title: Clusterin and chemotherapy sensitivity under normoxic and graded hypoxic conditions in colorectal cancer.
abstract: OBJECTIVE
  In vitro studies have shown that clusterin modulates treatment sensitivity in a number of human cancers; however, the interaction between clusterin expression and hypoxia in controlling treatment response in CRC has not previously been examined. The aim of this study was to assess the effect of clusterin overexpression in CRC cells on sensitivity to 5-fluorouracil (5-FU), oxaliplatin and FOLFOX treatment under normoxic and graded hypoxic conditions.
  
  
  METHODS
  SW480 colon cancer cells were transfected with full length Clusterin cDNA to generate a clusterin overexpressing cell line. Overexpression was confirmed by western blot analysis. The response of parental and clusterin overexpressing cells to 5-FU, oxaliplatin and FOLFOX was examined using a crystal violet-based proliferation assay under normoxic conditions, 3% and 1% hypoxic conditions. The levels of apoptosis and G2/M arrest in FOLFOX-treated cells were assessed by flow cytometry.
  
  
  RESULTS
  Under normoxic conditions, clusterin overexpressing cells were more sensitive to FOLFOX treatment (p = 0.01); under 3% and 1% hypoxic conditions, overexpressing clusterin cells were more sensitive to 5-FU, oxaliplatin and FOLFOX, p values <0.05 for all conditions. Under normoxic conditions, overexpressing clusterin cells showed significantly higher levels of apoptosis when treated with FOLFOX compared to untransfected cells; levels of G2M cells were not significantly different. Under both 3% and 1% hypoxia, the percentage of cells undergoing apoptosis following FOLFOX treatment was significantly higher in overexpressing clusterin cells.
  
  
  CONCLUSIONS
  These in vitro findings suggest that tumours expressing high levels of clusterin, particularly if hypoxic in nature, may benefit from treatments such as FOLFOX.
authors.affiliation: Centre for Colorectal Disease, St. Vincent's University Hospital, Elm Park, Dublin 4, Ireland.
authors.forename: David
authors.initials: D
authors.lastname: Kevans
authors.forename: Sheeona
authors.initials: S
authors.lastname: Gorman
authors.forename: Miriam
authors.initials: M
authors.lastname: Tosetto
authors.forename: Kieran
authors.initials: K
authors.lastname: Sheahan
authors.forename: Diarmuid
authors.initials: D
authors.lastname: O'Donoghue
authors.forename: Hugh
authors.initials: H
authors.lastname: Mulcahy
authors.forename: Jacintha
authors.initials: J
authors.lastname: O'Sullivan
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D015153:Blotting, Western; D015687:Cell Hypoxia; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D051152:Clusterin / Q000378:metabolism*; D015179:Colorectal Neoplasms / Q000378:metabolism* / Q000473:pathology; D019008:Drug Resistance, Neoplasm / Q000502:physiology*; D004797:Enzyme-Linked Immunosorbent Assay; D005434:Flow Cytometry; D006801:Humans; D014162:Transfection
chemical_list: D000970:Antineoplastic Agents; C495242:CLU protein, human; D051152:Clusterin