bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract 1686: Synergistic combination of Trabectedin and Olaparib in breast cancer tumor cell lines
Authors: Avila Sonia , Martínez Marta , Moneo Victoria , Martínez-Leal Juan F. , Cuevas Carmen , Garcia-Fernández Luis F. , Galamarini Carlos M.
Published: May 2015

Trabectedin (Yondelis, ET-743) is a marine-derived antitumor agent that is currently used for the treatment of sarcoma and, in combination with pegylated-liposomal doxorubicin, of platinum-sensitive ovarian cancer patients. After binding to the DNA minor groove, trabectedin induces a potent transcription inhibition on tumor cells and tumor-associated macrophages. The resolution of functional DNA adducts generated by the drug is known to occur through the coordinated action of multiple DNA repair pathways, including homologous recombination (HR), a process that gives rise to double-strand breaks (DSBs). Trabectedin treatment at nanomolar concentrations does indeed produce a high proportion of DSB-positive tumor cells with abundant γ-H2AX foci and an S-phase delay/arrest by activation of the DNA replication checkpoints. We had previously shown the synergism (CI < 1) of the combination of Trabectedin with Olaparib (AZD-2281) in the breast cancer cell lines HCC-1937, MCF-7, MDA-MB-231 and MDA-MB-436. In this work we have investigated the mechanism of this synergistic effect at the molecular level. While the treatment with either compound alone (0.05 nM Trabectedin or 5 μM Olaparib for 72 hours) induced only a mild antiproliferative effect, the combination of both compounds at the mentioned concentrations induced strong apoptosis in all the breast cancer cell lines. Exposure to 0.5 and 2.5 nM Trabectedin for 72 hours induced a clear accumulation of γ-H2AX foci. Exposure to Olaparib alone induced only a mild DNA damage at 72 hours with all the concentrations tested. Olaparib induced a clear inhibition of PARylation at concentrations from 1-2.5 μM of the compound. The combination of both drugs, keeping Olaparib at 5 μM and varying the concentrations of Trabectedin from 0.05 to 2.5 nM, demonstrated a synergistic effect on the accumulation of histone H2AX phosphorylation, as analyzed both by western blotting and immunofluorescence microscopy. When comparing all these results, it was clearly seen that, although Trabectedin or Olaparib generated a considerable amount of DSBs, the combination of both drugs induced a higher proportion of DNA damage that remained at very high levels even after 72 hours of treatment. Thus, the observed synergistic effect seems to be the result of higher accumulation of DSBs after the administration of the combination of Trabectedin with Olaparib.

Citation Format: Sonia Avila, Marta Martínez, Victoria Moneo, Juan F. Martínez-Leal, Carmen Cuevas, Luis F. Garcia-Fernández, Carlos M. Galamarini. Synergistic combination of Trabectedin and Olaparib in breast cancer tumor cell lines. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1686. doi:10.1158/1538-7445.AM2014-1686
Abstract 1687: A BRCA2-targeting antisense oligodeoxynucleotide enhances cisplatin effectiveness by decreasing human tumor cell proliferation, metastatic frequency, and metabolic response
Authors: Rytelewski Mateusz , Tong Jessica , Buensuceso Adrian , Leong Hon , Ferguson Peter , Vareki Saman Maleki , Cresce Christine Di , Romanow Larissa , Shepherd Trevor , Deroo Bonnie , Chambers Ann , Vincent Mark , Koropatnick James
Published: May 2015

BRCA2 is involved in homologous recombination repair of double-stranded DNA breaks in human cells. Inactivating mutations in BRCA2 predispose to early onset cancer of the breast, ovary and other tissues. However, patients with tumors that harbor BRCA2 mutations respond better to cancer therapy. Therefore, reducing BRCA2 in cancer cells capable of homologous recombination repair may sensitize otherwise resistant tumors to DNA-damaging anti-cancer treatment. We developed a second generation antisense oligodeoxynucleotide (BR-1) that specifically targets BRCA2. BR-1 decreased BRCA2 mRNA and protein and inhibited BRCA2-mediated RAD51 repair focus formation. BR-1 potently sensitized A549 (lung), SKOV-3 (ovarian), and MDA-MB-231 (breast) cells to cisplatin as evidenced by decreased cell proliferation. However, non-cancerous HK-2 kidney cells were not sensitized to cisplatin by BR-1. In A549 cells BR-1 enhanced cisplatin or ionizing radiation-induced inhibition of in vitro colony formation. Cisplatin-resistant head and neck squamous cancer cells (HN-15a) were rendered as sensitive to cisplatin following BR-1 treatment as the parent population. In addition, BR-1 plus cisplatin treatment decreased A549 cell metastatic frequency in an in vivo chicken chorio-allantoic membrane (CAM) model by over 70% when compared with drug treatment alone. Treatment with BR-1 and cisplatin decreased cellular respiration (decreased oxygen consumption) compared to control oligonucleotide plus cisplatin treatment, suggesting that downregulation of BRCA2 in the context of platinating drug treatment alters cellular metabolism. This change in respiration occurred independently of changes in mitochondrial number. We are continuing to develop and test BR-1 with the aim of applying it in an adjuvant setting with cisplatin in human clinical trials in the future. Supported by grants from the Ontario Centres of Excellence (OCE)

