p53-HSP70 complexes in oral dysplasia and cancer: potential prognostic implications.

We have previously shown overexpression of p53 and 70 kDa heat shock protein (HSP70) in potentially malignant, as well as malignant, oral lesions in an Indian population, suggesting that alterations of p53 and HSP70 expression may occur in the early stages of oral tumorigenesis. Herein we report immunological evidence for the specific association between p53 and HSP70 in potentially malignant and malignant oral lesions. This association was indicated by coimmunoprecipitation of p53 and HSP72/73 proteins observed with either an anti-p53 monoclonal antibody or an anti-HSP72/73 antibody. Furthermore, reciprocal blotting analysis showed that HSP72/73 proteins did not share an epitope with p53, confirming that the coimmunoprecipitation of p53 and HSP72/73 is a physical association of the proteins in potentially malignant lesions (dysplasia) and oral squamous cell carcinomas (SCCs). p53-HSP70 complex formation was observed in 19/52 cases of oral SCCs and 10/53 cases of potentially malignant lesions (leucoplakia). Normal oral mucosa did not show the presence of p53-HSP70 complexes (0/20 cases). p53-HSP70 complex formation may be one of the mechanisms of stabilisation of p53 protein resulting in its increased levels in potentially malignant and malignant oral lesions and may be implicated in oral carcinogenesis.