Multicolor single cell imaging cytometry: A new drug screening platform for monitoring intracellular caspases as potential therapeutic targets

SH-03 is a rotenoid-containing deguelin analog. In this study, the anticancer activity and the dynamics of the caspase-mediated apoptotic cascade induced by SH-03 was simultaneously monitored in myeloid leukemia cells using multicolor single cell imaging cytometry as a new drug-screening platform. The constructed single cell imaging cytometer consists of an Ar-ion laser beam, a microscope objective lens, an acousto-optic tunable filter (AOTF), a charged coupled device (CCD) camera, and commercially available image processing software (MetaMorph). PI3K/AKT activation and phosphorylation assays were carried out to clarify the mechanistic details of the SH-03-induced intrinsic apoptotic pathway in HL-60 cells. SH-03 inhibited the PI3K/AKT signal transduction pathway in HL-60 cells. Given the fact that PI3K/AKT signaling pathway plays an important role in the proliferation, the inhibition of phosphorylation of PI3K/AKT by SH-03 can be assumed to trigger apoptosis. SH-03-induced caspase cascade was also investigated. Our results suggest that SH-03 induces apoptosis in HL-60 cells via a caspase-9-mediated intrinsic apoptotic pathway. Cellular imaging cytometry revealed that SH-03 triggers apoptosis via a caspase-mediated intrinsic pathway.