Loss of heterozygosity at the short arm of chromosome 3 occurs frequently in head and neck squamous cell carcinoma (HNSCC). FHIT, a candidate tumor suppressor gene, was recently identified at 3p14.2, and abnormalities of the gene were found in several types of human cancers. To investigate a potential role of the FHIT gene in HNSCC, we examined 16 HNSCC cell lines from 11 patients for abnormalities of the gene by using microsatellite analysis, reverse transcription-PCR, sequencing, and Southern blot analysis. We found that 13 of 16 (81%) cell lines exhibit loss of heterozygosity at 3p14.2. Seven cell lines from six individuals exhibited abnormal transcription patterns, including lack of a FHIT transcript in three lines and shortened transcripts in four lines. A further examination of coding sequences of FHIT in all lines with FHIT transcripts revealed a deletion of exon 4 in one line, a deletion of exons 5 to 7 in one line, and a deletion of exons 5 to 7 plus multiple small insertions between exons 4 and 8 in two lines derived from a primary tumor and a metastasis in the same individual. These results indicate that FHIT may have been inactivated in six cell lines from five (45%) individuals. We also observed two common polymorphism sites at codons 88 and 98 of the gene. These data indicate that abnormal transcription of the FHIT gene is common in HNSCC cell lines; however, other tumor suppressor gene(s) may reside at the same chromosomal region.
This study was supported in part by an M. D. Anderson Cancer Center PRS grant and National Cancer Institute Grant PO1 CA 52051. W. K. H. is a American Cancer Society Clinical Research Professor.