bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract 89: Parathyroid Hormone-related Protein (PTHrP) is critical for breast tumour metastasis and may constitute a novel target for therapeutic intervention.
Authors: Li Jiarong , Karaplis Andrew C. , Huang Dao C. , Siegel Peter M. , Camirand Anne , Yang1 Xian Fang , Muller William J. , Kremer Richard
Published: August 2014

An increase in PTHrP circulating levels is associated with breast cancer recurrence and reduced survival. Despite the frequent association of PTHrP dysregulation with many tumor types, a precise and direct role for PTHrP in cancer development and progression has been difficult to prove, and its involvement in tumor initiation in vivo and in critical steps of malignant conversion is not clear. In this study, mice carrying a conditional PTHrP allele were crossed with the PyVMT transgenic mouse mammary tumor model and then with a separate transgenic strain expressing Cre in the mammary epithelium (MMTV/Cre). Circulating tumor cells (CTCs) were detectable in animals with PyVMT-PTHrPflox/flox-Cre−phenotype but not in animals with PyVMT-PTHrPflox/flox-Cre+ phenotype. The invasive ability in vitro of PyVMT-PTHrPflox/flox-Cre+cells was reduced by over 80% (P<0.001) as compared to control cells (PyVMT-PTHrP flox/flox-Cre−). Metastatic spread to lungs was seen in 100% of animals with PyVMT-PTHrP flox/flox-Cre− phenotype but none of the animals with PyVMT-PTHrP flox/flox-Cre+ phenotype. AKT1 and CXCR4 expression by Western blot and confocal microscope in both isolated cells and tumors from both genotypes. Akt 1 and CXCR4 expression by Western blot and immunofluorescence were markedly reduced (over 80% P<0.001) in PyVMT-PTHrPflox/flox-Cre+cells and tumors as compared to PyVMT-PTHrPflox/flox-Cre− cells and tumors. Anti-PTHrP neutralizing mAbs significantly inhibited matrigel invasion by human MDA-MB-435 breast cancer and their growth in vivo when injected into the MFPs of BALB/c nu/nu mice. After 6 weeks, approximately 100% of control animals presented lung metastases in contrast with 33% for mAb-treated mice the mAbs antibody reduced the expression of CXCR4 and AKT1 in mammary tumours by over 80% these results suggest that anti-PTHrP antibodies can be considered for therapeutic use against human breast cancer progression. Overall,our study demonstrates that PTHrP plays a crucial role in metastatic spread possibly by altering critical checkpoint of cancer progression and suggest its potential usefulness to prevent progression and recurrence of breast cancer. These results also suggest that anti-PTHrP antibodies can be considered for therapeutic use against human breast cancer progression.

Citation Format: Jiarong Li, Andrew C. Karaplis, Dao C. Huang, Peter M. Siegel, Anne Camirand, Xian Fang Yang1, William J. Muller, Richard Kremer. Parathyroid Hormone-related Protein (PTHrP) is critical for breast tumour metastasis and may constitute a novel target for therapeutic intervention. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 89. doi:10.1158/1538-7445.AM2013-89
Abstract 902: Role of ABCC10 in taxane mediated resistance in non-small cell lung carcinoma.
Authors: Wangari-Talbot Janet , Zhang Bruce , Hopper-Borge Elizabeth
Published: August 2014

Lung cancer is the leading cause of cancer deaths worldwide with non-small cell lung cancer (NSCLC) accounting for ∼85% of diagnosed cases. The 5 year survival rate for NSCLC is ∼15% with less than 7% of the patients alive 10 years after initial diagnosis. The taxanes, docetaxel and paclitaxel are potent chemotherapeutic drugs which result in cell cycle arrest and apoptosis through inhibition of microtubule depolymerization and are fundamental in cancer treatment regimens and are used as first line agents in NSCLC. Chemoresistance is a major obstacle in the treatment of NSCLC, an observation attributed in part to the drug efflux activity of the ATP Binding Cassette (ABC) transporter family proteins. ABCC10, a member of the ABC transporter family has been shown to confer resistance to various anti-neoplastic agents including docetaxel and paclitaxel in vitro. More importantly, Abcc10 null mice have been shown to exhibit increased tissue sensitivity to paclitaxel in vivo. Thus, ABCC10 may be an ideal target for investigation as a factor involved in reducing taxane efficacy. Here, we investigate whether ABCC10 has a role in taxane resistance in non-small cell lung carcinoma.

Human NSCLC cell lines were examined for ABCC10 expression by western immunoblots ABCC10 expression was then targeted for suppression using short-hairpin RNAs in the NSCLC cell lines A549 and H1299. Our results show that ABCC10 is expressed at varying levels in human NSCLC cell lines. Furthermore, suppression of ABCC10 in NSCLC cell lines resulted in increased cellular accumulation of docetaxel as well as a reduction in the efflux of the drug out of the cells. Further studies are needed to assess effects of ABCC10 in vivo on docetaxel sensitivity as well as the mechanisms involved in regulating ABCC10 activity.

