Comparison of the colony forming ability and invasive potential of six primate cell lines treated with retinoic acid.

Four human and two nonhuman primate cell lines were studied to determine their growth characteristics in soft agar, and for invasive characteristics in a muscle organ culture assay system. The cell lines ranged from normal human diploid to frankly tumorigenic in animal models. Additional studies were performed to assess the effects of retinoic acid (RA) on colony forming ability and invasion. The results showed a wide range of cloning efficiencies among the cell lines tested, as well as the degree of invasiveness. Of the soft agar growth parameters studied, colony growth index correlated best with invasion in the organ culture assay. RA significantly inhibited the growth of the tumor cells in soft agar, but failed to inhibit invasion in the organ culture assay although there was inhibition of surface proliferation. The data are consistent with the suggestion that cell proliferation and invasion are not necessarily linked characteristics.