degeneracies of codons and the preferred codons in a specific animal wherein the HCCR-1 protooncogene is to be expressed, various changes and modifications of the nucleotide sequence of SEQ ID NO:1 may be made, e.g., in the coding region thereof without adversely altering the amino acid sequence of the expressed protein, or in the non-coding region without adversely affecting the expression of the HCCR-1 protooncogene. Therefore, the present invention also includes, in its scope, a polynucleotide having substantially the same base sequence as the HCCR-1 protooncogene, and a fragment thereof. As used herein, “substantially the same polynucleotide” refers to a polynucleotide whose base sequence shows 80% or more, preferably 90% or more, most preferably 95% or more homology to the HCCR-1 protooncogene.
The HCCR-1 protooncogene can be obtained from human cancer tissues or synthesized using a conventional DNA synthesis method. Further, the HCCR-1 protooncogene thus prepared may be inserted to a conventional vector to obtain an expression vector.
The expression vector may, in turn, be introduced into a suitable mammalian cell to obtain a mammalian cell transfected with the expression vector. For example, NIH/3T3 cells (ATCC CRL 1658), a differentiated mouse fibroblast cell line, and 293 cells (ATCC CRL 1573), a human embryonic kidney cell line, were transfected with expression vector pcDNA3/HCCR-1 containing the HCCR-1 protooncogene to obtain the NIH/3T3 and 293 cells transfected with HCCR-1 protooncogene, designated HCCR-1M and HCCR-1H cells, respectively, which were deposited with Korean Collection for Type Cultures (KCTC) (Address: #52, Oun-dong, Yusong-ku, Taejon 305-333, Republic of Korea) on Dec. 26, 2000 under the accession numbers of KCTC 0923BP and KCTC 0922BP, respectively, in accordance with the terms of Budapest Treaty on the International Recognition of the Deposit of Microorganism for the Purpose of Patent Procedure.
The inventive mammalian cell thus obtained overexpresses HCCR-1 protooncogene and exhibits morphological characteristics of tumor giant cells. Specially, mouse cell HCCR-1M has a polygonal shape, lobulated nucleus with prominent nucleoli, well developed rough endoplasmic reticula (rER) and Golgi complexes, and microvilli on the cell surface, and exhibits atypical mitotic figures. The human cell HCCR-1H has increased cell dimension and cellularity compared with the wild-type cell.
The inventive mammalian cell has a tumorigenicity and therefore a mammal grafted with the inventive mammalian cell develops a tumor, e.g., palpable tumor. Further, a mammalian cell isolated from the tumor has a tumorigenicity. For example, a mouse cell, designated HCCR-1MN, isolated from a palpable tumor of a nude mouse grafted with HCCR-1M cell has the morphological features similar with those of HCCR-1M cell.
The inventive mammalian cell produces a large amount of HCCR-1 protein which interacts with D52 protein (GenBank accession number NM003288) which has been reported to be associated with breast carcinoma (Byrne, J. A., et al., Cancer Res., 55, 2896-2903 (1995); and Byrne, J. A., et al., Oncogene, 16, 873-881 (1998)). It also enhances a cellular protein kinase C (PKC) and telomerase activities, induces the loss of particular cell cycle checkpoint controls, and suppresses the egr-1 expression, thereby predisposing cells to malignant conversion. In this process, the expression of p53 tumor suppressor gene involved in the cell cycle control increases while most of the p53 proteins are inactivated, thereby leading to malignant conversion. The HCCR-1 protooncogene induces functional inactivation of p53 tumor suppressor at an upstream level. Therefore, if a portion of HCCR-1 protooncogene which regulates p53 gene is identified, the p53 activity may be recovered by changing the corresponding nucleotide sequence.
Further, a nucleic acid construct comprising HCCR-1 protooncogene may be introduced into a suitable embryo of a mammal, e.g., a mouse, and the mammalian embryo thus obtained may be implanted in the uterus of a suitable recipient and allowed to develop to term to obtain a transgenic mammal. The method for preparing a transgenic mammal is well known in the art, and it is preferable to introduce the nucleic acid construct into an embryo at the 8-cell stage or earlier.
The transgenic mammal thus prepared overexpresses HCCR-1 protooncogene and develops ductal papillary adenocarcinoma of breast exhibiting the charachteristic features of: well-circumscribed nodule without capsule; papillary structures and glandular or duck-like structures; extensive necrosis occurring in the central portion; cuboid or ovoid cells having indistinct borders; normal breast tissues being adjacent thereto; and a significant amount of granular, eosinophilic cytoplasm.
A transgenic embryo may be obtained by mating male and female transgenic mammals. An exemplary transgenic embryo is mouse FVB/N embryo (designated mouse embryo HCCR-1) carrying the nucleic acid construct having the structure of FIG. 21, which was deposited with the Korean Collection for Type Cultures (KCTC) (Address: #52, Oun-dong, Yusong-ku, Taejon 305-333, Republic of Korea) on Dec. 26, 2000 under the accession number of KCTC 0924BP, in accordance with the terms of Budapest Treaty on the International Recognition of the Deposit of Microorganism for the Purpose of Patent Procedure.
