Apoptotic response to camptothecin and 7-hydroxystaurosporine (UCN-01) in the 8 human breast cancer cell lines of the NCI Anticancer Drug Screen: multifactorial relationships with topoisomerase I, protein kinase C, Bcl-2, p53, MDM-2 and caspase pathways

Int J Cancer. 1999 Jul 30;82(3):396-404. doi: 10.1002/(sici)1097-0215(19990730)82:3<396::aid-ijc13>3.0.co;2-z.


Derivatives of camptothecins, topoisomerase I inhibitors and 7-hydroxystaurosporine (UCN-01), a protein kinase C (PKC) inhibitor and cell cycle checkpoint abrogator, are promising anticancer drugs. We characterized the apoptotic response to camptothecin and UCN-01 for the 8 human breast carcinoma cell lines (MCF-7, MCF-7/ADR, T47D, HS578T, BT549, MDA-N, MDA MB231, MDA435) from the National Cancer Institute (NCI) Anticancer Drug Screen. MCF-7 and T47D cells exhibited marked resistance to apoptosis, whereas MCF-7/ADR (NCI/ADR-RES) and HS578T cells exhibited the most pronounced apoptotic response. Apoptotic response was not correlated with growth inhibition measured by sulforhodamine B (SRB) assay, indicating that apoptosis is not the only mechanism of drug-induced cell death. Measurements of topoisomerase I levels and cleavage complexes and of PKC isoforms demonstrated that primary target inhibition was not correlated with apoptotic response. Several key apoptotic pathways were evaluated. Only MCF-7 cells had wild-type p53, indicating that p53 is not required for drug-induced apoptosis. MCF-7 cells also showed the highest MDM-2 expression (along with T47D cells, which were also resistant to apoptosis). Bcl-2, Mcl-1 and caspases 2 and 3 protein levels varied widely, whereas Bax expression was comparable among cell lines. Interestingly, Bcl-2, Mcl-1 and Bcl-X(L) cumulative expressions were inversely correlated with apoptotic response. Our results provide a comparative molecular characterization for the breast cancer cell lines of the NCI Anticancer Drug Screen and demonstrate the diversity of cellular responses to drugs (apoptosis vs. cell cycle arrest) and the importance of multifactorial analyses for modulating/predicting the apoptotic response to chemotherapy.

MeSH terms

  • Alkaloids / administration & dosage
  • Antineoplastic Combined Chemotherapy Protocols / therapeutic use*
  • Apoptosis / drug effects*
  • Breast Neoplasms / drug therapy*
  • Breast Neoplasms / enzymology
  • Camptothecin / administration & dosage
  • Caspase Inhibitors
  • Drug Screening Assays, Antitumor
  • Enzyme Inhibitors / administration & dosage
  • Female
  • Humans
  • Neoplasm Proteins / biosynthesis
  • Nuclear Proteins*
  • Protein Kinase C / antagonists & inhibitors
  • Proto-Oncogene Proteins / biosynthesis
  • Proto-Oncogene Proteins c-bcl-2 / biosynthesis
  • Proto-Oncogene Proteins c-mdm2
  • Staurosporine / analogs & derivatives
  • Topoisomerase I Inhibitors
  • Tumor Cells, Cultured
  • Tumor Suppressor Protein p53 / biosynthesis


  • Alkaloids
  • Caspase Inhibitors
  • Enzyme Inhibitors
  • Neoplasm Proteins
  • Nuclear Proteins
  • Proto-Oncogene Proteins
  • Proto-Oncogene Proteins c-bcl-2
  • Topoisomerase I Inhibitors
  • Tumor Suppressor Protein p53
  • 7-hydroxystaurosporine
  • MDM2 protein, human
  • Proto-Oncogene Proteins c-mdm2
  • Protein Kinase C
  • Staurosporine
  • Camptothecin