The data presented in this paper show that endogenous Hsp70 protects cancer cells of different origins from a variety of cytotoxic threats including cancer cell therapeutics. In contrast, however, Hsp70 released from stressed cancer cells can serve as a danger signal or may recruit cells responsible for the generation of innate and adaptive immune responses against tumour cells.

The recent advances in designing Hsp70-based anti-cancer vaccines and the ability of the chaperone to penetrate inside a living cell prompted us to develop a non-invasive method for the treatment of surface tumors. We designed hydrogel-containing gel-forming substances and human recombinant Hsp70 and applied them on the surface of a 7-day-old B16F10 melanoma tumor. According to the results of histochemistry, Hsp70 diffused through skin layer inside the B16 tumor, and this transport was proved by biochemical data. The application of Hsp70 gel reduced the rate of tumor growth by 64 % and prolonged the life of animals by 46 %. Increased survival was correlated with the enhancement of B16-specific cytotoxicity and up-regulation of gamma-interferon production. Taken together, the data confirm the anti-tumor effect of pure recombinant Hsp70 delivered intratumorally and demonstrate the relevance of a novel non-invasive technology of Hsp70-based therapy.