Betel quid chewing is a general oral habit in Taiwan, India, southeastern Asian and South Africa with or without the additive of tobacco, alcohol or lime. In this study, the tumor-promoting neoplastic transformation effect of Lime-Piper betel quid (LPB) was examined on JB6 cells. The treatment of LPB at a high dose (1.0 mg/ml) for over 5 days or at lower doses (0.1, 0.5 mg/ml) for over 15 days induced the formation of transformed foci. The transformed cells showed the characteristics of colony formation in soft agar, higher growth rate and multilayer on culture dish. A two-fold induction of the protein levels of c-fos and c-jun proto-oncogenes was observed in the cells from the 50th passage (Cl1/p50, Cl2/p50 and Cl3/p50), suggesting that LPB-transformed cells were oncogenic. In addition, the LPB-transformed cells possessed an elevated level of c-Myc and an increased cell population distributed in the S phase of the cell cycle. These results demonstrated the promotion effect of LPB and indicate that it could be a tumor promoter.
