Fatty acid synthase expression in melanoma

Background: Fatty acid synthase (FAS), the key enzyme responsible for the synthesis of fatty acids, is weakly expressed in some normal human tissues. Recently, FAS has been demonstrated to be overexpressed in many non-neoplastic highly proliferative lesions and in aggressive carcinomas with poor outcome, including colon, breast and ovary carcinomas. Methods: In order to evaluate the prognostic significance of FAS in human melanoma, we analysed by means of immunohistochemistry, using a monoclonal anti-FAS antibody, 77 primary melanomas and 30 nodal and cutaneous metastasis. Thirty nevi (15 dermal and 15 junctional nevi) were used as controls. All patients were followed-up for 5 years. Results: Thirty-four melanomas expressed strong FAS immunostaining; the remaining 43 cases showed weak expression or were negative. All cutaneous and nodal metastasis were strongly positive. All patients with metastases deceased during the follow up period. Control specimens expressed weak staining. None of these patients developed recurrence. Statistical analysis revealed significant association of FAS expression with Breslow thickness (p=0.012). The intensity of FAS immunostaining was also predictive of prognosis (p=0.049). Conclusions: FAS is a reliable prognostic marker in human melanomas. FAS predictive strength is increased when associated with Breslow thickness. The observation of FAS in human melanomas may stratify patients for stricter follow-ups and suggest different therapeutic approaches.