To explore the correlation of abnormal expression of X-linked inhibitor of apoptosis protein (XIAP) and XIAP associated factor (XAF)1 with ovarian cancer.

A total of 72 patients diagnosed with ovarian cancer based on postoperative histopathological examination following comprehensive staging surgery in the Department of Gynecology, West China Second University Hospital, Sichuan University from June to December 2018 were selected as subjects, and were included into ovarian cancer group. Based on results of histopathological examination, they were further divided into moderately and well-differentiated subgroup (n=24) and poorly differentiated subgroup (n=48), serous carcinoma subgroup (n=36) and non-serous carcinoma subgroup (n=36); according to the International Federation of Gynecology and Obstetrics (FIGO) clinical staging, they were further divided into stage Ⅰ-Ⅱ subgroup (n=35) and stage Ⅲ-Ⅳ subgroup (n=37), without lymph node metastasis subgroup (n=59) and lymph node metastasis subgroup (n=13). And 35 ovarian benign tumor patients who underwent unilateral ovarian cystectomy for ovarian teratoma, ovarian cyst, and so on in the same hospital during the same period and were histopathologically diagnosed with benign ovarian tumors postoperatively, were included into benign tumor group. And 30 patients who underwent total hysterectomy with bilateral salpingo-oophorectomy for adenomyosis and uterine fibroids and were histopathologically diagnosed with adenomyosis and uterine fibroids, while maintaining normal ovarian function, were included into normal control group. Immunohistochemistry (IHC) was used to detect the expression of XIAP and XAF1 in surgically excised ovarian tissues of three groups. Chi-square test were conducted for comparison of positive expression rates of XIAP and XAF1 in surgically excised ovarian tissue among three groups. Spearman′s rank correlation analysis was used to analyze the correlation between XAF1 and XIAP expression in patients of ovarian cancer group. There were no statistical differences among three groups in general clinical data, such as age and so on (P>0.05). The procedures followed in this study were in accordance with the requirements of World Medical Association Declaration of Helsinki revised in 2013.

①The positive expression rates of XIAP in ovarian tissue of ovarian cancer group, benign tumor group and normal control group were 81.3% (60/72), 51.4% (18/35), 46.7% (14/30), respectively, and XAF1 positive expression rates were 38.9% (28/72), 80.0% (28/35), 86.7% (26/30), respectively. There were statistically significant differences in overall comparison of positive expression rates of XIAP and XAF1 in ovarian tissue of three groups (χ²=18.12, 28.06; P<0.001). Further pairwise comparisons revealed that the positive expression rate of XIAP in ovarian tissue of ovarian cancer group was significantly higher than that in benign tumor group and normal control group, while the positive expression rate of XAF1 in ovarian tissue of ovarian cancer group was significantly lower than that in benign tumor group and normal control group, and all the differences were statistically significant (P all <0.001). However, there were no statistically significant differences in positive expression rates of XIAP and XAF1 in ovarian tissue of benign tumor group and normal control group (P=0.072, 0.475). ②The positive expression rates of XIAP in ovarian tissue of ovarian cancer patients in poorly differentiated subgroup, Ⅰ-Ⅱ subgroup and without lymph node metastasis subgroup were 91.7% (44/48), 51.4% (18/35) and 45.8% (27/59) respectively, which all were significantly higher than a rate of 66.7% (16/24) in moderately and well-differentiated subgroup, 27.0% (10/37) in Ⅲ-Ⅳ subgroup, and 7.7% (1/13) in lymph node metastasis subgroup (χ²=7.20, 4.51, 6.50; P=0.007, 0.034, 0.011). ③In ovarian tissue of serous carcinoma subgroup and non-serous carcinoma subgroup, there were no statistically significant differences in correlation between positive expression intensities of XIAP and XAF1 (r_s=-0.315, 0.094; P=0.585, 0.062).

Compared to normal ovarian tissue and benign ovarian tumor tissue, ovarian cancer tissue exhibits decreased expression of XAF1 and increased expression of XIAP. Among ovarian cancer patients, expression of XIAP in ovarian cancer tissue is associated with the differentiation degree of ovarian cancer tissue, while expression of XAF1 is related to FIGO clinical stage and lymph node metastasis. The correlation between XIAP and XAF1 in ovarian cancer patients needs to be confirmed by further studies.