bluuebunny/crossref_metadata_2025 huggingface dataset:
Data from The HER4/4ICD Estrogen Receptor Coactivator and BH3-Only Protein Is an Effector of Tamoxifen-Induced Apoptosis
Authors: Naresh Anjali , Thor Ann D. , Edgerton Susan M. , Torkko Kathleen C. , Kumar Rakesh , Jones Frank E.
Published: March 2024

Abstract
Greater than 40% of breast cancer patients treated with tamoxifen exhibit de novo or acquired tumor resistance. Recent clinical evidence indicates that loss of expression of HER4 is an independent marker for tamoxifen resistance. In direct corroboration with clinical observations, suppression of HER4 expression in the tamoxifen-sensitive MCF-7 and T47D breast tumor cell lines resulted in resistance to tamoxifen-induced apoptosis. Furthermore, HER4 expression was lost in three independent MCF-7 models of acquired tamoxifen resistance. The HER4 intracellular domain (4ICD) is an independently signaling nuclear protein that functions as a potent ERα coactivator. In addition, mitochondrial 4ICD functions as a proapoptotic BH3-only protein. Tamoxifen disrupts an estrogen-driven interaction between ERα and 4ICD while promoting mitochondrial accumulation of the 4ICD BH3-only protein. BCL-2 inhibition of tamoxifen-induced apoptosis and tamoxifen activation of BAK, independent of BAX, further supports a role for 4ICD during tamoxifen-induced apoptosis. Finally, reintroduction of HER4, but not HER4 with a mutated BH3 domain, restores tamoxifen sensitivity to tamoxifen-resistant TamR cells in a xenograft model. Clinically, breast cancer patients with tumor expression of nuclear 4ICD responded to tamoxifen therapy with no clinical failures reported after 14 years of follow-up, whereas 20% of patients lacking nuclear 4ICD expression succumbed to their disease within 10 years of diagnosis. Our identification of the HER4/4ICD BH3-only protein as a critical mediator of tamoxifen action provides a clinically important role for 4ICD in human cancer and reveals a potential tumor marker to predict patient response to tamoxifen therapy. [Cancer Res 2008;68(15):6387–95]
Data from Oncogene-Mediated Inhibition of Glycogen Synthase Kinase 3β Impairs Degradation of Prolactin Receptor
Authors: Plotnikov Alexander , Li Ying , Tran Thai H. , Tang Weigang , Palazzo Juan P. , Rui Hallgeir , Fuchs Serge Y.
Published: March 2024

Abstract
Prolactin receptors (PRLr) expressed in a majority of breast cancer are activated by prolactin and growth hormone. The PRLr is commonly stabilized in human breast cancer due to decreased phosphorylation of residue Ser349, which, when phosphorylated, recruits the βTrcp E3 ubiquitin ligase and facilitates PRLr degradation. Here, we show that constitutive oncogenic signaling downstream of ErbB2 and Ras stabilizes PRLr via inhibitory phosphorylation of glycogen synthase kinase-3β (GSK3β) on Ser9. Importantly, inactivation of GSK3β correlates with elevated levels of PRLr protein in clinical human breast cancer specimens. Additional studies using pharmacologic, biochemical, and genetic approaches reveal that GSK3β is a bona fide PRLr kinase that phosphorylates PRLr on Ser349 and is required for the recognition of PRLr by βTrcp, as well as for PRLr ubiquitination and degradation. [Cancer Res 2008;68(5):1354–61]
Data from 14-3-3ζ Down-regulates p53 in Mammary Epithelial Cells and Confers Luminal Filling
Authors: Danes Christopher G. , Wyszomierski Shannon L. , Lu Jing , Neal Christopher L. , Yang Wentao , Yu Dihua
Published: March 2024

Abstract
Recent progress in diagnostic tools allows many breast cancers to be detected at an early preinvasive stage. Thus, a better understanding of the molecular basis of early breast cancer progression is essential. Previously, we discovered that 14-3-3ζ is overexpressed in >40% of advanced breast cancers, and this overexpression predicts poor patient survival. Here, we examined at what stage of breast disease 14-3-3ζ overexpression occurs, and we found that increased expression of 14-3-3ζ begins at atypical ductal hyperplasia, an early stage of breast disease. To determine whether 14-3-3ζ overexpression is a decisive early event in breast cancer, we overexpressed 14-3-3ζ in MCF10A cells and examined its effect in a three-dimensional culture model. We discovered that 14-3-3ζ overexpression severely disrupted the acini architecture resulting in luminal filling. Proper lumen formation is a result of anoikis, apoptosis due to detachment from the basement membrane. We found that 14-3-3ζ overexpression conferred resistance to anoikis. Additionally, 14-3-3ζ overexpression in MCF10A cells and in mammary epithelial cells (MEC) from 14-3-3ζ transgenic mice reduced expression of p53, which is known to mediate anoikis. Mechanistically, 14-3-3ζ induced hyperactivation of the phosphoinositide 3-kinase/Akt pathway which led to phosphorylation and translocation of the MDM2 E3 ligase resulting in increased p53 degradation. Ectopic expression of p53 restored luminal apoptosis in 14-3-3ζ–overexpressing MCF10A acini in three-dimensional cultures. These data suggest that 14-3-3ζ overexpression is a critical event in early breast disease, and down-regulation of p53 is one of the mechanisms by which 14-3-3ζ alters MEC acini structure and increases the risk of breast cancer. [Cancer Res 2008;68(6):1760–7]
Data from Rational Design of Human DNA Ligase Inhibitors that Target Cellular DNA Replication and Repair
Authors: Chen Xi , Zhong Shijun , Zhu Xiao , Dziegielewska Barbara , Ellenberger Tom , Wilson Gerald M. , MacKerell Alexander D. , Tomkinson Alan E.
Published: March 2024