Citation Format: Mateusz Rytelewski, Jessica Tong, Adrian Buensuceso, Hon Leong, Peter Ferguson, Saman Maleki Vareki, Christine Di Cresce, Larissa Romanow, Trevor Shepherd, Bonnie Deroo, Ann Chambers, Mark Vincent, James Koropatnick. A BRCA2-targeting antisense oligodeoxynucleotide enhances cisplatin effectiveness by decreasing human tumor cell proliferation, metastatic frequency, and metabolic response. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1687. doi:10.1158/1538-7445.AM2014-1687
Abstract 1692: Dalantercept, an ALK1 inhibitor of angiogenesis, in combination with cisplatin inhibits tumor growth in a xenograft model of squamous cell carcinoma of the head and neck
Authors: Alimzhanov Marat , Lee Michael , Solban Nicolas , Pearsall Scott , Pandya Susan , Sherman Matthew L. , Kumar Ravindra
Published: May 2015

Activin receptor-like kinase 1 (ALK1) is a key regulator of angiogenesis and vascular morphogenesis. ALK1 and its co-receptor endoglin are selectively expressed on the surface of activated endothelial cells during angiogenesis. Bone morphogenetic proteins (BMP) 9 and 10 are ligands that bind to ALK1 and induce activation of the heteromeric receptor complex, phosphorylation of SMAD1/5/8, and upregulation of specific genes involved in the maturation stage of angiogenesis, such as Id-1 and TMEM100. In particular, BMP9 expression is upregulated in a majority of squamous cell carcinomas of the head and neck (SCCHN).

Dalantercept is an ALK1 extracellular domain-Fc fusion protein that binds BMP9 and BMP10 with high affinity and antagonizes ALK1 signaling in vivo resulting in defective vascular maturation and inhibition of tumor growth in preclinical models. In a completed Phase 1 trial in patients with advanced, refractory solid tumors dalantercept demonstrated signs of clinical activity in a variety of patients, including two of three patients with SCCHN who achieved either an objective response or prolonged stable disease. A Phase 2 trial of dalantercept as monotherapy in recurrent/metastatic SCCHN patients who have had prior platinum-based chemotherapy is currently ongoing.

Based upon the single agent activity of both dalantercept and cisplatin in SCCHN, we tested the feasibility of the combination of cisplatin plus dalantercept in a mouse model of SCCHN. Combination treatment of dalantercept plus cisplatin showed significant tumor growth inhibition (TGI) in the RPMI2650 xenograft model (59% TGI on day 30) which was significantly better than either cisplatin (35% TGI, p= 0.0077) or dalantercept (32% TGI, p=0.0002) alone. No additional toxicity was observed in the combination treatment group compared to cisplatin monotherapy group.

These data suggest that combination of dalantercept plus cisplatin may result in enhanced clinical activity and supports prospective evaluation in patients with SCCHN.

Citation Format: Marat Alimzhanov, Michael Lee, Nicolas Solban, Scott Pearsall, Susan Pandya, Matthew L. Sherman, Ravindra Kumar. Dalantercept, an ALK1 inhibitor of angiogenesis, in combination with cisplatin inhibits tumor growth in a xenograft model of squamous cell carcinoma of the head and neck. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1692. doi:10.1158/1538-7445.AM2014-1692
Abstract 1695: CKD-581, a novel histone deacetylase inhibitor, synergistically enhances Bortezomib cytotoxicity in multiple myeloma cells
Authors: Lee Chansu , Ahn Kwang-Sung , Jung Woo June , Koh Youngil , Kim Hyo Jung , Lee Hyun Jung , Yoon Hwi-Joong , Yoon Sung-Soo
Published: May 2015

For Multiple Myeloma (MM), better anti-MM therapies need to be developed in order to treat refractory, relapsed, and newly diagnosed MM. Recently, Histone deacetylase inhibitors (HDACIs) as a combined drug with bortezomib have been evaluated for the treatment of MM. In this study, we examined to determine the anti-MM effects of a novel HDACI, CKD-581, in MM cells. We treated MM cells with CKD-581 either alone or in combination with Bortezomib. Treatments of 9 different MM cell lines with CKD-581 resulted in dose-and time-dependent growth arrest accompanied by the induction of p21 expression and the reduction of cMYC. CKD-581 enhanced Bortezomib-induced cell growth arrest and apoptosis by further reduction of NF-kB mediated cell signaling pathway, which resulted in functional blockage of ubiquitination-related genes. CKD-581, alone or combined with bortezomib, also abrogated the G2/M cell cycle checkpoint, potentially through the suppression of CHK1 expression as well as synergic growth arrest via induction/reduction of CHKs and cMYC, as revealed in combined treatment of CDK-581 and bortezomib. CKD-581-induced sensitization of Bortezomib resistant MM cells to cytotoxic treatment resulted in an increased number of apoptotic cells as judged by annexin V-positivity and the presence of cleaved caspase-3. In addition, CKD-581 effectively induced the apoptosis of MM cells, which were co-cultured with BMSCs obtained from MM patients' BM. CKD-581 effectively inhibited the secretion of IL-6/sIL-6 and HGF, involved in bone lesion, from MM patients' BMSCs. In animal model, CKD-581 was well tolerated, and resulted in tumor growth inhibition and prolonged survival. In summary, the HDAC inhibitor, CKD-581, is a promising therapeutic agent for MM patients, especially when used in combination with Bortezomib.

