Xenophagy: A battlefield between host and microbe, and a possible avenue for cancer treatment.

In eukaryotes, xenophagy is defined as a type of selective macroautophagy/autophagy that is used for eliminating invading pathogens. In contrast to other types of selective autophagy, such as mitophagy, pexophagy and ribophagy, xenophagy is used by eukaryotes for targeting microbes-hence the prefix "xeno" meaning "other" or "foreign"-that have infected a host cell, leading to their lysosomal degradation. This unique characteristic links xenophagy to antibacterial and antiviral defenses, as well as the immune response. Furthermore, recent studies suggest a complicated role of xenophagy in cancer, through either suppressing tumorigenesis or promoting survival of established tumors. In this issue, Sui et al. summarize previous and current studies of xenophagy and consider them in the context of anticancer treatment.