Sunitinib induces primary ectopic endometrial cell apoptosis through up‐regulation of STAT1 in vitro

BACKGROUND: Endometriosis (EMS) is a prevalent gynecological condition characterized by the growth of endometrial tissue outside the uterine cavity. This study aimed to clarify the targeted therapeutic effect of sunitinib in an endometriosis in vitro experiment. METHODS: Primary culture of ectopic endometrial cells and normal endometrial cells. Six tumor targeting drugs were selected to screen. MTT was used to determine the IC50, flow cytometry, and DAPI staining of the targeted drugs, in order to determine the apoptosis. The differential proteins after seeding were analyzed by protein spectrum, the correlation between the specific protein and cell apoptosis was determined by small molecule interference, and the expression of each related protein was detected by Western blot. Immunohistochemistry and ELISA were used to detect the expression of p‐PDGFR and p‐STAT1 in clinical samples, and the correlation between p‐STAT1 expression and ectopic focal size was analyzed by SPSS 19. RESULTS: Through the drug screening, it was found that sunitinib has a significant inhibitory effect on ectopic endometrial cells. It was determined that the IC50 of sunitinib on ectopic stromal endometrial cells was 3.32 μM, while the IC50 on normal endometrium was 7.9 μM. Meanwhile, the flow cytometry and DAPI nuclear dye that took out sunitinib had an inhibition effect on the ectopic endometrium at a concentration of 4 μM. Protein spectrum analysis was conducted on ectopic intimal cells after sunitinib treatment, and it was found that STAT1 is specifically expressed in ectopic endometrial cells. In vitro, and through fludarabine interference, it was revealed that sunitinib specifically inhibited the phosphorylation site Tyr751 of PDGFR, while the expression of STAT1, p‐STAT1, and caspase‐3 was significantly upregulated, and the expression of STAT1 and p‐STAT1 was positively correlated with the expression of caspase‐3. Finally, the expression of p‐PDGFR and p‐STAT1 in ectopic foal tissues was both higher than that in normal endometrium, and p‐STAT1 expression was positively with ectopic focal size. CONCLUSION: The in vitro experiments revealed that sunitinib could upregulate the expression of STAT1 by inhibiting the phosphorylation site Tyr751 of PDGFR, thereby specifically inducing the apoptosis of the primary heterotopic mesenchymal endometrium.