Tan, Xiang‐Lin

Abstract Purpose: Growing mechanistic and epidemiologic evidence suggests that both metformin and statins have anti-cancer effects and are associated with reduced pancreatic cancer mortality. However, the joint effect of combination statin/metformin on pancreatic cancer mortality is unknown. By applying a robust analytic approach, we aim to examine the association between metformin and/or statin use and overall survival in a large cohort of patients with primary pancreatic adenocarcinoma (PDAC). Patients and Methods: 12,572 elderly patients with primary PDAC diagnosed between 2008 and 2012 were identified by using the Surveillance, Epidemiology, and End Results (SEER), and the detailed information on metformin and statin use was extracted from Medicare Part D. A Cox proportional hazard model with time-varying covariate adjusted for the propensity score was applied to assess the association of metformin and /or statin use with overall survival while controlling for potential confounders. Results: Of total 12,572 PDAC patients (median age = 76 years), 11,526 (91.77%) patients died before the study ended with a median follow-up of 3.8 months (interquartile range: 1.4-10.1). By the time-varying covariate analysis, statin use was significantly associated with an improved overall survival [Hazard ratio (HR), 0.938; 95% confidence interval (CI), 0.898 to 0.979], and more pronounced in post-diagnosis statin users (HR, 0.693; 95% CI, 0.555 to 0.864). However, metformin use was not significantly associated with overall survival (HR, 1.011; 95% CI, 0.939 to 1.091), neither in pre-diagnosis users (HR, 1.015; 95% CI, 0.970 to 1.061) nor in post-diagnosis users (HR, 0.990; 95% CI, 0.866 to 1.131). Additionally, no superior beneficial effect was observed for dual users (HR, 0.998; 95% CI, 0.947 to 1.053). Conclusions: Exposures to statin, not metformin, was significantly associated with reduced overall mortality of PDAC, indicating potential benefits of statin use on improving survival among PDAC patients. Further prospective validation is required to confirm these findings. Citation Format: Jian-Yu E, Shou-En Lu, Yong Lin, Judith M. Graber, David Rotter, Lanjing Zhang, Gloria M. Petersen, Kitaw Demissie, Grace Lu-Yao, Xiang-Lin Tan. Effects of concomitant metformin and statins on overall survival of pancreatic cancer patients: results from SEER-Medicare data analyses [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 3288. doi:10.1158/1538-7445.AM2017-3288

Abstract Background: Published evidence indicates that individual use of metformin and statin is associated with reduced cancer mortality. However, their differential and joint effects on pancreatic cancer survival are inconclusive. Methods: We identified a large population-based cohort of 12,572 patients ages 65 years or older with primary pancreatic ductal adenocarcinoma (PDAC) diagnosed between 2008 and 2011 from the Surveillance, Epidemiology, and End Results (SEER)-Medicare-linked database. Exposure to metformin and statins was ascertained from Medicare Prescription Drug Event files. Cox proportional hazards models with time-varying covariates adjusted for propensity scores were used to assess the association while controlling for potential confounders. Results: Of 12,572 PDAC patients, 950 (7.56%) had used metformin alone, 4,506 (35.84%) had used statin alone, and 2,445 (19.45%) were dual users. Statin use was significantly associated with improved overall survival [HR, 0.94; 95% confidence interval (CI), 0.90–0.98], and survival was more pronounced in postdiagnosis statin users (HR, 0.69; 95% CI, 0.56–0.86). Metformin use was not significantly associated with overall survival (HR, 1.01; 95% CI, 0.94–1.09). No beneficial effect was observed for dual users (HR, 1.00; 95% CI, 0.95–1.05). Conclusions: Our findings suggest potential benefits of statins on improving survival among elderly PDAC patients; further prospective studies are warranted to corroborate the putative benefit of statin therapy in pancreatic cancer. Impact: Although more studies are needed to confirm our findings, our data add to the body of evidence on potential anticancer effects of statins. Cancer Epidemiol Biomarkers Prev; 26(8); 1225–32. ©2017 AACR.

