Autophagy, a major adaptation pathway shaping cancer cell death and anticancer immunity responses following photodynamic therapy

Autophagy is a major catabolic pathway in a eukaryotic cell, employed for cellular self-degradation of obsolete or damaged cytoplasmic components serving as a major quality control and recycling mechanism that supports cell survival. Autophagy is fundamentally a cytoprotective and pro-survival process yet in general, it has become clear through a number of studies that autophagy has an exceedingly contextual role in cancer biology; conditional on which phase, location or type of oncogenic trigger and/or therapy is under consideration, the role of autophagy could end up fluctuating from pro- to anti-tumourigenic. Numerous studies have revealed that, contingent on the photosensitiser under consideration, autophagy triggered by PDT either adds to therapy resistance (by suppressing cell death) or vulnerability (by enabling autophagic cell death). Beyond cell death regulation, cancer cell-associated autophagy also supports resistance against PDT by reducing anticancer immune effector mechanisms. In this review, we have concisely described the state-of-the-art and the prevailing gap-in-knowledge vis-à-vis the role of PDT-triggered autophagy in cancer therapy resistance or susceptibility.