Investigating the Role of Fat Mass and Obesity-Associated (FTO) Single Nucleotide Polymorphisms and Methylation in Breast Cancer.

ABSTRACT

Background Fat mass and obesity-associated (FTO) protein is an mRNA demethylase enzyme essential for active genome regulation. The FTO gene codes for a protein that is part of the methylosome complex and has a regulatory role in cancer development. Some studies have shown a relationship between FTO and cancer, where single nucleotide polymorphisms (SNPs) may have some impact on cancer risk. The present study aimed to evaluate the risk of FTO polymorphisms rs9939609, rs1477196, and rs9930506; analyze the methylation status of FTO promoters among Mexican women with breast cancer (BC); and investigate by in silico analysis the methylation status in the region near these polymorphisms. Methods A total of 157 BC patients and 137 healthy controls were genotyped for rs9939609, rs1477196, and rs9930506 FTO polymorphisms by TaqMan SNP Genotyping Assays. Promoter methylation was analyzed by sodium bisulfite and methylation-specific polymerase chain reaction (MSP) for 78 tissue samples. An in silico analysis using The Cancer Genome Atlas Program (TCGA) database was employed to investigate the methylation state in promoter and near polymorphism locations and its relation to survival. Results The AG genotype of FTO rs9930506 was associated with BC protection (P= 0.0025; adjusted OR, 0.27; 95% CI 0.10-0.70). rs9939609 and rs1477196, according to the results of the present study, had no relation to BC. Promoter methylation status assays by MSP revealed no changes in methylation in BC or healthy tissues. Trying to know more about the methylation in promoters and near polymorphisms' relation to survival, we performed an in silico analysis. Bioinformatics analysis showed a correlation between poor survival and methylation near polymorphisms but not with methylation in the promoter region. Conclusions The AG genotype rs9930506 has a protective function against BC. Whereas high methylation near polymorphisms was related to lower survival, the hypomethylated promoter region does not impact survival.