PT  - JOURNAL ARTICLE
AU  - Louisa M. Brown
AU  - Rachel L. Cowen
AU  - Camille Debray
AU  - Amanda Eustace
AU  - Janine T. Erler
AU  - Freda C. D. Sheppard
AU  - Catriona A. Parker
AU  - Ian J. Stratford
AU  - Kaye J. Williams
TI  - Reversing Hypoxic Cell Chemoresistance in Vitro Using Genetic and Small Molecule Approaches Targeting Hypoxia Inducible Factor-1
AID  - 10.1124/mol.105.015743
DP  - 2006 Feb 01
TA  - Molecular Pharmacology
PG  - 411--418
VI  - 69
IP  - 2
4099  - http://molpharm.aspetjournals.org/content/69/2/411.short
4100  - http://molpharm.aspetjournals.org/content/69/2/411.full
SO  - Mol Pharmacol2006 Feb 01; 69
AB  - The resistance of hypoxic cells to conventional chemotherapy is well documented. Using both adenovirus-mediated gene delivery and small molecules targeting hypoxia-inducible factor-1 (HIF-1), we evaluated the impact of HIF-1 inhibition on the sensitivity of hypoxic tumor cells to etoposide. The genetic therapy exploited a truncated HIF-1α protein that acts as a dominant-negative HIF-1α (HIF-1α-no-TAD). Its functionality was validated in six human tumor cell lines using HIF-1 reporter assays. An EGFP-fused protein demonstrated that the dominant-negative HIF-1α was nucleus-localized and constitutively expressed irrespective of oxygen tension. The small molecules studied were quinocarmycin monocitrate (KW2152), its analog 7-cyanoquinocarcinol (DX-52-1), and topotecan. DX-52-1 and topotecan have been previously established as HIF-1 inhibitors. HT1080 and HCT116 cells were treated with either AdHIF-1α-no-TAD or nontoxic concentrations (0.1 μM; <IC10) of KW2152 and DX-52-1 and exposed to etoposide in air or anoxia (<0.01% oxygen). Topotecan inhibited HIF-1 activity only at cytotoxic concentrations and was not used in the combination study. Etoposide IC50 values in anoxia were 3-fold higher than those in air for HT1080 (2.2 ± 0.3 versus 0.7 ± 0.2 μM) and HCT116 (9 ± 4 versus 3 ± 2 μM) cells. KW2152 and DX-52-1 significantly reduced the anoxic etoposide IC50 in HT1080 cells, whereas only KW2152 yielded sensitization in HCT116 cells. In contrast, AdHIF-1α-no-TAD (multiplicity of infection 50) ablated the anoxic resistance in both cell lines (IC50 values: HT1080, 0.7 ± 0.04 μM; HCT116, 3 ± 1 μM). HIF-1α-no-TAD expression inhibited HIF-1-mediated down-regulation of the proapoptotic protein Bid under anoxia. These data support the potential development of HIF-1 targeted approaches in combination with chemotherapy, where hypoxic cell resistance contributes to treatment failure.