bluuebunny/crossref_metadata_2025 huggingface dataset:
Data from Visualization of Hypoxia in Microscopic Tumors by Immunofluorescent Microscopy
Authors: Li Xiao-Feng , Carlin Sean , Urano Muneyasu , Russell James , Ling C. Clifton , O'Donoghue Joseph A.
Published: March 2023

Abstract
Tumor hypoxia is commonly observed in primary solid malignancies but the hypoxic status of subclinical micrometastatic disease is largely unknown. The distribution of hypoxia in microscopic tumors was studied in animal models of disseminated peritoneal disease and intradermal (i.d.) growing tumors. Tumors derived from human colorectal adenocarcinoma cell lines HT29 and HCT-8 ranged in size from a few hundred microns to several millimeters in diameter. Hypoxia was detected by immunofluorescent visualization of pimonidazole and the hypoxia-regulated protein carbonic anhydrase 9. Tumor blood perfusion, cellular proliferation, and vascularity were visualized using Hoechst 33342, bromodeoxyuridine, and CD31 staining, respectively. In general, tumors of <1 mm diameter were intensely hypoxic, poorly perfused, and possessed little to no vasculature. Larger tumors (∼1–4 mm diameter) were well perfused with widespread vasculature and were not significantly hypoxic. Patterns of hypoxia in disseminated peritoneal tumors and i.d. tumors were similar. Levels of hypoxia in microscopic peritoneal tumors were reduced by carbogen breathing. Peritoneal and i.d. tumor models are suitable for studying hypoxia in microscopic tumors. If the patterns of tumor hypoxia in human patients are similar to those observed in these animal experiments, then the efficacy of systemic treatments of micrometastatic disease may be compromised by hypoxic resistance. [Cancer Res 2007;67(16):7646–52]
Data from Systemic Treatment with the Antidiabetic Drug Metformin Selectively Impairs p53-Deficient Tumor Cell Growth
Authors: Buzzai Monica , Jones Russell G. , Amaravadi Ravi K. , Lum Julian J. , DeBerardinis Ralph J. , Zhao Fangping , Viollet Benoit , Thompson Craig B.
Published: March 2023

Abstract
The effect of the antidiabetic drug metformin on tumor growth was investigated using the paired isogenic colon cancer cell lines HCT116 p53+/+ and HCT116 p53−/−. Treatment with metformin selectively suppressed the tumor growth of HCT116 p53−/− xenografts. Following treatment with metformin, we detected increased apoptosis in p53−/− tumor sections and an enhanced susceptibility of p53−/− cells to undergo apoptosis in vitro when subject to nutrient deprivation. Metformin is proposed to function in diabetes treatment as an indirect activator of AMP-activated protein kinase (AMPK). Treatment with AICAR, another AMPK activator, also showed a selective ability to inhibit p53−/− tumor growth in vivo. In the presence of either of the two drugs, HCT116 p53+/+ cells, but not HCT116 p53−/− cells, activated autophagy. A similar p53-dependent induction of autophagy was observed when nontransformed mouse embryo fibroblasts were treated. Treatment with either metformin or AICAR also led to enhanced fatty acid β-oxidation in p53+/+ MEFs, but not in p53−/− MEFs. However, the magnitude of induction was significantly lower in metformin-treated cells, as metformin treatment also suppressed mitochondrial electron transport. Metformin-treated cells compensated for this suppression of oxidative phosphorylation by increasing their rate of glycolysis in a p53-dependent manner. Together, these data suggest that metformin treatment forces a metabolic conversion that p53−/− cells are unable to execute. Thus, metformin is selectively toxic to p53-deficient cells and provides a potential mechanism for the reduced incidence of tumors observed in patients being treated with metformin. [Cancer Res 2007;67(14):6745–52]
Data from Bmi-1 Cooperates with H-Ras to Transform Human Mammary Epithelial Cells via Dysregulation of Multiple Growth-Regulatory Pathways
Authors: Datta Sonal , Hoenerhoff Mark J. , Bommi Prashant , Sainger Rachana , Guo Wei-Jian , Dimri Manjari , Band Hamid , Band Vimla , Green Jeffrey E. , Dimri Goberdhan P.
Published: March 2023

Abstract
Elevated expression of Bmi-1 is associated with many cancers, including breast cancer. Here, we examined the oncogenic potential of Bmi-1 in MCF10A cells, a spontaneously immortalized, nontransformed strain of human mammary epithelial cells (HMEC). Bmi-1 overexpression alone in MCF10A cells did not result in oncogenic transformation. However, Bmi-1 co-overexpression with activated H-Ras (RasG12V) resulted in efficient transformation of MCF10A cells in vitro. Although early-passage H-Ras–expressing MCF10A cells were not transformed, late-passage H-Ras–expressing cells exhibited features of transformation in vitro. Early- and late-passage H-Ras–expressing cells also differed in levels of expression of H-Ras and Ki-67, a marker of proliferation. Subsets of early-passage H-Ras–expressing cells exhibited high Ras expression and were negative for Ki-67, whereas most late-passage H-Ras–expressing cells expressed low levels of Ras and were Ki-67 positive. Injection of late-passage H-Ras–expressing cells in severe combined immunodeficient mice formed carcinomas with leiomatous, hemangiomatous, and mast cell components; these tumors were quite distinct from those induced by late-passage cells co-overexpressing Bmi-1 and H-Ras, which formed poorly differentiated carcinomas with spindle cell features. Bmi-1 and H-Ras co-overexpression in MCF10A cells also induced features of epithelial-to-mesenchymal transition. Importantly, Bmi-1 inhibited senescence and permitted proliferation of cells expressing high levels of Ras. Examination of various growth-regulatory pathways suggested that Bmi-1 overexpression together with H-Ras promotes HMEC transformation and breast oncogenesis by deregulation of multiple growth-regulatory pathways by p16INK4a-independent mechanisms. [Cancer Res 2007;67(21):10286–95]
Data from Maternal Embryonic Leucine Zipper Kinase/Murine Protein Serine-Threonine Kinase 38 Is a Promising Therapeutic Target for Multiple Cancers
Authors: Gray Daniel , Jubb Adrian M. , Hogue Deborah , Dowd Patrick , Kljavin Noelyn , Yi Sothy , Bai Wei , Frantz Gretchen , Zhang Zemin , Koeppen Hartmut , de Sauvage Frederic J. , Davis David P.
Published: March 2023

