bluuebunny/crossref_metadata_2025 huggingface dataset:
Data from miR-15a and miR-16 Are Implicated in Cell Cycle Regulation in a Rb-Dependent Manner and Are Frequently Deleted or Down-regulated in Non–Small Cell Lung Cancer
Authors: Bandi Nora , Zbinden Samuel , Gugger Mathias , Arnold Marlene , Kocher Verena , Hasan Lara , Kappeler Andreas , Brunner Thomas , Vassella Erik
Published: March 2024

Abstract
MicroRNAs (miRNA) are negative regulators of gene expression at the posttranscriptional level, which are involved in tumorigenesis. Two miRNAs, miR-15a and miR-16, which are located at chromosome 13q14, have been implicated in cell cycle control and apoptosis, but little information is available about their role in solid tumors. To address this question, we established a protocol to quantify miRNAs from laser capture microdissected tissues. Here, we show that miR-15a/miR-16 are frequently deleted or down-regulated in squamous cell carcinomas and adenocarcinomas of the lung. In these tumors, expression of miR-15a/miR-16 inversely correlates with the expression of cyclin D1. In non–small cell lung cancer (NSCLC) cell lines, cyclins D1, D2, and E1 are directly regulated by physiologic concentrations of miR-15a/miR-16. Consistent with these results, overexpression of these miRNAs induces cell cycle arrest in G1-G0. Interestingly, H2009 cells lacking Rb are resistant to miR-15a/miR-16–induced cell cycle arrest, whereas reintroduction of functional Rb resensitizes these cells to miRNA activity. In contrast, down-regulation of Rb in A549 cells by RNA interference confers resistance to these miRNAs. Thus, cell cycle arrest induced by these miRNAs depends on the expression of Rb, confirming that G1 cyclins are major targets of miR-15a/miR-16 in NSCLC. Our results indicate that miR-15a/miR-16 are implicated in cell cycle control and likely contribute to the tumorigenesis of NSCLC. [Cancer Res 2009;69(13):5553–9]
Data from Proteolytic Cleavage of Protein Tyrosine Phosphatase μ Regulates Glioblastoma Cell Migration
Authors: Burgoyne Adam M. , Phillips-Mason Polly J. , Burden-Gulley Susan M. , Robinson Shenandoah , Sloan Andrew E. , Miller Robert H. , Brady-Kalnay Susann M.
Published: March 2024

Abstract
Glioblastoma multiforme (GBM), the most common malignant primary brain tumor, represents a significant disease burden. GBM tumor cells disperse extensively throughout the brain parenchyma, and the need for tumor-specific drug targets and pharmacologic agents to inhibit cell migration and dispersal is great. The receptor protein tyrosine phosphatase μ (PTPμ) is a homophilic cell adhesion molecule. The full-length form of PTPμ is down-regulated in human glioblastoma. In this article, overexpression of full-length PTPμ is shown to suppress migration and survival of glioblastoma cells. Additionally, proteolytic cleavage is shown to be the mechanism of PTPμ down-regulation in glioblastoma cells. Proteolysis of PTPμ generates a series of proteolytic fragments, including a soluble catalytic intracellular domain fragment that translocates to the nucleus. Only proteolyzed PTPμ fragments are detected in human glioblastomas. Short hairpin RNA–mediated down-regulation of PTPμ fragments decreases glioblastoma cell migration and survival. A peptide inhibitor of PTPμ function blocks fragment-induced glioblastoma cell migration, which may prove to be of therapeutic value in GBM treatment. These data suggest that loss of cell surface PTPμ by proteolysis generates catalytically active PTPμ fragments that contribute to migration and survival of glioblastoma cells. [Cancer Res 2009;69(17):6960–8]
Data from Active Notch1 Confers a Transformed Phenotype to Primary Human Melanocytes
Authors: Pinnix Chelsea C. , Lee John T. , Liu Zhao-Jun , McDaid Ronan , Balint Klara , Beverly Levi J. , Brafford Patricia A. , Xiao Min , Himes Benjamin , Zabierowski Susan E. , Yashiro-Ohtani Yumi , Nathanson Katherine L. , Bengston Ana , Pollock Pamela M. , Weeraratna Ashani T. , Nickoloff Brian J. , Pear Warren S. , Capobianco Anthony J. , Herlyn Meenhard
Published: March 2024

Abstract
The importance of mitogen-activated protein kinase signaling in melanoma is underscored by the prevalence of activating mutations in N-Ras and B-Raf, yet clinical development of inhibitors of this pathway has been largely ineffective, suggesting that alternative oncogenes may also promote melanoma. Notch is an interesting candidate that has only been correlated with melanoma development and progression; a thorough assessment of tumor-initiating effects of activated Notch on human melanocytes would clarify the mounting correlative evidence and perhaps identify a novel target for an otherwise untreatable disease. Analysis of a substantial panel of cell lines and patient lesions showed that Notch activity is significantly higher in melanomas than their nontransformed counterparts. The use of a constitutively active, truncated Notch transgene construct (NIC) was exploited to determine if Notch activation is a “driving” event in melanocytic transformation or instead a “passenger” event associated with melanoma progression. NIC-infected melanocytes displayed increased proliferative capacity and biological features more reminiscent of melanoma, such as dysregulated cell adhesion and migration. Gene expression analyses supported these observations and aided in the identification of MCAM, an adhesion molecule associated with acquisition of the malignant phenotype, as a direct target of Notch transactivation. NIC-positive melanocytes grew at clonal density, proliferated in limiting media conditions, and also exhibited anchorage-independent growth, suggesting that Notch alone is a transforming oncogene in human melanocytes, a phenomenon not previously described for any melanoma oncogene. This new information yields valuable insight into the basic epidemiology of melanoma and launches a realm of possibilities for drug intervention in this deadly disease. [Cancer Res 2009;69(13):5312–20]
Data from Identification of a Protein, G0S2, That Lacks Bcl-2 Homology Domains and Interacts with and Antagonizes Bcl-2
Authors: Welch Christian , Santra Manas K. , El-Assaad Wissal , Zhu Xiaochun , Huber Wade E. , Keys Richard A. , Teodoro Jose G. , Green Michael R.
Published: March 2024

