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  • American Association for Cancer Research (AACR)  (48)
  • Tong, Pan  (48)
  • 2015-2019  (48)
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  • American Association for Cancer Research (AACR)  (48)
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  • 2015-2019  (48)
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  • 1
    In: Cancer Research, American Association for Cancer Research (AACR), Vol. 76, No. 14_Supplement ( 2016-07-15), p. 4665-4665
    Abstract: Introduction: Activation of epidermal growth factor receptor (EGFR) leads to the development and progression of human epithelial cancers, including non-small cell lung cancer (NSCLC). EGFR tyrosine kinase inhibitors (EGFR-TKI) are effective therapy for NSCLC with activating EGFR mutations. However, acquired resistance to EGFR-TKIs is unavoidable and occurs through various molecular mechanisms including the development of T790M secondary EGFR mutations, MET amplification, epithelial-mesenchymal transition (EMT) and other mechanisms. One of potential strategy to overcome EGFR-TKIs is through inhibition of polo-like kinase 1 (PLK1). PLK1 is one of the key regulators of mitotic progression and a DNA damage recovery checkpoint. PLK1 inhibitors are at various stages of clinical development. Our previous studies showed that mesenchymal NSCLC cell lines are more sensitive to PLK1 inhibitor than epithelial ones. This study examines the efficacy of PLK1 inhibition in NSCLC cell lines with acquired resistance to the EGFR-TKI erlotinib. Methods: Erlotinib resistant cell lines were developed in EGFR mutant, erlotinib sensitive cell lines PC9, HCC4006 and HCC827 by chronic exposure to stepwise increased concentrations of erlotinib. The effects of the PLK1 inhibitor volasertib alone or combined with erlotinib on proliferation, apoptosis, cell cycle, EGFR-dependent signaling, DNA damage and DNA damage response signaling were evaluated using CellTiter-Glo assay, TUNEL assay, BrDU incorporation assay, comet assay, western blot and immunofluorescence. Sensitivity of volasertib alone or in combination with erlotinib was also detected in the human tumor xenograft model. The combination index (CI) was calculated by Calcusyn software. Results: Acquired erlotinib resistant NSCLC cell lines with endogenous EGFR mutations (PC9, HCC4006 and HCC827) showed diverse resistance mechanisms: T790M EGFR mutation, MET amplification and EMT. Four of the 6 ER clones that underwent EMT became more sensitive to volasertib. Volasertib and erlotinib demonstrated synergistic effects only in cells bearing T790M EGFR mutations where we observed more pronounced G2M arrest and increased apoptosis. Volasertib alone or in combination showed enhanced DNA damage, activation of CHK1/ATR and CHK2/ATM pathways and an increase in γH2AX foci but only a modest effect on canonical signaling downstream of EGFR. The combination treatment exhibited a pronounced reduction in the size of tumor compared to single agent treatment in subcutaneous xenograft model generated with T790M mutant EGFR TKI-resistant PC9 cell line. Conclusions: These data demonstrate that PLK1 inhibition alone induces apoptosis and DNA damage in EGFR-TKI resistant cell lines with EMT. The combination of volasertib and erlotinib overcomes T790M-mediated drug resistance in vitro and in vivo. Citation Format: Ratnakar Singh, Yuehong Wang, Liguang Wang, Monique Nilsson, Ruchitha Goonatilake, Pan Tong, Lerong Li, Uma Giri, Jing Wang, John V. Heymach, Faye M. Johnson. The combination of polo-like kinase 1 inhibition and erlotinib overcomes T790M-mediated drug resistance in vitro and in vivo in non-small cell lung cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4665.
