Analysis of Fas Gene Mutations on Laser Capture Microdissected Specimens from Renal Cell Carcinoma

Renal cell carcinoma (RCC) expresses Fas antigen on the cell surface, and thus could be sensitive to apoptosis induced by the binding of Fas ligand. Fas gene mutations might be involved in the development of RCC. Fas gene mutations were examined in genomic DNA extracted from RCC lesions. With use of laser capture methods, one RCC and one non‐neoplastic lesion per case were microdissected from 15 patients with RCC. Polymerase chain reaction‐amplified products were directly sequenced. Loss of heterozygosity (LOH) was examined at four sites of known polymorphism. Mutations of the Fas gene were detected in 3 RCC lesions from 3 (20%) of 15 cases. All mutations were point mutations, 2 missense and one silent, in exons 7 and 9. Non‐neoplastic tissues never showed Fas gene mutations. Nine of 15 cases (60.0%) were heterozygous for one or more sites of the known biallelic polymorphisms, i.e., at nucleotides ‐1377, ‐670, 416, and 836. Two of these 9 cases showed LOH at promoter region ‐670. Mouse T‐cell lymphoma cells transfected with missense mutated genes were resistant to apoptosis induced by anti‐Fas antibody, indicating these to be loss‐of‐function mutations. The results of the present study suggest that Fas gene mutations play a role in the pathogenesis of RCC.