dinaciclib and Lymphoma

Cyclin-dependent kinases are therapeutic targets frequently deregulated in various cancers. By convenient alkylation of the 5-sulfanyl group, we synthesized 3-isopropyl-7-[4-(2-pyridyl)benzyl]amino-1(2) H-pyrazolo[4,3- d]pyrimidines with various substitutions at position 5 with potent antiproliferative activity in non-Hodgkin lymphoma cell lines. The most potent derivative 4.35 also displayed activities across more than 60 cancer cell lines. The kinase profiling confirmed high selectivity of 4.35 toward cyclin-dependent kinases (CDKs) 2, 5, and 9, and the cocrystal with CDK2/cyclin A2 revealed its binding in the active site. Cultured lymphoma cell lines treated with 4.35 showed dephosphorylation of CDK substrates, cleavage of PARP-1, downregulation of XIAP and MCL-1, and activation of caspases, which collectively confirmed ongoing apoptosis. Moreover, 4.35 demonstrated significant activity in various cell line xenograft and patient-derived xenograft mouse models in vivo both as a monotherapy and as a combination therapy with the BCL2-targeting venetoclax. These findings support further studies of combinatorial treatment based on CDK inhibitors.

Topics: Animals; Antineoplastic Agents; Apoptosis; Bridged Bicyclo Compounds, Heterocyclic; Cell Line, Tumor; Cell Proliferation; Cyclin-Dependent Kinases; Drug Synergism; Female; Humans; Lymphoma; Mice; Molecular Structure; Protein Kinase Inhibitors; Pyrazoles; Pyrimidines; Structure-Activity Relationship; Sulfonamides; Xenograft Model Antitumor Assays

This study aimed to identify and evaluate the mechanism by which apoptosis and cell cycle arrest were induced by dinaciclib in lymphoma Raji cells.. The colony formation assay was used to detect cell proliferation of Raji cells. Cell cycle arrest and cell apoptosis were determined by flow cytometry and TUNEL assays, respectively. Protein expression related to the Raji cell state was evaluated by Western blot. The Raji/Dinaciclib drug-resistant cell line was established, where the regulating functions of CDK1-involved pathway were verified. In addition, the effect of dinaciclib in vivo was examined in orthotopically implanted tumors in nude mice.. Cell apoptosis was induced, and DNA synthesis ability was decreased in a time-dependent manner in dinaciclib-treated lymphoma Raji cells. Furthermore, the cell cycle was found to be blocked in the G2/M Phase. Further study indicated that CDK1-involved pathway played a key regulatory role in this process. It was revealed by cell transfection that the expression of cell cycle proteins was downregulated after treatment with dinaciclib through a CDK1-involved pathway, which eventually led to apoptosis. Knockdown of CDK1 restored the sensitivity of the Raji/Dinaciclib cells to dinaciclib. Xenograft model of nude mice showed that dinaciclib treatment in vivo could effectively inhibit tumor growth, consistent with the experiment results mentioned before.. In this study, we clarified the mechanisms through which dinaciclib induces Raji cell apoptosis and blocks the cell cycle through a CDK1-involved pathway, which supported that dinaciclib had potential values in the treatment of lymphoma.

Topics: Animals; Antineoplastic Agents; Bridged Bicyclo Compounds, Heterocyclic; CDC2 Protein Kinase; Cell Cycle Checkpoints; Cell Line, Tumor; Cell Proliferation; Cell Survival; Cyclic N-Oxides; Down-Regulation; Drug Resistance, Neoplasm; Female; Humans; Indolizines; Lymphoma; Mice; Mice, Nude; Pyridinium Compounds; Signal Transduction; Xenograft Model Antitumor Assays