The Proliferative Response of HeLa Cells to 2-Deoxy-D-Glucose Under Hypoxic or Anoxic Conditions: An Analogue for Studying some Properties of In Vivo Solid Cancers

Abstract

Background: Hypoxic cancer cells located beyond the diffusion path of sufficient oxygen are considered a nidus of therapeutic failure. Due to the dependence of many malignantly transformed cells on glycolysis for metabolic energy, inhibiting this and other sources of energy should seriously reduce cell viability and proliferation, additively or even synergistically. Materials and Methods: To try and duplicate in vitro some of the features of in vivo cancer cells likely to resist therapy, HeLa cells were incubated with sub-lethal concentrations of 2-deoxy-D-glucose under aerobic, hypoxic or virtually anoxic conditions, verified by increased synthesis of Hif-1α, and their replication and survival determined. MK 886, an inhibitor of mitochondrial function was used to estimate participation of that organelle in energy metabolism. Results: Culture of cervical cancer-derived HeLa cells with 2-deoxy-D-glucose under these restrictive conditions did not reduce their proliferation or viability to the expected extent. Their surprisingly robust survival included the anticipated increase in dependence upon glycolysis and implied a likely entrainment of other constitutive and possibly facultative energy sources and pathways. Increased synthesis of Hif-1α, increased binding to its consensus sequence and reduced inhibition from MK 886 in cells under oxygen-deficient environments confirmed the presence of restrictive conditions. Conclusion: Efforts to suppress HeLa cell survival by reducing glucose consumption and metabolic energy from ambient oxygen may require inhibition of multiple energy sources, possibly not all of them identified. In vitro assessment of agents directed against sources of metabolic energy or of other therapeutic agents against these or additional potential targets should include studies under hypoxia and relative anoxia. In this way, the possible responses of in vivo hypoxic or anoxic cancer cells believed to contribute to therapeutic failure may be estimated.