Abstract
The Bcl-2 family of proteins consists of both antiapoptotic and proapoptotic factors, which share sequence homology within conserved regions known as Bcl-2 homology domains. Interactions between Bcl-2 family members, as well as with other proteins, regulate apoptosis through control of mitochondrial membrane permeability and release of cytochrome c. Here we identify a novel regulator of apoptosis that lacks Bcl-2 homology domains but acts by binding Bcl-2 and modulating its antiapoptotic activity. To identify regulators of apoptosis, we performed expression profiling in human primary fibroblasts treated with tumor necrosis factor-α (TNF-α), a potent inflammatory cytokine that can regulate apoptosis and functions, at least in part, by inducing expression of specific genes through NF-κB. We found that the gene undergoing maximal transcriptional induction following TNF-α treatment was G0-G1 switch gene 2 (G0S2), the activation of which also required NF-κB. We show that G0S2 encodes a mitochondrial protein that specifically interacts with Bcl-2 and promotes apoptosis by preventing the formation of protective Bcl-2/Bax heterodimers. We further show that ectopic expression of G0S2 induces apoptosis in diverse human cancer cell lines in which endogenous G0S2 is normally epigenetically silenced. Our results reveal a novel proapoptotic factor that is induced by TNF-α through NF-κB and that interacts with and antagonizes Bcl-2. [Cancer Res 2009;69(17):6782–9]
Data from KLF6-SV1 Is a Novel Antiapoptotic Protein That Targets the BH3-Only Protein NOXA for Degradation and Whose Inhibition Extends Survival in an Ovarian Cancer Model
Authors: DiFeo Analisa , Huang Fei , Sangodkar Jaya , Terzo Esteban A. , Leake Devin , Narla Goutham , Martignetti John A.
Published: March 2024

Abstract
Defects in apoptosis are not only a hallmark of cancer initiation and progression but can also underlie the development of chemoresistance. How the tightly regulated cascade of protein-protein interactions between members of three competing protein families regulating the apoptotic cascade is subverted in tumor cells is incompletely understood. Here, we show that KLF6-SV1, whose overexpression is associated with poor survival in several different cancers and is an alternatively spliced isoform of the Krüppel-like tumor suppressor KLF6, is a critical prosurvival/antiapoptotic protein. KLF6-SV1 binds the proapoptotic BH3-only protein NOXA, which results in their mutual HDM2-dependent degradation. In turn, this increases the intracellular concentration of the prosurvival binding partner of NOXA, Mcl-1, and effectively blocks apoptosis. In an ovarian cancer model, systemically delivered small interfering RNA against KLF6-SV1 induces spontaneous apoptosis of tumor cells, decreases tumor burden, and restores cisplatin sensitivity in vivo. Moreover, i.p. delivery of siKLF6-SV1 RNA halts ovarian tumor progression and improves median and overall survival (progression-free for >15 months; P < 0.0002) in mice in a dose-dependent manner. Thus, KLF6-SV1 represents a novel regulator of protein interactions in the apoptotic cascade and a therapeutically targetable control point. [Cancer Res 2009;69(11):4733–41]
Data from Negative Regulation of β4 Integrin Transcription by Homeodomain-Interacting Protein Kinase 2 and p53 Impairs Tumor Progression
Authors: Bon Giulia , Di Carlo Selene E. , Folgiero Valentina , Avetrani Paolo , Lazzari Chiara , D'Orazi Gabriella , Brizzi Maria Felice , Sacchi Ada , Soddu Silvia , Blandino Giovanni , Mottolese Marcella , Falcioni Rita
Published: March 2024

Abstract
Increased expression of α6β4 integrin in several epithelial cancers promotes tumor progression; however, the mechanism underlying its transcriptional regulation remains unclear. Here, we show that depletion of homeodomain-interacting protein kinase 2 (HIPK2) activates β4 transcription that results in a strong increase of β4-dependent mitogen-activated protein kinase and Akt phosphorylation, anchorage-independent growth, and invasion. In contrast, stabilization of HIPK2 represses β4 expression in wild-type p53 (wtp53)-expressing cells but not in p53-null cells or cells expressing mutant p53, indicating that HIPK2 requires a wtp53 to inhibit β4 transcription. Consistent with our in vitro findings, a strong correlation between β4 overexpression and HIPK2 inactivation by cytoplasmic relocalization was observed in wtp53-expressing human breast carcinomas. Under loss of function of HIPK2 or p53, the p53 family members TAp63 and TAp73 strongly activate β4 transcription. These data, by revealing that β4 expression is transcriptionally repressed in tumors by HIPK2 and p53 to impair β4-dependent tumor progression, suggest that loss of p53 function favors the formation of coactivator complex with the TA members of the p53 family to allow β4 transcription. [Cancer Res 2009;69(14):5978–86]
Data from Up-regulation of miR-200 and let-7 by Natural Agents Leads to the Reversal of Epithelial-to-Mesenchymal Transition in Gemcitabine-Resistant Pancreatic Cancer Cells
Authors: Li Yiwei , VandenBoom Timothy G. , Kong Dejuan , Wang Zhiwei , Ali Shadan , Philip Philip A. , Sarkar Fazlul H.
Published: March 2024

