bluuebunny/crossref_metadata_2025 huggingface dataset:
Data from Targeting Cancer Stem Cells through L1CAM Suppresses Glioma Growth
Authors: Bao Shideng , Wu Qiulian , Li Zhizhong , Sathornsumetee Sith , Wang Hui , McLendon Roger E. , Hjelmeland Anita B. , Rich Jeremy N.
Published: March 2024

Abstract
Malignant gliomas are lethal cancers that display striking cellular heterogeneity. A highly tumorigenic glioma tumor subpopulation, termed cancer stem cells or tumor-initiating cells, promotes therapeutic resistance and tumor angiogenesis. Therefore, targeting cancer stem cells may improve patient survival. We interrogated the role of a neuronal cell adhesion molecule, L1CAM, in glioma stem cells as L1CAM regulates brain development and is expressed in gliomas. L1CAM+ and CD133+ cells cosegregated in gliomas, and levels of L1CAM were higher in CD133+ glioma cells than normal neural progenitors. Targeting L1CAM using lentiviral-mediated short hairpin RNA (shRNA) interference in CD133+ glioma cells potently disrupted neurosphere formation, induced apoptosis, and inhibited growth specifically in glioma stem cells. We identified a novel mechanism for L1CAM regulation of cell survival as L1CAM knockdown decreased expression of the basic helix-loop-helix transcription factor Olig2 and up-regulated the p21WAF1/CIP1 tumor suppressor in CD133+ glioma cells. To determine if targeting L1CAM was sufficient to reduce glioma stem cell tumor growth in vivo, we targeted L1CAM in glioma cells before injection into immunocompromised mice or directly in established tumors. In each glioma xenograft model, shRNA targeting of L1CAM expression in vivo suppressed tumor growth and increased the survival of tumor-bearing animals. Together, these data show that L1CAM is required for maintaining the growth and survival of CD133+ glioma cells both in vitro and in vivo, and L1CAM may represent a cancer stem cell–specific therapeutic target for improving the treatment of malignant gliomas and other brain tumors. [Cancer Res 2008;68(15):6043–8]
Data from Androgenic Control of Transforming Growth Factor-β Signaling in Prostate Epithelial Cells through Transcriptional Suppression of Transforming Growth Factor-β Receptor II
Authors: Song Kyung , Wang Hui , Krebs Tracy L. , Kim Seong-Jin , Danielpour David
Published: March 2024

Abstract
The androgen receptor cross-talks with transforming growth factor-β (TGF-β) through mechanisms that remain poorly understood. Here we provide strong evidence that 5α-dihydrotestosterone (DHT) intercepts the ability of prostate epithelial cells to undergo TGF-β–induced apoptosis, and present a new model for this androgenic effect. We report that DHT decreases the level of TGF-β receptor II (TβRII) through a transcriptional mechanism, leading to suppression of the ability of TGF-β to down-regulate expression of Bcl-xL and cyclin Ds, activate caspase-3, and induce apoptosis. Promoter analysis, DNA pulldown, and electrophoretic mobility shift assays support that transcriptional down-regulation of TβRII by DHT occurs through Sp1/Sp3 response elements, with the binding of Sp1 to the TβRII promoter being suppressed by DHT, largely driven by loss of Sp1 protein and/or activity. These results provide fresh insight on the mechanism of growth control by androgens and the progression of prostate cancer to androgen independence. [Cancer Res 2008;68(19):8173–82]
Data from Identification of Novel Alternative Splice Isoforms of Circulating Proteins in a Mouse Model of Human Pancreatic Cancer
Authors: Menon Rajasree , Zhang Qing , Zhang Yan , Fermin Damian , Bardeesy Nabeel , DePinho Ronald A. , Lu Chunxia , Hanash Samir M. , Omenn Gilbert S. , States David J.
Published: March 2024

Abstract
To assess the potential of tumor-associated, alternatively spliced gene products as a source of biomarkers in biological fluids, we have analyzed a large data set of mass spectra derived from the plasma proteome of a mouse model of human pancreatic ductal adenocarcinoma. MS/MS spectra were interrogated for novel splice isoforms using a nonredundant database containing an exhaustive three-frame translation of Ensembl transcripts and gene models from ECgene. This integrated analysis identified 420 distinct splice isoforms, of which 92 did not match any previously annotated mouse protein sequence. We chose seven of those novel variants for validation by reverse transcription–PCR. The results were concordant with the proteomic analysis. All seven novel peptides were successfully amplified in pancreas specimens from both wild-type and mutant mice. Isotopic labeling of cysteine-containing peptides from tumor-bearing mice and wild-type controls enabled relative quantification of the proteins. Differential expression between tumor-bearing and control mice was notable for peptides from novel variants of muscle pyruvate kinase, malate dehydrogenase 1, glyceraldehyde-3-phosphate dehydrogenase, proteoglycan 4, minichromosome maintenance, complex component 9, high mobility group box 2, and hepatocyte growth factor activator. Our results show that, in a mouse model for human pancreatic cancer, novel and differentially expressed alternative splice isoforms are detectable in plasma and may be a source of candidate biomarkers. [Cancer Res 2009;69(1):300–9]
Data from Pituitary Tumor-Transforming 1 Increases Cell Motility and Promotes Lymph Node Metastasis in Esophageal Squamous Cell Carcinoma
Authors: Ito Tetsuo , Shimada Yutaka , Kan Takatsugu , David Stefan , Cheng Yulan , Mori Yuriko , Agarwal Rachana , Paun Bogdan , Jin Zhe , Olaru Alexandru , Hamilton James P. , Yang Jian , Abraham John M. , Meltzer Stephen J. , Sato Fumiaki
Published: March 2024

