Flavopiridol inversely affects p21WAF1/CIP1and p53 and protects p21-sensitive cells from paclitaxel

Mikhail V. Blagosklonny*, Zbigniew Darzynkiewicz, William D. Figg

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

27 Scopus citations


Resting cells are relatively resistant to microtubule-active drugs including paclitaxel (PTX). By causing p53-mediated arrest, pretreatment with low concentrations of doxorubicin (DOX) protected HCT116 cells from the cytotoxicity caused by PTX. Unlike DOX, flavopiridol (FL) did not protect HCT116 cells. Low concentrations of FL (50 nM) induced p21 but not p53. High concentrations of FL (500 nM) decreased levels of p21 and Mdm-2 but dramatically induced p53. Thus, FL reciprocally affects p21 and p53. In LNCaP, a prostate cancer cell line which is highly sensitive to p21-induced growth arrest (p21-sensitive), low concentrations of FL (50 nM) induced p21 (without induction of p53) and caused G1 and G2 arrest. This precluded mitotic arrest, Bcl-2 and Raf-1 phosphorylation, and diminished cell death caused by PTX. In contrast, FL did not protect PC3M, arrest-resitant and highly aggressive prostate cancer cells. Like LNCaP, HL60 and SKBr3 cells are known to be p21-sensitive. As predicted, low concentrations of FL antagonized PTX-mediated cytotoxicity in HL60 and SKBr3 cell lines. In summary, only low concentrations of FL can induce p21, and, in turn, only p21-sensitive cells are protected from PTX.

Original languageEnglish
Pages (from-to)420-425
Number of pages6
JournalCancer Biology and Therapy
Issue number4
StatePublished - Jul 2002
Externally publishedYes


  • Flavopiridol
  • Paclitaxel
  • p21
  • p53


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