Since the inventive mammalian cell and transgenic mammal overexpresses HCCR-1 protooncogene to develop cancer, they are advantageously used in screening a carcinogen or anti-cancer agent, e.g., antioxidant.
Further, HCCR-1 protooncogene is overexpressed in breast, kidney, ovary and stomach cancers, and therefore, the product thereof may be effectively used in diagnosing the cancers. The cancer diagnosis may be conducted by reacting mRNA or a protein sample taken from breast, kidney, ovary or stomach tissue of a subject with a probe or antibody which specifically binds to mRNA or the protein expressed from the HCCR-1 protooncogene; and detecting the HCCR-1 mRNA or protein according to various methods known in the art, thereby determining whether the subject has overexpressed products of HCCR-1 protooncogene. The presence of the protooncogene product may be easily detected by labeling the probe or antibody with a radioisotope or an enzyme. Therefore, the present invention also provides a kit for diagnosing a breast, kidney, ovary or stomach cancer, which comprises a probe or an antibody which specifically binds to an mRNA or protein expressed from HCCR-1 protooncogene. Exemplary probes include a polynucleotide or oligonucleotide which has a nucleotide sequence complementary to mRNA transcribed from the HCCR-1 protooncogene or a portion of the mRNA so that it specifically binds to the HCCR-1 mRNA, and preferred is that having the nucleotide sequence of SEQ ID NO: 3. The probe can be obtained from human tissues or synthesized using a conventional DNA synthesis method. Further, the antibody can be prepared according to conventional method kwon in the art.
The following Examples are intended to further illustrate the present invention without limiting its scope.
REFERENCE EXAMPLE 1
Transmission Electron Microscopy (TEM)
Cells or tissues were fixed with 2.5% glutaraldehyde in a phosphate buffer (pH 7.4) and then postfixed with a 2% osmium tetroxide. Specimens were dehydrated in a graded series of ethanols and embedded in Epon 812. Ultrathin sections thereof were stained with uranyl acetate and lead citrate, and photographed by TEM (JEOL 1,200 EX, Tokyo, Japan).
REFERENCE EXAMPLE 2
Western Blot Analysis
Cells were harvested and lysed in a Laemmli sample buffer in accordance with the method described by Laemmli (Nature, 227, 680-685 (1970)). The cellular proteins were separated by 10% SDS-PAGE and then electroblotted onto nitrocellulose membranes. The membranes were incubated with the antibody. After washing, the membranes were incubated with a blocking solution containing 1:1,000 dilution of peroxidase-conjugated goat anti-rat immunoglobulin (Jackson ImmunoResearch) as a secondary antibody. Proteins were revealed by an ECL-Western blot detection kit (Amersham).
REFERENCE EXAMPLE 3
Immunohistochemical Analysis
Tissues were incubated with a primary antibody and then cut in a thickness of 5 μm. Binding of primary antibody was visualized by biotinylated secondary antibody, avidin, biotinylated horseradish peroxidase and AEC (aminoethyl carbazole) as the chromogen (HISTOSTAIN-BULK KITS, Zymed).
REFERENCE EXAMPLE 4
Isolation of Total RNA
Total RNAs were extracted from the tissue specimens or cells using a commercial system (RNeasy total RNA kit, Qiagen Inc., Germany), and DNA contaminants were removed therefrom using Message clean kit (GenHunter Corp., USA).
REFERENCE EXAMPLE 5
Northern Blot Analysis
20 μg of the total RNAs were electrophoresed through 1% formaldehyde agarose gel and transferred to nylon membranes (Boehringer-Mannheim, Germany). The blot was hybridized overnight at 42° C. with 32P-labeled random-primed probe which was prepared using a rediprime II random prime labeling system (Amersham, UK). The northern blot analysis results were consistently repeated two times, as quantified by densitometry and the same blot was hybridized with a β-actin probe to confirm mRNA integrity.
PREPARATION EXAMPLE 1
Construction of Expression Vector Containing HCCR-1 Protooncogene
E. coli JM-109/HCCR1 (KCTC 0667BP) has expression vector pCEV-LAC/HCCR-1 containing the full length HCCR-1 cDNA represented by the nucleotide sequence of SEQ ID NO: 1. E. coli JM-109/HCCR1 cells were cultured and expression vector pCEV-LAC/HCCR-1 was isolated therefrom. Expression vector pCEV-LAC/HCCR-1 thus obtained was cleaved with SalI to obtain a 2.1 kb DNA fragment containing the full length HCCR-1 cDNA.
Mammal expression vector pcDNA3 (Invitrogene) was cleaved with XhoI to make a compatible end with SalI. The 2.1 kb SalI fragment was ligated with the XhoI-digested pcDNA3 to obtain expression vector pcDNA3/HCCR-1 containing the full length HCCR-1 cDNA.
PREPARATION EXAMPLE 2
Production of Anti-HCCR-1 Antibody
