Estrogen mediated expression of nucleophosmin 1 in human endometrial carcinoma clinical stages through estrogen receptor-α signaling

BACKGROUND: Endometrial carcinoma is one of the most common gynecologic malignancies. Estrogen plays a critical role in its pathogenesis, but the underlying mechanism is not clear. Nucleophosmin 1 (NPM1), a multifunctional protein involved in many cellular activities, has been implicated in the tumorigenesis processes. However, the role of NPM1 in endometrial carcinogenesis remains to be elucidated. The present study was aimed to elucidate the role of NPM1 in different clinical stages of human endometrial carcinoma and the underlying mechanism of NPM1 action. METHODS: The distribution and expression of NPM1 in normal endometrium, FIGO stages I to IV endometrial carcinoma tissues was analyzed using immunohistochemistry, RT-qPCR and Western blotting. The association between NPM1 expression and estrogen and estrogen receptor signaling was investigated in primary-cultured FIGO stage I endometrial adenocarcinoma cells. RESULTS: A strong positive correlation between NPM1 level and the clinical stage and histological grade of endometrial carcinomas was observed. Expression of NPM1 was up-regulated by estrogen in primary-cultured human endometrial adenocarcinoma cells. Furthermore, estrogen increased NPM1 level via estrogen receptor-α (ERα) signaling, nor estrogen receptor-β signaling. CONCLUSIONS: Expression of NPM1 was gradually increased with the increase of clinical stages of endometrial carcinomas. Overexpression of NPM1 may play a role in the effects of estrogen on the malignant progression of endometrioid adenocarcinoma via ERα signaling. These findings may extend our understanding of the oncogenesis of steroid hormone-related cancers and have significance for the diagnosis and treatment of this carcinoma.