Abstract
Based on the crystal structure of human DNA ligase I complexed with nicked DNA, computer-aided drug design was used to identify compounds in a database of 1.5 million commercially available low molecular weight chemicals that were predicted to bind to a DNA-binding pocket within the DNA-binding domain of DNA ligase I, thereby inhibiting DNA joining. Ten of 192 candidates specifically inhibited purified human DNA ligase I. Notably, a subset of these compounds was also active against the other human DNA ligases. Three compounds that differed in their specificity for the three human DNA ligases were analyzed further. L82 inhibited DNA ligase I, L67 inhibited DNA ligases I and III, and L189 inhibited DNA ligases I, III, and IV in DNA joining assays with purified proteins and in cell extract assays of DNA replication, base excision repair, and nonhomologous end-joining. L67 and L189 are simple competitive inhibitors with respect to nicked DNA, whereas L82 is an uncompetitive inhibitor that stabilized complex formation between DNA ligase I and nicked DNA. In cell culture assays, L82 was cytostatic whereas L67 and L189 were cytotoxic. Concordant with their ability to inhibit DNA repair in vitro, subtoxic concentrations of L67 and L189 significantly increased the cytotoxicity of DNA-damaging agents. Interestingly, the ligase inhibitors specifically sensitized cancer cells to DNA damage. Thus, these novel human DNA ligase inhibitors will not only provide insights into the cellular function of these enzymes but also serve as lead compounds for the development of anticancer agents. [Cancer Res 2008;68(9):3169–77]
Data from AMP-Activated Protein Kinase Signaling Results in Cytoplasmic Sequestration of p27
Authors: Short John D. , Houston Kevin D. , Dere Ruhee , Cai Sheng-Li , Kim Jinhee , Johnson Charles L. , Broaddus Russell R. , Shen Jianjun , Miyamoto Susie , Tamanoi Fuyuhiko , Kwiatkowski David , Mills Gordon B. , Walker Cheryl Lyn
Published: March 2024

Abstract
Tuberin, the Tsc2 gene product, integrates the phosphatidylinositol 3-kinase/mitogen-activated protein kinase (mitogenic) and LKB1/AMP-activated protein kinase (AMPK; energy) signaling pathways, and previous independent studies have shown that loss of tuberin is associated with elevated AMPK signaling and altered p27 function. In Tsc2-null tumors and tumor-derived cells from Eker rats, we observed elevated AMPK signaling and concordant cytoplasmic mislocalization of p27. Cytoplasmic localization of p27 in Tsc2-null cells was reversible pharmacologically using inhibitors of the LKB1/AMPK pathway, and localization of p27 to the cytoplasm could be induced directly by activating AMPK physiologically (glucose deprivation) or genetically (constitutively active AMPK) in Tsc2-proficient cells. Furthermore, AMPK phosphorylated p27 in vitro on at least three sites including T170 near the nuclear localization signal, and T170 was shown to determine p27 localization in response to AMPK signaling. p27 functions in the nucleus to suppress cyclin-dependent kinase-2 (Cdk2) activity and has been reported to mediate an antiapoptotic function when localized to the cytoplasm. We found that cells with elevated AMPK signaling and cytoplasmic p27 localization exhibited elevated Cdk2 activity, which could be suppressed by inhibiting AMPK signaling. In addition, cells with elevated AMPK signaling and cytoplasmic p27 localization were resistant to apoptosis, which could be overcome by inhibition of AMPK signaling and relocalization of p27 to the nucleus. These data show that AMPK signaling determines the subcellular localization of p27, and identifies loss of integration of pathways controlling energy balance, the cell cycle, and apoptosis due to aberrant AMPK and p27 function as a feature of cells that have lost the Tsc2 tumor suppressor gene. [Cancer Res 2008;68(16):6496–506]
Data from MicroRNA Microarray Identifies Let-7i as a Novel Biomarker and Therapeutic Target in Human Epithelial Ovarian Cancer
Authors: Yang Nuo , Kaur Sippy , Volinia Stefano , Greshock Joel , Lassus Heini , Hasegawa Kosei , Liang Shun , Leminen Arto , Deng Shan , Smith Lori , Johnstone Cameron N. , Chen Xian-Ming , Liu Chang-Gong , Huang Qihong , Katsaros Dionyssios , Calin George Adrian , Weber Barbara L. , Bützow Ralf , Croce Carlo M. , Coukos George , Zhang Lin
Published: March 2024

Abstract
MicroRNAs (miRNA) are approximately 22-nucleotide noncoding RNAs that negatively regulate protein-coding gene expression in a sequence-specific manner via translational inhibition or mRNA degradation. Our recent studies showed that miRNAs exhibit genomic alterations at a high frequency and their expression is remarkably deregulated in ovarian cancer, strongly suggesting that miRNAs are involved in the initiation and progression of this disease. In the present study, we performed miRNA microarray to identify the miRNAs associated with chemotherapy response in ovarian cancer and found that let-7i expression was significantly reduced in chemotherapy-resistant patients (n = 69, P = 0.003). This result was further validated by stem-loop real-time reverse transcription-PCR (n = 62, P = 0.015). Both loss-of-function (by synthetic let-7i inhibitor) and gain-of-function (by retroviral overexpression of let-7i) studies showed that reduced let-7i expression significantly increased the resistance of ovarian and breast cancer cells to the chemotherapy drug, cis-platinum. Finally, using miRNA microarray, we found that decreased let-7i expression was significantly associated with the shorter progression-free survival of patients with late-stage ovarian cancer (n = 72, P = 0.042). This finding was further validated in the same sample set by stem-loop real-time reverse transcription-PCR (n = 62, P = 0.001) and in an independent sample set by in situ hybridization (n = 53, P = 0.049). Taken together, our results strongly suggest that let-7i might be used as a therapeutic target to modulate platinum-based chemotherapy and as a biomarker to predict chemotherapy response and survival in patients with ovarian cancer. [Cancer Res 2008;68(24):10307–14]
Data from Glucocorticoids Antagonize Estrogens by Glucocorticoid Receptor–Mediated Activation of Estrogen Sulfotransferase
Authors: Gong Haibiao , Jarzynka Michael J. , Cole Timothy J. , Lee Jung Hoon , Wada Taira , Zhang Bin , Gao Jie , Song Wen-Chao , DeFranco Donald B. , Cheng Shi-Yuan , Xie Wen
Published: March 2024

