Aberrant fragile histidine triad gene transcripts in primary hepatocellular carcinoma and liver cirrhosis

To determine whether transcriptional alterations of the fragile histidine triad (FHIT) gene play a role in the development and progression of human hepatocellular carcinoma (HCC) we used reverse transcription-PCR to examine mRNA FHIT expression in 28 paired samples of HCC (24 in cirrhotic and 4 in noncirrhotic livers) and matched noncancerous tissue and in 10 normal livers. We also assessed loss of heterozygosity of the polymorphic D3S1300 microsatellite marker in the intron between exons 5 and 6 of the FHIT gene. Abnormal FHIT transcripts were detected in 13 cases (46.4%): 10 in the cancerous tissue only, 1 with the same pattern in both cancerous and matched noncancerous tissue, and 2 in the noncancerous tissue only. The four HCCs that arose in noncirrhotic liver all showed abnormal FHIT transcripts. No alterations were found in normal livers. Sequence analysis of abnormally sized transcripts revealed that they were generated by the fusion of exons 3 or 4 with exons 8 or 9. Among the cancerous specimens, one case showed only an abnormal sized transcript derived from the fusion of exons 4 and 9 in the absence of any normal-sized transcript, and another case showed deletion of a sequence comprised between nucleotides -35 and 399 resulting in an exon 4-9 fusion not respecting the exons' bounds. Loss of heterozygosity was found in two cases with abnormal FHIT transcripts and in only one case with normal transcript. Patients with aberrant FHIT transcripts showed a significantly higher relapse rate and shorter recurrence time (P = 0.001). This could be related to a primary genomic instability affecting particularly susceptible regions like FRA3B and could be associated with an increasing risk of recurrence without involving a causative role.