bluuebunny/crossref_metadata_2025 huggingface dataset:
Data from Enhanced Activation of Epidermal Growth Factor Receptor Caused by Tumor-Derived E-Cadherin Mutations
Authors: Bremm Anja , Walch Axel , Fuchs Margit , Mages Jörg , Duyster Justus , Keller Gisela , Hermannstädter Christine , Becker Karl-Friedrich , Rauser Sandra , Langer Rupert , von Weyhern Claus Hann , Höfler Heinz , Luber Birgit
Published: March 2024

Abstract
Mutations of the tumor suppressor E-cadherin and overexpression of the receptor tyrosine kinase epidermal growth factor receptor (EGFR) are among the most frequent genetic alterations associated with diffuse-type gastric carcinoma. Accumulating evidence suggests a functional relationship between E-cadherin and EGFR that regulates both proteins. We report that somatic mutation of E-cadherin is associated with increased activation of EGFR followed by enhanced recruitment of the downstream acting signaling components growth factor receptor binding protein 2 and Shc, and activation of Ras. Reduced complex formation of mutant E-cadherin — with an in frame deletion of exon 8 in the extracellular domain resulting in reduced adhesion and increased motility — with EGFR was observed compared with wild-type E-cadherin. We conclude that reduced binding of mutant E-cadherin to EGFR in a multicomponent complex or reduced stability of the complex may enhance EGFR surface motility, thereby facilitating EGFR dimerization and activation. Furthermore, reduced surface localization due to enhanced internalization of mutant E-cadherin compared with the wild-type protein was observed. The internalization of EGFR was decreased in response to epidermal growth factor stimulation in cells expressing mutant E-cadherin, suggesting that mutation of E-cadherin also influences the endocytosis of EGFR. Moreover, we show increased activation of EGFR in gastric carcinoma samples with mutant E-cadherin lacking exons 8 or 9. In summary, we describe activation of EGFR by mutant E-cadherin as a novel mechanism in tumor cells that explains the enhanced motility of tumor cells in the presence of an extracellular mutation of E-cadherin. [Cancer Res 2008;68(3):707–14]
Data from Epithelial-Mesenchymal Transition in Breast Cancer Relates to the Basal-like Phenotype
Authors: Sarrió David , Rodriguez-Pinilla Socorro María , Hardisson David , Cano Amparo , Moreno-Bueno Gema , Palacios José
Published: March 2024

Abstract
Epithelial-mesenchymal transition (EMT) is defined by the loss of epithelial characteristics and the acquisition of a mesenchymal phenotype. In carcinoma cells, EMT can be associated with increased aggressiveness, and invasive and metastatic potential. To assess the occurrence of EMT in human breast tumors, we conducted a tissue microarray–based immunohistochemical study in 479 invasive breast carcinomas and 12 carcinosarcomas using 28 different markers. Unsupervised hierarchical clustering of the tumors and statistical analysis showed that up-regulation of EMT markers (vimentin, smooth-muscle-actin, N-cadherin, and cadherin-11) and overexpression of proteins involved in extracellular matrix remodeling and invasion (SPARC, laminin, and fascin), together with reduction of characteristic epithelial markers (E-cadherin and cytokeratins), preferentially occur in breast tumors with the “basal-like phenotype.” Moreover, most breast carcinosarcomas also had a basal-like phenotype and showed expression of mesenchymal markers in their sarcomatous and epithelial components. To assess whether basal-like cells have intrinsic phenotypic plasticity for mesenchymal transition, we performed in vitro studies with the MCF10A cell line. In response to low cell density, MCF10A cells suffer spontaneous morphologic and phenotypic EMT-like changes, including cytoskeleton reorganization, vimentin and Slug up-regulation, cadherin switching, and diffuse cytosolic relocalization of the catenins. Moreover, these phenotypic changes are associated with modifications in the global genetic differentiation program characteristic of the EMT process. In summary, our data indicate that in breast tumors, EMT likely occurs within a specific genetic context, the basal phenotype, and suggests that this proclivity to mesenchymal transition may be related to the high aggressiveness and the characteristic metastatic spread of these tumors. [Cancer Res 2008;68(4):989–97]
Data from Clonal Selection in Malignant Transformation of Human Fibroblasts Transduced with Defined Cellular Oncogenes
Authors: Mahale Alka M. , Khan Zahid A.T. , Igarashi Makoto , Nanjangud Gouri J. , Qiao Rui Fang , Yao Shen , Lee Sam W. , Aaronson Stuart A.
Published: March 2024

Abstract
Recent evidence has implied that disruption of a limited number of defined cellular pathways is necessary and sufficient for neoplastic conversion of a variety of normal human cell types in tissue culture. We show instead that malignancy in such models results from an iterative process of clonal selection in vitro and/or in vivo. Normal human fibroblasts underwent malignant transformation after transduction with telomerase, cyclin-dependent kinase 4, dominant-negative p53, and activated Ras or MEK. Furthermore, culture conditions favoring overgrowth resulted in clonal selection, which with added Ras or MEK oncogenes led to the emergence of tumorigenic clones. Such tumors showed variable degrees of malignancy with some even exhibiting metastasis. SV40 small t antigen (ST) has been reported to be necessary and sufficient to convert human fibroblasts with these pathway aberrations to a polyclonal tumor. However, we observed that clonal tumors emerged even with ST addition. Genomic instability was markedly increased by p53 and Rb pathway abrogation. Under the same conditions, fibroblasts with these alterations failed to induce tumors, implying that genomic instability may be necessary but not sufficient for malignant transformation. These findings indicate that the minimum number of events required for malignant transformation of human fibroblasts is greater than has been enumerated by such oncogene addition strategies and support a stochastic cancer progression model initiated by four defined cellular alterations. [Cancer Res 2008;68(5):1417–26]
Data from Cancer Stem Cells Contribute to Cisplatin Resistance in Brca1/p53–Mediated Mouse Mammary Tumors
Authors: Shafee Norazizah , Smith Christopher R. , Wei Shuanzeng , Kim Yoon , Mills Gordon B. , Hortobagyi Gabriel N. , Stanbridge Eric J. , Lee Eva Y-H. P.
Published: March 2024

