Expression of ER-α36, a novel variant of estrogen receptor in endometrial carcinoma and its clinical significance.

OBJECTIVE

Estrogen receptor-α36 (ER-α36), a newly identified variant of ER-α, is predominantly membrane-based and mainly mediates nongenomic estrogen signaling. In this study, we investigated the expression of ER-α36 in human endometrial carcinoma tissues to understand the relationship between its expression and clinicopathological characteristics.

METHODS

ER-α36 expression was assessed by immunostaining in 73 endometrial carcinomas, 20 normal endometrial tissues, and 9 with atypical endometrial hyperplasia. Correlations between ER-α36 protein expression and clinicopathological characteristics were investigated.

RESULTS

The expression of ER-α36 in endometrial carcinoma tissues was significantly lower than in normal endometrial tissues and atypical hyperplasia (p < 0.01). ER-α36-negative tissues were significantly more likely than ER-α36-positive tumors to have tumor involvement of the cervix (p < 0.05). The disease-free survival rate of patients with ER-α36 expression was poorer than that of those who were negative for ER-α36 expression (p < 0.01). There was no significant relationship between ER-α36 expression and patient age, surgical staging, histological differentiation, myometrial invasion, lymph node metastasis, and pathological types (p > 0.05).

CONCLUSIONS

ER-α36 may be an important biomarker for diagnosis, prognostication, and treatment choice in endometrial carcinoma.