Fragile histidine triad gene and skin cancer.

Five years ago the fragile histidine triad (FHIT) gene including the most common fragile site locus of the human genome, FRA3B, was identified. The gene is altered in many types of cancer and several data support the idea that FHIT has to be considered a tumor suppressor. FHIT abnormalities were investigated in some skin tumors. Fifty-seven per cent of Merkel cell carcinomas displayed abnormal FHIT products but the involvement of FHIT in human non-melanoma skin cancer is still unclear. Because the murine Fhit locus is similar to its human homologue and is altered in cancer cell lines, we have established a strain of Fhit-deficient mice. After N-nitrosomethylbenzylamine treatment, the spectrum of tumors developed by the Fhit-deficient mice was similar to those observed in a familial skin cancer condition, the Muir-Torre syndrome, although there is no clear evidence yet for a relationship of FHIT and the human syndrome. Because cancer cells lacking in FHIT are defective in apoptosis, we propose the Fhit-deficient mouse as a model to understand a possible proapoptotic mechanism deficiency in the human syndrome.