Treatment Response in GBM Cells Under Normoxic and Hypoxic Conditions

Abstract

Abstract AIMS Glioblastomas (GBMs) are characterised by highly hypoxic regions and the ability to invade into healthy brain tissue promoting tumour dissemination and recurrence; the development of novel anti-migratory inhibitors to target cell invasion and recurrence must consider varying treatment responses in this tumour background. As proof of principle we investigated the anti-migratory activity of two, previously characterised, small molecule inhibitors under normoxic and hypoxic conditions. We hypothesised that anti-migratory drug activity is dependent on hypoxia levels. METHOD Glioma cell line U251 was exposed to BIO-indirubin and Y-27632 alone or in combination and activity was assessed in 2D scratch assays under normoxic (21% O2) and hypoxic (0.1% O2) conditions. Live cell imaging was performed and analysis was carried out using ImageJ. RESULTS Treatment with BIO, Y-27632 or in combination had a statistically significant effect on the inhibition of migration in normoxia and hypoxia (p=0.01); BIO inhibited migration and Y-27632 promoted migration under normoxia, whereas BIO maintained the anti-migratory effect under hypoxia, the effect of Y-27632 was switched towards anti-migratory activity and combination treatment potentiated. The effect of Y-27632 was concomitant with a phenotypic shift in cells under hypoxia from highly elongated to possessing shorter extensions. CONCLUSION An anti-migratory effect of Y-27632 on cell migration was induced under hypoxic conditions suggesting that the adoption of amoeboid migration by the cells allowed targeting migratory pathways under the control of RhoA and ROCK. This confirms that candidate drug activity must be assessed under both conditions to be considered as drugs complementary to chemotherapy as potential novel treatment option.