Abstract BACKGROUND Metformin, a widely used anti-diabetic drug, is being considered as a highly promising agent for treatment and prevention of many types of cancer, including breast cancer. Although the exact mechanism of action of metformin is unknown, it is thought that metformin is an AMPK activator. To better individualize metformin therapy and explore additional underlying molecular mechanism associated with metformin action, we conducted a metformin pharmacogenomic study using 266 genomic data-enriched lymphoblastoid cell lines (LCLs). METHODS Genome-wide microarray data were generated for all LCLs, including 1.3 million SNPs, 485K DNA methylation probes and 54K mRNA expression probe sets. Metformin cytotoxicity assay was performed using MTS assay. Genome-wide association (GWA) analyses and integrated analyses using all the genomic data and metformin cytotoxicity (IC50 value) were performed to identify top candidate genes for functional validation in breast cancer cell lines, MDA-MB 231 and Hs578T, using siRNA screening approach. Further mechanistic study was performed to investigate the role of candidates in regulation of AMPK activity. RESULTS GWA analyses in LCLs identified 198 mRNA expression probe sets and 210 DNA methylation probes associated with metformin IC50 with p-value <10-4, respectively. Analysis of 1.3 million SNPs found 12 loci (a region containing at least 1 SNP of p-value <10-5 and 1 SNP of p-value <10-3 within 50kb) that were associated with metformin IC50. Integrated SNP loci-mRNA expression-IC50 analysis indicated that the SNP loci on chromosome 16 was associated with metformin IC50 through a trans-regulation of expression of 7 genes with p-value <10-4. Integrated methylation-mRNA expression-IC50 analysis showed that 15 DNA methylation probes in 6 genes were associated with metformin IC50 through both cis- and trans-regulation of expression of 48 genes with p-value <10-4, including 4 methylation probes in 3 of those 6 genes that were cis-correlated with its own gene expression. Ingenuity pathway analysis of top 62 candidate genes identified four major pathways and 55 genes within those pathways were selected for functional validation in breast cancer cell lines. The knockdown experiment showed that down regulation of 25 genes significantly altered metformin sensitivity in MDA-MB231, and 14 of them also showed the same effect in Hs578T. Preliminary mechanistic experiment indicated that knockdown of 7 genes significantly reduced AMPK activity in MDA-MB231 and 3 of them had same effect in Hs578T. CONCLUSIONS GWAS using a genomic data-enriched LCL model system, together with functional validation in breast cancer cell lines, could help us to identify novel genetic and epigenetic biomarkers involved in metformin response and help us to better understand the mechanisms of metformin in cancer treatment. Citation Format: Nifang Niu, Xianglin Tan, Brooke L. Fridley, Daniel J. Schaid, Ryan P. Abo, Anthony Batzler, Erin E. Carlson, Gregory Jenkins, Sebastian Moran, Holger Andrea Heyn, Manel Esteller Badosa, Liewei Wang. Metformin pharmacogenomics: A genome-wide associate study to identify genetic and epigenetic biomarkers involved in metformin response. [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 2271. doi:10.1158/1538-7445.AM2013-2271

Abstract Integrative genomics has the potential to uncover relevant loci, as clinical outcome and response to chemotherapies are most likely not due to a single gene (or data type) but rather a complex relationship involving genetic variation, mRNA, DNA methylation, and copy number variation. In addition to this complexity, many complex phenotypes are thought to be controlled by the interplay of multiple genes within the same molecular pathway or gene set (GS). To address these two challenges, we propose an integrative gene set analysis approach and apply this strategy to a cisplatin (CDDP) pharmacogenomics study involving lymphoblastoid cell lines for which genome-wide SNP and mRNA expression data was collected. Application of the integrative GS analysis implicated the role of the RNA binding and cytoskeletal part GSs. The genes LMNB1 and CENPF, within the cytoskeletal part GS, were functionally validated with siRNA knockdown experiments, where the knockdown of LMNB1 and CENPF resulted in CDDP resistance in multiple cancer cell lines. This study demonstrates the utility of an integrative GS analysis strategy for detecting novel genes associated with response to cancer therapies, moving closer to tailored therapy decisions for cancer patients.

