Tumor-promoting phorbol diester-induced specific changes in cell surface glycoprotein profile of K562 human leukemic...

The tumor-promoting phorbol ester, 12-O-tetradecanoylphorbol-13-acetate (TPA), induced specific changes in the cell surface glycoprotein profile of K562 human leukemic cells. TPA-treated K562 cells were examined by cell surface labeling followed by immunoprecipitation with anti-glycophorin antiserum or anti-K562 antiserum. TPA-treated K562 cells lost glycophorin and glycoprotein with a molecular weight of 105,000, which are specific to later stages of erythroid cell differentiation, and retained glycoprotein with a molecular weight of 95,000, which is specific to early stages of erythroid cell differentiation. On the other hand, 4 alpha-phorbol-12,13-didecanoate, which is inactive as a tumor promoter, induced no significant changes in cell surface glycoproteins of K562 cells. In parallel, TPA induced morphological changes of K562 cells as their growth was inhibited, whereas 4 alpha-phorbol-12,13-didecanoate had no effect on these two characteristics. Thus, the tumor promoter induced specific changes in the cell surface glycoprotein profile of K562 human leukemic cells, which appeared to be induced into a retrodifferentiated stage.