Fhit gene alterations in hepatocarcinogenesis induced by a choline-deficient L-amino acid-defined diet in rats.

Abstract

Alterations of the fragile histidine triad (Fhit) gene were investigated in rat hepatocarcinogenesis induced by a choline-deficient L-amino acid-defined (CDAA) diet. Males of the F344 strain, 6 wk of age, were fed a CDAA diet, and subgroups were killed at 2, 4, 12, 20, and 75 wk after the beginning of the experiment. Fifteen hepatocellular carcinomas (HCCs) were noted in rats by the last time point; they were dissected free from the surrounding tissue. Normal control liver specimens were obtained from 6-wk-old rats. Total RNAs were extracted from whole livers of animals fed the CDAA diet for 2, 4, 12, and 20 wk and from HCCs, for assessment of aberrant transcription of the Fhit gene by reverse transcription-polymerase chain reaction. Aberrant transcripts were detected in livers of rats fed the CDAA diet for 4, 12, and 20 wk, but not 2 wk, as well as in 11 of 15 HCCs (73.3%). Southern blot analysis showed a genomic DNA abnormality in one of seven informative HCCs (14.3%), while Western blot analysis showed reduction of Fhit protein expression in seven of nine HCCs (77.8%). No abnormal expression was evident in the livers after exposure to the CDAA diet for 2-20 wk. These results suggest that Fhit alterations may play important roles in hepatocarcinogenesis due to choline deficiency in rats.