FOXA1 promotes tumor cell proliferation through AR involving the Notch pathway in endometrial cancer

Meiting Qiu,Xiaoying He,Yun Liao,Wei Bao,Jingyun Wang,Xiaoping Wan,Tingting Yang

doi:10.1186/1471-2407-14-78

Abstract

BackgroundIncreasing evidence suggests that forkhead box A1 (FOXA1) is frequently dysregulated in many types of human cancers. However, the exact function and mechanism of FOXA1 in human endometrial cancer (EC) remains unclear.MethodsFOXA1 expression, androgen receptor (AR) expression, and the relationships of these two markers with clinicopathological factors were determined by immunohistochemistry analysis. FOXA1 and AR were up-regulated by transient transfection with plasmids, and were down-regulated by transfection with siRNA or short hairpin RNA (shRNA). The effects of FOXA1 depletion and FOXA1 overexpression on AR-mediated transcription as well as Notch pathway and their impact on EC cell proliferation were examined by qRT-PCR, western blotting, co-immunoprecipitation, ChIP-PCR, MTT, colony-formation, and xenograft tumor–formation assays.ResultsWe found that the expression of FOXA1 and AR in ECs was significantly higher than that in a typical hyperplasia and normal tissues. FOXA1 expression was significantly correlated with AR expression in clinical tissues. High FOXA1 levels positively correlated with pathological grade and depth of myometrial invasion in EC. High AR levels also positively correlated with pathological grade in EC. Moreover, the expression of XBP1, MYC, ZBTB16, and UHRF1, which are downstream targets of AR, was promoted by FOXA1 up-regulation or inhibited by FOXA1 down-regulation. Co-immunoprecipitation showed that FOXA1 interacted with AR in EC cells. ChIP-PCR assays showed that FOXA1 and AR could directly bind to the promoter and enhancer regions upstream of MYC. Mechanistic investigation revealed that over-expression of Notch1 and Hes1 proteins by FOXA1 could be reversed by AR depletion. In addition, we showed that down-regulation of AR attenuated FOXA1-up-regulated cell proliferation. However, AR didn’t influence the promotion effect of FOXA1 on cell migration and invasion. In vivo xenograft model, FOXA1 knockdown reduced the rate of tumor growth.ConclusionsThese results suggest that FOXA1 promotes cell proliferation by AR and activates Notch pathway. It indicated that FOXA1 and AR may serve as potential gene therapy in EC.

Highlights

Increasing evidence suggests that forkhead box A1 (FOXA1) is frequently dysregulated in many types of human cancers
The results showed that FOXA1 expression correlated positively with androgen receptor (AR) expression (p = 0.003) (Table 2)
These results suggested that FOXA1 expression, which correlated with AR expression, had a connection with the development of endometrial cancer (EC) and risk-associated clinical features of the disease

Summary

Introduction

Increasing evidence suggests that forkhead box A1 (FOXA1) is frequently dysregulated in many types of human cancers. The exact function and mechanism of FOXA1 in human endometrial cancer (EC) remains unclear. Endometrial cancer (EC) is one of the most common gynecologic malignancies. EC is broadly classified into two groups [1]; type I ECs are linked to estrogen excess, hormone-receptor positivity, and favorable prognoses, whereas type II, primarily serous tumors, are more common in older women and have poorer outcomes [2]. Endocrine treatment, including medroxyprogesterone acetate or tamoxifen, is sometimes useful to improve the outcome. Patients with type II EC and even some patients with type I EC are refractory to traditional endocrine treatment [3]. A new treatment is needed to achieve a better response

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Conclusion