Abstract
Human pituitary tumor-transforming 1 (PTTG1)/securin is a putative oncoprotein that is overexpressed in various tumor types. However, the involvement of PTTG1 in gastrointestinal cancer development and progression remains unclear. In this study, we investigated the clinical significance and biological effects of PTTG1 in esophageal squamous cell carcinoma (ESCC). Immunohistochemical studies performed on 113 primary ESCC specimens revealed a high prevalence of PTTG1 overexpression (60.2%), which was significantly associated with lymph node metastasis (regional, P = 0.042; distant, P = 0.005), advanced tumor stage (P = 0.028), and poorer overall survival (P = 0.017, log-rank test; P = 0.044, Cox proportional hazard model). Eleven ESCC cell lines expressed PTTG1 protein at levels 2.4 to 6.6 times higher than those in normal esophageal epithelial cells (HEEpiC). PTTG1 protein expression was confined to the nucleus in HEEpiC cells but present in both the cytoplasm and nucleus in ESCC cells. Two small interfering RNAs (siRNA) inhibited PTTG1 mRNA and protein expression in three ESCC cell lines by 77% to 97%. In addition, PTTG1 down-regulation by these siRNAs significantly reduced cell motility in all three ESCC cell lines (P < 0.01) in vitro, as well as popliteal lymph node metastases of ESCC cells in nude mice (P = 0.020). Global gene expression profiling suggested that several members of the Ras and Rho gene families, including RRAS, RHOG, ARHGAP1, and ARHGADIA, represented potential downstream genes in the PTTG1 pathway. Taken together, these findings suggest that PTTG1 overexpression promotes cell motility and lymph node metastasis in ESCC patients, leading to poorer survival. Thus, PTTG1 constitutes a potential biomarker and therapeutic target in ESCCs with lymph node metastases. [Cancer Res 2008;68(9):3214–24]
Data from Cyclin-Dependent Kinase-3–Mediated c-Jun Phosphorylation at Ser63 and Ser73 Enhances Cell Transformation
Authors: Cho Yong-Yeon , Tang Faqing , Yao Ke , Lu Chengrong , Zhu Feng , Zheng Duo , Pugliese Angelo , Bode Ann M. , Dong Zigang
Published: March 2024

Abstract
c-Jun is a component of the activator protein-1 (AP-1) complex, which plays a crucial role in the regulation of gene expression, cell proliferation, and cell transformation, as well as cancer development. Herein, we found that cyclin-dependent kinase (Cdk)-3, but not Cdk2 or c-Jun NH2-terminal kinase, is a novel kinase of c-Jun induced by stimulation with growth factors such as epidermal growth factor (EGF). Cdk3 was shown to phosphorylate c-Jun at Ser63 and Ser73 in vitro and ex vivo. EGF-induced Cdk3 activation caused c-Jun phosphorylation at Ser63 and Ser73, resulting in increased AP-1 transactivation. Ectopic expression of Cdk3 resulted in anchorage-independent cell transformation of JB6 Cl41 cells induced by EGF and foci formation stimulated by constitutively active Ras (RasG12V), which was mediated by AP-1 in NIH3T3 cells. These results showed that the Cdk3/c-Jun signaling axis plays an important role in EGF-stimulated cell proliferation and cell transformation. [Cancer Res 2009;69(1):272–81]
Data from Prediction of Cancer Driver Mutations in Protein Kinases
Authors: Torkamani Ali , Schork Nicholas J.
Published: March 2024

Abstract
A large number of somatic mutations accumulate during the process of tumorigenesis. A subset of these mutations contribute to tumor progression (known as “driver” mutations) whereas the majority of these mutations are effectively neutral (known as “passenger” mutations). The ability to differentiate between drivers and passengers will be critical to the success of upcoming large-scale cancer DNA resequencing projects. Here we show a method capable of discriminating between drivers and passengers in the most frequently cancer-associated protein family, protein kinases. We apply this method to multiple cancer data sets, validating its accuracy by showing that it is capable of identifying known drivers, has excellent agreement with previous statistical estimates of the frequency of drivers, and provides strong evidence that predicted drivers are under positive selection by various sequence and structural analyses. Furthermore, we identify particular positions in protein kinases that seem to play a role in oncogenesis. Finally, we provide a ranked list of candidate driver mutations. [Cancer Res 2008;68(6):1675–82]
Data from Crosstalk between the Androgen Receptor and β-Catenin in Castrate-Resistant Prostate Cancer
Authors: Wang Gang , Wang Jun , Sadar Marianne D.
Published: March 2024

Abstract
The androgen-signaling pathway plays an important role in the development and hormonal progression of prostate cancer to the castrate-resistant stage (also called androgen-independent or hormone refractory). The Wnt pathway and β-catenin contribute to prostate biology and pathology. Here application of Affymetrix GeneChip analysis revealed the genomic similarity of the LNCaP hollow fiber model to clinical samples and identified genes with differential expression during hormonal progression. The fiber model samples clustered according to the expression profile of androgen-regulated genes to provide genomic evidence for the reactivation of the AR signaling pathway in castrate-resistant prostate cancer. Pathway-based characterization of gene expression identified activation of the Wnt pathway. Together with the increased expression of AR and β-catenin, there was increased nuclear colocalization and interaction of endogenous AR and β-catenin in castrate-resistant prostate cancer from castrated mice. Surprisingly, no interaction or colocalization of AR and β-catenin could be detected in xenografts from noncastrated mice. These studies provide the first in vivo evidence to support aberrant activation of the AR through the Wnt/β-catenin signaling pathway during progression of prostate cancer to the terminal castrate-resistant stage. [Cancer Res 2008;68(23):9918–27]
Data from Transcriptional Output of the Salvador/Warts/Hippo Pathway Is Controlled in Distinct Fashions in Drosophila melanogaster and Mammalian Cell Lines
Authors: Zhang Xiaomeng , Milton Claire C. , Humbert Patrick O. , Harvey Kieran F.
Published: March 2024

