A critical view of cell substrates with regard to cell transformation and cancer

The basic heuristic method in experimental medicine of proceeding from animals to human beings to facilitate the understanding of the etiology of a disease, is not completely relevant to viral oncogenesis in particular. The situation does not diminish scientific interest in tumor viruses because the study of these oncogens opens the way to identification of cancer genes and the understanding of their functions, expression and regulation in transformed cells. The results of these investigations are essential in comprehending animal tumor biology and from this, within limits, extrapolating to human neoplasia. However, the results of epidemiological, cellular and molecular approaches to human cancer all suggest a multiple and complex origin of this disease. In light of our current knowledge of cell transformation and cancer, the nature of permanent heteroploid cell lines is discussed in relation to their use as substrates for production of biologicals.