Double immunostaining for p53 and molecular chaperone hsp72/73 in gastric carcinoma

Abstract

Aims - To examine the relation between the expression of p53 protein and the chaperone heat shock protein (hsp) 72/73 in a population at high risk for gastric carcinoma, suing single and double immunohistochemistry, and to compare the expression of these two proteins with clinicopathological features. Methods - Monoclonal antibodies were used to investigate the expression of p53 protein and hsp72/73 in 46 human gastric carcinomas. A double immunohistochemistry technique was used in cases that showed p53/hsp72/73 coexpression. Results - p53 immunoreactvity was present in 11 tumours (24%), and hsp72/73 immunostaining was observed in 22 cases (48%). p53 expression was observed as nuclear staining in tumoral cells. hsp72/73 expression was demonstrated mainly as cytoplasmic staining, but six tumours also showed focal weak nuclear staining. Seven cases showed p53 and hsp72/73 coexpression with immunoreactivity for both proteins in the same neoplastic cells, three of them with focal areas of nuclear co-expression. p53 expression was seen more frequently in cases that showed a high intensity (+++) of hsp72/73 staining. No significant association was observed between the expression of the two proteins and clinicopathological features. Conclusions - More than half of our cases may have some impairment in p53 protein growth suppressive function, as a result of p53 gene alterations or complex formation. The positive correlation between p53 expression and intensity of hsp72/73 supports the postulate of a p53 regulating function for the chaperone hsp72/73. A high intensity of hsp72/73 immunohistochemical staining could be used as an indirect marker of p53 gene abnormalities.