Synthesis and Biological Evaluation of Pyrazolo[3,4-b]pyridin-4-ones as a New Class of Topoisomerase II Inhibitors

Synthesis and in vitro antiproliferative activity of certain novel pyrazolo[3,4-b]pyridines with potential p38α MAPK-inhibitory activity

Novel series of pyrazolo[3,4-b]pyridines 9a-j and 14a-f were prepared via a one-pot three-component reaction. Compounds 9a-j were synthesized by the reaction of 3-(4-chlorophenyl)-1-phenyl-1H-pyrazol-5-amine (4) with benzoyl acetonitriles 3a,b and aldehydes 5a-e, whereas the spiro derivatives 14a-f were synthesized by the reaction of pyrazole derivative 4 with 3a-c and indoline-2,3-diones 10a,b. Screening of the antiproliferative activity of 9a-j and 14a-f revealed that 14a and 14d were the most potent analogues against HepG2 and HeLa cells, with IC₅₀  = 4.2 and 5.9 μM, respectively. Moreover, compounds 9c and 14a could promote cell cycle disturbance and apoptosis in HepG2 cells, as evidenced by DNA flow cytometry and Annexin V-FITC/PI assays. Cell cycle analysis of 9c and 14a indicated a reduction in HepG2 cells in the G1 phase, with arrest in the S phase and the G2/M phase, respectively. Also, 9c and 14a are good apoptotic inducers in the HepG2 cell line. Furthermore, compounds 9h and 14d stood out as the most efficient antiproliferative agents in the NCI 60-cell line panel screening, with mean GI % equal to 60.3% and 55.4%, respectively. Additionally, 9c, 9h, 14a, and 14d showed good inhibitory action against the cellular pathway regulator p38α kinase, with IC₅₀  = 0.42, 0.41, 0.13, and 0.64 μM, respectively. A docking study was carried out on the p38α kinase active site, showing a binding mode comparable to that of reported p38 mitogen-activated protein kinase inhibitors. These newly discovered pyrazolo[3,4-b]pyridines could be considered as potential candidates for the development of newly targeted anticancer agents.

W436, a novel SMART derivative, exhibits anti-hepatocarcinoma activity by inducing apoptosis and G2/M cell cycle arrest in vitro and in vivo and induces protective autophagy

Hepatocellular carcinoma (HCC) is considered one of the most common primary liver cancers and the second leading cause of cancer-associated mortality around the world annually. Therefore, it is urgent to develop novel drugs for HCC therapy. We synthesized a novel 4-substituted-methoxybenzoyl-aryl-thiazole (SMART) analog, (5-(4-aminopiperidin-1-yl)-2-phenyl-2H-1,2,3-triazol-4-yl) (3,4,5-trimethoxyphenyl) methanone (W436), with higher solubility, stability, and antitumor activity than SMART against HCC cells in vivo. The purpose of this study was to investigate the mechanisms by which W436 inhibited cell growth in HCC cells. We observed that W436 inhibited the proliferation of HepG2 and Hep3B cells in a dose-dependent manner. Importantly, the anticancer activity of W436 against HCC cells was even higher than that of SMART in vivo. In addition, the antiproliferative effects of W436 on HCC cells were associated with G2/M cell cycle arrest and apoptosis via the activation of reactive oxygen species-mediated mitochondrial apoptotic pathway. W436 also induced protective autophagy by inhibiting the protein kinase B/mammalian target of rapamycin pathway. At the same time, W436 treatment inhibited the cell adhesion and invasion as well as the process of epithelial-to-mesenchymal transition Taken together, our results showed that W436 had the promising potential for the therapeutic treatment of HCC with improved solubility, stability, and bioavailability.