Abstract
The majority of BRCA1-associated breast cancers are basal cell–like, which is associated with a poor outcome. Using a spontaneous mouse mammary tumor model, we show that platinum compounds, which generate DNA breaks during the repair process, are more effective than doxorubicin in Brca1/p53–mutated tumors. At 0.5 mg/kg of daily cisplatin treatment, 80% primary tumors (n = 8) show complete pathologic response. At greater dosages, 100% show complete response (n = 19). However, after 2 to 3 months of complete remission following platinum treatment, tumors relapse and become refractory to successive rounds of treatment. Approximately 3.8% to 8.0% (mean, 5.9%) of tumor cells express the normal mammary stem cell markers, CD29hi24med, and these cells are tumorigenic, whereas CD29med24−/lo and CD29med24hi cells have diminished tumorigenicity or are nontumorigenic, respectively. In partially platinum-responsive primary transplants, 6.6% to 11.0% (mean, 8.8%) tumor cells are CD29hi24med; these populations significantly increase to 16.5% to 29.2% (mean, 22.8%; P < 0.05) in platinum-refractory secondary tumor transplants. Further, refractory tumor cells have greater colony-forming ability than the primary transplant–derived cells in the presence of cisplatin. Expression of a normal stem cell marker, Nanog, is decreased in the CD29hi24med populations in the secondary transplants. Top2A expression is also down-regulated in secondary drug-resistant tumor populations and, in one case, was accompanied by genomic deletion of Top2A. These studies identify distinct cancer cell populations for therapeutic targeting in breast cancer and implicate clonal evolution and expansion of cancer stem-like cells as a potential cause of chemoresistance. [Cancer Res 2008;68(9):3243–50]
Data from Inhibition of Endoplasmic Reticulum Stress–Induced Apoptosis of Melanoma Cells by the ARC Protein
Authors: Chen Li Hua , Jiang Chen Chen , Watts Ralph , Thorne Rick F. , Kiejda Kelly A. , Zhang Xu Dong , Hersey Peter
Published: March 2024

Abstract
We have shown previously that most melanoma cell lines are insensitive to endoplasmic reticulum (ER) stress–induced apoptosis, but resistance can be reversed through activation of caspase-4 by inhibition of the MEK/ERK pathway. We report in this study that apoptosis was induced by the ER stress inducer thapsigargin or tunicamycin via a caspase-8–mediated pathway in the melanoma cell line Me1007, although the MEK/ERK pathway was activated in this cell line. The high sensitivity of Me1007 to ER stress–induced apoptosis was associated with low expression levels of the apoptosis repressor with caspase recruitment domain (ARC) protein that was expressed at relatively high levels in the resistant melanoma cell lines. Transfection of cDNA encoding ARC into Me1007 cells inhibited both caspase-8 activation and apoptosis induced by thapsigargin or tunicamycin. In contrast, inhibition of ARC by small interfering RNA knockdown sensitized the resistant melanoma cell lines to ER stress–induced apoptosis, which was inhibitable by blockage of caspase-8 activation. Both exogenous and endogenous ARC seemed to predominantly locate to the cytoplasm and mitochondria and could be coimmunoprecipitated with caspase-8. Taken together, ER stress can potentially activate multiple apoptosis signaling pathways in melanoma cells in a context-dependent manner. Whereas the MEK/ERK signaling pathway plays an important role in inhibiting ER stress–induced caspase-4 activation, ARC seems to be critical in blocking activation of casapse-8 in melanoma cells subjected to ER stress. [Cancer Res 2008;68(3):834–42]
Data from Validation of the p21-Activated Kinases as Targets for Inhibition in Neurofibromatosis Type 2
Authors: Yi Chunling , Wilker Erik W. , Yaffe Michael B. , Stemmer-Rachamimov Anat , Kissil Joseph L.
Published: March 2024

Abstract
Neurofibromatosis type 2 (NF2) is a dominantly inherited cancer disorder caused by mutations at the NF2 gene locus. Merlin, the protein product of the NF2 gene, has been shown to negatively regulate Rac1 signaling by inhibiting its downstream effector kinases, the p21-activated kinases (Pak). Given the implication of Paks in tumorigenesis, it is plausible that merlin's tumor suppressive function might be mediated, at least in part, via inhibition of the Paks. We present data indicating this is indeed the case. First, analysis of primary schwannoma samples derived from NF2 patients showed that in a significant fraction of the tumors, the activity of Pak1 was highly elevated. Second, we used shRNAs to knockdown Pak1, 2, and 3 in NIH3T3 cells expressing a dominant-negative form of merlin, NF2BBA (NIH3T3/NF2BBA), and find that simultaneous knockdown of Pak1-3 in these cells significantly reduced their growth rates in vitro and inhibited their ability to form tumors in vivo. Finally, while attempting to silence Pak1 in rat schwannoma cells, we found that these cells were unable to tolerate long-term Pak1 inhibition and rapidly moved to restore Pak1 levels by shutting down Pak1 shRNA expression through a methylation-dependent mechanism. These data suggest that inhibiting Pak could be a beneficial approach for the development of therapeutics toward NF2. In addition, the finding that the shRNA-mediated Pak1 suppression was silenced rapidly by methylation raises questions about the future application of such technologies for the treatment of diseases such as cancer. [Cancer Res 2008;68(19):7932–7]
Data from Mouse Mesenchymal Stem Cells Expressing PAX-FKHR Form Alveolar Rhabdomyosarcomas by Cooperating with Secondary Mutations
Authors: Ren Yue-Xin , Finckenstein Friedrich Graf , Abdueva Diana A. , Shahbazian Violette , Chung Brile , Weinberg Kenneth I. , Triche Timothy J. , Shimada Hiroyuki , Anderson Michael J.
Published: March 2024

