摘要
LRP16 was previously identified as an estrogen-induced gene in breast cancer cells. The responsiveness of LRP16 to estrogen and its functional effects in endometrial cancer （EC） cells are still unclear. Here, we show that the mRNA level and promoter activity of the LRP16 gene were significantly increased by 17β-estradiol （E2） in estrogen receptor ot （ERα）-positive Ishikawa human EC cells. Although the growth rate of Ishikawa cells was not obviously affected by ectopic expression of LRP 16, the results of a Transwell assay showed an approximate one-third increase of the invasive capacity ofLRP 16-overexpressing cells. As a result of molecular screening, we observed that the expression of E-cadherin, an essential adhesion molecule associated with tumor metastasis, was repressed by LRP16. Further promoter analyses demonstrated that LRP 16 inhibited E-cadherin transactivation in a dose-dependent manner. However, the inhibition was abolished by estrogen deprivation, indicating that the downregulation of E-cadherin transcription by LRP16 requires ERα mediation. Chromatin immunoprecipitation analyses revealed that the binding of ERα to the E-cadherin promoter was antagonized by LRP 16, suggesting that LRP 16 could interfere with ERα-mediated transcription. These results suggest that the upregulation of LRP 16 by estrogen could be involved in invasive growth by downregulating E-cadherin in human ECs.
基金
We sincerely thank Dr Pudi Renuka and Dr Jianjun Zhou at the National Cancer Institute for their critical reading of our manuscript. We thank Dr Eric R Fearon at the University of Michigan in USA for the E-cadherin promoter reporters and Dr Nowata at Kyushu University of Japan for the ERα expression vector. This work was supported by the National Natural Science Foundation of China （30471813, 30572096 and 30670809）, the Beijing Natural Science Foundation of China （5052024 and 7052061） and the Chinese PLANational Science Fund for Distinguished Young Scholars grant （06J017）.
