Autophagy as a way to remove DNA lesions.

Abstract

Type I topoisomerases (TOP1) are critical to remove the topological stress when DNA double strands are unwound. The TOP1 cleavage complexes (TOP1cc) are normally transient, and the stabilization of TOP1cc by its inhibitors, such as camptothecin (CPT), may lead to DNA damage and become cytotoxic. The proteasome pathway degrades trapped TOP1, which is necessary for the repair machinery to gain access to the DNA; however, this process is mainly described when the CPT concentration is high, at levels which are clinically unachievable. In a recently published study, Lascaux et al. identify macroautophagy/autophagy as a new pathway to remove DNA lesions upon clinically relevant low-dose CPT treatment. The autophagy receptor TEX264 binds to TOP1 and brings this protein and its bound DNA fragments to the phagophore; subsequently, they are ultimately delivered to the lysosome for degradation. This study demonstrates the role of autophagy in maintaining genome stability from a new perspective and reveals potential targets to deal with the resistance to TOP1cc inhibitors during cancer treatment.