Discovery of 2-(1H-indol-5-ylamino)-6-(2,4-difluorophenylsulfonyl)-8-methylpyrido[2,3-d]pyrimidin-7(8H)-one (7ao) as a potent selective inhibitor of Polo like kinase 2 (PLK2).

Several families of protein kinases have been shown to play a critical role in the regulation of cell cycle progression, particularly progression through mitosis. These kinase families include the Aurora kinases, the Mps1 gene product and the Polo Like family of protein kinases (PLKs). The PLK family consists of five members and of these, the role of PLK1 in human cancer is well documented. PLK2 (SNK), which is highly homologous to PLK1, has been shown to play a critical role in centriole duplication and is also believed to play a regulatory role in the survival pathway by physically stabilizing the TSC1/2 complex in tumor cells under hypoxic conditions. As a part of our research program, we have developed a library of novel ATP mimetic chemotypes that are cytotoxic against a panel of cancer cell lines. We show that one of these chemotypes, the 6-arylsulfonyl pyridopyrimidinones, induces apoptosis of human tumor cell lines in nanomolar concentrations. The most potent of these compounds, 7ao, was found to be a highly specific inhibitor of PLK2 when profiled against a panel of 288 wild type, 55 mutant and 12 lipid kinases. Here, we describe the synthesis, structure activity relationship, in vitro kinase specificity and biological activity of the lead compound, 7ao.

Biological evaluation of sulfone derivatives as anti-inflammatory and tumor cells growth inhibitory agents.

A variety of sulfone derivatives including three dimethyl arylsulfonyl malonates (1-3), two bis-(arylethenesulfonyl)-vinyl benzenes (4 and 5) and a sulfone triazole (6) were evaluated for their anti-inflammatory as well as tumor cells growth inhibitory activities in vitro. The sulfone derivatives 1, 2, 3 and 6 significantly and dose-dependently inhibited the production of inflammatory mediators such as nitric oxide (NO), and cytokines (tumor necrosis factor (TNF)-alpha and interleukin (IL)-12), in lipopolysaccharide (LPS) and interferon (IFN)-gamma activated murine peritoneal macrophages, without displaying cytotoxicity. The inhibitory mechanism is found through reducing iNOS protein expression. In addition, the derivatives 1-3 significantly arrest mitogen-stimulated spleen cells in G0/G1 stage, whereas compounds 4-6 blocked the same in the G2/M phase. Furthermore, the sulfone derivatives 3 and 6 showed dramatically reduction in the ratio of IFN-gamma to IL-4 production from mitogen-stimulated spleen cells. On the other hand, the novel compounds exhibited interesting cytotoxic activities against a panel of cell lines, particularly, 20 muM of compound 3 showed 50% cytotoxic effect on human hepatoma cell line, but has no effect on normal human peripheral blood mononuclear cells. In conclusion, compound 3 showed interesting anti-inflammatory and tumor cells growth inhibitory functions.