Methylation of the ESR1 promoters in visceral adipose tissue and its relationship with obesity.

Background: Obesity is associated with decreased ESR1 expression level in visceral adipose tissue. However, it is unclear exactly what mechanisms are responsible for this decline. The aim of this study was to investigate the impact of aberrant methylation of the ESR1 alternative promoters on decreased ESR1 expression and its connection to obesity.

Methods: Visceral adipose tissues and peripheral blood cells were obtained from 21 patients (non-obese and obese) undergoing inguinal hernia or gallbladder removal. Alternative promoter regions, C, E2 and F of the ESR1 gene, were analyzed by Methylation-Specific PCR (MSP) and mRNA levels were measured by quantitative real-time PCR (qPCR) in both visceral adipose tissue and peripheral blood cells. All statistical analyses were performed by SPSS (23.0).

Results: The methylation percentage in the three promoter regions of ESR1 was not different in obese individuals compared to non-obese individuals. We observed that promoter C had the highest methylation frequency in obese patients, although it was not statistically significant. Additionally, we observed that the hypermethylation of ESR1's promoter C was significantly associated with lower mRNA expression level in obesity (p = 0.020).

Conclusion: This study suggests that methylation of ESR1 promoter C may be a factor in the development of obesity or a consequence of obesity. Further studies with advanced methods and larger study groups are needed to clarify this issue.