Abstract
Alveolar rhabdomyosarcomas (ARMS) are highly malignant soft-tissue sarcomas that arise in children, adolescents, and young adults. Although formation and expression of the PAX-FKHR fusion genes is thought to be the initiating event in this cancer, the role of PAX-FKHR in the neoplastic process remains largely unknown in a progenitor cell that is undefined. We hypothesize that PAX-FKHR determine the ARMS progenitor to the skeletal muscle lineage, which when coupled to the inactivation and/or activation of critical cell signaling pathways leads to the formation of ARMS. Because a number of studies have proposed that mesenchymal stem cells (MSC) are the progenitor for several of the sarcomas, we tested this hypothesis in MSCs. We show that PAX-FKHR induce skeletal myogenesis in MSCs by transactivating MyoD and myogenin. Despite exhibiting enhanced growth in vitro, the PAX-FKHR–expressing populations do not form colonies in soft agar or tumors in mice. Expression of dominant-negative p53, or the SV40 early region, elicits tumor formation in some of the PAX-FKHR–expressing populations. Additional activation of the Ras signaling pathway leads to highly malignant tumor formation for all of the populations. The PAX-FKHR–expressing tumors were shown to have histologic, immunohistochemical, and gene expression profiles similar to human ARMS. Our results show the critical role played by PAX-FKHR in determining the molecular, myogenic, and histologic phenotype of ARMS. More importantly, we identify MSCs as a progenitor that can give rise to ARMS. [Cancer Res 2008;68(16):6587–97]
Data from Genome-Wide Promoter Analysis Uncovers Portions of the Cancer Methylome
Authors: Hoque Mohammad Obaidul , Kim Myoung Sook , Ostrow Kimberly Laskie , Liu Junwei , Wisman G. Bea A. , Park Hannah Lui , Poeta Maria Luana , Jeronimo Carmen , Henrique Rui , Lendvai Ágnes , Schuuring Ed , Begum Shahnaz , Rosenbaum Eli , Ongenaert Maté , Yamashita Keishi , Califano Joseph , Westra William , van der Zee Ate G.J. , Criekinge Wim Van , Sidransky David
Published: March 2024

Abstract
DNA methylation has a role in mediating epigenetic silencing of CpG island genes in cancer and other diseases. Identification of all gene promoters methylated in cancer cells “the cancer methylome” would greatly advance our understanding of gene regulatory networks in tumorigenesis. We previously described a new method of identifying methylated tumor suppressor genes based on pharmacologic unmasking of the promoter region and detection of re-expression on microarray analysis. In this study, we modified and greatly improved the selection of candidates based on new promoter structure algorithm and microarray data generated from 20 cancer cell lines of 5 major cancer types. We identified a set of 200 candidate genes that cluster throughout the genome of which 25 were previously reported as harboring cancer-specific promoter methylation. The remaining 175 genes were tested for promoter methylation by bisulfite sequencing or methylation-specific PCR (MSP). Eighty-two of 175 (47%) genes were found to be methylated in cell lines, and 53 of these 82 genes (65%) were methylated in primary tumor tissues. From these 53 genes, cancer-specific methylation was identified in 28 genes (28 of 53; 53%). Furthermore, we tested 8 of the 28 newly identified cancer-specific methylated genes with quantitative MSP in a panel of 300 primary tumors representing 13 types of cancer. We found cancer-specific methylation of at least one gene with high frequency in all cancer types. Identification of a large number of genes with cancer-specific methylation provides new targets for diagnostic and therapeutic intervention, and opens fertile avenues for basic research in tumor biology. [Cancer Res 2008;68(8):2661–70]
Data from Targeting XIAP Bypasses Bcl-2–Mediated Resistance to TRAIL and Cooperates with TRAIL to Suppress Pancreatic Cancer Growth In vitro and In vivo
Authors: Vogler Meike , Walczak Henning , Stadel Dominic , Haas Tobias L. , Genze Felicitas , Jovanovic Marjana , Gschwend Jürgen E. , Simmet Thomas , Debatin Klaus-Michael , Fulda Simone
Published: March 2024

Abstract
Resistance to apoptosis is a hallmark of pancreatic cancer, a leading cause of cancer deaths. Therefore, novel strategies are required to target apoptosis resistance. Here, we report that the combination of X-linked inhibitor of apoptosis (XIAP) inhibition and tumor necrosis factor–related apoptosis-inducing ligand (TRAIL) is an effective approach to trigger apoptosis despite Bcl-2 overexpression and to suppress pancreatic cancer growth in vitro and in vivo. Knockdown of XIAP by RNA interference cooperates with TRAIL to induce caspase activation, loss of mitochondrial membrane potential, cytochrome c release, and apoptosis in pancreatic carcinoma cells. Loss of mitochondrial membrane potential and cytochrome c release are extensively inhibited by a broad range or caspase-3 selective caspase inhibitor and by RNAi-mediated silencing of caspase-3, indicating that XIAP inhibition enhances TRAIL-induced mitochondrial damage in a caspase-3–dependent manner. XIAP inhibition combined with TRAIL even breaks Bcl-2–imposed resistance by converting type II cells that depend on the mitochondrial contribution to the death receptor pathway to type I cells in which TRAIL-induced activation of caspase-3 and caspase-9 and apoptosis proceeds irrespective of high Bcl-2 levels. Most importantly, XIAP inhibition potentiates TRAIL-induced antitumor activity in two preclinical models of pancreatic cancer in vivo. In the chicken chorioallantoic membrane model, XIAP inhibition significantly enhances TRAIL-mediated apoptosis and suppression of tumor growth. In a tumor regression model in xenograft-bearing mice, XIAP inhibition acts in concert with TRAIL to cause even regression of established pancreatic carcinoma. Thus, this combination of XIAP inhibition plus TRAIL is a promising strategy to overcome apoptosis resistance of pancreatic cancer that warrants further investigation. [Cancer Res 2008;68(19):7956–65]
Data from Hepatitis B Virus–Associated Multistep Hepatocarcinogenesis: A Stepwise Increase in Allelic Alterations
Authors: Lee Joyce Man-Fong , Wong Chun-Ming , Ng Irene Oi-Lin
Published: March 2024

