CpG island methylation profile of estrogen receptor alpha in iranian females with triple negative or non-triple negative breast cancer: New marker of poor prognosis

One decade early onset of the breast cancer in Iranian females was reported but the basis of the observed
difference has remained unclear and difference in gene silencing by epigenetic processes is suggested. Hence,
this study was sought to map the methylation status of estrogen receptor (ER) gene CpG islands and its impact
on clinicopathological factors of triple negative and non-triple negative ductal cell carcinoma of the breast
in Iranian females. Surgically resected formalin-fixed paraffin-embedded breast tissues from sixty Iranian
women with confirmed invasive ductal carcinoma were assessed by methylation-specific PCR using primer sets
encompassing some of the 29 CpGs across the ER gene CpG island. The estrogen and progesterone receptors,
Her-2+ overexpression, and nuclear accumulation of P53 were examined using immunohistochemistry (IHC).
Methylated ER3, ER4, and ER5 were found in 41.7, 11.3, and 43.3% of the samples, respectively. Significantly
higher methylation of ER4 was found in the tumors with nuclear accumulation of P53, and significantly higher
methylation of ER5 was found in patients with lymph node involvement and tumor with bigger size or higher
grades. Furthermore, significantly higher rate of ER5 methylation was found in patients with Her-2+ tumors
and in postmenopausal patients with ER¯, PgR¯, or ER¯/PgR¯ tumors. However, no significant difference in ERs
methylation status was found between triple negative and non-triple negative tumors in pre- and postmenopausal
patients. Findings revealed that aberrant hypermethylation of the ER-alpha gene frequently occurs in Iranian
women with invasive ductal cell carcinoma of the breast. However, methylation of different CpG islands produced
a diverse impact on the prognosis of breast cancer, and ER5 was found to be the most frequently methylated
region in the Iranian women, and could serve as a marker of poor prognosis.