Transforming and carcinogenic potential of cadmium chloride in BALB/c-3T3 cells

A large number of workers are potentially exposed to cadmium during mining and processing. Therefore, there is a concern regarding the potential carcinogenic hazards of cadmium to exposed workers. Studies have been performed to determine if cadmium chloride (CdCl2) can induce morphological cell transformation, DNA from CdCl2-induced transformed cells can transform other mammalian cells, and the transformed cells induced by CdCl2 can form tumors in nude mice. BALB/c-3T3 cells were treated with different concentrations of CdCl2 for 72 h. The frequency of transformed foci from each treatment was determined after cells were cultured for 4 to 5 weeks. DNAs from five CdCl2-induced transformed cell Lines were isolated and gene transfection assay was performed using NIH-3T3 cells. Non-transformed BALB/c-3T3 cells and cells from 10 transformed cell lines induced by CdCl2 were injected into both axillary regions of nude mice. Mice were screened once a week for the appearance and size of tumors. CdCl2 caused a statistically significant, concentration-related increase in the transformation frequency. DNA from all five CdCl2-induced transformed cell lines tested was found to induce varying degrees of transfection-mediated transformation in NIH-3T3 cells. All 10 CdCl2-induced transformed cell lines formed fibrosarcomas in nude mice within 39 days of inoculation. Within this time period, no tumors were found in nude mice injected with non-transformed BALB/c-3T3 cells. These results indicate that CdCl2 is capable of inducing morphological cell transformation and that the transformed cells induced by CdCl2 are potentially tumorigenic. (C) 2000 Elsevier Science B.V. All rights reserved.