Abstract
Hepatocarcinogenesis is a multistep process, but systematic analysis using a genetic or molecular approach to accurately delineate the different stages of hepatocellular carcinoma (HCC) development is scarce. In this study, we used genome-wide allelotyping to systematically evaluate the allelic alterations in the multisteps of hepatitis B virus–associated hepatocarcinogenesis. The overall fractional allelic loss (FAL) indices of cirrhosis, dysplastic nodules (DN), and HCC were significantly different, with a clear stepwise increase (P < 0.001). Loss of heterozygosity (LOH) was uncommon in cirrhotic livers (n = 24; mean FAL index ± SD, 0.09 ± 0.09; median, 0.07). In contrast, LOH was common in our 74 HCC nodules, which were predominantly hepatitis B virus–associated (mean FAL index ± SD, 0.40 ± 0.23; median, 0.38). The 18 DNs had FAL index (mean ± SD, 0.27 ± 0.19; median, 0.20) in between that of cirrhosis and HCC. Importantly, high-grade DNs had FAL index significantly higher than that of low-grade DNs (P = 0.031) and close to that of HCC, indicating that high-grade DNs were genetically closer to HCC. However, there was no significant difference in FAL indices between primary HCCs and their corresponding intrahepatic metastases, but this absence of major allelic losses in this transformation to a metastatic phenotype does not exclude small-scale chromosomal losses or gene deletions. To conclude, hepatitis B virus–associated hepatocarcinogenesis is a multistep process accompanied by stepwise increase in allelic losses from cirrhosis and low- and high-grade DN to HCC. Such allelic losses contribute to promote tumor development and progression. [Cancer Res 2008;68(14):5988–96]
Data from Phosphatidylinositol 3-Kinase Hyperactivation Results in Lapatinib Resistance that Is Reversed by the mTOR/Phosphatidylinositol 3-Kinase Inhibitor NVP-BEZ235
Authors: Eichhorn Pieter J.A. , Gili Magüi , Scaltriti Maurizio , Serra Violeta , Guzman Marta , Nijkamp Wouter , Beijersbergen Roderick L. , Valero Vanesa , Seoane Joan , Bernards René , Baselga José
Published: March 2024

Abstract
Small molecule inhibitors of HER2 are clinically active in women with advanced HER2-positive breast cancer who have progressed on trastuzumab treatment. However, the effectiveness of this class of agents is limited by either primary resistance or acquired resistance. Using an unbiased genetic approach, we performed a genome wide loss-of-function short hairpin RNA screen to identify novel modulators of resistance to lapatinib, a recently approved anti-HER2 tyrosine kinase inhibitor. Here, we have identified the tumor suppressor PTEN as a modulator of lapatinib sensitivity in vitro and in vivo. In addition, we show that two dominant activating mutations in PIK3CA (E545K and H1047R), which are prevalent in breast cancer, also confer resistance to lapatinib. Furthermore, we show that phosphatidylinositol 3-kinase (PI3K)–induced lapatinib resistance can be abrogated through the use of NVP-BEZ235, a dual inhibitor of PI3K/mTOR. Our data show that deregulation of the PI3K pathway, either through loss-of-function mutations in PTEN or dominant activating mutations in PIK3CA, leads to lapatinib resistance, which can be effectively reversed by NVP-BEZ235. [Cancer Res 2008;68(22):9221–30]
Data from Amplification of Telomerase Reverse Transcriptase Gene in Human Mammary Epithelial Cells with Limiting Telomerase RNA Expression Levels
Authors: Cao Ying , Huschtscha Lily I. , Nouwens Amanda S. , Pickett Hilda A. , Neumann Axel A. , Chang Andy C-M. , Toouli Christian D. , Bryan Tracy M. , Reddel Roger R.
Published: March 2024

Abstract
Activation of telomerase is a crucial step during cellular immortalization, and in some tumors this results from amplification of the human telomerase reverse transcriptase (hTERT) gene. Immortalization of normal human cells has been achieved by transduction with hTERT cDNA under the control of a strong heterologous enhancer/promoter, but this is sometimes an inefficient process, with periods of poor growth or even crisis occurring before immortalization. Here, we showed that normal human mammary epithelial cells expressing exogenous hTERT amplified the transgene extensively and expressed high levels of hTERT mRNA and protein. Paradoxically, the cells had low levels of telomerase activity and very short telomeres, indicating that telomerase activity did not correlate with hTERT expression. These cells contained only ∼20 human telomerase RNA (hTR) molecules/cell (compared with ∼120 hTR molecules per 293 cell). Expression of exogenous hTR caused increased telomerase activity and telomere lengthening. These data indicate that some hTERT-transduced normal cells may express high levels of the transgene but fail to up-regulate endogenous hTR expression sufficiently to enable expression of robust levels of telomerase activity. [Cancer Res 2008;68(9):3115–23]
Data from Synergistic Proapoptotic Activity of Recombinant TRAIL Plus the Akt Inhibitor Perifosine in Acute Myelogenous Leukemia Cells
Authors: Tazzari Pier Luigi , Tabellini Giovanna , Ricci Francesca , Papa Veronica , Bortul Roberta , Chiarini Francesca , Evangelisti Camilla , Martinelli Giovanni , Bontadini Andrea , Cocco Lucio , McCubrey James A. , Martelli Alberto M.
Published: March 2024