    Type of Medium: Online Resource
    ISSN: 0008-5472 , 1538-7445
    RVK:
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    Language: English
    Publisher: American Association for Cancer Research (AACR)
    Publication Date: 2016
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  • 2
    In: Clinical Cancer Research, American Association for Cancer Research (AACR), Vol. 22, No. 7 ( 2016-04-01), p. 1674-1686
    Abstract: Purpose: To identify new therapeutic targets for non–small cell lung cancer (NSCLC), we systematically searched two cancer cell line databases for sensitivity data on a broad range of drugs. We identified polo-like kinase 1 (PLK1) as the most promising target for further investigation based on a subset of sensitive NSCLC cell lines and inhibitors that were in advanced clinical development. Experimental Design: To identify potential biomarkers of response of NSCLC to PLK1 inhibition and mechanisms of PLK1 inhibitor–induced apoptosis, integrated analysis of gene and protein expression, gene mutations, and drug sensitivity was performed using three PLK1 inhibitors (volasertib, BI2536, and GSK461364) with a large panel of NSCLC cell lines. Results: The NSCLC cell lines had different sensitivities to PLK1 inhibition, with a minority demonstrating sensitivity to all three inhibitors. PLK1 inhibition led to G2–M arrest, but only treatment-sensitive cell lines underwent substantial apoptosis following PLK1 inhibition. NSCLC lines with high epithelial–mesenchymal transition (EMT) gene signature scores (mesenchymal cell lines) were more sensitive to PLK1 inhibition than epithelial lines (P & lt; 0.02). Likewise, proteomic profiling demonstrated that E-cadherin expression was higher in the resistant cell lines than in the sensitive ones (P & lt; 0.01). Induction of an epithelial phenotype by expression of the miRNA miR-200 increased cellular resistance to PLK1 inhibition. Also, KRAS mutation and alterations in the tight-junction, ErbB, and Rho signaling pathways correlated with drug response of NSCLC. Conclusions: In this first reported large-scale integrated analysis of PLK1 inhibitor sensitivity, we demonstrated that EMT leads to PLK1 inhibition sensitivity of NSCLC cells. Our findings have important clinical implications for mesenchymal NSCLC, a significant subtype of the disease that is associated with resistance to currently approved targeted therapies. Clin Cancer Res; 22(7); 1674–86. ©2015 AACR.
    Type of Medium: Online Resource
    ISSN: 1078-0432 , 1557-3265
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    Language: English
    Publisher: American Association for Cancer Research (AACR)
    Publication Date: 2016
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  • 3
    In: Cancer Research, American Association for Cancer Research (AACR), Vol. 79, No. 1 ( 2019-01-01), p. 125-132
    Abstract: Glutathione (GSH)/GSH reductase (GSR) and thioredoxin/thioredoxin reductase (TXNRD) are two major compensating thiol-dependent antioxidant pathways that maintain protein dithiol/disulfide balance. We hypothesized that functional deficiency in one of these systems would render cells dependent on compensation by the other system for survival, providing a mechanism-based synthetic lethality approach for treatment of cancers. The human GSR gene is located on chromosome 8p12, a region frequently lost in human cancers. GSR deletion was detected in about 6% of lung adenocarcinomas in The Cancer Genome Atlas database. To test whether loss of GSR sensitizes cancer cells to TXNRD inhibition, we knocked out or knocked down the GSR gene in human lung cancer cells and evaluated their response to the TXNRD inhibitor auranofin. GSR deficiency sensitized lung cancer cells to this agent. Analysis of a panel of 129 non–small cell lung cancer (NSCLC) cell lines revealed that auranofin sensitivity correlated with the expression levels of the GSR, glutamate-cysteine ligase catalytic subunit (GCLC), and NAD(P)H quinone dehydrogenase 1 (NQO1) genes. In NSCLC patient-derived xenografts with reduced expression of GSR and/or GCLC, growth was significantly suppressed by treatment with auranofin. Together, these results provide a proof of concept that cancers with compromised expression of enzymes required for GSH homeostasis or with chromosome 8p deletions that include the GSR gene may be targeted by a synthetic lethality strategy with inhibitors of TXNRD. Significance: These findings demonstrate that lung cancers with compromised expression of enzymes required for glutathione homeostasis, including reduced GSR gene expression, may be targeted by thioredoxin/thioredoxin reductase inhibitors.
