bluuebunny/crossref_metadata_2025_split huggingface dataset:
Functional Analysis of PIK3CA Gene Mutations in Human Colorectal Cancer
Authors: Ikenoue Tsuneo , Kanai Fumihiko , Hikiba Yohko , Obata Toshiyuki , Tanaka Yasuo , Imamura Jun , Ohta Miki , Jazag Amarsanaa , Guleng Bayasi , Tateishi Keisuke , Asaoka Yoshinari , Matsumura Masayuki , Kawabe Takao , Omata Masao 
Published: September 2005

Abstract
Mutations in the PIK3CA gene, which encodes the p110α catalytic subunit of phosphatidylinositol 3-kinase (PI3K), have been reported in human cancers, including colorectal cancer. Most of the mutations cluster at hotspots within the helical and kinase domains. Whereas H1047R, one of the hotspot mutants, is reported to have elevated lipid kinase activity, the functional consequences of other mutations have not been examined. In this study, we examined the effects of colon cancer–associated PIK3CA mutations on the lipid kinase activity in vitro, activation of the downstream targets Akt and p70S6K in vivo and NIH 3T3-transforming ability. Of eight mutations examined, all showed increased lipid kinase activity compared with wild-type p110α. All the mutants strongly activated Akt and p70S6K compared with wild-type p110α as determined by immunoblotting using phospho-specific antibodies. These mutants also induced morphologic changes, loss of contact inhibition, and anchorage-independent growth of NIH 3T3 cells. The hotspot mutations examined in this study, E542K, E545K, and H1047R, all had high enzymatic and transforming activities. These results show that almost all the colon cancer–associated PIK3CA mutations are functionally active so that they are likely to be involved in carcinogenesis.
T25 Repeat in the 3′ Untranslated Region of the CASP2 Gene: A Sensitive and Specific Marker for Microsatellite Instability in Colorectal Cancer
Authors: Findeisen Peter , Kloor Matthias , Merx Sabine , Sutter Christian , Woerner Stefan M. , Dostmann Nicole , Benner Axel , Dondog Bolormaa , Pawlita Michael , Dippold Wolfgang , Wagner Rudolf , Gebert Johannes , von Knebel Doeberitz Magnus 
Published: September 2005

Abstract
DNA mismatch repair deficiency is observed in about 10% to 15% of all colorectal carcinomas and in up to 90% of hereditary nonpolyposis colorectal cancer (HNPCC) patients. Tumors with mismatch repair defects acquire mutations in short repetitive DNA sequences, a phenomenon termed high-level microsatellite instability (MSI-H). The diagnosis of MSI-H in colon cancer is of increasing relevance, because MSI-H is an independent prognostic factor in colorectal cancer, seems to influence the efficacy of adjuvant chemotherapy, and is the most important molecular screening tool to identify HNPCC patients. To make MSI typing feasible for the routine pathology laboratory, highly reproducible and cost effective laboratory tests are required. Here, we describe a novel T25 mononucleotide marker in the 3′untranslated region of the CASP2 gene (CAT25) that displayed a quasimonomorphic repeat pattern in normal tissue of 200 unrelated individuals of Caucasian origin. In addition, CAT25 was monomorphic also in all tested donors of African and Asian origin (n = 102 and n = 79, respectively) and thus differs from the most commonly used markers BAT25 and BAT26. Without the analysis of corresponding normal tissue, CAT25 correctly detected 56 of 57 colorectal cancer specimens classified as MSI-H by using the standard National Cancer Institute/International Collaborative Group-HNPCC marker panel. Combined with the standard markers BAT25 and BAT26 in a multiplex PCR, all MSI-H colorectal cancer samples were typed correctly. No false-positive results were obtained in 60 non-MSI-H control colorectal cancer specimens. These data suggest that CAT25 should be included into novel marker panels for microsatellite testing thus allowing for a significant reduction of the complexity and costs of MSI typing. Moreover, CAT25 represents a highly promising marker for early detection of colorectal cancer in HNPCC germ line mutation carriers.
Susceptibility of Cholangiocarcinoma Cells to Parthenolide-Induced Apoptosis
Authors: Kim Jong-Hyun , Liu Lan , Lee Seung-Ok , Kim Yong-Tae , You Kyung-Ran , Kim Dae-Ghon 
Published: September 2005

