Roberts, D.L. and Williams, K.J. and Cowen, R.L. and Barathova, M. and Eustace, A.J. and Brittain-Dissont, S. and Tilby, M.J. and Pearson, D.G. and Ottley, C.J. and Stratford, I.J. and Dive, C. (2009) 'Contribution of HIF-1 and drug penetrance to oxaliplatin resistance in hypoxic colorectal cancer cells.', British journal of cancer., 101 (8). pp. 1290-1297.
Background: Hypoxia is as an indicator of poor treatment outcome. Consistently, hypoxic HCT116 colorectal cancer cells are resistant to oxaliplatin, although the mechanistic basis is unclear. This study sought to investigate the relative contribution of HIF-1 (hypoxia-inducible factor-1)-mediated gene expression and drug penetrance to oxaliplatin resistance using three-dimensional spheroids. Methods: Hypoxia-inducible factor-1α function was suppressed by the stable expression of a dominant-negative form in HCT116 cells (DN). Cells were drug exposed as monolayer or multicellular spheroid cultures. Cells residing at differing oxygenation status were isolated from Hoechst 33342-treated spheroids using flow cytometry. Sub-populations were subjected to clonogenic survival assays and to Inductively-Coupled Plasma Mass Spectroscopy to determine oxaliplatin uptake. Results: In spheroids, a sensitivity gradient (hypoxic<aerobic) was revealed by survival assays and this correlated with levels of platinum-bound DNA. The resistance of hypoxic sub-populations exceeded relative changes in adduct levels, implicating factors other than drug penetrance in cell response. Dominant-negative monolayer cells showed no resistance to oxaliplatin in hypoxia and spheroids; the relative resistance of hypoxic compared with aerobic sub-populations was reduced compared with those from controls. Conclusion: Overall, data show that drug penetration, DNA damage levels and HIF-1-dependent processes, all contribute to the resistance of hypoxic cells to oxaliplatin.
|Additional Information:||Full-text available at: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2768443|
|Keywords:||Hypoxia, Apoptosis, DNA damage, Oxaliplatin, Tumour spheroids, Bioavailability.|
|Full text:||Full text not available from this repository.|
|Publisher Web site:||http://dx.doi.org/10.1038/sj.bjc.6605311|
|Date accepted:||No date available|
|Date deposited:||No date available|
|Date of first online publication:||October 2009|
|Date first made open access:||No date available|
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