Citation Format: Chansu Lee, Kwang-Sung Ahn, Woo June Jung, Youngil Koh, Hyo Jung Kim, Hyun Jung Lee, Hwi-Joong Yoon, Sung-Soo Yoon. CKD-581, a novel histone deacetylase inhibitor, synergistically enhances Bortezomib cytotoxicity in multiple myeloma cells. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1695. doi:10.1158/1538-7445.AM2014-1695
Abstract 170: Exosomes derived from mesenchymal stem cells suppress angiogenesis by down-regulating VEGF expression in breast cancer cells
Authors: Park Sae-Ra
Published: May 2015

Exosomes are small membrane vesicles released by a variety of cell types. Exosomes contain genetic materials, such as mRNAs and microRNAs (miRNAs), implying that they may play a pivotal role in cell-to-cell communication. Mesenchymal stem cells (MSCs), which potentially differentiate into multiple cell types, can migrate to the tumor sites and have been reported to exert complex effects on tumor progression. To elucidate the role of MSCs within the tumor microenvironment, previous studies have suggested various mechanisms such as immune modulation and secreted factors of MSCs. However, the paracrine effects of MSC-derived exosomes on the tumor microenvironment remain to be explored. The hypothesis of this study was that MSC-derived exosomes might reprogram tumor behavior by transferring their molecular contents. To test this hypothesis, exosomes from MSCs were isolated and characterized. MSC-derived exosomes exhibited different protein and RNA profiles compared with their donor cells and these vesicles could be internalized by breast cancer cells. The results demonstrated that MSC-derived exosomes significantly down-regulated the expression of vascular endothelial growth factor (VEGF) in tumor cells, which lead to inhibition of angiogenesis in vitro and in vivo. Additionally, miR-16, a miRNA known to target VEGF, was enriched in MSC-derived exosomes and it was partially responsible for the anti-angiogenic effect of MSC-derived exosomes. The collective results suggest that MSC-derived exosomes may serve as a significant mediator of cell-to-cell communication within the tumor microenvironment and suppress angiogenesis by transferring anti-angiogenic molecules.

Citation Format: Sae-Ra Park. Exosomes derived from mesenchymal stem cells suppress angiogenesis by down-regulating VEGF expression in breast cancer cells. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 170. doi:10.1158/1538-7445.AM2014-170
Abstract 1712: Sunitinib-resistant ccRCC cell lines subjected to TKI/mTOR inhibitors as a model for sequence therapy
Authors: Unteregger Gerhard , Schendel Darja , Heinzelmann Joana , Weiland Anne , Ernst Simone , Stoeckle Michael , Junker Kerstin
Published: May 2015

Introduction: Treatment of advanced renal cell carcinoma (RCC) by tyrosine kinase inhibitors like Sunitinib (SUN) is hampered by the appearance of drug resistance. Sequence therapy using different TKIs as well as inhibitors attacking the mTOR pathway offers a promising tool to overcome this lack in ccRCC therapy.

Material and Methods: CAKI-1/2, A-498 and 786-O cell lines were treated with different SUN-concentrations to obtain the corresponding IC50-values. Using sub-lethal SUNI-concentrations they were cultivated for up to 20 passages. At defined intervals total RNA was isolated. Microarray analysis was performed for a global miRNA expression profiling, SUN-resistant cell lines were subjected to an ongoing sequence therapy using TKI 258 (Novartis) and RAD001 as a mTOR inhibitor. Resistance-development as well as drug efficacy during sequence therapy was monitored by sequential quantification of the growth behavior and changes in drug-sensitivity by proliferation-assays.

Results: Growth behavior of all ccRCC cell lines during SUN-application is reduced down to 10-60% depending on cell number and cell type. Long term application (10-20 passages) of SUN at concentrations near the IC50 value results in a constantly increasing drug resistance and the cells acquire a growth rate of 60-90% compared to the untreated long term control. Accordingly to these phenomenon we observed characteristic changes in miRNA expression. Starting sequence therapy SUN-resistant cell lines (CAKI-1 and 786-0) offer initially an increase in drug resistance to TKI 258 in pretreated CAKI-1 cells. In contrast long term SUN-application had no influence in the sensitivity to RAD001 as compared to untreated controls in both cell lines.

Conclusion: Understanding the molecular changes during drug resistance in ccRCC provides an indispensable prerequisite to create new therapeutic strategies in the treatment of metastatic renal cell carcinoma. The results indicate a complex mechanism in drug resistance depending on therapeutic protocol and cell type. However, drug-resistant cell lines offer a promising tool to elucidate the molecular mechanism responsible for drug-resistance as well as to simulate the benefit of a sequence therapy. Since miRNAs represent an important tool in gene regulation the observed patterns may help to elucidate new genes involved in drug resistance in ccRCC.

Citation Format: Gerhard Unteregger, Darja Schendel, Joana Heinzelmann, Anne Weiland, Simone Ernst, Michael Stoeckle, Kerstin Junker. Sunitinib-resistant ccRCC cell lines subjected to TKI/mTOR inhibitors as a model for sequence therapy. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1712. doi:10.1158/1538-7445.AM2014-1712
Abstract 1713: PDK1 and hexokinase 2 are downstream effectors of PTEN loss and regulate response to targeted therapies in multiple tumor types
Authors: Pazarentzos Evangelos , Bivona Trever G.
Published: May 2015