Abstract
The Salvador/Warts/Hippo (SWH) pathway is an important modulator of organ size, and deregulation of pathway activity can lead to cancer. Several SWH pathway components are mutated or expressed at altered levels in different human tumors including NF2, LATS1, LATS2, SAV1, and YAP. The SWH pathway regulates tissue growth by restricting the activity of the transcriptional coactivator protein known as Yorkie (Yki) in Drosophila melanogaster and Yes-associated protein (YAP) in mammals. Yki/YAP drives tissue growth in partnership with the Scalloped (Sd)/TEAD1-4 transcription factors. Yki/YAP also possesses two WW domains, which contact several proteins that have been suggested to either promote or inhibit the ability of Yki to induce transcription. To investigate the regulatory role of the Yki/YAP WW domains, we analyzed the functional consequence of mutating these domains. WW domain mutant YAP promoted transformation and migration of breast epithelial cells with increased potency, suggesting that WW domains mediate the inhibitory regulation of YAP in these cells. By contrast, the WW domains were required for YAP to promote NIH-3T3 cell transformation and for the ability of Yki to drive tissue growth in D. melanogaster and optimally activate Sd. This shows that Yki/YAP WW domains have distinct regulatory roles in different cell types and implies the existence of proteins that promote tissue growth in collaboration with Yki and Sd. [Cancer Res 2009;69(15):6033–41]
Data from Down-regulation of Rap1GAP via Promoter Hypermethylation Promotes Melanoma Cell Proliferation, Survival, and Migration
Authors: Zheng Hong , Gao Ling , Feng Yunfeng , Yuan Liya , Zhao Haibo , Cornelius Lynn A.
Published: March 2024

Abstract
Melanoma is the most serious, highly aggressive form of skin cancer with recent dramatic increases in incidence. Current therapies are relatively ineffective, highlighting the need for a better understanding of the molecular mechanisms contributing to the disease. We have previously shown that activation of Rap1 promotes melanoma cell proliferation and migration through the mitogen-activated protein kinase pathway and integrin activation. In the present study, we show that expression of Rap1GAP, a specific negative regulator of Rap1, is decreased in human melanoma tumors and cell lines. Overexpression of Rap1GAP in melanoma cells blocks Rap1 activation and extracellular signal-regulated kinase (ERK) phosphorylation and inhibits melanoma cell proliferation and survival. In addition, overexpression of Rap1GAP also inhibits focal adhesion formation and decreases melanoma cell migration. Rap1GAP down-regulation is due to its promoter methylation, a mechanism of gene silencing in tumors. Furthermore, treatment of melanoma cells with the demethylating agent 5-aza-2'-deoxycytidine reinduces Rap1GAP expression, followed by decreased Rap1 activity, ERK phosphorylation, and cell proliferation and survival—changes that are significantly blunted in cells transfected by small interfering RNA–mediated Rap1GAP knockdown. Taken together, our findings indicate that down-regulation of Rap1GAP via promoter hypermethylation promotes melanoma cell proliferation, survival, and migration. [Cancer Res 2009;69(2):449–57]
Data from Identification of Nectin-4 Oncoprotein as a Diagnostic and Therapeutic Target for Lung Cancer
Authors: Takano Atsushi , Ishikawa Nobuhisa , Nishino Ryohei , Masuda Ken , Yasui Wataru , Inai Kouki , Nishimura Hitoshi , Ito Hiroyuki , Nakayama Haruhiko , Miyagi Yohei , Tsuchiya Eiju , Kohno Nobuoki , Nakamura Yusuke , Daigo Yataro
Published: March 2024

Abstract
Gene expression profile analysis of lung cancers revealed the transactivation of an immunoglobulin-like molecule Nectin-4 in the majority of non–small cell lung cancers (NSCLC). Immunohistochemical staining of 422 NSCLCs showed that a high level of Nectin-4 expression was associated with poor prognosis for NSCLC patients (P < 0.0001), and multivariate analysis confirmed its independent prognostic value (P < 0.0001). We established an ELISA to measure serum Nectin-4 and found that serum Nectin-4 levels were significantly higher in NSCLC patients than in healthy volunteers. The proportion of the serum Nectin-4–positive cases was 88 of 164 (53.7%) NSCLCs, whereas only 3 of 131 (2.3%) healthy volunteers were falsely diagnosed as positive, which was superior to carcinoembryonic antigen (CEA) and cytokeratin 19-fragment (CYFRA21-1) in sensitivity and specificity. A combined ELISA for both Nectin-4 and CEA increased sensitivity and classified 65.0% of lung adenocarcinomas as positive with false-positive rate of 4.6%. The use of both Nectin-4 and CYFRA21-1 classified 68.3% of lung squamous cell carcinomas as positive with false-positive rate of 6.1%. Treatment of lung cancer cells with small interfering RNAs against Nectin-4 suppressed its expression and cell growth. In addition, exogenous expression of Nectin-4 increased the lamellipodia formation and the invasive ability of mammalian cells through activation of small GTPase Rac1. Nectin-4 might play a significant role in lung carcinogenesis, and it should be a new candidate serum and tissue biomarker, as well as a therapeutic target. [Cancer Res 2009;69(16):6694–703]
Data from Progressive Tumor Formation in Mice with Conditional Deletion of TGF-β Signaling in Head and Neck Epithelia Is Associated with Activation of the PI3K/Akt Pathway
Authors: Bian Yansong , Terse Anita , Du Juan , Hall Bradford , Molinolo Alfredo , Zhang Pin , Chen Wanjun , Flanders Kathleen C. , Gutkind J. Silvio , Wakefield Lalage M. , Kulkarni Ashok B.
Published: March 2024

