Contribution of the cyclin-dependent kinase inhibitor p27KIP1 to the confluence-dependent resistance of HT29 human colon carcinoma cells.
We have previously shown that growth of HT29 human colorectal cancer cells at confluence increased their resistance to the cytotoxic agent cisplatin. This study further explores the mechanisms of this resistance phenotype. DNA platination induced by cisplatin exposure is slightly reduced by confluence. However, at an equivalent DNA platination level, non-confluent cells accumulate in the G2/M phase of the cell cycle, demonstrate aberrant mitotic figures and die by apoptosis, while confluent cells progress slowly through the cell cycle, do not reach mitosis and are more resistant to drug-induced cell death. At a molecular level, cisplatin enhances cyclin B and p34cdc2 levels and histone H1 kinase activity in non-confluent, but not in confluent, cells. Furthermore, when HT29 cells reach confluence, expression of the cyclin-dependent kinase inhibitor p27Kip1 increases and cells accumulate in the G0/G1 phase of the cell cycle. Transfection-mediated over-expression of p27Kip1 in non-confluent HT29 cells decreases the cytotoxic activity of cisplatin as well as its ability to trigger apoptosis. Non-confluent HT29 cells over-expressing p27Kip1 are also more resistant to doxorubicin, etoposide and 5-fluorouracil. Our results suggest that p27Kip1 contributes to the confluence-dependent resistance phenotype.
CJF INSERM 94-08, Biology and Cancer Therapy Group, Faculty of Medicine and Pharmacy, Dijon, France. mtboitr@u-bourgogne.fr
M T
MT
Dimanche-Boitrel
O
O
Micheau
A
A
Hammann
M
M
Haugg
B
B
Eymin
B
B
Chauffert
E
E
Solary
D017209:Apoptosis / Q000187:drug effects; D002448:Cell Adhesion; D002453:Cell Cycle / Q000187:drug effects / Q000502:physiology*; D018797:Cell Cycle Proteins; D002460:Cell Line; D002945:Cisplatin / Q000633:toxicity; D050760:Cyclin-Dependent Kinase Inhibitor p27; D018844:Cyclin-Dependent Kinases / Q000037:antagonists & inhibitors*; D019008:Drug Resistance, Neoplasm; D004791:Enzyme Inhibitors / Q000378:metabolism; D016195:G2 Phase; D016158:Genes, p53; D019073:HT29 Cells; D006801:Humans; D008869:Microtubule-Associated Proteins / Q000096:biosynthesis / Q000378:metabolism*; D008938:Mitosis; D017354:Point Mutation; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000378:metabolism; D014162:Transfection; D016159:Tumor Suppressor Protein p53 / Q000235:genetics; D025521:Tumor Suppressor Proteins
D018797:Cell Cycle Proteins; D004791:Enzyme Inhibitors; D008869:Microtubule-Associated Proteins; D011994:Recombinant Proteins; D016159:Tumor Suppressor Protein p53; D025521:Tumor Suppressor Proteins; D050760:Cyclin-Dependent Kinase Inhibitor p27; D018844:Cyclin-Dependent Kinases; D002945:Cisplatin