    Type of Medium: Online Resource
    ISSN: 0008-5472 , 1538-7445
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    Language: English
    Publisher: American Association for Cancer Research (AACR)
    Publication Date: 2019
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  • 4
    In: Cancer Research, American Association for Cancer Research (AACR), Vol. 77, No. 19 ( 2017-10-01), p. 5313-5326
    Abstract: Chromophobe renal cell carcinoma (ChRCC) is characterized by major changes in chromosomal copy number (CN). No model is available to precisely elucidate the molecular drivers of this tumor type. HNF1B is a master regulator of gene expression. Here, we report that the transcription factor HNF1B is downregulated in the majority of ChRCC and that the magnitude of HNF1B loss is unique to ChRCC. We also observed a strong correlation between reduced HNF1B expression and aneuploidy in ChRCC patients. In murine embryonic fibroblasts or ACHN cells, HNF1B deficiency reduced expression of the spindle checkpoint proteins MAD2L1 and BUB1B, and the cell-cycle checkpoint proteins RB1 and p27. Furthermore, it altered the chromatin accessibility of Mad2l1, Bub1b, and Rb1 genes and triggered aneuploidy development. Analysis of The Cancer Genome Atlas database revealed TP53 mutations in 33% of ChRCC where HNF1B expression was repressed. In clinical specimens, combining HNF1B loss with TP53 mutation produced an association with poor patient prognosis. In cells, combining HNF1B loss and TP53 mutation increased cell proliferation and aneuploidy. Our results show how HNF1B loss leads to abnormal mitotic protein regulation and induction of aneuploidy. We propose that coordinate loss of HNF1B and TP53 may enhance cellular survival and confer an aggressive phenotype in ChRCC. Cancer Res; 77(19); 5313–26. ©2017 AACR.
    Type of Medium: Online Resource
    ISSN: 0008-5472 , 1538-7445
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    Language: English
    Publisher: American Association for Cancer Research (AACR)
    Publication Date: 2017
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  • 5
    In: Clinical Cancer Research, American Association for Cancer Research (AACR), Vol. 21, No. 15 ( 2015-08-01), p. 3480-3491
    Abstract: Purpose: Thyroid transcription factor-1 (TTF1) immunohistochemistry (IHC) is used clinically to differentiate primary lung adenocarcinomas (LUAD) from squamous lung cancers and metastatic adenocarcinomas from other primary sites. However, a subset of LUAD (15%–20%) does not express TTF1, and TTF1-negative patients have worse clinical outcomes. As there are no established targeted agents with activity in TTF1-negative LUAD, we performed an integrated molecular analysis to identify potential therapeutic targets. Experimental Design: Using two clinical LUAD cohorts (274 tumors), one from our institution (PROSPECT) and The Cancer Genome Atlas, we interrogated proteomic profiles (by reverse phase protein array, RPPA), gene expression, and mutational data. Drug response data from 74 cell lines were used to validate potential therapeutic agents. Results: Strong correlations were observed between TTF1 IHC and TTF1 measurements by RPPA (Rho = 0.57, P & lt; 0.001) and gene expression (NKX2-1, Rho = 0.61, P & lt; 0.001). Established driver mutations (e.g., BRAF and EGFR) were associated with high TTF1 expression. In contrast, TTF1-negative LUAD had a higher frequency of inactivating KEAP1 mutations (P = 0.001). Proteomic profiling identified increased expression of DNA repair proteins (e.g., Chk1 and the DNA repair score) and suppressed PI3k/mTOR signaling among TTF1-negative tumors, with differences in total proteins confirmed at the mRNA level. Cell line analysis showed drugs targeting DNA repair to be more active in TTF1-low cell lines. Conclusions: Combined genomic and proteomic analyses demonstrated infrequent alteration of validated lung cancer targets (including the absence of BRAF mutations in TTF1-negative LUAD), but identified novel potential targets for TTF1-negative LUAD, including KEAP1/Nrf2 and DNA repair pathways. Clin Cancer Res; 21(15); 3480–91. ©2015 AACR.
