title: Molecular mechanisms of action and prediction of response to oxaliplatin in colorectal cancer cells.
abstract: The platinum compound oxaliplatin has been shown to be an effective chemotherapeutic agent for the treatment of colorectal cancer. In this study, we investigate the molecular mechanisms of action of oxaliplatin to identify means of predicting response to this agent. Exposure of colon cancer cells to oxaliplatin resulted in G2/M arrest and apoptosis. Immunofluorescent staining demonstrated that the apoptotic cascade initiated by oxaliplatin is characterised by translocation of Bax to the mitochondria and cytochrome c release into the cytosol. Oxaliplatin treatment resulted in caspase 3 activation and oxaliplatin-induced apoptosis was abrogated by inhibition of caspase activity with z-VAD-fmk, but was independent of Fas/FasL association. Targeted inactivation of Bax or p53 in HCT116 cells resulted in significantly increased resistance to oxaliplatin. However, the mutational status of p53 was unable to predict response to oxaliplatin in a panel of 30 different colorectal cancer cell lines. In contrast, the expression profile of these 30 cell lines, assessed using a 9216-sequence cDNA microarray, successfully predicted the apoptotic response to oxaliplatin. A leave-one-out cross-validation approach was used to demonstrate a significant correlation between experimentally observed and expression profile predicted apoptosis in response to clinically achievable doses of oxaliplatin (R=0.53; P=0.002). In addition, these microarray experiments identified several genes involved in control of apoptosis and DNA damage repair that were significantly correlated with response to oxaliplatin.
authors.affiliation: Oncology Department, Albert Einstein Cancer Center, Montefiore Medical Center, 111 East 210th St, Bronx, NY 10467, USA. diego.arango@helsinki.fi
authors.forename: D
authors.initials: D
authors.lastname: Arango
authors.forename: A J
authors.initials: AJ
authors.lastname: Wilson
authors.forename: Q
authors.initials: Q
authors.lastname: Shi
authors.forename: G A
authors.initials: GA
authors.lastname: Corner
authors.forename: M J
authors.initials: MJ
authors.lastname: Arañes
authors.forename: C
authors.initials: C
authors.lastname: Nicholas
authors.forename: M
authors.initials: M
authors.lastname: Lesser
authors.forename: J M
authors.initials: JM
authors.lastname: Mariadason
authors.forename: L H
authors.initials: LH
authors.lastname: Augenlicht
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D053148:Caspase 3; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism; D002455:Cell Division / Q000187:drug effects; D015179:Colorectal Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D045304:Cytochromes c / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D019008:Drug Resistance, Neoplasm; D004789:Enzyme Activation / Q000187:drug effects; D016195:G2 Phase / Q000187:drug effects; D020869:Gene Expression Profiling; D006801:Humans; D008928:Mitochondria; D009944:Organoplatinum Compounds / Q000494:pharmacology*; D000077150:Oxaliplatin; D011237:Predictive Value of Tests; D021381:Protein Transport; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000037:antagonists & inhibitors / Q000378:metabolism; D014407:Tumor Cells, Cultured; D016159:Tumor Suppressor Protein p53 / Q000037:antagonists & inhibitors / Q000378:metabolism; D051028:bcl-2-Associated X Protein
chemical_list: D000970:Antineoplastic Agents; C494826:BAX protein, human; D061945:Caspase Inhibitors; D009944:Organoplatinum Compounds; D019253:Proto-Oncogene Proteins c-bcl-2; D016159:Tumor Suppressor Protein p53; D051028:bcl-2-Associated X Protein; D000077150:Oxaliplatin; D045304:Cytochromes c; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases