Clinical implications of mRNA expression of KAI1 in ovarian cancer with or without metastasis

Background. KAI1 is a potential metastasis suppressor gene for prostate cancer. Decreased expression of KAI1 mRNA has been shown to be associated with the formation of metastasis and the progression of prostate, lung, breast, pancreatic, and bladder cancer. It has also been reported, however, that KAI1 expression is unchanged in metastatic and nonmetastatic esophageal and gastric cancer. We performed the present study to investigate the function of KAI1 in the progression and/or metastasis of ovarian cancer. Methods. We investigated the mRNA expression levels of the KAI1 gene, using quantitative polymerase chain reaction (PCR), in 29 ovarian tumors (1 adenoma, 2 low- malignant potential tumors, 9 adenocarcinomas without metastasis, and 17 adenocarcinomas with metastasis), seven ovarian cancer cell lines, and two normal ovaries. Using a thermal cycler, we found that the KAI1 gene was amplified in parallel with an internal control gene, β-Actin. The relative expression ratio (KAI1/β-Actin) as measured by densitometry was used to evaluate gene expression. Immunohistochemical localization of the KAI1 protein in ovarian cancer tissues was confirmed by the avidin-biotin peroxidase complex (ABC) method. Results. The mRNA expression levels of KAI1 were consistent in normal ovary, ovarian tumor samples, and ovarian cancer cell lines. No statistically significant difference in the KAI1 mRNA expression level was found in ovarian cancer samples with or without metastasis. Immunohistochemistry revealed that the KAI1 protein was expressed in the cell membranes of ovarian cancer cells. Conclusions. Our results suggest that reductions in KAI1 mRNA expression are not involved in either the progression or metastasis of ovarian carcinomas. Received: April 22, 1999 / Accepted: July 26, 1999