Recent advances in molecular profiling of many human tumor types has enabled the development and clinical use of molecularly-targeted therapies in patients. Many tumors exhibit inactivation of PTEN which is predicted to sensitize tumor cells to PI3 kinase or AKT inhibitor therapy. However, clinical responses to PI3 kinase or AKT inhibitors are variable and not curative. Furthermore, these responses in patients do not correlate uniformly with PTEN inactivation. Therefore, we investigated whether PTEN inactivation could lead to dependence on signaling pathways and components that function independently of PI3K or AKT and that could serve as novel therapeutic targets in PTEN deficient tumors. Using multiple human tumor models including lung adenocarcinoma, lung squamous, renal cell carcinoma, and prostate adenocarcinoma that express or lack PTEN and Gene Set Enrichment Analysis, we identified alterations in numerous metabolic regulatory genes in response to PTEN inactivation, including hexokinase 2 (HK2) and pyruvate dehydrogenase kinase 1 (PDK1). We found that in PTEN-deficient tumor cells HK2 is upregulated and selectively localizes to the mitochondria, where it enhances glycolytic flux and inhibits apoptosis. Furthermore, we found that PDK1 is also upregulated upon PTEN inactivation and suppresses oxidative phosphorylation, upregulating glycolysis and the production of lactate. Thus, we uncovered a novel role for HK2 and PDK1 in the metabolic reprogramming that occurs as a consequence of PTEN inactivation in tumor cells. Furthermore, we found that overexpression of either HK2 or PDK1 confers resistance to targeted therapies against PI3K and other oncogenic drivers more broadly. Conversely, genetic or pharmacological suppression of HK2 or PDK1 enhances response to targeted therapy in multiple tumor cell types. Together, our data identify HK2 and PDK1 as novel molecular biomarkers and promising therapeutic targets in multiple PTEN deficient tumor types.

Citation Format: Evangelos Pazarentzos, Trever G. Bivona. PDK1 and hexokinase 2 are downstream effectors of PTEN loss and regulate response to targeted therapies in multiple tumor types. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1713. doi:10.1158/1538-7445.AM2014-1713
Abstract 1714: Erk inhibitor overcomes type II interleukin 1 receptor, a decoy receptor, associated Regorafenib resistance in colorectal carcinoma
Authors: Mar Ai-Chung , Chu Chun-Ho , Lee Te-Chang
Published: May 2015

We have previously demonstrated that type II interleukin 1 receptor (IL1R2), which is an IL-1 decoy receptor and inhibits exogenous IL-1 signaling, activates the expression of several proinflammatory cytokines. We also found that enhanced expression of IL1R2 promotes tumor growth and increases tumor angiogenesis through activated IL-6/VEGF-A signalings. Recently, we observed a close association of enhanced expression of IL1R2 and Regorafenib resistance in colorectal cancer (CRC) cell lines. Regorafenib is the newly approved multi-kinase inhibitor used for treatment of late-stage metastatic CRC by US FDA. To have a better use of Regorafenib against CRC, we conducted experiments to understand the mechanism underlying which IL1R2 is involved in Regorafenib resistance. In the present study, we demonstrated that silencing of IL1R2 in HT29 cell overcame its resistance to Regorafenib whereas ectopic expression of IL1R2 decreased the sensitivity of HCT116 cell to Regorafenib in in vitro and in vivo systems. IL1R2 silencing also enhanced the apoptotic proteins expression in Regorafenib-treated cells. In addition, we have established Regorafenib-resistant DLD-1 colon cancer cells by growing them in the presence of Regorafenib. Consistently, higher IL1R2 expression was found in Regorafenib-resistant cells than the parental cells. Mechanistically, we observed that Regorafenib treatment significantly resulted in enhanced expression of extracellular-signal-regulated kinase (Erk), which functions as a survival factor, in IL1R2-overexpressing cells. Therefore, pretreatment of IL1R2-overepressing CRC cells with Erk inhibitor, U0126, reversed their Regorafenib resistance, suggesting that Erk signaling cascade is crucial in Regorafenib resistance resulted from IL1R2 overexpression. Taken together, our present study suggested that combination of Regorafenib and Erk inhibitor is a rationale regime to overcome IL1R2 overexpression-induced Regorafenib resistance in CRC patients, but also IL1R2 is a potential biomarker for colon cancer therapy.

Citation Format: Ai-Chung Mar, Chun-Ho Chu, Te-Chang Lee. Erk inhibitor overcomes type II interleukin 1 receptor, a decoy receptor, associated Regorafenib resistance in colorectal carcinoma. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1714. doi:10.1158/1538-7445.AM2014-1714
Abstract 1715: Elucidating mechanisms of resistance to FGFR inhibitors in endometrial cancer
Authors: Packer Leisl M. , Byron Sara , Loch David , Dehkhoda Farhad , Wortmann Andreas , Geng Xinyan , Nones Katia , Grimmond Sean , Pearson John , Waddell Nic , Pollock Pamela
Published: May 2015

Preclinical studies by our lab and others have demonstrated Fibroblast Growth Factor Receptor (FGFR) inhibition is a viable therapeutic strategy in FGFR2-mutant endometrial cancer (EC). A significant clinical issue that we aim to address is that of intrinsic and acquired resistance to anti-FGFR therapeutics in the context of EC.

Using mutagenesis screens, we have identified mutations in the FGFR2 kinase domain that cause resistance to the FGFR inhibitors dovitinib and NVP-BGJ398 and explore the mechanism of action of the drug-resistant mutations. We previously reported the N550K and V565I mutations caused resistance to dovitinib. The sensitivity/resistance of these FGFR2 mutants to emerging FGFR inhibitors including AZD4547, NVP-BGJ398 and LY2874455 has now been tested.