Abstract
Glucocorticoids and estrogens are two classes of steroid hormones that have essential but distinct physiologic functions. Estrogens also represent a risk factor for breast cancer. It has been suggested that glucocorticoids can attenuate estrogen responses, but the mechanism by which glucocorticoids inhibit estrogenic activity is unknown. In this study, we show that activation of glucocorticoid receptor (GR) by dexamethasone (DEX) induced the expression and activity of estrogen sulfotransferase (SULT1E1 or EST), an enzyme important for the metabolic deactivation of estrogens, because sulfonated estrogens fail to activate the estrogen receptor. Treatment with DEX lowered circulating estrogens, compromised uterine estrogen responses, and inhibited estrogen-dependent breast cancer growth in vitro and in a xenograft model. We further showed that the mouse and human SULT1E1 genes are transcriptional targets of GR and deletion of Sult1e1/Est in mice abolished the DEX effect on estrogen responses. These findings have revealed a novel nuclear receptor–mediated and metabolism-based mechanism of estrogen deprivation, which may have implications in therapeutic development for breast cancers. Because glucocorticoids and estrogens are widely prescribed drugs, our results also urge caution in avoiding glucocorticoid-estrogen interactions in patients. [Cancer Res 2008;68(18):7386–93]
Data from A Fluorescence In situ Hybridization Screen for E26 Transformation–Specific Aberrations: Identification of DDX5-ETV4 Fusion Protein in Prostate Cancer
Authors: Han Bo , Mehra Rohit , Dhanasekaran Saravana M. , Yu Jindan , Menon Anjana , Lonigro Robert J. , Wang Xiaosong , Gong Yusong , Wang Lei , Shankar Sunita , Laxman Bharathi , Shah Rajal B. , Varambally Sooryanarayana , Palanisamy Nallasivam , Tomlins Scott A. , Kumar-Sinha Chandan , Chinnaiyan Arul M.
Published: March 2024

Abstract
Recurrent gene fusions involving E26 transformation–specific (ETS) transcription factors ERG, ETV1, ETV4, or ETV5 have been identified in 40% to 70% of prostate cancers. Here, we used a comprehensive fluorescence in situ hybridization (FISH) split probe strategy interrogating all 27 ETS family members and their five known 5′ fusion partners in a cohort of 110 clinically localized prostate cancer patients. Gene rearrangements were only identified in ETS genes that were previously implicated in prostate cancer gene fusions including ERG, ETV1, and ETV4 (43%, 5%, and 5%, respectively), suggesting that a substantial fraction of prostate cancers (estimated at 30–60%) cannot be attributed to an ETS gene fusion. Among the known 5′ gene fusion partners, TMPRSS2 was rearranged in 47% of cases followed by SLC45A3, HNRPA2B1, and C15ORF21 in 2%, 1%, and 1% of cases, respectively. Based on this comprehensive FISH screen, we have made four noteworthy observations. First, by screening the entire ETS transcription factor family for rearrangements, we found that a large fraction of prostate cancers (44%) cannot be ascribed to an ETS gene fusion, an observation which will stimulate research into identifying recurrent non-ETS aberrations in prostate cancers. Second, we identified SLC45A3 as a novel 5′ fusion partner of ERG; previously, TMPRSS2 was the only described 5′ partner of ERG. Third, we identified two prostate-specific, androgen-induced genes, FLJ35294 and CANT1, as 5′ partners to ETV1 and ETV4. Fourth, we identified a ubiquitously expressed, androgen-insensitive gene, DDX5, fused in frame with ETV4, leading to the expression of a DDX5-ETV4 fusion protein. [Cancer Res 2008;68(18):7629–37]
Data from Synthesis and Anticancer Properties of Water-Soluble Zinc Ionophores
Authors: Magda Darren , Lecane Philip , Wang Zhong , Hu Weilin , Thiemann Patricia , Ma Xuan , Dranchak Patricia K. , Wang Xiaoming , Lynch Vincent , Wei Wenhao , Csokai Viktor , Hacia Joseph G. , Sessler Jonathan L.
Published: March 2024

Abstract
Several water-solubilized versions of the zinc ionophore 1-hydroxypyridine-2-thione (ZnHPT), synthesized as part of the present study, have been found both to increase the intracellular concentrations of free zinc and to produce an antiproliferative activity in exponential phase A549 human lung cancer cultures. Gene expression profiles of A549 cultures treated with one of these water-soluble zinc ionophores, PCI-5002, reveal the activation of stress response pathways under the control of metal-responsive transcription factor 1 (MTF-1), hypoxia-inducible transcription factor 1 (HIF-1), and heat shock transcription factors. Additional oxidative stress response and apoptotic pathways were activated in cultures grown in zinc-supplemented media. We also show that these water-soluble zinc ionophores can be given to mice at 100 μmol/kg (300 μmol/m2) with no observable toxicity and inhibit the growth of A549 lung and PC3 prostate cancer cells grown in xenograft models. Gene expression profiles of tumor specimens harvested from mice 4 h after treatment confirmed the in vivo activation of MTF-1–responsive genes. Overall, we propose that water-solubilized zinc ionophores represent a potential new class of anticancer agents. [Cancer Res 2008;68(13):5318–25]
Data from Low Levels of Tumor Necrosis Factor α Increase Tumor Growth by Inducing an Endothelial Phenotype of Monocytes Recruited to the Tumor Site
Authors: Li Bin , Vincent Alicia , Cates Justin , Brantley-Sieders Dana M. , Polk D. Brent , Young Pampee P.
Published: March 2024