Abstract
Pancreatic cancer is the fourth most common cause of cancer death in the United States, and the aggressiveness of pancreatic cancer is in part due to its intrinsic and extrinsic drug resistance characteristics, which are also associated with the acquisition of epithelial-to-mesenchymal transition (EMT). Emerging evidence also suggests that the processes of EMT are regulated by the expression status of many microRNAs (miRNA), which are believed to function as key regulators of various biological and pathologic processes during tumor development and progression. In the present study, we compared the expression of miRNAs between gemcitabine-sensitive and gemcitabine-resistant pancreatic cancer cells and investigated whether the treatment of cells with “natural agents” [3,3′-diindolylmethane (DIM) or isoflavone] could affect the expression of miRNAs. We found that the expression of miR-200b, miR-200c, let-7b, let-7c, let-7d, and let-7e was significantly down-regulated in gemcitabine-resistant cells, which showed EMT characteristics such as elongated fibroblastoid morphology, lower expression of epithelial marker E-cadherin, and higher expression of mesenchymal markers such as vimentin and ZEB1. Moreover, we found that reexpression of miR-200 by transfection studies or treatment of gemcitabine-resistant cells with either DIM or isoflavone resulted in the down-regulation of ZEB1, slug, and vimentin, which was consistent with morphologic reversal of EMT phenotype leading to epithelial morphology. These results provide experimental evidence, for the first time, that DIM and isoflavone could function as miRNA regulators leading to the reversal of EMT phenotype, which is likely to be important for designing novel therapies for pancreatic cancer. [Cancer Res 2009;69(16):6704–12]
Data from Bone Morphogenetic Proteins 2 and 5 Are Down-regulated in Adrenocortical Carcinoma and Modulate Adrenal Cell Proliferation and Steroidogenesis
Authors: Johnsen Inga K. , Kappler Roland , Auernhammer Christoph J. , Beuschlein Felix
Published: March 2024

Abstract
Bone morphogenetic proteins (BMP) have been shown to affect tumorigenesis in a variety of tumors. Quantitative PCR analysis revealed down-regulation of BMP2 and BMP5 in tissue samples from adrenocortical carcinoma and adrenocortical tumor cell lines compared with normal adrenal glands. Integrity of BMP-dependent pathways in these cell lines could be shown by activation of the Smad1/5/8 pathway with subsequent increase of ID protein expression upon incubation with BMP2 or BMP5. On a functional level, BMP treatment resulted in inhibition of cell proliferation and viability in a dose- and time-dependent manner. This growth inhibitory effect was associated with BMP-dependent reduction of AKT phosphorylation under baseline conditions and under insulin-like growth factor costimulation. Furthermore, steroidogenic function, including melanocortin-2 receptor and steroidogenic enzyme expressions, was profoundly reduced. In vitro demethylation treatment and overexpression of GATA6 resulted in reactivation of BMP-dependent pathways with concomitant modulation of steroidogenesis. Taken together, we show that loss of expression of members of the BMP family of ligands is a common finding in adrenocortical tumors and we provide evidence that BMP-dependent pathways are likely to be involved in the modulation of the malignant and functional phenotype of adrenocortical cancer cells. [Cancer Res 2009;69(14):5784–92]
Data from Immunodetection of DNA Repair Endonuclease ERCC1-XPF in Human Tissue
Authors: Bhagwat Nikhil R. , Roginskaya Vera Y. , Acquafondata Marie B. , Dhir Rajiv , Wood Richard D. , Niedernhofer Laura J.
Published: March 2024

Abstract
The high incidence of resistance to DNA-damaging chemotherapeutic drugs and severe side effects of chemotherapy have led to a search for biomarkers able to predict which patients are most likely to respond to therapy. ERCC1-XPF nuclease is required for nucleotide excision repair of helix-distorting DNA damage and the repair of DNA interstrand crosslinks. Thus, it is essential for several pathways of repair of DNA damage by cisplatin and related drugs, which are widely used in the treatment of non–small cell lung carcinoma and other late-stage tumors. Consequently, there is tremendous interest in measuring ERCC1-XPF expression in tumor samples. Many immunohistochemistry studies have been done, but the antibodies for ERCC1-XPF were not rigorously tested for antigen specificity. Herein, we survey a battery of antibodies raised against human ERCC1 or XPF for their specificity using ERCC1-XPF–deficient cells as a negative control. Antibodies were tested for the following applications: immunoblotting, immunoprecipitation from cell extracts, immunofluorescence detection in fixed cells, colocalization of ERCC1-XPF with UV radiation–induced DNA damage in fixed cells, and immunohistochemistry in paraffin-embedded samples. Although several commercially available antibodies are suitable for immunodetection of ERCC1-XPF in some applications, only a select subset is appropriate for detection of this repair complex in fixed specimens. The most commonly used antibody, 8F1, is not suitable for immunodetection in tissue. The results with validated antibodies reveal marked differences in ERCC1-XPF protein levels between samples and cell types. [Cancer Res 2009;69(17):6831–8]
Data from Tumor Vascular Changes Mediated by Inhibition of Oncogenic Signaling
Authors: Qayum Naseer , Muschel Ruth J. , Im Jae Hong , Balathasan Lukxmi , Koch Cameron J. , Patel Sonal , McKenna W. Gillies , Bernhard Eric J.
Published: March 2024

Abstract
Many inhibitors of the epidermal growth factor receptor (EGFR)-RAS-phosphatidylinositol 3-kinase (PI3K)-AKT signaling pathway are in clinical use or under development for cancer therapy. Here, we show that treatment of mice bearing human tumor xenografts with inhibitors that block EGFR, RAS, PI3K, or AKT resulted in prolonged and durable enhancement of tumor vascular flow, perfusion, and decreased tumor hypoxia. The vessels in the treated tumors had decreased tortuosity and increased internodal length accounting for the functional alterations. Inhibition of tumor growth cannot account for these results, as the drugs were given at doses that did not alter tumor growth. The tumor cell itself was an essential target, as HT1080 tumors that lack EGFR did not respond to an EGFR inhibitor but did respond with vascular alterations to RAS or PI3K inhibition. We extended these observations to spontaneously arising tumors in MMTV-neu mice. These tumors also responded to PI3K inhibition with decreased tumor hypoxia, increased vascular flow, and morphologic alterations of their vessels, including increased vascular maturity and acquisition of pericyte markers. These changes are similar to the vascular normalization that has been described after the antiangiogenic treatment of xenografts. One difficulty in the use of vascular normalization as a therapeutic strategy has been its limited duration. In contrast, blocking tumor cell RAS-PI3K-AKT signaling led to persistent vascular changes that might be incorporated into clinical strategies based on improvement of vascular flow or decreased hypoxia. These results indicate that vascular alterations must be considered as a consequence of signaling inhibition in cancer therapy. [Cancer Res 2009;69(15):6347–54]
Data from Cardiac Glycosides Inhibit p53 Synthesis by a Mechanism Relieved by Src or MAPK Inhibition
Authors: Wang Zhen , Zheng Min , Li Zhichuan , Li Ruiguo , Jia Lijun , Xiong Xiufang , Southall Noel , Wang Shaomeng , Xia Menghang , Austin Christopher P. , Zheng Wei , Xie Zijian , Sun Yi
Published: March 2024

