bluuebunny/crossref_metadata_2025_split huggingface dataset:
Detection of novel non‐ras oncogenes in rat nasal squamous cell carcinomas
Authors: Hochwalt Anne E. , Wirgin Isaac , Felber Mary , Currie Diane D. , Garte Seymour J. 
Published: February 2007

AbstractRat nasal squamous cell carcinomas induced by inhalation of three direct‐acting alkylating agents yielded DNA containing activated oncogenes with no homology to any member of the ras family. The novel NIH 3T3 transforming oncogenes from tumors induced by β‐propiolactone and methylmethane sulfonate are distinct from each other based on restriction analysis. The gene isolated from β‐propiolactone—induced tumors is between 6 and 9 kb in size. None of the tumors induced by dimethylcarbamyl chloride contained positive DNA in the NIH 3T3 focus assay or in the nude mouse cotransfection assay. The rat nasal tumor model is apparently ideally suited for analysis of the roles of carcinogen and tissue specificity in oncogene activation, especially related to novel (non‐ras) transforming oncogenes.
Comparison of three recombinant murine leukemia viruses carrying the v‐src oncogene of avian sarcoma virus: Differences in in vitro transformation and in vivo pathogenicity
Authors: Feuerman Miriam H. , Lee William T.‐L. , Pattengale Paul K. , Fan Hung 
Published: February 2007

AbstractWe previously described a recombinant Moloney murine leukemia virus (Mo‐MuLV) carrying the v‐src oncogene, Mo‐MuLV(src). Mo‐MuLV(src) encodes a gag‐src fusion protein, transforms cells in culture, and induces fibrosarcomas in vivo. To compare transforming properties of the gag‐src fusion protein to pp60src encoded by Rous sarcoma virus, we constructed a new recombinant virus, Mo‐MuLV(+src). Mo‐MuLV(+src) encodes pp60src in the context of Mo‐MuLV. Cells transformed by Mo‐MuLV(+src) were round and formed colonies in soft agar, whereas Mo‐MuLV(src)‐infected cells were fusiform and did not grow in suspension. Thus, the extent of transformation induced by Mo‐MuLV(+src) was greater than that induced by Mo‐MuLV(src). Subcutaneous inoculation of either virus into neonatal NIH Swiss mice resulted in fibrosarcomas at the site of injection. Further studies indicated that tumors induced by Mo‐MuLV(+src) grew rapidly but rarely metastasized. In contrast, tumors induced by Mo‐MuLV(src) grew somewhat more slowly but metastasized with a high frequency (60%). These viruses may provide a useful model system for tumor metastasis. Another src‐containing virus was also studied, MRSV (constructed by Anderson and Scolnick). MRSV also encodes pp60src but in the context of amphotropic MuLV. When injected intravenously into six‐week‐old mice, MRSV induced splenomegaly and spleen foci but no solid tumors, as reported previously. In contrast, Mo‐MuLV(src)‐induced fibrosarcomas mostly in the spleen under the same inoculation protocol. These results suggest that the v‐src oncogene was the major pathogenic determinant in neonatal mice for all three src‐containing viruses; however, variations in the nature of the transforming protein modulated the behavior of the induced tumors. In adult mice, greater differences in pathogenicity were observed.
Aberrant expression during two‐stage mouse skin carcinogenesis of a type 147‐kDa keratin, k13, normally associated with terminal differentiation of internal stratified epithelia
Authors: Nischt Roswitha , Roop Dennis R. , Mehrel Thomas , Yuspa Stuart H. , Rentrop Martin , Winter Hermelita , Schweizer Jürgen 
Published: February 2007