Abstract
Cholangiocarcinomas are intrahepatic bile duct carcinomas that are known to have a poor prognosis. Sesquiterpene lactone parthenolide, which is the principal active component in medicinal plants, has been used to treat tumors. Parthenolide effectively induced apoptosis in all four cholangiocarcinoma cell lines in a dose-dependent manner. However, the sarcomatous SCK cells were more sensitive to parthenolide than the other adenomatous cholangiocarcinoma cells. Therefore, this study investigated whether or not the expression of p53, the Fas/Fas ligand (FasL), Bcl-2/Bcl-XL determines the enhanced drug susceptibility of SCK cells. The results showed that Bcl-2 family molecules, such as Bid, Bak, and Bax, are involved in the parthenolide-induced apoptosis and that the defective expression of Bcl-XL might contribute to the higher parthenolide sensitivity in the SCK cells than in the other adenomatous cholangiocarcinoma cells. SCK cells, which stably express Bcl-XL, were resistant to parthenolide, whereas Bcl-XL-positive Choi-CK cells transfected with the antisense Bcl-XL showed a higher parthenolide sensitivity than the vector control cells. Molecular dissection revealed that Bcl-XL inhibited the translocation of Bax to the mitochondria, decreased the generation of intracellular reactive oxygen species, reduced the mitochondrial transmembrane potential (ΔΨm), decreased the release of cytochrome c, decreased the cleavage of poly(ADP-ribose) polymerase, and eventually inhibited apoptotic cell death. These results suggest that parthenolide effectively induces oxidative stress-mediated apoptosis, and that the susceptibility to parthenolide in cholangiocarcinoma cells might be modulated by Bcl-XL expression in association with Bax translocation to the mitochondria.
Inhibition of the DNA-Dependent Protein Kinase Catalytic Subunit Radiosensitizes Malignant Glioma Cells by Inducing Autophagy
Authors: Daido Shigeru , Yamamoto Akitsugu , Fujiwara Keishi , Sawaya Raymond , Kondo Seiji , Kondo Yasuko 
Published: September 2005

Abstract
DNA-dependent protein kinase (DNA-PK) plays a major role in the repair of DNA double-strand breaks induced by ionizing radiation (IR). Lack of DNA-PK causes defective DNA double-strand break repair and radiosensitization. In general, the cell death induced by IR is considered to be apoptotic. On the other hand, nonapoptotic cell death, autophagy, has recently attracted attention as a novel response of cancer cells to chemotherapy and IR. Autophagy is a protein degradation system characterized by a prominent formation of double-membrane vesicles in the cytoplasm. Little is known, however, regarding the relationship between DNA-PK and IR-induced autophagy. In the present study, we used human malignant glioma M059J and M059K cells to investigate the role of DNA-PK in IR-induced apoptotic and autophagic cell death. Low-dose IR induced massive autophagic cell death in M059J cells that lack the catalytic subunit of DNA-PK (DNA-PKcs). Most M059K cells, the counterpart of M059J cells in which DNA-PKcs are expressed at normal levels, survived, and proliferated although a small portion of the cells underwent apoptosis. Low-dose IR inhibited the phosphorylation of p70S6K, a molecule downstream of the mammalian target of rapamycin associated with autophagy in M059J cells but not in M059K cells. The treatment of M059K cells with antisense oligonucleotides against DNA-PKcs caused radiation-induced autophagy and radiosensitized the cells. Furthermore, antisense oligonucleotides against DNA-PKcs radiosensitized other malignant glioma cell lines with DNA-PK activity, U373-MG and T98G, by inducing autophagy. The specific inhibition of DNA-PKcs may be promising as a new therapy to radiosensitize malignant glioma cells by inducing autophagy.
High-Resolution Genome-Wide Mapping of Genetic Alterations in Human Glial Brain Tumors
Authors: Bredel Markus , Bredel Claudia , Juric Dejan , Harsh Griffith R. , Vogel Hannes , Recht Lawrence D. , Sikic Branimir I. 
Published: September 2005

