Pharmacodynamics of cytarabine alone and in combination with 7-hydroxystaurosporine (UCN-01) in AML blasts in vitro and during a clinical trial

Deepa Sampath, Jorge Cortes, Zeev Estrov, Min Du, Zheng Shi, Michael Andreeff, Varsha Gandhi, William Plunkett

Research output: Contribution to journalArticle

92 Scopus citations


Chk1 and Akt signaling facilitate survival of cells treated with nucleoside analogues. Activation of Chk1 in response to cytarabine (ara-C) induced an S-phase checkpoint characterized by the inhibition of Cdk2, cell cycle arrest, no change in constitutively active Akt, or low-stress kinase signaling in ML-1 cells. However, inhibition of Chk1 by UCN-01 in S-phase-arrested cells resulted in an abrogation of the checkpoint, inhibition of Akt, activation of JNK, and a rapid induction of myelogenous leukemia (AML) blasts exposed to ara-C and UCN-01 demonstrated a selective loss in cloning potential when compared with normal progenitors. Therefore, we evaluated a pilot clinical trial of ara-C in combination with UCN-01 in patients with relapsed AML. Blasts from some patients demonstrated a previously activated Chk1-Cdk2 DNA damage response pathway that decreased during therapy. Constitutively phosphorylated Akt kinase declined on addition of UCN-01 to the ara-C infusion, an action accompanied by an activation of JNK and reduction in absolute AML blast counts. Thus, use of UCN-01 in combination with ara-C decreases Chk1 phosphorylation, inhibits the Akt survival pathway, and activates JNK during the course of therapy, offering a rationale for the cytotoxic action of this combination during AML treatment.

Original languageEnglish (US)
Pages (from-to)2517-2524
Number of pages8
Issue number6
StatePublished - Mar 15 2006
Externally publishedYes


ASJC Scopus subject areas

  • Biochemistry
  • Immunology
  • Hematology
  • Cell Biology

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