bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract 803: HOXB7 functions as a co-activator of estrogen receptor in the development of tamoxifen resistance
Authors: Jin Kideok , wen Teo Wei , Yoshida Takahiro , Park Sunju , Sukumar Saraswati
Published: August 2012

Multiple factors including long term treatment with tamoxifen are involved in the development of selective estrogen receptor modulator (SERM)-resistance in ERα positive breast cancer. Increased expression of HER family members can also directly alter cellular responses to tamoxifen, but the mechanism underlying the increased expression of the HERs is not clear. In this report we show that HOXB7 interacts with ERα, and together they bind to the promoter or enhancer regions of ERα-regulated genes to enhance their transcription activity. We found a number of novel HOXB7 binding sites at promoter regions, intron regions and adjacent to ER-binding sites in ER-regulated genes through HOXB7 ChIP on chiP using an Affymetrix promoter array. Potentially, HOXB7 and ERα may co-regulate about 84% of ERα-target genes. HOXB7 overexpression renders MCF-7 cells resistant to tamoxifen. Overexpression of HOXB7 results in upregulation of HER2 and ERα target genes while knockdown of HOXB7 with siRNA in tamoxifen-resistant cell lines causes decrease of HER2 and ERα target genes expression and loss of tamoxifen resistance. Our data shows that to mediate upregulation of HER2 and ER-target genes occurring in tamoxifen resistance, the HOXB7-ERα complex recruits ERα coactivators and promotes HER2- and ER-target genes transcriptional activity through direct binding to the HER2 enhancer and regulatory regions of ER target genes. However, depletion of HOXB7 negatively affects the binding affinity of its cofactors to the HER2 enhancer element and ER-binding sites. Also, we found that miR196a might control HOXB7 expression; reducing miR196a levels in tamoxifen-resistant cells causes an increase of HOXB7 expression. Further, miRNA 196a is regulated by c-MYC which undergoes stabilization through the EGFR-HER2 signaling pathway. These findings implicate overexpression of HOXB7 as a key event in the initiation and maintenance of tamoxifen resistance. These studies suggest that HOXB7 acts as a key regulator orchestrating two major groups of target molecules, ERα and HER2, in the oncogene hierarchy. Therefore, we have provided additional evidence that supports the thesis that functional antagonism of HOXB7 has the potential to circumvent tamoxifen resistance.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 803. doi:1538-7445.AM2012-803
Abstract 804: The impact of aromatase inhibitor therapy on ER co-regulator expression and interaction
Authors: Bourgo Ryan J. , Greene Geoffrey L.
Published: August 2012

Estrogen receptor alpha (ERα) is a member of the nuclear receptor family and is currently recognized as the most defining metric in breast cancer diagnosis and treatment. Roughly 70% of all breast cancer patients present with ERα-positive, hormone sensitive disease, and the majority of these women are post-menopausal. Because post-menopausal women require the aromatase enzyme for estrogen synthesis, the first line of treatment for these patients is aromatase inhibitor (AI) therapy. Despite the number of women whose primary disease responds positively, a significant fraction of patients fail to gain any clinical benefit due to intrinsic resistance, or eventually relapse due to acquired resistance to AI therapy. Currently, the biochemical changes underlying both intrinsic and acquired resistance to AI therapy is yet unknown; thus, resistance to AI therapy remains a significant clinical obstacle for a large fraction of breast cancer patients. Here, we investigate the impact of ERα co-regulators on intrinsic and acquired AI resistance in breast cancer. In vitro administration of testosterone to wild-type MCF-7, T47-D, or ZR75-1 cells is capable of offering a significant ERα-dependent proliferative advantage, suggesting an active role for aromatase in these cells. Interestingly, aromatase inhibitor (Anastrazole) treatment of these cells alters the expression of specific ERα co-regulators independent of ligand. Furthermore, interaction between ERα and individual co-regulators is altered after treatment with estradiol or testosterone, and is impacted by Anastrazole treatment acutely. While these findings are preliminary, further investigation is on-going and promises to provide critical insight into the contributions of ERα co-regulators to the short- and long-term response to AI-mediated estrogen deprivation, as well as establish the alterations in ERα-mediated promoter occupancy and gene regulation that contribute to intrinsic and acquired AI resistance.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 804. doi:1538-7445.AM2012-804
Abstract 820: Somatic mutations to identify tumors for highly selective chemosensitization by Nrf2 depletion
Authors: Batist Gerald , Wu JianHui , Abdulkassim Tahar , Bendavit Gabriel , Abramovitz Mark
Published: August 2012

