Predicting Efficacy of Cancer Cell Killing under Hypoxic Conditions with Single Cell DNA Damage Assay

The activity of anticancer drugs determined under normal conditions cannot accurately reflect true drug efficacy in a patient, as a tumor is often under low oxygen (hypoxia) conditions. In addition, patient responses to the same therapy can be drastically different due to tumor heterogeneity. This paper describes the use of single cell halo assay for detection and quantification of DNA damage induced by anticancer drugs or radiation under hypoxic conditions. By combining classical halo assay and state-of-the-art microfabrication techniques, this single cell approach allows drug and radiation responses of cancer cells to be determined without population interference. The results from single cell assay indicate a diminished level of DNA damage at hypoxic conditions compared with those at normal conditions at the same drug concentrations or radiation dose, suggesting in vitro preclinical studies of drug and radiation activity can be performed under conditions that mimic physiological conditions of tumors and without population interference.