In order to obtain HCCR-1 proteins useful in the preparation of anti-HCCR-1 antibody, E. coli JM-109/HCCR1 (KCTC 0667BP) cells were cultured and expression vector pCEV-LAC/HCCR-1 was isolated therefrom. Expression vector pCEV-LAC/HCCR-1 was subjected to polymerase chain reaction (PCR) using primers of SEQ ID Nos: 4 and 5 to amplify a DNA region from the 123rd to the 473rd nucleotides of SEQ ID NO: 1 (the 39th to the 155th amino acid residues of SEQ ID NO: 2). The PCR product thus obtained was inserted at BamHI/SalI sites of vector pMAL-p2 (New England Biolab, USA) to obtain a recombinant vector (designated pMAL-p2/HCR-1-c-terminal), and then, E. coli BL21 (ATCC CRL 47092) was transformed with recombinant vector pMAL-p2/HCCR-1-c-terminal. The transformant was cultured in LB media and the resulting culture was diluted with 100-fold volume of LB media. The diluted culture was incubated for 3 hours, and then, 1 mM isopropyl β-D-thiogalacto-pyranoside (IPTG, Sigma) was added thereto to induce expression of HCCR-1 protooncogene. The C-terminal portion of HCCR-1 protein fused with maltose binding protein (MBP, 42 kDa) derived from vector pMAL-p2 was expressed which has the molecular weight of approximate 64 kDa. The 64 kDa fusion protein was purified from the culture using pMAL protein fusion and purification system (New England Biolab., USA).
Then, ten 3-month-old New Zealand white rabbits each weighing about 2.5 kg were intraperitoneally administered with 1 mg of the fusion protein weekly for 3 times. The blood sample was obtained from the immunized rabbits and centrifuged to obtain a serum containing a polyclonal antibodies.
EXAMPLE 1
Preparation of Mouse Cell Transfected with HCCR-1 Protooncogene
NIH/3T3 cells (ATCC CRL 1658), differentiated mouse fibroblast cell line, were transfected with expression vector pcDNA3/HCCR-1 obtained in Preparation Example 1 using Lipofectamine (Gibco BRL), and the resulting NIH/3T3 cells were cultured in Waymouth MB 752/1 medium supplemented with G418 (Gibco) to obtain the NIH/3T3 cell transfected with HCCR-1 protooncogene, designated HCCR-1M, which was deposited with Korean Collection for Type Cultures on Dec. 26, 2000 under the accession number of KCTC 0923BP.
EXAMPLE 2
Preparation of Human Cell Transfected with HCCR-1 Protooncogene
The procedure of Example 1 was repeated except that 293 cells (ATCC CRL-1573) were used instead of NIH/3T3 cells, to obtain the 293 cell transfected with HCCR-1 protooncogene, designated HCCR-1H, which was deposited with Korean Collection for Type Cultures on Dec. 26, 2000 under the accession number of KCTC 0922BP.
COMPARATIVE EXAMPLE
Preparation of Comparative Cell Transfected with Vector pcDNA3 
The procedure of Example 1 was repeated except that vector pcDNA3 (Invitrogen) was used instead of vector pcDNA3/HCCR-1 to obtain comparative cells transfected with vector pcDNA3.
EXAMPLE 3
Morphological Characteristics of HCCR-1 M Cell
(Step 1) Phase-contrast features of HCCR-1M cell
HCCR-1M cells obtained in Example 1 were cultured in monolayer in Waymouth MB 752/1 medium and the resulting HCCR-1M cells were examined under the phase-contrast microscope. The parental wild-type NIH/3T3 cells were used as a control.
FIGS. 1A and 1B are the respective phase-contrast features of monolayer-cultured HCCR-1M and parental wild-type NIH/3T3 cells. As can be seen from FIGS. 1A and 1B, the parental wild-type NIH/3T3 cells are spindle shaped cells having a long slender nucleus and a scanty amount of cytoplasm, while HCCR-1M cells have a polygonal shape with an ovoid nucleus and plump cytoplasm.
(Step 2) Hematoxylin-eosin Staining
HCCR-1M cells obtained in Example 1 were cultured in monolayer in Waymouth MB 752/1 medium and the resulting HCCR-1M cells were stained with hematoxylin-eosin.
FIG. 2 is the hematoxylin-eosin staining result of monolayer-cultured HCCR-1M cells. As can be seen from FIG. 2, HCCR-1M cells exhibit nuclear pleiomorphism, distinct nucleoli, granular chromatin patterns, tumor giant cells and atypical mitotic figures.
(Step 3) TEM
HCCR-1M cells obtained in Example 1 were subjected to TEM according to the procedure of Reference Example 1.
FIG. 3 is the TEM picture of HCCR-1M cell wherein the scale bar represents the length of 3 μm and the inset is higher magnification of area indicated by circle (scale bar, 1 μm). As can be seen from FIG. 3, the HCCR-1M cells have microvilli on the cell surface, lobulated nucleus with prominent nucleoli and well-developed rough endoplasmic reticula (rER) and Golgi complexes (circle).
The above results show that HCCR-1M cell has morphological characteristics of tumor giant cell.
EXAMPLE 4
Tumorigenicity of HCCR-1M cell
5×106 each of HCCR-1M cells obtained in Example 1 were injected subcutaneously into the posterior lateral aspect of the trunk of 9 nude mice (5-week-old athymic nu/nu on BALB/c background).
All 9 nude mice injected with HCCR-1M cells showed palpable tumors after 21 days. FIG. 4 is the photograph of the nude mouse allografted with HCCR-1M cells. This suggests that the HCCR-1M cells have a tumorigenicity.
When the subcutaneous tumors reached 1.5-2.5 cm in diameter, the nude mice were sacrificed and the tumors were removed therefrom which was used in the following tumor analysis and establishment of cell line.
EXAMPLE 5
Characteristics of Tumor Nodule of Nude Mouse Grafted with HCCR-1M Cell
Characteristics of nude mouse's tumor nodules induced by HCCR-1M allograft were examined as follows.
(Step 1) Hematoxylin-eosin Staining
