Abstract: Objective To observe the expression of HELQ and RAD51C in normal endometrial and endometrial stromal sarcoma (ESS) and analyze their correlation with the clinical features of the patients. Methods The expressions of HELQ and RAD51C proteins were detected by immunohistochemical staining in normal endometrial tissues (14 cases) and tumor tissues from patients with ESS (37 cases) treated in Hunan Provincial Cancer Hospital from January, 2013 to December, 2016. The correlations of the expressions of the two proteins with the patients’age, FIGO staging, tissue type, tumor size, and lymph node metastasis were analyzed. Results Immunohistochemical staining showed that the expressions of HELQ and RAD51C were both decreased in ESS patients compared with the normal group, and there was a positive correlation between HELQ and RAD51C expression (P<0.05). HELQ expression in ESS was correlated with the tumor size and type. The expressions of HELQ and RAD51C were not correlated with the patients’ age, FIGO stage and status of lymph node metastasis (P>0.05). Conclusion Homologous recombination- directed DNA repair involving HELQ and RAD51C may participate in the occurrence and progression of ESS.

Key words: endometrial stromal sarcoma, HELQ, RAD51C, DNA damage repair