Citation Format: Janet Wangari-Talbot, Bruce Zhang, Elizabeth Hopper-Borge. Role of ABCC10 in taxane mediated resistance in non-small cell lung carcinoma. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 902. doi:10.1158/1538-7445.AM2013-902
Abstract 905: Design and synthesis of regorafenib analogues against signal transducers and activators of transcription 3 in hepatocellular carcinoma cells.
Authors: Su Jung-Chen , Chen Kuen-Feng , Tai Wen-Tien , Huang Jui-Wen , Shiau Chung-Wai
Published: August 2014

Background: Regorafenib has been approved for the treatment of metastatic colorectal cancer (m-RCC) by FDA. The major targets of regorafenib are membrane-bound and intracellular kinases including RET, VEGFR1, VEGFR2, VEGFR3, KIT, PDGFR-alpha, PDGFR-beta, FGFR1, FGFR2, TIE2, DDR2, Trk2A, Eph2A, RAF-1, BRAF, BRAFV600E, SAPK2, PTK5, and Abl pathways. In HCC, signal transducers and activators of transcription 3 (STAT3) is a key transcription factor involving in cell proliferation and survival in hepatocellular carcinoma cells, Targeting STAT3 by small molecule is a promising strategy in HCC therapy. Methods: We have designed and synthesized a series of regorafenib analogues without kinase inhibitory activity. These compounds are treated with and analyzed in terms of STAT3 activity in HCC cell lines. Also, Effects of regorafenib analogues induced cell death are evaluated. Results: We demonstrate that regorafenib and its analogues repress STAT3 phosphorylation, subsequently abrogate STAT3-regulated protein, Mcl-1 and cyclin D1 and further induce apoptosis in HCC cells. Overexpression of STAT3 in PLC-5 cells attenuates apoptotic effect with regorafenib and its analogues treatment, suggesting STAT3, at least, is a major target. Interestingly, the new analugues of regorafenib are devoid of kinase inhibitory activity which implies the involvement of other regulation factors. The activity of negative regulator of STAT3, such as protein tyrosine phosphatases, is under investigation. In summary, the new analogues provide a lead for the design of a new class of agents that inhibit STAT3 along and synergize with clinical drugs in HCC.(Supported by NSC 100-2325-B-010-007)

Citation Format: Jung-Chen Su, Kuen-Feng Chen, Wen-Tien Tai, Jui-Wen Huang, Chung-Wai Shiau. Design and synthesis of regorafenib analogues against signal transducers and activators of transcription 3 in hepatocellular carcinoma cells. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 905. doi:10.1158/1538-7445.AM2013-905
Abstract 914: CIP2A mediates the effect of tamoxifen-induced apoptosis in estrogen receptor negative breast cancer cells.
Authors: Tseng Ling-Min , Liu Chun-Yu , Chang Kung-Chi , Wang Duen-Shian , Shiau Chung-Wai , Chen Kuen-Feng
Published: August 2014

Background: Tamoxifen is an antagonist of the estrogen receptor (ER) in breast tissue and has been a standard anti-estrogen agent in hormone receptor-positive breast cancers. Previous studies have indicated that tamoxifen also induces estrogen receptor-independent cell death in ER-negative breast cancer cells. Our previous study has shown that CIP2A, cancerous inhibitor of PP2A, may be a novel target in breast cancer cells (Breast Cancer Research 2012). Here, we tested efficacy of tamoxifen in a panel of ER-negative breast cancer cells and examined the drug mechanism. Methods: ER-negative breast cancer cell lines (HCC-1937, SK-BR3, MDA-MB-468, MDA-MB-453, MDA-MB-231) were used for in vitro studies. Apoptosis was examined by both flow cytometry and Western blot. Signal transduction pathways in cells were assessed by Western Blot. Gene silencing was done by small interference RNA (siRNA). In vivo efficacy of tamoxifen was tested in nude mice with breast cancer xenografts. Results: Tamoxifen showed differential effects on apoptosis in human ER-negative breast cancer cell lines. Tamoxifen induced significant apoptosis in SK-BR3, MDA-MB-468, MDA-MB-453, MDA-MB-231 cell lines; however, HCC-1937 cells were resistance to tamoxifen-induced apoptosis. Tamoxifen inhibited CIP2A in a dose-dependent manner in all sensitive ER-negative breast cancer cells, but not in resistant cells (HCC-1937). Overexpression of CIP2A protected MDA-MB-231 cells from tamoxifen-induced apoptosis. In addition, silencing CIP2A by siRNA sensitized HCC-1937 cells to tamoxifen-induced apoptosis. Moreover, in vivo xenograft data showed that tamoxifen inhibited the growth of MDA-MB-468 tumors but had no effect on HCC-1937 tumors. Furthermore, tamoxifen downregulated CIP2A in sensitive MDA-MB-468 xenograft tumors, but not in HCC-1937 tumors. Conclusions: Inhibition of CIP2A determines the effects of tamoxifen-induced apoptosis in ER-negative breast cancer cells. (Supported by Yen Tjing Ling Medical Foundation; NSC 101-2325-B-075-006 and NSC 100-2325-B-010-007; and V100-D-005-4)

Citation Format: Ling-Min Tseng, Chun-Yu Liu, Kung-Chi Chang, Duen-Shian Wang, Chung-Wai Shiau, Kuen-Feng Chen. CIP2A mediates the effect of tamoxifen-induced apoptosis in estrogen receptor negative breast cancer cells. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 914. doi:10.1158/1538-7445.AM2013-914
Abstract 915: Melanomas with rare BRAF mutations and their responses to MAPK pathway blocking drugs.
Authors: Atefi Mohammad S. , Ng Charles P. , Wong Deborah J. , Robert Lidia , Escuin-Ordinas Helena , Lassen Amanda , Foulad David , Comin-Anduix Begonya , Samatar Ahmad A. , Ribas Antoni
Published: August 2014