The tumor nodules obtained in Example 4 were stained with hematoxylin-eosin staining.
FIG. 5 is the hematoxylin-eosin staining result (×250) of the tumor nodules. As can be seen from FIG. 5, the tumor nodules have typical epithelial cell nests separated by fibrous stroma.
(Step 2) TEM
The tumor nodules obtained in Example 4 were subjected to TEM according to the procedure of Reference Example 2.
FIG. 6 is the TEM picture of the tumor nodules wherein the scale bar has the length of 3 μm and the inset is higher magnification of area indicated by circle (scale bar, 0.5 μm). As can be seen from FIG. 6, the cells of tumor nodules have well-developed organelles and are tightly connected by desmosomes. This suggests that the HCCR-1M cells were changed into epidermal cells.
(Step 3) Immunohistochemical Analysis
The tumor nodules obtained in Example 4 were subjected to immunohistochemistry according to the procedure of Reference Example 3 using each of anti-reticulin fiber, anti-keratin, anti-EMA (epithelial membrane antigen) and anti-vimentin antibodies (DAKO) as a primary antibody.
FIGS. 7A to 7D are the immunohistochemical analysis results (×250) showing the expression of reticulin fibers, keratin, EMA and vimentin, respectively, in the tumor nodules. As can be seen from FIGS. 7A to 7D, the cell nests were enveloped by reticulin fibers (FIG. 7A) and the cells showed coexpression of epithelial markers, such as keratin (FIG. 7B) and EMA (FIG. 7C) and of the mesenchymal marker, vimentin (FIG. 7D). These results suggest that HCCR-1 protooncogene caused the conversion of the mesenchymal NIH/3T3 cells to epithelial cells.
Particularly, the mesenchymal NIH/3T3 cell introduced with an oncogene transforms into sarcoma, whereas the nude mouse allografted with HCCR-1M cell develops a palpable tumor.
EXAMPLE 6
Preparation of Cancer Cell Line from Nude Mouse Allografted with HCCR-1M cell
Cells were isolated from the tumor nodules obtained in Example 4 and then cultured in Waymouth MB 752/1 medium supplemented with 20% bovine fetal serum, which were designated HCCR-1MN cell.
EXAMPLE 7
Characteristics of HCCR-1MN Cells
The HCCR-1MN cells obtained in Example 6 were subjected to phase-contrast microscopy by repeating the procedure of Step 1 of Example 3.
FIG. 8 is the phase-contrast feature (×300) of monolayer-cultured HCCR-1MN cells. As can be seen from FIG. 8, HCCR-1MN cells have morphological characteristics similar with those of HCCR-1M cells represented in Step 1 of Example 3.
EXAMPLE 8 
Western Blot Analyses of HCCR-1M and HCCR-1MN Cells
To examine expression of HCCR-1 protooncogene in HCCR-1M and HCCR-1MN cells, HCCR-1M and HCCR-1MN cells obtained in Examples 1 and 6, respectively, were subjected to western blot analysis according to the procedure of Reference Example 2 using the anti-HCCR-1 serum obtained in Preparation Example 2. For the comparison, the parental wild-type NIH/3T3 cells and the comparative NIH/3T3 cells obtained in Comparative Example were used in the western blot analysis.
FIG. 9 is the western blot analysis result showing the expression of HCCR-1 protooncogene in HCCR-1M and HCCR-1MN cells. As can be seen from FIG. 9, the HCCR-1 protein is overexpressed in HCCR-1M and HCCR-1MN cells, but not in the parental wild-type NIH/3T3 cells and comparative NIH/3T3 cells transfected with vector pcDNA3, as represented as weak band.
EXAMPLE 9
Characteristics of HCCR-1H Cell
To examine morphological characteristics of HCCR-1H cell, the HCCR-1H cells were subjected to phase-contrast microscopy according to the procedure of Step 1 of Example 3. The parental wild-type 293 cells were used as a control.
FIGS. 10A and 10B are the respective phase-contrast features (×300) of monolayer-cultured HCCR-1H and parental wild-type 293 cells. As can be seen from FIGS. 10A and 10B, the HCCR-1H cell has increased cell dimension and cellularity compared with the wild-type 293 cell.
EXAMPLE 10
Tumorigenicity of HCCR-1H Cell
To examine tumorigenicity of HCCR-1H cell, the procedure of Example 4 was repeated using HCCR-1H cells obtained in Example 2.
Nude mice xenografted with HCCR-1H cells showed palpable tumors after 21 days. This suggests that the HCCR-1H cell has a tumorigenicity.
When the tumors reached 1-1.5 cm in diameter, the nude mice were sacrificed and the tumors were removed therefrom which was used in the following tumor analysis.
EXAMPLE 11
Characteristics of Tumor Nodule of Nude Mouse Grafted with HCCR-1H Cell
Characteristics of nude mouse's tumor nodules induced by HCCR-1H allograft were examined as follows.
(Step 1) Hematoxylin-eosin Staining
The tumor nodules obtained in Example 10 were stained with hematoxylin-eosin staining.
FIG. 11 is the hematoxylin-eosin staining result (×250) of the palpable tumor nodules. As can be seen from FIG. 11, the tumor nodule has characteristics of typical epithelial cell carcinomas, i.e., atypism of cell shape, pleomorphism, nucleolar enlargement, and increased volume ratio of nucleus to cytoplasm.
(Step 2) immunohistochemical Analysis
The tumor nodules obtained in Example 10 were subjected to immunohistochemistry according to the procedure of Reference Example 3 using each of anti-cytokeratin-8, anti-cytokeratin-19 and anti-vimentin antibodies (DAKO) as a primary antibody.