Abstract
To identify genes that could serve as targets for novel cancer therapeutics, we used a bioinformatic analysis of microarray data comparing gene expression between normal and tumor-derived primary human tissues. From this approach, we have found that maternal embryonic leucine zipper kinase (Melk), a member of the AMP serine/threonine kinase family, exhibits multiple features consistent with the potential utility of this gene as an anticancer target. An oligonucleotide microarray analysis of multiple human tumor samples and cell lines suggests that Melk expression is frequently elevated in cancer relative to normal tissues, a pattern confirmed by quantitative reverse transcription-PCR and Western blotting of selected primary tumor samples. In situ hybridization localized Melk expression to malignant epithelial cells in 96%, 23%, and 13% of colorectal, lung, and ovarian tissue tumor samples, respectively. Expression of this gene is also elevated in spontaneous tumors derived from the ApcMin and Apc1638N murine models of intestinal tumorigenesis. To begin addressing whether Melk is relevant for tumorigenesis, RNA interference–mediated silencing within human and murine tumor cell lines was done. We show that Melk knockdown decreases proliferation and anchorage-independent growth in vitro as well as tumor growth in a xenograft model. Together, these results suggest that Melk may provide a growth advantage for neoplastic cells and, therefore, inactivation may be therapeutically beneficial.
Data from Metastasis-Associated Protein 1 Transgenic Mice: A New Model of Spontaneous B-Cell Lymphomas
Authors: Bagheri-Yarmand Rozita , Balasenthil Seetharaman , Gururaj Anupama E. , Talukder Amjad H. , Wang Yui-Hsi , Lee Ju Han , Kim Young Sik , Zhang Xinaglan , Jones Daniel M. , Medeiros L. Jeffrey , Stephens L. Clifton , Liu Yong-Jun , Lee Norman , Kim Insun , Kumar Rakesh
Published: March 2023

Abstract
Metastasis-associated protein 1 (MTA1), a component of the nuclear remodeling complex and the founding homologue of the MTA family, has been implicated in metastasis, but definitive causative evidence in an animal model system is currently lacking. Here, we show that MTA1 overexpression in transgenic mice is accompanied by a high incidence of spontaneous B cell lymphomas including diffuse large B cell lymphomas (DLBCL). Lymphocytes and lymphoma cells from MTA1-TG mice are hyperproliferative. Lymphomas were transplantable and of clonal origin and were characterized by down-regulation of p27Kip1 as well as up-regulation of Bcl2 and cyclin D1. The significance of these murine studies was established by evidence showing a widespread up-regulation of MTA1 in DLBCL from humans. These findings reveal a previously unrecognized role for the MTA1 pathway in the development of spontaneous B cell lymphomas, and offer a potential therapeutic target in B cell lymphomas. These observations suggest that MTA1-TG mice represent a new model of spontaneous DLBCL associated with high tumor incidence and could be used for therapeutic intervention studies. [Cancer Res 2007;67(15):7062–7]
Data from TrkC Binds to the Bone Morphogenetic Protein Type II Receptor to Suppress Bone Morphogenetic Protein Signaling
Authors: Jin Wook , Yun Chohee , Kim Hae-Suk , Kim Seong-Jin
Published: March 2023

Abstract
TrkC, a member of the tropomyosin-related kinase (Trk) family of neurotrophin receptors, is implicated in the growth and survival of human cancer tissues. TrkC is also a potent oncoprotein expressed in tumors derived from multiple cell lineages, and functions as an active protein tyrosine kinase by neurotrophin-3 (NT-3). We previously reported that TrkC plays an essential role in tumor growth and metastasis in a murine cancer cell line. Here, we report that expression of TrkC suppresses bone morphogenetic protein 2 (BMP-2)–induced Smad1 phosphorylation and transcriptional activation. In the highly metastatic CT26 murine colon cancer cell line, which expresses endogenous TrkC, silencing TrkC expression by small interfering RNA significantly enhanced BMP-2–induced Smad1 phosphorylation and restored BMP-2 growth inhibitory activity. In contrast, expression of TrkC in RIE-1 cells, in which TrkC is not expressed, completely suppressed BMP-2 transcriptional activation. Furthermore, we showed that TrkC directly binds to the BMP type II receptor (BMPRII), thereby preventing it from interacting with the BMPRI. This activity requires a functional TrkC protein tyrosine kinase, and the BMPRII seems to be a direct target of TrkC. Our findings provide evidence for a previously unknown mechanism by which TrkC, a neuronal receptor, can block BMP tumor-suppressor activity. [Cancer Res 2007;67(20):9869–77]
Data from Honokiol Induces a Necrotic Cell Death through the Mitochondrial Permeability Transition Pore
Authors: Li Ling , Han Weidong , Gu Ying , Qiu Shuang , Lu Qinghua , Jin Jie , Luo Jianhong , Hu Xun
Published: March 2023