Abstract
High-resolution genome-wide mapping of exact boundaries of chromosomal alterations should facilitate the localization and identification of genes involved in gliomagenesis and may characterize genetic subgroups of glial brain tumors. We have done such mapping using cDNA microarray-based comparative genomic hybridization technology to profile copy number alterations across 42,000 mapped human cDNA clones, in a series of 54 gliomas of varying histogenesis and tumor grade. This gene-by-gene approach permitted the precise sizing of critical amplicons and deletions and the detection of multiple new genetic aberrations. It has also revealed recurrent patterns of occurrence of distinct chromosomal aberrations as well as their interrelationships and showed that gliomas can be clustered into distinct genetic subgroups. A subset of detected alterations was shown predominantly associated with either astrocytic or oligodendrocytic tumor phenotype. Finally, five novel minimally deleted regions were identified in a subset of tumors, containing putative candidate tumor suppressor genes (TOPORS, FANCG, RAD51, TP53BP1, and BIK) that could have a role in gliomagenesis.
Somatic Mutations of the HER2 Kinase Domain in Lung Adenocarcinomas
Authors: Shigematsu Hisayuki , Takahashi Takao , Nomura Masaharu , Majmudar Kuntal , Suzuki Makoto , Lee Huei , Wistuba Ignacio I. , Fong Kwun M. , Toyooka Shinichi , Shimizu Nobuyoshi , Fujisawa Takehiko , Minna John D. , Gazdar Adi F. 
Published: September 2005

Abstract
Mutations in the epidermal growth factor receptor gene (EGFR) in lung cancers predict for sensitivity to EGFR kinase inhibitors. HER2 (also known as NEU, EGFR2, or ERBB2) is a member of the EGFR family of receptor tyrosine kinases and plays important roles in the pathogenesis of certain human cancers, and mutations have recently been reported in lung cancers. We sequenced the tyrosine kinase domain of HER2 in 671 primary non–small cell lung cancers (NSCLC), 80 NSCLC cell lines, and 55 SCLCs and other neuroendocrine lung tumors as well as 85 other epithelial cancers (breast, bladder, prostate, and colorectal cancers) and compared the mutational status with clinicopathologic features and the presence of EGFR or KRAS mutations. HER2 mutations were present in 1.6% (11 of 671) of NSCLC and were absent in other types of cancers. Only one adenocarcinoma cell line (NCI-H1781) had a mutation. All HER2 mutations were in-frame insertions in exon 20 and target the identical corresponding region as did EGFR insertions. HER2 mutations were significantly more frequent in never smokers (3.2%, 8 of 248; P = 0.02) and adenocarcinoma histology (2.8%, 11 of 394; P = 0.003). In 394 adenocarcinoma cases, HER2 mutations preferentially targeted Oriental ethnicity (3.9%) compared with other ethnicities (0.7%), female gender (3.6%) compared with male gender (1.9%) and never smokers (4.1%) compared with smokers (1.4%). Mutations in EGFR, HER2, and KRAS genes were never present together in individual tumors and cell lines. The remarkable similarities of mutations in EGFR and HER2 genes involving tumor type and subtype, mutation type, gene location, and specific patient subpopulations targeted are unprecedented and suggest similar etiologic factors. EGFR, HER2, and KRAS mutations are mutually exclusive, suggesting different pathways to lung cancer in smokers and never smokers.
Gene Amplification Is a Mechanism of Six1 Overexpression in Breast Cancer
Authors: Reichenberger Kelly J. , Coletta Ricardo D. , Schulte Aline P. , Varella-Garcia Marileila , Ford Heide L. 
Published: September 2005

Abstract
The Six1 homeoprotein plays a critical role in expanding progenitor populations during normal development via its stimulation of proliferation and inhibition of apoptosis. Overexpression of Six1 is observed in several tumor types, suggesting that when expressed out of context, Six1 may contribute to tumorigenesis by reinstating properties normally conveyed on developing cells. Indeed, Six1 contributes to tumor cell proliferation both in breast cancer and in rhabdomyosarcomas, in which it is also implicated in metastasis. Whereas Six1 overexpression has been reported in several tumor types, the mechanism responsible for its overexpression has not previously been examined. Here we show that a change in gene dosage may contribute to Six1 mRNA overexpression. Significant Six1 gene amplification and overrepresentation occurs in numerous breast cancer cell lines as compared with normal mammary epithelial cells, and the changes in gene dosage correlate with increased Six1 mRNA levels. Of 214 human infiltrating ductal breast carcinomas examined for Six1 gene dosage, 4.7% show Six1 amplification/overrepresentation, and tumors that exhibit an increase in Six1 gene dosage overexpress Six1 mRNA. These data implicate Six1 gene amplification/overrepresentation as a mechanism of Six1 mRNA overexpression in human breast cancer.
Magnetic Resonance Angiography Visualization of Abnormal Tumor Vasculature in Genetically Engineered Mice
Authors: Brubaker Lauren M. , Bullitt Elizabeth , Yin Chaoying , Van Dyke Terry , Lin Weili 
Published: September 2005

