Heat-Shock Protein 70 and p53 Protein Expression in Gastric Carcinomas

ABSTRACT

Gastric adenocarcinoma is the most common cancer of the gastrointestinal tract in Korea, and its prognosis is related to several factors, such as depth of invasion, lymph node metastasis, and differentiation. Heat-shock proteins (HSPs) are present constitutively in normal cells, where they play an important role in normal cell metabolism. In mammarian cells, they are induced by a variety of physical and chemical stimuli. Among them, HSP70 is found at a higher level in growing cells than in resting cells. The p53 gene is located on the short arm of the chromosome 17 and acts as a cancer suppressor gene. A mutant p53 gene induces a malignant transformation. The mutant p53 protein binds with HSP70 and the p53-HSP70 complex has functional significance in the transforming capacity of the mutant p53. We evaluated the correlation between the HSP70 scores and the p53 protein expression by immunohistochemical methods and compared it with well-known prognostic factors, such as depth of invasion, size, histologic type, and DNA ploidy pattern, in 37 gastric adenocarcinomas. The HSP70 expression was scored according to the staining intensity and extent. An immunoreactivity of over 1% in tumor cell nuclei was considered as positive for p53 protein. The results are summarized as follows: The p53 protein expression rate did not significantly differ based on depth of invasion, histologic type, lymph node metastasis, or DNA ploidy. The HSP70 scores was higher in group II (AGC with TNM stage III) than in group I (EGC & AGC with TNM stage II) and in p53-positive carcinomas than in p53- negative carcinomas(P<0.05). In conclusion, the p53 protein and HSP70 were closely correlated to each other in our immunohistochemical study for gastric adenocarcinomas and the HSP70 scores may play a role in the progression of a gastric adenocarcinoma. However, further studies are needed for determining their prognostic values in gastric adenocarcinomas. HSP70 and p53 expression are factors, just like depth of invasion. The question is their value.