Abstract
Previous reports have shown that honokiol induces apoptosis in numerous cancer cell lines and showed preclinical efficacies against apoptosis-resistant B-cell chronic lymphocytic leukemia and multiple myeloma cells from relapse-refractory patients. Here, we show that honokiol can induce a cell death distinct from apoptosis in HL60, MCF-7, and HEK293 cell lines. The death was characterized by a rapid loss of integrity of plasma membrane without externalization of phosphatidyl serine. The broad caspase inhibitor z-VAD-fmk failed to prevent this cell death. Consistently, caspase activation and DNA laddering were not observed. The death was paralleled by a rapid loss of mitochondrial membrane potential, which was mechanistically associated with the mitochondrial permeability transition pore regulated by cyclophilin D (CypD) based on the following evidence: (a) cyclosporin A, an inhibitor of CypD (an essential component of the mitochondrial permeability transition pore), effectively prevented honokiol-induced cell death and loss of mitochondrial membrane potential; (b) inhibition of CypD by RNA interference blocked honokiol-induced cell death; (c) CypD up-regulated by honokiol was correlated with the death rates in HL60, but not in K562 cells, which underwent apoptosis after being exposed to honokiol. We further showed that honokiol induced a CypD-regulated death in primary human acute myelogenous leukemia cells, overcame Bcl-2 and Bcl-XL–mediated apoptotic resistance, and was effective against HL60 cells in a pilot in vivo study. To the best of our knowledge, this is the first report to document an induction of mitochondrial permeability transition pore–associated cell death by honokiol. [Cancer Res 2007;67(10):4894–903]
Data from Effects of Tetramethoxystilbene on Hormone-Resistant Breast Cancer Cells: Biological and Biochemical Mechanisms of Action
Authors: Park Hoyong , Aiyar Sarah E. , Fan Ping , Wang Jiping , Yue Wei , Okouneva Tatiana , Cox Corey , Jordan Mary Ann , Demers Laurence , Cho Hyungjun , Kim Sanghee , Song Robert X.-D. , Santen Richard J.
Published: March 2023

Abstract
Secondary resistance to hormonal therapy for breast cancer commonly develops after an initial response to tamoxifen or aromatase inhibitors. Agents to abrogate these adaptive changes would substantially enhance the long-term benefits of hormonal therapy. Our studies with a stilbene derivative called TMS (2,3′,4,5′-tetramethoxystilbene) identified unexpected effects with potential utility for treatment of breast tumors secondarily resistant to hormonal therapy. TMS was originally developed as an inhibitor of cytochrome P450 1B1 to block the conversion of estradiol to 4-OH-estradiol. While studying this agent in three models of hormone resistance, we detected direct antitumor effects not related to its role as an inhibitor of catecholestrogens. During examination of the mechanisms involved, we showed that treatment with 3 μmol/L TMS for 24 h inhibited tubulin polymerization and microtubule formation, caused a cell cycle block at the G2-M phase, and induced apoptosis. TMS also inhibited activated focal adhesion kinase (FAK), Akt, and mammalian target of rapamycin (mTOR) and stimulated c-jun-NH2-kinase and p38 mitogen-activated protein kinase activity. With respect to antitumor effects, TMS at a concentrations of 0.2 to 0.3 μmol/L inhibited the growth of long-term tamoxifen-treated MCF-7 cells by 80% and fulvestrant-treated MCF-7 cells by 70%. In vivo studies, involving 8 weeks of treatment with TMS via a 30-mg s.c. implant, reduced tumor volume of tamoxifen-resistant MCF-7 breast cancer xenografts by 53%. Our data suggest that TMS is a promising therapeutic agent because of its unique ability to block several pathways involved in the development of hormone resistance. [Cancer Res 2007;67(12):5717–26]
Data from Amphipathic Peptide-Based Fusion Peptides and Immunoconjugates for the Targeted Ablation of Prostate Cancer Cells
Authors: Rege Kaushal , Patel Suraj J. , Megeed Zaki , Yarmush Martin L.
Published: March 2023

Abstract
We describe the design, generation, and in vitro evaluation of targeted amphipathic fusion peptides and immunoconjugates for the ablation of prostate cancer cells. The overexpression of the prostate-specific membrane antigen (PSMA) was exploited as means to specifically deliver cytotoxic peptides to prostate cancer cells. Cationic amphipathic lytic peptides were chosen as cytotoxic agents due to their ability to depolarize mitochondrial membranes and induce apoptosis. Specific delivery of the lytic peptide was facilitated by PSMA-targeting peptides and antibodies. Our results indicate that although the use of PSMA-targeted peptides only modestly enhanced the cytotoxic activity of the lytic peptide, peptide-antibody conjugates were two orders of magnitude more potent than untargeted peptide. In addition to quantifying the cytotoxic activities of the individual constructs, we also investigated the mechanisms of cell death induced by the fusion peptides and immunoconjugates. Although fusion peptides induced oncotic/necrotic death in cells, treatment with immunoconjugates resulted in apoptotic death. In summary, immunoconjugates based on lytic peptides are a promising class of therapeutics for prostate cancer therapy and warrant further investigation. [Cancer Res 2007;67(13):6368–75]
Data from Dominant-Negative but not Gain-of-Function Effects of a p53.R270H Mutation in Mouse Epithelium Tissue after DNA Damage
Authors: Wijnhoven Susan W.P. , Speksnijder Ewoud N. , Liu Xiaoling , Zwart Edwin , vanOostrom Conny Th. M. , Beems Rudolf B. , Hoogervorst Esther M. , Schaap Mirjam M. , Attardi Laura D. , Jacks Tyler , van Steeg Harry , Jonkers Jos , de Vries Annemieke
Published: March 2023

