Simultaneous inhibition of Vps34 kinase would enhance PI3K? inhibitor cytotoxicity in the B-cell malignancies.

ABSTRACT: PI3K? has been found to be over-expressed in B-Cell-related malignancies. Despite the clinical success of the first selective PI3K? inhibitor, CAL-101, inhibition of PI3K? itself did not show too much cytotoxic efficacy against cancer cells. One possible reason is that PI3K? inhibition induced autophagy that protects the cells from death. Since class III PI3K isoform PIK3C3/Vps34 participates in autophagy initiation and progression, we predicted that a PI3K? and Vps34 dual inhibitor might improve the anti-proliferative activity observed for PI3K?-targeted inhibitors. We discovered a highly potent ATP-competitive PI3K?/Vps34 dual inhibitor, PI3KD/V-IN-01, which displayed 10-1500 fold selectivity over other PI3K isoforms and did not inhibit any other kinases in the kinome. In cells, PI3KD/V-IN-01 showed 30-300 fold selectivity between PI3K? and other class I PI3K isoforms. PI3KD/V-IN-01 exhibited better anti-proliferative activity against AML, CLL and Burkitt lymphoma cell lines than known selective PI3K? and Vps34 inhibitors. Interestingly, we observed FLT3-ITD AML cells are more sensitive to PI3KD/V-IN-01 than the FLT3 wt expressing cells. In AML cell inoculated xenograft mouse model, PI3KD/V-IN-01 exhibited dose-dependent anti-tumor growth efficacies. These results suggest that dual inhibition of PI3K? and Vps34 might be a useful approach to improve the PI3K? inhibitor's anti-tumor efficacy.

SUBMITTER: Liu X 

PROVIDER: S-EPMC5288202 | biostudies-literature | 2016 Aug

REPOSITORIES: biostudies-literature