Abstract
To potentiate the response of acute myelogenous leukemia (AML) cells to tumor necrosis factor–related apoptosis-inducing ligand (TRAIL) cytotoxicity, we have examined the efficacy of a combination with perifosine, a novel phosphatidylinositol-3-kinase (PI3K)/Akt signaling inhibitor. The rationale for using such a combination is that perifosine was recently described to increase TRAIL-R2 receptor expression and decrease the cellular FLICE-inhibitory protein (cFLIP) in human lung cancer cell lines. Perifosine and TRAIL both induced cell death by apoptosis in the THP-1 AML cell line, which is characterized by constitutive PI3K/Akt activation, but lacks functional p53. Perifosine, at concentrations below IC50, dephosphorylated Akt and increased TRAIL-R2 levels, as shown by Western blot, reverse transcription-PCR, and flow cytometric analysis. Perifosine also decreased the long isoform of cFLIP (cFLIP-L) and the X-linked inhibitor of apoptosis protein (XIAP) expression. Perifosine and TRAIL synergized to activate caspase-8 and induce apoptosis, which was blocked by a caspase-8–selective inhibitor. Up-regulation of TRAIL-R2 expression was dependent on a protein kinase Cα/c-Jun-NH2-kinase 2/c-Jun signaling pathway activated by perifosine through reactive oxygen species production. Perifosine also synergized with TRAIL in primary AML cells displaying constitutive activation of the Akt pathway by inducing apoptosis, Akt dephosphorylation, TRAIL-R2 up-regulation, cFLIP-L and XIAP down-regulation, and c-Jun phosphorylation. The combined treatment negatively affected the clonogenic activity of CD34+ cells from patients with AML. In contrast, CD34+ cells from healthy donors were resistant to perifosine and TRAIL treatment. Our findings suggest that the combination of perifosine and TRAIL might offer a novel therapeutic strategy for AML. [Cancer Res 2008;68(22):9394–403]
Data from Hepatocyte Growth Factor and Sonic Hedgehog Expression in Cerebellar Neural Progenitor Cells Costimulate Medulloblastoma Initiation and Growth
Authors: Binning Mandy J. , Niazi Toba , Pedone Carolyn A. , Lal Bachchu , Eberhart Charles G. , Kim K. Jin , Laterra John , Fults Daniel W.
Published: March 2024

Abstract
Medulloblastomas are malignant brain tumors that arise by transformation of neural progenitor cells in the cerebellum in children. Treatment-related neurotoxicity has created a critical need to identify signaling molecules that can be targeted therapeutically to maximize tumor growth suppression and minimize collateral neurologic injury. In genetically engineered mice, activation of Sonic Hedgehog (Shh) signaling in neural stem cells in the developing cerebellum induces medulloblastomas. Hepatocyte growth factor (HGF) and its cell surface receptor c-Met are highly expressed in human medulloblastomas, and elevated levels of c-Met and HGF mRNA predict an unfavorable prognosis for patients. HGF is neuroprotective for cerebellar granule cells and promotes growth of human medulloblastoma cells in culture and in murine xenografts. We modeled the ability of HGF to induce medulloblastomas in mice using a version of the RCAS/tv-a system that allows gene transfer to cerebellar neural progenitors during their postnatal expansion phase when these cells are highly susceptible to transformation. Here, we report a high frequency of medulloblastoma formation in mice after postnatal expression of HGF in cooperation with Shh. Some tumors showed neurocytic differentiation similar to that in human nodular medulloblastomas with activated Shh signaling. Systemic administration of a monoclonal antibody against HGF prolonged survival of mice bearing Shh + HGF–induced medulloblastomas by stimulating apoptosis. These findings indicate a role for HGF in medulloblastoma initiation and growth and show efficacy of HGF-targeted therapy in a mouse model of endogenously arising tumors. [Cancer Res 2008;68(19):7838–45]
Data from Combination Therapy with Cisplatin and Anti–4-1BB: Synergistic Anticancer Effects and Amelioration of Cisplatin-Induced Nephrotoxicity
Authors: Kim Young H. , Choi Beom K. , Kim Kwang H. , Kang Sang W. , Kwon Byoung S.
Published: March 2024

Abstract
Anti–4-1BB and cisplatin showed synergistic anticancer effects in the CT-26 colon carcinoma model, producing complete regression in >60% of mice with either preventive or therapeutic treatment. The tumor-free mice formed long-lasting CD8+ T cell–dependent tumor-specific memory. Anti–4-1BB induced rapid repopulation of T and B cells from cisplatin-mediated lymphopenia and differentiation and expansion of IFN-γ+CD11c+CD8+ T cells. Cisplatin facilitated expansion of naïve, effector, and memory CD8+ T cells; combination therapy produced almost twice as many lymphoid cells as anti–4-1BB alone. Cisplatin increased 4-1BB on antigen-primed T cells and induced 4-1BB de novo on kidney tubular epithelium. Cross-linking of 4-1BB protected the T cells and kidney epithelium from cisplatin-mediated apoptosis by increasing expression of antiapoptotic molecules. Thus, cisplatin-induced 4-1BB provided a mechanism for amelioration of the lymphopenia and nephrotoxicity inherent in cisplatin treatment. We concluded that chemoimmunotherapy with anti–4-1BB and cisplatin is synergistic in tumor killing and prevention of organ-specific toxicity. [Cancer Res 2008;68(18):7264–9]
Data from Serotonin Metabolism Is Dysregulated in Cholangiocarcinoma, which Has Implications for Tumor Growth
Authors: Alpini Gianfranco , Invernizzi Pietro , Gaudio Eugenio , Venter Julie , Kopriva Shelley , Bernuzzi Francesca , Onori Paolo , Franchitto Antonio , Coufal Monique , Frampton Gabriel , Alvaro Domenico , Lee Sum P. , Marzioni Marco , Benedetti Antonio , DeMorrow Sharon
Published: March 2024

