BACKGROUND: 7, 12-dimethylbenzanthracene (DMBA)-induced pancreatic intraepithelial neoplasia (PanIN) and pancreatic cancer in rats provide a classic model for uncovering the molecular mechanisms underlying pancreatic cancer. However, this model has not been characterized genetically, and in particular, the major genetic alterations in the p16 gene are unknown.
METHODS: Lesions of PanIN and pancreatic cancer were induced with DMBA implantation in 40 rats, and control pancreatic tissue was obtained from 10 age-matched rats without exposure to DMBA. Pancreatic tissue was harvested three months after DMBA implantation and DNA was extracted. Homozygous deletions and point mutations of the p16 (exons 1 and 2) gene were detected by PCR amplification and direct sequencing.
RESULTS: DMBA implantation in the 40 rats induced 26 PanINs and 9 carcinomas. The overall frequency of p16 alterations in the pancreatic tissue of these rats was 42.86% (15/35), and the changes were point mutations, not homozygous deletions. p16 mutations were present in 30.77% (8/26) of the rats with PanIN and 77.78% (7/9) of the rats with carcinoma (P<0.05). The increasing incidence of p16 alterations was detected in 20.00% (1/5) of PanIN-1, 28.57% (2/7) of PanIN-2 and 35.71% (5/14) of PanIN-3 lesions.
CONCLUSION: Our findings indicated that p16 alteration is a common event in the carcinogenesis of this model and that the mutation pattern is analogous to that of human lesions.