Abstract
The precise role of transforming growth factor (TGF)-β signaling in head and neck squamous cell carcinoma (SCC) is not yet fully understood. Here, we report generation of an inducible head- and neck-specific knockout mouse model by crossing TGF-β receptor I (Tgfbr1) floxed mice with K14-CreERtam mice. By applying tamoxifen to oral cavity of the mouse to induce Cre expression, we were able to conditionally delete Tgfbr1 in the mouse head and neck epithelia. On tumor induction with 7,12-dimethylbenz(a)anthracene (DMBA), 45% of Tgfbr1 conditional knockout (cKO) mice (n = 42) developed SCCs in the head and neck area starting from 16 weeks after treatment. However, no tumors were observed in the control littermates. A molecular analysis revealed an enhanced proliferation and loss of apoptosis in the basal layer of the head and neck epithelia of Tgfbr1 cKO mice 4 weeks after tamoxifen and DMBA treatment. The most notable finding of our study is that the phosphoinositide 3-kinase (PI3K)/Akt pathway was activated in SCCs that developed in the Tgfbr1 cKO mice on inactivation of TGF-β signaling through Smad2/3 and DMBA treatment. These observations suggest that activation of Smad-independent pathways may contribute cooperatively with inactivation of Smad-dependent pathways to promote head and neck carcinogenesis in these mice. Our results revealed the critical role of the TGF-β signaling pathway and its cross-talk with the PI3K/Akt pathway in suppressing head and neck carcinogenesis. [Cancer Res 2009;69(14):5918–26]
Data from Ewing Sarcoma Fusion Protein EWSR1/FLI1 Interacts with EWSR1 Leading to Mitotic Defects in Zebrafish Embryos and Human Cell Lines
Authors: Embree Lisa J. , Azuma Mizuki , Hickstein Dennis D.
Published: March 2024

Abstract
The mechanism whereby the fusion of EWSR1 with the ETS transcription factor FLI1 contributes to malignant transformation in Ewing sarcoma remains unclear. We show that injection of human or zebrafish EWSR1/FLI1 mRNA into developing zebrafish embryos leads to mitotic defects with multipolar and disorganized mitotic spindles. Expression of human EWSR1/FLI1 in HeLa cells also results in mitotic defects, along with mislocalization of Aurora kinase B, a key regulator of mitotic progression. Because these mitotic abnormalities mimic those observed with the knockdown of EWSR1 in zebrafish embryos and HeLa cells, we investigated whether EWSR1/FLI1 interacts with EWSR1 and interferes with its function. EWSR1 coimmunoprecipitates with EWSR1/FLI1, and overexpression of EWSR1 rescues the mitotic defects in EWSR1/FLI1-transfected HeLa cells. This interaction between EWSR1/FLI1 and EWSR1 in Ewing sarcoma may induce mitotic defects leading to genomic instability and subsequent malignant transformation. [Cancer Res 2009;69(10):4363–71]
Data from Genetic Variants on Chromosome 15q25 Associated with Lung Cancer Risk in Chinese Populations
Authors: Wu Chen , Hu Zhibin , Yu Dianke , Huang Liming , Jin Guangfu , Liang Jie , Guo Huan , Tan Wen , Zhang Mingfeng , Qian Ji , Lu Daru , Wu Tangchun , Lin Dongxin , Shen Hongbing
Published: March 2024

Abstract
Recent three genome-wide association studies have mapped a lung cancer susceptibility locus to chromosome 15q25 in Caucasians. However, the reported risk single nucleotide polymorphisms (SNPs) are extremely rare in Asians, arguing against any of these being causative variants. This study sought to identify other variants on 15q25 associated with lung cancer susceptibility in Chinese. Two-stage case-control studies were conducted in subjects derived from both Northern and Southern China. The first-stage, consisting of 576 cases and 576 controls, was to discover novel risk variants using a haplotype-tagging SNP approach, and these variants were then replicated in the second-stage, consisting of 2,989 cases and 2,880 controls. Associations were estimated by logistic regression models, and function of the variants was examined by biochemical assays. We found that the three risk SNPs reported in Caucasians were not associated with lung cancer risk in Chinese. However, we identified four novel SNPs (rs2036534C>T, rs667282C>T, rs12910984G>A, and rs6495309T>C) that were associated with significantly increased lung cancer risk and smoking behavior, which were all confirmed in the replication analyses [odds ratios (95% confidence intervals) in the dominant model: 1.39 (1.23–1.57; P = 2.3 × 10−7), 1.52 (1.35–1.71; P = 2.0 × 10−12), 1.44 (1.28–1.63; P = 2.7 × 10−9), and 1.43 (1.27–1.61; P = 2.6 × 10−9), respectively]. We characterized the rs6495309T>C change in the CHRNA3 promoter as a functional variant because it affected the Oct-1 binding ability, resulting in increased CHRNA3 expression. These results support 15q25 as a susceptibility region for lung cancer in Chinese but underscore the difference in genetic markers among different ethnic populations. [Cancer Res 2009;69(12):5065–72]
Data from Multipotent CD15+ Cancer Stem Cells in Patched-1–Deficient Mouse Medulloblastoma
Authors: Ward Ryan J. , Lee Lilian , Graham Kevin , Satkunendran Thevagi , Yoshikawa Koichi , Ling Erick , Harper Lauren , Austin Ryan , Nieuwenhuis Erica , Clarke Ian D. , Hui Chi-chung , Dirks Peter B.
Published: March 2024

Abstract
Subpopulations of tumorigenic cells have been identified in many human tumors, although these cells may not be very rare in some types of cancer. Here, we report that medulloblastomas arising from Patched-1–deficient mice contain a subpopulation of cells that show a neural precursor phenotype, clonogenic and multilineage differentiation capacity, activated Hedgehog signaling, wild-type Patched-1 expression, and the ability to initiate tumors following allogeneic orthotopic transplantation. The normal neural stem cell surface antigen CD15 enriches for the in vitro proliferative and in vivo tumorigenic potential from uncultured medulloblastomas, supporting the existence of a cancer stem cell hierarchy in this clinically relevant mouse model of cancer. [Cancer Res 2009;69(11):4682–90]
Data from Persistence of High-Grade Cervical Dysplasia and Cervical Cancer Requires the Continuous Expression of the Human Papillomavirus Type 16 E7 Oncogene
Authors: Jabbar Sean F. , Abrams Linda , Glick Adam , Lambert Paul F.
Published: March 2024

