Abstract: Objective The Objective of this study was to investigate the relationship between the methylation of phosphodiesterase 4C(PDE4C)gene in peripheral blood leukocytes,and its interaction with environmental factors and the pathogenesis of breast cancer.Methods A case-control study was conducted to select 402 cases of breast cancer and 470 cancer-free controls from October 2010 to December 2014.The specific DNA methylation-modified quantitative PCR method was used to detect the methylation of PDE4C gene.The use of crossover analysis and multivariate logistic regression was used to analyze the relationship between the level of gene methylation and its interaction with environmental factors and the pathogenesis of breast cancer.Results PDE4C methylation was not found to be significantly associated with the onset of breast cancer.High-frequency/high-intake of whole grains,vegetables,onion-based plants,poultry,milk,and regular exercise could reduce the risk of breast cancer;high-frequency/high-intake of pork,irregular menstrual cycle,and a high psychological stress index could increase the risk of breast cancer.PDE4C hypermethylation had a significant combining effect with edible onion-producing plants greater than 3 times/week,with an OR of 0.373(95% CI:0.208~0.668,P=0.001).Conclusion Hypermethylation of PDE4C is not an independent risk factor for breast cancer,and its combination with environmental factors affects the risk of breast cancer.

Key words: Breast cancer, Methylation, Phosphodiesterase 4C, Risk