Abstract
Cholangiocarcinoma is a devastating cancer of biliary origin with limited treatment options. Symptoms are usually evident after blockage of the bile duct by the tumor, and at this late stage, they are relatively resistant to chemotherapy and radiation therapy. Therefore, it is imperative that alternative treatment options are explored. We present novel data indicating that the metabolism of serotonin is dysregulated in cholangiocarcinoma cell lines, compared with normal cholangiocytes, and tissue and bile from cholangiocarcinoma patients. Specifically, there was an increased expression of tryptophan hydroxylase 1 and a suppression of monoamine oxidase A expression (enzymes responsible for the synthesis and degradation of serotonin, respectively) in cholangiocarcinoma. This resulted in an increased secretion of serotonin from cholangiocarcinoma and increased serotonin in the bile from cholangiocarcinoma patients. Increased local serotonin release may have implications on cholangiocarcinoma cell growth. Serotonin administration increased cholangiocarcinoma cell growth in vitro, whereas inhibition of serotonin synthesis decreases tumor cell growth both in vitro and in vivo. The data presented here represent the first evidence that serotonin metabolism is dysregulated in cholangiocarcinoma and that modulation of serotonin synthesis may represent an alternative target for the development of therapeutic strategies. [Cancer Res 2008;68(22):9184–93]
Data from How Dysregulated Colonic Crypt Dynamics Cause Stem Cell Overpopulation and Initiate Colon Cancer
Authors: Boman Bruce M. , Fields Jeremy Z. , Cavanaugh Kenneth L. , Guetter Arthur , Runquist Olaf A.
Published: March 2024

Abstract
Based on investigation of the earliest colonic tissue alteration in familial adenomatous polyposis (FAP) patients, we present the hypothesis that initiation of colorectal cancer by adenomatous polyposis coli (APC) mutation is mediated by dysregulation of two cellular mechanisms. One involves differentiation, which normally decreases the proportion (proliferative fraction) of colonic crypt cells that can proliferate; the other is a cell cycle mechanism that simultaneously increases the probability that proliferative cells are in S phase. In normal crypts, stem cells (SC) at the crypt bottom generate rapidly proliferating cells, which undergo differentiation while migrating up the crypt. Our modeling of normal crypts suggests that these transitions are mediated by mechanisms that regulate proliferative fraction and S-phase probability. In FAP crypts, the population of rapidly proliferating cells is shifted upwards, as indicated by the labeling index (LI; i.e., crypt distribution of cells in S phase). Our analysis of FAP indicates that these transitions are delayed because the proliferative fraction and S-phase probability change more slowly as a function of crypt level. This leads to expansion of the proliferative cell population, including a subpopulation that has a low frequency of S-phase cells. We previously reported that crypt SC overpopulation explains the LI shift. Here, we determine that SCs (or cells having high stemness) are proliferative cells with a low probability of being in S phase. Thus, dysregulation of mechanisms that control proliferative fraction and S-phase probability explains how APC mutations induce SC overpopulation at the crypt bottom, shift the rapidly proliferating cell population upwards, and initiate colon tumorigenesis. [Cancer Res 2008;68(9):3304–13]
Data from Combination Therapies against Chronic Myeloid Leukemia: Short-term versus Long-term Strategies
Authors: Komarova Natalia L. , Wodarz Dominik
Published: March 2024

Abstract
During therapy for chronic myeloid leukemia (CML), decline of the number of BCR-ABL transcripts has been shown to follow a biphasic pattern, with a fast phase followed by a slower phase. Hence, sustained remission requires a long phase of therapy. Data indicate that a combination of different available targeted drugs might prevent treatment failure due to drug resistance, especially at advanced stages of the disease. However, for long-term multiple-drug treatments, complications can arise from side effects. We investigate whether and how the number of drugs could be reduced during long-term therapy. Using computational models, we show that one or more drugs can be removed once the number of tumor cells is reduced significantly, without compromising the chances of sustained tumor suppression. Which drug to remove first depends on the number of mutations in the BCR-ABL gene that confer resistance to the drugs, as well as on how effectively the drugs inhibit Bcr-Abl protein tyrosine kinase activity and inhibit tumor growth. We further show that the number of CML cells at which the number of drugs can be reduced does not correlate with the two phases of decline of the BCR-ABL transcript numbers. Neither does it depend much on kinetic parameters of CML growth, except for the mutation rates at which resistance is generated. This is a significant finding because even without any information on most parameters, and using only the data on the number of cancer cells and the rate at which resistant mutants are generated, it is possible to predict at which stage of treatment the number of drugs can be reduced. [Cancer Res 2009;69(11):4904–10]
Data from Estrogen-Related Receptor α Is Critical for the Growth of Estrogen Receptor–Negative Breast Cancer
Authors: Stein Rebecca A. , Chang Ching-yi , Kazmin Dmitri A. , Way James , Schroeder Thies , Wergin Melanie , Dewhirst Mark W. , McDonnell Donald P.
Published: March 2024

