Autophagy pathways in glioblastoma.

Glioma cells are more likely to respond to therapy through autophagy than through apoptosis. The most efficacious cytotoxic drugs employed in glioma therapy, such as temozolomide and rapamycin, induce autophagy. Oncolytic adenoviruses, which will soon be tested in patients with gliomas at the University of Texas M. D. Anderson Cancer Center, also induce autophagy. Autophagy in gliomas thus represents a promising mechanism that may lead to new glioma therapies. In this chapter, we present the methods for studying autophagy in glioma cells, including assessment of in vitro cellular markers acidic vesicle organelles, and green fluorescent protein (GFP)-LC3 punctation; biochemical markers LC3-I/II conversion, p62 degradation, Atg12-Atg5 accumulation, and p70S6K dephosphorylation; and ultrastucture of the autophagosomes. In addition, we will address how LC3B and Atg5 up-regulation during autophagy can be examined through immunostaining in treated tumors and the potential of these proteins for use as surrogate markers to monitor therapeutic effects in clinical trials. Finally, we will discuss the challenges of studying autophagy in gliomas and the future directions of such use.