Abstract
Microenvironmental cues instruct infiltrating tumor-associated myeloid cells to drive malignant progression. A subpopulation of tumor-associated myeloid cells coexpressing endothelial and myeloid markers, although rare in peripheral blood, are primarily associated with tumors where they enhance tumor growth and angiogenesis. These biphenotypic vascular leukocytes result from the endothelial differentiation of myeloid progenitors, a process regulated by tumor necrosis factor (TNF)α in vitro. An in vivo increase in tumor-derived TNFα expression promoted tumor growth and vascularity of mouse melanoma, lung cancer, and mammary tumors. Notably, tumor growth was accompanied by a significant increase in myeloid/endothelial biphenotypic populations. TNFα-associated tumor growth, vascularity, and generation of tumor vascular leukocytes in mouse melanoma tumors were dependent on intact host TNFα receptors. Importantly, TNFα-expressing tumors did not exhibit increased inflammation over control tumors, suggesting a unique action related to myeloid to endothelial differentiation. Our studies suggest that TNFα constitutes a tumor microenvironment signal that biases recruited monocytes toward a proangiogenic/provasculogenic myeloid/endothelial phenotype. [Cancer Res 2009;69(1):338–48]
Data from Glycogen Synthase Kinase-3 Inhibition Induces Glioma Cell Death through c-MYC, Nuclear Factor-κB, and Glucose Regulation
Authors: Kotliarova Svetlana , Pastorino Sandra , Kovell Lara C. , Kotliarov Yuri , Song Hua , Zhang Wei , Bailey Rolanda , Maric Dragan , Zenklusen Jean Claude , Lee Jeongwu , Fine Howard A.
Published: March 2024

Abstract
Glycogen synthase kinase 3 (GSK3), a serine/threonine kinase, is involved in diverse cellular processes ranging from nutrient and energy homeostasis to proliferation and apoptosis. Its role in glioblastoma multiforme has yet to be elucidated. We identified GSK3 as a regulator of glioblastoma multiforme cell survival using microarray analysis and small-molecule and genetic inhibitors of GSK3 activity. Various molecular and genetic approaches were then used to dissect out the molecular mechanisms responsible for GSK3 inhibition–induced cytotoxicity. We show that multiple small molecular inhibitors of GSK3 activity and genetic down-regulation of GSK3α/β significantly inhibit glioma cell survival and clonogenicity. The potency of the cytotoxic effects is directly correlated with decreased enzyme activity–activating phosphorylation of GSK3α/β Y276/Y216 and with increased enzyme activity inhibitory phosphorylation of GSK3α S21. Inhibition of GSK3 activity results in c-MYC activation, leading to the induction of Bax, Bim, DR4/DR5, and tumor necrosis factor-related apoptosis-inducing ligand expression and subsequent cytotoxicity. Additionally, down-regulation of GSK3 activity results in alteration of intracellular glucose metabolism resulting in dissociation of hexokinase II from the outer mitochondrial membrane with subsequent mitochondrial destabilization. Finally, inhibition of GSK3 activity causes a dramatic decrease in intracellular nuclear factor-κB activity. Inhibition of GSK3 activity results in c-MYC–dependent glioma cell death through multiple mechanisms, all of which converge on the apoptotic pathways. GSK3 may therefore be an important therapeutic target for gliomas. Future studies will further define the optimal combinations of GSK3 inhibitors and cytotoxic agents for use in gliomas and other cancers. [Cancer Res 2008;68(16):6643–51]
Data from The Thioredoxin System Mediates Redox-Induced Cell Death in Human Colon Cancer Cells: Implications for the Mechanism of Action of Anticancer Agents
Authors: Sun Yu , Rigas Basil
Published: March 2024

Abstract
Anticancer agents act, at least in part, by inducing reactive oxygen and nitrogen species (RONS). We examined the redox effect on SW480 and HT-29 colon cancer cells of four anticancer compounds, arsenic trioxide, phosphoaspirin, phosphosulindac, and nitric oxide–donating aspirin (NO-ASA). All compounds inhibited the growth of both cell lines (IC50, 10–90 μmol/L) and induced RONS detected by a general RONS molecular probe. NO-ASA, which induced at least four individual RONS (NO, H2O2, superoxide anion, and peroxynitirte), induced apoptotic and necrotic cell death that was RONS-mediated (cell death paralleled RONS levels and was abrogated by N-acetyl cysteine but not by diphenylene iodonium, which displayed prooxidant activity and enhanced cell death). Nuclear factor-κB and mitogen-activated protein kinases were modulated by RONS. Thioredoxin-1 (Trx-1), an oxidoreductase involved in redox regulation, was heavily oxidized in response to RONS and mediated the growth inhibitory effect of the anticancer agents; knocking-down trx-1 expression by small interfering RNA abrogated cell death induced by them. These compounds also inhibited the activity of Trx reductase that reduces oxidized Trx-1, whereas the Trx reductase inhibitor aurothiomalate synergized with NO-ASA in the induction of cell death. Our findings indicate that the Trx system mediates to a large extent redox-induced cell death in response to anticancer agents. This mechanism of action may be shared by more anticancer agents and deserves further assessment as a candidate mechanism for the pharmacologic control of cancer. [Cancer Res 2008;68(20):8269–77]
Data from Ugene, a Newly Identified Protein That Is Commonly Overexpressed in Cancer and Binds Uracil DNA Glycosylase
Authors: Guo Chunguang , Zhang Xiaodong , Fink Stephen P. , Platzer Petra , Wilson Keith , Willson James K.V. , Wang Zhenghe , Markowitz Sanford D.
Published: March 2024

Abstract
Expression microarrays identified a novel transcript, designated as Ugene, whose expression is absent in normal colon and colon adenomas, but that is commonly induced in malignant colon cancers. These findings were validated by real-time PCR and Northern blot analysis in an independent panel of colon cancer cases. In addition, Ugene expression was found to be elevated in many other common cancer types, including breast, lung, uterus, and ovary. Immunofluorescence of V5-tagged Ugene revealed it to have a nuclear localization. In a pull-down assay, uracil DNA glycosylase 2 (UNG2), an important enzyme in the base excision repair (BER) pathway, was identified as a partner protein that binds to Ugene. Coimmunoprecipitation and Western blot analysis confirmed the binding between the endogenous Ugene and UNG2 proteins. Using deletion constructs, we find that Ugene binds to the first 25 amino acids of the UNG2 NH2 terminus. We suggest that Ugene induction in cancer may contribute to the cancer phenotype by interacting with the BER pathway. [Cancer Res 2008;68(15):6118–26]
Data from Steroid Receptor Coactivator-3/AIB1 Promotes Cell Migration and Invasiveness through Focal Adhesion Turnover and Matrix Metalloproteinase Expression
Authors: Yan Jun , Erdem Halime , Li Rile , Cai Yi , Ayala Gustavo , Ittmann Michael , Yu-Lee Li-yuan , Tsai Sophia Y. , Tsai Ming-Jer
Published: March 2024