Therapeutic resistance remains a critical challenge in cancer treatment. Effective chemosensitizers must target more than a single mechanism of resistance and must also selectively sensitize only tumor and not normal tissue. Nrf2 is a transcription factor that regulates a battery of cytoprotective genes, and is shown in multiple experimental systems to have a significant impact on sensitivity to cytotoxic treatments. Regulation of Nrf2 levels is largely post-translationally, as a result of its physical interaction with adapter protein Keap1, which targets it for proteosomal degradation. An increasing number of human tumors and cancer cell lines are found to have loss of function mutations in Keap1 that results in constitutively elevated Nrf2 and drug resistance. In such circumstances alternative pathways for Nrf2 degradation may predominate, including the PI3kinase pathway protein GSK-3β, which exports Nrf2 from the nucleus to the proteosome. When relatively common somatic mutations in the PI3kinase pathway result in phosphorylation of GSK-3β at Ser9, it is inactivated. However, the addition of a PI3kinase pathway inhibitors increases GSK-3β, depletes Nrf2 and significantly sensitizes these cells. We are further exploring mechanisms, and at the same time screening biobanks of various tumors to determine the incidence of somatic loss of function mutations in Keap1 and mutations in the Pi3K pathway that activate it. This would represent a molecular signature of tumors that would be highly selectively sensitized by this strategy.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 820. doi:1538-7445.AM2012-820
Abstract 829: Down-regulation of insulin-like growth factor-binding protein 7 in cisplatin-resistant non-small cell lung cancer
Authors: Okamura Jun , Huang Yiping , Brait Mariana , Chang Xiaofei , Sidransky David , Kim Myoung S.
Published: August 2012

Cisplatin is an effective anticancer drug used to treat many types of cancer, including non-small cell lung carcinoma (NSCLCs), but development of resistance is the primary impediment in cancer treatment. Insulin-like growth factor-binding protein 7 (IGFBP7) is a secreted tumor suppressor that is inactivated in human lung cancer. IGFBP7 is known to alter sensitivity to interferon-based anticancer therapy, and here, we examined loss of IGFBP7 as a potential contributor to chemo-resistance to cisplatin. The transcriptional level of IGFBP7 was decreased in cisplatin-resistant human cancer cell lines and NSCLC xenografts. IGFBP7 knock-down increased cellular resistance to cisplatin and increased the level of mitogen-activated protein kinase phosphatases (MKP) 3 levels. The expression of MKP3 increased in a cisplatin-resistant NSCLC cell line and lung xenografts. MKP3 knock-down increased IGFBP7 level, indicating that MKP3 regulates IGFBP7. These findings suggest a novel molecular mechanism responsible for the tumor suppressive function of IGFBP7 in cisplatin-resistant human lung cancer and could lead to the development of IGFBP7 as a cisplatin-sensitizing agent.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 829. doi:1538-7445.AM2012-829
Abstract 830: Insulin-like growth factor binding protein-2 and chemosensitivity in esophageal adenocarcinoma
Authors: Silvers Amy L. , Lin Lin , Beer David G. , Chang Andrew C.
Published: August 2012

The overall long-term survival for patients with esophageal adenocarcinoma (EAC) remains poor. Despite improved understanding of the progression from Barrett's esophagus to dysplasia to adenocarcinoma, patients commonly present with advanced stage disease and demonstrate resistance to conventional therapy, with response rates below 40%. Understanding the molecular mechanisms of resistance is crucial for predicting and overcoming this resistance. Twenty EAC tissues obtained from patients subsequently treated with chemotherapy were examined using Affymetrix oligonucleotide microarrays. Genes differentially expressed in disease-free patients compared to patients with recurrent disease were identified. One such gene, insulin-like growth factor binding protein-2 (IGFBP-2), is a member of the IGF signaling pathway, which has been shown to play pivotal roles in cell growth, differentiation, survival, transformation, and metastasis. Increased IGFBP-2 expression has been reported in many advanced tumor types and has been previously linked to chemoresistance, making it a promising potential target in EAC. Mean IGFBP-2 levels were significantly higher in patients with recurrent disease and increased expression was associated with worse outcome independent of stage. Of three EAC cell lines examined (Flo-1, OE33, OE19), Flo-1 cells showed the highest IGFBP-2 expression at both the mRNA and protein levels. To examine the role of IGFBP-2 in chemoresistance, Flo-1 cells were pre-treated with siRNA to IGFBP-2 followed by chemotherapy in the presence or absence of serum and analyzed using WST-1 cell proliferation assays. Knocking down IGFBP-2 sensitized Flo-1 cells to cisplatin in the presence of serum and increased proliferation in serum-free conditions, suggesting that IGFBP-2 may be anti-proliferative in this EAC cell line. In addition, treatment of Flo-1 cells with both acute and chronic doses of cisplatin decreased expression of IGFBP-2. Stable transfection of IGFBP-2 into low-level IGFBP-2-expressing OE33 and OE19 cells did not alter cellular proliferation/chemosensitivity, migration, or epithelial-mesenchymal transition as determined by WST-1, wound healing, and Western analyses, respectively, possibly due to amplification of the ErbB2 gene in these cell lines. Although preliminary data suggest that IGFBP-2 may mediate chemoresistance in EAC, its effects may be masked by more potent genetic alterations. Further analysis of the IGF signaling pathway is warranted to determine its significance in the chemoresistance of EAC.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 830. doi:1538-7445.AM2012-830
Abstract 837: Copper efflux transporter-mediated resistance to cisplatin
Authors: Mathews Ryan A. , Safaei Roohangiz , Howell Stephen B.
Published: August 2012