Abstract
p53 alterations in human tumors often involve missense mutations that may confer dominant-negative or gain-of-function properties. Dominant-negative effects result in inactivation of wild-type p53 protein in heterozygous mutant cells and as such in a p53 null phenotype. Gain-of-function effects can directly promote tumor development or metastasis through antiapoptotic mechanisms or transcriptional activation of (onco)genes. Here, we show, using conditional mouse technology, that epithelium-specific heterozygous expression of mutant p53 (i.e., the p53.R270H mutation that is equivalent to the human hotspot R273H) results in an increased incidence of spontaneous and UVB-induced skin tumors. Expression of p53.R270H exerted dominant-negative effects on latency, multiplicity, and progression status of UVB-induced but not spontaneous tumors. Surprisingly, gain-of-function properties of p53.R270H were not detected in skin epithelium. Apparently, dominant-negative and gain-of-function effects of mutant p53 are highly tissue specific and become most manifest upon stabilization of p53 after DNA damage. [Cancer Res 2007;67(10):4648–56]
Data from Quantitative Assessment of the p53-Mdm2 Feedback Loop Using Protein Lysate Microarrays
Authors: Ramalingam Sundhar , Honkanen Peter , Young Lynn , Shimura Tsutomu , Austin John , Steeg Patricia S. , Nishizuka Satoshi
Published: March 2023

Abstract
Mathematical simulations of the p53-Mdm2 feedback loop suggest that both proteins will exhibit impulsive expression characteristics in response to high cellular stress levels. However, little quantitative experimental evaluation has been done, particularly of the phosphorylated forms. To evaluate the mathematical models experimentally, we used lysate microarrays from an isogenic pair of γ-ray–irradiated cell lysates from HCT116 (p53+/+ and p53−/−). Both p53 and Mdm2 proteins showed expected pulses in the wild type, whereas no pulses were seen in the knockout. Based on experimental observations, we determined model parameters and generated an in silico “knockout,” reflecting the experimental data, including phosphorylated proteins. [Cancer Res 2007;67(13):6247–52]
Data from Protein Kinase Cα Determines HER2 Fate in Breast Carcinoma Cells with HER2 Protein Overexpression without Gene Amplification
Authors: Magnifico Alessandra , Albano Luisa , Campaner Stefano , Campiglio Manuela , Pilotti Silvana , Ménard Sylvie , Tagliabue Elda
Published: March 2023

Abstract
In some HER2-positive breast tumors, cell surface overexpression of HER2 is not associated with gene amplification but may instead rest in altered gene transcription, half-life, or recycling of the oncoprotein. Here, we show that HER2 overexpression in HER2 2+ carcinomas is associated with neither an increase in gene transcription nor a deregulation in the ubiquitin-dependent pathways, but instead seems to be regulated by protein kinase Cα (PKCα) activity. The stimulation of PKCα up-regulated HER2 expression, whereas PKCα inhibition by pharmacologic treatments and PKCα-specific small interfering RNA led to a dramatic down-regulation of HER2 levels only in breast cancer cells HER2 2+. Consistent with the in vitro data, our biochemical analysis of HER2 2+ human primary breast specimens revealed significantly higher levels of phosphorylated PKCα compared with HER2-negative tumors. Inhibition of HER2 activation by the tyrosine kinase inhibitor lapatinib led to decreased levels of PKCα phosphorylation, clearly indicating a cross-talk between PKCα and HER2 molecules. These data suggest that HER2 overexpression in HER2 2+ carcinomas is due to an accumulation of the recycled oncoprotein to the cell surface induced by activated PKCα. [Cancer Res 2007;67(11):5308–17]
Data from Tumor Suppressor Activity of CCAAT/Enhancer Binding Protein α Is Epigenetically Down-regulated in Head and Neck Squamous Cell Carcinoma
Authors: Bennett Kristi L. , Hackanson Björn , Smith Laura T. , Morrison Carl D. , Lang James C. , Schuller David E. , Weber Frank , Eng Charis , Plass Christoph
Published: March 2023

Abstract
Tumor suppressor CCAAT enhancer binding protein α (C/EBPα) is a transcription factor involved in cell cycle control and cellular differentiation. In a recent study, microarray expression profiling on head and neck squamous cell carcinoma (HNSCC) samples identified significant C/EBPα down-regulation, correlating with poor prognosis. However, the mechanisms of C/EBPα down-regulation remained elusive. C/EBPα has been previously found to provide an antiproliferative role in lung cancer, and our laboratory showed that its down-regulation involves epigenetic mechanisms. This prompted us to investigate the involvement of epigenetics in down-regulating C/EBPα in HNSCC. Here, we show that C/EBPα is down-regulated in HNSCC by loss of heterozygosity and DNA methylation, but not by gene mutation. We found a consistently methylated upstream regulatory region (−1,399 bp to −1,253 bp in relation to the transcription start site) in 68% of the HNSCC tumor samples, and DNA demethylation using 5-aza-2′-deoxycytidine treatment was able to significantly restore C/EBPα mRNA expression in the HNSCC cell lines we tested. In addition, C/EBPα overexpression in a HNSCC cell line (SCC22B) revealed its ability to provide tumor suppressor activity in HNSCC in vitro and in vivo. In conclusion, we showed for the first time not only that C/EBPα has tumor suppressor activity in HNSCC, but also that it is down-regulated by DNA promoter methylation. [Cancer Res 2007;67(10):4657–64]
Data from Dual Specificity Phosphatase 1/CL100 Is a Direct Transcriptional Target of E2F-1 in the Apoptotic Response to Oxidative Stress
Authors: Wang Jianli , Yin David P. , Liu Yu-Xin , Baer Richard , Yin Yuxin
Published: March 2023