Abstract
p53 is regulated at multiple levels. We report here that p53, in multiple lines of human cancer cells, is down-regulated by cardiac glycoside drugs digoxin and ouabain, potent inhibitors of Na+/K+-ATPase. These drugs reduced the basal levels of p53 protein at nanomolar concentrations in a dose-, time-, and cancer cell line–dependent manner, but independent of p53 status of wild-type or mutant. The drugs also reduced the levels of p53 induced by its activators as well as p53 transfected into human cancer cells, regardless of its status. Interestingly, the drugs had no effect on endogenous p53 in two immortalized human cell lines. Mechanistically, p53 reduction occurred not at the mRNA levels but at the protein levels, as a result of reduced protein synthesis rather than enhanced degradation. The cellular sensitivity to drug-induced p53 reduction was not associated with the levels of αsubunits of Na+/K+-ATPase in different cell lines. Although lowering extracellular K+ did not reduce p53 as did ouabain and digoxin, it did potentiate both digoxin- and ouabain-induced p53 reduction in sensitive lines. Finally, p53 reduction seems to be triggered by activation of Src/mitogen-activated protein kinase (MAPK) signaling pathways upon drug binding to the Na+/K+-ATPase and can be completely blocked by the inhibitors of Src or MAP/ERK kinase. This is the first report that cardiac glycoside drugs, by initiating the Src/MAPK signaling pathways, reduce the p53 levels via inhibition of p53 protein synthesis. The drugs may be useful in the treatment of human cancers with a gain-of-function p53 mutation. [Cancer Res 2009;69(16):6556–64]
Data from Follicle-Stimulating Hormone Peptide Can Facilitate Paclitaxel Nanoparticles to Target Ovarian Carcinoma In vivo
Authors: Zhang Xiao-yan , Chen Jun , Zheng Yu-fang , Gao Xiao-ling , Kang Yu , Liu Jia-chi , Cheng Ming-jun , Sun Hong , Xu Cong-jian
Published: March 2024

Abstract
Chemotherapy is an important treatment for ovarian cancer. However, conventional chemotherapy has inevitable drawbacks due to side effects from nonspecific biodistribution of the chemotherapeutic drugs. To solve such problem, targeted delivery approaches were developed. The targeted delivery approaches combine drug carriers with the targeting system and can preferentially bring drugs to the targeted sites. Follicle-stimulating hormone receptor (FSHR) is an ovarian cancer–specific receptor. By using a peptide derived from FSH (amino acids 33–53 of the FSH β chain, named as FSH33), we developed a conjugated nanoparticle, FSH33-NP, to target FSHR in ovarian cancer. FSH33-NP was tested for recognition specificity and uptake efficiency on FSHR-expressing cells. Then, the antitumor efficiency of paclitaxel (PTX)-loaded FSH33-NP (FSH33-NP-PTX) was determined. FSH33-NP-PTX displayed stronger antiproliferation and antitumor effects compared with free PTX or naked PTX-loaded nanoparticles (NP-PTX) both in vitro and in vivo. In summary, this novel FSH33-NP delivery system showed very high selectivity and efficacy for FSHR-expressing tumor tissues. Therefore, it has good potential to become a new therapeutic approach for patients with ovarian cancer. [Cancer Res 2009;69(16):6506–14]
Data from Identification of a Subpopulation of Macrophages in Mammary Tumor–Bearing Mice That Are Neither M1 nor M2 and Are Less Differentiated
Authors: Torroella-Kouri Marta , Silvera Risset , Rodriguez Dayron , Caso Raul , Shatry Alwi , Opiela Shannon , Ilkovitch Dan , Schwendener Reto A. , Iragavarapu-Charyulu Vijaya , Cardentey Yoslayma , Strbo Natasa , Lopez Diana M.
Published: March 2024

Abstract
Systemic and local immune deficiency is associated with cancer, and the role of M2 tumor-associated macrophages in this phenomenon is well recognized. However, the immune status of macrophages from peripheral compartments in tumor hosts is unclear. Peritoneal macrophages (PEM) are derived from circulating monocytes and recruited to the peritoneal cavity where they differentiate into macrophages. We have previously shown that PEMs from mice bearing D1-DMBA-3 mammary tumors (T-PEM) are deficient in inflammatory functions and that this impairment is associated with diminished expression of transcription factors nuclear factor κB and CAAT/enhancer-binding protein. We now provide evidence that T-PEMs display neither M1 nor M2 phenotypes, yet exhibit deficiencies in the expression of several inflammatory cytokines and various proinflammatory signaling pathways. Moreover, due to nuclear factor κB down-regulation, increased apoptosis was observed in T-PEMs. We report for the first time that macrophage depletion is associated with increased macrophage progenitors in bone marrow. Furthermore, T-PEMs have a lower expression of macrophage differentiation markers F4/80, CD68, CD115, and CD11b, whereas Gr-1 is up-regulated. Our results suggest that T-PEMs are less differentiated and represent a newly derived population from blood monocytes. Lastly, we show that transforming growth factor-β and prostaglandin E2, two immunosuppressive tumor-derived factors, may be involved in this phenomenon. [Cancer Res 2009;69(11):4800–9]
Data from Cyclin D1 Degradation Is Sufficient to Induce G1 Cell Cycle Arrest despite Constitutive Expression of Cyclin E2 in Ovarian Cancer Cells
Authors: Masamha Chioniso Patience , Benbrook Doris Mangiaracina
Published: March 2024