AbstractPrevious research on the vasculature of tumor-bearing animals has focused upon the microvasculature. Magnetic resonance angiography (MRA) offers a noninvasive, complementary approach that provides information about larger vessels. Quantitative analysis of MRA images of spontaneous preclinical tumor models has not been previously reported. Eleven TgT121;p53+/− mice, which invariably develop choroid plexus carcinoma (CPC), and nine age-matched healthy controls were imaged using T1, T2, and a high-resolution three-dimensional time-of-flight MRA sequences at 3 T. Tumors and vessels were segmented to determine tumor volume and vascular attributes, including number of terminal branches, vessel count, and the average vessel radii of MRA-visible vessels within the tumor. Differences in the vasculature between tumor-bearing animals and healthy controls were analyzed statistically. Although the spatial resolution of MRA prohibits visualization of capillaries, a high density of intratumor blood vessels was visualized in CPC mice. A significant increase in terminal branch count and vessel count, but not average vessel radius, was observed in CPCs when compared with normal controls. Both terminal branch count and vessel count were highly correlated with tumor volume. This study represents the first MRA analysis of a spontaneous preclinical brain tumor model. Although the spatial resolution of MRA is less than histologic analysis, MRA-obtained vascular attributes provide useful information with full brain coverage. We show that consistent tumor vasculature properties can be determined by MRA. Such methods are critical for developing preclinical therapeutic testing and will help guide the development of human brain tumor analyses.
Synthetic Anticancer Gene Medicine Exploits Intrinsic Antitumor Activity of Cationic Vector to Cure Established Tumors
Authors: Dufès Christine , Keith W. Nicol , Bilsland Alan , Proutski Irina , Uchegbu Ijeoma F. , Schätzlein Andreas G. 
Published: September 2005

Abstract
The systemic delivery of genetic therapies required for the treatment of inaccessible tumors and metastases remains a challenge despite the development of various viral and synthetic vector systems. Here we show that a synthetic vector system based on polypropylenimine dendrimers has the desired properties of a systemic delivery vehicle and mediates efficient transgene expression in tumors after i.v. administration. The systemic tumor necrosis factor α (TNFα) gene therapy was efficacious in the experimental treatment of established A431 epidermoid carcinoma, C33a cervix carcinoma, and LS174T colorectal adenocarcinoma. Specifically, the systemic injection of dendrimer nanoparticles containing a TNFα expression plasmid regulated by telomerase gene promoters (hTR and hTERT) leads to transgene expression, regression of remote xenograft murine tumors, and long-term survival of up to 100% of the animals. Interestingly, these dendrimers and, to a lesser extent, other common polymeric transfection agents also exhibit plasmid-independent antitumor activity, ranging from pronounced growth retardation to complete tumor regression. The genetic therapy as well as treatment with dendrimer alone was well tolerated with no apparent signs of toxicity in the animals. The combination of intrinsic dendrimer activity and transcriptionally targeted TNFα when complexed was significantly more potent than either treatment alone or when both were administered in sequence. The combination of pharmacologically active synthetic transfection agent and transcriptionally targeted antitumor gene creates an efficacious gene medicine for the systemic treatment of experimental solid tumors.
Targeted Biallelic Inactivation of Pten in the Mouse Prostate Leads to Prostate Cancer Accompanied by Increased Epithelial Cell Proliferation but not by Reduced Apoptosis
Authors: Ma Xiaoqian , Ziel-van der Made Angelique C. , Autar Binha , van der Korput Hetty A. , Vermeij Marcel , van Duijn Petra , Cleutjens Kitty B. , de Krijger Ronald , Krimpenfort Paul , Berns Anton , van der Kwast Theo H. , Trapman Jan 
Published: September 2005

