UCN-01 selectively enhances mitomycin C cytotoxicity in p53 defective cells which is mediated through S and/or G(2) checkpoint abrogation.
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.
Sugiyama
K
K
Pharmaceutical Research Institute, Kyowa Hakko Kogyo Co., Ltd., Shizuoka, Japan.
Shimizu
M
M
Akiyama
T
T
Tamaoki
T
T
Yamaguchi
K
K
Takahashi
R
R
Eastman
A
A
Akinaga
S
S
D000470:Alkaloids / Q000633:toxicity*; D000970:Antineoplastic Agents / Q000633:toxicity*; D001943:Breast Neoplasms; D002294:Carcinoma, Squamous Cell; D002453:Cell Cycle / Q000187:drug effects*; D002470:Cell Survival / Q000187:drug effects*; D019926:Cyclin B / Q000378:metabolism; D056744:Cyclin B1; D050759:Cyclin-Dependent Kinase Inhibitor p21; D018844:Cyclin-Dependent Kinases / Q000037:antagonists & inhibitors; D016213:Cyclins / Q000378:metabolism; D004249:DNA Damage; D004357:Drug Synergism; D005260:Female; D016195:G2 Phase; D016158:Genes, p53; D006801:Humans; D020287:In Situ Nick-End Labeling; D016685:Mitomycin / Q000633:toxicity*; D011494:Protein Kinases / Q000378:metabolism; D016196:S Phase; D019311:Staurosporine / Q000031:analogs & derivatives; D014407:Tumor Cells, Cultured
D000470:Alkaloids; D000970:Antineoplastic Agents; C534699:CCNB1 protein, human; C493956:CDKN1A protein, human; D019926:Cyclin B; D056744:Cyclin B1; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D016685:Mitomycin; C054852:7-hydroxystaurosporine; D011494:Protein Kinases; C102333:histone H1 kinase; D018844:Cyclin-Dependent Kinases; D019311:Staurosporine