Yifei Yin1,2, Shuifang Lei1, Lixi Li3, Xiaoqin Yang4, Qiming Yin1, Tian Xu5, Wenjie Zhou6, Hong Li7, Wanjian Gu5, Fei Ma3, Rongxi Yang8, Zhengdong Zhang9,10. 1. Department of Epidemiology and Biostatistics, School of Public Health, Nanjing Medical University, Nanjing, China. 2. Department of Thyroid and Breast Surgery, The Affiliated Huai'an Hospital of Xuzhou Medical University and The Second People's Hospital of Huai'an, Huai'an, China. 3. Department of Medical Oncology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China. 4. Department of Breast Surgery, West China Hospital, Sichuan University, Chengdu, China. 5. Department of Clinical Laboratory, Jiangsu Province Hospital of Chinese Medicine, Nanjing, China. 6. Chengdu Shang Jin Nan Fu Hospital, West China Hospital, Sichuan University, Chengdu, China. 7. Department of Pathology, The Affiliated Huai'an Hospital of Xuzhou Medical University and The Second People's Hospital of Huai'an, Huai'an, China. 8. Department of Epidemiology and Biostatistics, School of Public Health, Nanjing Medical University, Nanjing, China. rongxiyang@njmu.edu.cn. 9. Department of Environmental Genomics, Jiangsu Key Laboratory of Cancer Biomarkers, Prevention and Treatment, Collaborative Innovation Center for Cancer Personalized Medicine, Nanjing Medical University, Nanjing, China. drzdzhang@njmu.edu.cn. 10. Department of Genetic Toxicology, The Key Laboratory of Modern Toxicology of Ministry of Education, Center for Global Health, School of Public Health, Nanjing Medical University, Nanjing, China. drzdzhang@njmu.edu.cn.
Abstract
BACKGROUND: Altered regulatory-associated protein of mTOR, complex 1 (RPTOR) methylation levels in peripheral blood was originally discovered as breast cancer (BC)-associated risk factor in Caucasians. OBJECTIVE: To explore the relationship between RPTOR methylation and BC in the Chinese population, we conducted two independent case-control studies. METHODS: Peripheral blood samples were collected from a total of 333 sporadic BC cases and 378 healthy female controls for the DNA extraction and bisulfite-specific PCR amplification. Mass spectrometry was applied to quantitatively measure the levels of methylation. The logistic regression, Spearman's rank correlation, and Non-parametric tests were used for the statistical analyses. RESULTS: In our study, we found an association between BC and RPTOR_CpG_4 hypomethylation in the general population (per-10% of methylation, OR 1.29, P = 0.012), and a weak association between BC and RPTOR_CpG_8 hypomethylation in the women with older age (per-10% of methylation, OR 2.34, P = 0.006). We also identified age as a confounder for the change of RPTOR methylation patterns, especially at RPTOR_CpG_4, which represented differential methylation comparing age groups especially in the BC cases (age < 50 years vs age ≥ 50 years by Mann-Whitney U test, P < 0.0001 for BC cases and P = 0.079 for controls). CONCLUSION: Our study validated the association between hypomethylation of RPTOR and BC risk in the Chinese population also with weak effect and mostly for postmenopausal women. In addition, our findings provided novel insight for the regulation of DNA methylation upon aging or the change of hormone levels.
BACKGROUND: Altered regulatory-associated protein of mTOR, complex 1 (RPTOR) methylation levels in peripheral blood was originally discovered as breast cancer (BC)-associated risk factor in Caucasians. OBJECTIVE: To explore the relationship between RPTOR methylation and BC in the Chinese population, we conducted two independent case-control studies. METHODS: Peripheral blood samples were collected from a total of 333 sporadic BC cases and 378 healthy female controls for the DNA extraction and bisulfite-specific PCR amplification. Mass spectrometry was applied to quantitatively measure the levels of methylation. The logistic regression, Spearman's rank correlation, and Non-parametric tests were used for the statistical analyses. RESULTS: In our study, we found an association between BC and RPTOR_CpG_4 hypomethylation in the general population (per-10% of methylation, OR 1.29, P = 0.012), and a weak association between BC and RPTOR_CpG_8 hypomethylation in the women with older age (per-10% of methylation, OR 2.34, P = 0.006). We also identified age as a confounder for the change of RPTOR methylation patterns, especially at RPTOR_CpG_4, which represented differential methylation comparing age groups especially in the BC cases (age < 50 years vs age ≥ 50 years by Mann-Whitney U test, P < 0.0001 for BC cases and P = 0.079 for controls). CONCLUSION: Our study validated the association between hypomethylation of RPTOR and BC risk in the Chinese population also with weak effect and mostly for postmenopausal women. In addition, our findings provided novel insight for the regulation of DNA methylation upon aging or the change of hormone levels.