Enhanced sensitivity to irinotecan by Cdk1 inhibition in the p53-deficient HT29 human colon cancer cell line.
Mutations in the tumor-suppressor gene p53 have been associated with advanced colorectal cancer (CRC). Irinotecan (CPT-11), a DNA topoisomerase 1 inhibitor, has been recently incorporated to the adjuvant therapy. Since the DNA-damage checkpoint depends on p53 activation, the status of p53 might critically influence the response to CPT-11. We analysed the sensitivity to CPT-11 in the human colon cancer cell line HT29 (mut p53) and its wild-type (wt)-p53 stably transfected subclone HT29-A4. Cell-cycle analysis in synchronised cells demonstrated the activation of transfected wt-p53 and a p21(WAF1/CIP1)-dependent cell-cycle blockage in the S phase. Activated wt-p53 increased apoptosis and enhanced sensitivity to CPT-11. In p53-deficient cells, cDNA-macroarray analysis and western blotting showed an accumulation of the cyclin-dependent kinase (cdk)1/cyclin B complex. Subsequent p53-independent activation of the cdk-inhibitor (cdk-I) p21(WAF1/CIP1) prevented cell-cycle progression. Cdk1 induction was exploited in vivo to improve the sensitivity to CPT-11 by additional treatment with the cdk-I CYC-202. We demonstrate a gain of sensitivity to CPT-11 in a p53-mutated colon cancer model either by restoring wild-type p53 function or by sequential treatment with cdk-Is. Considering that mutations in p53 are among the most common genetic alterations in CRC, a therapeutic approach specifically targeting p53-deficient tumors could greatly improve the treatment outcomes.
Transfer Laboratory, Institut Curie-CNRS, Paris 75248, France.
Miguel
M
Abal
Rui
R
Bras-Goncalves
Jean-Gabriel
JG
Judde
Hafida
H
Fsihi
Patricia
P
De Cremoux
Daniel
D
Louvard
Henri
H
Magdelenat
Sylvie
S
Robine
Marie-France
MF
Poupon
D016203:CDC2 Protein Kinase / Q000037:antagonists & inhibitors* / Q000378:metabolism; D002166:Camptothecin / Q000031:analogs & derivatives* / Q000494:pharmacology*; D002453:Cell Cycle / Q000187:drug effects; D019926:Cyclin B / Q000378:metabolism; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D019073:HT29 Cells; D006801:Humans; D000077146:Irinotecan; D009154:Mutation / Q000235:genetics; D011687:Purines / Q000494:pharmacology; D000077546:Roscovitine; D016159:Tumor Suppressor Protein p53 / Q000172:deficiency* / Q000235:genetics / Q000378:metabolism
C493956:CDKN1A protein, human; D019926:Cyclin B; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D004791:Enzyme Inhibitors; D011687:Purines; D016159:Tumor Suppressor Protein p53; D000077546:Roscovitine; D000077146:Irinotecan; D016203:CDC2 Protein Kinase; D002166:Camptothecin