Abstract
Expression of estrogen-related receptor α (ERRα) has recently been shown to carry negative prognostic significance in breast and ovarian cancers. The specific role of this orphan nuclear receptor in tumor growth and progression, however, is yet to be fully understood. The significant homology between estrogen receptor α (ERα) and ERRα initially suggested that these receptors may have similar transcriptional targets. Using the well-characterized ERα-positive MCF-7 breast cancer cell line, we sought to gain a genome-wide picture of ERα-ERRα cross-talk using an unbiased microarray approach. In addition to generating a host of novel ERRα target genes, this study yielded the surprising result that most ERRα-regulated genes are unrelated to estrogen signaling. The relatively small number of genes regulated by both ERα and ERRα led us to expand our study to the more aggressive and less clinically treatable ERα-negative class of breast cancers. In this setting, we found that ERRα expression is required for the basal level of expression of many known and novel ERRα target genes. Introduction of a small interfering RNA directed to ERRα into the highly aggressive breast carcinoma MDA-MB-231 cell line dramatically reduced the migratory potential of these cells. Although stable knockdown of ERRα expression in MDA-MB-231 cells had no effect on in vitro cell proliferation, a significant reduction of tumor growth rate was observed when these cells were implanted as xenografts. Our results confirm a role for ERRα in breast cancer growth and highlight it as a potential therapeutic target for estrogen receptor–negative breast cancer. [Cancer Res 2008;68(21):8805–12]
Data from Inhibition of Repair of Radiation-Induced DNA Damage Enhances Gene Expression from Replication-Defective Adenoviral Vectors
Authors: Hingorani Mohan , White Christine L. , Merron Andrew , Peerlinck Inge , Gore Martin E. , Slade Andrew , Scott Simon D. , Nutting Christopher M. , Pandha Hardev S. , Melcher Alan A. , Vile Richard G. , Vassaux Georges , Harrington Kevin J.
Published: March 2024

Abstract
Radiation has been shown to up-regulate gene expression from adenoviral vectors in previous studies. In the current study, we show that radiation-induced dsDNA breaks and subsequent signaling through the mitogen-activated protein kinase (MAPK) pathway are responsible, at least in part, for this enhancement of transgene expression both in vitro and in vivo. Inhibitors of ataxia-telangiectasia–mutated, poly(ADP-ribose) polymerase–mutated, and DNA-dependent protein kinase (DNA-PK)–mediated DNA repair were shown to maintain dsDNA breaks (γH2AX foci) by fluorescence-activated cell sorting and microscopy. Inhibition of DNA repair was associated with increased green fluorescent protein (GFP) expression from a replication-defective adenoviral vector (Ad-CMV-GFP). Radiation-induced up-regulation of gene expression was abrogated by inhibitors of MAPK (PD980059 and U0126) and phosphatidylinositol 3-kinase (LY294002) but not by p38 MAPK inhibition. A reporter plasmid assay in which GFP was under the transcriptional control of artificial Egr-1 or cytomegalovirus promoters showed that the DNA repair inhibitors increased GFP expression only in the context of the Egr-1 promoter. In vivo administration of a water-soluble DNA-PK inhibitor (KU0060648) was shown to maintain luciferase expression in HCT116 xenografts after intratumoral delivery of Ad-RSV-Luc. These data have important implications for therapeutic strategies involving multimodality use of radiation, targeted drugs, and adenoviral gene delivery and provide a framework for evaluating potential advantageous combinatorial effects. [Cancer Res 2008;68(23):9771–8]
Data from TSU68 Prevents Liver Metastasis of Colon Cancer Xenografts by Modulating the Premetastatic Niche
Authors: Yamamoto Masayoshi , Kikuchi Hirotoshi , Ohta Manabu , Kawabata Toshiki , Hiramatsu Yoshihiro , Kondo Kenji , Baba Megumi , Kamiya Kinji , Tanaka Tatsuo , Kitagawa Masatoshi , Konno Hiroyuki
Published: March 2024

Abstract
The aim of this study was to investigate the inhibitory effect of TSU68 [(Z)-5-[(1,2-dihydro-2-oxo-3H-indol-3-ylidene)methyl]-2,4-dimethyl-1H-pyrrole-3-propanoic acid; SU6668], an inhibitor of vascular endothelial growth factor receptor 2, platelet-derived growth factor receptor β, and fibroblast growth factor receptor 1 (FGFR1), on colon cancer liver metastasis, and to test the hypothesis that TSU68 modulates the microenvironment in the liver before the formation of metastasis. First, we implanted the highly metastatic human colon cancer TK-4 orthotopically into the cecal walls of nude mice, followed by twice-daily administration of TSU68 (400 mg/kg/d) or vehicle. Five weeks of treatment with TSU68 significantly inhibited liver metastasis compared with the control group (P < 0.001). Next, we analyzed the gene expression profile in premetastatic liver using microarrays. Microarray and quantitative reverse transcription-PCR analysis showed that mRNA levels for the chemokine CXCL1 were significantly increased in tumor-bearing mice compared with non–tumor-bearing mice. Moreover, CXCL1 expression was significantly decreased by TSU68 treatment. CXCR2 expression was detected predominantly on tumor cells in orthotopic tumors compared with ectopic tumors. The number of migrating neutrophils in premetastatic liver was significantly decreased in the TSU68-treated group (P < 0.001). The amount of interleukin-12 (IL-12) p40 in the portal vein was significantly decreased by TSU68 (P = 0.02). Blockade of both CXCR2 and IL-12 p40 with a neutralizing antibody significantly inhibited liver metastasis. These results suggest that the CXCL1/CXCR2 axis is important in cancer metastasis and that TSU68 may modulate the premetastatic niche in the target organ through suppression of the inflammatory response, which might be an alternative mechanism used by antiangiogenic agents. [Cancer Res 2008;68(23):9754–62]
Data from Carcinoma-Associated Fibroblast–Like Differentiation of Human Mesenchymal Stem Cells
Authors: Mishra Pravin J. , Mishra Prasun J. , Humeniuk Rita , Medina Daniel J. , Alexe Gabriela , Mesirov Jill P. , Ganesan Sridhar , Glod John W. , Banerjee Debabrata
Published: March 2024