AbstractSpecific keratin cDNA probes and monospecific antikeratin antisera were used to analyze mouse epidermis and epidermal tumors for the expression of a type I 47‐kDa keratin, K13, normally associated with terminal differentiation of internal stratified epithelia. We demonstrated that this keratin was virtually absent from the entire body epidermis at various stages of development. Also, it was not detected in various forms of acute and chronic epidermal hyperproliferation or in epidermal cells cultured under conditions that favored either cell proliferation or in vitro differentiation. In contrast, K13 was consistently expressed in squamous cell carcinomas of the skin induced by 7,12‐dimethylbenz[a]anthracene and 12‐O‐tetradecanoylphorbol‐13‐acetate (TPA), whereas papillomas obtained by the same two‐stage protocol were distinctly heterogeneous with regard to the expression of this keratin. These findings were true for two different strains of mice (NMRI and Sencar). Papillomas collected from Sencar mice after 12 wk or from NMRI mice after 15 wk of promotion with TPA were either negative for K13 or elicited variable amounts of this keratin. In all cases of positive expression of K13 in tumors, as in normal stratified internal epithelia, both the keratin protein and its mRNA invariably occurred in the differentiating cell compartments. In contrast to what we found in internal stratified epithelia, however, K13 was expressed without its commonly encountered type II 57‐kDa partner, K4. Papillomas negative for the K13 protein were also devoid of K13 transcripts. This indicates that the aberrant K13 expression in tumors is regulated at the level of transcription. Our results suggest that K13 may provide a marker for malignant conversion in the mouse two‐stage skin carcinogenesis model and may be especially suited for studies of gene expression regulation.
Altered expression of acute‐phase reactants in mouse liver tumors
Authors: Liao Warren S. L. , Ma Kang‐Tao , Becker Frederick F. 
Published: February 2007

AbstractWe studied the expression of eight liver acute‐phase genes in spontaneous and diethylnitrosamine‐induced mouse liver tumors (MLTs) under basal and induced conditions. Primary spontaneous and chemically induced MLTs were used for RNA isolation and histopathologic analysis. In the noninduced state, all MLTs showed similar levels of mRNA for albumin, serum amyloid A, α1‐acid glycoprotein, haptoglobin, and α‐, β‐, and γ‐fibrinogens compared with control or background livers. The mRNA for the α‐major acute‐phase protein, however, was consistently elevated in both spontaneous and diethylnitrosamine‐induced MLTs.The expression of these acute‐phase reactants in 11 MLTs was examined following exposure of the mice to turpentine. The relative expression of these mRNAs in these MLTs varied widely compared with mRNA expression in controls. Though all MLTs expressed the same three species of fibrinogen mRNAs as did the controls, no MLT demonstrated downregulation of albumin mRNA levels, and only 1 of 11 MLTs showed a marginal increase in serum amyloid A mRNA levels. Synthesis of mRNA for α‐acid glycoprotein and haptoglobin was intermediate.The study of the response of MLTs to specific acute‐phase stimuli may make possible a better understanding of the basis for coordinated expression of acute‐phase reactants and of the variable phenotypes associated with cancers.
Malignant transformation of human bladder epithelial cells by DNA transfection with the v‐raf oncogene
Authors: Skouv Jan , Ottesen Svend , Mark George , Autrup Herman 
Published: February 2007

AbstractTransfection of the v‐raf oncogene into immortalized, nontumorigenic human bladder epithelial cells resulted in the isolation of two tumorigenic transformants. Both were identified as human and of the same origin as the parent cell line by human leukocyte antigen typing and Southern blot analysis. Both the primary tumorigenic transfectants and the cell lines established from the induced tumors expressed v‐raf mRNA and v‐raf protein. In both tumorigenic transformants the level of c‐myc mRNA was enhanced compared with that of the parent cell line.
Increased expression of glycolysis‐associated genes in oncogene‐transformed and growth‐accelerated states
Authors: Persons Derek A. , Schek Nancy , Hall Bruce Lee , Finn Olivera J. 
Published: February 2007