Abstract
D- and E-type cyclins mediate G1-S phase cell cycle progression through activation of specific cyclin-dependent kinases (cdk) that phosphorylate the retinoblastoma protein (pRb), thereby alleviating repression of E2F-DP transactivation of S-phase genes. Cyclin D1 is often overexpressed in a variety of cancers and is associated with tumorigenesis and metastasis. Loss of cyclin D can cause G1 arrest in some cells, but in other cellular contexts, the downstream cyclin E protein can substitute for cyclin D and facilitate G1-S progression. The objective of this study was to determine if a flexible heteroarotinoid anticancer compound, SHetA2, regulates cell cycle proteins and cell cycle progression in ovarian cancer cells. SHetA2 induced cyclin D1 phosphorylation, ubiquitination, and proteasomal degradation, causing G1 arrest in ovarian cancer cells despite continued cyclin E2 expression and independently of p53 and glycogen synthase kinase-3β. Cyclin D1 loss inhibited pRb S780 phosphorylation by cyclin D1-cdk4/6 and released p21 from cyclin D1-cdk4/6-p21 protein complexes to form cyclin E2-cdk2-p21 complexes, which repressed phosphorylation of pRb S612 by cyclin E2-cdk2 and ultimately E2F-DP transcriptional activity. G1 arrest was prevented by overexpression or preventing degradation of cyclin D1 but not by restoration of pRb S612 phosphorylation through p21 knockdown. In conclusion, we show that loss of cyclin D1 in ovarian cancer cells treated with SHetA2 is sufficient to induce G1 cell cycle arrest and this strategy is not impeded by the presence of cyclin E2. Therefore, cyclin D1 is a sufficient therapeutic target in ovarian cancer cells. [Cancer Res 2009;69(16):6565–72]
Data from The Role of HuR in Gemcitabine Efficacy in Pancreatic Cancer: HuR Up-regulates the Expression of the Gemcitabine Metabolizing Enzyme Deoxycytidine Kinase
Authors: Costantino Christina L. , Witkiewicz Agnieszka K. , Kuwano Yuki , Cozzitorto Joseph A. , Kennedy Eugene P. , Dasgupta Abhijit , Keen Judith C. , Yeo Charles J. , Gorospe Myriam , Brody Jonathan R.
Published: March 2024

Abstract
RNA-binding protein HuR binds U- or AU-rich sequences in the 3′-untranslated regions of target mRNAs, stabilizing them and/or modulating their translation. Given the links of HuR with cancer, we studied the consequences of modulating HuR levels in pancreatic cancer cells. HuR-overexpressing cancer cells, in some instances, are roughly up to 30-fold more sensitive to treatment with gemcitabine, the main chemotherapeutic component of treatment regimens for pancreatic ductal adenocarcinoma (PDA), compared with control cells. In pancreatic cancer cells, HuR associates with deoxycytidine kinase (dCK) mRNA, which encodes the enzyme that metabolizes and thereby activates gemcitabine. Gemcitabine exposure to pancreatic cancer cells enriches the association between HuR and dCK mRNA and increases cytoplasmic HuR levels. Accordingly, HuR overexpression elevates, whereas HuR silencing reduces, dCK protein expression in pancreatic cancer cells. In a clinical correlate study of gemcitabine treatment, we found a 7-fold increase in risk of mortality in PDA patients with low cytoplasmic HuR levels compared with patients with high HuR levels, after adjusting for other treatments and demographic variables. These data support the notion that HuR is a key mediator of gemcitabine efficacy in cancer cells, at least in part through its ability to regulate dCK levels posttranscriptionally. We propose that HuR levels in PDA modulate the therapeutic efficacy of gemcitabine, thus serving as a marker of the clinical utility of this common chemotherapeutic agent and a potential target for intervention in pancreatic cancer. [Cancer Res 2009;69(11):4567–72]
Data from Comparison of Human and Rat Uterine Leiomyomata: Identification of a Dysregulated Mammalian Target of Rapamycin Pathway
Authors: Crabtree Judy S. , Jelinsky Scott A. , Harris Heather A. , Choe Sung E. , Cotreau Monette M. , Kimberland Michelle L. , Wilson Ewa , Saraf Kathryn A. , Liu Wei , McCampbell Adrienne S. , Dave Bhuvanesh , Broaddus Russell R. , Brown Eugene L. , Kao Wenling , Skotnicki Jerauld S. , Abou-Gharbia Magid , Winneker Richard C. , Walker Cheryl L.
Published: March 2024

Abstract
Uterine leiomyomata, or fibroids, are benign tumors of the uterine myometrium that significantly affect up to 30% of reproductive-age women. Despite being the primary cause of hysterectomy in the United States, accounting for up to 200,000 procedures annually, the etiology of leiomyoma remains largely unknown. As a basis for understanding leiomyoma pathogenesis and identifying targets for pharmacotherapy, we conducted transcriptional profiling of leiomyoma and unaffected myometrium from humans and Eker rats, the best characterized preclinical model of leiomyomata. A global comparison of mRNA from leiomyoma versus myometrium in human and rat identified a highly significant overlap of dysregulated gene expression in leiomyomata. An unbiased pathway analysis using a method of gene-set enrichment based on the sigPathway algorithm detected the mammalian target of rapamycin (mTOR) pathway as one of the most highly up-regulated pathways in both human and rat tumors. To validate this pathway as a therapeutic target for uterine leiomyomata, preclinical studies were conducted in Eker rats. These rats develop uterine leiomyomata as a consequence of loss of Tsc2 function and up-regulation of mTOR signaling. Inhibition of mTOR in female Eker rats with the rapamycin analogue WAY-129327 for 2 weeks decreased mTOR signaling and cell proliferation in tumors, and treatment for 4 months significantly decreased tumor incidence, multiplicity, and size. These results identify dysregulated mTOR signaling as a component of leiomyoma etiology across species and directly show the dependence of uterine leiomyomata with activated mTOR on this signaling pathway for growth. [Cancer Res 2009;69(15):6171–8]
Data from Loss of Histone Deacetylase 4 Causes Segregation Defects during Mitosis of p53-Deficient Human Tumor Cells
Authors: Cadot Bruno , Brunetti Mirko , Coppari Sabina , Fedeli Silvia , de Rinaldis Emanuele , Russo Claudio Dello , Gallinari Paola , De Francesco Raffaele , Steinkühler Christian , Filocamo Gessica
Published: March 2024