To gain insights into potential mechanisms of acquired resistance to FGFR inhibitors in EC cells we generated subclones of FGFR2mutant AN3CA, MFE280 and JHUEM-2 EC cells resistant to FGFR inhibitors PD173074, Dovitinib and NVP-BGJ398, respectively. Phospho- protein arrays, gene expression profiling, exome sequencing and SNP analysis were performed to identify genes and signalling pathways that mediate resistance to FGFR inhibitors. Sequencing of AN3CAresistant and MFE280resistant subclones excluded secondary FGFR2 mutations as the resistance mechanisms. Upregulation of downstream survival pathways such as pERK and pAKT was observed in some of the JHUEM-2resistant and AN3CAresistant subclones. To further characterise these subclones we are currently analysing data from exome sequencing and copy number analysis, to determine the molecular mechanisms of resistance in these cell lines. In the MFE280resistant cells resistance to FGFR inhibition is associated with an EMT phenotype. Signaling through pERK and pAKT is downregulated in these cells, suggesting that resistance is not mediated by activation of kinase-driven survival pathways. Analysis of expression data is underway to understand how these cells have become resistant to FGFR inhibitors. This research will provide insight into possible combination therapies that may combat drug resistance in FGFR-mutant endometrial cancer.

Citation Format: Leisl M. Packer, Sara Byron, David Loch, Farhad Dehkhoda, Andreas Wortmann, Xinyan Geng, Katia Nones, Sean Grimmond, John Pearson, Nic Waddell, Pamela Pollock. Elucidating mechanisms of resistance to FGFR inhibitors in endometrial cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1715. doi:10.1158/1538-7445.AM2014-1715
Abstract 1717: Downregulation of miR-217 correlates with resistance of ph+ leukemia cells to ABL tyrosine kinase inhibitors
Authors: Ikezoe Takayuki , Nishioka Chie , Yang Jing , Yokoyama Akihito
Published: May 2015

This study found that long-term exposure of chronic myelogenous leukemia (CML) K562 cells to BCR/ABL thyrosine kinase inhibirors (TKIs) caused drug-resistance in association with an increase in levels of DNA methyltransferases (DNMTs) and a decrease in levels of microRNAs (miRNAs) miR-217. These observations are clinically relevant; an increase in levels of DNMT3A in association with downregulation of miR-217 were noted in leukemia cells isolated from individuals with BCR/ABL TKI-resistant philadelphia chromosome positive acute lymphoblastic leukemia (Ph+ ALL) and CML. Further studies with TKI-resistant K562 cells found that forced expression of miR-217 inhibited expression of DNMT3A through a miR-217-binding site within the 3′-untranslated region of DNMT3A and sensitized these cells to growth inhibition mediated by the TKI. Of note, long-term exposure of K562 cells to dasatinib (10 nM) together with 5-Aza-2′-deoxycytidine (5-AzadC) (0.1 μM) potently inhibited proliferation of these cells in association with upregulation of miR-217 and downregulation of DNMT3A in vitro. In addition, a decrease in levels of DNMT3A and an increase in levels of miR-217 were noted in K562 tumors growing in immune deficient mice that were treated by the combination of 5-AzadC and dasatinib. Taken together, Ph+ leukemia cells acquire TKI-resistance via downregulation of miR-217 and upregulation of DNMT3A. Inhibition of DNMT3A by forced expression of miR-217 or 5-AzadC may be useful to prevent drug resistance in individuals who receive TKIs.

Citation Format: Takayuki Ikezoe, Chie Nishioka, Jing Yang, Akihito Yokoyama. Downregulation of miR-217 correlates with resistance of ph+ leukemia cells to ABL tyrosine kinase inhibitors. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1717. doi:10.1158/1538-7445.AM2014-1717
Abstract 1718: Schlafen 11 (SLFN11) is a critical determinant of cellular sensitivity to PARP inhibitors
Authors: Murai Junko , Josse Rozenn , Doroshow James H. , Pommier Yves
Published: May 2015

Poly(ADP-ribose)polymerases (PARP) are DNA damage sensors and major repair factors for DNA single-strand breaks. Since the discovery of the synthetic lethality of PARP inhibitors in homologous recombination-deficient cells, the mechanism by which PARP inhibitors exert their cytotoxicity has been dominantly interpreted as an accumulation of unrepaired single-strand breaks resulting from catalytic PARP inhibition. We recently reported that several PARP inhibitors have an additional cytotoxic mechanism by trapping PARP-DNA complexes (1). BMN 673 is the most potent PARP inhibitor to date in terms of cytotoxicity and PARP trapping potency (2). Nevertheless, the NCI60 data show that half of the 60 cell lines are tolerant to BMN 673. To elucidate the mechanisms of tolerance, we searched for genes with expression levels correlated to BMN 673 sensitivity, and found that Schlafen 11 (SLFN11) is one of the most positively correlated genes. Most cells without SLFN11 expression were tolerant to BMN 673. To examine the involvement of SLFN11 in BMN 673 sensitivity, we disrupted the SLFN11 gene in DU145 prostate cancer cells and EW8 Ewing's sarcoma cells where SLFN11 expression levels and BMN 673 sensitivities are high. Knocking out SLFN11 in DU145 and EW8 did not affect their cell growth or cell cycle progression under normal conditions, but diminished their hypersensitivity to BMN 673 and another PARP inhibitor, olaparib. Cell cycle analyses revealed that SLFN11-proficient cells arrested at S phase while SLFN11 deficient cells were able to progress to G2 phase in the presence of BMN 673. Interestingly, arresting points at S phase in SLFN11 proficient cells were earlier when more PARP-DNA complexes were induced, suggesting that SLFN11 inhibits DNA replication under DNA damage. Differential kinetics of DNA repair and PARP-DNA complex formation were observed between SLFN11 proficient versus deficient cells. Our data suggest that the expression of SLFN11 may be a novel genomic biomarker for PARP inhibitor sensitivity.

