PLEOMORPHIC ADENOMA CELLS VARY IN THEIR SUSCEPTIBILITY TO SV40 TRANSFORMATION DEPENDING ON THE INITIAL KARYOTYPE

Chromosomal aberrations involving 8q 12 or 12q 13-15 characterize two cytogenetic subgroups of salivary gland pleomorphic adenomas. As the tumors of the two groups differ in their clinical and histologic characteristics, we decided to determine their susceptibility to SV40 transformation. We transfected cell cultures from 13 adenomas with aberrations involving 8q 12 and from seven adenomas with involvement of 12q 13-15 using an SV40 plasmid coding for the early region of the viral genome. Whereas all cultures with aberrations of 12q 13-15 showed transformed foci, only 4 of the 13 cultures with 8q 12 abnormalities showed foci of transformed cells. We also observed a much higher immortalization rate in the first group (3/7 vs. 1/ 13). All successfully transformed tumor cell cultures showed a relatively stable karyotype in the pre-crisis stage and a high mitotic index, were T-antigen positive, and had an extended life span in vitro.