Abstract
Several mucosotropic human papillomaviruses (HPV), including HPV type 16 (HPV-16), are etiologic agents of a subset of anogenital cancers and head and neck squamous cell carcinomas. In mice, HPV-16 E7 is the most potent of the papillomaviral oncogenes in the development of cervical disease. Furthermore, interfering specifically with the expression of E7 in HPV-positive cell lines derived from human cervical cancers inhibits their ability to proliferate, indicating that the expression of E7 is important in maintaining the transformed phenotype in vitro. To assess the temporal role of E7 in maintaining HPV-associated tumors and precancerous lesions in vivo, we generated Bi-L E7 transgenic mice that harbor a tetracycline-inducible transgene that expresses both HPV-16 E7 and firefly luciferase. When we crossed Bi-L E7 mice to a K5-tTA transgene-inducing line of mice, which expresses a tetracycline-responsive transactivator selectively in the stratified squamous epithelia, the resulting Bi-L E7/K5-tTA bitransgenic mice expressed E7 and luciferase in the skin and cervical epithelium, and doxycycline repressed this expression. Bitransgenic mice displayed several overt and acute epithelial phenotypes previously shown to be associated with the expression of E7, and these phenotypes were reversed on treatment with doxycycline. Repressing the expression of E7 caused the regression of high-grade cervical dysplasia and established cervical tumors, indicating that they depend on the continuous expression of E7 for their persistence. These results suggest that E7 is a relevant target not only for anticancer therapy but also for the treatment of HPV-positive dysplastic cervical lesions. [Cancer Res 2009;69(10):4407–14]
Data from The Vascular Endothelial Growth Factor Receptor Inhibitor PTK787/ZK222584 Inhibits Aromatase
Authors: Banerjee Susana , Zvelebil Marketa , Furet Pascal , Mueller-Vieira Ursula , Evans Dean B. , Dowsett Mitch , Martin Lesley-Ann
Published: March 2024

Abstract
Endocrine therapy is well established for the treatment of breast cancer, and antiangiogenic agents are showing considerable promise. Targeting the vascular endothelial growth factor (VEGF) and estrogen receptor (ER) signaling pathways concomitantly may provide enhanced therapeutic benefit in ER-positive breast cancer. Therefore, the effects of the VEGF receptor (VEGFR) tyrosine kinase inhibitor PTK787/ZK222584 (PTK/ZK) were investigated using human breast cancer cell lines engineered to express aromatase. As expected in this system, estrogen (E2) or androstenedione induced a proliferative response and increased ER-mediated transcription in ER-positive cell lines expressing aromatase. However, surprisingly, in the presence of androstenedione, PTK/ZK suppressed both the androstenedione-stimulated proliferation and ER-mediated transcription. PTK/ZK alone and in the presence of E2 had no observable effect on proliferation or ER-mediated transcription. These effects result from PTK/ZK having previously unrecognized antiaromatase activity and PTK/ZK being a competitive aromatase inhibitor. Computer-assisted molecular modeling showed that PTK/ZK could potentially bind directly to aromatase. The demonstration that PTK/ZK inhibits aromatase and VEGFR indicates that agents cross-inhibiting two important classes of targets in breast cancer could be developed. [Cancer Res 2009;69(11):4716–23]
Data from A Susceptibility Locus for Papillary Thyroid Carcinoma on Chromosome 8q24
Authors: He Huiling , Nagy Rebecca , Liyanarachchi Sandya , Jiao Hong , Li Wei , Suster Saul , Kere Juha , de la Chapelle Albert
Published: March 2024

Abstract
Papillary thyroid carcinoma (PTC) displays higher heritability than most other cancers. To search for genes predisposing to PTC, we performed a genome-wide linkage analysis in a large family with PTC and melanoma. Among several peaks the highest was at 8q24, with a maximum nonparametric linkage (NPL) score of 7.03. Linkage analysis was then broadened to comprise 25 additional PTC families that produced a maximum NPL score of 3.2, P = 0.007 at the 8q24 locus. Fine mapping with microsatellite markers was compatible with linkage to the 8q24 locus in 10 of the 26 families. In the large family, a ∼320 Kb haplotype was shared by individuals with PTC, melanoma, or benign thyroid disease, but not by unaffected individuals. A 12 Kb haplotype of 8 SNP markers within the larger haplotype was shared by 9 of the 10 families in which the 8q24 locus was compatible with linkage. The shared haplotype is located within 2 known overlapping protein-coding genes, thyroglobulin (TG) and Src-like adaptor (SLA). Resequencing of the coding and control regions of TG and SLA did not disclose putative mutations in PTC patients. Embedded in the TG-SLA region are three likely noncoding RNA genes, one of which (AK023948) harbors the 8-SNP haplotype. Resequencing of AK023948 and one of the other RNA genes did not reveal candidate mutations. Gene expression analysis indicated that AK023948 is significantly down-regulated in most PTC tumors. The putative noncoding RNA gene AK023948 is a candidate suseptibility gene for PTC. [Cancer Res 2009;69(2):625–31]
Data from Human Schwannomas Express Activated Platelet-Derived Growth Factor Receptors and c-kit and Are Growth Inhibited by Gleevec (Imatinib Mesylate)
Authors: Mukherjee Joydeep , Kamnasaran Deepak , Balasubramaniam Anand , Radovanovic Ivan , Zadeh Gelareh , Kiehl Tim-Rasmus , Guha Abhijit
Published: March 2024

