LAUSR

Background The ESR 1 gene suffers methylation changes in many types of cancers, including breast cancer (BC), the most frequently diagnosed cancer in women that is also present in men. Methylation at promoter A of ESR 1 is the worse prognosis in terms of overall survival; thus, the early detection, prognostic, and prediction of therapy involve some methylation biomarkers. Methods Therefore, our study aimed to examine the methylation levels at the ESR 1 gene in samples from Mexican BC patients and its possible association with menopausal status. Results We identified a novel 151-bp CpG island in the promoter A of the ESR 1 gene. Interestingly, methylation levels at this CpG island in positive ERα tumors were approximately 50% less than negative ERα or control samples. Furthermore, methylation levels at ESR 1 were associated with menopausal status. In postmenopausal patients, the methylation levels were 1.5-fold higher than in premenopausal patients. Finally, according to tumor malignancy, triple-negative cancer subtypes had higher ESR 1 methylation levels than luminal/HER2+ or luminal A subtypes. Conclusions Our findings suggest that methylation at this novel CpG island might be a promising prognosis marker