Clusterin and Chemotherapy Sensitivity Under Normoxic and Graded Hypoxic Conditions in Colorectal Cancer
- 109 Downloads
Background and Aims
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.
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.
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.
These in vitro findings suggest that tumours expressing high levels of clusterin, particularly if hypoxic in nature, may benefit from treatments such as FOLFOX.
KeywordsClusterin Colorectal cancer Treatment sensitivity Hypoxia
The authors declare that they have no conflict of interest or financial support to disclose in relation to this article.
- 19.Muramaki M, So A, Hayashi N, Sowery R, Miyake H, Fujisawa M, et al. Chemosensitization of gemcitabine-resistant human bladder cancer cell line both in vitro and in vivo using antisense oligonucleotide targeting the anti-apoptotic gene, clusterin. BJU Int. 2009;103(3):384–90. doi: 10.1111/j.1464-410X.2008.08098.x.PubMedCrossRefGoogle Scholar
- 25.Trougakos IP, So A, Jansen B, Gleave ME, Gonos ES. Silencing expression of the clusterin/apolipoprotein j gene in human cancer cells using small interfering RNA induces spontaneous apoptosis, reduced growth ability, and cell sensitization to genotoxic and oxidative stress. Cancer Res. 2004;64(5):1834–42.PubMedCrossRefGoogle Scholar
- 26.Bettuzzi S, Scorcioni F, Astancolle S, Davalli P, Scaltriti M, Corti A. Clusterin (SGP-2) transient overexpression decreases proliferation rate of SV40-immortalized human prostate epithelial cells by slowing down cell cycle progression. Oncogene. 2002;21(27):4328–34. doi: 10.1038/sj.onc.1205594.PubMedCrossRefGoogle Scholar
- 35.Cerniglia GJ, Pore N, Tsai JH, Schultz S, Mick R, Choe R, et al. Epidermal growth factor receptor inhibition modulates the microenvironment by vascular normalization to improve chemotherapy and radiotherapy efficacy. PLoS ONE. 2009;4(8):e6539. doi: 10.1371/journal.pone.0006539.PubMedCrossRefGoogle Scholar
- 40.Wilson C, Wilson T, Johnston PG, Longley DB, Waugh DJ. Interleukin-8 signaling attenuates TRAIL- and chemotherapy-induced apoptosis through transcriptional regulation of c-FLIP in prostate cancer cells. Mol Cancer Ther. 2008;7(9):2649–61. doi: 10.1158/1535-7163.MCT-08-0148.PubMedCrossRefGoogle Scholar
- 47.Albert JM, Gonzalez A, Massion PP, Chen H, Olson SJ, Shyr Y, et al. Cytoplasmic clusterin expression is associated with longer survival in patients with resected non small cell lung cancer. Cancer Epidemiol Biomarkers Prev. 2007;16(9):1845–51. doi: 10.1158/1055-9965.EPI-07-0146.PubMedCrossRefGoogle Scholar