In Vitro Assay for the Assessment of Oxygen Depletion Triggers in Human Cell Lines, Associated with Improving Responses to Cancer Therapy.

Tumors are usually associated with oxygen-deficient regions (hypoxia) which results from reduced and disorganized intratumoral vasculature, increased diffusion distances, and growing tumor masses. The proteomic and metabolomic landscape of the hypoxic cells is reprogrammed through hypoxia-induced transcription factor 1 which is activated in hypoxic conditions and is inactive when oxygen is abundant. This transcription factor has also been shown to inhibit or even reverse cell differentiation. Hypoxia impedes chemotherapy as it hampers the formation of cytotoxic free radicals due to the lesser availability of molecular oxygen. The metastatic and invasive attributes of cancer cells in hypoxic conditions are exacerbated, which results in poor therapeutic outcomes. Various cell-based assays for measuring hypoxia have been developed which give an estimate of the hypoxic state of cancer cells. Prior knowledge of these assays will improve the efficacy of the treatment regimens for cancers. This article provides exhaustive information on the hypoxia-based assays which are sensitive, robust, reliable, and give easy readout with choice of cell type for these assays may be dictated by the procedural or endpoint selection.