OBJECTIVETo explore the expression and sequence of ERCC1 gene in CdCl2-induced transformed human bronchial epithelial 16HBE cells at different stages.

METHODSReverse transcription-polymerase chain reaction (RT-PCR) and immunohistochemcial staining (SP method) were used to measure the ERCC1 mRNA and protein expression in 16HBE cells at different passages treated with CdCl2 (the 5th, 15th, 35th passage, and neoplastic cells from tumors formed in nude mice). ERCC1 exon 3,exon 4 of the 16HBE cells and tumor cells from nude mice were amplified by polymerase chain reactions (PCR), the amplified DNA strips were purified,and the exons were detected by DNA analysis.

RESULTSDuring the passages of 16HBE cells treated with CdCl2, the expression of ERCC1 gene was decreased gradually. The ERCC1 gene mRNA and protein expression levels of the CdCl2-transformed 35th passage 16HBE cells and tumor cells from nude mice were significantly decreased comparing with those in non-transformed 16HBE cells (P < 0.01). In the CdCl2-induced tumorigenic cells in nude mice, there was adenine (A) deletion in 1st site of ERCC1 exon 4. The mutation was frame shift mutation.

CONCLUSIONThe decreased expression and mutation of ERCC1 gene may be the possible carcinogenic mechanism of CdCl2.