Abstract
Steroid receptor coactivator-3 (SRC-3)/AIB1 is a member of the p160 nuclear receptor coactivator family involved in development and cell cycle progression. We previously showed that SRC-3/AIB1 is required for prostate cancer cell proliferation and survival. Here, we reported that the elevated SRC-3/AIB1 expression is significantly correlated with human prostate cancer seminal vesicle invasion and lymph node metastasis. Furthermore, SRC-3/AIB1 is associated with increased prostate cancer cell migration and invasion. SRC-3/AIB1 is required for focal adhesion turnover and focal adhesion kinase activation. In addition, SRC-3/AIB1 directly regulates transcription of matrix metalloproteinase (MMP)-2 and MMP-13 through its coactivation of AP-1 and PEA3. Taken together, these data suggest that SRC-3/AIB1 plays an essential role in prostate cancer cell invasion and metastasis. [Cancer Res 2008;68(13):5460–8]
Data from Functional Genetic Variations in Cytotoxic T-Lymphocyte Antigen 4 and Susceptibility to Multiple Types of Cancer
Authors: Sun Tong , Zhou Yifeng , Yang Ming , Hu Zhibin , Tan Wen , Han Xiaohong , Shi Yuankai , Yao Jiarui , Guo Yongli , Yu Dianke , Tian Tian , Zhou Xiaoyi , Shen Hongbing , Lin Dongxin
Published: March 2024

Abstract
Antitumor T lymphocytes play a pivotal role in immunosurveillance of malignancy. The CTL antigen 4 (CTLA-4) is a vital negative regulator of T-cell activation and proliferation. This study examined whether genetic polymorphisms in CTLA-4 are associated with cancer susceptibility. A two-stage investigation using haplotype-tagging single nucleotide polymorphism approach and multiple independent case-control analyses was performed to assess the association between CTLA-4 genotypes and cancer risk. Functional relevance of the polymorphisms was examined by biochemical assays. We found that the 49G>A polymorphism in the CTLA-4 leading sequence causing 17Ala to 17Thr amino acid substitution is associated with increased susceptibility to multiple cancers, including lung, breast, esophagus, and gastric cardia cancers. Genotyping in 5,832 individuals with cancer and 5,831 control subjects in northern and southern Chinese populations showed that the CTLA-4 49AA genotype had an odds ratio of 1.72 (95% confidence interval, 1.50−2.10; P = 3.4 × 10−7) for developing cancer compared with the 49GG genotype. Biochemical analyses showed that CTLA-4−17Thr had higher capability to bind B7.1 and stronger inhibitory effect on T-cell activation compared with CTLA-4−17Ala. T cells carrying the 49AA genotype had significantly lower activation and proliferation rates compared with T cells carrying the 49GG genotype upon stimulation. These results are consistent with our hypothesis and indicate that genetic polymorphisms influencing T-cell activation modify cancer susceptibility. [Cancer Res 2008;68(17):7025–34]
Data from Erlotinib Attenuates Homologous Recombinational Repair of Chromosomal Breaks in Human Breast Cancer Cells
Authors: Li Liping , Wang Hong , Yang Eddy S. , Arteaga Carlos L. , Xia Fen
Published: March 2024

Abstract
The epidermal growth factor receptor (EGFR) family has been implicated in several cancers, including breast, and its members have become the target of novel cancer therapies. In this report, we show a novel link between erlotinib, a potent EGFR inhibitor, DNA damage, and homology-directed recombinational repair (HDR) in human breast cancer cells. Erlotinib suppresses HDR. This is not secondary to erlotinib-mediated changes in cell cycle and is associated with increased γ-H2AX foci, which is an in situ marker of chromosomal double-strand breaks. Both Rad51 and BRCA1 are essential components of the HDR machinery. Consistent with decreased HDR in erlotinib-treated cells, erlotinib also attenuates DNA damage-induced Rad51 foci and results in cytoplasmic retention of BRCA1. As BRCA1 is a shuttling protein and its nuclear function of promoting HDR is controlled by its subcellular localization, we further show that targeted translocation of BRCA1 to the cytoplasm enhances erlotinib sensitivity. These findings suggest a novel mechanism of action of erlotinib through its effects on the BRCA1/HDR pathway. Furthermore, BRCA1/HDR status may be an innovative avenue to enhance the sensitivity of cancer cells to erlotinib. [Cancer Res 2008;68(22):9141–6]
Data from Repression of 15-Hydroxyprostaglandin Dehydrogenase Involves Histone Deacetylase 2 and Snail in Colorectal Cancer
Authors: Backlund Michael G. , Mann Jason R. , Holla Vijaykumar R. , Shi Qiong , Daikoku Takikoku , Dey Sudhansu K. , DuBois Raymond N.
Published: March 2024

Abstract
Prostaglandin E2 (PGE2) promotes cancer progression by modulating proliferation, apoptosis, angiogenesis, and the immune response. Enzymatic degradation of PGE2 involves the NAD+-dependent 15-hydroxyprostaglandin dehydrogenase (15-PGDH). Recent reports have shown a marked diminution of 15-PGDH expression in colorectal carcinomas (CRC). We report here that treatment of CRC cells with histone deacetylase (HDAC) inhibitors, including sodium butyrate and valproic acid, induces 15-PGDH expression. Additionally, we show that pretreatment of CRC cells with HDAC inhibitors can block epidermal growth factor–mediated or Snail-mediated transcriptional repression of 15-PGDH. We show an interaction between Snail and HDAC2 and the binding of HDAC2 to the 15-PGDH promoter. In vivo, we observe increased Hdac2 expression in Apc-deficient mouse adenomas, which inversely correlated with loss of 15-Pgdh expression. Finally, in human colon cancers, elevated HDAC expression correlated with down-regulation of 15-PGDH. These data suggest that class I HDACs, specifically HDAC2, and the transcriptional repressor Snail play a central role in the suppression of 15-PGDH expression. These results also provide a cyclooxygenase-2–independent mechanism to explain increased PGE2 levels that contribute to progression of CRC. [Cancer Res 2008;68(22):9331–7]
Data from One-Hit Effects in Cancer: Altered Proteome of Morphologically Normal Colon Crypts in Familial Adenomatous Polyposis
Authors: Yeung Anthony T. , Patel Bhavinkumar B. , Li Xin-Ming , Seeholzer Steven H. , Coudry Renata A. , Cooper Harry S. , Bellacosa Alfonso , Boman Bruce M. , Zhang Tao , Litwin Samuel , Ross Eric A. , Conrad Peggy , Crowell James A. , Kopelovich Levy , Knudson Alfred
Published: March 2024

