In vitro antitumor mechanism of a novel cyclin-dependent kinase inhibitor CDKI-83

Multipathway regulation induced by 4-(phenylsulfonyl)morpholine derivatives against triple-negative breast cancer

Phenotypic drug discovery (PDD) is an effective drug discovery approach by observation of therapeutic effects on disease phenotypes, especially in complex disease systems. Triple-negative breast cancer (TNBC) is composed of several complex disease features, including high tumor heterogeneity, high invasive and metastatic potential, and a lack of effective therapeutic targets. Therefore, identifying effective and novel agents through PDD is a current trend in TNBC drug development. In this study, 23 novel small molecules were synthesized using 4-(phenylsulfonyl)morpholine as a pharmacophore. Among these derivatives, GL24 (4m) exhibited the lowest half-maximal inhibitory concentration value (0.90 µM) in MDA-MB-231 cells. To investigate the tumor-suppressive mechanisms of GL24, transcriptomic analyses were used to detect the perturbation for gene expression upon GL24 treatment. Followed by gene ontology (GO) analysis, gene set enrichment analysis (GSEA), and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis, multiple ER stress-dependent tumor suppressive signals were identified, such as unfolded protein response (UPR), p53 pathway, G2/M checkpoint, and E2F targets. Most of the identified pathways triggered by GL24 eventually led to cell-cycle arrest and then to apoptosis. In summary, we developed a novel 4-(phenylsulfonyl)morpholine derivative GL24 with a strong potential for inhibiting TNBC cell growth through ER stress-dependent tumor suppressive signals.

Cyclin-dependent kinases in cancer: Role, regulation, and therapeutic targeting

Regulated cell division is one of the fundamental phenomena which is the basis of all life on earth. Even a single base pair mutation in DNA leads to the production of the dysregulated protein that can have catastrophic consequences. Cell division is tightly controlled and orchestrated by proteins called cyclins and cyclin-dependent kinase (CDKs), which serve as licensing factors during different phases of cell division. Dysregulated cell division is one of the most important hallmarks of cancer and is commonly associated with a mutation in cyclins and CDKs along with tumor suppressor proteins. Therefore, targeting the component of the cell cycle which leads to these characteristics would be an effective strategy for treating cancers. Specifically, Cyclin-dependent kinases (CDKs) involved in cell cycle regulation have been identified to be overexpressed in many cancers. Many studies indicate that oncogenesis occurs in cancerous cells by the overactivity of different CDKs, which impact cell cycle progression and checkpoint dysregulation which is responsible for development of tumor. The development of CDK inhibitors has emerged as a promising and novel approach for cancer treatment in both solid and hematological malignancies. Some of the novel CDK inhibitors have shown remarkable results in clinical trials, such as-Ribociclib®, Palbociclib® and Abemaciclib®, which are CDK4/6 inhibitors and have received FDA approval for the treatment of breast cancer. In this chapter, we discuss the molecular mechanism through which cyclins and CDKs regulate cell cycle progression and the emergence of cyclins and CDKs as rational targets in cancer. We also discuss recent advances in developing CDK inhibitors, which have emerged as a novel class of inhibitors, and their associated toxicities in recent years.

Discovery of a potent, highly selective, and orally bioavailable inhibitor of CDK8 through a structure-based optimisation

CDK8 is deregulated in multiple types of human cancer and is viewed as a therapeutic target for the treatment of the disease. Accordingly, the search for small-molecule inhibitors of CDK8 is being intensified. Capitalising on our initial discovery of AU1-100, a potent CDK8 inhibitor yet with a limited degree of kinase selectivity, a structure-based optimisation was carried out, with a series of new multi-substituted pyridines rationally designed, chemically prepared and biologically evaluated. Such endeavour has culminated in the identification of 42, a more potent CDK8 inhibitor with superior kinomic selectivity and oral bioavailability. The mechanism underlying the anti-proliferative effect of 42 on MV4-11 cells was studied, revealing that the compound arrested the G1 cell cycle and triggered apoptosis. The low risk of hepato- and cardio-toxicity of 42 was estimated. These findings merit further investigation of 42 as a targeted cancer therapeutic.

Hepatocellular Carcinoma: Etiology and Current and Future Drugs

Hepatocellular carcinoma (HCC) is swiftly increasing in prevalence globally with a high mortality rate. The progression of HCC in patients is induced with advanced fibrosis, mainly cirrhosis, and hepatitis. The absence of proper preventive or curative treatment methods encouraged extensive research against HCC to develop new therapeutic strategies. The Food and Drug Administration-approved Nexavar (sorafenib) is used in the treatment of patients with unresectable HCC. In 2017, Stivarga (regorafenib) and Opdivo (nivolumab) got approved for patients with HCC after being treated with sorafenib, and in 2018, Lenvima (lenvatinib) got approved for patients with unresectable HCC. But, owing to the rapid drug resistance development and toxicities, these treatment options are not completely satisfactory. Therefore, there is an urgent need for new systemic combination therapies that target different signaling mechanisms, thereby decreasing the prospect of cancer cells developing resistance to treatment. In this review, HCC etiology and new therapeutic strategies that include currently approved drugs and other potential candidates of HCC such as Milciclib, palbociclib, galunisertib, ipafricept, and ramucirumab are evaluated.

Targeting Cyclin-Dependent Kinases in Ovarian Cancer

Ovarian cancer is the most common gynecological malignancy in the United States, and prognosis is generally poor because the disease is often diagnosed at an advanced stage. Cyclin-dependent kinases (CDKs) are a family of serine/threonine kinases whose activity is regulated by CDK inhibitors (CKIs) and cyclins. Generally, cyclins and CKIs promote and inhibit CDK activation, respectively. Since cancer commonly involves dysregulation of cell cycle, cyclins and CDKs have been targeted in a variety of tumors using small molecules, peptides, immunotherapy, and CKIs. In this review we discuss the significance of cell cycle dysregulation in ovarian cancer as well as recent advances targeting CDKs in ovarian cancer and potential future directions. Although many of the studies assessing CDK-targeting therapies in ovarian cancer are at an early preclinical stage, there is significant evidence that targeting CDKs, particularly in combination with traditional platinum-based drugs, could have significant efficacy in ovarian cancer. Nevertheless, before these agents can be investigated in humans, additional preclinical development is needed, including using in vivo tumor models and additional studies into their mechanism of action.