1. Murai J, Huang S-yN, Das BB, Renaud A, Zhang Y, Doroshow JH, et al. Trapping of PARP1 and PARP2 by Clinical PARP Inhibitors. Cancer Research. 2012;72:5588-99.

2. Murai J, Huang SN, Renaud A, Zhang Y, Ji J, Takeda S, et al. Stereospecific PARP trapping by BMN 673 and comparison with olaparib and rucaparib. Mol Cancer Ther. 2014; Submitted.

Citation Format: Junko Murai, Rozenn Josse, James H. Doroshow, Yves Pommier. Schlafen 11 (SLFN11) is a critical determinant of cellular sensitivity to PARP inhibitors. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1718. doi:10.1158/1538-7445.AM2014-1718
Abstract 1719: Down-regulation of IGFBP2 is associated with resistance to IGF1R therapy in rhabdomyosarcoma
Authors: Kang Zhigang , Yu Yunkai , Zhu Yuelin J. , Helman Lee , Meltzer Paul , Cao Liang
Published: May 2015

Agents targeting the insulin-like growth factor-1 receptor (IGF1R) are in clinical development, but, despite some initial success of single agents in sarcoma, response rates are low with brief durations. Thus, it is important to identify markers predictive of response, to understand mechanisms of resistance, and to explore combination therapies. In this study, we found that, while associated with PAX3-FKHR translocation, increased IGF1R level is an independent prognostic marker for worse overall survival, particularly in patients with PAX3-FKHR-positive rhabdomyosarcoma (RMS). IGF1R antibody-resistant RMS cells were generated using an in vivo model. Expression analysis indicated that IGFBP2 is both the most affected gene in the IGF signaling pathway and the most significantly down-regulated gene in the resistant lines, indicating that there is a strong selection to repress IGFBP2 expression in tumor cells resistant to IGF1R antibody. IGFBP2 is inhibitory to IGF1R phosphorylation and its signaling. Similar to antibodies to IGF1/2 or IGF2, the addition of exogenous IGFBP2 potentiates the activity of IGF1R antibody against the RMS cells, and it reverses the resistance to IGF1R antibody. In contrast to IGF1R, lower expression of IGFBP2 is associated with poorer overall survival, consistent with its inhibitory activity found in this study. Finally, blocking downstream AKT activation with PI3K- or mTOR-specific inhibitors significantly sensitized the resistant cells to the IGF1R antibody. These findings show that constitutive IGFBP2 down-regulation may represent a novel mechanism for acquired resistance to IGF1R therapeutic antibody in vivo and suggest various drug combinations to enhance antibody activity and to overcome resistance.

Citation Format: Zhigang Kang, Yunkai Yu, Yuelin J. Zhu, Lee Helman, Paul Meltzer, Liang Cao. Down-regulation of IGFBP2 is associated with resistance to IGF1R therapy in rhabdomyosarcoma. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1719. doi:10.1158/1538-7445.AM2014-1719
Abstract 1722: Investigating resistance to AZD9291
Authors: Eberlein Cath , Ratcliffe Laura , O'Brien Lucy , Al-Khadimi Katie , Brown Henry , Fisher Paul , Stetson Daniel , Lai Zhongwu , Marshall Gayle , Barnes Claire , Thress Kenneth , Dougherty Brian , Pao William , Cross Darren
Published: May 2015

First- and second-generation EGFR TKIs are established first line therapy for patients with NSCLC with activating mutations in EGFR. Unfortunately, patients ultimately develop disease progression with acquisition of a second-site EGFR T790M mutation in more than half of cases. This has led to the development of third generation EGFR TKIs which inhibit both the EGFRm+ and T790M mutations in preclinical models and are showing activity in TKI-resistant patients in Phase I studies. Despite the potential improvements brought by third generation EGFR-TKIs, advanced EGFRm+ tumor cells will still remain highly adaptable and the inevitability of further resistance will limit the effectiveness of these drugs. As such, the identification of resistance mechanisms to these agents is essential to guide future therapeutic strategies and identify novel:novel combinations.

To interrogate resistance to AZD9291, we have generated panels of EGFRm+ cell lines resistant to gefitinib (first generation TKI) and EGFRm+ and EGFRm+/T790M cell lines resistant to afatinib and AZD9291 (second and third generation TKIs, respectively). Subsequently, we characterised the cell lines using a variety of molecular profiling techniques including Next Generation Sequencing (NGS), Affymetrix gene expression analysis, and phenotypic profiling following pharmacological modulation by small molecule inhibitors of canonical signaling pathways.

The effects on cell survival across the range of resistant models by a panel of pathway inhibitors indicated that resistance to the EGFR inhibitors, in particular AZD9291, is frequently associated with increased sensitivity to selumetinib (AZD6244; ARRY-142886) (MEK1/2 inhibitor), suggesting that ERK signaling is commonly reactivated to circumvent inhibition of the EGFR pathway. Molecular characterisation of the panel of cell lines suggests a range of different resistance mechanisms may be responsible for reactivation of ERK signaling, including a decrease in negative regulators of ERK such as DUSP6 or an epithelial to mesenchymal transition consistent with previous observations.

