Approaches and Protocols to Analyze Autophagy and Its Role in Death of Apoptosis-Resistant Senescent Tumor Cells

Anticancer therapy is complicated by the ability of malignant cells to activate cytoprotective autophagy that rescues treated cells. This protocol describes methods for analysis of autophagic process in apoptosis-resistant tumor cells treated with damaging agents. Induction of autophagy in these cells can activate apoptotic death. Protocol provides methods for Western blotting, immunofluorescent analysis, and transfection of cells with fluorescent protein-tagged LC3-encoding plasmids to analyze autophagy. Different approaches to change autophagy in tumor cells are suggested. A special approach is connected with induction of cellular senescence. Senescent cells, which are resistant to apoptosis, are vulnerable to certain damaging agents, in particular, to kinase inhibitors. Methods to induce and analyze senescence are considered. They include detection of proliferation arrest by different ways, mTORC1 activity assay and fluorescent analysis of mTORC1 and lysosome localization as a novel senescence hallmark. Incapability of senescent cells to complete autophagy after damage allows to force them to apoptosis. To demonstrate apoptotic cell death, analysis of caspase activity, Annexin V-FITC binding, DNA fragmentation, and mitochondria and lysosome damage are suggested. The methods described can be applied in studies aimed on developing different strategies of tumor cell elimination through changing autophagy.