Expression Of X-linked Inhibitor Of Apoptosis Protein In Epithelial Ovarian Carcinoma And Role Of It In Chemoresistance

Aims:1. To detect the expression of XIAP in normal ovaries, benign ovarian tumors and epithelial ovarian carcinomas, and study how XIAP plays an important role in the occurrence and the progression of ovarian carcinoma.2. To detect the expression of XIAP in epithelial ovarian carcinoma cell lines of ES2 and 3AO.3. An eukaryotic expressing vector pcD3/HA-XIAP was constructed and transfected into ES2 cell line with lipofectin to enhance the expression of XIAP's BIR domains. The survival rate of transfected and non-transfected cancer cells were tested to assess the important role XIAP plays in chemoresistance.Methods:1. The representative paraffin sections were selected and 10 specimens of normal ovaries, 30 specimens of benign ovarian tumors and 41 specimens of epithelial ovarian carcinomas were tested by immunohistochemical techinca with antibodyagainst XIAP.2. To observe the expression of XIAP in epithelial ovarian carcinoma cell lines of ES2 and 3AO by Immunocytochemistry and RT-PCR.3. By recombinant DNA technology, the aim genes on pcD3/HA-XIAP were recombined and a fragment of XIAP encompassing the three tandem BIR domains was tranfected to the ovarian carcinoma cells ES2 to increase the protein levels, then screened for obtaining the positive clones.4. To mesure the expression of XIAP in the transfected and non-transfected cancer cells by Western blot. And after treated with cisplatin , the invitro cellulargrowth activitise were estimated by MTT colorimetry. Results:1. The absence of XIAP staining in normal ovaries has been demonstrated. And the expression of XIAP in epithelial ovarian carcinomas was significantly higher than its in benign ovarian tumors( x2=3.9623,P <0.05). In epithelial ovarian carcinomas, the expression of XIAP was markedly increased during progression from early to advanced tumour clinical stages(F=4.261, PO.05). XIAP level was significantly higher in D-D stage than D-D stage(t=2.861,PO.05). But it did not significantly change between low and high tumour histological grades and the different pathological type(P>0.05).2. The patients with higher expression of XIAP had unfavourable prognosis than those with lower or negative expression(Log—rank ^9h11[=4.92, P = 0.0266).3. XIAP mRNA was detected in ovarian carcinoma cell lines (3ACK ES2) by RT-PCR and XIAP was found in cytoplasms of ovarian cell lines by immunochemistry.4. A recombinant plasmid vector pcD3/HA-XIAP encompassing the three tandem BIR genes was constructed successfully.5. After transfected ES2 ovarian carcinoma cell lines, it can be observed that the expression of XIAP's BIR domains was upregulated and influenza virus hemagglutinin tag also can be found by Western blot. After treated with cisplatin 24 hours, as compared with the non-transfeted ES2 cancer cells, the survival rate of transfected ES2 cells was markedly increased(t=3.296, P=0.013). But there were no significantly difference in the one treated cisplatin 48 hours or 72 hours(P>0.05).Conclusion:In epithelial ovarian carcinomas tissue and the two human epithelial ovarian carcinoma cell lines, the expression of XIAP are abundant. The localization of XIAP is in the proliferative epithelial cells. The high level of XIAP is the poor prognostic factor in epithelial ovarian carcinomas. XIAP plays an important role in the occurrence and the progression of ovarian carcinoma.To compare with the higher expression of XIAP and the lower or negative expression of XIAP patients who received chemotherapy after surgery, we can concluded that higher expression patients have a higher relapse rate than lower or negative expression patients. XIAP may be an important factor to promote the chemoresistance in ovarian carcinoma.Upregulating the expression of XIAP BIR domains in epithelial ovarian carcinoma cell lines in vitro could strengthen the tolerance of cancer cells to cisplatin. XIAP could be a potential target for overcoming chemoresistance. It may be a point of regulation for cisplatin in the induction of apoptosis and could be a mechanism of multidrug resistant ovarian carcinoma.