Lethality and transformation of 10T1/2 mouse embryo fibroblast cell line by various wavelengths of ultraviolet radiation.

The wavelength dependence for cell killing and induction of oncogenic transformation in 10T1/2 cells, a C3H mouse embryo fibroblast cell line, was investigated. Ultraviolet radiation (UV) in the UVA (315-400 nm), UVB (280-340 nm), and UVC (254 nm) regions of the electromagnetic spectrum caused cell death and induced neoplastic transformation of 10T1/2 cells. Lethality and transformation induced by 3 different types of light source encompassing 4 ranges of wavelength were compared, using several parameters. The total energy required to reduce cell survival and to induce a given transformation frequency (e.g., 10(-3) transformants/surviving cell) increased with longer wavelengths, indicating that longer wavelengths are less cytotoxic and carcinogenic than the same dose of radiation at shorter wavelengths. However, when the frequency of transformation was calculated per lethal event (delta T values), all the wavelength ranges tested were found to be similarly effective in inducing transformation. This suggests that the lesions in DNA responsible for oncogenic transformation and lethality are the same for all the wavelength ranges tested. Although wavelengths above 300 nm are inefficient in their ability to induce transformation, their abundance in sunlight may make them a significant factor in carcinogenesis.