The BRAF V600E driver mutation is found in more than 50% of melanomas. Less common BRAF mutations of V600K, V600R, L597S, and G466K have also been identified. In these rare BRAF mutants, the effects of vemurafenib (Vem) and other MAPK pathway inhibitors on signaling, growth rate and clinical course are not well understood. In cell lines with rare BRAF mutations, we investigated the effect of Vem, inhibitors of Pan-RAF (Amgen 2112819), MEK (trametinib), ERK (MERK SCH772984), Pan-RAFi+ MEKi and ERKi+Vem on growth and signaling. These results were compared to the clinical responses to BRAF and MEK inhibitors in patients with the original tumors. Regardless of the mutation, no paradoxical activation of MAPK pathway by Vem was observed and the Pan-Rafi decreased levels of pMEK in all the cell lines. A heterozygous V600K mutated cell line was sensitive to Vem and more sensitive to the other drugs. Clinically, the duration of response to Vem in the patient the cell line was derived from was 7 months, and an additional 3 months to the combination of Vem and MEKi upon progression on Vem. In contrast, a homozygous V600K mutated cell line was resistant to Vem but sensitive to other MAPK inhibitors. The patient the cell line was derived from had a 5 month response to Vem followed by a 2 month response to the addition of a MEKi. BRAF L597S cell line was only sensitive to ERKi and G466K and V600R mutated cell lines were resistant to all the drugs. In general, Vem was the least effective followed by Pan-RAFi with ERKi stronger than both in most cell lines. The combination of Vem and ERKi showed similar or slightly higher growth inhibition than ERKi alone. In conclusion, MAPK inhibitors are not as effective in melanoma cell lines with rare BRAF mutations. However, more growth inhibition can be achieved by MEKi-Pan-RAFi combination. These in vitro data seem to be correlated with the clinical outcomes.

*Charles Ng, equal contribution

Citation Format: Mohammad S. Atefi, Charles P. Ng, Deborah J. Wong, Lidia Robert, Helena Escuin-Ordinas, Amanda Lassen, David Foulad, Begonya Comin-Anduix, Ahmad A. Samatar, Antoni Ribas. Melanomas with rare BRAF mutations and their responses to MAPK pathway blocking drugs. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 915. doi:10.1158/1538-7445.AM2013-915
Abstract 917: High antitumor activity of the ERK inhibitor SCH722984 against BRAF-mutant, NRAS-mutant and wild-type melanoma cell lines.
Authors: Wong Deborah J. , Robert Lidia , Atefi Mohammad S. , Foulad David , Avramis Earl V. , Comin-Anduix Begonya , Samatar Ahmed A. , Ribas Antoni
Published: August 2014

MAPK pathway dysregulation via mutations in proteins such as BRAFV600E and NRASQ61 is a key feature in melanomas, leading to constitutive ERK signaling. Currently, there are no FDA-approved targeted therapies effective in vemurafenib-resistant BRAFV600E mutant, NRAS mutant, or wild-type melanoma. The effect of SCH722984, an allosteric inhibitor of ERK 1/2, was determined in a panel of 53 melanoma cell lines, including wild-type, NRAS-mutant and vemurafenib-sensitive and resistant BRAF-mutant melanoma. 54% (13 of 24) of BRAF mutants, including 4 with innate vemurafenib resistance, were sensitive to SCH722984 with an IC50 <1μM. 100% (3 of 3) of BRAF/NRAS double mutants, 71% (10 of 14) of NRAS mutants and 71% (5 of 7) of wild-type melanomas were sensitive. 13% (5 of 24) of BRAF mutants, 14% (2 of 14) of NRAS mutants and 29% (2 of 7) of wild-type melanomas were intermediately sensitive (IC50 1-1.5μM). Among BRAFV600E mutants with in vitro acquired resistance to vemurafenib, those with MAPK pathway reactivation as the mechanism of resistance were sensitive to SCH722984. Combining vemurafenib and SCH722984 in BRAF mutant melanoma was synergistic in a majority of cell lines, resulting in up to 10-fold decrease in the 50% inhibitory concentration (IC50) and with combination indices (CI) below 1. SCH722984 inhibited phosphorylation of RSK, an ERK downstream target. Finally, long term cultures of two BRAFV600E-mutant cell lines sensitive to SCH722984 showed that treatment with SCH722984 alone or in combination with vemurafenib was more potent than vemurafenib alone and resulted in a significant delay in developing acquired resistance. SCH722984 may therefore be clinically applicable as a treatment for non-BRAF mutant melanoma or in BRAF-mutant melanoma with innate or acquired resistance, alone or in combination with BRAF inhibitors.

Citation Format: Deborah J. Wong, Lidia Robert, Mohammad S. Atefi, David Foulad, Earl V. Avramis, Begonya Comin-Anduix, Ahmed A. Samatar, Antoni Ribas. High antitumor activity of the ERK inhibitor SCH722984 against BRAF-mutant, NRAS-mutant and wild-type melanoma cell lines. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 917. doi:10.1158/1538-7445.AM2013-917
Abstract 927: Combined targeting c-Src and c-Met pathways to impair prostate cancer cell growth and invasion.
Authors: Dai Yao , Bae Kyung-Mi , Siemann Dietmar W.
Published: August 2014