The copper (Cu) efflux transporters ATP7A and ATP7B individually mediate resistance to the Pt-containing chemotherapeutic agents and have been identified as a primary pathway for the sequestration and/or export of these drugs. While the structure and transport function of ATP7A and ATP7B have been well studied, the mechanism by which they mediate resistance to the Pt drugs remains unknown. The experimental system consisted of the human fibroblast cell line Me32a, which does not express either ATP7A or ATP7B, and sublines previously produced by transfection that express either ATP7A (MeMNK) or ATP7B (MeWND). The MeMNK sub-line was 2.2-fold resistant to cisplatin whereas the MeWND cells had a 1.8-fold increase in IC50. The MeMNK and MeWND cell lines also contained a small population of cells that survived lethal dosages of DDP (10 - 20%). The MeMNK and MeWND cells were also 1.6- and 1.9-fold, respectively, resistant to the specific vacuolar proton pump (V-ATPase) inhibitor bafilomycin (Baf). Further investigation revealed that cells expressing ATP7A or ATP7B also had increased expression of V-ATPase subunits A, D and H at the mRNA level that corresponded to 8.6 - 14-fold increases at the protein level indicating that ATP7A and ATP7B perturb the proton transport system that accounts for progressive acidification of vesicles in the secretory pathway. MeMNK and MeWND cells were found to be 34- and 22-fold resistant to brefeldin A (BFA) which reversibly disrupts transport of proteins in the vesicle secretory pathway and specifically targets the ADP-ribosylation factor-1 (Arf1). This led us to investigate the Arf family of proteins and we found that the levels of Arf1, Arf3 and Arf4 were markedly reduced in cells expressing ATP7A and ATP7B at the RNA level; the reduction in Arf1 appears to account for the resistance to BFA and indicates the that function of Arf1 has been taken over by some other protein. Furthermore, we found large perturbations in the level of proteins that constitute the regulatory machinery of the vesicle secretory pathway including guanine nucleotide exchange factors (GEFs) and coat protein complexes in the MeMNK and MeWND cells. These findings indicate that ATP7A and ATP7B both produce quite large perturbations in the expression of proteins whose function is essential to the formation and trafficking of vesicles in the secretory pathway. As ATP7A and ATP7B have previously been shown to be capable of sequestering cisplatin into the microvesicular fraction of the MeMNK and MeWND cells, we conclude that these changes are linked to the ability of these Cu transporters to mediate cisplatin resistance.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 837. doi:1538-7445.AM2012-837
Abstract 839: Chemotherapeutic sensitization of drug-resistant lung cancer cells by doxorubicin and leptomycin B
Authors: Lu Chuanwen
Published: August 2012

The development of novel targeted therapies has become an important research focus for lung cancer treatment. Our previous study has shown leptomycin B (LMB) significantly inhibited proliferation of lung cancer cells; however, p53 wild type lung cancer cells were resistant to LMB. Therefore, the objective of this study was to develop and evaluate a novel therapeutic strategy to sensitize LMB-resistant lung cancer cells by combining LMB and doxorubicin (DOX). Among the different treatment regimens, pre-treatment with DOX (pre-DOX) and subsequent treatment with LMB to A549 cells significantly decreased the 50% inhibitory concentration (IC50) as compared to that of LMB alone (4.4 nM vs. 10.6 nM, P < 0.05). Analysis of cell cycle and apoptosis by flow cytometry further confirmed the cytotoxic data. To investigate molecular mechanisms for this drug combination effects, p53 pathways were analyzed by Western blot, and nuclear proteome was evaluated by two dimensional difference gel electrophoresis (2D-DIGE) and mass spectrometry (MS). In comparison with control groups, the levels of p53, phospho-p53 (ser15), and p21 proteins were significantly increased while phospho-p53 (Thr55) and survivin were significantly decreased after treatments of pre-DOX and LMB (P < 0.05). The 2D-DIGE/MS analysis identified that sequestosome 1 (SQSTM1/p62) had a significant increase in pre-DOX and LMB-treated cells (P < 0.05). In conclusion, our results suggest that drug-resistant lung cancer cells with p53 wild type could be sensitized to cell death by scheduled combination treatment of DOX and LMB through activating and restoring p53 as well as potentially other protein(s)/pathway(s).

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 839. doi:1538-7445.AM2012-839
Abstract 845: In vitro and in vivo pharmacology of SAR125844, a potent and selective intravenous MET kinase inhibitor undergoing Phase I clinical trial
Authors: Goulaouic Hélène , Kenigsberg Mireille , Delaisi Christine , Begassat Françoise , Do-Vale Véronique , Mestadier Jessica , Bonche Fabrice , Bénard Tsiala , Nicolas Jean-Paul , Calvet Loreley , Egile Coumaran , Nemecek Conception , Lengauer Christoph
Published: August 2012