Abstract
Carcinoma-associated fibroblasts (CAF) have recently been implicated in important aspects of epithelial solid tumor biology, such as neoplastic progression, tumor growth, angiogenesis, and metastasis. However, neither the source of CAFs nor the differences between CAFs and fibroblasts from nonneoplastic tissue have been well defined. In this study, we show that human bone marrow–derived mesenchymal stem cells (hMSCs) exposed to tumor-conditioned medium (TCM) over a prolonged period of time assume a CAF-like myofibroblastic phenotype. More importantly, these cells exhibit functional properties of CAFs, including sustained expression of stromal-derived factor-1 (SDF-1) and the ability to promote tumor cell growth both in vitro and in an in vivo coimplantation model, and expression of myofibroblast markers, including α-smooth muscle actin and fibroblast surface protein. hMSCs induced to differentiate to a myofibroblast-like phenotype using 5-azacytidine do not promote tumor cell growth as efficiently as hMSCs cultured in TCM nor do they show increased SDF-1 expression. Furthermore, gene expression profiling revealed similarities between TCM-exposed hMSCs and CAFs. Taken together, these data suggest that hMSCs are a source of CAFs and can be used in the modeling of tumor-stroma interactions. To our knowledge, this is the first report showing that hMSCs become activated and resemble carcinoma-associated myofibroblasts on prolonged exposure to conditioned medium from MDAMB231 human breast cancer cells. [Cancer Res 2008;68(11):4331–9]
Data from Secondary BRCA1 Mutations in BRCA1-Mutated Ovarian Carcinomas with Platinum Resistance
Authors: Swisher Elizabeth M. , Sakai Wataru , Karlan Beth Y. , Wurz Kaitlyn , Urban Nicole , Taniguchi Toshiyasu
Published: March 2024

Abstract
Although ovarian carcinomas with mutated BRCA1 or BRCA2 are sensitive to platinum compounds, such carcinomas eventually develop platinum resistance. Previously, we showed that acquired resistance to cisplatin in BRCA2-mutated tumors can be mediated by secondary intragenic mutations in BRCA2 that restore the wild-type BRCA2 reading frame. Here, we show that secondary mutations of BRCA1 also occur in BRCA1-mutated ovarian cancer with platinum resistance. We evaluated nine recurrent BRCA1-mutated ovarian cancers previously treated with platinum compounds, including five with acquired platinum resistance, one with primary platinum resistance, and three with platinum sensitivity. Four of the six recurrent platinum-resistant tumors had developed secondary genetic changes in BRCA1 that restored the reading frame of the BRCA1 protein, whereas none of the three platinum-sensitive recurrent tumors developed BRCA1 sequence alterations. We immunohistochemically confirmed restored expression of BRCA1 protein in two cases with secondary mutations. Intriguingly, the case with primary platinum resistance showed back mutation of BRCA1 in the primary tumor and showed another secondary mutation in the recurrent tumor. Our results suggest that secondary mutations in BRCA1 can mediate resistance to platinum in BRCA1-mutated ovarian tumors. [Cancer Res 2008;68(8):2581–6]
Data from Tumor Protein 53–Induced Nuclear Protein 1 Is a Major Mediator of p53 Antioxidant Function
Authors: Cano Carla E. , Gommeaux Julien , Pietri Sylvia , Culcasi Marcel , Garcia Stéphane , Seux Mylène , Barelier Sarah , Vasseur Sophie , Spoto Rose P. , Pébusque Marie-Josèphe , Dusetti Nelson J. , Iovanna Juan L. , Carrier Alice
Published: March 2024

Abstract
p53 exerts its tumor suppressor function mainly through transcriptional induction of target genes involved in several processes, including cell cycle checkpoints, apoptosis, and regulation of cell redox status. p53 antioxidant function is dependent on its transcriptional activity and proceeds by sequential induction of antioxidant and proapoptotic targets. However, none of the thus far renowned p53 targets have proved able to abolish on their own the intracellular reactive oxygen species (ROS) accumulation caused by p53 deficiency, therefore pointing to the existence of other prominent and yet unknown p53 antioxidant targets. Here, we show that TP53INP1 represents such a target. Indeed, TP53INP1 transcript induction on oxidative stress is strictly dependent on p53. Mouse embryonic fibroblasts (MEF) and splenocytes derived from TP53INP1-deficient (inp1−/−) mice accumulate intracellular ROS, whereas overexpression of TP53INP1 in p53-deficient MEFs rescues ROS levels to those of p53-proficient cells, indicating that TP53INP1 antioxidant function is p53 independent. Furthermore, accumulation of ROS in inp1−/− cells on oxidant challenge is associated with decreased expression of p53 targets p21/Cdkn1a, Sesn2, TAp73, Puma, and Bax. Mutation of p53 Ser58 (equivalent to human p53 Ser46) abrogates transcription of these genes, indicating that TP53INP1-mediated p53 Ser58 phosphorylation is implicated in this process. In addition, TP53INP1 deficiency results in an antioxidant (N-acetylcysteine)-sensitive acceleration of cell proliferation. Finally, TP53INP1 deficiency increases oxidative stress–related lymphoma incidence and decreases survival of p53+/− mice. In conclusion, our data show that TP53INP1 is a major actor of p53-driven oxidative stress response that possesses both a p53-independent intracellular ROS regulatory function and a p53-dependent transcription regulatory function. [Cancer Res 2009;69(1):219–26]