Abstract
Schwannomas, although benign, can be fatal or give rise to significant morbidity due to an unpredictable growth rate. They can reoccur after surgery or radiation, current treatments each with significant inherent risks. These risks are further amplified in neurofibromatosis type 2 (NF2), a germ line predisposition syndrome characterized by multiple schwannomas, underlying the need for biological targeted therapies. Gleevec (STI571, imatinib mesylate), in addition to the bcr-abl oncogene in chronic myelogenous leukemia, inhibits c-kit and platelet-derived growth factor receptor (PDGFR) signaling, thereby expanding its use to several malignant and benign human diseases. In the present study, we show that human sporadic and NF2-associated schwannomas have increased expression along with activation of PDGFR-α, PDGFR-β, and c-kit receptors, compared with normal or traumatic nerve. Using the human NF2-null HEI-193 schwannoma cell line, Gleevec inhibited schwannoma viability, proliferation, and anchorage-independent growth, as well as induced apoptosis in a dose-dependent manner (IC50 5–10 μmol/L). These antitumorigenic effects were correlated to inhibition of PDGFR-α, PDGFR-β, and c-kit activation/phosphorylation and major downstream signaling pathways. Lack of robust xenograft or transgenic models of schwannomas prevents extension of these studies in vivo. However, the established long track record and tolerable toxicity of Gleevec already in clinical use and our preclinical data lead us to propose that Gleevec should be evaluated in human schwannomas with shown progressive growth. [Cancer Res 2009;69(12):5099–107]
Data from Role of Cell Cycle in Epidermal Growth Factor Receptor Inhibitor-Mediated Radiosensitization
Authors: Ahsan Aarif , Hiniker Susan M. , Davis Mary A. , Lawrence Theodore S. , Nyati Mukesh K.
Published: March 2024

Abstract
Epidermal growth factor receptor (EGFR) inhibitors are increasingly used in combination with radiotherapy in the treatment of various EGFR-overexpressing cancers. However, little is known about the effects of cell cycle status on EGFR inhibitor-mediated radiosensitization. Using EGFR-overexpressing A431 and UMSCC-1 cells in culture, we found that radiation activated the EGFR and extracellular signal-regulated kinase pathways in quiescent cells, leading to progression of cells from G1 to S, but this activation and progression did not occur in proliferating cells. Inhibition of this activation blocked S-phase progression and protected quiescent cells from radiation-induced death. To determine if these effects were caused by EGFR expression, we transfected Chinese hamster ovary (CHO) cells, which lack EGFR expression, with EGFR expression vector. EGFR expressed in CHO cells also became activated in quiescent cells but not in proliferating cells after irradiation. Moreover, quiescent cells expressing EGFR underwent increased radiation-induced clonogenic death compared with both proliferating CHO cells expressing EGFR and quiescent wild-type CHO cells. Our data show that radiation-induced enhancement of cell death in quiescent cells involves activation of the EGFR and extracellular signal-regulated kinase pathways. Furthermore, they suggest that EGFR inhibitors may protect quiescent tumor cells, whereas radiosensitization of proliferating cells may be caused by downstream effects such as cell cycle redistribution. These findings emphasize the need for careful scheduling of treatment with the combination of EGFR inhibitors and radiation and suggest that EGFR inhibitors might best be given after radiation in order to optimize clinical outcome. [Cancer Res 2009;69(12):5108–14]
Data from Pulmonary Vascular Destabilization in the Premetastatic Phase Facilitates Lung Metastasis
Authors: Huang Yujie , Song Nan , Ding Yanping , Yuan Shaopeng , Li Xuhui , Cai Hongchen , Shi Hubing , Luo Yongzhang
Published: March 2024

Abstract
Before metastasis, certain organs have already been influenced by primary tumors. However, the exact alterations and regulatory mechanisms of the premetastatic organs remain poorly understood. Here, we report that, in the premetastatic stage, angiopoietin 2 (Angpt2), matrix metalloproteinase (MMP) 3, and MMP10 are up-regulated in the lung by primary B16/F10 tumor, which leads to the increased permeability of pulmonary vasculatures and extravasation of circulating tumor cells. Subsequent studies show that Angpt2, MMP3, and MMP10 have a synergistic effect on disrupting vascular integrity in both in vitro and in vivo models. Lentivirus-based in vivo RNA interference of Angpt2, MMP3, and MMP10 attenuates the pulmonary vascular permeability and suppresses the infiltration of myeloid cells in the premetastatic lung. Moreover, knocking down these factors significantly inhibits the spontaneous lung metastasis in the model by orthotopic implantation of MDA-MB-231-Luc-D3H1 cells in nude mice. Further investigations reveal that the malignancy of tumor cells is positively correlated with their capabilities to induce the expression of Angpt2, MMP3, and MMP10. Luciferase reporter assay and chromatin immunoprecipitation assay also suggest that transforming growth factor-β1 and tumor necrosis factor-α signaling are involved in the regulation of these premetastatic factors. Our study shows that pulmonary vascular destabilization in the premetastatic phase promotes the extravasation of tumor cells and facilitates lung metastasis, which may provide potential targets for clinical prevention of metastasis. [Cancer Res 2009;69(19):7529–37]
Data from miR-21: An Androgen Receptor–Regulated MicroRNA that Promotes Hormone-Dependent and Hormone-Independent Prostate Cancer Growth
Authors: Ribas Judit , Ni Xiaohua , Haffner Michael , Wentzel Erik A. , Salmasi Amirali Hassanzadeh , Chowdhury Wasim H. , Kudrolli Tarana A. , Yegnasubramanian Srinivasan , Luo Jun , Rodriguez Ron , Mendell Joshua T. , Lupold Shawn E.
Published: March 2024

