Induction of human promyelocytic leukemia HL-60 cell differentiation into monocytes by silibinin: Involvement of protein kinase C

So N. Kang, Mi H. Lee, Kyeong Man Kim, Dae Ho Cho, Tae Sung Kim

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The effect of silibinin, an active component of Silybum marianum, on cellular differentiation was investigated in the human promyelocytic leukemia HL-60 cell culture system. Treatment of HL-60 cells with silibinin inhibited cellular proliferation and induced cellular differentiation in a dose-dependent manner. Cytofluorometric analysis and morphologic studies indicated that silibinin induced differentiation of HL-60 cells predominantly into monocytes. Importantly, strongly synergistic induction of differentiation into monocytes was observed when silibinin was combined with 5 nM 1α,25-dihydroxyvitamin D3 [1,25-(OH)2D3], a well-known differentiation inducer of HL-60 cells into the monocytic lineage. Silibinin enhanced protein kinase C (PKC) activity and increased protein levels of both PKCα and PKCβ in 1,25-(OH)2D3-treated HL-60 cells. PKC and extracellular signal-regulated kinase (ERK) inhibitors significantly inhibited HL-60 cell differentiation induced by silibinin alone or in combination with 1,25-(OH)2D3, indicating that PKC and ERK may be involved in silibinin-induced HL-60 cell differentiation.

Original languageEnglish
Pages (from-to)1487-1495
Number of pages9
JournalBiochemical Pharmacology
Issue number12
Publication statusPublished - 2001 Jun 15
Externally publishedYes



  • 1α,25-Dihydroxyvitamin D
  • Extracellular signal-regulated kinase
  • HL-60 cell differentiation
  • Protein kinase C
  • Silibinin

ASJC Scopus subject areas

  • Pharmacology

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