Collectively, these data suggest that combining an EGFR TKI with a MEK inhibitor could prevent or delay resistance and drive superior duration of benefit from these agents.

Citation Format: Cath Eberlein, Laura Ratcliffe, Lucy O'Brien, Katie Al-Khadimi, Henry Brown, Paul Fisher, Daniel Stetson, Zhongwu Lai, Gayle Marshall, Claire Barnes, Kenneth Thress, Brian Dougherty, William Pao, Darren Cross. Investigating resistance to AZD9291. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1722. doi:10.1158/1538-7445.AM2014-1722
Abstract 1734: In vitro characterization of EGF816, a third-generation mutant-selective EGFR inhibitor
Authors: Jia Yong , Juarez Jose , Manuia Mari , Lelais Gerald , Kasibhatla Shailaja , Long Oliver , McNeill Matthew , DiDonato Michael , Bursulaya Badry , Liao Debbie , Murphy Eric , Epple Robert , Marsilje Thomas , Pathan Nuzhat , Michellys Pierre-Yves , Bender Steven , Harris Jennifer
Published: May 2015

EGFR is a major oncogene in NSCLC. Patients with the oncogenic mutations L858R and Ex19Del are responsive to the first generation pan-EGFR tyrosine kinase inhibitors (TKIs) erlotinib and gefitinib. The associated dose-limiting toxicities (DLTs) are severe rash and GI tolerability due to WT EGFR inhibition. However, therapy is universally limited by the development of acquired drug resistance where EGFR gatekeeper mutation T790M accounts for 50% of incidence. Second generation irreversible pan-EGFR TKI afatinib was developed to overcome T790M resistance. Though effective in animal models, the efficacy of afatinib on T790M patients is largely limited by its DLTs due to potent inhibition of WT EGFR. A strong medical need still exists for better tolerated therapy to treat NSCLC patients harboring EGFR mutations. Here we report the discovery and development of a potent third generation, irreversible mutant-selective EGFR TKI that is expected to improve/maintain efficacy on oncogenic EGFR mutant patients while demonstrating reduced side effects. EGF816 potently inhibits both activating (L858R and Ex19Del) and T790M resistant mutations in various cellular assays; it is selective against a large panel of kinases in both Ambit and BaF3 profiling, and more importantly is selective against WT EGFR. EGF816 is efficacious in mutant EGFR-driven xenograft models, is well tolerated in IND-enabling toxicology studies, and is entering phase 1 trials.

Citation Format: Yong Jia, Jose Juarez, Mari Manuia, Gerald Lelais, Shailaja Kasibhatla, Oliver Long, Matthew McNeill, Michael DiDonato, Badry Bursulaya, Debbie Liao, Eric Murphy, Robert Epple, Thomas Marsilje, Nuzhat Pathan, Pierre-Yves Michellys, Steven Bender, Jennifer Harris. In vitro characterization of EGF816, a third-generation mutant-selective EGFR inhibitor. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1734. doi:10.1158/1538-7445.AM2014-1734
Abstract 1753: GLPG1790: The first Ephrin (EPH) receptor tyrosine kinase inhibitor for the treatment of triple negative breast cancer
Authors: Pujuguet Philippe , Beirinckx Filip , Delachaume Carole , Huck Jacques , Aar Ellen Van der , Brys Reginald , Rompaey Luc Van , Wigerinck Piet , Saniere Laurent
Published: May 2015

Receptor tyrosine kinases define a clinically relevant class of targets in the field of cancer. Here we report the discovery of a pre-clinical drug candidate directed against the EPH receptor family. Members of this family of receptor tyrosine kinases are over-expressed in diverse cancer types. GLPG1790 is a small molecule, nanomolar inhibitor of various EPH receptors kinases. The compound displayed a remarkable efficacy by once-daily oral administration in a mouse EPHA2 expressing xenograft model (MDA-MB-231). A rapid dose-dependent reduction of tumor growth was achieved, with full inhibition at the oral dose of 30 mg/kg/d. GLPG1790 efficacy at this dose was similar to that of Paclitaxel administered at its maximum tolerated dose. A series of experiments was initiated to confirm the mechanism of action of this compound. GLPG1790 inhibits human EPHA2 kinase activity with an IC50 of 11 nM in a biochemical assay. In the human MDA-MB-231 breast cancer cell line, that expresses a high level of EPHA2 protein, GLPG1790 inhibits receptor phosphorylation with an IC50 of 260 nM, and anchorage-independent growth with similar potency. In addition, in vivo target engagement was demonstrated in the mouse MDA-MB-231 xenograft model. GLPG1790 inhibited EPHA2 receptor phosphorylation after single oral administration of 30 and 100 mg/kg doses. The extent of the effects observed on EPHA2 phosphorylation correlated with intra-tumoral GLPG1790 concentration. Moreover, the MAPK pathway, known to be a major driver of proliferation of this cell line, was inhibited both in in vitro cellular assays and in xenograft target engagement studies. Flow cytometric analyses revealed a cell cycle arrest at the G0/G1 phase for MDA-MB-231 cells treated with GLPG1790. EPHA2 knock-down-based experiments further support the EPH-driven mode of action of GLPG1790. All together these data stimulate the development of GLPG1790 in triple negative breast cancer. This novel mechanism of action is under investigation in other cancer types overexpressing EPH's (melanoma, pancreatic, ovarian, prostatic and colorectal cancers).

