Discovery of N,4-Di(1H-pyrazol-4-yl)pyrimidin-2-amine-Derived CDK2 Inhibitors as Potential Anticancer Agents: Design, Synthesis, and Evaluation.

Cyclin-dependent kinase 2 (CDK2) has been garnering considerable interest as a target to develop new cancer treatments and to ameliorate resistance to CDK4/6 inhibitors. However, a selective CDK2 inhibitor has yet to be clinically approved. With the desire to discover novel, potent, and selective CDK2 inhibitors, the phenylsulfonamide moiety of our previous lead compound 1 was bioisosterically replaced with pyrazole derivatives, affording a novel series of N,4-di(1H-pyrazol-4-yl)pyrimidin-2-amines that exhibited potent CDK2 inhibitory activity. Among them, 15 was the most potent CDK2 inhibitor (Ki = 0.005 µM) with a degree of selectivity over other CDKs tested. Meanwhile, this compound displayed sub-micromolar antiproliferative activity against a panel of 13 cancer cell lines (GI50 = 0.127-0.560 µM). Mechanistic studies in ovarian cancer cells revealed that 15 reduced the phosphorylation of retinoblastoma at Thr821, arrested cells at the S and G2/M phases, and induced apoptosis. These results accentuate the potential of the N,4-di(1H-pyrazol-4-yl)pyrimidin-2-amine scaffold to be developed into potent and selective CDK2 inhibitors for the treatment of cancer.

Discovery of Potent Inhibitors of Cyclin-Dependent Kinases 7 and 9: Design, Synthesis, Structure-Activity Relationship Analysis and Biological Evaluation.

Cyclin-dependent kinases (CDKs) 7 and 9 are deregulated in various types of human cancer and are thus viewed as therapeutic targets. Accordingly, small-molecule inhibitors of both CDKs are highly sought-after. Capitalising on our previous discovery of CDKI-73, a potent CDK9 inhibitor, medicinal chemistry optimisation was pursued. A number of N-pyridinylpyrimidin-2-amines were rationally designed, chemically synthesised and biologically assessed. Among them, N-(6-(4-cyclopentylpiperazin-1-yl)pyridin-3-yl)-4-(imidazo[1,2-a]pyrimidin-3-yl)pyrimidin-2-amine was found to be one of the most potent inhibitors of CDKs 7 and 9 as well as the most effective anti-proliferative agent towards multiple human cancer cell lines. The cellular mode of action of this compound was investigated in MV4-11 acute myeloid leukaemia cells, revealing that the compound dampened the kinase activity of cellular CDKs 7 and 9, arrested the cell cycle at sub-G1 phase and induced apoptosis.

Prodigiosin isolated from cell wall of Serratia marcescens alters expression of apoptosis-related genes and increases apoptosis in colorectal cancer cells.

Colorectal cancer remains often refractory to classic therapies. In consequence, the search for new anti-tumor agents with minimal toxicity is of particular interest in colon cancer treatment. Prodigiosin as a secondary metabolite of Serratia marcescens induces apoptosis in various kinds of cancer cells with low toxicity on normal cells. In the present study, we evaluated the effect of prodigiosin on proliferation and expression of apoptotic-related genes in HT-29 cells. Malignant cells were treated to various concentrations of prodigiosin and proliferation rate, survivin, Bcl-2, Bax and Bad mRNA levels, caspase 3 activation and apoptosis were evaluated by different cellular and molecular techniques. Treatment of cells with increasing concentration of prodigiosin decreased significantly cell proliferation in a dose- and time-dependent manner. Following 48-h treatment, growth rate was measured to be 77 ± 6.8, 41.3 ± 3.1 and 46 ± 6.3 % for 100, 400 and 600 nM prodigiosin, respectively, compared to untreated cells. This molecule induced 61.7, 90 and 89 % decrease in survivin mRNA level as well as 1.9-, 2.8- and 2.2-fold increase in caspase 3 activation for indicated concentrations of prodigiosin, respectively. The level of Bcl-2 mRNA was inversely proportional to Bax and Bad mRNA levels. Low mRNA levels of Bcl-2 combined with high levels of Bax and Bad mRNAs were correlated to higher apoptosis rate in treated cells. Our data suggest that prodigiosin-induced apoptosis may ascribe to Bcl-2 and survivin inhibition in HT-29 cells and these genes may provide promising molecular targets of prodigiosin. Collectively, prodigiosin may have a great potential for colorectal cancer-directed therapy.

In vivo toxicity of orally administrated silicon dioxide nanoparticles in healthy adult mice.

The increasing use of silica nanoparticles (SiNPs) in various applications including industrial, agriculture, and medicine has raised concerns about their potential risks to human health. Various nanotoxicity researches have been done on the assessment of SiNPs' toxic effects; however, a few in vivo investigations exist. In this investigation, an in vivo study was done in order to evaluate the oral toxicity of SiNPs. The biochemical levels of 19 different serum parameters were assessed. Moreover, the histopathological changes have been examined as well. We showed that SiNPs with diameters of 10-15 nm in size can cause significant changes in albumin, cholesterol, triglyceride, total protein, urea, HDL, and LDL as well as in alkaline phosphatase and aspartate aminotransferase activity. In addition, histopathological examinations demonstrated that SiNPs have toxic effects on various tissues including liver, kidney, lung, and testis.