The Expression Of COX-2 In Human Epithelial Ovarian Carcinoma And The Selective Effect Of BAX Gene Driven By COX-2 Promoter In Ovarian Cancer Cell Line

OBJECTIVES: To explore the role of COX-2 in the generation and progression of epithelial ovarian neoplasm and the correlation between the COX-2 expression levels and the clinical pathologic parameters of the tumor tissues through examining the expression of COX-2 in human epithelial ovarian neoplasm tissues and ovarian carcinoma cell lines. Moreover, to verify the value of the COX-2 promoter in gene therapy of ovarian cancer through transfection tests in vitro using the recombination plasmids contained COX-2 promoter drivening pro-apoptosis BAX gene.METHODS: (1) Immunohistochemical staining (SP) was used to detect the expression of COX-2 protein in the paraffine slice of 118 primary ovarian epithelial neoplasm tissues and in S kinds of ovarian carcinoma cell lines. Furthermore, the relationship between COX-2 expression levels and the clinical pathologic parameters was analyzed in ovarian serous cystadenocarcinoma tissues. ( 2 ) The recombinant plasmids named COX-2-BAX and CMV-Luc were constructed by molecular cloning technique and identified by enzyme digestion. (3 ) COX-2-positive ovarian cancer cell line - SKOV3 and COX-2-negative colon cancer cell line-SW480 were transfected liposome-mediated with the recombinant plasmids COX-2-Luc and CMV-Luc , respectively. Luciferase Assay System was used to measure the expression of Luciferase reporter gene. (4) SKOV-3 and SW480 were transfected with C0X-2-BAX and CMV-BAX, respectively. Flow cytometrywas used to measure their apoptosis-inducing effectRESULTS: (1) The positive rates of COX-2 expression in malignant, borderline and benign ovarian epithelial neoplasm were 44% (37/84 ), 32%(6/19) and 0% (0/15) , respectively. The expressions of COX-2 had significant difference(P=0.006) in different ovarian epithelial neoplasm. (2 ) The COX-2 expressions had no correlation to FIGO stage and tumor grade( P=0.716 . and P=0.700, respectively ) in 68 ovarian serous cystadenocarcinoma tissues. (3) COX-2 protein expression could be observed in 4/5 ovarian cancer cell lines examined. (4) The recombinant plasmids named COX-2-BAX and CMV-Luc were constructed successfully and identified by DNA sequencing and enzyme digestion. ( 5 ) The expression efficiency of luciferase reporter gene was 1554+86.5 in SKOV3 and 53.7+ 10.9 in SW480 after 24 hours transfected with COX-2-Luc, 9851.7+129.5 in SKOV3 and 8831.0 +167.3 in SW480 after 24 hours transfected with CMV-Luc, respectively. But in the same cell line, the efficiency of CMV promoter is 6.3 times (in SKOV3) and 164.5 times (SW480) of COX-2 promoter's. (6) The apoptosis rate was 10.4% in SKOV3 and 3.7% in SW480 after 36 hours transfected with COX-2-BAX, 21.7% in SKOV3 and 25.6% in SW480 after 36 hours transfected with CMV -BAX.CONCLUSION: ( 1 ) The expression of COX-2 is obviously up-regulated in epithelial ovarian carcinoma. (2) There is no significant correlation between COX-2 expression and clinical pathologic parameters in ovarian serous cystadenocarcinoma. (3) COX-2 promoter is partial tumor specific, but its transcription efficiency was lower than CMV promoter's. With proper modification, COX-2 promoter is useful in gene therapy of ovarian cancers.