Abstract Background: Aspirin and nonsteroidal antiinflammatory drugs (NSAIDs) show indisputable promise as cancer chemoprevention agents. While aspirin and NSAID use have been suggested to lower risk of developing pancreatic cancer, the results of several epidemiological studies are not in consensus. Methods: Using a case-control design, we examined the association between aspirin, NSAID and acetaminophen use and the risk of pancreatic cancer. We enrolled 904 histological or clinically documented pancreatic ductal adenocarcinoma cases, and 1,223 age and gender matched healthy clinic-based controls evaluated at Mayo Clinic from April 2004 and September 2010. All subjects were ≥ 55 years old and self-reported by questionnaire their use of aspirin, NSAIDs, and acetaminophen at ages 41-60, along with extensive epidemiologic and demographic information. Multivariate logistic regression analysis was used to estimate risk of pancreatic cancer after adjusting for potential confounders. Results: The use of aspirin was associated with a decreased risk of pancreatic cancer. The unadjusted odds ratio (OR) associated with aspirin use ≥ 1 day/month, compared with never or < 1 day/month, was 0.79 [95% confidence interval (CI) 0.65. 0.96, p = 0.015]. This effect remained significant [OR 0.71, 95% CI 0.58,0.87, p = 0.0008], after adjusting for the potential confounders of body mass index and smoking status (never, former, current). The inverse relationship was stronger among former smokers (OR 0.61, 95% CI 0.46, 0.82, p =0.0008) than never and current smokers, although there was not a statistically significant interaction (Pintereaction = 0.333). NSAID and acetaminophen use was not associated with the risk of pancreatic cancer. Conclusions: Results from this large case-control study suggest that aspirin use, but not non-aspirin NSAID use, was associated with lower risk of developing pancreatic cancer and was more pronounced among former smokers than never and current smokers. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 1902. doi:10.1158/1538-7445.AM2011-1902

Abstract Background: Candidate gene and candidate pathway-based pharmacogenomic studies have been used to investigate the inherited variability of prognosis of lung cancer treated with platinum-based chemoptherapy. In order to make it possible to conduct an ‘unbiased’ query across the entire genome, a genome-wide association study (GWAS) in 283 lymphoblastoid cell lines (LCLs) was carried out to help identify candidate SNPs associated with variation in cisplatin cytotoxicity. Furthermore, we set out to test the hypothesis that genetic variation resulting in differences in cisplatin cytotoxicity might influence the overall survival of patients with lung cancer treated with platinum-based antineoplastic agents. Material and Methods: We applied ethnically diverse Coriell “Human Variation Panel” LCLs for GWAS. Then, we picked 168 top significant SNPs selected from GWAS in 283 LCLs and genotyped these SNPs in 1183 lung cancer patients (222 SCLC and 961 NSCLC) who received platinum-based chemotherapy. Genotyping was performed using the Illumina Golden Gate platform. The association of SNPs with lung cancer overall survival was analyzed by Cox regression model after adjusting for disease stage. Functional validation of candidate genes was performed by siRNA screening in NSCLC cell lines CRL5872, H1299 and SCLC cell line CRL5823. Results: A total of 157 SNPs were successfully genotyped for 1183 lung cancer patient samples. The Cox regression analysis indicated that 9 and 10 different SNPs were associated with overall survival for NSCLC and SCLC patients, respectively (p value <0.05). Fifteen genes including 7 genes located in the region of 200kb up or downstream of 4 SNPs (rs11169748, rs2440915, rs5952066 and rs7620841) and 8 genes for which the expression was correlated with three SNPs (rs11169748, rs2440915 and rs5952066) were selected for siRNA screening. Knockdown of DAPK3 and METTL6, for which the expression levels were correlated with the SNPs rs11169748 and rs2440915, significantly decreased cisplatin sensitivity in lung cancer cell lines CRL5872, H1299 and CRL5823. Conclusions: This series of clinical and complementary laboratory-based functional studies identified several candidate genes and SNPs that might help predict treatment outcomes of platinum-based therapy in lung cancer. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 1285. doi:10.1158/1538-7445.AM2011-1285

