PROTEIN-KINASE-C ACTIVITY IN HUMAN LEUKEMIA-CELL LINES WITH REFERENCETO SENSITIVITY TO ANTINEOPLASTIC AGENTS

Protein kinase C (PKC) regulates many cellular processes. In view of i ts possible relevance to the drug resistance, the levels of PKC activi ty were assessed in human leukemia cell lines with reference to the se nsitivity to antineoplastic agents. K562/ADM exhibited approximately 2 -fold higher levels of PKC activity as compared with the parental K562 . After a 1-hr preincubation with Adriamycin (ADM) (0.5, 1, 10 muM), P KC activity in K562 tended to increase dose-dependently, while no subs tantial alteration was found in K562/ADM. Cisplatin (CDDP) or etoposid e was of no effect. The activity in THP-1/E was slightly lower than TH P-1, and the basal level stayed unchanged with any one of the above du rgs. These results suggest that in K562 increase in PKC activity with ADM may play a role in the process of acquisition of resistance.