Heat shock proteins are differentially expressed in human gastrointestinal cancers.

The heat shock proteins (Hsp) are stress-responsive genes present in all species; increases of Hsp can confer chemotherapeutic resistance to certain cancers. The purpose of this study was to determine Hsp expression in human gastric, pancreatic and colon cancers. Gastric (n = 3), pancreatic (n = 6) and colon (n = 8) cancers were extracted for RNA and protein, and Northern and Western blots performed. We found that hsp70 and hsp27 mRNA levels were differentially expressed in the gastrointestinal cancers; mRNA expression closely correlated with protein levels suggesting regulation at the level of transcription. In addition, Hsp90 and BiP proteins were constitutively expressed in the gastrointestinal cancers. We conclude that the Hsp are differentially expressed in human gastric, pancreatic and colon cancers; these increases in Hsp occur constitutively and are not the result of physiological or environmental stresses. Increases of Hsp expression in cancer cells may enhance resistance and account for the altered sensitivity of certain gastrointestinal cancers to chemotherapeutic agents.