Abstract
We studied patients with Familial Adenomatous Polyposis (FAP) because they are virtually certain to develop colon cancer, and because much is known about the causative APC gene. We hypothesized that the inherited heterozygous mutation itself leads to changes in the proteome of morphologically normal crypts and the proteins that changed may represent targets for preventive and therapeutic agents. We determined the differential protein expression of morphologically normal colon crypts of FAP patients versus those of individuals without the mutation, using two-dimensional gel electrophoresis, mass spectrometry, and validation by two-dimensional gel Western blotting. Approximately 13% of 1,695 identified proteins were abnormally expressed in the morphologically normal crypts of APC mutation carriers, indicating that a colon crypt cell under the one-hit state is already abnormal. Many of the expression changes affect pathways consistent with the function of the APC protein, including apoptosis, cell adhesion, cell motility, cytoskeletal organization and biogenesis, mitosis, transcription, and oxidative stress response. Thus, heterozygosity for a mutant APC tumor suppressor gene alters the proteome of normal-appearing crypt cells in a gene-specific manner, consistent with a detectable one-hit event. These changes may represent the earliest biomarkers of colorectal cancer development, potentially leading to the identification of molecular targets for cancer prevention. [Cancer Res 2008;68(18):7579–86]
Data from A Nanoparticle System Specifically Designed to Deliver Short Interfering RNA Inhibits Tumor Growth In vivo
Authors: Yagi Nobuhiro , Manabe Ichiro , Tottori Tsuneaki , Ishihara Atsushi , Ogata Fusa , Kim Jong Heon , Nishimura Satoshi , Fujiu Katsuhito , Oishi Yumiko , Itaka Keiji , Kato Yasuki , Yamauchi Masahiro , Nagai Ryozo
Published: March 2024

Abstract
Use of short interfering RNA (siRNA) is a promising new approach thought to have a strong potential to lead to rapid development of gene-oriented therapies. Here, we describe a newly developed, systemically injectable siRNA vehicle, the “wrapsome” (WS), which contains siRNA and a cationic lipofection complex in a core that is fully enveloped by a neutral lipid bilayer and hydrophilic polymers. WS protected siRNA from enzymatic digestion, providing a long half-life in the systemic circulation. Moreover, siRNA/WS leaked from blood vessels within tumors into the tumor tissue, where it accumulated and was subsequently transfected into the tumor cells. Because the transcription factor KLF5 is known to play a role in tumor angiogenesis, we designed KLF5-siRNA to test the antitumor activity of siRNA/WS. KLF5-siRNA/WS exhibited significant antitumor activity, although neither WS containing control scrambled-siRNA nor saline containing KLF5-siRNA affected tumor growth. KLF5-siRNA/WS inhibited Klf5 expression within tumors at both mRNA and protein levels, significantly reducing angiogenesis, and we detected no significant acute or long-term toxicity. Our findings support the idea that siRNA/WS can be used to knock down specific genes within tumors and thereby exert therapeutic effects against cancers. [Cancer Res 2009;69(16):6531–8]
Data from Polyps Wrap Mast Cells and Treg within Tumorigenic Tentacles
Authors: Colombo Mario P. , Piconese Silvia
Published: March 2024

Abstract
Gounaris and colleagues describe a previously unrecognized cross-talk between mast cells and Treg in colon adenomatous polyposis (Gounaris et al., Cancer Res 2009;69:5490–7). Adoptively transferred Treg suppress the focal mastocytosis that fosters tumor initiation and progression. In contrast, endogenous Treg, which abundantly infiltrate polyps, show proinflammatory activity under unknown microenvironmental cues that promote mast cell differentiation and expansion. Compartmentalized Treg plasticity seems to be a key factor in establishing the optimal milieu for cancer development in the intestines. Treg partnership with mast cells recapitulates the complexity of innate-adaptive networks characterizing gut inflammation and represents a novel target for cancer immunotherapy. [Cancer Res 2009;69(14):5619–22]
Data from Functional Restoration of BRCA2 Protein by Secondary BRCA2 Mutations in BRCA2-Mutated Ovarian Carcinoma
Authors: Sakai Wataru , Swisher Elizabeth M. , Jacquemont Céline , Chandramohan Kurapaty Venkatapoorna , Couch Fergus J. , Langdon Simon P. , Wurz Kaitlyn , Higgins Jake , Villegas Emily , Taniguchi Toshiyasu
Published: March 2024

