UCN-01 selectively enhances mitomycin C cytotoxicity in p53 defective cells which is mediated through S and/or G(2) checkpoint abrogation

Int J Cancer. 2000 Mar 1;85(5):703-9. doi: 10.1002/(sici)1097-0215(20000301)85:5<703::aid-ijc17>3.0.co;2-7.


We have previously reported that UCN-01 (7-hydroxystaurosporine), a protein kinase inhibitor that is under clinical trials as an anti-cancer agent in the USA and Japan, enhanced the anti-tumor activity of mitomycin C (MMC) in vitro and in vivo. Subsequent studies from other laboratories revealed that UCN-01 could selectively enhance cytotoxicity of DNA damaging agents in p53 defective cells and that this was mediated by abrogation of S and /or G(2) arrest by UCN-01. In this study, we report that UCN-01 selectively enhances the cytotoxicity of MMC in human p53 mutant cell lines. In contrast, UCN-01 showed little, if any, effect on MMC cytotoxicity in human p53 wild-type cell lines. Terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-nick end-labeling (TUNEL) assay revealed that the combination of MMC with UCN-01 increased DNA breaks consistent with apoptosis in p53 defective A431 epidermoid carcinoma cells. In p53 wild-type MCF-7 breast carcinoma cells, the cyclin-dependent kinase inhibitor protein p21/WAF1 was markedly induced after the treatment with MMC alone, although this response was significantly delayed from the time of MMC treatment. Detailed cell-cycle studies revealed that UCN-01 abrogated S and G(2) phase accumulation induced by MMC in p53 defective cells and to a lesser extent in p53 wild-type cell lines. The abrogation of arrest in p53 wild-type cells was observed prior to significant induction of the p53 response. Since MMC was less effective against p53 defective cell lines than against p53 wild-type cell lines and UCN-01 selectively enhanced MMC cytotoxicity in p53 defective cell lines, UCN-01 may provide a new modality of MMC-based cancer chemotherapy, particularly in p53 defective cancer patients.

MeSH terms

  • Alkaloids / toxicity*
  • Antineoplastic Agents / toxicity*
  • Breast Neoplasms
  • Carcinoma, Squamous Cell
  • Cell Cycle / drug effects*
  • Cell Survival / drug effects*
  • Cyclin B / metabolism
  • Cyclin B1
  • Cyclin-Dependent Kinase Inhibitor p21
  • Cyclin-Dependent Kinases / antagonists & inhibitors
  • Cyclins / metabolism
  • DNA Damage
  • Drug Synergism
  • Female
  • G2 Phase
  • Genes, p53*
  • Humans
  • In Situ Nick-End Labeling
  • Mitomycin / toxicity*
  • Protein Kinases / metabolism
  • S Phase
  • Staurosporine / analogs & derivatives
  • Tumor Cells, Cultured


  • Alkaloids
  • Antineoplastic Agents
  • CCNB1 protein, human
  • CDKN1A protein, human
  • Cyclin B
  • Cyclin B1
  • Cyclin-Dependent Kinase Inhibitor p21
  • Cyclins
  • Mitomycin
  • 7-hydroxystaurosporine
  • Protein Kinases
  • histone H1 kinase
  • Cyclin-Dependent Kinases
  • Staurosporine