OBJECTIVETo transform HPV E6/E7 immortalized human oral epithelial cell (HIOEC) line cells by benzo(a)pyrene [B(a)P] in vitro, and to establish a carcinogenesis model of oral squamous cell carcinoma.

METHODSHIOEC cells were treated with 0.1 mg/L-1.2 mg/L B(a)P for 6 months. The cells were cloned at 18th passage, and then the culture medium was changed into DMEM containing 10% FBS at 21th passage. Cells were cultured in vitro for half and one year and the cell line was named HIOEC-B(a)P. The morphological changes of the cells were observed with differential interference contrast microscope and HE staining. The soft agar colony forming ability and tumorigenicity of the cells in nude mice were identified to confirm the malignant characteristics of HIOEC-B(a)P cells.

RESULTS(1) After HIOEC cells were treated with B(a)P for 6 months, HIOEC-B(a)P cells could grow well in DMEM medium containing 10% FBS and physical concentration of calcium. (2) When HIOEC cells were treated with chemical carcinogens, the morphology of the cells was changed. Cells showed the character of polygon epithelial cells with much atypical mitosis. (3) The 93th passage of HIOEC-B(a)P cells had soft agar colony formation ability. (4) The 55th passage of HIOEC-B(a)P cells could develop parakeratosis mass. The 69th passage of HIOEC-B(a)P cells could develop typical well-differentiated squamous cell carcinoma. The 74th and the 96th HIOEC-B(a)P cells developed I-II grade squamous cell carcinoma-like clinical lesions in nude mice.

CONCLUSIONSB(a)P may induce HIOEC cells to be oral squamous cell carcinoma (OSCC) carcinogenetic cells. It will provide a multiple factors, multistage carcinogenesis model of OSCC for the further research.