SAR125844 is a potent MET kinase inhibitor for intravenous (IV) administration, with nanomolar activity against the wild-type enzyme (IC50 = 4.2 nM) and some kinase domain mutants, such as M1250T and Y1235D. It is highly selective for MET kinase in a panel of 275 kinases tested, with only 5 other protein kinases inhibited at IC50 values below 300 nM. In cellular assays, SAR125844 inhibits MET autophosphorylation at the nanomolar range (IC50 from 1.4 to 5.1 nM), translating into antiproliferative activity selectively in MET-driven cell lines such as MET-amplified cell lines, with IC50 values in the low nanomolar range and induction of apoptosis. SAR125844 induces a G1 block in the two MET-amplified tumor cell lines tested. Moreover, the compound is also able to inhibit HGF-induced cell migration in PC-3 prostate tumor cell line. In two MET-amplified human gastric tumor xenograft models tested, SNU-5 and Hs 746T, SAR125844 intravenous treatment leads to potent impact on the MET signaling pathway in a dose and time dependent manner, with potent inhibition of MET autophosphorylation, as well as a significant effect on downstream PI3K/AKT and RAS/MAPK pathways. As a single agent, this translates into a dose-dependent antitumor activity in these two xenograft models, with tumor stasis at the lowest active dose and tumor regression at the highly active doses. High loading single dose administration of SAR125844 using a nanosuspension formulation allowed a sustained P-MET inhibition in tumors up to 7 days. In all models, antitumor activity was achieved at well tolerated doses without significant effect on body weight. The observed correlation between P-MET inhibition in the tumor and antitumor activity in preclinical settings suggests that P-MET evaluation in tumor biopsies could be a direct pharmacodynamic biomarker of SAR125844 activity in patients. In order to investigate whether a non-invasive biomarker could also be used as pharmacodynamic read-out, we measured shed-MET (soluble extracellular domain of the MET receptor) in the plasma of tumor-bearing mice and showed that its level correlates with tumor burden in 2 MET-amplified xenograft models.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 845. doi:1538-7445.AM2012-845
Abstract 846: Targeted inhibition of c-Met receptor by a selective c-Met inhibitor, Tivantinib, and a specific shRNA reduces breast cancer-derived bone metastases
Authors: Previdi Sara , Abbadessa Giovanni , Dalò Francesca , France Dennis S. , Broggini Massimo
Published: August 2012

Breast cancer exhibits a propensity to metastasize to bone, resulting in debilitating skeletal-related complications associated with significant morbidity and mortality. Because of the clinical significance of this process, many research efforts are aimed at uncovering the molecular events in bone metastases to identify novel targets and to improve clinical management of metastatic bone disease. The interactions between metastatic cells and bone are critical to the development and progression of bone metastases, and their unravelling could lead to novel preventive or therapeutic approaches. We previously demonstrated the critical role of HGF/c-Met/β-catenin/TCF system in tumor-bone interaction leading to skeletal metastases of human breast cancer cells, suggesting the potential inhibition of this pathway in vivo. In this study, we evaluated the potential therapeutic efficacy of targeting the c-Met receptor by using both an oral, selective, small-molecule c-Met inhibitor, tivantinib, and a specific shRNA against c-Met in an experimental bone metastatic model of human breast cancer. Tivantinib exhibited dose-dependent anti-metastatic activity in vivo, and the 120 mg/kg dose, while being ineffective in reducing subcutaneous tumor growth, induced significant inhibition of bone metastatic growth and a noteworthy reduction of tumor-induced osteolysis. shRNA-mediated c-Met silencing did not affect in vitro proliferation of bone metastatic cells, but strongly reduced their migration, and this effect was further enhanced by tivantinib. These data were confirmed in vivo. Indeed, dual c-Met inhibition with both tivantinib and RNA interference strategy induces pronounced tumor growth suppression with concomitant marked decreases of lytic lesions and an improvement in survival. Overall, our findings highlighted the efficacy of c-Met inhibition in delaying the onset and progression of bone metastases and strongly suggested that targeting the c-Met receptor may have promising therapeutic value in the prevention and treatment of bone metastases from breast cancer. Most importantly, the finding that tivantinib is active as an anti-metastatic agent at low, non-cytotoxic doses suggests that its efficacy may be potentiated by combining it with other therapies that target cancer cell-bone interactions.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 846. doi:1538-7445.AM2012-846
Abstract 848: Preclinical antitumor activity of S 49076, a novel MET / AXL / FGFR kinase inhibitor and molecular stratification for tumor sensitivity
Authors: Burbridge Mike F. , Bossard Celine , Saunier Carine , Fejes Imre , Bruno Alain , Pierre Alain , Guigal-Stephan Nolwen , Rodriguez Marianne , Galizzi Jean-Pierre , Lockhart Brian P. , Jacquet-Bescond Anne , Ortuno Jean-Claude , Cruzalegui Francisco H. , Depil Stephane
Published: August 2012

