Overexpression of heat shock protein (hsp) 70 associated with abnormal p53 expression in cancer of the pancreas.

Heat shock proteins (hsp) are involved in degradation or chaperoning nascent and abnormal proteins to various subcellular locations. p53 tumour suppressor gene overexpression and mutation occur frequently in pancreatic cancers. Mutant p53 proteins produced in cancers of other sites have been found to form complexes with hsp 70. Consequently, binding to hsp 70 may be used to indicate the presence of mutant p53 proteins. The presence of hsp 70 was investigated by immunohistochemistry in core biopsies of 42 adenocarcinomas of the pancreas (well differentiated, N = 1 and moderate to poorly differentiated, N = 41). Four cases of islet cell tumours were included in the study. These neoplasias were compared with biopsies of chronic pancreatitis (N = 9) and normal pancreas (N = 5). The majority of adenocarcinomas, 24/42 (57%), showed expression of both hsp 70 and p53. None of the islet cell tumours or cases of chronic pancreatitis showed p53 and hsp 70 coexpression. Only 1 (20%) of the normal pancreas showed concurrent nuclear immunostaining for p53 and cytoplasmic immunostaining for hsp 70. The high proportion of pancreatic adenocarcinoma showing immunoreactivity for both hsp 70 and p53 may indicate high mutation rate of the p53 gene in this tumour. Further studies using molecular techniques are required to elucidate the nature of both hsp and p53 genes in pancreatic cancers.