Aurora kinase inhibition triggers senescence in human melanoma cells

Phenotypically, there is a heterogeneous response of cancer cells to chemotherapy or targeted therapy. While therapeutically much attention is focused on cell death, there is growing evidence suggesting that a subpopulation of cancer cells undergo therapy-induced senescence. Depending on the therapy, dose and timing, senescence may be a dominant phenotype over cell death. An integrated FACS approach identified two types of therapy-induced senescence in human melanoma cells, irreversible senescence induced by Aurora kinase inhibition vs. transient senescence induced by B-RAF kinase inhibition. Autophagy and ER stress response precede and are required for therapy-induced senescence in cancer cells, mirroring their functions in normal cells undergoing oncogene-induced senescence. Importantly, autophagy serves a survival pathway for senescent cancer cells. Antagonizing autophagy converts therapy-induced senescence into cell death but paradoxically promotes cell proliferation or quiescence. Our work calls for a rationale-based design of combination therapy for cancer treatment that should lead to a greater synergy. There are three or four replicates per treatment per time point.