Overexpression of tyrosine kinases c-Src and c-Met has been shown to be highly associated with prostate cancer progression and poor clinical outcomes, therefore small molecule Src or Met inhibitors are being extensively evaluated in clinical trials for advanced prostate cancer. However clinical data suggest that single treatment with any of these inhibitors only yield limited effects in patients. One possibility is that redundant signaling pathways in tumor cells exist that allows tumor cell uninterrupted upon blockade of purely one pathway. We hypothesize that c-Src and c-Met are two compensatory pathways that may cooperate to promote prostate cancer progression, hence here we studied treatment effects of combining inhibitors targeting c-Src (dasatinib, saracatinib) and c-Met (ASLAN002, also named BMS-777607) on multiple functional behaviors associated with tumor growth and metastasis in c-Src and c-Met expressing prostate cancer cells (PC-3, DU145). Combination of Src inhibitors and ASLAN002 was found to inhibit cell proliferation and colony formation more strongly than either single agent, as assessed by MTT and clonogenicity, respectively. In a wound-healing assay, compared to either treatment alone, the combinatorial treatment exhibited greater suppression on cell motility induced by hepatocyte growth factor, the only known ligand of c-Met. Similarly, using a Matrigel-based Transwell assay, Src inhibitors plus ASLAN002 resulted in significant reduction of cell invasion in the presence or absence of HGF. Western blot analysis demonstrated that co-targeting Met and Src kinases lead to not only inhibition on c-Met and c-Src autophosphorylation but also greater blockade of multiple downstream kinases such as focal adhesion kinase (FAK), Akt and extracellular signal-regulated kinase (ERK). These data indicate that combined application of small molecule Src and Met inhibitors cause significant impairment on various phenotypes associated with prostate cancer progression in vitro including proliferation, survival, migration and invasion, suggesting that this combination intervention modality may serve as a potential anti-metastatic strategy that could be further tested in metastatic prostate cancer models in vivo.

Citation Format: Yao Dai, Kyung-Mi Bae, Dietmar W. Siemann. Combined targeting c-Src and c-Met pathways to impair prostate cancer cell growth and invasion. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 927. doi:10.1158/1538-7445.AM2013-927
Abstract 93: CXCR4 expression in VHL-related and sporadic hemangioblastomas.
Authors: Kruizinga Roeliene C. , den Dunnen Wilfred F.A. , de Vries Elisabeth G.E. , Links Thera P. , Walenkamp Annemiek M.E.
Published: August 2014

Background & aim. Central nervous system hemangioblastomas are sporadically as well in patients with von Hippel-Lindau (VHL) disease. In VHL disease a germline mutation in the VHL- gene leads to a defect VHL protein. This results in enhanced transcription of vascular endothelial growth factor (VEGF)-A, chemokine receptor 4 (CXCR4) and its ligand (CXCL12). The aim of this study was to analyze whether VEGF-A, CXCR4, and CXCL12 protein expression differ between VHL-related and sporadic hemangioblastomas.

Methods. Freshly frozen tissue of patients operated in the University Medical Center Groningen the Netherlands, for hemangioblastomas between 1995-2010 was retrieved. Thirtythree samples of 27 patients were available, including 11 patients diagnosed with VHL-disease. Immunohistochemical analysis of 33 hemangioblastoma specimens (4 VHL patients and 1 sporadic patient were included more than once) was performed for hematoxylin & eosin, VEGF-A, CXCR4 and CXCL12 expression and compared with normal surrounding brain tissue. VEGF-A was evaluated describing morphology in relation to positive cells. A semi quantitative evaluation was performed for CXCL12; negative, positive (>1% positive cells) or strongly positive (>50 % positive cells or high intensity). CXCR4 was scored quantitatively by counting percentage of positive cells per specimen.

Results. VEGF-A was equally expressed in all sporadic and VHL-related hemangioblastomas, and present in hemangioblastoma cells and endothelial cells. CXCL12 was strongly expressed in 78% of hemangioblastoma tissues and did not differ between sporadic and VHL-related hemangioblastomas. In all hemangioblastomas CXCR4 was overexpressed as compared to the normal surrounding brain tissue (found in 15 specimens). Interestingly, in sporadic hemangioblastomas the mean percentage of CXCR4 positive cells per specimen (15%) was higher as compared to VHL-related hemangioblastomas (7%, p=0.001).

Conclusions. VEGF-A and CXCL12 protein expression was overexpressed in the majority of VHL-related and sporadic hemangioblastomas. This makes targeting VEGF-A a potential strategy for hemangioblastoma treatment. In addition, targeting CXCR4 could be of additional value as it was overexpressed in all hemangioblastomas, although differences in expression between sporadic and VHL related hemangioblastomas do exist.

Supported by a grant from the Jan Kornelis de Cock Stichting and a UEF-JSM Talent Grant to RC Kruizinga.

Citation Format: Roeliene C. Kruizinga, Wilfred F.A. den Dunnen, Elisabeth G.E. de Vries, Thera P. Links, Annemiek M.E. Walenkamp. CXCR4 expression in VHL-related and sporadic hemangioblastomas. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 93. doi:10.1158/1538-7445.AM2013-93
Abstract 943: RRM2: a key contributor in tamoxifen resistance in breast cancer.
Authors: Shah Khyati Niral , Peterson David , Evangelista Marie , Faridi Jesika
Published: August 2014

Tamoxifen is primarily used for early and advanced ER positive breast cancer patients. Unfortunately about 58% of the patients fail to respond to tamoxifen and eventually relapse with more aggressive tumors. Therefore, understanding the molecular mechanism of resistance is necessary to design new therapeutic strategies to overcome resistance. In this study, we show that Ribonucleotide Reductase M2 subunit is highly expressed in Akt over-expressing breast cancer cell lines and these breast cancer cell lines are highly resistant to tamoxifen treatment In-vitro. In these breast cancer cell lines, RNA interference mediated by small interfering RNA against RRM2 sensitizes these cells to tamoxifen-induced toxicity and reversed the tamoxifen resistance. Also, Using Oncomine database, we demonstrate that RRM2 is overexpressed in breast cancer. This is the first demonstration that investigate role of RRM2 in tamoxifen resistance and could serve as a potential target to restore tamoxifen sensititivity in breast cancer cells.

