Modeling the Causal Role of DNA Methylation in the Association Between Cigarette Smoking and Inflammation in African Americans: A 2-Step Epigenetic Mendelian Randomization Study
AMERICAN JOURNAL OF EPIDEMIOLOGY
Authors: Jhun, Min A.; Smith, Jennifer A.; Ware, Erin B.; Kardia, Sharon L. R.; Mosley, Thomas H., Jr.; Turner, Stephen T.; Peyser, Patricia A.; Park, Sung Kyun
Abstract
The association between cigarette smoking and inflammation is well known. However, the biological mechanisms behind the association are not fully understood, particularly the role of DNA methylation, which is known to be affected by smoking. Using 2-step epigenetic Mendelian randomization, we investigated the role of DNA methylation in the association between cigarette smoking and inflammation. In 822 African Americans from the Genetic Epidemiology Network of Arteriopathy, phase 2 (Jackson, Mississippi; 2000-2005), study population, we examined the association of cigarette smoking with DNA methylation using single nucleotide polymorphisms identified in previous genome-wide association studies of cigarette smoking. We then investigated the association of DNA methylation with levels of inflammatory markers using cis-methylation quantitative trait loci single nucleotide polymorphisms. We found that current smoking status was associated with the DNA methylation levels (M values) of cg03636183 in the coagulation factor II (thrombin) receptor-like 3 gene (F2RL3) (M = -0.64, 95% confidence interval (CI): -0.84, -0.45) and of cg19859270 in the G protein-coupled receptor 15 gene (GPR15) (M = -0.21, 95% CI: -0.27, -0.15). The DNA methylation levels of cg03636183 in F2RL3 were associated with interleukin-18 concentration (-0.11 pg/mL, 95% CI: -0.19, -0.04). These combined negative effects suggest that cigarette smoking increases interleukin-18 levels through the decrease in DNA methylation levels of cg03636183 in F2RL3.
High expression of F2RL3 correlates with aggressive features and poor survival in clear cell renal cell carcinoma
JOURNAL OF CANCER
Authors: Cao, Dalong; Qu, Yuanyuan; Zhang, Xuan; Xu, Fujiang; Zhou, Shuxian; Zhang, Guiming; Dai, Bo; Zhu, Yao; Shi, Guohai; Shen, Yijun; Zhu, Yiping; Zhang, Hailiang; Ye, Dingwei; Zhao, Jianyuan
Abstract
Background: Specific lifestyle factors including tobacco-exposure are vital etiologic factors for renal cell carcinoma (RCC), F2R Like Thrombin/Trypsin Receptor 3 (F2RL3) is associated with smoking but it is unknown whether its expression translate into poor survival of clear cell RCC (ccRCC). In the current study, the expression profiling and prognostic value of F2RL3 in Chinese patients with ccRCC were investigated. Methods: Using Quantitative PCR analysis and immunohistochemistry, the relative expression levels of F2RL3 in 367 paired ccRCC and adjacent normal tissues were calculated. Cox regression analysis was used to identify independent prognostic factors and Kaplan-Meier analysis and a log-rank test were employed to evaluate the prognostic value of F2RL3. Results: We observed that high expression of F2RL3 mRNA and protein were strongly correlated with shorten progression-free survival (PFS) of ccRCC with hazard ratios (HR; 95% confidence interval (CI)) of 2.060 (1.410-3.009) and 1.657 (1.193-2.300), respectively, as well as with poor overall survival (OS) with HRs (95%CI) of 2.826 (1.713-4.662) and 1.712 (1.140-2.569), respectively. After adjustment for confounding factors including smoking status, elevated HRs (95%CI) of 2.113 (1.445-3.089) and 1.692 (1.218-2.352) were presented for PFS, respectively, and 2.936 (1.777-4.851) and 1.811 (1.203-2.725) were present for OS, respectively. Meanwhile, increased F2RL3 mRNA and protein level were reported to significantly associate with smoking-exposure and well-known prognostic factors (higher TNM stage and ISUP grade). Conclusion: These findings suggested that F2RL3 mRNA and protein level in ccRCC is a robust predictor of poorly prognostic phenotype. Exploring the causal relevance of F2RL3 in ccRCC development further warrants in the future study.