Abstract
We investigated the role of histone deacetylase 4 (HDAC4) using RNA interference (RNAi) and knockout cells to specifically address its role in cell cycle progression in tumor and normal cells. Ablation of HDAC4 led to growth inhibition in human tumor cells but not to detectable effects in normal human dermal fibroblasts (NHDF) or myelopoietic progenitors. HDAC4−/+ or HDAC4−/− murine embryonic fibroblasts showed no detectable growth defects. On the other hand, HDAC4 RNAi in HeLa cells produced mitotic arrest followed by caspase-dependent apoptosis. Mitotically arrested cells showed chromosome segregation defects. Even though the growth of both p53–wild-type and p53-null tumor cells were affected by HDAC4 ablation, segregation defects were observed only in p53-null cells. HDAC4 associates with the PP2A-B56 regulatory subunit, which is known to be involved in chromosome segregation, and RNAi of either the structural subunit A or the regulatory subunit B56 of PP2A also caused chromosome segregation defects. We conclude that HDAC4 is required for cell cycle progression of tumor cells by multiple mechanisms, one of which seems to be specific to p53-deficient cells through chromosome segregation defects. On the contrary, HDAC4 is not required for the progression of NHDF. We therefore suggest that systemic selective interference with the expression or function of HDAC4 is expected to have a significant therapeutic window, in particular, for p53-deficient tumors. [Cancer Res 2009;69(15):6074–82]
Data from Computational Identification of a p38SAPK-Regulated Transcription Factor Network Required for Tumor Cell Quiescence
Authors: Adam Alejandro P. , George Ajish , Schewe Denis , Bragado Paloma , Iglesias Bibiana V. , Ranganathan Aparna C. , Kourtidis Antonis , Conklin Douglas S. , Aguirre-Ghiso Julio A.
Published: March 2024

Abstract
The stress-activated kinase p38 plays key roles in tumor suppression and induction of tumor cell dormancy. However, the mechanisms behind these functions remain poorly understood. Using computational tools, we identified a transcription factor (TF) network regulated by p38α/β and required for human squamous carcinoma cell quiescence in vivo. We found that p38 transcriptionally regulates a core network of 46 genes that includes 16 TFs. Activation of p38 induced the expression of the TFs p53 and BHLHB3, while inhibiting c-Jun and FoxM1 expression. Furthermore, induction of p53 by p38 was dependent on c-Jun down-regulation. Accordingly, RNAi down-regulation of BHLHB3 or p53 interrupted tumor cell quiescence, while down-regulation of c-Jun or FoxM1 or overexpression of BHLHB3 in malignant cells mimicked the onset of quiescence. Our results identify components of the regulatory mechanisms driving p38-induced cancer cell quiescence. These may regulate dormancy of residual disease that usually precedes the onset of metastasis in many cancers. [Cancer Res 2009;69(14):5664–72]
Data from Anticancer Activity of CX-3543: A Direct Inhibitor of rRNA Biogenesis
Authors: Drygin Denis , Siddiqui-Jain Adam , O'Brien Sean , Schwaebe Michael , Lin Amy , Bliesath Josh , Ho Caroline B. , Proffitt Chris , Trent Katy , Whitten Jeffrey P. , Lim John K. C. , Von Hoff Daniel , Anderes Kenna , Rice William G.
Published: March 2024

Abstract
Hallmark deregulated signaling in cancer cells drives excessive ribosome biogenesis within the nucleolus, which elicits unbridled cell growth and proliferation. The rate-limiting step of ribosome biogenesis is synthesis of rRNA (building blocks of ribosomes) by RNA Polymerase I (Pol I). Numerous kinase pathways and products of proto-oncogenes can up-regulate Pol I, whereas tumor suppressor proteins can inhibit rRNA synthesis. In tumorigenesis, activating mutations in certain cancer-associated kinases and loss-of-function mutations in tumor suppressors lead to deregulated signaling that stimulates Pol I transcription with resultant increases in ribosome biogenesis, protein synthesis, cell growth, and proliferation. Certain anticancer therapeutics, such as cisplatin and 5-fluorouracil, reportedly exert, at least partially, their activity through disruption of ribosome biogenesis, yet many prime targets for anticancer drugs within the ribosome synthetic machinery of the nucleolus remain largely unexploited. Herein, we describe CX-3543, a small molecule nucleolus-targeting agent that selectively disrupts nucleolin/rDNA G-quadruplex complexes in the nucleolus, thereby inhibiting Pol I transcription and inducing apoptosis in cancer cells. CX-3543 is the first G-quadruplex interactive agent to enter human clinical trials, and it is currently under evaluation against carcinoid/neuroendocrine tumors in a phase II clinical trial. [Cancer Res 2009;69(19):7653–61]
Data from hCLCA2 Is a p53-Inducible Inhibitor of Breast Cancer Cell Proliferation
Authors: Walia Vijay , Ding Ming , Kumar Sumit , Nie Daotai , Premkumar Louis S. , Elble Randolph C.
Published: March 2024