Aberrant activity of receptor tyrosine kinases (RTKs) has been associated with tumor progression in a wide variety of human malignancies, making them promising drug targets for cancer therapy. Although, in some instances, specific inhibition of just one of these RTKs suffices for inhibition of tumor progression, in the majority of cases, targeting more than one RTK could be required for therapeutic efficacy. Moreover, increased expression or activation of RTKs is often associated with resistance to standard chemotherapy agents or signal transduction modulators. S 49076 is a novel, potent, ATP-competitive tyrosine kinase inhibitor of the RTKs MET, AXL and FGFR. S 49076 blocks autophosphorylation of these RTKs and their downstream signaling in cells with IC50 values of less than 50 nM in the case of MET and AXL, and at below 200 nM for FGFR1/2/3. In vitro, S 49076 inhibits the proliferation of MET- and FGFR2- dependent gastric cancer cells, blocks MET-driven migration of lung carcinoma cells and inhibits colony formation of hepatocarcinoma cells overexpressing FGFR2 and AXL. In vivo, oral administration of S 49076 inhibits MET autophosphorylation and tumor growth in subcutaneous GTL-16 human gastric carcinoma and U87-MG human glioblastoma at 6 mg/kg/day. In FGFR2-dependent SNU-16 gastric tumors S 49076 inhibits FGFR2 autophosphorylation, downstream signaling and tumor growth at 25 mg/kg/day. In a panel of 53 patient-derived tumors and 14 cell lines of diverse origin growing in three-dimensional in vitro culture, twenty-five (37%) were found to be sensitive to S 49076 at 1 µM or less. In the majority of cases, analysis of the expression, activation and mutation status of MET, AXL, FGFR1/2/3 and other target kinases of S 49076 as well as that of major signaling proteins enabled hypotheses to be made concerning the sensitivity or resistance to S 49076. Moreover, in many of these resistant tumors, a rationale for association of S 49076 with other targeted therapies emerged. Examples of the efficacy of such combined therapies will be shown. Based on these preclinical studies showing a favorable and novel pharmacological profile of S 49076, a phase I study is currently underway in patients with advanced solid tumors.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 848. doi:1538-7445.AM2012-848
Abstract 851: Epidermal growth factor receptor inhibitor erlotinib prolongs survival in Kras-mutant pancreatic ductal adenocarcinoma by inhibiting gemcitabine-induced mitogen activated protein kinase signaling activation
Authors: Miyabayashi Koji , Ijichi Hideaki , Mohri Dai , Tada Motohisa , Yamamoto Keisuke , Asaoka Yoshinari , Ikenoue Tsuneo , Nakai Yousuke , Isayama Hiroyuki , Omata Masao , Moses Harold , Koike Kazuhiko
Published: August 2012

Pancreatic ductal adenocarcinoma (PDAC) is one of the most deadly cancers. New therapeutic approaches to improve the prognosis are highly required. We generated pancreas-specific TGF-beta receptor II (Tgfbr2) knockout mice in the context of Kras activation, which recapitulated clinical and histopathological manifestations of human PDAC, indicating that an impact of blockade of TGF-beta signaling in PDAC progression. An EGFR inhibitor erlotinib showed a superior survival effect in combination with gemictabine, however, the mechanism by which PDAC with extremely frequent KRAS-mutation benefits from EGFR inhibition remains largely unkown. Using the model we investigated the anti-tumor impact and mechanisms of erlotinib in combination with gemcitabine. We treated the mice with elrotinib and gemcitabine. Median survival times were 52.5, 69, and 74 days for control, gemcitabine alone, and gemcitabine + erlotinib, respectively. Gemcitabine alone significantly extended the survival compared to the control. Further, adding erlotinib to gemcitabine prolonged the survival significantly compared to gemcitabine alone. Interestingly, treatment with gemcitabine enhanced the activation of MAPK signaling, which was inhibited by adding erlotinib, even in the KRAS-mutant PDAC in vivo and in vitro. We observed that the gemcitabine-induced MAPK signaling activation was due to induction of EGFR ligands expression and also due to ERBB2 activation in PDAC cells. Erlotinib inhibited the ERBB2 activation, partly by inhibiting heterodimer formation with EGFR and also decreasing ERBB2 protein expression in PDAC cells. This mouse model appears recapitulating chemosensitivity of human PDAC and indicates the significance of ERBBs in PDAC treatment. This model also might provide important insights into the beneficial patient subpopulation and the mechanism of the action of drugs and chemoresistance, in which TGF-beta signaling might be highly involved.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 851. doi:1538-7445.AM2012-851
Abstract 860: The multi-targeted kinase inhibitor Sunitinib induces apoptosis in colon cancer cells via PUMA
Authors: Sun Jing , Sun Quanhong , Brown Matthew F. , Dudgeon Crissy , Chandler Julie , Zhang Lin , Yu Jian
Published: August 2012