    Type of Medium: Online Resource
    ISSN: 1078-0432 , 1557-3265
    RVK:
    Language: English
    Publisher: American Association for Cancer Research (AACR)
    Publication Date: 2015
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  • 6
    In: Cancer Research, American Association for Cancer Research (AACR), Vol. 77, No. 13_Supplement ( 2017-07-01), p. 298-298
    Abstract: Background: WEE1 inhibitors (WEEi) are a novel class of small molecule inhibitors that are now under early clinical trials for small cell lung cancer (SCLC). WEE1 is a protein kinase that plays a key role in regulating the G2 checkpoint in response to DNA damage. Moreover, because WEE1 inhibition induces a HR deficient state, dual targeting of WEE1 and PARP (another promising target previously identified in our group) may induce synthetic lethality. In the present study we evaluate the efficacy of AZD1775 alone and with the PARP inhibitor, olaparib; investigate the mechanisms of primary resistance to AZD1775 in SCLC models; and assess the combinatorial efficacy of AZD1775 treatment with the chemotherapy drug, temozolomide (TMZ), that has shown promise in patients with recurrent SCLC and has been included in the National Comprehensive Cancer Network guidelines for standard treatment for SCLC. Results: Combination of AZD1775 with olaparib revealed an additive effect in vitro in 90% of SCLC cell lines. AZD1775 combined with TMZ synergistically decreased viability, increased DNA damage and apoptosis in SCLC cell lines (n=10) irrespective of MGMT status or initial response to AZD1775 alone. However, unlike the sensitive cells, SCLC cell lines showing primary resistance to AZD1775 had an intact DNA repair mechanism (after DNA damage), which may contribute to the resistance mechanism. Proteomic analysis revealed AXL (receptor tyrosine kinase) and phospho-S6K (S240/244) as markers of AZD1775 resistance and treatment with AXL inhibitor, TP0903 (40nM), resensitized the cells to AZD1775. Pre and post-AZD1775 treated samples revealed sustained activation of mTOR pathway in AZD1775 primary resistant lines. We further demonstrated that pre-treatment of the cells with the mTOR inhibitor everolimus sensitized SCLC cells to AZD1775 by causing downregulation of AKT/mTOR pathway. Conclusion: WEE1 inhibitors are currently in clinical trials for SCLC patients. However, as with any targeted therapy, drug resistance is an important barrier to clinical benefit which could be addressed with therapeutic combinations. We show the efficacy of single agent AZD1775 and in combination with olaparib. WEE1 inhibitor, AZD1775 synergizes with TMZ irrespective of MGMT status in all tested in vitro models which warrants further clinical investigation. We also show that the activity of the WEE1 inhibitors might be limited in cancer cells overexpressing of AXL and activated mTOR pathway and that AXL and mTOR inhibition re-sensitized the cells to AZD1775. Our work supports further exploration of the combination of PARP and WEE1 in SCLC and also the possibility of AXL/mTOR inhibition as a mechanism to overcome WEE1 inhibition resistance in SCLC. SCLC is a disease with very limited therapeutic options and no targeted agents with proven benefit; thus the results from this study have clear translational benefit. Citation Format: Triparna Sen, Pan Tong, Lixia Diao, You Hong-Fan, C. Allison Stewart, John V. Heymach, Jing Wang, Lauren A. Byers. WEE1 inhibitor activity correlates to AXL/mTOR expression and exhibits synergy with temozolomide (TMZ) in small cell lung cancer (SCLC) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 298. doi:10.1158/1538-7445.AM2017-298
    Type of Medium: Online Resource
    ISSN: 0008-5472 , 1538-7445
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    Language: English
    Publisher: American Association for Cancer Research (AACR)
    Publication Date: 2017
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  • 7
    In: Cancer Research, American Association for Cancer Research (AACR), Vol. 77, No. 13_Supplement ( 2017-07-01), p. 1560-1560
