OBJECTIVETo detect the alteration of fragile histidine triad (FHIT) gene and p16 gene during malignant transformation of immortal human bronchial epithelial cell line (16HBE) induced by crystalline nickel sulfide, and study the molecular mechanism of nickel carcinogenesis.

METHODSMalignant transformed cells and tumorigenic cells were examined for the alteration of FHIT gene and p16 gene by RT-PCR, DNA sequencing and silver staining PCR-SSCP.

RESULTSCompared with those of control 16HBE, neither mutation of exon2 or exon2-3, abnormal expression in p16 gene nor mutation of FHIT exon5, 6, 7 and 8, exon1-4 or exon5-9 were observed in transformed cells and tumorigenic cells. But aberrant transcript or FHIT gene expression loss were observed in transformed cells and tumorigenic cells. One of the aberrant transcripts in FHIT gene, the deletion of exon6, exon7 and exon8 and an insertion of 36 bp sequence replacing exon6-8, was confirmed by sequencing.

CONCLUSIONFHIT gene, not p16 gene, could play a definite role in nickel carcinogenesis. Alterations of FHIT gene induced by crystalline NiS could be a molecular event associated with carcinogen, chromosome fragile site instability and cell malignant transformation, and FHIT gene could be one of the important target genes activated by exotic carcinogens.