title: KRAS mutation is a predictor of oxaliplatin sensitivity in colon cancer cells.
abstract: Molecular biomarkers to determine the effectiveness of targeted therapies in cancer treatment have been widely adopted in colorectal cancer (CRC), but those to predict chemotherapy sensitivity remain poorly defined. We tested our hypothesis that KRAS mutation may be a predictor of oxaliplatin sensitivity in CRC. KRAS was knocked-down in KRAS-mutant CRC cells (DLD-1(G13D) and SW480(G12V)) by small interfering RNAs (siRNA) and overexpressed in KRAS-wild-type CRC cells (COLO320DM) by KRAS-mutant vectors to generate paired CRC cells. These paired CRC cells were tested by oxaliplatin, irinotecan and 5FU to determine the change in drug sensitivity by MTT assay and flow cytometry. Reasons for sensitivity alteration were further determined by western blot and real-time quantitative reverse transcriptase polymerase chain reaction (qRT -PCR). In KRAS-wild-type CRC cells (COLO320DM), KRAS overexpression by mutant vectors caused excision repair cross-complementation group 1 (ERCC1) downregulation in protein and mRNA levels, and enhanced oxaliplatin sensitivity. In contrast, in KRAS-mutant CRC cells (DLD-1(G13D) and SW480(G12V)), KRAS knocked-down by KRAS-siRNA led to ERCC1 upregulation and increased oxaliplatin resistance. The sensitivity of irinotecan and 5FU had not changed in the paired CRC cells. To validate ERCC1 as a predictor of sensitivity for oxaliplatin, ERCC1 was knocked-down by siRNA in KRAS-wild-type CRC cells, which restored oxaliplatin sensitivity. In contrast, ERCC1 was overexpressed by ERCC1-expressing vectors in KRAS-mutant CRC cells, and caused oxaliplatin resistance. Overall, our findings suggest that KRAS mutation is a predictor of oxaliplatin sensitivity in colon cancer cells by the mechanism of ERCC1 downregulation.
authors.affiliation: Department of Oncology, National Taiwan University Hospital, Taipei, Taiwan.
authors.forename: Yu-Lin
authors.initials: YL
authors.lastname: Lin
authors.forename: Jau-Yu
authors.initials: JY
authors.lastname: Liau
authors.forename: Shan-Chi
authors.initials: SC
authors.lastname: Yu
authors.forename: Da-Liang
authors.initials: DL
authors.lastname: Ou
authors.forename: Liang-In
authors.initials: LI
authors.lastname: Lin
authors.forename: Li-Hui
authors.initials: LH
authors.lastname: Tseng
authors.forename: Yih-Leong
authors.initials: YL
authors.lastname: Chang
authors.forename: Kun-Huei
authors.initials: KH
authors.lastname: Yeh
authors.forename: Ann-Lii
authors.initials: AL
authors.lastname: Cheng
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects / Q000235:genetics; D002166:Camptothecin / Q000031:analogs & derivatives / Q000494:pharmacology; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects / Q000235:genetics; D003110:Colonic Neoplasms / Q000235:genetics* / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D004720:Endonucleases / Q000235:genetics / Q000378:metabolism; D005472:Fluorouracil / Q000494:pharmacology; D006801:Humans; D000077146:Irinotecan; D009154:Mutation; D009944:Organoplatinum Compounds / Q000494:pharmacology*; D000077150:Oxaliplatin; D011518:Proto-Oncogene Proteins / Q000235:genetics* / Q000378:metabolism; D016283:Proto-Oncogene Proteins p21(ras); D018631:ras Proteins / Q000235:genetics* / Q000378:metabolism
chemical_list: D000970:Antineoplastic Agents; D004268:DNA-Binding Proteins; C117307:KRAS protein, human; D009944:Organoplatinum Compounds; D011518:Proto-Oncogene Proteins; D000077150:Oxaliplatin; D000077146:Irinotecan; C071447:ERCC1 protein, human; D004720:Endonucleases; D016283:Proto-Oncogene Proteins p21(ras); D018631:ras Proteins; D005472:Fluorouracil; D002166:Camptothecin