Abstract
E2F-1 mediates apoptosis through transcriptional regulation of its targets. We report here that E2F-1 acts as a direct transcriptional regulator of dual specificity phosphatase 1 (DUSP1; CL100), a threonine and tyrosine phosphatase that inhibits mitogen-activated protein (MAP) kinases. We found that DUSP1 is transcriptionally induced by ectopic E2F-1 expression and that extracellular signal–regulated kinase 1/2 are dephosphorylated in the presence of E2F-1 and DUSP1. E2F-1 mediates apoptosis in the cellular response to oxidative stress. DUSP1 levels are significantly increased in an E2F-1–dependent manner following oxidative stress but not other stresses examined. DUSP1 mediates the cellular response to oxidative stress. We found that E2F-1 binds to chromatin encompassing the DUSP1 promoter and greatly stimulates the promoter activity of the DUSP1 gene. In particular, E2F-1 physically binds to an E2F-1 consensus sequence and a palindromic motif in the DUSP1 promoter. Interestingly, E2F-1 is acetylated following oxidative stress. Our findings show that E2F-1 is a transcriptional activator of DUSP1 and that DUSP1 is a link between E2F-1 and MAP kinases. [Cancer Res 2007;67(14):6737–44]
Data from Deletion of the AU-Rich RNA Binding Protein Apobec-1 Reduces Intestinal Tumor Burden in Apcmin Mice
Authors: Blanc Valerie , Henderson Jeffrey O. , Newberry Rodney D. , Xie Yan , Cho Soo-Jin , Newberry Elizabeth P. , Kennedy Susan , Rubin Deborah C. , Wang Hanlin L. , Luo Jianyang , Davidson Nicholas O.
Published: March 2023

Abstract
The RNA-specific cytidine deaminase apobec-1 is an AU-rich RNA binding protein that binds the 3′ untranslated region (UTR) of cyclooxygenase-2 (Cox-2) mRNA and stabilizes its turnover in vitro. Cox-2 overexpression accompanies intestinal adenoma formation in both humans and mice. Evidence from both genetic deletion studies as well as from pharmacologic inhibition has implicated Cox-2 in the development of intestinal adenomas in experimental animals and in adenomas and colorectal cancer in humans. Here, we show that small intestinal adenoma formation is dramatically reduced in compound Apcmin/+ apobec-1−/− mice when compared with the parental Apcmin/+ strain. This reduced tumor burden was found in association with increased small intestinal apoptosis and reduced proliferation in small intestinal crypt-villus units from compound Apcmin/+ apobec-1−/− mice. Intestinal adenomas from compound Apcmin/+ apobec-1−/− mice showed a <2-fold increase in Cox-2 mRNA abundance and reduced prostaglandin E2 content compared with adenomas from the parental Apcmin/+ strain. In addition, there was reduced expression in adenomas from compound Apcmin/+ apobec-1−/− mice of other mRNAs (including epidermal growth factor receptor, peroxisome proliferator–activated receptor δ, prostaglandin receptor EP4, and c-myc), each containing the apobec-1 consensus binding site within their 3′-UTR. Adenovirus-mediated apobec-1 introduction into HCA-7 (colorectal cancer) cells showed a dose-dependent increase in Cox-2 protein and stabilization of endogenous Cox-2 mRNA. These findings suggest that deletion of apobec-1, by modulating expression of AU-rich RNA targets, provides an important mechanism for attenuating a dominant genetic restriction point in intestinal adenoma formation. [Cancer Res 2007;67(18):8565–73]
Data from Characterization of Viral Particles Isolated from Primary Cultures of Human Breast Cancer Cells
Authors: Melana Stella M. , Nepomnaschy Irene , Sakalian Michael , Abbott Andrea , Hasa Jennifer , Holland James F. , Pogo Beatriz G.T.
Published: March 2023

Abstract
The association of human breast cancer with sequences similar to the mouse mammary tumor virus (MMTV) has been shown, but convincing evidence for the presence of viral particles in breast tumors has been lacking. We have described the complete proviral structure of a retrovirus in human breast cancer. This provirus, designated as human mammary tumor virus (HMTV), was 95% homologous to MMTV and revealed features of a replication-competent virus. We have therefore investigated the production of viral particles in primary cultures of human breast cancer (MSSM). Cells isolated from ascites or pleural effusions of patients with metastatic breast cancer contained viral sequences in their DNA, expressed Env protein, and showed retroviral particles by electron microscopy. Viral particles from culture media exhibited morphologic features of β-retroviruses sedimenting at buoyant densities of 1.12 to 1.18 g/mL in sucrose gradients and showed reverse transcriptase activity. cDNA sequences from virion RNA were synthesized, amplified, and sequenced and all the virion genes were detected and 70% of the virion RNA was sequenced. The sequence homologies were, respectively, 85% to 95% compared with the MMTV and HMTV proviruses we have previously described. These results clearly show that breast cancer cells in primary cultures produced HMTV viral particles that are similar to the mouse virus and which may play a role in human breast cancer pathogenesis. [Cancer Res 2007;67(18):8960–5]
Data from Tcl1 Expression in Chronic Lymphocytic Leukemia Is Regulated by miR-29 and miR-181
Authors: Pekarsky Yuri , Santanam Urmila , Cimmino Amelia , Palamarchuk Alexey , Efanov Alexey , Maximov Vadim , Volinia Stefano , Alder Hansjuerg , Liu Chang-Gong , Rassenti Laura , Calin George A. , Hagan John P. , Kipps Thomas , Croce Carlo M.
Published: March 2023

Abstract
B-cell chronic lymphocytic leukemia (B-CLL) is the most common human leukemia in the world. Deregulation of the TCL1 oncogene is a causal event in the pathogenesis of the aggressive form of this disease as was verified by using animal models. To study the mechanism of Tcl1 regulation in CLL, we carried out microRNA expression profiling of three types of CLL: indolent CLL, aggressive CLL, and aggressive CLL showing 11q deletion. We identified distinct microRNA signatures corresponding to each group of CLL. We further determined that Tcl1 expression is regulated by miR-29 and miR-181, two microRNAs differentially expressed in CLL. Expression levels of miR-29 and miR-181 generally inversely correlated with Tcl1 expression in the CLL samples we examined. Our results suggest that Tcl1 expression in CLL is, at least in part, regulated by miR-29 and miR-181 and that these microRNAs may be candidates for therapeutic agents in CLLs overexpressing Tcl1. (Cancer Res 2006; 66(24): 11590-3)
Data from Epigenetic Inactivation of a Cluster of Genes Flanking MLH1 in Microsatellite-Unstable Colorectal Cancer
Authors: Hitchins Megan P. , Lin Vita Ap , Buckle Andrew , Cheong Kayfong , Halani Nimita , Ku Su , Kwok Chau-To , Packham Deborah , Suter Catherine M. , Meagher Alan , Stirzaker Clare , Clark Susan , Hawkins Nicholas J. , Ward Robyn L.
Published: March 2023