FIGS. 12A to 12C are the immunohistochemical analysis results (×250) showing the expression of cytokeratin 8, cytokeratin 19 and vimentin, respectively, in the palpable tumor nodules. As can be seen from FIGS. 12A to 12C, the tumor cells showed coexpression of epithelial markers, such as cytokeratin-8 and -19 (FIGS. 12A and 12B), and the mesenchymal marker, vimentin (FIG. 12C). These results suggest that HCCR-1 protooncogene caused the conversion of the mesenchymal 293 cells to epithelial cells.
EXAMPLE 12
Northern Blot Analysis of HCCR-1H Cell
To examine expression level of HCCR-1 protooncogene in HCCR-1H cells, total RNAs were isolated from HCCR-1H cells obtained in Example 2 according to the procedure of Reference Example 4 and subjected to northern blot according to the procedure of Reference Example 5 using 32P-labeled random HCCR-1 cDNA probe.
FIG. 13 is the northern blot result showing the expression of HCCR-1 protooncogene in HCCR-1H and parental wild-type 293 cells. As can be seen from FIG. 13, about 2.1 kb mRNA single transcript was overexpressed in HCCR-1H cells while not in the parental wild-type 293 cells.
EXAMPLE 13
Tumorigenesis Mechanism Induced by HCCR-1 Protooncogene in Mouse Cells
To examine the tumorigenesis mechanism induced by HCCR-1 protooncogene in mouse cells, abnormalities of protein kinase C (PKC) and telomerase activities, loss of cell cycle checkpoint control, alteration of egr-1, c-fos and GAPDH expression, which have been reported to be relevant to the tumorigenesis process, were assessed as follows.
(Step 1) PKC Activity Assay
Generally, tumors develop secondarily to abnormalities in PKC-mediated signal transduction process. To ensure that HCCR-1 modulates the protein kinase C (PKC) activity, PKC assay was performed using parental wild-type NIH3T3 cells, comparative NIH/3T3 cells transfected with vector pcDNA3 obtained in Comparative Example and HCCR-1M cells obtained in Example 1.
PKC activity was measured using the SigmaTECTTM Protein Kinase C Assay System (Promega) according to the manufacturer's instructions. PKC activity was defined as the difference of the amounts of PKC incorporated into substrate per minute in the absence and presence of phospholipids. Each value is the means ±s.d. of three independent experiments.
FIG. 14 is the graph showing PKC activities of parental wild-type NIH/3T3 cell, comparative NIH/3T3 cell transfected with vector pcDNA3 and HCCR-1M cell. As can be seen from FIG. 14, the PKC activity of HCCR-1M cells is about 10-fold higher than the wild-type. This suggests that HCCR-1 protooncogene enhances the cellular PKC activity.
(Step 2) Telomerase Activity Assay
Based on the report that PKC induces a marked increase in telomerase activity, telomerase activity assay was performed using wild-type NIH/3T3 cells, comparative NIH/3T3 cells transfected with vector pcDNA3 obtained in Comparative Example and HCCR-1M cells obtained in Example 1.
Telomerase activity was measured using the telomerase PCR-ELISA kit (Boehringer Mannheim, USA) according to the manufacturer's instructions. Human telomerase-positive immortalized human kidney cells provided in the kit were used as a positive control. Used as a negative control was the 293 cells pretreated with RNase. Assays were performed with an extract amount equivalent to 1×103 cells. Results show the average mean optical density (OD) values from four separate experiments (means ±s.d.).
FIG. 15 is the graph showing telomerase activities of positive control cell, negative control cell, parental wild type NIH/3T3 cell, comparative NIH/3T3 cell transfected with vector pcDNA3 and HCCR-1M cells. As can be seen from FIG. 15, the wild-type NIH/3T3 cells showed detectable telomerase activity while HCCR-1M cells have the increased telomerase activity by a factor of about 7 as compared with the parental wild-type cells. The telomerase activity of the positive control cell is high while that of the negative control cells is not detectable. These results are consistent with the previous study (Holt, S. E., Wright, W. E. and Shay J. W. Mol. Cell Biol. 16, 2932-2939 (1996)), suggesting that HCCR-1M cell has high telomerase activity induced by activated PKC.
(Step 3) Cell Cycle Test
Tumor cells typically have acquired damage to genes that directly regulate their cell cycles. In order to examine whether there was an alternation in growth properties of HCCR-1M cells, the cell cycle profiles was determined as follows.
HCCR-1M and parental wild-type NIH/3T3 cells cultured at mid-log phase were growth arrested by incubation in a DMEM medium containing 0.5% fetal calf serum for 36 hours. Cells were treated with trypsin, harvested and fixed in 70% ethanol. 50 μg/ml of a propidium iodide staining solution (Sigma) and 100 units per ml of RNase A (Boerhinger Mannheim) were added to 2×106 cells. After incubation for 30 min., the cellular DNA content was determined by fluorescence analysis at 488 nm using a FACS Caliber (Becton Dickinson). A minimum of 1×104 cells per sample was analyzed with Modfit 5.2 software.
Percentage of parental wild-type NIH/3T3 and HCCR-1 cells in G0/G1, S and G2/M phases were determined and the results are shown in Table I.