    Abstract: Resistance to therapy, including conventional chemotherapy, targeted therapy and immunotherapy, continues to plague cancer treatment. Moreover, mechanisms governing resistance are poorly characterized leading to a dearth of rational combinatorial and sequential treatment strategies. While drug response data is abundant across myriad tumor types and drug classes, there exists no high-throughput method to probe such data with a query as simple as “If tumors are resistant to drug X, to what drug(s) are they sensitive?”- a seemingly trivial problem beset by immense data sets and imprecise definitions of sensitivity and resistance. Here, we present DISARM, a novel approach designed specifically to screen for drugs that are active in spite of resistance to a reference drug. DISARM selects candidates based on the proportion of samples that are resistant to a reference drug but sensitive to a candidate drug with simultaneous consideration to relatively lower IC50 values for candidate drugs and higher IC50 values for reference drugs. As candidates may work in only a subset of resistant models and precise delineation between sensitivity and resistance may vary between experimental settings, DISARM permits flexibility in dichotomizing drug data and uses grid search to optimize specifications. To illustrate, we analyzed publically available cell line data (IC50 data) from several cancer types for which platinum-based therapy is a standard of care, identifying multiple drugs that demonstrate activity in cisplatin-resistant models across tumor types such as the BCL-2 inhibitor obatoclax in small cell lung cancer, lung adenocarcinoma, gastric adenocarcinoma and bladder cancer, and the farnesyltransferase inhibitor tipifarnib in small cell lung cancer, bladder cancer, esophageal cancer, colon adenocarcinoma and head and neck squamous cell carcinoma. Frequently, multiple drugs from the same class were selected by DISARM for a single tumor type and, in these cases, we found statistically significant similarity between sensitive cell lines suggesting a subset of cisplatin-resistant cell lines that are repeatedly sensitive to a drug class. While translating preclinical observations into approved clinical use is often thwarted by an inability to identify predictive biomarkers, DISARM also allows us to select cell lines that are especially sensitive to candidate drugs or drug classes on which to perform biomarker analysis. To demonstrate this approach, we chose drugs with activity in multiple cancer types and compared mRNA and protein expression data to highlight potentially novel common and tumor-specific biomarkers for concomitant candidate drug sensitivity and cisplatin resistance. Thus, DISARM offers a simple yet effective approach for both drug and biomarker discovery within a specified clinical niche. Citation Format: Carl M. Gay, Pan Tong, Robert J. Cardnell, Xiao Su, Nene N. Kalu, Upasana Banerjee, Rasha O. Bara, Faye M. Johnson, John V. Heymach, Jing Wang, Lauren A. Byers. Differential sensitivity analysis for resistant malignancies (DISARM), a novel approach for drug screen analysis, identifies common candidate drugs across platinum-resistant cancer types [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1560. doi:10.1158/1538-7445.AM2017-1560
    Type of Medium: Online Resource
    ISSN: 0008-5472 , 1538-7445
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    Language: English
    Publisher: American Association for Cancer Research (AACR)
    Publication Date: 2017
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  • 8
    In: Cancer Research, American Association for Cancer Research (AACR), Vol. 77, No. 13_Supplement ( 2017-07-01), p. 3816-3816
    Abstract: The genomic alterations identified in head and neck squamous cell carcinoma (HNSCC) tumors have not resulted in any changes in clinical care, making the development of biomarker-driven targeted therapy for HNSCC a major translational gap in knowledge. To fill this gap, we used 59 molecularly characterized HNSCC cell lines and found that mutations of AJUBA,SMAD4 and RAS predicted sensitivity and resistance to treatment with inhibitors of polo-like kinase 1 (PLK1), checkpoint kinases 1 and 2, and WEE1. Inhibition or knockdown of PLK1 led to cell-cycle arrest at the G2/M transition and apoptosis in sensitive cell lines and decreased tumor growth in an orthotopic AJUBA-mutant HNSCC mouse model. AJUBA protein expression was undetectable in most AJUBA-mutant HNSCC cell lines, and total PLK1 protein expression was increased in cell lines wild-type for AJUBA. Exogenous expression of wild-type AJUBA in an AJUBA-mutant cell line partially rescued the phenotype of PLK1 inhibitor-induced apoptosis and decreased PLK1 substrate inhibition, suggesting a threshold effect in which higher drug doses are required to affect PLK1 substrate inhibition. PLK1 inhibition was an effective therapy for HNSCC in vitro and in vivo. However, biomarkers to guide such therapy are lacking. We identified AJUBA, SMAD4 and RAS mutations as potential candidate biomarkers of response of HNSCC to treatment with these mitotic inhibitors. Citation Format: Ming Zhang, Singh Ratnakar, Shaohua Peng, Mazumdar Tuhina, Shen Li, Pan Tong, Curtis Pickering, Jeffrey N. Myers, Jing Wang, Faye M. Johnson. Mutations of the lim protein ajuba mediate sensitivity of head and neck squamous cell carcinoma to treatment with cell cycle inhibitors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3816. doi:10.1158/1538-7445.AM2017-3816
