title: Gene expression variations in microsatellite stable and unstable colon cancer cells.
abstract: BACKGROUND
  Microsatellite instability (MSI) is a marker of chemoresistance, but it is associated with improved survival compared with microsatellite-stable (MSS) colon cancers. We hypothesized that MSI tumors overexpress chemoresistance-associated genes and underexpress DNA damage/repair genes. We used ultra high-throughput sequencing (UHTS) to assess the expression of representative genes in MSI and MSS colon cancer cell lines.
  
  
  METHODS
  Solexa UHTS was used to examine gene expression in HCT116 (MSI) and HT29 (MSS) cells, and normal colonic mucosa (NCM). We compared expression of 40 genes involved in chemoresistance, DNA repair, DNA damage, and drug metabolism pathways.
  
  
  RESULTS
  We observed gene expression differences between MSI and MSS cell lines in 8 out of 40 genes involved in mismatch repair (MMR), DNA repair, drug metabolism, and chemoresistance. MMR gene expression was lower in MSI cells, which is consistent with the MSI phenotype, whereas DNA repair genes were highly expressed in these cells. Genes associated with chemoresistance and drug metabolism also had increased expression in MSI cells. No difference in expression of DNA damage genes was observed between MSI and MSS cell lines.
  
  
  CONCLUSIONS
  Using UHTS gene expression analysis, we identified differential expression of genes between MSI and MSS cell lines which may account for resistance to chemotherapy in MSI tumors. UHTS expression analysis has the potential to identify genome-wide predictors of response or resistance to chemotherapy.
authors.affiliation: Department of Surgery, City of Hope Medical Center, 1500 E. Duarte Road, Duarte, CA 91010, USA.
authors.forename: Marjun P
authors.initials: MP
authors.lastname: Duldulao
authors.forename: Wendy
authors.initials: W
authors.lastname: Lee
authors.forename: Maithao
authors.initials: M
authors.lastname: Le
authors.forename: Zhenbin
authors.initials: Z
authors.lastname: Chen
authors.forename: Wenyan
authors.initials: W
authors.lastname: Li
authors.forename: Jinhui
authors.initials: J
authors.lastname: Wang
authors.forename: Harry
authors.initials: H
authors.lastname: Gao
authors.forename: Haiquing
authors.initials: H
authors.lastname: Li
authors.forename: Joseph
authors.initials: J
authors.lastname: Kim
authors.forename: Julio
authors.initials: J
authors.lastname: Garcia-Aguilar
mesh_terms: D003110:Colonic Neoplasms / Q000188:drug therapy / Q000235:genetics*; D004249:DNA Damage; D004260:DNA Repair / Q000235:genetics; D019008:Drug Resistance, Neoplasm; D005472:Fluorouracil / Q000378:metabolism / Q000494:pharmacology; D020869:Gene Expression Profiling; D005838:Genotype; D045325:HCT116 Cells; D019073:HT29 Cells; D057166:High-Throughput Screening Assays; D006801:Humans; D053842:Microsatellite Instability
chemical_list: D005472:Fluorouracil