Short-hairpin RNA-mediated suppression of cortactin may inhibit the migration and invasion abilities of endometrial cancer cells by reducing lamellipodia 

Background: Endometrial cancer (EC) is one of the most common gynecological tumors. The prognosis of EC is seriously affected by the degree of tissue infiltration and distant metastasis by tumor cells. Approximately 15–20% of patients are at high risk of distant metastasis, which carries a poor prognosis. Lamellipodia are related to the invasion and migration of tumor cells, and cortactin (CTTN) can regulate the formation of lamellipodia. Methods Quantitative PCR (qPCR) and immunohistochemical staining (IHC) were used to detect the mRNA and protein of Ras-associated C3 botulinum toxin substrate 1 (Rac1) and CTTN in type I endometrial cancer tissues and normal endometrial tissues. The relationship between the expression of the two genes and the prognostic factors was analyzed. The expression of CTTN in four endometrial cancer cell lines (Ishikawa, AN3CA, HEC-1-A, and HEC-1-B) was detected by quantitative PCR, and the two cell lines with the highest expression levels (HEC-1-A and HEC-1-B) were selected for follow-up study. A CTTN-RNA interference lentiviral system was constructed and transfected into HEC-1-A and HEC-1-B cells. The migration and invasion abilities of the cells in each group were evaluated by scratch assay and transwell migration and invasion assays. Pseudopodia formation was observed using immunofluorescence staining. Western blot was used to detect Rac1 protein expression. Results The mRNA and protein expression of Rac1 and CTTN in EC group were significantly higher than those in normal endometrial group ( P <  0.05). In EC group, there was correlation between the mRNA and protein expression of Rac1 and CTTN. The protein expression of Rac1 was related to lymph-vascular space invasion (LVSI), myometrial invasion and FIGO stage ( P   0.05). The protein expression of CTTN was related to myometrial invasion and FIGO stage ( P   0.05). After CTTN knockdown, the migration rate, invasion ability, and migration ability of HEC-1-A and HEC-1-B cells decreased significantly. A decrease in the number of lamellipodia, accompanied by a compensatory increase in the number of blebs, was also observed. Rac1 protein expression also decreased after CTTN knockdown. Conclusion CTTN may promote the invasion and migration abilities of EC by increasing the number of lamellipodia. This effect may be related to the regulation of Rac1 by CTTN.