TABLE I









Wild-type NIH/3T3
HCCR-1M














G0/C1
S
G2/M
G0/G1
S
G2/M





Cell Percentage
55.7
20.6
24
46.6
31.5
22.4









As can be seen from Table I, the percentage of wild-type NIH/3T3 and HCCR-1M cells in S-phase was 20.6% and 31.5%, respectively. These results suggest that there was a significant shift of the cell population out of the G0/G1-phase into the S-phase in HCCR-1M cells.
To assess the serum-dependent cell cycle progression, HCCR-1M and parental wild-type NIH/3T3 cells were cultured in DMEM medium containing 0.5% fetal calf serum for 36 hours to arrest the growth. The cells were transferred into DMEM medium containing 20% fetal calf serum and harvested at indicated times to determine percentage of cells in G0/G1, S and G2/M phases. The results are shown in Table II.









TABLE II









Cell Percentage










Wild-type NIH/3T3
HCCR-1M













Time (hour)
G0/C1
S
G2/M
G0/G1
S
G2/M
















0
77
8.0
14.9
70
21.8
8.7


12
72.2
14.0
14.2
66.9
24.0
9.6


24
49.6
13.4
37.2
56.7
24.7
19.2


48
58.3
18.3
23.7
52.7
30.4
17.5









As can be seen from Table II, the percentage of parental wild-type NIH/3T3 cells in S-phase at 0 hour was 8% while the percentage of HCCR-1M cells in S-phase was 21.8%. These results suggest that constitutive overexpression of HCCR-1 protooncogene allowed for a relative amount of resistance to serum deprivation-induced G0/G1 arrest. After transferring cells into DMEM medium containing 20% serum to release cells from the growth arrest, there were consistent increases of over 10% in the S-phase populations of HCCR-1M cells as compared to wild-type NIH/3T3 cells. Therefore, overexpression of HCCR-1 protooncogene could deregulate cell growth by shortening the G0/G1-phase and increasing the S-phase population of cells.
(Step 4) Expression Patterns of egr-1, c-fos and GAPDH
Based on the fact that expression patterns of egr-1, c-fos and GAPDH involve in tumor formation, expression patterns of egr-1, c-fos and GAPDH in HCCR-1M cells obtained in Example 1 were examined as follows.
Growth of HCCR-1M and parental wild-type NIH/3T3 cells in mid-log phase were arrested by incubation in a DMEM medium containing 0.5% fetal calf serum for 36 hours (quiescent period). The cells were transferred into fresh DMEM medium containing 20% fetal calf serum and cultured for 0, 15, 30, 60 and 120 min. to stimulate the growth (mitotic period). Total RNAs were isolated from quiescent and mitotic cells according to the procedure of Reference Example 4 and subjected to northern blot according to the procedure of Reference Example 5 using 32P-labeled random-primed egr-1, c-fos and GAPDH cDNA probe.
FIGS. 16A, 16B and 16C are the northern blot results showing the expression of egr-1, c-fos and GAPDH, respectively, in HCCR-1H and parental wild-type NIH/3T3 cells. As can be seen from FIGS. 16A to 16C, mitotic HCCR-1M cells show a marked down-regulation of egr-1 expression, up-regulation of GAPDH and no significant difference of c-fos expression compared with the wild-type cells.
These results suggest that deregulation of HCCR-1 gene in mouse NIH/3T3 cells may result in the activation of PKC or telomerase, loss of particular cell cycle checkpoint controls, and downregulation of egr-1 expression, thereby predisposing cells to malignant conversion.
EXAMPLE 14
Tumorigenesis Mechanism Induced by HCCR-1 Protooncogene in Human Cell
To examine the tumorigenesis mechanism induced by HCCR-1 protooncogene in a human cell, expression patterns of p53 tumor suppressor, MDM2, Bax, p21WAF1, p16INK4A and p14ARF genes, which have been reported to be relevant to the tumor, were tested as follows.
(Step 1) Expression Pattern of p53 Tumor Suppressor
In order to examine the expression pattern of p53 in HCCR-1H cell, western and northern blot analyses were conducted as follows.
HCCR-1H cells obtained in Example 2 and parental wild-type 293 cells were lysed and the lysates were subjected to western blot using monoclonal anti-p53 antibody DO-7 (amino acids 37 to 45; Novocastra Laboratories, Ltd., UK) which reacts with wild-type p53 alone; or Ab-5 (Clone DO-7) (amino acids 37 to 45; NEOMARKERS, INC., CA) which reacts with wild-type and mutant p53, according to the procedure of Reference Example 2. The same blot was reacted with anti-human mouse β-actin antibody (Sigma) to confirm total protein content.
FIG. 17A is the western blot showing the expression of p53 tumor suppressor in HCCR-1H and parental wild-type 293 cells; and FIG. 17B is the western blot showing β-actin of the same blot. As can be seen from 17A, p53 protein levels were markedly elevated in HCCR-1H cells as compared with the parental wild-type 293 cells.
Further, HCCR-1H cells obtained in Example 2 were cultured in methionine-free RPMI 1640 medium containing 2% fetal calf serum and 2 mM glutamine (Sigma) for 2 hours and then labeled with 100 μl of L-35S methionine (Amersham). The cells were washed with 1×Hanks buffer (Gibco, USA), and then further cultured in normal RPMI 1640 medium containing L-methionine for 0.5, 1, 2 or 4 hours. The cells were dissolved in an immunoprecipitation solution (50 mM Tris[pH8.0], 5 mM EDTA, 150 mM NaCl, 1% NP-40, 1 mM phenylmethylsulfonyl fluoride, 10 mM benzamidine, 1 μg of pepstatin per ml, 10 mM sodium bisulfite), washed with 50 μl of protein A-sepharose solution (Sigma) and then quantified. The cell lysate was subjected to immunoprecipitation (Kessler, S. W., J. Immunol., 115, 1617-1623 (1975)) using anti-p53 antibody followed by SDS-PAGE. The above procedure was repeated using Hep 3B hepatoma cells (ATCC HB-8064), as a control lacking p53 gene.
FIG. 18 is the immunoprecipitation result showing the expression of p53 tumor suppressor in HCCR-1H and parental wild-type human 293 cells. As can be seen from FIG. 18, p53 protein levels were markedly elevated in HCCR-1H cells as compared with parental wild-type 293 cells. Therefore, it is believed that in the tumorigenesis mechanism induced by HCCR-1 protooncogene, p53 protein is highly expressed but remains in an inactive form which does not suppress the tumor.
(Step 2) Expression Patterns of MDM2, bax, p21WAF1, p16IN4A and p14ARF Genes
Since p53 is a part of a regulatory loop that also involves MDM2, Bax and p14ARF, while directly influencing tumor suppressor genes p21WAF1 and p16INK4A, expression patterns of MDM2, Bax, p14ARF, p21WAF1 and p16INK4A were assessed.
Using HCCR-1H cells obtained in Example 2; and anti-MDM2, anti-Bax, anti-p21WAF1 and anti p16INK4A antibodies (Oncogene Research Products, USA) and p14ARF (Lab Vision, USA), western blot was conducted according to the procedure of Reference Example 2. The same blot was reacted with anti-β-actin antibody to confirm the total protein content.
