LV-320 is a potent and uncompetitive ATG4B inhibitor with an IC50 of 24.5 µM and a Kd of 16 µM. LV-320 inhibits ATG4B enzymatic activity, blocks autophagic flux in cells, and is stable, non-toxic and active in vivo[1].
LV-320 (0-120 µM; SKBR3, MCF7, JIMT1, and MDA-MB-231 cells) treatment results in a dose-dependent increase in endogenous LC3B-II and protein p62 levels in all four cell lines[1].LV-320 (120 µM; 48 hours; MDA-MB-231 cells) treatment results in an increase in LC3B-II, indicating that LV-320 blocks autophagic flux[1].
LV-320 (100-200 mg/kg; oral gavage; three times over two days; GFP-LC3 mice) treatment results in a terminal blood level of 169 µM and a liver level of 104 µM. The expression of GFP-LC3 puncta is significantly greater accumulation in LV-320 treated animals compared to controls. LC3B-II protein is also increased in LV-320-treated animals. The treatment do not cause significant toxicity in mice at either dose[1].
[1]. Bosc D, et al. A new quinoline-based chemical probe inhibits the autophagy-related cysteine protease ATG4B. Sci Rep. 2018 Aug 3;8(1):11653. doi: 10.1038/s41598-018-29900-x.