Autophagy mediated lipid catabolism facilitates glioma progression to overcome bioenergetic crisis

Activation of mTORC1 plays a significant role in cancer development and progression. However, the metabolic mechanisms to sustain mTORC1 activation of cancer cells within stressed environments are still under-appreciated. We recently revealed high autophagy activity in tumour cells with mTORC1 hyper-activation. Nevertheless, the functions and mechanisms of autophagy in regulating mTORC1 in glioma are not studied. Using glioma patient database and human glioma cells, we assessed the mechanisms and function of selective autophagy to sustain mTORC1 hyper-activation in glioma. We revealed a strong association of altered mRNA levels in mTORC1 upstream and downstream genes with prognosis of glioma patients. Our results indicated that autophagy-mediated lipid catabolism was essential to sustain mTORC1 activity in glioma cells under energy stresses. We found that autophagy inhibitors or fatty acid oxidation (FAO) inhibitors in combination with 2-Deoxy-D-glucose (2DG) decreased energy production and survival of glioma cells in vitro. Consistently, inhibition of autophagy or FAO inhibitors with 2DG effectively suppressed the progression of xenografted glioma with hyper-activated mTORC1. This study established an autophagy/lipid degradation/FAO/ATP generation pathway, which might be used in brain cancer cells under energy stresses to maintain high mTORC1 signalling for tumour progression.