FIGS. 19A, 19C, 19E, 19G and 19I are the western blot analysis results showing the expression of MDM2, Bax, p21WAF1, p16INK4A and p14ARF, respectively, in HCCR-1H cell; and FIGS. 19B, 19D, 19F, 19H and 19J are β-actin in each of the above blots. As can be seen from FIGS. 19A, 19C, 19E and 19G, MDM2, Bax, p21WAF1, p16INK4A and p14ARF protein levels are decreased compared with the parental wild-type 293 cells. These results suggest that HCCR-1 overexpression may specifically inhibit the transcription of MDM2, Bax, p21WAF1 and p16INK4A, thereby reducing the protein levels thereof.
In summarizing these results together with those of Step 1, it is believed that overexpression of HCCR-1 gene increases p53 stability but the p53 protein does not form an autoregulatory loop which regulates expression of MDM2, bax and p21WAF1 positively. Particularly, as can be seen from FIGS. 19E and 19G, kinase inhibitor protein family p21WAF1 and p16INK4A were downregulated in HCCR-1H cells by a p53-independent mechanism. As can be seen from FIG. 19I, p14ARF did not appear to be aberrantly expressed either in parental wild-type 293 nor in HCCR-1H cells. These results suggest that alteration of the MDM2-p14ARF loop is not a likely mechanism of p53 inactivation.
The above results together with those of Step 3 of Example 13 indicate that the overexpression of HCCR-1 protooncogene both in mouse and human cells can affect cell cycle control and has a correlation with the p53 and p21 cell cycle regulators.
(Step 3) Protein-protein Interaction Partner of HCCR-1
To determine a partner of HCCR-1 in the protein-protein interaction, a yeast two-hybrid screen was conducted as follows.
E. coli JM-109/HCCR1 (KCTC 0667BP) cells were cultured and expression vector pCEV-LAC/HCCR-1 was isolated therefrom. Expression vector pCEV-LAC/HCCR-1 was cleaved with SalI and HCCR-1 protooncogene thus obtained was inserted at BamHI/SalI sites of yeast two-hybrid vector (Clontech, USA) containing pLexA DNA-binding domain to obtain vector pLexA-HCCR-1 expressing a fusion protein of pLexA DNA-binding domain with HCCR-1 protein. Vector pLexA-HCCR-1 was mixed with yeast EGY48 (Clontech, USA) and heated at 42° C. for 10 min. to transform the yeast. The resulting yeast was transformed with human fetal brain cDNA library fused with pB42AD containing pLexA-activating domain (Clontech, USA) in the same method. β-galactosidase filter lift assays were performed by replicaplating the transformant into Trp−, Leu−, His− selection plates. When a transformant has a partner gene derived from cDNA library, the partner protein fused with pLexA-activating domain binds to HCCR-1 protein fused with pLexA DNA-binding domain to form a blue colony on a plate medium containing X-gal. To eliminate false positives, yeast mating assay (Guarente, L., Proc. Natl. Acad. Sci. USA, 90, 1639-1641 (1993)) was conducted.
From the clones thus obtained, a gene encoding a protein-protein interaction partner of HCCR-1 was screened.
The colony thus obtained was cultured in glucose medium and vector containing the partner gene was extracted therefrom using glass beads. The vector was introduced into E. coli KC8 (Clontech, USA) by electroporation and the resulting E. coli KC8 cells were plated on M9 minimal medium to select a transformant. Plasmid DNA was extracted from the transformant and E. coli DH5α was transformed with the plasmid DNA and cultured in LB medium to amplify the plasmid DNA. Plasmid DNA was extracted from the culture and cleaved with HindIII to obtain 1 kb fragment containing the partner gene. The nucleotide sequence of the partner gene was determined to identify TPD52L2 gene (GenBank accession number NM003288). D52 protein encoded by TPD52L2 gene was originally identified through its elevated expression level in human breast carcinoma, and play roles in calcium-mediated signal transduction and cell proliferation (Byrne, J. A., et al., Cancer Res., 55, 2896-2903 (1995); and Byrne, J. A., et al., Oncogene, 16, 873-881 (1998)).
(Step 4) Co-transfection
In order to examine interaction of HCCR-1 and D52 proteins, co-transfection was conducted as follows.
E. coli JM-109/HCCR1 (KCTC 0667BP) cells were cultured and expression vector pCEV-LAC/HCCR-1 was isolated therefrom. Expression vector pCEV-LAC/HCCR-1 was cleaved with SalI and the full length HCCR-1 cDNA thus obtained was inserted at SalI site of expression vector N-terminal pFALG-CMV (Sigma, USA) to obtain expression vector pFLAG-HCCR-1 expressing a fusion protein of FLAG with HCCR-1. TPD52L2 gene obtained in Step 3 was inserted at NotI site of expression vector pcDNA3 (Invitrogen, USA) to obtain expression vector pGST-TPD52L2 expressing a fusion protein of GST with D52.
CHO cell was co-transfected with expression vectors pFLAG-HCCR-1 and pGST-TPD52L2 and then cultured in RPMI 1640 medium. After 48 hours, the CHO cells were treated with trypsin and harvested. The CHO cells were washed with PBS and then resuspended in IP buffer (10 mM Tris-HCl [pH 7.4], 150 mM NaCl, 1% NP40, 2 mM sodium vanadate, 10 mM sodium fluoride, 10 mM sodium pyrophosphate, 5 mM EDTA, 10 μg/ml aprotinine, 10 μg/ml leupeptine, 10 μg/ml pepstatine, 1 mM phemylmethylsulfonyl fluoride). The cell suspension was then passed through a 27-gauge needle and the resulting cell lysate was spun to pellet the unbroken cells. The supernatant was precleared by mixing with preimmune IgG and protein A beads (Sigma, USA). FLAG-HCCR-1 or GST-TPD52L2 fusion protein in the cell lysate was immunoprecipitated using anti-FLAG or anti-GST antibody (Sigma, USA) (Kesler, S. W., J. Immunol., 115, 1617-1623 (1975)). The residual protein samples were subjected to western blot using anti-GST or anti-FLAG antibody according to the procedure of Reference Example 2.
FIGS. 20A and 20B are the western blot analysis results showing GST protein and PLAG protein, respectively. As can be seen from FIGS. 20A and 20B, the fusion protein was detected in both precipitates. These results suggest that D52 protein interacts with HCCR-1 protein.
EXAMPLE 15
Preparation of Transgenic Mouse
In order to ensure that the HCCR-1 protooncogene induce tumorigenesis in vivo, a transgenic mouse expressing HCCR-1 protooncogene under the CMV promoter.
