LAUSR

Progestin resistance limits the effectiveness of progestin therapy in endometrial carcinoma for patients who desire to preserve fertility. To investigate the molecular mechanism of progestin resistance in endometrial carcinoma, we performed microarray analysis among Ishikawa and progestin resistant cell IshikawaPR cells. We found that epithelial to mesenchymal transition (EMT) was involved in progestin resistance and dachshund family transcription factor 1 (DACH1) is positively correlated with progesterone receptor (PGR). Knockdown of DACH1 in Ishikawa cell promoted proliferation, metastasis ability, and resistance to progestin. Conversely, overexpression of DACH1 in IshikawaPR cell rendered more sensitive to progestin treatment. Xenograft model assay also had similar results. In addition, our data showed that DACH1 overexpression inhibited EMT and decreased c‐Jun, Notch1 and Hes1expression. Our study demonstrated for the first time that EMT is involved in progestin resistance of EC. The response to progestin could be reserved by DACH1 suppressed EMT through Notch1 pathway via c‐Jun.