AbstractAn accelerated rate of glucose transport and catabolism is a common characteristic of cellular transformation. We have previously found elevated expression of the glycolytic enzyme glyceraldehyde‐3‐phosphate dehydrogenase (GAPDH) in human pancreatic and colonic adenocarcinomas (Schek et al.: Cancer Res 48:6354–6359, 1988). To investigate further the expression of this enzyme in the process of tumorigenesis, we examined GAPDH expression in a panel of oncogene‐transformed fibroblasts. Significant elevations of GAPDH mRNA and glucose transporter protein mRNA levels were observed in ras‐ and mos‐transformed NIH 3T3 cells, whereas little or no change was found in c‐src‐, v‐src‐, c‐myc‐, E1A‐, v‐fos‐, and PKC‐γ‐transfected cells. Furthermore, the level of GAPDH mRNA correlated with the transformed state in a series of ras‐transformed and revertant cell lines. Immunoblot analysis confirmed that GAPDH polypeptide was significantly elevated in the cell lines with elevated mRNA levels. Cell cycle analysis data suggested that the effect on GAPDH expression correlated with oncogene expression rather than cell growth fraction. These results suggest that altered GAPDH gene expression occurs during some growth deregulated states, and this, along with increased glucose transporter (and possibly other glycolytic enzyme) expression, is likely to contribute to the increased metabolic capacity of cells in these states.
Codon 61 Mutations in the c‐Harvey‐ras Gene in Mouse Skin Tumors Induced by 7,12‐Dimethylbenz[a]anthracene Plus Okadaic Acid Class Tumor Promoters
Authors: Fujiki Hirota , Suganuma Masami , Yoshizawa Shigeru , Kanazawa Hiroshi , Sugimura Takashi , Manam Sujata , Kahn Scott M. , Jiang Wei , Hoshina Sadayori , Weinstein I. Bernard 
Published: February 2007

AbstractThree okadaic acid class tumor promoters, okadaic acid, dinophysistoxin‐1, and calyculin A, have potent tumor‐promoting activity in two‐stage carcinogenesis experiments on mouse skin. DNA isolated from tumors induced by 7,12‐dimethylbenz[a]anthracene (DMBA) and each of these tumor promoters revealed the same mutation at the second nucleotide of codon 61 (CAA → CTA) in the c‐Ha‐ras gene, determined by the polymerase chain reaction procedure and DNA sequencing. Three potent 12‐O‐tetradecanoylphorbol‐13‐acetate (TPA)‐type tumor promoters, TPA, teleocidin, and aplysiatoxin, showed the same effects. These results provide strong evidence that this mutation in the c‐Ha‐ras gene is due to a direct effect of DMBA rather than a selective effect of specific tumor promoters.
Human cDNA‐Expressed Cytochrome P450 IA2: Mutagen Activation and Substrate Specificity
Authors: Aoyama Toshifumi , Gonzalez Frank J. , Gelboin Harry V. 
Published: February 2007

AbstractThe vaccinia virus cDNA expression system was used to produce human cytochrome P450 IA2 in a hepatoma cell line that is devoid of significant basal levels of P450. The expressed enzyme yielded a reduced carbon monoxide‐bound difference spectrum with a λmax of 449 nm. Catalytic activities and mutagen activation ability of the human enzyme were assessed and directly compared with results obtained with the orthologous mouse IA2, which was also expressed using vaccinia virus. Both the human and mouse enzymes were able to catalyze efficiently the p‐hydroxylation of aniline. Mouse IA2 also catalyzed ethoxyresorufin O‐deethylation, and its activity was sevenfold greater than expressed human IA2. The mouse and human enzymes also activated several promutagens and procarcinogens. Mouse IA2 was five‐ to sevenfold more active than the human enzyme for activation of the procarcinogens 2‐acetylaminofluorene and benzo[a]pyrene‐trans‐7,8‐dihydrodiol and the promutagens Glu‐P‐2 and Trp‐P‐1. Comparable activities were observed with 2‐aminoanthracene, 2‐aminofluorene, and Glu‐P‐1. These data demonstrate the utility of cDNA expression for examining the activities of human P450s and further suggest potentially important differences in catalytic activities of orthologous P450s found in different species.
Abolishment of c‐fos Inducibility in ras‐Transformed Mouse Osteoblast Cell Lines
Authors: Nose Kiyoshi , Itami Makiko , Satake Masanobu , Ito Yoshiaki , Kuroki Toshio 
Published: February 2007