To obtain HCCR-1 cDNA useful in the preparation of a transgenic mouse, E. coli JM-109/HCCR1 cells (KCTC 0667BP) were cultured and expression vector pCEV-LAC/HCCR-1 was isolated therefrom. Expression vector pCEV-LAC/HCCR-1 was cleaved with SalI and the full length HCCR-1 cDNA thus obtained was inserted at XhoI site of expression vector pcDNA3 to obtain expression vector pcDNA3-HCCR-1. Expression vector pDNA3-HCCR-1 was cleaved with SalI and XmnI, electrophoresed on 0.7% agarose gel, and isolated by electroelution. The isolated DNA fragment was dialyzed against 10 mM Tris-HCl (pH 7.4)/0.2 mM EDTA solution and adjusted to a final concentration of 4 ng/ml. The structure of the resulting DNA contains CMV promoter, HCCR-1 cDNA gene and bovine growth hormone (bGH) polyA sequence as shown in FIG. 21.
The DNA was microinjected into a zygote of mouse FVB/N strain (Samyuk Corp., CAMTAKO, Korea) according to pronuclear DNA microinjection method (Gordon, J. W., et al., Pro. Natl. Acad. Sci. USA, 77, 7382-7384 (1980)): The DNA solution was microinjected into the pronucleus of 1-cell stage zygote and the resulting zygote was incubated for 20 hours to select the 2-cell stage embryo. The 2-cell stage embryo was implanted into oviduct of pseudopregnant, recipient ICR mouse (Samyuk Corp., CAMTAKO, Korea). The progeny mice were obtained from the recipient mouse, and DNA samples obtained by tail biopsy of the progeny mice were subjected to southern blot analysis.
FIG. 22 is the transgenic mouse derived from the embryo introduced with HCCR-1 protooncogene. As can be seen from FIG. 22, the tumor mass, measuring about 1.5 cm×1.5 cm, is noted in the right axillary area adjacent to the breast.
The tumor was isolated and observed with the naked eye.
FIG. 23 is the photograph of the breast tumor of transgenic mouse. As can be seen from FIG. 23, the tumor of transgenic mouse is single, well-circumscribed nodule without capsule.
To examine the morphological features of the tumor, the tumor was stained with hematoxylin-eosin. FIG. 24 is the hematoxylin-eosin staining result of the tumor. As can be seen from FIG. 24, the tumor consists of papillary structures and glandular or duck-like structures. Extensive necrosis is noted in the central portion. Normal breast tissue is evident adjacent to the tumor. Cuboid or ovoid cells have indistinct border and a moderate amount of granular, eosinophilic cytoplasm. The tumor cells have an large, pleomorphic and hyperchromatic nuclei and many mitoses, including some atypical forms. Small but distinct nucleoli are noted. These results suggest that the tumor of transgenic mouse exhibits characteristics of ductal papillary adenocarcinoma of breast.
FIG. 25 is the transmission electron microscope picture of the tumor, wherein the scale bar represents the length of 2 μm. As can be seen from FIG. 25, ovoid tumor cells have abundant cytoplasmic organelles. Nuclei have clumping and margination of chromatin and distinct nucleoli. Cytoplasm is filled with some mitochondria and many vesiculated rER. Some desmosomes are evident.
The embryo of the transgenic mouse was designated HCCR-1, which was deposited on Dec. 26, 2000 with the Korean Collection for Type Cultures under the accession number of KCTC 0924BP.
EXAMPLE 16
Expression of HCCR-1 Protooncogene in Breast, Kidney, Ovary and Stomach Tumor Tissues
To examine the expression of HCCR-1 protooncogene in breast, kidney, ovary and stomach tumor tissues, total RNA was isolated from the breast, kidney, ovary and stomach tumor tissues according to the procedure of Reference Example 4 and subjected to northern blot analysis according to the procedure of Reference Example 5 using 32P-labeled random HCCR-1 cDNA probe. For the comparison, the above procedures were repeated using normal breast, kidney, ovary and stomach tissues.
FIG. 26A is the northern blot analysis result showing the expression of HCCR-1 protooncogene in breast, kidney, ovary and stomach tumor tissues; and FIG. 26B is the same blot hybridized with β-actin probe. As can be seen from FIGS. 26A and 26D, the human breast, kidney, ovary and stomach tumor tissues showed increased expression of HCCR-1 protooncogene when compared with the normal tissues.
To examine the HCCR-1 protein expressed in the breast, kidney, ovary and stomach tumor tissues, the breast, kidney, ovary and stomach tumor tissues were subjected to western blot analysis using anti-HCCR-1 serum obtained in Preparation Example 2 according to the procedure of Reference Example 2.
FIG. 27 is the western blot analysis result showing the expression of HCCR-1 protooncogene in human breast, kidney, ovary and stomach cancer tissues. As can be seen from FIG. 27, the human breast, kidney, ovary and stomach tumor tissues showed increased expression of 50 kDa HCCR-1 protein expression when compared with their normal counterparts, respectively.
EXAMPLE 17
Chromosomal Localization of HCCR-1 Protooncogene
The full length HCCR-1 cDNA obtained in Preparation Example 1 was labeled using random prime labeling kit (Promega, USA) to obtain a probe. Human placenta Lambda Genomic Library (Stratagene, USA) was screened using the probe to obtain 20 kb genomic DNA.
The genomic DNA was subjected to fluorescence in situ hybridization (FISH) (Cherif, D., et al., Proc. Natl. Acad. Sci. USA, 87, 6639-6649 (1990)): The genomic DNA on a slide was labeled with SpectrumRed-dUTP using nick translation kit (Vysis, USA). The slide was observed under a Zeiss fluorescence microscope. Chromosomes were counterstained with DAPI (Sigma, USA).
FIG. 28 is the fluorescence in situ hybridization analysis result showing that HCCR-1 protooncogene is located on long arm (12q) of 12th chromosome.
While the subject invention has been described and illustrated with reference to the preferred embodiments only, it may be apparent to those skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope of the present invention which is defined in the appended claims.

## Claims

1. An isolated mammalian cell transformed with an expression vector comprising a human protooncogene which has a nucleotide sequence of SEQ ID NO: 1.

2. The isolated mammalian cell of claim 1, which is mouse cell line HCCR-1M(KCTC 0923BP) or human cell line HCCR-1H(KCTC 0922BP).

3. A mouse embryo whose genome carries an introduced nucleic acid construct comprising a human protooncogen which has the nucleotide sequence of SEQ ID NO: 1.

4. The mouse embryo of claim 3, wherein the mouse is FVB/N strain.

5. The mouse embryo of claim 4, which is mouse embryo HCCR-1(KCTC 0924BP).

6. A transgenic cancer mouse derived from the embryo of claim 3.

7. The transgenic mouse of claim 6, wherein the cancer is ductal papillary adenocarcinoma of breast.

8. A transgenic cancer mouse derived from the embryo of claim 4.

9. A transgenic cancer mouse derived from the embryo of claim 5.