Citation Format: Philippe Pujuguet, Filip Beirinckx, Carole Delachaume, Jacques Huck, Ellen Van der Aar, Reginald Brys, Luc Van Rompaey, Piet Wigerinck, Laurent Saniere. GLPG1790: The first Ephrin (EPH) receptor tyrosine kinase inhibitor for the treatment of triple negative breast cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1753. doi:10.1158/1538-7445.AM2014-1753
Abstract 1762: Phosphodiesterase 10, a novel target for colorectal cancer therapeutics
Authors: Lee Kevin J. , Li Nan , Chen Xi , Zhu Bing , Yet Larry , Piazza Gary
Published: May 2015

Phosphodiesterase 10 (PDE10) is a newly characterized PDE isozyme that is expressed in regions of the brain affecting cognition and psychomotor activity. Inhibitors are currently being developed for the treatment of schizophrenia and Huntington's disease, one of which, Pf-2545920 (MP-10), is in clinical trials. Although PDE10 is not expressed in most peripheral tissues, we recently found high levels in colon tumor cells compared with normal colonocytes and that genetic silencing by siRNA selectively suppressed colon tumor cell growth. These observations suggest that PDE10 may represent a novel anticancer target. Pf-2545920 was found to selectively inhibit colon tumor cell growth. Here we show that PDE10 knockdown reduced the sensitivity of colon tumor cells to Pf-2545920. Consistent with the ability of PDE10 to degrade cGMP and cAMP, Pf-2545920 activated both PKG and PKA as determined using site-specific phospho-VASP antibodies. Treatment of colon tumor cells with Pf-2545920 induced caspase activation as well as cytotoxicity. A novel PDE10 inhibitor, MCI-030, was found to potently inhibit colon tumor cell lines with IC50 values in the 0.3μM range without significantly affecting the growth of normal colonocytes. MCI-030 appears to exhibit selectivity for cGMP PDE10 signaling over cAMP shown by the activation of PKG but not PKA at doses that match those which inhibit growth. PDE10 knockdown cells were appreciably less sensitive to MCI-030 as well. These findings support a novel role of PDE10 as a therapeutic target for the treatment or prevention of colorectal cancer.

Citation Format: Kevin J. Lee, Nan Li, Xi Chen, Bing Zhu, Larry Yet, Gary Piazza. Phosphodiesterase 10, a novel target for colorectal cancer therapeutics. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1762. doi:10.1158/1538-7445.AM2014-1762
Abstract 1768: A novel PDE10 inhibitor suppresses tumor growth in an orthotopic mouse model of lung cancer
Authors: Ramirez-Alcantara Veronica , Schuler Michele A. , Zhu Bing , Li Nan , Gurpinar Evrim , Canzoneri Joshua , Keeton Adam , Gary Bernard , Russo Suzanne , Coward Lori , Gorman Gregory S. , Grizzle William , Chen Xi , Piazza Gary A.
Published: May 2015

Background: Conventional chemotherapy and radiation cannot distinguish between cancer and normal cells resulting in dose-limiting toxicity. Molecular targeted drugs hold greater promise, but few targets are unique to cancer cells and drugable. Our laboratory discovered that the cyclic nucleotide phosphodiesterase, PDE10, is elevated in human lung tumor cells and essential for their growth. A novel PDE10 inhibitor, MCI-020 was designed to achieve high lung concentrations and found to selectively inhibit the growth of human lung tumor cells in vitro. Objective: Evaluate pharmacokinetics, tissue distribution and antitumor efficacy of MCI-020 in mice. Material and Methods: MCI-020 (100 mg/kg) was formulated as a suspension and administrated orally to C57BL/6 female mice. Free levels of MCI-020 were quantified in plasma and tissues by reverse-phase chromatography with tandem mass spectrometry detection. For efficacy evaluation, athymic nude-Foxn1nu female mice were treated with MCI-020 (150 mg/kg bid) for 5 days before inoculation with 1x106 A549 cells/mouse into the left lung. After inoculation, MCI-020 treatment continued for 4 weeks. Anti-tumor efficacy of MCI-020 was evaluated by gross and histological grading of the lungs. Results: MCI-020 displayed attractive oral bioavailability and reached appreciably higher concentrations in lungs compared with plasma. MCI-020 treatment showed strong anti-tumor efficacy in the orthotopic mouse model of lung cancer and was well tolerated. Compared with the vehicle group in which 85% of the mice formed lung tumors, only 25% of the mice in the treatment group developed tumors. Histological grading of the extent of tumor formation revealed a score of 0.83 ± 0.3 (low involvement) for the treatment group, compared with 2.6 ± 0.4 (high involvement) for the vehicle group. Conclusions: These observations support a critical role of PDE10 in lung tumor growth and suggest that PDE10 inhibitors will be useful for the prevention or treatment of lung cancer. This project is supported by NIH grant 1R01CA148817.

Citation Format: Veronica Ramirez-Alcantara, Michele A. Schuler, Bing Zhu, Nan Li, Evrim Gurpinar, Joshua Canzoneri, Adam Keeton, Bernard Gary, Suzanne Russo, Lori Coward, Gregory S. Gorman, William Grizzle, Xi Chen, Gary A. Piazza. A novel PDE10 inhibitor suppresses tumor growth in an orthotopic mouse model of lung cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1768. doi:10.1158/1538-7445.AM2014-1768