Key words: Sunitinib; PUMA; FoxO3a; Bcl-2 family; colon cancer Purpose: Sunitinib is a FDA approved multi-targeted receptor tyrosine kinase (RTK) inhibitor for treating solid tumors. Inhibition of angiogenesis, immune modulation and induction of apoptosis has been suggested to mediate the anti-tumor effects of sunitinib. However, its cell killing mechanisms are not well-understood. In this study, we investigated the mechanisms and significance of sunitinib-mediated apoptosis in its antitumor activities using colon cancer cells and xenografts. Experimental Design: The expression of various Bcl-2 family proteins, apoptosis and long-term growth in response to sunitinib were examined in colon cancer cells. The mechanism of PUMA induction and effects of PUMA deficiency, BH3 mimetics and 5-FU on sunitinib-induced apoptosis were investigated. The effects of PUMA deficiency in responses to sunitinib were determined in xenografts. Results: We found that consistent PUMA induction mediated by transcription factor FoxO3a plays an important role in the apoptosis induced by sunitinib. PUMA deficiency led to impaired apoptosis and caspase activation in colon cancer cells with either wildtype or mutant p53. Small molecule BH3 mimetics or elevated PUMA levels sensitized colon cancer cells to sunitinib-induced apoptosis. PUMA deficiency significantly blocked apoptosis and therapeutic responses to sunitinib in xenografts. Conclusions: Our results establish a critical role of PUMA in mediating sunitinib sensitivity in colon cancer cells and lack of apoptosis induction as a potential resistance mechanism. Our study suggests modulations of Bcl-2 family proteins as potential biomarkers, and combination of sunitinib with BH3 mimetics or chemotherapeutic agents might improve the treatment efficacy in colon cancer patients.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 860. doi:1538-7445.AM2012-860
Abstract 875: Marked in vivo efficacy of combined BCLXL and MEK inhibition in KRAS mutant cancers revealed by a pooled shRNA-drug screen for genes that are “synthetically lethal” with MEK inhibitors
Authors: Corcoran Ryan B. , Cheng Katherine A. , Wong Kwok-Kin , Engelman Jeffrey A.
Published: August 2012

Although KRAS is the most commonly mutated oncogene in human cancer, no effective therapies exist for KRAS mutant cancers. Attempts to target KRAS directly or to target single effector pathways downstream of KRAS have met limited success. Previously, our laboratory and others showed that simultaneous targeting of more than one KRAS effector pathway, specifically the MEK-ERK and PI3K-AKT pathways, can cause dramatic responses in KRAS-driven genetically-engineered mouse tumor models. These findings support the promise of targeted therapy combinations for KRAS mutant cancers and have led to clinical trials evaluating combined PI3K/MEK inhibition. We evaluated the efficacy of combined PI3K/MEK inhibition in a panel of 30 KRAS mutant cell lines. Roughly half of all cell lines showed limited sensitivity to this combination, suggesting that combined PI3K/MEK inhibition may only be effective in a subset of KRAS mutant cancers and underscoring the need for additional combination therapy strategies. To develop new targeted therapy combinations for KRAS mutant cancers, we designed a pooled shRNA-drug screen strategy aimed at rapidly identifying genes that, when inhibited, synergize with MEK inhibitors to decrease the viability of KRAS mutant cancer cells. Using this approach, we identified the anti-apoptotic protein BCLXL as a potential target for combination therapy with MEK inhibitors. When tested in vitro against a panel of 30 KRAS mutant cell lines, simultaneous pharmacologic inhibition of BCLXL (using the BH3 mimetic ABT-263) and MEK led to pronounced apoptosis and reduced viability in most cell lines, including many cell lines that were insensitive to combined PI3K/MEK inhibition. In vivo, the combination of ABT-263 and a MEK inhibitor led to marked tumor regressions in KRAS mutant xenograft models and to dramatic and sustained tumor regressions (>70% reduction in tumor size) in a KRAS-driven genetically-engineered mouse model of lung cancer. These findings suggest that combined inhibition of BCLXL and MEK is a promising targeted therapy combination for potential evaluation in clinical trials for patients with KRAS mutant cancers.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 875. doi:1538-7445.AM2012-875
Abstract 880: Inhibition of MMP14 potentiates the antiglioma effect of TMZ and ionizing radiation
Authors: Ulasov Ilya , Auffinger Brenda , Thaçi Bart , Pytel Peter , Kaverina Natalya , Liu Feifei , Ahmed Atique , Lesniak Maciej
Published: August 2012

Introduction. Glioblastoma multiforme (GBM) is the most common primary central nervous system tumor in adults. The median survival after surgical intervention alone is approximately 6 months and the addition of radiation and chemotherapy (like Temozolomide, TMZ) can only extend this up to 14.6 months. Other treatment options are therefore needed for better disease management and improved survival. We ran an Affymetrix analysis on the Rembrandt Database to determine the role of metalloproteinase expression in the biology of GBMs. High expression of MT1-MMP (MMP14) correlated with a poor patient survival. MMP14, as other metalloproteinases, is a cellular based proteolytic endopeptidase that plays a role in extracellular matrix (ECM) and basic membrane (BM) degradation. In glioma, expression of MMP14 is correlated with tumor invasiveness and associated with the CD133+ phenotype. Inhibition of MMP14 could therefore offer a potential target for the therapy of GBM. Experimental methods. Expression of MMP14 was determined in 100 primary and recurrent gliomas by immunohistochemistry. We performed quantitative RT-PCR and Western blotting analysis of MMP14 expression to investigate the effect of radiation and TMZ on U87 and U251 glioma cells. We used the Ingenuity Software to analyze the relationship between MMP14 and proteins responsible for angiogenesis and cell proliferation. Anti-angiogenic effect of MMP14 knockdown was determined by tube formation assay and angiogenic cytokine array (RayBio). Finally, treatment of MMP14 knockdown of glioma cells with temozolomide and ionizing radiation was analyzed by MTT assay. Results. Genetic silencing of MMP14 leads to inhibition of glioma cell proliferation and cell cycle arrest. We also show that silencing of MMP14 results in downregulation of angiogenic markers at the mRNA and protein level. Furthermore, we have found that inhibition of MMP14 expression in glioma cells improves the therapeutic effect of temozolomide and ionizing radiation. Conclusions. This study suggests that silencing of MMP14 via RNAi technology improves therapeutic effect of TMZ and ionizing radiation on glioma cell proliferation. Therefore, inhibition of MMP14 provides a new target for treatment of gliomas.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 880. doi:1538-7445.AM2012-880
Abstract 883: Cell-based selection of RNA-aptamers to specifically target glioblastoma cancer stem cells
Authors: Quintavalle Cristina , Ricci-Vitiani Lucia , Esposito Carla Lucia , Martino Simona Di , Cerchia Laura , Maria Ruggero De , de Franciscis Vittorio , Condorelli Gerolama
Published: August 2012

