YAP/TAZ reverse progestin resistance through PI3K-Akt pathway in endometrial carcinoma

Abstract Background: Progestin resistance is a problem for patients with endometrial carcinoma (EC) who require conservative treatment with progestin, and its underlying mechanisms remain unclear. YAP and TAZ (YAP/TAZ), downstream transcription coactivators of Hippo pathway, are highly expressed and induce aggressive phenotypes of EC. However, the role of YAP/TAZ in progestin resistance of EC is still unknown. The aim of this study is to explore the functions and underlying mechanisms of YAP/TAZ in progestin resistance of EC.Methods: The expression of YAP/TAZ in progestin resistant tissues was examined by immunohistochemistry. We developed a stable medroxyprogesterone acetate (MPA) resistant cell line (IshikawaPR cell). We knocked down YAP/TAZ in IshikawaPR cell, and overexpressed them in progestin sensitive Ishikawa cell for further studies. The proliferative capacity of cell was investigated by MTT, EDU and colony formation assay. Flow cytometry was used to detect the change of cell apoptosis. Transwell and wound healing assay were used to determine the change of cell metastasis ability after different concentrations of MPA treatment. The tumor xenograft experiment was performed to prove the role of YAP/TAZ inhibitor Verteporfin in progestin treatment. The next-generation sequencing (NGS) and rescue experiments were carried out to identify the mechanism involved in the process that YAP/TAZ promote progestin resistance. Results: The expression of YAP/TAZ increased remarkably in progestin resistant tissues. YAP/TAZ were upregutated in IshikawaPR cell versus Ishikawa cell. Knocking down YAP/TAZ decreased cell viability, inhibited cell migration and invasion and increased the sensitivity of IshikawaPR cell to progestin. Overexpression of YAP/TAZ conversely increased cell proliferation, metastasis and promoted progestin resistance. Verteporfin could increase sensitivity of IshikawaPR cell to progestin in vivo and in vitro. Results of the NGS revealed that knocking down YAP/TAZ inhibited PI3K-Akt pathway, which was testified by western blot. The rescue experiments further confirmed overexpression of YAP/TAZ might take part in progestin resistance of EC by upregulating PI3K-Akt pathway. Conclusions: YAP/TAZ as well as Verteporfin could reverse progestin resistance by regulating PI3K-Akt pathway in EC, which may provide ideas for clinical targeted therapy of progestin resistance.