RT Journal Article
SR Electronic
T1 Reversing Hypoxic Cell Chemoresistance in Vitro Using Genetic and Small Molecule Approaches Targeting Hypoxia Inducible Factor-1
JF Molecular Pharmacology
JO Mol Pharmacol
FD American Society for Pharmacology and Experimental Therapeutics
SP 411
OP 418
DO 10.1124/mol.105.015743
VO 69
IS 2
A1 Louisa M. Brown
A1 Rachel L. Cowen
A1 Camille Debray
A1 Amanda Eustace
A1 Janine T. Erler
A1 Freda C. D. Sheppard
A1 Catriona A. Parker
A1 Ian J. Stratford
A1 Kaye J. Williams
YR 2006
UL http://molpharm.aspetjournals.org/content/69/2/411.abstract
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.