Stem cells are a group of cells, which have two important fundamental properties: self-renewal and multipotency. Stem cells have been identified also in many human cancers on the basis of being both morphologically and functionally distinct from other cells within the heterogeneous tumor mass. According to “cancer stem cell hypothesis,” the cancer stem cells (CSC) would remain unaffected by conventional therapies, and capable of repopulating the tumor and giving rise to cancer recurrence. The possibility to identify highly selective biomarkers on CSC would greatly improve cancer diagnosis and treatment. Recently, nucleic acid-based aptamers have proven useful as reagents for identifying cell surface proteins and for cell typing. Further, their high specificity and low toxicity render them a valid alternative to antibodies for in vivo cell recognition. We have developed the SELEX technology on intact glioblastoma cancer stem cells to generate aptamers as biologically active high affinity ligands for CSC-specific cell surface proteins. The approach has been applied by utilizing glioblastoma differentiated tumor cells as a negative selection, and cancer stem cells obtained from two different patients, as positive selection. Upon 16 cycles of SELEX, we generated a set of 2′-fluoro-pyrimidines containing RNA aptamers that, based on sequence analysis, have been grouped into 5 main families. Best aptamers have been then selected by binding experiments for their ability to distinguish glioblastoma CSC from differentiated tumor cells. We thus determined the binding affinity of each molecule to the cell surface specific targets. Functional experiments will be as well presented to further insight the biological role of the most promising aptamer molecules in the acquisition and maintenance of stem cells properties of glioma cancer cells. Results demonstrate the possibility to generate RNA-based aptamers as potential innovative tools for the selective targeting of cancer stem cells. A proteomic approach will define the specific membrane targets of the selected aptamers

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 883. doi:1538-7445.AM2012-883
Abstract 887: Development of a robust nanoimmunoassay and immunohistochemical assay for asparagine synthetase
Authors: Lorenzi Philip L. , Heathcock Lindsey E. , Aldape Kenneth , Weinstein John N.
Published: August 2012

The enzyme-drug L-asparaginase (L-ASP) has been used for four decades to treat acute lymphoblastic leukemia. However, its unique mechanism of action is still poorly understood, and its clinical efficacy has proven unpredictable. Those problems have prompted a continuing search for biomarkers that predict L-ASP response. We previously found that the expression of asparagine synthetase (ASNS) is strongly negatively correlated with L-ASP anticancer activity in ovarian cancer cell lines, suggesting that L-ASP might be effective against a low-ASNS subset of ovarian cancers if salient characteristics of the cell lines reflect clinical ovarian tumors. However, quantitatively robust, single-antibody assays for ASNS expression have been absent from the literature. We therefore used a capillary-based isoelectric focusing (IEF) platform (the NanoPro 1000) to screen twelve ASNS antibodies for their specificity and sensitivity. Only two antibodies exhibited completely on-target activity (as shown by signal ablation by ASNS siRNA) and sufficient sensitivity. The on-target activity corresponded to a single band on Western Blot and a single peak on the NanoPro 1000, suggesting the existence of just one ASNS protein isoform. Optimized, final NanoPro assay conditions yielded less than 8% CV, a 160-fold dynamic range, and Zα-factor of 0.82, indicating a robust assay that is amenable to high-throughput screening. We next used the best ASNS antibody to develop an immunohistochemistry (IHC) assay for ASNS. As with the NanoPro assay, optimized IHC conditions yielded a large dynamic range of staining intensity, and staining was completely ablated by ASNS siRNA. To test the hypothesis that subsets of various cancers express very low levels of ASNS, we have initiated ASNS IHC of more than 20 tissue arrays representing a wide variety of cancers. Using a 3-point scoring system (0 = negative, 1 = low, 2 = high), preliminary results indicate that 90/136 (66%) of bladder cancers, 29/60 (48%) of bone cancers, 16/76 (21%) of breast cancers, 29/115 (25%) of brain cancers, 51/168 (30%) of colon cancers, and 7/64 (11%) of head and neck cancers are ASNS-negative (score = 0), suggesting that a subset of each cancer type might be sensitive to the drug L-asparaginase. Efforts are underway to apply the NanoPro assay to the NCI-60 cell line panel and to continue performing ASNS IHC to survey tissue arrays for ASNS expression.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 887. doi:1538-7445.AM2012-887
Abstract 89: Osteopontin-c and osteopontin-b splicing isoforms activate prostate cancer progression features
Authors: Tilli Tatiana M. , Mello Kivvi Duarte De , Accioly Maria Theresa , Faria Paulo Antonio , Gimba Etel Rp
Published: August 2012