Abstract
Androgen receptor (AR)–mediated oncogenic pathways have not been fully elucidated. In this study, we used high-throughput microarray analysis on two AR-positive prostate cancer (CaP) cell lines to identify 16 AR-responsive microRNAs (miRNA). We focused on miR-21 because of its previously reported oncogenic activity in other cancers. We show androgen-induced AR binding to the defined miR-21 promoter, miPPR-21, suggesting direct transcriptional regulation. Inhibition of miR-21 diminished androgen-induced CaP cell proliferation, providing new evidence that miRNAs can contribute to androgen-driven cell growth. Elevated expression of miR-21 enhanced CaP tumor growth in vivo and, surprisingly, was sufficient for androgen-dependent tumors to overcome castration-mediated growth arrest. Thus, elevated miR-21 expression alone is sufficient to impart castration resistance. Moreover, quantitative reverse transcription-PCR analysis revealed elevated miR-21 expression in CaP when compared with adjacent normal tissue. These results suggest that miR-21 may contribute to CaP pathogenesis. [Cancer Res 2009;69(18):7165–9]
Data from CMTM3, Located at the Critical Tumor Suppressor Locus 16q22.1, Is Silenced by CpG Methylation in Carcinomas and Inhibits Tumor Cell Growth through Inducing Apoptosis
Authors: Wang Yu , Li Jisheng , Cui Yan , Li Ting , Ng Ka Man , Geng Hua , Li Henan , Shu Xing-sheng , Li Hongyu , Liu Wei , Luo Bing , Zhang Qian , Mok Tony Shu Kam , Zheng Wei , Qiu Xiaoyan , Srivastava Gopesh , Yu Jun , Sung Joseph J.Y. , Chan Anthony T.C. , Ma Dalong , Tao Qian , Han Wenling
Published: March 2024

Abstract
Closely located at the tumor suppressor locus 16q22.1, CKLF-like MARVEL transmembrane domain-containing member 3 and 4 (CMTM3 and CMTM4) encode two CMTM family proteins, which link chemokines and the transmembrane-4 superfamily. In contrast to the broad expression of both CMTM3 and CMTM4 in normal human adult tissues, only CMTM3 is silenced or down-regulated in common carcinoma (gastric, breast, nasopharyngeal, esophageal, and colon) cell lines and primary tumors. CMTM3 methylation was not detected in normal epithelial cell lines and tissues, with weak methylation present in only 5 of 35 (14%) gastric cancer adjacent normal tissues. Furthermore, immunohistochemistry showed that CMTM3 protein was absent in 12 of 35 (34%) gastric and 1 of 2 colorectal tumors, which was well correlated with its methylation status. The silencing of CMTM3 is due to aberrant promoter CpG methylation that could be reversed by pharmacologic demethylation. Ectopic expression of CMTM3 strongly suppressed the colony formation of carcinoma cell lines. In addition, CMTM3 inhibited tumor cell growth and induced apoptosis with caspase-3 activation. Thus, CMTM3 exerts tumor-suppressive functions in tumor cells, with frequent epigenetic inactivation by promoter CpG methylation in common carcinomas. [Cancer Res 2009;69(12):5194–201]
Data from Inhibitors of Deacetylases Suppress Oncogenic KIT Signaling, Acetylate HSP90, and Induce Apoptosis in Gastrointestinal Stromal Tumors
Authors: Mühlenberg Thomas , Zhang Yixiang , Wagner Andrew J. , Grabellus Florian , Bradner James , Taeger Georg , Lang Hauke , Taguchi Takahiro , Schuler Martin , Fletcher Jonathan A. , Bauer Sebastian
Published: March 2024

Abstract
Gastrointestinal stromal tumors (GIST) are characterized by activating mutations of KIT or platelet-derived growth factor receptor A (PDGFRA), and treatment with the tyrosine kinase inhibitor imatinib yields responses in the majority of patients. However, most patients develop secondary resistance, which is associated with a dismal prognosis. Histone deacetylase inhibitors (HDACI) have been shown to enhance imatinib activity in imatinib-resistant chronic myelogenous leukemia. Against this background, we explored whether HDACI might provide an alternative therapeutic strategy to KIT/PDGFRA kinase inhibitors in GIST. Inhibition of cell proliferation by HDACI was seen in KIT-positive but not in KIT-negative GIST cell lines, suggesting that HDACI activity is mainly conferred by targeting oncogenic KIT. KIT activity, expression, and activation of downstream pathways were strongly inhibited by several HDACI (SAHA, LBH589, VPA, trichostatin A, and NaButyrate). SAHA and LBH589 induced apoptosis in KIT-positive GIST, and strong synergism with imatinib was observed at low concentrations of SAHA and LBH589. Mechanistically, treatment with HDACI reduced KIT mRNA transcript levels and led to strong acetylation of HSP90, interfering with its activity as KIT chaperone. These results provide preclinical evidence for a disease-specific effect of HDACI in KIT-positive GIST, which could translate into therapeutic activity. [Cancer Res 2009;69(17):6941–50]
Data from Identification of PDE4D as a Proliferation Promoting Factor in Prostate Cancer Using a Sleeping Beauty Transposon-Based Somatic Mutagenesis Screen
Authors: Rahrmann Eric P. , Collier Lara S. , Knutson Todd P. , Doyal Meghan E. , Kuslak Sheri L. , Green Laura E. , Malinowski Rita L. , Roethe Laura , Akagi Keiko , Waknitz Michelle , Huang Wei , Largaespada David A. , Marker Paul C.
Published: March 2024

Abstract
Retroviral and transposon-based mutagenesis screens in mice have been useful for identifying candidate cancer genes for some tumor types. However, many of the organs that exhibit the highest cancer rates in humans, including the prostate, have not previously been amenable to these approaches. This study shows for the first time that the Sleeping Beauty transposon system can be used to identify candidate prostate cancer genes in mice. Somatic mobilization of a mutagenic transposon resulted in focal epithelial proliferation and hyperplasia in the prostate. Efficient methods were established to identify transposon insertion sites in these lesions, and analysis of transposon insertions identified candidate prostate cancer genes at common insertion sites, including Pde4d. PDE4D was also overexpressed in human prostate cancer patient samples and cell lines, and changes in PDE4D mRNA isoform expression were observed in human prostate cancers. Furthermore, knockdown of PDE4D reduced the growth and migration of prostate cancer cells in vitro, and knockdown of PDE4D reduced the growth and proliferation rate of prostate cancer xenografts in vivo. These data indicate that PDE4D functions as a proliferation promoting factor in prostate cancer, and the Sleeping Beauty transposon system is a useful tool for identifying candidate prostate cancer genes. [Cancer Res 2009;69(10):4388–97]
Data from 3,3′-Diindolylmethane Enhances Chemosensitivity of Multiple Chemotherapeutic Agents in Pancreatic Cancer
Authors: Banerjee Sanjeev , Wang Zhiwei , Kong Dejuan , Sarkar Fazlul H.
Published: March 2024

