Bovine seminal ribonuclease triggers Beclin1-mediated autophagic cell death in pancreatic cancer cells

Among the large number of variants belonging to the pancreatic-type secretory ribonuclease (RNase) superfamily,bovine pancreatic ribonuclease (RNase A) is the proto-type and bovine seminal RNase (BS-RNase) representsthe unique natively dimeric member. In the present manuscript, we evaluate the anti-tumoral property of theseRNases in pancreatic adenocarcinoma cell lines and in nontumorigenic cells as normal control.We demonstratethat BS-RNase stimulates a strong anti-proliferative and pro-apoptotic effect in cancer cells, while RNase A islargely ineffective. Notably, we reveal for the first time that BS-RNase triggers Beclin1-mediated autophagic cancercell death, providing evidences that high proliferation rate of cancer cellsmay render them more susceptibleto autophagy by BS-RNase treatment.Notably, to improve the autophagic response of cancer cells to BS-RNaseweused two different strategies: the more basic (as compared to WT enzyme) G38Kmutant of BS-RNase, known tointeract more strongly than wt with the acidic membrane of cancer cells, or BS-RNase oligomerization(tetramerization or formation of larger oligomers). Both mutant BS-RNase and BS-RNase oligomers potentiatedautophagic cell death as compared to WT native dimer of BS-RNase, while the various RNase A oligomersremained completely ineffective. Altogether, our results shed more light on the mechanisms lying at the basisof BS-RNase antiproliferative effect in cancer cells, and support its potential use to develop new anti-cancerstrategies.