Osteopontin (OPN) is one of the proteins overexpressed in prostate cancer (PCa) and is involved in tumorigenesis and metastasis. Alternative splicing of the OPN gene generates three protein splicing isoforms (OPN-SI), designated as OPNa, OPNb and OPNc, which have demonstrated specific roles in different tumor models. However, the roles of each of these isoforms have not been previously characterized in PCa. Our previous study reported that OPN-SI were overexpressed in PCa tissues, strongly associated with PCa occurrence and with tumor cell differentiation. Besides, OPNc was the most upregulated variant. We have also demonstrated that OPNc splicing isoform can contribute for PCa diagnosis and prognosis. Based on these results, the present study aimed to evaluate the putative roles of OPN-SI in PCa biology using in vitro and in vivo functional assays. PC-3 was stably transfected with expression vectors containing OPNa, OPNb and OPNc, as well as empty vector control. PC-3 cells overexpressing each construct were analyzed for in vivo tumor growth and in relation to different aspects mimicking tumor progression, such as cell proliferation, migration, invasion and soft agar colony formation. OPNc and OPNb overexpressing cells significantly activated enhanced xenograft tumor growth and PC-3 proliferation, migration, invasion, and soft agar colony formation, as well as the expression of several cancer related genes. Additionally, we have also shown that some of the OPNc and OPNb-dependent pro-tumorigenic roles are mediated by PI3K/Akt signaling pathway. Inhibition of this pathway by using LY294002 specifically inhibited tumor progression features evoked by OPNc and OPNb overexpression. According to our data, OPNc and OPNb roles on favoring different aspects of PCa progression suggest that these isoforms contribute to the physiopathology of prostate cancer progression and tumorigenesis. Altogether, the data open possibilities of new therapeutic approaches for prostate cancer that selectively downregulate OPNc and OPNb, altering its properties favoring prostate tumor progression.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 89. doi:1538-7445.AM2012-89
Abstract 890: Interleukin 11: A novel therapeutic target in IL-11Rα expressing sarcomas
Authors: Mancini Monica , Fer Nicole , Perez Victor , Teicher Beverly , Rapisarda Annamaria
Published: August 2012

Interleukin-11 (IL-11) is a member of the IL-6 cytokine family, which mediate signaling via a common signal-transducing gp130 component and a cytokine-specific subunit (IL-11Rβ). Upon binding to the IL-11Rα, a signaling cascade activates several pathways, including JAK kinases, STAT transcription factors (STAT3 and STAT1), MAPK, src-family kinases and PI3K. IL-11 has been implicated in experimental models of chronic inflammation and associated tumorigenesis. Oncomine analysis of publicly available microarray data from patient biopsies showed that IL-11Rα mRNA is expressed in several sarcomas and not in the matched normal tissue counterparts. Surgical resection and cytotoxic chemotherapy are the standard of care for most locally advanced and metastatic sarcomas, the identification of new markers and the development of targeted therapies are needed to increase long-term survival of these patients. Previous studies demonstrated IL-11Rα is expressed in human primary and metastatic osteosarcomas but not in normal bone, suggesting that IL-11Rα is a potential target for sarcoma therapy. We analyzed a panel of 45 human sarcoma cell lines for the expression of IL-11Rα and IL-11. Interestingly, IL-11Rα protein is expressed at high levels in the majority of cell lines examined. In addition, we found that nearly all osteosarcoma, rhabdomyosarcoma, fibrosarcoma and Ewing sarcoma cell lines express high constitutive levels of IL-11 mRNA, indicating that IL-11 autocrine signaling may play a role in these tumor types. Two lentiviral vectors, used for the delivery of shRNA targeting IL-11 in HT-1080, produced an 80-90% decrease in IL-11 mRNA expression when compared to the luciferase control shRNA; however, IL-11 mRNA levels remained significantly high in HT1080 knock-down cells when compared to the constitutive levels of non sarcoma cancer types. Decreasing levels of IL-11 in HT-1080 resulted in a 50% inhibition of cell growth, demonstrating that IL-11 has a role in cell proliferation. Further experiments aimed to assess the expression of IL-11 and IL-11Rβ in xenografts and to explore the role of IL-11 in sarcoma pathogenesis, propagation and response to therapy are ongoing. These data suggest that neutralization of IL-11 or IL-11Rα may be a potential target for the development of cancer therapeutics for sarcomas. Funded by NCI Contract No. HHSN261200800001E.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 890. doi:1538-7445.AM2012-890