Evaluation of Methylation Panel in the Promoter Region of p16INK4a , RASSF1A, and MGMT as a Biomarker in Sputum for Lung Cancer

Lung cancer is the most common cause of cancer death in the world. Effective early detection and appropriate medications can help treat this deadly cancer. Therefore, early detection of lung cancer is of utmost importance, especially in screening high-risk populations (such as smokers) with an urgent need to identify new biomarkers. The present study aimed to demonstrate the potential of using the panel of DNA methylation as a biomarker for the early diagnosis of lung cancer from sputum samples. The methylated promoter of p16^INK4a , RASSF1A, and MGMT genes was estimated by the methylation-specific polymerase chain reaction in a sample of 84 lung cancer patients (65 smokers and 19 non-smokers). Based on the results, p16^INK4a promoter methylation was significantly associated with smoking habit and lung cancer progression in terms of histological grading and patient staging. The sensitivity and specificity of the p16^INK4a gene as a biomarker for lung cancer were 71% and 90%, respectively. The methylated promoter of RASSF1A was less sensitive (48%) as a biomarker for lung cancer with 83%. The results demonstrated a strong association between promoter methylation of RASSF1A and late stages of lung cancer (P=0.0007). The sensitivity of the MGMT gene as a biomarker for lung cancer was 61% with high specificity (92%), compared to other candidate genes in this study. The epigenetic alteration in the promoter region of p16^INK4a , RASSF1A, and MGMT genes is highly associated with cancer cell development. It is suggested that the use of these candidate biomarkers can be used as an adjunct to computed tomography screening to diagnose patients at high risk for lung cancer after validation.

[Epigenetic mechanism of obesity-induced male infertility]

Epigenetic changes induced by obesity can lead to male infertility phenotype. As for the relationship between obesity and male infertility, early studies mostly focused on the endocrine aspect. Recent studies have found that obesity can cause epigenetic changes, such as DNA methylation, residual histone modification, small RNA, etc, affecting sperm maturation and development. DNA methylation is a regulatory marker on cytosine residue of cytosine-phosphate-guanine dinucleotide. Obesity leads to abnormal DNA methylation, changes mRNA expression abundance, affects imprinted gene expression induses imprinted gene diseases. The modification methods of residual histones include methylation, acetylation, etc. They can interact or cooperate to ensure the normal growth and development of sperm. Obesity changes methylase and acetylase activities and directly affects methylation and acetylation of residual histones, and the expression of micro-RNAs in sperm as well, consequently causing sperm defects. This article reviews epigenetic changes caused by obesity and the mechanism of male infertility.