Abstract
Biallelic promoter methylation and transcriptional silencing of the MLH1 gene occurs in the majority of sporadic colorectal cancers exhibiting microsatellite instability due to defective DNA mismatch repair. Long-range epigenetic silencing of contiguous genes has been found on chromosome 2q14 in colorectal cancer. We hypothesized that epigenetic silencing of MLH1 could occur on a regional scale affecting additional genes within 3p22, rather than as a focal event. We studied the levels of CpG island methylation and expression of multiple contiguous genes across a 4 Mb segment of 3p22 including MLH1 in microsatellite-unstable and -stable cancers, and their paired normal colonic mucosa. We found concordant CpG island hypermethylation, H3-K9 dimethylation and transcriptional silencing of MLH1 and multiple flanking genes spanning up to 2.4 Mb in microsatellite-unstable colorectal cancers. This region was interspersed with unmethylated genes, which were also transcriptionally repressed. Expression of both methylated and unmethylated genes was reactivated by methyltransferase and histone deacetylase inhibitors in a microsatellite-unstable colorectal carcinoma cell line. Two genes at the telomeric end of the region were also hypermethylated in microsatellite-stable cancers, adenomas, and at low levels in normal colonic mucosa from older individuals. Thus, the cluster of genes flanking MLH1 that was specifically methylated in the microsatellite-unstable group of cancers extended across 1.1 Mb. Our results show that coordinate epigenetic silencing extends across a large chromosomal region encompassing MLH1 in microsatellite-unstable colorectal cancers. Simultaneous epigenetic silencing of this cluster of 3p22 genes may contribute to the development or progression of this type of cancer. [Cancer Res 2007;67(19):9107–16]
Data from Novel Pheochromocytoma Susceptibility Loci Identified by Integrative Genomics
Authors: Dahia Patricia L.M. , Hao Ke , Rogus John , Colin Christian , Pujana Miguel A.G. , Ross Ken , Magoffin Danielle , Aronin Neil , Cascon Alberto , Hayashida César Y. , Li Cheng , Toledo Sérgio P.A. , Stiles Charles D.
Published: March 2023

Abstract
Pheochromocytomas are catecholamine-secreting tumors that result from mutations of at least six different genes as components of distinct autosomal dominant disorders. However, there remain familial occurrences of pheochromocytoma without a known genetic defect. We describe here a familial pheochromocytoma syndrome consistent with digenic inheritance identified through a combination of global genomics strategies. Multipoint parametric linkage analysis revealed identical LOD scores of 2.97 for chromosome 2cen and 16p13 loci. A two-locus parametric linkage analysis produced maximum LOD score of 5.16 under a double recessive multiplicative model, suggesting that both loci are required to develop the disease. Allele-specific loss of heterozygosity (LOH) was detected only at the chromosome 2 locus in all tumors from this family, consistent with a tumor suppressor gene. Four additional pheochromocytomas with a similar genetic pattern were identified through transcription profiling and helped refine the chromosome 2 locus. High-density LOH mapping with single nucleotide polymorphism–based array identified a total of 18 of 62 pheochromocytomas with LOH within the chromosome 2 region, which further narrowed down the locus to <2 cM. This finding provides evidence for two novel susceptibility loci for pheochromocytoma and adds a recessive digenic trait to the increasingly broad genetic heterogeneity of these tumors. Similarly, complex traits may also be involved in other familial cancer syndromes.
Data from Identification of an Integrated SV40 T/t-Antigen Cancer Signature in Aggressive Human Breast, Prostate, and Lung Carcinomas with Poor Prognosis
Authors: Deeb Kristin K. , Michalowska Aleksandra M. , Yoon Cheol-yong , Krummey Scott M. , Hoenerhoff Mark J. , Kavanaugh Claudine , Li Ming-chung , Demayo Francesco J. , Linnoila Ilona , Deng Chu-xia , Lee Eva Y-H.P. , Medina Daniel , Shih Joanna H. , Green Jeffrey E.
Published: March 2023

Abstract
Understanding the genetic architecture of cancer pathways that distinguishes subsets of human cancer is critical to developing new therapies that better target tumors based on their molecular expression profiles. In this study, we identify an integrated gene signature from multiple transgenic models of epithelial cancers intrinsic to the functions of the Simian virus 40 T/t-antigens that is associated with the biological behavior and prognosis for several human epithelial tumors. This genetic signature, composed primarily of genes regulating cell replication, proliferation, DNA repair, and apoptosis, is not a general cancer signature. Rather, it is uniquely activated primarily in tumors with aberrant p53, Rb, or BRCA1 expression but not in tumors initiated through the overexpression of myc, ras, her2/neu, or polyoma middle T oncogenes. Importantly, human breast, lung, and prostate tumors expressing this set of genes represent subsets of tumors with the most aggressive phenotype and with poor prognosis. The T/t-antigen signature is highly predictive of human breast cancer prognosis. Because this class of epithelial tumors is generally intractable to currently existing standard therapies, this genetic signature identifies potential targets for novel therapies directed against these lethal forms of cancer. Because these genetic targets have been discovered using mammary, prostate, and lung T/t-antigen mouse cancer models, these models are rationale candidates for use in preclinical testing of therapies focused on these biologically important targets. [Cancer Res 2007;67(17):8065–80]
Data from ERM/ETV5 Up-regulation Plays a Role during Myometrial Infiltration through Matrix Metalloproteinase-2 Activation in Endometrial Cancer
Authors: Monge Marta , Colas Eva , Doll Andreas , Gonzalez Marta , Gil-Moreno Antonio , Planaguma Jesus , Quiles Maite , Arbos Maria Antonia , Garcia Angel , Castellvi Josep , Llaurado Marta , Rigau Marina , Alazzouzi Hafid , Xercavins Jordi , Alameda Francesc , Reventos Jaume , Abal Miguel
Published: March 2023

