Irinotecan induces senescence and apoptosis in colonic cells in vitro.
Irinotecan (CPT-11) is topoisomerase I inhibitor used in the treatment of disseminated colorectal cancer. In colon cancer cells it induces DNA damage which leads to cytotoxicity with ensuing apoptosis or premature senescence. Despite its clinical use and efficiency in malignant colonocytes, its effects in normal colonic cells are relatively underexplored. In this work we report that CPT-11 induces dose-dependent cytotoxicity which results in apoptosis and premature senescence whose occurrence nevertheless varies in relation to the type of exposed cells. In normal colonic epithelial cells (NCM) the prevailing type of response is apoptosis whereas in normal colonic fibroblasts (NCF) it is premature senescence. Further analyses showed that CPT-11 induced in both types of cells DNA damage and activated stress response pathways including p53 and p16 but with varying activity of stress kinase p38 and selected stress-associated microRNAs. Epithelial cells upregulated the expression of p53, which was subsequently specifically phosphorylated, massively activated p38 and initiated mitochondrial, caspase-dependent apoptosis. These events occurred in the presence of moderately increased expression of miR-34a only. Conversely, in colonic fibroblasts p38 was only moderately activated, p53 as well as p16 expressions were upregulated in the presence of increased expression of miR-34a, miR-128a and miR-449a. Caspase-dependent apoptosis was found only in a minority of treated cells and the premature senescence phenotype was prevailing. Specific inhibition further proved that p53-dependent as well as independent mechanisms might be responsible for these cell type-specific differences.
Department of Medical Biology and Genetics, Charles University in Prague, Faculty of Medicine in Hradec Kralove, Simkova 870, Hradec Kralove 500 38, Czech Republic. rudolf@lfhk.cuni.cz
Emil
E
Rudolf
Stanislav
S
John
Miroslav
M
Cervinka
D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D002166:Camptothecin / Q000031:analogs & derivatives* / Q000494:pharmacology; D002277:Carcinoma / Q000235:genetics / Q000378:metabolism*; D016922:Cellular Senescence / Q000187:drug effects; D003106:Colon / Q000166:cytology*; D015179:Colorectal Neoplasms; D019941:Cyclin-Dependent Kinase Inhibitor p16; D004249:DNA Damage; D005347:Fibroblasts / Q000187:drug effects*; D005786:Gene Expression Regulation / Q000187:drug effects; D055785:Gene Knockdown Techniques; D045325:HCT116 Cells; D006801:Humans; D000077146:Irinotecan; D020928:Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism
D000972:Antineoplastic Agents, Phytogenic; C000614131:CDKN2A protein, human; D019941:Cyclin-Dependent Kinase Inhibitor p16; D009363:Neoplasm Proteins; D016159:Tumor Suppressor Protein p53; D000077146:Irinotecan; D020928:Mitogen-Activated Protein Kinases; D002166:Camptothecin