AbstractProto‐oncogene c‐fos is induced by many types of cellular stimuli, such as 12‐O‐tetradecanoylphorbol‐13‐acetate (TPA), epidermal growth factor (EGF), serum (fetal bovine), calcium ionophore A23187, and dibutyryl cAMP (But2cAMP). In this study, c‐fos induction was abolished in ras‐transformed mouse osteoblast cells (MC3T3). Transformants of MC3T3 were isolated after transfection with Ki or Ha murine sarcoma virus DNA. All Ki‐ or Ha‐ras transformed MC3T3 clones examined showed exceedingly low levels of c‐fos induction by all inducers, as determined by the change in amounts of c‐fos mRNA or its product. Induction of other TPA‐responsive genes, such as metallothionein, was not altered in some ras‐transformed cells; c‐myc and c‐jun expression was constitutively high in all the ras‐transformed clones. Nuclear extracts and gel shift assay showed that the binding activity to c‐fos enhancer element (serum response element) was altered in ras‐transformed cells. These results indicate that transformation with ras oncogene induces modification of c‐fos enhancer binding factors and that this modification is one cause for the decrease in c‐fos induction.
Deletion of the c‐Ha‐ras‐1 Allele in Human Skin Cancers
Authors: Ananthaswamy Honnavara N. , Applegate Lee A. , Goldberg Leonard H. , Bales Elise S. 
Published: February 2007

AbstractPrevious studies have shown that c‐Ha‐ras‐1 and other genes located on the short arm of chromosome 11 are frequently lost in a number of human tumors. We investigated whether similar losses of the c‐Ha‐ras‐1 allele occurred in human squamous cell carcinomas (SCCs) and basal cell carcinomas (BCCs). DNAs were isolated from 35 pairs of skin tumors (25 BCCs and 10 SCCs) and matching normal skin from the same patients and analyzed for c‐Ha‐ras gene polymorphism by Southern blot hybridization. Sixteen BCC patients and 1 SCC patient were constitutionally heterozygous for the c‐Ha‐ras gene in their normal skin DNA. Of these 17 patients, five patients (four with BCC and one with SCC) (29%) showed loss of one of the c‐Ha‐ras alleles in their tumor DNA. One of the constitutionally heterozygous BCC patients exhibited deletion of the 6.6‐kb c‐Ha‐ras allele and an extra copy of the 7.8‐kb allele. In summary, loss of heterozygosity at the c‐Ha‐ras locus occurred frequently (29%) in the 17 human skin cancers studied. However, our finding that 90% of the patients with SCC, as opposed to 36% of the patients with BCC, had only one of the c‐Ha‐ras alleles in their normal skin tissue requires further study. Whether c‐Ha‐ras homozygosity has any bearing on genetic susceptibility to SCC remains to be established.
Amplification and Overexpression of c‐myc Proto‐Oncogene Correlate With the Loss of Glucocorticoid Dependence in Rodent Cells Transformed by Human Papillomavirus Type 16
Authors: Crook Tim , Banks Lawrence , Smith Katy , Crawford Lionel 
Published: February 2007

AbstractTransformation of baby mouse kidney epithelial cells by human papillomavirus (HPV) type 16 is dependent both upon the cooperating oncogene and on the hormonal conditions after transfection. With v‐fos as the oncogene, the transformed cells require glucocorticoid hormone, such as dexamethasone, for proliferation. This requirement is lost on continued passage of cell lines, and the cells become dexamethasone independent. Steroid‐independent cell lines are also produced by growth of the HPV16/v‐fos cells in 17 β‐estradiol following transfection, but cell lines produced in this manner showed no subsequent requirement for estradiol or dexamethasone. Expression of the c‐myc proto‐oncogene was measured in dexamethasone‐dependent and independent cell lines. Dexamethasone‐dependent cell lines all exhibited low level c‐myc expression, but this markedly increased in the cell lines that had become dexamethasone independent as a result of continued in vitro growth. The low level of c‐myc expression in some early passage dexamethasone‐dependent cell lines appears to be associated with rearrangement of the c‐myc locus, whereas late passage dexamethasone‐independent cell lines contain amplified c‐myc sequences. Dexamethasone‐independent cell lines derived by growth in 17 β‐estradiol showed higher levels of c‐myc expression, together with higher c‐myc copy number, than dexamethasone‐dependent lines. Taken together, these studies indicate that the steady‐state level of c‐myc expression affects the continued requirement of HPV 16‐transformed cells for dexamethasone.
Altered Growth Factor Dependence and Transforming Growth Factor Gene Expression in Transformed Rat Tracheal Epithelial Cells
Authors: Ferriola Patrice C. , Walker Cheryl , Robertson Alice T. , Earp H. Shelton , Rusnak David W. , Nettesheim Paul 
Published: February 2007

AbstractThe role of peptide growth factors in neoplastic progression of transformed rat tracheal epithelial (RTE) cells was assessed by examining growth factor requirements and expression of growth factor and growth factor receptor genes in normal and transformed RTE cells. Neoplastically transformed cell lines showed decreased requirements for bovine pituitary extract, insulin, and epidermal growth factor compared to normal primary RTE cells. Neoplastic RTE cell lines expressed significantly increased levels of transforming growth factor α (TGFα) RNA and secreted TGFα into the media, suggesting an autocrine role for this growth factor. Increased levels of TGFα RNA were also observed in the preneoplastic stages of the same cell lines, indicating that increased TGFα expression is an early event in the multistage process of neoplastic transformation of RTE cells. TGFβ transcripts were also overexpressed in neoplastically transformed cell lines. Our studies suggest that aberrant expression of growth factors may play an important role in the development and/or maintenance of the transformed phenotype in RTE cells.
Stable expression of human cytochrome P450IA2 cDNA in a human lymphoblastoid cell line: Role of the enzyme in the metabolic activation of aflatoxin B1
Authors: Crespi Charles L. , Steimel Dorothy T. , Aoyama Toshifumi , Gelboin Harry V. , Gonzalez Frank J. 
Published: February 2007

AbstractA human lymphoblastoid cell line stably expressing a human cytochrome P4501A2 cDNA was developed. This
recombinant cell line displayed P4501A2 protein and estradiol2‐hydroxylase activity, neither of which was detected
in the parental cell line. The recombinant cell line was also approximately 1000‐fold more sensitive t o the cyto‐
toxicity and mutagenicity of the carcinogenic mycotoxin aflatoxin B1 than was the parent cell line. The increase
in mutagenicity was supported by a corresponding increase in the level of aflatoxin B1 binding t o DNA in cells
expressing P4501A2 relative to control cells.
A common cellular pathway for v‐mos and v‐Ki‐ras is not required for v‐Ki‐ras‐induced tumorigenicity in a nonmalignant, v‐mos‐expressing revertant cell
Authors: Gerfaux Jacqueline , Sergiescu Dina , Hamelin Richard , Joret Anne‐Marie , Lallemand Christophe 
Published: February 2007