Citation Format: Khyati Niral Shah, David Peterson, Marie Evangelista, Jesika Faridi. RRM2: a key contributor in tamoxifen resistance in breast cancer. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 943. doi:10.1158/1538-7445.AM2013-943
Abstract 946: Mitochondrial division inhibitor 1 (mdivi-1) overcomes cisplatin resistance independent of dynamin-related protein 1 (Drp1).
Authors: Qian Wei , Roginskaya Vera , Strychor Sandra , Beumer Jan , McDermott Lee , Wang Jingnan , Van Houten Bennett
Published: August 2014

Platinum based anticancer agents including cisplatin are among the most effective and widely used anticancer drugs. However, the inherent and acquired resistance to these drugs in tumors present significant challenges in cancer treatment and directly lead to treatment failure. We have identified a number of thioquinazolinone derivatives, including the mitochondrial division inhibitor-1 (mdivi-1), that are able to effectively overcome both the inherent and acquired resistance to cisplatin and induce rapid apoptosis in several tumor cell lines. However, the enhanced cellular sensitivity to cisplatin by mdivi-1 was also observed in Drp1 (a mitochondrial fission protein and the supposed target of mdivi-1) knockout MEF cells, indicating Drp1-independent roles of these compounds in overcoming platinum drug resistance. The combination of cisplatin and mdivi-1 induces a robust replication stress response and enhances both intrinsic and extrinsic apoptotic signaling when compared with cisplatin or mdivi-1 treatment alone. Though the combined effect of cisplatin and mdivi-1 is not dependent on mitochondrial fission protein Drp1, mitochondria do play a significant role in the rapid execution of apoptosis triggered by this combination. Highly uncoupled mitochondria, increased generation of reactive oxygen species (ROS) and the release of apoptotic factors were observed only in cells treated with the combination of cisplatin and mdivi-1 and not in cells treated with the compounds individually. Taken together, we have identified novel functions for a set of thioquinazolinone derivatives that are able to overcome platinum drug resistance through enhancing replication stress-mediated apoptotic response.

Citation Format: Wei Qian, Vera Roginskaya, Sandra Strychor, Jan Beumer, Lee McDermott, Jingnan Wang, Bennett Van Houten. Mitochondrial division inhibitor 1 (mdivi-1) overcomes cisplatin resistance independent of dynamin-related protein 1 (Drp1). [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 946. doi:10.1158/1538-7445.AM2013-946
Abstract 959: Attenuation of hypoglycemia-associated resistance to PI103 and KU63794 through their synergistic combination in PIK3CA-mutant gastric cancer cells.
Authors: Bhattacharya Bhaskar , Low Sarah , Yee Meiqi , Koh King Xin , Soong Richie
Published: August 2014

Drug testing in vitro has traditionally been performed in hyperglycemic culture conditions, yet many tumours and their microenvironments are hypoglycemic. Hypoglycemia could contribute to drug resistance through many mechanisms such as activation of stress and survival pathways, and by altering tumour bioenergetics. The aim of this study was to evaluate if hypoglycemia reduces drug sensitivity, and test strategies to attenuate any resistance. Two gastric cancer (GC) cells with PIK3CA mutations (AGS, HGC27) and two without (MKN45, NUGC4) were cultured in routine high glucose (HG) (25mM) or low glucose (LG) (5mM) DMEM. The IC50s of PI103 (PI3K/mTOR inhibitor), and KU63794 (mTOR inhibitor) were measured at 72h using MTS assay. Protein and cell cycle analysis were performed by ELISA and PI/RNase staining respectively. Combination analysis was performed using combination index (CI) method of Chou and Talalay. Cells with mutant (mt) but not wildtype (wt) PIK3CA displayed significant resistance to both PI103 and KU63794 in LG compared to HG conditions (Table 1), despite having similar doubling times and cell cycle profiles. Basal protein analysis revealed increased p-mTOR, p-S6, p-4EBP1 and GLUT1 in PIK3CA mt cells grown in LG compared to HG conditions. The levels of these proteins did not differ in PIK3CA wt cells, in addition to p-Akt in all cells. The activation of the mTOR pathway prompted the testing of the combination of PI103 and KU63794. The combination was synergistic in AGS and HGC27 cells (CI=0.09, p=0.012 and CI=0.13, p=0.032 respectively) in LG conditions, and additive in HG conditions. Furthermore, synergy was associated with significant reduction in p-4EBP1 and extracellular lactate concentration. No synergy was seen in the wt cell lines. These results suggest that hypoglycemia can reduce drug sensitivity, and that resistance to PI103 and KU63794 in hypoglycemic conditions can be circumvented by combining the two agents.