Abstract
The PTEN tumor suppressor gene is frequently inactivated in human tumors, including prostate cancer. Based on the Cre/loxP system, we generated a novel mouse prostate cancer model by targeted inactivation of the Pten gene. In this model, Cre recombinase was expressed under the control of the prostate-specific antigen (PSA) promoter. Conditional biallelic and monoallelic Pten knock-out mice were viable and Pten recombination was prostate-specific. Mouse cohorts were systematically characterized at 4 to 5, 7 to 9, and 10 to 14 months. A slightly increased proliferation rate of epithelial cells was observed in all prostate lobes of monoallelic Pten knock-out mice (PSA-Cre;Pten-loxP/+), but minimal pathologic changes were detected. All homozygous knock-out mice (PSA-Cre;Pten-loxP/loxP) showed an increased size of the luminal epithelial cells, large areas of hyperplasia, focal prostate intraepithelial neoplasia lesions and an increased prostate weight at 4 to 5 months. More extensive prostate intraepithelial neoplasia and focal microinvasion occurred at 7 to 9 months; invasive prostate carcinoma was detected in all male PSA-Cre;Pten-loxP/loxP mice at 10 to 14 months. At 15 to 16 months, a rare lymph node metastasis was found. In hyperplastic cells and in tumor cells, the expression of phospho-AKT was up-regulated. In hyperplastic and tumor cells, expression of luminal epithelial cell cytokeratins was up-regulated; tumor cells were negative for basal epithelial cell cytokeratins. Androgen receptor expression remained detectable at all stages of tumor development. The up-regulation of phospho-AKT correlated with an increased proliferation rate of the epithelial cells, but not with a reduced apoptosis.
Observation of Incipient Tumor Angiogenesis That Is Independent of Hypoxia and Hypoxia Inducible Factor-1 Activation
Authors: Cao Yiting , Li Chuan-Yuan , Moeller Benjamin J. , Yu Daohai , Zhao Yulin , Dreher Matthew R. , Shan Siqing , Dewhirst Mark W. 
Published: September 2005

Abstract
It is well established that hypoxia potently stimulates tumor angiogenesis by activating hypoxia inducible factor-1 (HIF-1)–induced proangiogenic factors, such as vascular endothelial growth factor. However, very little is known about the role of hypoxia in incipient angiogenesis in avascular tumors during their early stages of growth. To noninvasively investigate the functional significance of hypoxia and HIF-1 activation in incipient tumor angiogenesis, we genetically engineered HCT116 human colon carcinoma cells and 4T1 mouse mammary carcinoma cells with constitutively expressed red fluorescence protein as a tumor marker and green fluorescence protein (GFP) as a reporter for hypoxia and HIF-1 activation. The accuracy of GFP fluorescence in reporting hypoxia was confirmed by flow cytometry analysis and by immunohistochemical comparison with pimonidazole, a well-established hypoxia marker drug. Mouse dorsal skin-fold window chambers showed that incipient angiogenesis preceded a detectable level of hypoxia. The detectable levels of hypoxia were spatially and temporally related with more intensive secondary angiogenesis following the initial onset of new vessel formation. Selective killing of hypoxic cells by tirapazamine efficiently eliminated or delayed the detection of hypoxic cells, but it did not significantly delay the onset of incipient angiogenesis. These findings provide the first in vivo evidence that incipient tumor angiogenesis may not depend on hypoxia or HIF-1 activation. This is in contrast to the clear role of hypoxia in driving angiogenesis once initial tumor microvessel formation has occurred.
Tumor-Associated NH2-Terminal Fragments Are the Most Stable Part of the Adenomatous Polyposis Coli Protein and Can Be Regulated by Interactions with COOH-Terminal Domains
Authors: Li Zhuoyu , Näthke Inke S. 
Published: September 2005

Abstract
Truncation mutations in the adenomatous polyposis coli (APC) gene are responsible for familial and sporadic colorectal cancer. APC is a large, multifunctional protein involved in cell migration, proliferation, and differentiation. Dominant effects that have been attributed to the NH2-terminal fragments of APC expressed in tumors may result from loss of functions due to lack of COOH-terminal regions or gain of functions due to fewer regulatory interactions. Resolving this issue and determining how structural changes contribute to the multiple functions of the APC protein requires knowledge about the structural organization of the APC molecule. To this end, we used limited proteolysis to distinguish regions of the molecule with limited structure from those that form well-folded domains. We discovered that the NH2-terminal region of APC was most resistant to proteolytic degradation, whereas middle and COOH-terminal regions were significantly more sensitive. Binding of APC to microtubules protected COOH-terminal regions of APC against proteolysis, consistent with the idea that this region of the molecule becomes ordered when bound to microtubules. Furthermore, interactions between the NH2- and COOH-terminal domains of APC were identified in vitro and in vivo, suggesting that NH2-terminal fragments of APC may be regulated by interactions with COOH-terminal domains. Indeed, expressing COOH-terminal APC fragments in tumor cells resulted in changes in the protein interactions of endogenous NH2-terminal fragments in these cells. Thus, the dominant function of NH2-terminal APC fragments found in tumor cells could be explained by loss of this regulation in tumors where COOH-terminal domains are missing.