AbstractA revertant cell line was selected from Moloney sarcoma virus‐transformed BALB/c cells after long‐term treatment with type I interferon. Despite an actively transcribed and transferable v‐mos gene, these revertant cells were nontumorigenic in nude mice. The functionality of the mos protein was investigated, focusing on the α2(1) collagen promoter regulation, which is known to be affected by mos‐induced trans‐acting factors. Both in transient expression assays and after stable integration into the cellular genome, the transfected α2(1) collagen promoter fused to the cat reporter gene was activated in the revertant while being downregulated in the original transformed cells. In retransformation assays of the revertant by Moloney sarcoma virus strains homologous to the original transforming virus, no detectable change was noted in the in vitro phenotype or in tumorigenicity. These results reveal that the mos‐directed factors were no longer effective on their specific targets. Thus, the R.MSVIF cell could be either an oncoprotein‐deficient or a target‐related revertant. Attempts at retransformation with unrelated sarcoma viruses bearing v‐sis, v‐fms, or v‐fos oncogenes were also negative. In contrast, tumorigenicity was obtained with the unrelated Kirsten sarcoma virus without any change in the revertant morphology or collagen expression. These findings showed that the common pathway blocked by the reversion and shared by v‐mos and v‐ras was not required for ras‐induced tumorigenicity.
Decreased expression of the growth hormone receptor and growth hormone binding protein in rat liver nodules
Authors: Levinovitz Agneta , Husman Bolette , Eriksson Lennart C. , Norstedt Gunnar , Andersson Göran 
Published: February 2007

AbstractThe growth hormone receptor (GHR) and growth hormone‐binding protein (GH‐BP) expression were characterized in liver nodules and hepatomas from male Wistar rats. The mRNA levels of GHR and GH‐BP, studied by northern blot analysis and solution hybridization, were 35–50% (in nodules) and 2–6% (in hepatomas) of the level found in liver from untreated, age‐matched rats. The binding of 125I‐labeled human growth hormone to a low‐density membrane fraction (LDMF) containing Golgi and endosome membranes in the presence of excess ovine prolactin was 75–80% lower in nodules than in liver. When endogenous ligand was removed, the binding increased in nodules but not in liver. Affinity cross‐linking experiments revealed identical specific receptor‐binding protein complexes at Mr of 95,000, 55,000, and 43,000 in both nodules and liver, assuming stochiometric binding of ligand. The in vivo endocytosis of 125I‐labeled bovine growth hormone correlated with the level of GH binding and was thus reduced 75–80% in nodules, compared with liver. The level of insulin‐like growth factor‐I (IGF‐I) mRNA was reduced by 50% in nodules; however, GH administration resulted in a twofold induction of IGF‐I mRNA in both nodules and liver. It is concluded that the greater proportion of occupied GHR in nodules could result from an impaired dissociation of endogenous GH, which might explain the reduced GHR mRNA expression. Furthermore the low GHR mRNA expression may reflect a de‐differentiated phenotype in nodules.
Effects of protease inhibitors on c‐myc expression in normal and transformed C3H 10T1/2 cell lines
Authors: Chang Janice D. , Li Jih‐Heng , Billings Paul C. , Kennedy Ann R. 
Published: February 2007

AbstractIn the present study, the effect of protease inhibitors on c‐myc expression in normal and transformed C3H 10T1/2 cells was examined. Steady‐state c‐myc RNA levels were reduced in normal proliferating C3H 10T1/2 cells grown in medium containing antipain, leupeptin, and Bowman Birk inhibitor (BBI). These protease inhibitors have been shown previously to suppress transformation yields in carcinogen‐exposed cells. A lesser reduction in c‐myc RNA levels was observed when cells were grown in the presence of protease inhibitors that do not suppress carcinogenesis and when transformed C3H 10T1/2 cell populations were grown in the presence of the anticarcinogenic protease inhibitors. Studies to determine the effects of antipain on the stability of the c‐myc message and on c‐myc transcription rates were also performed. The half‐life of the c‐myc message increased from 10 to 40 min when cells were grown in antipain; cycloheximide further stabilized the c‐myc message. Interestingly, nuclear run‐off experiments showed that antipain had no effect on c‐myc transcription rates. These data suggest that proteases may be involved in the regulation of c‐myc RNA expression in normal C3H 10T1/2 cells, possibly by a posttranscriptional mechanism.