    Type of Medium: Online Resource
    ISSN: 0008-5472 , 1538-7445
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    Language: English
    Publisher: American Association for Cancer Research (AACR)
    Publication Date: 2017
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  • 9
    Online Resource
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    American Association for Cancer Research (AACR) ; 2016
    In:  Cancer Research Vol. 76, No. 14_Supplement ( 2016-07-15), p. 3870-3870
    In: Cancer Research, American Association for Cancer Research (AACR), Vol. 76, No. 14_Supplement ( 2016-07-15), p. 3870-3870
    Abstract: Small cell lung cancer (SCLC) is an aggressive disease that accounts for 14% of lung cancers. Very little progress has been made towards the treatment of SCLC in the past four decades and there are no established biomarkers to predict effective therapies for patients. In other cancers, SLFN11 plays an important role in sensitizing cancer cells to topoisomerase inhibitors, DNA synthesis inhibitors and alkylating agents. Previously, our lab identified an increase in poly (ADP-Ribose) polymerase 1 (PARP1), an enzyme involved in DNA damage repair, in SCLC patients and cell lines. PARP inhibitors demonstrate significant anti-tumor activity in cell line and animal models of SCLC and are currently being tested in clinical trials for SCLC patients. In Ewing sarcoma (EWS), SLFN11 has been proposed as a biomarker of PARP inhibitor response. Because both EWS and SCLC have high PARP levels and respond favorably to PARP inhibition, we hypothesized that SLFN11 may also be a biomarker for drug sensitivity in SCLC. Using SCLC patient tumors and a large panel of molecularly profiled SCLC cell lines, we investigated the expression of SLFN11 in SCLC and its association with in vitro sensitivity to PARP inhibition (olaparib) and chemotherapy. SLFN11 mRNA levels are significantly higher in SCLC patient tumors relative to normal lung tissue (P = 0.005). In a panel of 51 SCLC cell lines, higher SLFN11 protein expression correlates with both cisplatin (P & lt;0.001) and olaparib (PARP inhibitor; P = 0.05) sensitivity. In fact, SLFN11 is the top protein biomarker of cisplatin sensitivity in SCLC cell lines (of 171 proteins measured). Consistent with what has been shown for other cancer types, SLFN11 mRNA expression is also correlated with sensitivity to irinotecan (P = 0.005) and topotecan (P = 0.05) in SCLC, two drugs frequently used to treat this disease. Expression of other SLFN family members does not correlate with drug sensitivity. SLFN11 protein and mRNA levels are concordant (P & lt;0.001) and both demonstrate a bimodal expression pattern in SCLC cell lines which corresponds to cisplatin (protein, P & lt;0.001; mRNA, P = 0.005) and olaparib (mRNA, P = 0.05) sensitive (SLFN11 high) versus resistant (SLFN11 low) groups. In EWS, leukemia, colon, breast and prostate cancers, SLFN11 functions as an ETS transcription factor response gene. However, a panel of 26 ETS transcription factors did not correlate well with SLFN11 or PARP1 mRNA expression or cisplatin sensitivity, suggesting that SLFN11 expression may be regulated in a different manner in SCLC. In summary, SLFN11 is a predictor of sensitivity to chemotherapies routinely used in the treatment of SCLC, including alkylating agents (cisplatin) and topoisomerase inhibitors (irinotecan, topotecan). Moreover, SLFN11 predicts in vitro response to PARP inhibition, which may have important clinical implications given the ongoing clinical trials investigating PARP as a novel therapeutic target for SCLC. Citation Format: C. Allison Stewart, Pan Tong, Robert Cardnell, Triparna Sen, Fatemah Mina Masrorpour, Youhong Fan, Jing Wang, Lauren Averett Byers. SLFN11 is a biomarker of sensitivity to PARP inhibition and chemotherapy in small cell lung cancer (SCLC). [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3870.