Abstract
hCLCA2 is frequently down-regulated in breast cancer and is a candidate tumor suppressor gene. We show here that the hCLCA2 gene is strongly induced by p53 in response to DNA damage. Adenoviral expression of p53 induces hCLCA2 in a variety of breast cell lines. Further, we find that p53 binds to consensus elements in the hCLCA2 promoter and mutation of these sites abolishes p53-responsiveness and induction by DNA damage. Adenoviral transduction of hCLCA2 into immortalized cells induces p53, CDK inhibitors p21 and p27, and cell cycle arrest by 24 hours, and caspase induction and apoptosis by 40 hours postinfection. Transduction of the malignant tumor cell line BT549 on the other hand does not induce p53, p21, or p27 but instead induces apoptosis directly and more rapidly. Knockout and knockdown studies indicate that growth inhibition and apoptosis are signaled via multiple pathways. Conversely, suppression of hCLCA2 by RNA interference enhances proliferation of MCF10A and reduces sensitivity to doxorubicin. Gene expression profiles indicate that hCLCA2 levels are strongly predictive of tumor cell sensitivity to doxorubicin and other chemotherapeutics. Because certain Cl− channels are proposed to promote apoptosis by reducing intracellular pH, we tested whether, and established that, hCLCA2 enhances Cl− current in breast cancer cells and reduces pH to ∼6.7. These results reveal hCLCA2 as a novel p53-inducible growth inhibitor, explain how its down-regulation confers a survival advantage to tumor cells, and suggest both prognostic and therapeutic applications. [Cancer Res 2009;69(16):6624–32]
Data from HIPK2 Regulation by MDM2 Determines Tumor Cell Response to the p53-Reactivating Drugs Nutlin-3 and RITA
Authors: Rinaldo Cinzia , Prodosmo Andrea , Siepi Francesca , Moncada Alice , Sacchi Ada , Selivanova Galina , Soddu Silvia
Published: March 2024

Abstract
In the past few years, much effort has been devoted to show the single-target specificity of nongenotoxic, p53 reactivating compounds. However, the divergent biological responses induced by the different compounds, even in the same tumor cells, demand additional mechanistic insights, whose knowledge may lead to improved drug design or selection of the most potent drug combinations. To address the molecular mechanism underlying induction of mitotic arrest versus clinically more desirable apoptosis, we took advantage of two MDM2 antagonists, Nutlin-3 and RITA, which respectively produce these two outcomes. We show that, along with p53 reactivation, the proapoptotic p53-activator HIPK2 is degraded by MDM2 in Nutlin-3–treated cells, but activated by transiently reduced MDM2 levels in RITA-treated ones. Gain- and loss-of-function experiments revealed the functional significance of MDM2-mediated HIPK2 regulation in cell decision between mitotic arrest and apoptosis in both types of p53 reactivation. These data indicate that strategies of p53 reactivation by MDM2 inhibition should also take into consideration MDM2 targets other than p53, such as the apoptosis activator HIPK2. [Cancer Res 2009;69(15):6241–8]
Data from White Adipose Tissue Cells Are Recruited by Experimental Tumors and Promote Cancer Progression in Mouse Models
Authors: Zhang Yan , Daquinag Alexes , Traktuev Dmitry O. , Amaya-Manzanares Felipe , Simmons Paul J. , March Keith L. , Pasqualini Renata , Arap Wadih , Kolonin Mikhail G.
Published: March 2024

Abstract
The connection between obesity and accelerated cancer progression has been established, but the mediating mechanisms are not well understood. We have shown that stromal cells from white adipose tissue (WAT) cooperate with the endothelium to promote blood vessel formation through the secretion of soluble trophic factors. Here, we hypothesize that WAT directly mediates cancer progression by serving as a source of cells that migrate to tumors and promote neovascularization. To test this hypothesis, we have evaluated the recruitment of WAT-derived cells by tumors and the effect of their engraftment on tumor growth by integrating a transgenic mouse strain engineered for expansion of traceable cells with established allograft and xenograft cancer models. Our studies show that entry of adipose stromal and endothelial cells into systemic circulation leads to their homing to and engraftment into tumor stroma and vasculature, respectively. We show that recruitment of adipose stromal cells by tumors is sufficient to promote tumor growth. Finally, we show that migration of stromal and vascular progenitor cells from WAT grafts to tumors is also associated with acceleration of cancer progression. These results provide a biological insight for the clinical association between obesity and cancer, thus outlining potential avenues for preventive and therapeutic strategies. [Cancer Res 2009;69(12):5259–66]
Data from Host Genetic Variants in the Interleukin-6 Promoter Predict Poor Outcome in Patients with Estrogen Receptor-Positive, Node-Positive Breast Cancer
Authors: DeMichele Angela , Gray Robert , Horn Michelle , Chen Jinbo , Aplenc Richard , Vaughan William P. , Tallman Martin S.
Published: March 2024

Abstract
Interleukin-6 modulates immune response, estrogen production, and growth pathways in breast cancer. We evaluated the effect of several common, functional interleukin-6 promoter variants in node-positive breast cancer patients enrolled on a multicenter, cooperative group, adjuvant chemotherapy trial to determine whether these variants were associated with clinical outcome overall and by estrogen receptor tumor phenotype. Genomic DNA and clinical data were collected from a clinical trial of adjuvant anthracycline-based chemotherapy followed by randomization to high-dose cyclophosphamide/thiotepa or observation (Intergroup Trial 0121). Genotyping for -174G>C (rs1800795), -597G>A (rs1800797), and -572G>C (rs1800796) was done by site-specific PCR and PyroSequencing, whereas the -373AnTn repeat was directly sequenced. Log-rank tests and Cox modeling were used to compare outcomes by genotype/haplotype and other factors. Three hundred forty-six patients (64% of trial) had corresponding genotype/clinical data available and did not differ from overall trial participants. After adjustment, patients with estrogen receptor-positive tumors and genotypes 597 GG or 174 GG had significantly worse disease-free survival [hazard ratio (HR), 1.6; P = 0.02 and HR, 1.71; P = 0.007, respectively], whereas the 373 8A12T repeat appeared to be protective (HR, 0.62; P = 0.02). The presence of at least one copy of the haplotype ([-597G, -572G, -373[10A/11T], -174G]) was associated with worse disease-free survival (HR, 1.46; P = 0.04). Kaplan-Meier plots show that all patients in this group relapsed by 24 months from diagnosis. This poor-risk haplotype was quite common overall (estimated frequency, 0.20) and twice as frequent among Blacks (estimated frequency, 0.41). [Cancer Res 2009;69(10):4184–91]
Data from Inhibition of Tumor Cell Growth, Invasion, and Metastasis by EXEL-2880 (XL880, GSK1363089), a Novel Inhibitor of HGF and VEGF Receptor Tyrosine Kinases
Authors: Qian Fawn , Engst Stefan , Yamaguchi Kyoko , Yu Peiwen , Won Kwang-Ai , Mock Lillian , Lou Tracy , Tan Jenny , Li Connie , Tam Danny , Lougheed Julie , Yakes F. Michael , Bentzien Frauke , Xu Wei , Zaks Tal , Wooster Richard , Greshock Joel , Joly Alison H.
Published: March 2024

