Nontumoral, benign ad malignant stages of transformation of a diploid pig cell line. A review.

The PFT cell line originated from diploid endometrial cells and was subcultured more than 500 times. Nontumoral, benign and malignant transformation appeared at different stages. Four populations (F1, F2, F3 and F4) of cells were demonstrated sequentially by chromosomes analysis. These consisted of eight phenotypes corresponding to the sequential appearance of markers which included three chromosomal aberrations. The PFT malignant transformation in vitro is a progressive process through qualitatively different stages and may reflect neoplastic development in vivo. It is suggested that the benign and malignant transformations were under separate genetic control since they occurred after two chromosomal translocations on two different chromosomes. The spontaneous expression of a pig endogenous type-C virus which occurred concomitantly with the first translocation appeared to be related to oncogenesis.