Distribution of phorbol ester TPA-induced structural chromosomal aberrations in HeLa cells.

In order to gain further insight into the mechanism of clastogenic action of the phorbol ester 12-O-tetradecanoyl-phorbol-13-acetate (TPA), the localization and distribution of structural chromosomal aberrations on HeLa chromosomes was investigated. We have shown by the G-banding technique that TPA-induced chromosomal aberrations in HeLa cells have practically the same distribution as that occurring spontaneously in control cultures. About two-thirds of the breakpoints are located in areas of known fragile sites; about one-third is located in regions near known oncogenes. The tumor promoter TPA thus appears to enhance pre-existing mechanisms of an 'endogeneous' clastogenesis.