Bryostatin 1 activates protein kinase C and induces monocytic differentiation of HL-60 cells

R. M. Stone, E. Sariban, G. R. Pettit, D. W. Kufe

Research output: Contribution to journalArticlepeer-review

124 Scopus citations


Phorbol esters induced the human HL-60 promyelocytic cell line to differentiate along a monocytic pathway. This induction of differentiation may involve phorbol ester-induced activation of the phospholipid- and calcium-dependent protein kinase C. Bryostatin 1, a macrocyclic lactone, has been shown to compete with phorbol esters for binding to protein kinase C. We have confirmed that bryostatin 1 translocates activity of protein kinase C from the cytosolic to membrane fractions of HL-60 cells. The present results also demonstrate that bryostatin 1 (10 nmol/L) induces monocytic differentiation of HL-60 cells as determined by adherence, growth inhibition, appearance of monocyte cell surface antigens, and α-naphthyl acetate esterase staining. Furthermore, bryostatin 1 (10 nmol/L) downregulated c-myc expression and induced c-fos, c-fms, and tumor necrosis factor transcripts. These changes in gene expression induced by bryostatin 1 are similar to those associated with phorbol ester-induced monocytic differentiation of HL-60 cells. In contrast, exposure to a higher concentration of bryostatin 1 (100 nmol/L) had less of an effect on growth inhibition of HL-60 cells and changes in gene expression. Moreover, 100 nmol/L bryostatin 1 antagonized the cytostatic effects and adherence induced by phorbol esters. Our results thus suggest that bryostatin 1 activates HL-60 cell protein kinase C and that this effect is associated with induction of monocytic differentiation.

Original languageEnglish (US)
Pages (from-to)208-213
Number of pages6
Issue number1
StatePublished - 1988

ASJC Scopus subject areas

  • Biochemistry
  • Immunology
  • Hematology
  • Cell Biology


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