SIDT2 RNA transporter promotes lung and gastrointestinal tumor development
RNautophagy is a newly-described type of selective autophagy whereby cellular RNAs are transported into lysosomes for degradation. This process involves the transmembrane protein SIDT2, which transports double-stranded RNA (dsRNA) across the endolysosomal membrane. We previously demonstrated that SIDT2 is a transcriptional target of p53, but its role in tumorigenesis - if any - is unclear. Unexpectedly, we show here that Sidt2-/- mice with concurrent oncogenic KrasG12D activation develop significantly fewer tumors than littermate controls in a mouse model of lung adenocarcinoma (LUAD). Consistent with this observation, loss of SIDT2 also leads to enhanced survival and delayed tumor development in an Apcmin/+ mouse model of intestinal cancer. Within the intestine, Apcmin/+;Sidt2-/- mice display accumulation of dsRNA in association with increased phosphorylation of eIF2 and JNK as well as elevated rates of apoptosis. Taken together, our data demonstrate a role for SIDT2 - and by extension RNautophagy - in promoting tumor development.