FHIT gene and the FRA3B region are not involved in the genetics of renal cell carcinomas.

The FHIT gene locus at 3p14.2 covers about 500 kb, including the fragile site FRA3B and the constitutional t(3;8) breakpoint associated with the development of multiple renal cell carcinomas (RCC). A terminal deletion of the short arm of chromosome 3 with the most distal breakpoint in the FRA3B region is the characteristic genetic event in nonpapillary RCC. Since aberrant FHIT transcripts have been observed in gastrointestinal and other tumors, this gene has been suggested to function as a tumor suppressor. To evaluate the role of FHIT and the FRA3B region in the genetics of RCC, we analyzed FHIT expression by RT-PCR and performed microsatellite deletion mapping in the FHIT region. In addition to two cases from a t(3;8) family, only three out of 100 sporadic nonpapillary RCC showed a breakpoint within the FHIT region, whereas 94 tumors showed a deletion breakpoint proximal to the FHIT gene. FHIT transcripts of normal size were observed in 33 out of 34 tumors. Direct sequencing of eight PCR products revealed a normal FHIT sequence without mutations in the coding region. An established cell line from a renal cancer xenograft showed a smaller FHIT transcript. Sequence analysis revealed a mixture of several splicing variants of the FHIT gene. Since only three out of 100 sporadic nonpapillary RCC had a deletion breakpoint within the FRA3B/FHIT region, and since all but one renal cell tumor showed a normal FHIT transcript, we can exclude the involvement of the FHIT gene and the FRA3B region in the genetics of renal cell cancer.