The fragile histidine triad (FHIT) gene is a tumor-associated gene, and aberrant FHIT gene and protein expression have been described in many types of human tumor's. Furthermore, it has been reported that FHIT gene inactivation is induced by hypermethylation of 5' CpG islands in the gene or by genomic deletion around the open reading frame (ORF). In this study, we explored the aberrations in the canine FHIT gene and Fhit protein expression and assessed the methylation status and genomic deletions by using 5 canine lymphoma cell lines. We found that the decrease in the expression of the Fhit protein in canine lymphoma cell lines was similar to that in human tumors. The expression of the wild-type FHIT transcript was reduced in all 5 cell lines. However, we could not confirm the involvement of aberrant methylation events in the 5' CpG islands of the canine FHIT gene. We were able to identify homozygous or heterozygous deletions in the canine FHIT genes in all 5 cell lines. Moreover, a widespread genomic deletion of the FHIT gene, which included the ORF region, was detected in I cell line. In the present study, we detected aberrations in the FHIT gene and Fhit protein expression in all 5 canine lymphoma cell lines, and this phenomenon might be,in important factor in promoting canine lymphoma.