Table 1. IC50 (μM) of PI103 and KU63794 in HG and LG conditions, * p < 0.01 Cell Line PIK3CA PI103 (HG) PI103 (LG) KU63794 (HG) KU63794 (LG) AGS Mutant 0.90 ± 0.02 7.2 ± 1.4* 0.5 ± 0.03 18.1 ± 1.3* HGC27 Mutant 0.45 ± 0.01 6.8 ± 0.4* 0.37 ± 0.01 20.1 ± 2.4* NUGC4 Wildtype 21.3 ± 4.7 22.4 ± 3.8 8.7 ± 6.5 6.9 ± 7.9 MKN45 Wildtype 1.8 ± 0.9 2.3 ± 1.8 3.4 ± 0.8 2.4 ± 0.6

Citation Format: Bhaskar Bhattacharya, Sarah Low, Meiqi Yee, King Xin Koh, Richie Soong. Attenuation of hypoglycemia-associated resistance to PI103 and KU63794 through their synergistic combination in PIK3CA-mutant gastric cancer cells. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 959. doi:10.1158/1538-7445.AM2013-959
Abstract 964: Gefitinib resistance due to STAT3-mediated Akt activation in lung cancer cells.
Authors: Wu Kai , Lu Yongju , Chen Bailing , Chang Qingshan , Qiu Ping , Yu Miaomiao
Published: August 2014

Epidermal Growth Factor Receptor (EGFR) tyrosine kinase inhibitors (TKIs), including gefitinib and erlotinib, are effective drugs for a subset of non-small cell lung cancer. Gefitinib binds to the tyrosine kinase domain of EGFR and hence inactivates its downstream prosurvival signaling pathways, including PI3k/Akt and MAPK pathways. However, most patients received gefitinib eventually developed resistance to this drug. In this study, we demonstrated that in gefitinib-treated A549 cells (human lung cancer cell line), Akt activation undergoes a time-dependent recovery following an initial inhibition by gefitinib. Since constant activation of Akt has been associated with treatment failure of gefitinib in lung cancer cells, exploring the mechanisms that lead to Akt restoration should provide new insights into the drug resistance and therapeutic efficacy. For that purpose, alterations in Akt activation and other signaling pathways, including MAPK and STAT3, involved in EGFR-mediated cellular responses were determined in A549 cells treated with gefitinib. Among them, we found that activation of STAT3 was inhibited in the cells without gefitinib treatment. Gefitinib treatment inhibited EGFR phosphorylation on tyrosine 1086 (Y1086), which leads to STAT3 activation. Further studies showed that interruption of the STAT3 signaling by either chemical inhibitor or siRNA against STAT3 prevented fast recovery of Akt activation and enhanced gefitinib-induced suppression of cell proliferation. Taken together, these data suggest that activation of STAT3 is an intrinsic mechanism of drug resistance in response to EGFR TKIs. Combinational targeting on both EGFR and STAT3 may enhance the efficacy of gefitinib or other EGFR TKIs on lung cancer.

Citation Format: Kai Wu, Yongju Lu, Bailing Chen, Qingshan Chang, Ping Qiu, Miaomiao Yu. Gefitinib resistance due to STAT3-mediated Akt activation in lung cancer cells. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 964. doi:10.1158/1538-7445.AM2013-964
Abstract 973: Salinomycin sensitized paclitaxel-resistant human ovarian cancer cells and induced apoptosis.
Authors: Cho Chi-Heum , Lee Hyun-Gyo , Parajuli Bidur , Shin So-Jin , Kwon Sang-Hoon , Cha Soon-Do
Published: August 2014

Ovarian cancer has the highest mortality rate among gynecologic malignancies in the world.

Drug resistance is the main cause of treatment failure and mortality in cancer patients. The objective of this study was to establish a paclitaxel (PTX)-resistant human ovarian carcinoma cell line (OVCAR3) and to sensitize chemoresistant cells. The drug-resistant tumor cell lines were established in vitro by stepwise sequential exposure to increased concentration of PTX. For sensitization, OVCAR3/PTX cells were treated with different concentration of salinomycin alone or combined with PTX. The cell viability and cell cycle distribution was measured by MTT and flow cytometric analysis. The transcriptional change of mRNA was examined by RT-PCR.

The induction of apoptosis was measured by caspase-3 activity test, DNA fragmentation assay and western blot analysis. The cell viability was significantly reduced by combination treatment in a dose dependent manner. The flow cytometry result showed an increase in sub-G1 phase. Combination treatment enhanced the sensitivity of OVCAR3/PTX cells to PTX with down-regulation of P-glycoprotein,

XIAP and survivin. Taken together, we demonstrated potential effect of salinomycin in sensitization of PTX resistant ovarian tumor growth. Our results suggest salinomycin in combination with PTX may be a beneficial chemotherapeutic strategy, especially in patients with tumors refractory to PTX alone.

Citation Format: Chi-Heum Cho, Hyun-Gyo Lee, Bidur Parajuli, So-Jin Shin, Sang-Hoon Kwon, Soon-Do Cha. Salinomycin sensitized paclitaxel-resistant human ovarian cancer cells and induced apoptosis. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 973. doi:10.1158/1538-7445.AM2013-973
Abstract 975: Sorafenib overcomes irinotecan resistance in colorectal cancer by inhibiting the ABCG2 drug-efflux pump..
Authors: Mazard Thibault , Causse Annick , Simony Joelle , Leconet Wilhem , Jarlier Marta , Ychou Marc , Del Rio Maguy , Martineau Pierre , Robert Bruno , Gongora Céline
Published: August 2014

Background: Despite recent advances in the treatment of colorectal cancer, tumor resistance is a frequent cause of chemotherapy failure. Thus, new treatment options are needed to improve survival of patients with irinotecan-refractory colorectal cancers, particularly those bearing KRAS mutations that preclude the use of anti-EGFR therapies. In this study, we investigated whether sorafenib could reverse irinotecan resistance, thereby enhancing the therapeutic efficacy of routinely used irinotecan-based chemotherapy.

Materials and methods: We used both in vitro (the HCT116, SW48, SW620 and HT29 colon adenocarcinoma cell lines and four SN-38 resistant HCT-116 and SW48 clones) and in vivo models (nude mice xenografted with SN-38 resistant HCT116 cells) to test the efficacy of sorafenib alone or in combination with irinotecan, or its active metabolite SN-38.

