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

Abstract

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 (CdCl 2) can induce morphological cell transformation, DNA from CdCl 2-induced transformed cells can transform other mammalian cells, and the transformed cells induced by CdCl 2 can form tumors in nude mice. BALB/c-3T3 cells were treated with different concentrations of CdCl 2 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 CdCl 2-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 CdCl 2 were injected into both axillary regions of nude mice. Mice were screened once a week for the appearance and size of tumors. CdCl 2 caused a statistically significant, concentration-related increase in the transformation frequency. DNA from all five CdCl 2-induced transformed cell lines tested was found to induce varying degrees of transfection-mediated transformation in NIH-3T3 cells. All 10 CdCl 2-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 CdCl 2 is capable of inducing morphological cell transformation and that the transformed cells induced by CdCl 2 are potentially tumorigenic.