[Study on genetic instability of NM23H1 gene in Chinese with the epithelial ovarian tumor].

Abstract

The aim of this study was to examine microsatellite instability (MSI) and loss of heterozygosity (LOH) of locus D17S396 on chromosome 17 and their influence on the expression of nm23H1 in the epithelial ovarian tumors, which may provide experimental basis for the mechanism of nm23H1 gene and tumor metastasis. Techniques such as DNA extraction from formalin-fixed paraffin-embedded tissues, polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP), ordinary silver stain were used to study MSI and LOH of locus D17S396. Envision immunohistochemistry and Leica-Qwin computer imaging techniques were used to assess the expression of nm23H1 gene. In our experiments, the frequency of heredity instability of malignant ovarian tumors was 40%, which is higher than that of borderline ovarian tumors, while there were no heredity instability occurred in benign ovarian tumors and normal ovarian tissue. Among 25 epithelial ovarian carcinomas, the frequency of LOH in lymph node metastasis cases (66.67%) was significantly higher than those without metastasis (10.53%). Moreover, the frequency of LOH was higher in FIGO stage III and IV than in stage I and II. However, the frequency of MSI showed no correlation with any clinicopathologic characteristics. The positive frequency of nm23H1 protein in the ovarian epithelial carcinoma and borderline tumors were 56.00% and 57.14%, respectively. They were both higher than those of the benign tumors and normal ovarian tissue. In the epithelial ovarian carcinomas, the positive frequency of nm23H1 protein in lymph node metastasis case was significantly lower than those without metastasis. FIGO stage III and IV also exhibited lower positive frequency of nm23H1 protein compared with stage I and II. Furthermore, there was no difference in nm23H1 protein expression intensity analyzed by computer imaging. In the epithelial ovarian carcinomas, the positive frequency of nm23H1 protein in LOH positive group was 0.00%, which is lower than that of LOH negative group (P < 0.01). The results indicated that the heredity instability of nm23H1 gene might be implicated in pathogenesis and progression of epithelial ovarian tumor. The occurrence of LOH might be the molecule marker of the deteriorism of ovarian tissue. Both MSI and LOH of nm23H1 gene controlled development of the epithelial ovarian tumor independently in different paths. LOH could inhibit the expression of nm23H1 in local tissue of the epithelial ovarian carcinoma, which endowed it with high aggressive and poor prognosis. Increasing the amount of nm23H1 protein expression could effectively restrain metastasis of the ovarian epithelial carcinoma and improve prognosis of patients.