Results: Sorafenib improved the anti-tumoral activity of irinotecan in vitro, in both parental and SN-38 resistant colon adenocarcinoma cell lines independently of their KRAS status, as well as in vivo, in xenografted mice. By inhibiting the drug-efflux pump ABCG2, sorafenib favors irinotecan intracellular accumulation and enhances its toxicity.

Conclusion: Our results show that sorafenib can suppress resistance to irinotecan and suggest that sorafenib could be used to overcome resistance to irinotecan-based chemotherapies in colorectal cancer, particularly in KRAS mutated tumors.

Citation Format: Thibault Mazard, Annick Causse, Joelle Simony, Wilhem Leconet, Marta Jarlier, Marc Ychou, Maguy Del Rio, Pierre Martineau, Bruno Robert, Céline Gongora. Sorafenib overcomes irinotecan resistance in colorectal cancer by inhibiting the ABCG2 drug-efflux pump. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 975. doi:10.1158/1538-7445.AM2013-975
Abstract 983: A dual inhibitor of MDR-1 and ABCG2,elacridar, enhances cytotoxic effects of sunitinib on RCC cell lines.
Authors: Sato Hiromi , Siddig Sana , Suzuki Rina , Uzu Miaki , Suzuki Sayumi , Nomura Yuki , Sekine Yuko , Uehara Tomoya , Arano Yasushi , Ueno Koichi
Published: August 2014

Sunitinib is a multi-targeted receptor tyrosine kinase inhibitor (TKI) and currently approved for use in advanced renal cell carcinoma (RCC). It is really attractive drug for patients who cannot have surgical treatment. However, it is reported that TKI might be substrates of ATP-binding cassette (ABC) transporters, which are able to mediate the efflux of anti-tumor drugs from the tumor cells. In this study, we suggested that inhibition of MDR transporters by elacridar (dual inhibitor of MDR-1 and ABCG2) might overcome sunitinib resistance in experimental RCC.

We used 786-O and Caki-1 RCC cell lines. The cells were treated with sunitinib alone, elacridar alone or the combination, then cytotoxicity was measured by the MTT cytotoxicity method. The expression of MDR-1 and ABCG2 mRNA and their protein were detected by real time RT-PCR or Western blotting. Additionally, P-gp function was analyzed by using 99mTc-MIBI. MCF-7 cells were used as negative control for P-gp functional assay.

Our results showed that elacridar significantly enhanced sunitinib cytotoxicity in RCC cells. High P-gp expression was especially observed in 786-O, though that of ABCG2 was almost the same among cells. Additionally P-gp assay revealed that the protein would be active and elacridar blocked its function in 786-O, where the accumulation of the 99mTc-MIBI increased 7 folds compared to the control (non-treatment group).

These findings suggest that sunitinib resistance is partly mediated by gene and protein expression of MDR transporters. Therefore combination with elacridar could reverse its resistance in MDR sensitive cancer cells, as it did in 786-O.

Citation Format: Hiromi Sato, Sana Siddig, Rina Suzuki, Miaki Uzu, Sayumi Suzuki, Yuki Nomura, Yuko Sekine, Tomoya Uehara, Yasushi Arano, Koichi Ueno. A dual inhibitor of MDR-1 and ABCG2,elacridar, enhances cytotoxic effects of sunitinib on RCC cell lines. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 983. doi:10.1158/1538-7445.AM2013-983
Abstract 984: The role of TGF-alpha in the resistance to mesothelioma chemotherapy.
Authors: Neelature Sriramareddy Sathya , Vandermeers Fabian , Costa Chrisostome , Mascaux Céline , Scherpereel Arnaud , Delvenne Philippe , Hubert Pascale , Willems Luc L.
Published: August 2014

Background. Malignant mesothelioma (MM) is a cancer of the pleura caused mainly by the inhalation of asbestos fibers. The impact of chemotherapy on the outcome of patients with MM is still unclear. We hypothesized that unresponsiveness to chemotherapy is due to inadequate gene expression in tumor cells. We have previously shown that inhibitors of histones deacetylases (such as valproate, VPA) significantly increases the efficacy of compounds used in chemotherapy (Vandermeers et al, 2010, Clinical Cancer Research 15: 2818). A recent clinical trial on relapsing MM patients has shown that VPA in combination with doxorubicin improves response rates and quality of life (Scherpereel et al, 2011, European Respiratory Journal 37:129).

Results. To study the mechanisms associated with the response to chemotherapy, we compared two types of cell lines (M14K and H28) characterized by a difference in sensitivity to doxorubicin+VPA. Using Agilent microarrays and RT-qPCR, we observed that the basal expression level of TGFα was higher in "resistant" H28 compared to "sensitive" M14K cells. To evaluate the functional relevance of TGFα, we modulated its expression either by RNA interference or by transfection of a cDNA vector. A decrease of TGFα expression correlated with induction of apoptosis. Inversely, an inhibition of apoptosis occurred when TGFα was over-expressed. As TGFα is the ligand of EGFR, we tested the effect of gefitinib and erlotinib in combination with VPA+doxorubicin. Both EGFR inhibitors increased apoptosis induced by VPA+doxorubicin in H28 chemoresistant cells. Finally, the VPA+doxorubicin+erlotinib regimen prevented tumor growth in two mouse models (ZL34 in SCID and AB12 in Balb/c).

