RESUMEN
PURPOSE: When cells are subjected to stressful stimuli such as, heat shock, toxic metal, nutrient deprivation, and metabolic disruption, they increase production of specific stress proteins that buffer them from harm. We reported that the expression of a navel 90 kDa cellular protein was increased by the infection of a fish rhabdovirus and heat shock in a fish cell. This new 90 kDa protein is not expressed in normal animal tissues but is highly induced in progressively transforming tissues or cells. That gives us some ideas tl at it is possible for this stress protein to be expressed in specific human cancer tissues. MATERIALS AND METHODS: Commercialized checkerboard multi-tumor block (DAKO Co. Carpinteria, CA) was used for immunohistochemical analysis. The samples of human gastric cancer, colon cancer and breast cancer tissues were evaluated by Western blot and Northern blot for overexpression of the novel 90 kDa stress protein. Sera of those patients were analyzed by ELISA for the presence of antibody against the novel 90 kDa stress protein. RESULTS: Immunohistochemical staining of human tumor tissue blocks showed significant immunostaining of novel 90 kDa stress protein in carcinomas such as colon cancer, breast cancer and stomach cancer but no apparent immunostaining in sarcomas. Coinciding with the immunohistochemical result, Western blotting and Northern blotting analyses indicate that the expression of the novel 90 kDa stress protein was increased in carcinomas. In addition, the antibody titer against the novel 90 kDa stress protein was found to be elevated in the sera of cancer patients. CONCLUSIONS: The novel 90 kDa stress protein gene expression was elevated in carcinomas such as gastric cancer, breast cancer and colon cancer. These findings suggest that this new stress protein can be used as a tumor marker and may function as a chaperone in tumor growth.