In vitro activity: LY333531 strikingly decreases the chance of HUVEC survival and the effect of LY333531 on apoptotic cell death in HUVEC significantly increases compared with the AGEs group. Blockade of PKC-beta up-regulates the expression of Bax and Bad proteins and down-regulates the expression of Bcl-2 protein. Moreover, LY333531 reduces the ratio of Bcl-2/Bax. LY333531 can further prompt AGEs-induced endothelial cells apoptosis. The increased expression of Bax, Bad and decreased expression of Bcl-2 and Bcl-2/Bax ratio are associated with the apoptotic process.

Kinase Assay: Ruboxistaurin hydrochloride is a selective and ATP-competitive PKCβ inhibitor, with IC50s of 4.7 and 5.9 nM for PKCβI and PKCβII, shows less potent inhibition on PKCη (IC50, 52 nM), PKCα (IC50, 360 nM), PKCγ (IC50, 300 nM), PKCδ (IC50, 250 nM), and has no effect on PKCζ (IC50,>100 μM).

Cell Assay: HUVECs are seeded into 96-well plates in low glucose DMEM with 10% FBS for 12 h. Afterwards, HUVECs are starved for 12 h and incubated with BSA (200 μg/ml), AGEs (200 μg/ml) and LY333531 (200 nM)+AGEs (200 μg/ml) for 48 h. Then, the medium is replaced with 0.5 mg/ml MTT and at 37 oC in a 95% air/5% CO2 incubator for 4 h. Finally, the medium containing MTT is aspirated and replaced by dimethyl sulphoxide (DMSO). OD is measured with a Microplate spectrophotometer. AGEs:advanced glycation end products.