Abstract
The Met receptor tyrosine kinase and its ligand, hepatocyte growth factor (HGF), are overexpressed and/or activated in a wide variety of human malignancies. Vascular endothelial growth factor (VEGF) receptors are expressed on the surface of vascular endothelial cells and cooperate with Met to induce tumor invasion and vascularization. EXEL-2880 (XL880, GSK1363089) is a small-molecule kinase inhibitor that targets members of the HGF and VEGF receptor tyrosine kinase families, with additional inhibitory activity toward KIT, Flt-3, platelet-derived growth factor receptor β, and Tie-2. Binding of EXEL-2880 to Met and VEGF receptor 2 (KDR) is characterized by a very slow off-rate, consistent with X-ray crystallographic data showing that the inhibitor is deeply bound in the Met kinase active site cleft. EXEL-2880 inhibits cellular HGF-induced Met phosphorylation and VEGF-induced extracellular signal-regulated kinase phosphorylation and prevents both HGF-induced responses of tumor cells and HGF/VEGF-induced responses of endothelial cells. In addition, EXEL-2880 prevents anchorage-independent proliferation of tumor cells under both normoxic and hypoxic conditions. In vivo, these effects produce significant dose-dependent inhibition of tumor burden in an experimental model of lung metastasis. Collectively, these data indicate that EXEL-2880 may prevent tumor growth through a direct effect on tumor cell proliferation and by inhibition of invasion and angiogenesis mediated by HGF and VEGF receptors. [Cancer Res 2009;69(20):8009–16]
Data from Glioma Tumor Stem-Like Cells Promote Tumor Angiogenesis and Vasculogenesis via Vascular Endothelial Growth Factor and Stromal-Derived Factor 1
Authors: Folkins Chris , Shaked Yuval , Man Shan , Tang Terence , Lee Christina R. , Zhu Zhenping , Hoffman Robert M. , Kerbel Robert S.
Published: March 2024

Abstract
Cancer stem cells (CSC) are predicted to be critical drivers of tumor progression due to their self-renewal capacity and limitless proliferative potential. An emerging area of research suggests that CSC may also support tumor progression by promoting tumor angiogenesis. To investigate how CSC contribute to tumor vascular development, we used an approach comparing tumor xenografts of the C6 glioma cell line containing either a low or a high fraction of CSC. Compared with CSC-low tumors, CSC-high tumors exhibited increased microvessel density and blood perfusion and induced increased mobilization and tumor recruitment of bone marrow–derived endothelial progenitor cells (EPC). CSC-high C6 cell cultures also induced higher levels of endothelial cell proliferation and tubule organization in vitro compared with CSC-low cultures. CSC-high cultures and tumors expressed increased levels of the proangiogenic factors vascular endothelial growth factor and stromal-derived factor1, and when signaling by either factor was blocked, all aspects of angiogenesis observed in CSC-high cultures andtumors, including microvessel density, perfusion, EPC mobilization/recruitment, and stimulation of endothelial cellactivity, were reduced to levels comparable with those observed in CSC-low cultures/tumors. These results suggest that CSC contribute to tumor angiogenesis by promoting both local endothelial cell activity and systemic angiogenic processes involving bone marrow–derived EPC in a vascular endothelial growth factor–dependent and stromal-derived factor 1–dependent manner. [Cancer Res 2009;69(18):7243–51]
Data from Patterns of Gene Expression and Copy-Number Alterations in von-Hippel Lindau Disease-Associated and Sporadic Clear Cell Carcinoma of the Kidney
Authors: Beroukhim Rameen , Brunet Jean-Philippe , Di Napoli Arianna , Mertz Kirsten D. , Seeley Apryle , Pires Maira M. , Linhart David , Worrell Robert A. , Moch Holger , Rubin Mark A. , Sellers William R. , Meyerson Matthew , Linehan W. Marston , Kaelin William G. , Signoretti Sabina
Published: March 2024

Abstract
Recent insights into the role of the von-Hippel Lindau (VHL) tumor suppressor gene in hereditary and sporadic clear-cell renal cell carcinoma (ccRCC) have led to new treatments for patients with metastatic ccRCC, although virtually all patients eventually succumb to the disease. We performed an integrated, genome-wide analysis of copy-number changes and gene expression profiles in 90 tumors, including both sporadic and VHL disease-associated tumors, in hopes of identifying new therapeutic targets in ccRCC. We identified 14 regions of nonrandom copy-number change, including 7 regions of amplification (1q, 2q, 5q, 7q, 8q, 12p, and 20q) and 7 regions of deletion (1p, 3p, 4q, 6q, 8p, 9p, and 14q). An analysis aimed at identifying the relevant genes revealed VHL as one of three genes in the 3p deletion peak, CDKN2A and CDKN2B as the only genes in the 9p deletion peak, and MYC as the only gene in the 8q amplification peak. An integrated analysis to identify genes in amplification peaks that are consistently overexpressed among amplified samples confirmed MYC as a potential target of 8q amplification and identified candidate oncogenes in the other regions. A comparison of genomic profiles revealed that VHL disease-associated tumors are similar to a subgroup of sporadic tumors and thus more homogeneous overall. Sporadic tumors without evidence of biallelic VHL inactivation fell into two groups: one group with genomic profiles highly dissimilar to the majority of ccRCC and a second group with genomic profiles that are much more similar to tumors with biallelic inactivation of VHL. [Cancer Res 2009;69(11):4674–81]