bs-181 and Neoplasms

Cyclin-dependent kinase (CDK) 7 has a unique functional repertoire by virtue of its dual role in transcription and cell cycle progression. Whereas CDK7 is ubiquitously expressed in various types of cancer, its downregulation leads to reduced cell proliferation. Importantly, it is now agreed that targeting transcription selectively limits the synthesis of mRNAs involved in tumor growth without causing an outage of transcription of housekeeping genes. Thus, CDK7 has been considered as a viable therapeutic target in cancer. Indeed, the development of CDK7 inhibitors has gained huge momentum with two molecules, CT7001 and SY-1365, currently under clinical development. Herein, we discuss the latest understanding of the role of CDK7 in cancer cells and provide an overview of the pharmacophores of CDK7 inhibitors, their efficacy in various cancer models, and their clinical development.

Topics: Animals; Antineoplastic Agents; Apoptosis; Cell Cycle Checkpoints; Cell Line, Tumor; Cell Proliferation; Cyclin-Dependent Kinase-Activating Kinase; Cyclin-Dependent Kinases; Humans; Neoplasms; Protein Kinase Inhibitors

A series of 5-substituted 3-isopropyl-7-[4-(2-pyridyl)benzyl]amino-1(2)H-pyrazolo[4,3-d]pyrimidine derivatives was synthesized and evaluated for their cyclin-dependent kinase (CDK) inhibition activity. The most potent compounds contained various hydroxyalkylamines at the 5 position and possessed low nanomolar IC50 values for CDK2 and CDK5. Preliminary profiling of one of the most active compounds on a panel of 50 protein kinases revealed its high selectivity for CDKs. The compounds arrested cells in S and G2/M phases, and induced apoptosis in various cancer cell lines. Significant dephosphorylation of the C-terminus of RNA polymerase II and focal adhesion kinase (FAK), well-established substrates of CDKs, has been found in treated cells. Cleavage of PARP-1, down-regulation of Mcl-1 and activation of caspases correlated well with CDK inhibition and confirmed apoptosis as the primary type of cell death induced in cancer cells treated with the compounds in vitro. A comparison of known purine-based CDK inhibitor CR8 with its pyrazolo[4,3-d]pyrimidine bioisosteres confirmed that the novel compounds are more potent in cellular assays than purines. Therefore, pyrazolo[4,3-d]pyrimidine may emerge as a novel scaffold in medicinal chemistry and as a source of potent CDK inhibitors.

Topics: Antineoplastic Agents; Apoptosis; Cell Cycle; Cell Line, Tumor; Cell Proliferation; Cyclin-Dependent Kinases; G2 Phase; Humans; Neoplasms; Protein Kinase Inhibitors; Pyrazoles; Pyrimidines

Cyclin-dependent kinase 7 (CDK7) activates cell cycle CDKs and is a member of the general transcription factor TFIIH. Although there is substantial evidence for an active role of CDK7 in mRNA synthesis and associated processes, the degree of its influence on global and gene-specific transcription in mammalian species is unclear. In the current study, we utilize two novel inhibitors with high specificity for CDK7 to demonstrate a restricted but robust impact of CDK7 on gene transcription in vivo and in in vitro-reconstituted reactions. We distinguish between relative low- and high-dose responses and relate them to distinct molecular mechanisms and altered physiological responses. Low inhibitor doses cause rapid clearance of paused RNA polymerase II (RNAPII) molecules and sufficed to cause genome-wide alterations in gene expression, delays in cell cycle progression at both the G1/S and G2/M checkpoints, and diminished survival of human tumor cells. Higher doses and prolonged inhibition led to strong reductions in RNAPII carboxyl-terminal domain (CTD) phosphorylation, eventual activation of the p53 program, and increased cell death. Together, our data reason for a quantitative contribution of CDK7 to mRNA synthesis, which is critical for cellular homeostasis.

Topics: Apoptosis; Cell Cycle; Cell Line, Tumor; Cyclin-Dependent Kinase-Activating Kinase; Cyclin-Dependent Kinases; Dose-Response Relationship, Drug; Gene Expression Regulation, Neoplastic; HEK293 Cells; HeLa Cells; Humans; Neoplasms; Phosphorylation; Protein Kinase Inhibitors; Purines; Pyrazoles; Pyrimidines; RNA Polymerase II; RNA, Messenger; Roscovitine; Triazines