Conclusions. Our data demonstrates that TGFα is involved in the chemoresistance to VPA+doxorubicin, a second-line regimen for MM. Although inefficient alone, tyrosine kinase inhibitors synergize to induce apoptosis in chemoresistant cells and prevent tumor growth in mouse models.

Citation Format: Sathya Neelature Sriramareddy, Fabian Vandermeers, Chrisostome Costa, Céline Mascaux, Arnaud Scherpereel, Philippe Delvenne, Pascale Hubert, Luc L. Willems. The role of TGF-alpha in the resistance to mesothelioma chemotherapy. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 984. doi:10.1158/1538-7445.AM2013-984
Abstract 986: Sildenafil potentiates the anticancer activity of paclitaxel in ABCB1-mediated multidrug resistance xenograft model.
Authors: Sodani Kamlesh , Tiwari Amit K. , Dai Chun-ling , Abuznait Alaa H. , Xiao Zhi-jie , Kaddouni Amal , Chen Zhe-Sheng
Published: August 2014

The multidrug resistance (MDR) phenotype caused by the overexpression of ATP-binding cassette (ABC) transporters promotes the cellular efflux of a variety of anticancer drugs that may lead to cancer treatment failure. Previous in vitro studies from our group reported sildenafil, a PDE-5 inhibitor, could significantly block the function of ABCB1/P-glycoprotein and reverse ABCB1/P-glycoprotein-mediated MDR. In the current study we investigated the effect of sildenafil on the ABCB1-mediated MDR in vivo. To determine this effect we developed ABCB1-xenograft nude muse model using ABCB1 overexpressing KB-C2 cell line. We found that sildenafil significantly enhanced the chemotherapeutic response of paclitaxel in the ABCB1-xenograft nude mouse model. The combination treatment with sildenafil and paclitaxel attenuated the tumor growth synergistically. In addition, there was no visible toxicity, weight loss or other gross phenotypic changes with combination treatment. The positive effects of sildenafil can be attributed to inhibition of ABCB1-mediated drug efflux. This phenomenon was further supported by increased concentrations of paclitaxel in ABCB1-overexpressing tumors in the combination treatment group compared to paclitaxel alone. In addition, pharmacokinetic analysis showed increase in the plasma paclitaxel concentration in the combination group. These beneficial actions of sildenafil can be considered as viable option for combination therapy with the clinical anticancer drugs that succumb to ABCB1-mediated insensitivity.

Citation Format: Kamlesh Sodani, Amit K. Tiwari, Chun-ling Dai, Alaa H. Abuznait, Zhi-jie Xiao, Amal Kaddouni, Zhe-Sheng Chen. Sildenafil potentiates the anticancer activity of paclitaxel in ABCB1-mediated multidrug resistance xenograft model. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 986. doi:10.1158/1538-7445.AM2013-986
Abstract 988: F14512, a novel vectorized topoiserase II inhibitor, bypasses MDR1 mediated resistance.
Authors: Annereau Jean Philippe , Brel Viviane , Riquet William , Créancier Laurent , Vandenberghe Isabelle , Fournier Emmanuel , Robichon Céline , Stennevin Aline , Offrete Vanessa , Lacastaigneratte Laurence , Gomes Bruno , Kruczynski Anna , Bailly Christian , Guilbaud Nicolas
Published: August 2014

F14512 is a novel polyamine-vectorized topoisomerase II inhibitor currently in phase 1/2 clinical trial in acute myeloid leukemia (AML). Since ABCB1 (also called P-glycoprotein or MDR1) has been reported to be expressed at high levels in patients with resistant leukaemia cells, and constitutes a pejorative marker of therapy, we decided to investigate whether F14512 could be exported by ABCB1 or other ABC transporters susceptible to confer drug resistance to chemotherapy, such as MRP1. In addition, we established a F14512-resistant cell line to study the mechanism of resistance to the drug.

With membrane preparation enriched in functional MDR1, we found that F14512 was unable to stimulate the ATPase activity of this transporter. Using a cellular assay over expressing MDR1 transporter by recombinant transfection of MDCKII cells, F14512 was detectable, but the intracellular level was unchanged regardless of the MDR1 status or in presence of MDR1 competitors. Consistently, iterative selection of a F14512-resistant A-549 cell line with 36 cycles of F14512 at cytotoxic doses (0.5 EC50) over 9 months, led to only moderate shift of resistance (9 fold). In the resulting selected A-549 subclones, MDR1, MRP1 and ABCG2 were detectable at the basal level.

The ability of F14512 to bypass MDR1 was finally assessed in a vinorelbine-resistant P388 model overexpressing high level of functional ABCB1 as indicated with the positive rhodamine export assay and cross resistance to MDR1 substrate. Moreover, F14512 displays strong antileukemic activity in MDR1-positive P388 cells in vitro and additional in vivo measurements are in progress.

In conclusion, the data concur to show that the antitumor activity of the targeted cytotoxic agent F14512 is not impacted by the MDR1 status of cancer cells. MDR1 clearly does not affect the potency of F14512 and this characteristic augurs well for the ongoing development of the drug in AML patients.

Citation Format: Jean Philippe Annereau, Viviane Brel, William Riquet, Laurent Créancier, Isabelle Vandenberghe, Emmanuel Fournier, Céline Robichon, Aline Stennevin, Vanessa Offrete, Laurence Lacastaigneratte, Bruno Gomes, Anna Kruczynski, Christian Bailly, Nicolas Guilbaud. F14512, a novel vectorized topoiserase II inhibitor, bypasses MDR1 mediated resistance. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 988. doi:10.1158/1538-7445.AM2013-988