Expression of a Novel 90 kDa Heat Shock Protein in Colorectal Tumor

ABSTRACT

PURPOSE: When cells are subjected to a wide variety of stressful stimuli, they respond by increasing the synthesis of specific stress proteins. Stresses include heat shock, nutrient deprivation, oxygen radicals, toxic metal and viral infection. Major stress proteins are Hsp 27, Hsp 60, Hsp 70 (9), Hsp 90 (3) and Hsp 100 (1). Previously a novel 90 kDa stress protein has been reported to be induced in fish cells by virus infection. The novel 90 kDa stress protein is different from well-known major stress protein in size, antigenicity, cellular localization. The novel 90 kDa stress protein was found to be present in various kinds of cells including human cells and its expression was increased in human carcinomas. The purpose of this study is to evaluate the expression of the novel 90 kDa stress protein in human colonic mucosa of normal tissue, adenoma and adenocarcinoma using immunohistochemical method. METHODS: 85 colon tissues were screened for the expression of the novel 90 kDa stress protein; 85 normal colonic mucosa, 20 colonic adenoma and 65 colonic adenocarcinoma. The tissues were stained with monoclonal antibody against the novel 90 kDa stress protein. In scoring system, tissue sections with immunostained area above 10 % were decided to be positive and, among the positive, the tissue sections were divided into three score, 1, 2, and 3, based on the staining intensity and positive area proportion. The tissue sections with immunostained area below 10% were decided to be negative and grouped into 0 score. Correlation of immunohistochemical expression was analysed by using SPSS version 10.0 statistically. RESULTS: The expression of the 90 kDa stress protein was significantly different among normal colonic mucosa, colonic adenoma, and colonic adenocarcinoma and the percentage of positive samples were 14.1%, 80.5%, and 95.4% respectively. This result suggests that the expression level of the novel 90 kDa stress protein was extremely low in normal tissue but increased significantly in adenocarcinomatous tissues. CONCLUSIONS: The expression of the novel 90 kDa stress protein was increased significantly with transformation of the normal colon tissue to malignancy. This suggests the possibility that this novel 90 kDa stress protein play some role in cancerous transformation of colon tissue.