This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Aquino, A. Articles by Glazer, R. I. Search for Related Content PubMed PubMed Citation Articles by Aquino, A. Articles by Glazer, R. I.

Role of Protein Kinase C in Phosphorylation of Vinculin in Adriamycin-resistant HL-60 Leukemia Cells

Laboratory of Biological Chemistry, Developmental Therapeutics Program, Division of Cancer Treatment, National Cancer Institute, Bethesda, Maryland 20892 [A. A., K. D. H., M. C. K., R. I. G.]; Division of Hematology/Oncology, Medical College of Virginia, Richmond, Virginia 23298 [S. G.]; and Section on metabolic Regulation, Endocrinology and Reproduction Research Branch, National Institute of Child Health and Human Development [K-P. H.] and Laboratory of Experimental Carcinogenesis, Division of Cancer Etiology, National Cancer Institute [C-H. N.], NIH, Bethesda, Maryland 20892

In response to phorbol esters such as 12-O-tetradecanoylphorbol-13-acetate (TPA), HL-60 cells differentiate to macrophage-like cells and exhibit the ability to phosphorylate vinculin in vitro. Adriamycin-resistant HL-60 (HL-60/ADR) cells similarly demonstrate this characteristic without prior treatment with TPA. Since protein kinase C (PK-C) is a cellular TPA receptor, we have examined the role of this enzyme in the inherent ability of HL-60/ADR cells to phosphorylate vinculin. DEAE-cellulose chromatography of cell extracts revealed that HL-60/ADR cells contained 2-fold more PK-C than did the parental cell line. All PK-C activity was found in the cytosol of wild type HL-60 cells, whereas 85% of PK-C activity was cytosolic and 15% was membrane-bound in HL-60/ADR cells. After a 2-day treatment with 10 nM TPA, PK-C activity was reduced 80–90% in both cell lines regardless of its intracellular distribution. Immunoblotting of cell extracts from HL-60/ADR cells or HL-60 cells following treatment with TPA revealed increased levels of a 52-kDa species of similar mass to M-kinase. Coincident with these changes after TPA treatment was a reduction in Ca²⁺ and phospholipid-independent phosphorylation of vinculin in vitro in extracts from HL-60/ADR cells, whereas HL-60 cells exhibited an elevation of this phosphoprotein. The phosphorylation of vinculin in TPA-treated HL-60 cells or untreated HL-60/ADR cells was blocked by antibodies to protein kinase C. These results suggest that it is not the absolute level of protein kinase C but rather the proteolytic activation of PK-C to a Ca²⁺ and phospholipid-independent form which is associated with the utilization of vinculin as an endogenous substrate.

¹ To whom requests for reprints should be addressed.

Received 8/ 3/87. Revised 2/29/88. Accepted 3/14/88.

This article has been cited by other articles:

				R. L. Fine, T. C. Chambers, and C. W. Sachs P-Glycoprotein, Multidrug Resistance and Protein Kinase C Oncologist, August 1, 1996; 1(4): 261 - 268. [Abstract] [Full Text] [PDF]

				R. Fine, T. Chambers, and C. Sachs P-glycoprotein, multidrug resistance and protein kinase C Stem Cells, January 1, 1996; 14(1): 47 - 55. [Abstract]