Abstract Many phytochemicals possess antioxidant and cancer-preventive properties, some putatively through antioxidant response element–mediated phase II metabolism, entailing mutagen/oxidant quenching. In our recent studies, however, most candidate phytochemical agents were not potent in inducing phase II genes in normal human lung cells. In this study, we applied a messenger RNA (mRNA)–specific gene expression–based high throughput in vitro screening approach to discover new, potent plant-derived phase II inducing chemopreventive agents. Primary normal human bronchial epithelial (NHBE) cells and immortalized human bronchial epithelial cells (HBECs) were exposed to 800 individual compounds in the MicroSource Natural Products Library. At a level achievable in humans by diet (1.0 μM), 2,3-dihydroxy-4-methoxy-4′-ethoxybenzophenone (DMEBP), triacetylresveratrol (TRES), ivermectin, sanguinarine sulfate, and daunorubicin induced reduced nicotinamide adenine dinucleotide phosphate:quinone oxidoreductase 1 (NQO1) mRNA and protein expression in NHBE cells. DMEBP and TRES were the most attractive agents as coupling potency and low toxicity for induction of NQO1 (mRNA level, ≥3- to 10.8-fold that of control; protein level, ≥ two- to fourfold that of control). Induction of glutathione S-transferase pi mRNA expression was modest, and none was apparent for glutathione S-transferase pi protein expression. Measurements of reactive oxygen species and glutathione/oxidized glutathione ratio showed an antioxidant effect for DMEBP, but no definite effect was found for TRES in NHBE cells. Exposure of NHBE cells to H2O2 induced nuclear translocation of nuclear factor erythroid 2–related factor 2, but this translocation was not significantly inhibited by TRES and DMEBP. These studies show that potency and low toxicity may align for two potential NQO1-inducing agents, DMEBP and TRES.

AbstractAspirin and other nonsteroidal anti-inflammatory drugs (NSAID) show indisputable promise as cancer chemoprevention agents. However, studies have been inconsistent as to whether aspirin has a protective effect in development of pancreatic cancer. To further evaluate the association between aspirin, NSAID, and acetaminophen use with pancreatic cancer risk, we used a clinic-based case–control study of 904 rapidly ascertained histologically or clinically documented pancreatic ductal adenocarcinoma cases, and 1,224 age- and sex-matched healthy controls evaluated at Mayo Clinic from April 2004 to September 2010. Overall, there is no relationship between non-aspirin NSAID or acetaminophen use and risk of pancreatic cancer. Aspirin use for 1 d/mo or greater was associated with a significantly decreased risk of pancreatic cancer (OR = 0.74, 95% CI: 0.60–0.91, P = 0.005) compared with never or less than 1 d/mo. Analysis by frequency and frequency-dosage of use categories showed reduced risk (P = 0.007 and 0.022, respectively). This inverse association was also found for those who took low-dose aspirin for heart disease prevention (OR = 0.67, 95% CI: 0.49–0.92, P = 0.013). In subgroup analyses, the association between aspirin use and pancreatic cancer was not significantly affected by pancreatic cancer stage, smoking status, or body mass index. Our data suggest that aspirin use, but not non-aspirin NSAID use, is associated with lowered risk of developing pancreatic cancer. Cancer Prev Res; 4(11); 1835–41. ©2011 AACR.

Abstract Purpose: Inherited variability in the prognosis of lung cancer patients treated with platinum-based chemotherapy has been widely investigated. However, the overall contribution of genetic variation to platinum response is not well established. To identify novel candidate single nucleotide polymorphisms (SNP)/genes, we carried out a genome-wide association study (GWAS) for cisplatin cytotoxicity by using lymphoblastoid cell lines (LCL), followed by an association study of selected SNPs from the GWAS with overall survival (OS) in lung cancer patients. Experimental Design: A GWAS for cisplatin was conducted with 283 ethnically diverse LCLs. A total of 168 top SNPs were genotyped in 222 small cell lung cancer (SCLC) and 961 non-SCLC (NSCLC) patients treated with platinum-based therapy. Association of the SNPs with OS was determined by using the Cox regression model. Selected candidate genes were functionally validated by siRNA knockdown in human lung cancer cells. Results: Among 157 successfully genotyped SNPs, 9 and 10 SNPs were top SNPs associated with OS for patients with NSCLC and SCLC, respectively, although they were not significant after adjusting for multiple testing. Fifteen genes, including 7 located within 200 kb up or downstream of the 4 top SNPs and 8 genes for which expression was correlated with 3 SNPs in LCLs were selected for siRNA screening. Knockdown of DAPK3 and METTL6, for which expression levels were correlated with the rs11169748 and rs2440915 SNPs, significantly decreased cisplatin sensitivity in lung cancer cells. Conclusions: This series of clinical and complementary laboratory-based functional studies identified several candidate genes/SNPs that might help predict treatment outcomes for platinum-based therapy of lung cancer. Clin Cancer Res; 17(17); 5801–11. ©2011 AACR.