Abstract
Acquired platinum resistance is a serious problem in the treatment of ovarian carcinomas. However, the mechanism of the drug resistance has not been elucidated. Here, we show functional significance of restoration of BRCA2 protein by secondary BRCA2 mutations in acquired drug resistance of BRCA2-mutated ovarian carcinoma. Three ovarian cancer cell lines (PEO1, PEO4, and PEO6) were derived from a BRCA2 mutation [5193C>G (Y1655X)] carrier with ovarian carcinoma with acquired cisplatin resistance and a secondary BRCA2 mutation [5193C>T (Y1655Y)] that canceled the inherited mutation. PEO1 was BRCA2 deficient and sensitive to cisplatin and a poly(ADP-ribose) polymerase inhibitor, AG14361, whereas PEO4 was resistant. PEO4 and PEO6, derived from ascites at the time of relapse with cisplatin resistance, had the secondary mutation and were BRCA2 proficient. In vitro cisplatin/AG14361 selection of PEO1 led to restoration of BRCA2 due to another secondary BRCA2 mutation. BRCA2 depletion sensitized BRCA2-restored PEO1 clones and PEO4 to cisplatin/AG14361. Thus, restoration of BRCA2 due to secondary BRCA2 mutation is involved in acquired drug resistance of BRCA2-mutated ovarian carcinoma. [Cancer Res 2009;69(16):6381–6]
Data from Dual Activity Lysophosphatidic Acid Receptor Pan-Antagonist/Autotaxin Inhibitor Reduces Breast Cancer Cell Migration In vitro and Causes Tumor Regression In vivo
Authors: Zhang Honglu , Xu Xiaoyu , Gajewiak Joanna , Tsukahara Ryoko , Fujiwara Yuko , Liu Jianxiong , Fells James I. , Perygin Donna , Parrill Abby L. , Tigyi Gabor , Prestwich Glenn D.
Published: March 2024

Abstract
Signal transduction modifiers that modulate the lysophosphatidic acid (LPA) pathway have potential as anticancer agents. Herein, we describe metabolically stabilized LPA analogues that reduce cell migration and invasion and cause regression of orthotopic breast tumors in vivo. Two diastereoisomeric α-bromophosphonates (BrP-LPA) were synthesized, and the pharmacology was determined for five LPA G protein–coupled receptors (GPCRs). The syn and anti diastereomers of BrP-LPA are pan-LPA GPCR antagonists and are also nanomolar inhibitors of the lysophospholipase D activity of autotaxin, the dominant biosynthetic source of LPA. Computational models correctly predicted the diastereoselectivity of antagonism for three GPCR isoforms. The anti isomer of BrP-LPA was more effective than syn isomer in reducing migration of MDA-MB-231 cells, and the anti isomer was superior in reducing invasion of these cells. Finally, orthotopic breast cancer xenografts were established in nude mice by injection of MB-231 cells in an in situ cross-linkable extracellular matrix. After 2 weeks, mice were treated with the BrP-LPA alone (10 mg/kg), Taxol alone (10 mg/kg), or Taxol followed by BrP-LPA. All treatments significantly reduced tumor burden, and BrP-LPA was superior to Taxol in reducing blood vessel density in tumors. Moreover, both the anti- and syn-BrP-LPA significantly reduced tumors at 3 mg/kg. [Cancer Res 2009;69(13):5441–9]
Data from Blockade of PAR1 Signaling with Cell-Penetrating Pepducins Inhibits Akt Survival Pathways in Breast Cancer Cells and Suppresses Tumor Survival and Metastasis
Authors: Yang Eric , Boire Adrienne , Agarwal Anika , Nguyen Nga , O'Callaghan Katie , Tu Powen , Kuliopulos Athan , Covic Lidija
Published: March 2024

Abstract
Protease-activated receptor 1 (PAR1) is a G protein–coupled receptor that is not expressed in normal breast epithelia but is up-regulated in invasive breast carcinomas. In the present study, we found that matrix metalloprotease-1 (MMP-1) robustly activates the PAR1-Akt survival pathway in breast carcinoma cells. This process is blocked by a cell-penetrating lipopeptide “pepducin,” P1pal-7, which is a potent inhibitor of cell viability in breast carcinoma cells expressing PAR1. Both a MMP-1 inhibitor and P1pal-7 significantly promote apoptosis in breast tumor xenografts and inhibit metastasis to the lungs by up to 88%. Dual therapy with P1pal-7 and Taxotere inhibits the growth of MDA-MB-231 xenografts by 95%. Consistently, biochemical analysis of xenograft tumors treated with P1pal-7 or MMP-1 inhibitor showed attenuated Akt activity. Ectopic expression of constitutively active Akt rescues breast cancer cells from the synergistic cytotoxicity of P1pal-7 and Taxotere, suggesting that Akt is a critical component of PAR1-dependent cancer cell viability. Together, these findings indicate that blockade of MMP1-PAR1 signaling may provide a benefit beyond treatment with Taxotere alone in advanced, metastatic breast cancer. [Cancer Res 2009;69(15):6223–31]
Data from Comparison of Primary Neuroblastoma Tumors and Derivative Early-Passage Cell Lines Using Genome-Wide Single Nucleotide Polymorphism Array Analysis
Authors: Volchenboum Samuel L. , Li Cheng , Li Shuli , Attiyeh Edward F. , Reynolds C. Patrick , Maris John M. , Look A. Thomas , George Rani E.
Published: March 2024

Abstract
Stromal contamination is one of the major confounding factors in the analysis of solid tumor samples by single nucleotide polymorphism (SNP) arrays. As we propose to use genome-wide SNP microarray analysis as a diagnostic platform for neuroblastoma, the sensitivity, specificity, and accuracy of these studies must be optimized. To investigate the effects of stromal contamination, we derived early-passage cell lines from nine primary tumors and compared their genomic signature with that of the primary tumors using 100K SNP arrays. The average concordance between tumor and cell line for raw loss of heterozygosity (LOH) calls was 96% (range, 91–99%) and for raw copy number alterations, 71% (range, 43–87%). In general, there were a larger number of LOH events identified in the cell lines compared with the matched tumor samples (mean increase, 3.2% ± 1.9%). We have developed an algorithm that shows that the presence of stroma contributes to under-reporting of LOH and copy number loss. Notable findings in this sample set were uniparental disomy of chromosome arms 11p, 1q, 14q, and 15q and a novel area of amplification on chromosome band 11p15. Our analysis shows that LOH was identified significantly more often in derived cell lines compared with the original tumor samples. Although these may in part be due to clonal selection during adaptation to tissue culture, our study indicates that stromal contamination may be a major contributing factor in underestimation of LOH and copy number loss events. [Cancer Res 2009;69(10):4143–9]
Data from Targeting Sphingosine Kinase 1 Inhibits Akt Signaling, Induces Apoptosis, and Suppresses Growth of Human Glioblastoma Cells and Xenografts
Authors: Kapitonov Dmitri , Allegood Jeremy C. , Mitchell Clint , Hait Nitai C. , Almenara Jorge A. , Adams Jeffrey K. , Zipkin Robert E. , Dent Paul , Kordula Tomasz , Milstien Sheldon , Spiegel Sarah
Published: March 2024