    Type of Medium: Online Resource
    ISSN: 0008-5472 , 1538-7445
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    Language: English
    Publisher: American Association for Cancer Research (AACR)
    Publication Date: 2016
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  • 10
    In: Cancer Research, American Association for Cancer Research (AACR), Vol. 76, No. 14_Supplement ( 2016-07-15), p. 393-393
    Abstract: Recently published whole exome sequencing studies in head and neck squamous cell carcinoma (HNSCC) tumors revealed that few had therapeutically targetable alterations using current strategies. This finding defines translational gap between genomics and HNSCC treatment. One potential targetable alteration is PIK3CA mutations. However, clinical trials testing PI3K/mTOR pathway inhibitors have had limited success and these inhibitors only lead to cell cycle arrest in PIK3CA mutant HNSCC cell lines. Thus, there is a critical need to identify therapeutic vulnerabilities for common mutation groups, including tumor suppressors, in HNSCC. One of these molecular subgroups is NOTCH1 which is the second most frequently mutated gene in HNSCC, with a 10-15% prevalence of inactivating mutations. Although there are several studies underscoring the importance of NOTCH1 as a tumor suppressor in HNSCC, none has identified a therapy that targets NOTCH1 mutant (mut) HNSCC. Our objective was to identify predictive biomarkers of sensitivity to PI3K/mTOR inhibitors by integrating drug and multiple-omics data. Cell viability with six PI3K/mTOR inhibitors in 68 HNSCC lines was measured by the CellTiter Glo assay. The peak plasma concentration of each drug was used as the cut-off to determine sensitivity. We observed a striking correlation between NOTCH1mut and sensitivity to PI3K/mTOR pathway inhibitors. When fisher's exact test was performed, NOTCH1mut lines were more sensitive to GSK2126458 (P & lt;0.027), BYL719 (P & lt;0.004) and PQR309 (P & lt;0.014) than NOTCH1 wild type cell lines. NOTCH1 was also identified as an upstream regulator in sensitive cell lines by Ingenuity® Pathway Analysis. Basal NOTCH1 protein expression was higher in HNSCC lines resistant to PI3K/mTOR inhibition using unsupervised hierarchical clustering of Reverse Phase Protein Array data. NOTCH1mut lines underwent more apoptosis after GSK2126458 treatment compared to NOTCH1wt lines (PCI15B- 48.1 fold; P & lt;0.05, HN31- 46.9 fold; P & lt;0.05). There was also increased accumulation of cells in G1 after GSK2126458 treatment in NOTCH1mut lines (PCI15B-1.3 fold, P & lt;0.05; HN31- 1.4 fold, P & lt;0.05). To check if inhibition of NOTCH1 pathway inhibition sensitizes NOTCH1wt lines to PI3K/mTOR inhibition, resistant NOTCH1wt lines were treated with Gamma secretase inhibitors and GSK2126458. The combination led to significantly decreased cell viability (DAPT- 1.5 fold and YO010227- 1.7 fold). The combination studies will be further expanded to 38 NOTCH1wt lines. On-going studies include assessment of drug sensitivity in vivo, mechanistic studies and the effect of genetic manipulation of NOTCH1 signaling on sensitivity to PI3K/mTOR inhibitors. Our data suggests that loss of active NOTCH1 signaling confers sensitivity to PI3K/mTOR inhibition. If the combination of NOTCH1 and PI3K/mTOR inhibition leads to apoptosis, this combination could be translated into the clinic. Citation Format: Faye M. Johnson, Vaishnavi Sambandam, Li Shen, Ming Zhang, Rishi Saigal, Pan Tong, Tuhina Mazumdar, Lauren A. Byers, Curtis Pickering, Jeffrey N. Myers, Jing Wang, Mitchell Frederick. NOTCH1 inactivating mutation mediates sensitivity to PI3K/mTOR inhibitors in head and neck squamous cell carcinoma. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 393.
    Type of Medium: Online Resource
    ISSN: 0008-5472 , 1538-7445
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    Language: English
    Publisher: American Association for Cancer Research (AACR)
    Publication Date: 2016
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