Abstract
Clinical management of pancreatic cancer is a major problem, which is in part due to both de novo and acquired resistance to conventional therapeutics. Here, we present in vitro and in vivo preclinical evidence in support of chemosensitization of pancreatic cancer cells by 3,3-diindolylmethane (DIM), a natural compound that can be easily obtained by consuming cruciferous vegetables. DIM pretreatment of pancreatic cancer cells led to a significantly increased apoptosis (P < 0.01) with suboptimal concentrations of chemotherapeutic agents (cisplatin, gemcitabine, and oxaliplatin) compared with monotherapy. It is known that resistance to chemotherapy in pancreatic cancer is associated with constitutively activated nuclear factor-κB (NF-κB), which becomes further activated by chemotherapeutic drugs. Our data provide mechanistic evidence for the first time showing that DIM potentiates the killing of pancreatic cancer cells by down-regulation of constitutive as well as drug-induced activation of NF-κB and its downstream genes (Bcl-xL, XIAP, cIAP, and survivin). Most importantly, using an orthotopic animal model, we found reduction in tumor size (P < 0.001) when DIM was given in combination with oxaliplatin compared with monotherapy. This was accompanied by loss of phospho-p65 and down-regulation of NF-κB activity and its downstream genes (Bcl-xL, survivin, and XIAP), which correlated with reduced cell proliferation (as assessed by Ki-67 immunostaining of tumor specimens) and evidence of apoptosis [as assessed by poly(ADP-ribose) polymease cleavage and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling staining]. These results provide strong in vivo evidence in support of our hypothesis that DIM could abrogate chemotherapeutic drug (cisplatin, gemcitabine, and/or oxaliplatin)–induced activation of NF-κB, resulting in the chemosensitization of pancreatic tumors to conventional therapeutics. [Cancer Res 2009;69(13):5592–600]
Data from Polycomb CBX7 Promotes Initiation of Heritable Repression of Genes Frequently Silenced with Cancer-Specific DNA Hypermethylation
Authors: Mohammad Helai P. , Cai Yi , McGarvey Kelly M. , Easwaran Hariharan , Van Neste Leander , Ohm Joyce E. , O'Hagan Heather M. , Baylin Stephen B.
Published: March 2024

Abstract
Epigenetic silencing of genes in association with aberrant promoter DNA hypermethylation has emerged as a significant mechanism in the development of human cancers. Such genes are also often targets of the polycomb group repressive complexes in embryonic cells. The polycomb repressive complex 2 (PRC2) has been best studied in this regard. We now examine a link between PRC1 and cancer-specific gene silencing. Here, we show a novel and direct association between a constituent of the PRC1 complex, CBX7, with gene repression and promoter DNA hypermethylation of genes frequently silenced in cancer. CBX7 is able to complex with DNA methyltransferase (DNMT) enzymes, leading us to explore a role for CBX7 in maintenance and initiation of gene silencing. Knockdown of CBX7 was unable to relieve suppression of deeply silenced genes in cancer cells; however, in embryonal carcinoma (EC) cells, CBX7 can initiate stable repression of genes that are frequently silenced in adult cancers. Furthermore, we are able to observe assembly of DNMTs at CBX7 target gene promoters. Sustained expression of CBX7 in EC cells confers a growth advantage and resistance to retinoic acid–induced differentiation. In this setting, especially, there is increased promoter DNA hypermethylation for many genes by analysis of specific genes, as well as through epigenomic studies. Our results allow us to propose a potential mechanism through assembly of novel repressive complexes, by which the polycomb component of PRC1 can promote the initiation of epigenetic changes involving abnormal DNA hypermethylation of genes frequently silenced in adult cancers. [Cancer Res 2009;69(15):6322–30]
Data from Overexpression of RhoA Induces Preneoplastic Transformation of Primary Mammary Epithelial Cells
Authors: Zhao Xiangshan , Lu Lin , Pokhriyal Nidhi , Ma Hui , Duan Lei , Lin Simon , Jafari Nadereh , Band Hamid , Band Vimla
Published: March 2024

Abstract
Rho family small GTPases serve as molecular switches in the regulation of diverse cellular functions, including actin cytoskeleton remodeling, cell migration, gene transcription, and cell proliferation. Importantly, Rho overexpression is frequently seen in many carcinomas. However, published studies have almost invariably used immortal or tumorigenic cell lines to study Rho GTPase functions and there are no studies on the potential of Rho small GTPase to overcome senescence checkpoints and induce preneoplastic transformation of human mammary epithelial cells (hMEC). We show here that ectopic expression of wild-type (WT) RhoA as well as a constitutively active RhoA mutant (G14V) in two independent primary hMEC strains led to their immortalization and preneoplastic transformation. These cells have continued to grow over 300 population doublings (PD) with no signs of senescence, whereas cells expressing the vector or dominant-negative RhoA mutant (T19N) senesced after 20 PDs. Significantly, RhoA-T37A mutant, known to be incapable of interacting with many well-known Rho effectors including Rho kinase, PKN, mDia1, and mDia2, was also capable of immortalizing hMECs. Notably, similar to parental normal cells, Rho-immortalized cells have WT p53 and intact G1 cell cycle arrest on Adriamycin treatment. Rho-immortalized cells were anchorage dependent and were unable to form tumors when implanted in nude mice. Lastly, microarray expression profiling of Rho-immortalized versus parental cells showed altered expression of several genes previously implicated in immortalization and breast cancer progression. Taken together, these results show that RhoA can induce the preneoplastic transformation of hMECs by altering multiple pathways linked to cellular transformation and breast cancer. [Cancer Res 2009;69(2):483–91]