Membrane expression of heat shock protein 70 (Hsp70) on head and neck cancer

Abstract

Problem: Besides its intracellular chaperoning function, the major stress-inducible heat shock protein 70 (Hsp70) has been found to play key roles in cancer immunity. Hsp70 was detected on a variety of human tumor cell lines, but not on normal cells. The aim of the study was to determine the membrane expression of Hsp70 and MHC class I on freshly isolated biopsy material derived from head and neck cancer patients. Methods: A single cell suspension was prepared from the fresh biopsy material. Viable cells were used for flow cytometric analysis using the Hsp70 antibody clone cmHsp70.1, the MHC I antibody W6/32 and isotype-matched control antibodies. Results: An MHC class I expression was found in 57 of 59 (97%) tumor biopsy materials. Forty-three of 57 were found to be Hsp70 membrane-positive (75%); tongue and mouth 13 of 16 (81%); oropharynx 20 of 26 (77%); and larynx 10 of 15 (67%). The corresponding control tissues were negative for membrane-bound Hsp70. Conclusion: Similar to tumor cell lines, head and neck tumor biopsies, express Hsp70 on their cell surface, but normal tissues do not. Significance: A tumor-selective Hsp70 membrane localization has been found to provide a target recognition structure for human natural killer (NK) cells in vitro. Therefore one might speculate about the immunotherapeutical potential of membrane-bound Hsp70 on head and neck cancer. Support: None reported.