title: Gene expression profile of colon cancer cell lines treated with SN-38.
abstract: OBJECTIVE
  Colorectal cancer is the third most common form of cancer in the industrial countries. Due to advances regarding the treatments, primarily development of improved surgical methods and the ability to make the earlier diagnosis, the mortality has remained constant during the past decades even though the incidence in fact has increased. To improve chemotherapy and enable personalised treatment, the need of biomarkers is of great significance. In this study, we evaluated the gene expression profiles of the colon cancer cell lines treated with SN-38, the active metabolite of topoisomerase-1 inhibitor irinotecan which leads to cell cycle arrest and apoptosis.
  
  
  METHODS
  The study included 3 colon cancer cell lines: KM12C, KM12SM and KM12l4a. The 3 cell lines were treated with SN-38, and samples were obtained after 24 and 48 hour treatments. The gene expression analyses were performed using oligonucleotide microarrays comprising of approximately 27,000 spots where the untreated controls were compared to the SN-38-treated samples.
  
  
  RESULTS
  Unsupervised clustering clearly distinguished the treated cell lines from the untreated. Supervised analysis identified 3,974 significant genes (p = 0.05) differentiating the treated samples from the untreated, majority of which were down-regulated after treatment. The top-ranked down-regulated genes in the treated cell lines included those related to receptor and kinase activity, signal transduction, apoptosis, RNA processing, protein metabolism and transport, cell cycle and transcription. A smaller number of genes were up-regulated in the cell lines after treatment and included genes involved in apoptosis, transcription, development and differentiation.
  
  
  CONCLUSIONS
  These results demonstrate that the expression of the genes involved in cell proliferation and apoptosis as well as RNA, DNA and protein metabolism were affected by SN-38. The impact of certain genes on colorectal cancer development needs to be further evaluated; however, these results could serve as a basis for further studies in order to find targets for irinotecan treatment.
authors.affiliation: Division of Surgery and Clinical Oncology, Department of Clinical and Experimental Medicine, Linköping University, Linköping, Sweden. asa.wallin@liu.se
authors.forename: A
authors.initials: A
authors.lastname: Wallin
authors.forename: P
authors.initials: P
authors.lastname: Francis
authors.forename: M
authors.initials: M
authors.lastname: Nilbert
authors.forename: J
authors.initials: J
authors.lastname: Svanvik
authors.forename: X-F
authors.initials: XF
authors.lastname: Sun
mesh_terms: D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology*; D002166:Camptothecin / Q000031:analogs & derivatives* / Q000494:pharmacology; D045744:Cell Line, Tumor; D003110:Colonic Neoplasms / Q000235:genetics / Q000378:metabolism*; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D000077146:Irinotecan; D020411:Oligonucleotide Array Sequence Analysis
chemical_list: D000972:Antineoplastic Agents, Phytogenic; D000077146:Irinotecan; D002166:Camptothecin