Abstract
Sphingosine-1-phosphate is a potent sphingolipid mediator of diverse processes important for brain tumors, including cell growth, survival, migration, invasion, and angiogenesis. Sphingosine kinase 1 (SphK1), one of the two isoenzymes that produce sphingosine-1-phosphate, is up-regulated in glioblastoma and has been linked to poor prognosis in patients with glioblastoma multiforme (GBM). In the present study, we found that a potent isotype-specific SphK1 inhibitor, SK1-I, suppressed growth of LN229 and U373 glioblastoma cell lines and nonestablished human GBM6 cells. SK1-I also enhanced GBM cell death and inhibited their migration and invasion. SK1-I rapidly reduced phosphorylation of Akt but had no significant effect on activation of extracellular signal-regulated kinase 1/2, another important survival pathway for GBM. Inhibition of the concomitant activation of the c-Jun-NH2-kinase pathway induced by SK1-I attenuated death of GBM cells. Importantly, SK1-I markedly reduced the tumor growth rate of glioblastoma xenografts, inducing apoptosis and reducing tumor vascularization, and enhanced the survival of mice harboring LN229 intracranial tumors. Our results support the notion that SphK1 may be an important factor in GBM and suggest that an isozyme-specific inhibitor of SphK1 deserves consideration as a new therapeutic agent for this disease. [Cancer Res 2009;69(17):6915–23]
Data from Contribution of Granulocyte Colony-Stimulating Factor to the Acute Mobilization of Endothelial Precursor Cells by Vascular Disrupting Agents
Authors: Shaked Yuval , Tang Terence , Woloszynek Jill , Daenen Laura G. , Man Shan , Xu Ping , Cai Shi-Rong , Arbeit Jeffrey M. , Voest Emile E. , Chaplin David J. , Smythe Jon , Harris Adrian , Nathan Paul , Judson Ian , Rustin Gordon , Bertolini Francesco , Link Daniel C. , Kerbel Robert S.
Published: March 2024

Abstract
Vascular disrupting agents (VDA) cause acute shutdown of abnormal established tumor vasculature, followed by massive intratumoral hypoxia and necrosis. However, a viable rim of tumor tissue invariably remains from which tumor regrowth rapidly resumes. We have recently shown that an acute systemic mobilization and homing of bone marrow–derived circulating endothelial precursor (CEP) cells could promote tumor regrowth following treatment with either a VDA or certain chemotherapy drugs. The molecular mediators of this systemic reactive host process are unknown. Here, we show that following treatment of mice with OXi-4503, a second-generation potent prodrug derivative of combretastatin-A4 phosphate, rapid increases in circulating plasma vascular endothelial growth factor, stromal derived factor-1 (SDF-1), and granulocyte colony-stimulating factor (G-CSF) levels are detected. With the aim of determining whether G-CSF is involved in VDA-induced CEP mobilization, mutant G-CSF-R−/− mice were treated with OXi-4503. We found that as opposed to wild-type controls, G-CSF-R−/− mice failed to mobilize CEPs or show induction of SDF-1 plasma levels. Furthermore, Lewis lung carcinomas grown in such mice treated with OXi-4503 showed greater levels of necrosis compared with tumors treated in wild-type mice. Evidence for rapid elevations in circulating plasma G-CSF, vascular endothelial growth factor, and SDF-1 were also observed in patients with VDA (combretastatin-A4 phosphate)-treated cancer. These results highlight the possible effect of drug-induced G-CSF on tumor regrowth following certain cytotoxic drug therapies, in this case using a VDA, and hence G-CSF as a possible therapeutic target. [Cancer Res 2009;69(19):7524–8]
Data from The Development of a Selective Cyclin-Dependent Kinase Inhibitor That Shows Antitumor Activity
Authors: Ali Simak , Heathcote Dean A. , Kroll Sebastian H.B. , Jogalekar Ashutosh S. , Scheiper Bodo , Patel Hetal , Brackow Jan , Siwicka Alekasandra , Fuchter Matthew J. , Periyasamy Manikandan , Tolhurst Robert S. , Kanneganti Seshu K. , Snyder James P. , Liotta Dennis C. , Aboagye Eric O. , Barrett Anthony G.M. , Coombes R. Charles
Published: March 2024

Abstract
Normal progression through the cell cycle requires the sequential action of cyclin-dependent kinases CDK1, CDK2, CDK4, and CDK6. Direct or indirect deregulation of CDK activity is a feature of almost all cancers and has led to the development of CDK inhibitors as anticancer agents. The CDK-activating kinase (CAK) plays a critical role in regulating cell cycle by mediating the activating phosphorylation of CDK1, CDK2, CDK4, and CDK6. As such, CDK7, which also regulates transcription as part of the TFIIH basal transcription factor, is an attractive target for the development of anticancer drugs. Computer modeling of the CDK7 structure was used to design potential potent CDK7 inhibitors. Here, we show that a pyrazolo[1,5-a]pyrimidine–derived compound, BS-181, inhibited CAK activity with an IC50 of 21 nmol/L. Testing of other CDKs as well as another 69 kinases showed that BS-181 only inhibited CDK2 at concentrations lower than 1 μmol/L, with CDK2 being inhibited 35-fold less potently (IC50 880 nmol/L) than CDK7. In MCF-7 cells, BS-181 inhibited the phosphorylation of CDK7 substrates, promoted cell cycle arrest and apoptosis to inhibit the growth of cancer cell lines, and showed antitumor effects in vivo. The drug was stable in vivo with a plasma elimination half-life in mice of 405 minutes after i.p. administration of 10 mg/kg. The same dose of drug inhibited the growth of MCF-7 human xenografts in nude mice. BS-181 therefore provides the first example of a potent and selective CDK7 inhibitor with potential as an anticancer agent. [Cancer Res 2009;69(15):6208–15]