Abstract
We have described recently the Ets family transcription factor, ERM/ETV5, specifically up-regulated in endometrioid endometrial carcinoma (EEC) and associated with myometrial infiltration. Ets family members have been correlated to tumor progression by up-regulating the expression of matrix-degrading proteases. In the present study, we investigated the possibility that in EEC, ERM/ETV5 may act by inducing the expression of genes involved in extracellular matrix remodeling. Unraveling the molecular events associated with the initiation of tumor invasion would represent an obvious improvement for EEC patients. The overexpression of ERM/ETV5 induced scattering in the endometrial cancer cell line Hec-1A, correlating to increased matrix metalloproteinase-2 (MMP-2) gelatinase activity. Both chromatin immunoprecipitation and reversion experiments with RNA interference and specific MMP-2 inhibitor showed a functional link between ERM/ETV5 overexpression and MMP-2 activation. The increased MMP-2 activity associated with overexpressed ERM/ETV5 in a mouse model conferred invasive capacity to endometrial tumors. Orthotopically implanted overexpressing ERM/ETV5 tumors presented a more aggressive and infiltrative pattern of myometrial invasion. Finally, the specific localization of ERM/ETV5 and MMP-2 at the invasive front of myometrial infiltrating human endometrial carcinomas further reinforced the hypothesis of a role for ERM/ETV5 in the early steps of endometrial dissemination. Taken together, these results lead us to propose that in EEC, ERM/ETV5 acts through MMP-2 gelatinolytic activity to confer invasive capabilities, associated with an initial switch to myometrial infiltration. They also postulate ERM/ETV5 as a valuable marker for patient stratification and a transcription pathway that should be evaluated for therapies specifically targeting the initial steps of EEC dissemination. [Cancer Res 2007;67(14):6753–9]
Data from Cyclin G1 Is a Target of miR-122a, a MicroRNA Frequently Down-regulated in Human Hepatocellular Carcinoma
Authors: Gramantieri Laura , Ferracin Manuela , Fornari Francesca , Veronese Angelo , Sabbioni Silvia , Liu Chang-Gong , Calin George A. , Giovannini Catia , Ferrazzi Eros , Grazi Gian Luca , Croce Carlo M. , Bolondi Luigi , Negrini Massimo
Published: March 2023

Abstract
We investigated the role of microRNAs (miRNAs) in the pathogenesis of human hepatocellular carcinoma (HCC). A genome-wide miRNA microarray was used to identify differentially expressed miRNAs in HCCs arisen on cirrhotic livers. Thirty-five miRNAs were identified. Several of these miRNAs were previously found deregulated in other human cancers, such as members of the let-7 family, mir-221, and mir-145. In addition, the hepato-specific miR-122a was found down-regulated in ∼70% of HCCs and in all HCC-derived cell lines. Microarray data for let-7a, mir-221, and mir-122a were validated by Northern blot and real-time PCR analysis. Understanding the contribution of deregulated miRNAs to cancer requires the identification of gene targets. Here, we show that miR-122a can modulate cyclin G1 expression in HCC-derived cell lines and an inverse correlation between miR-122a and cyclin G1 expression exists in primary liver carcinomas. These results indicate that cyclin G1 is a target of miR-122a and expand our knowledge of the molecular alterations involved in HCC pathogenesis and of the role of miRNAs in human cancer. [Cancer Res 2007;67(13):6092–9]
Data from Lung Cancer Cell Lines Harboring MET Gene Amplification Are Dependent on Met for Growth and Survival
Authors: Lutterbach Bart , Zeng Qinwen , Davis Lenora J. , Hatch Harold , Hang Gaozhen , Kohl Nancy E. , Gibbs Jackson B. , Pan Bo-Sheng
Published: March 2023

Abstract
Recent clinical successes of small-molecule epidermal growth factor receptor (EGFR) inhibitors in treating advanced non–small cell lung cancer (NSCLC) have raised hopes that the identification of other deregulated growth factor pathways in NSCLC will lead to new therapeutic options for NSCLC. Met, the receptor for hepatocyte growth factor, has been implicated in growth, invasion, and metastasis of many tumors including NSCLC. To assess the functional role for Met in NSCLC, we evaluated a panel of nine lung cancer cell lines for Met gene amplification, Met expression, Met pathway activation, and the sensitivity of the cell lines to short hairpin RNA (shRNA)–mediated Met knockdown. Two cell lines, EBC-1 and H1993, showed significant Met gene amplification and overexpressed Met receptors which were constitutively phosphorylated. The other seven lines did not exhibit Met amplification and expressed much lower levels of Met, which was phosphorylated only on addition of hepatocyte growth factor. We also found a strong up-regulation of tyrosine phosphorylation in β-catenin and p120/δ-catenin in the Met-amplified EBC-1 and H1993 cell lines. ShRNA-mediated Met knockdown induced significant growth inhibition, G1-S arrest, and apoptosis in EBC-1 and H1993 cells, whereas it had little or no effect on the cell lines that do not have Met amplification. These results strongly suggest that Met amplification identifies a subset of NSCLC likely to respond to new molecular therapies targeting Met. [Cancer Res 2007;67(5):2081–8]
Data from The Tumor Suppressor Gene hCDC4 Is Frequently Mutated in Human T-Cell Acute Lymphoblastic Leukemia with Functional Consequences for Notch Signaling
Authors: Malyukova Alena , Dohda Takeaki , von der Lehr Natalie , Akhondi Shahab , Corcoran Martin , Heyman Mats , Spruck Charles , Grandér Dan , Lendahl Urban , Sangfelt Olle
Published: March 2023

