5-(2-carboxyethenyl) isatin derivative induces G2/M cell cycle arrest and apoptosis in human leukemia K562 cells.

Our previous study successfully identified that the novel isatin derivative (E)-methyl 3-(1-(4-methoxybenzyl)-2,3-dioxoindolin-5-yl) acrylate (HKL 2H) acts as an anticancer agent at an inhibitory concentration (IC50) level of 3nM. In this study, the molecular mechanism how HKL 2H induces cytotoxic activity in the human chronic myelogenous leukemia K562 cells was investigated. Flow cytometric analysis showed that the cells were arrested in the G2/M phase and accumulated subsequently in the sub-G1 phase in the presence of HKL 2H. HKL 2H treatment down-regulated the expressions of CDK1 and cyclin B but up-regulated the level of phosphorylated CDK1. Annexin-V staining and the classic DNA ladder studies showed that HKL 2H induced the apoptosis of K562 cells. Our study further showed that HKL 2H treatment caused the dissipation of mitochondrial membrane potential, activated caspase-3 and lowered the Bcl-2/Bax ratio in K562 cells, suggesting that the HKL 2H-causing programmed cell death of K562 cells was caused via the mitochondrial apoptotic pathway. Taken together, our data demonstrated that HKL 2H, a 5-(2-carboxyethenyl) isatin derivative, notably induces G2/M cell cycle arrest and mitochondrial-mediated apoptosis in K562 cells, indicating that this compound could be a promising anticancer candidate for further investigation.

Synthesis and anti-cancer activity evaluation of 5-(2-carboxyethenyl)-isatin derivatives.

A series of novel di- or trisubstituted isatin derivatives were designed and synthesized in 5-6 steps in 25-45% overall yields. Their structures were confirmed by 1H NMR and 13C NMR as well as LC-MS. The anticancer activity of the fourty-three new isatin derivatives against human T lymphocyte cells Jurkat was evaluated by MTT assay in vitro. SAR study suggested that the combination of 1-benzyl and 5-[trans-2-(methoxycarbonyl)ethen-1-yl] substitution greatly enhanced their cytotoxic activity. Among them, compound 2h was shown to have a significant cytotoxic activity with an IC50 value of 0.03 µM, more than 330-fold higher than that of it's mother molecule isatin. Investigation of the cell morphology changes and annexin-V/PI staining study demonstrated that compound 2h inhibited the proliferation of Jurkat cells by inducing apoptosis. Since compound 2h induced the dissipation of mitochondrial membrane potential and the activation of caspase-3, it was obvious that compound 2h inhibited the proliferation of Jurkat cells through the mitochondrial apoptotic pathway. Other than this, compound 2h exerted inhibition effect to many other tumor cells and only showed weak cytotoxic to human normal cells suggesting that compound 2h possessed a broad range of anticancer spectrum and high safety to normal cells.