Abstract
Notch signaling is of crucial importance in normal T-cell development and Notch 1 is frequently mutated in T-cell acute lymphoblastic leukemias (T-ALL), leading to aberrantly high Notch signaling. In this report, we determine whether T-ALL mutations occur not only in Notch1 but also in the F-box protein hCdc4 (Sel-10, Ago, or Fbxw7), a negative regulator of Notch1. We show that the hCDC4 gene is mutated in leukemic cells from more than 30% of patients with pediatric T-ALL and derived cell lines. Most hCDC4 mutations found were missense substitutions at critical arginine residues (Arg465, Arg479, and Arg505) localized in the substrate-binding region of hCdc4. Cells inactivated for hCdc4 and T-ALL cells containing hCDC4 mutations exhibited an increased Notch1 protein half-life, consistent with the proposed role of hCdc4 in ubiquitin-dependent proteolysis of Notch1. Furthermore, restoration of wild-type but not mutant hCdc4 in HCT 116 hCDC4-negative cells led to an increased Notch1 ubiquitylation and decreased Notch1 signaling. These results show that hCdc4 mutations interfere with normal Notch1 regulation in vivo. Finally, we found that mutations in hCDC4 and NOTCH1 can occur in the same cancers and that patients carrying hCDC4 and/or NOTCH1 mutations have a favorable overall survival. Collectively, these data show that mutation of hCDC4 is a frequent event in T-ALL and suggest that hCDC4 mutations and gain-of-function mutations in NOTCH1 might synergize in contributing to the development of pediatric T-ALL leukemogenesis. [Cancer Res 2007;67(12):5611–6]
Data from Docosahexaenoic Acid and Butyrate Synergistically Induce Colonocyte Apoptosis by Enhancing Mitochondrial Ca2+ Accumulation
Authors: Kolar Satya Sree N. , Barhoumi Rola , Lupton Joanne R. , Chapkin Robert S.
Published: March 2023

Abstract
We have previously shown that butyrate, a short-chain fatty acid fiber fermentation product, induces colonocyte apoptosis via a nonmitochondrial, Fas-mediated, extrinsic pathway. Interestingly, fermentable fiber when combined with fish oil containing docosahexaenoic acid (DHA, 22:6n-3) exhibits an enhanced ability to induce apoptosis and protect against colon tumorigenesis. To determine the molecular mechanism of action, the effect of DHA and butyrate cotreatment on intracellular Ca2+ homeostasis was examined. Mouse colonocytes were treated with 50 μmol/L DHA or linoleic acid (LA) for 72 h ± butyrate (0–10 mmol/L) for the final 24 h. Cytosolic and mitochondrial Ca2+ levels were measured using Fluo-4 and Rhod-2. DHA did not alter basal Ca2+ or the intracellular inositol trisphosphate (IP3) pool after 6 h butyrate cotreatment. In contrast, at 12 and 24 h, DHA- and butyrate-treated cultures exhibited a 25% and 38% decrease in cytosolic Ca2+ compared with LA and butyrate. Chelation of extracellular Ca2+ abolished the effect of thapsigargin on the IP3-releasable Ca2+ pool. DHA and butyrate cotreatment compared with untreated cells increased the mitochondrial-to-cytosolic Ca2+ ratio at 6, 12, and 24 h by 73%, 18%, and 37%, respectively. The accumulation of mitochondrial Ca2+ preceded the onset of apoptosis. RU-360, a mitochondrial-uniporter inhibitor, abrogated mitochondrial Ca2+ accumulation and also partially blocked apoptosis in DHA and butyrate cotreated cells. Collectively, these data show that the combination of DHA and butyrate, compared with butyrate alone, further enhances apoptosis by additionally recruiting a Ca2+-mediated intrinsic mitochondrial pathway. [Cancer Res 2007;67(11):5561–8]
Data from The High-Mobility Group A1 Gene Up-Regulates Cyclooxygenase 2 Expression in Uterine Tumorigenesis
Authors: Tesfaye Abeba , Di Cello Francescopaolo , Hillion Joelle , Ronnett Brigitte M. , Elbahloul Ossama , Ashfaq Raheela , Dhara Surajit , Prochownik Edward , Tworkoski Kathryn , Reeves Raymond , Roden Richard , Ellenson Lora Hedrick , Huso David L. , Resar Linda M. S.
Published: March 2023

Abstract
Uterine cancer is the most common cancer of the female genital tract and is the fourth most frequent cause of cancer death in women in the U.S. Despite the high prevalence of uterine cancers, the molecular events that lead to neoplastic transformation in the uterus are poorly understood. Moreover, there are limited mouse models to study these malignancies. We generated transgenic mice with high-mobility group A1 gene (HMGA1a) expression targeted to uterine tissue and all female mice developed tumors by 9 months of age. Histopathologically, the tumors resemble human uterine adenosarcoma and are transplantable. To determine whether these findings are relevant to human disease, we evaluated primary human uterine neoplasms and found that HMGA1a mRNA and protein levels are increased in most high-grade neoplasms but not in normal uterine tissue, benign tumors, or most low-grade neoplasms. We also found that HMGA1a up-regulates cyclooxygenase 2 (COX-2) expression in transgenic tumors. Moreover, both HMGA1a and COX-2 expression are up-regulated in high-grade human leiomyosarcomas. Using chromatin immunoprecipitation, HMGA1a binds directly to the COX-2 promoter in human uterine cancer cells in vivo and activates its expression in transfection experiments. We also show that blocking either HMGA1a or COX-2 in high-grade human uterine cancer cells blocks anchorage-independent cell growth in methylcellulose. These findings show that HMGA1a functions as an oncogene when overexpressed in the uterus and contributes to the pathogenesis of human uterine cancer by activating COX-2 expression. Although a larger study is needed to confirm these results, HMGA1a may be a useful marker for aggressive human uterine cancers. [Cancer Res 2007;67(9):3998–4004]