Discovery of novel and bioavailable histone deacetylases and cyclin-dependent kinases dual inhibitor to impair the stemness of leukemia cells

Combination therapy and dual-target inhibitors based on cyclin-dependent kinases (CDKs): Emerging strategies for cancer therapy

Cyclin-dependent kinases (CDKs) are pivotal regulators of the cell cycle and transcriptional machinery, making them attractive targets for cancer therapy. While CDK inhibitors have demonstrated promising clinical outcomes, they also face challenges in enhancing efficacy, particularly in overcoming drug resistance. Combination therapies have emerged as a key strategy to augment the effectiveness of CDK inhibitors when used alongside other kinase inhibitors or non-kinase-targeted agents. Dual-target inhibitors that simultaneously inhibit CDKs and other oncogenic drivers are gaining attention, offering novel avenues to optimize cancer therapy. Based on the structural characterization and biological functions of CDKs, this review comprehensively examines the structure-activity relationship (SAR) of existing dual-target CDK inhibitors from a drug design perspective. We also thoroughly investigate the preclinical studies and clinical translational potential of combination therapies and dual-target inhibitors. Tailoring CDK inhibitors to specific cancer subtypes and therapeutic settings will inspire innovative approaches for the next generation of CDK-related therapies, ultimately improving patient survival.

Synthesis, Antiproliferative Activity, and Molecular Simulation Study of Novel Nootkatone Derivatives Containing Pyrazole-amide Moiety

To explore new types of anticancer drugs, a series of novel nootkatone-derived pyrazole-amide compounds were synthesized by the multi-step reaction using natural product nootkatone as starting material. The structures of the synthesized compounds were confirmed by Fourier-transform infrared, proton nuclear magnetic resonance (1H NMR), carbon-13 NMR, and high-resolution mass spectrometry. In vitro antiproliferative activity of the target compounds against human hepatocellular carcinoma cells (SMMC-7721, Huh7, and HepG2) and human breast cancer cell lines (MCF-7) has been assessed by the Cell Counting Kit-8 method. It was found that compounds 4i, 4q, 4r, and 4t exhibited good antiproliferative activity against all the tested cancer cells, in which compound 4r had the best activity with half-maximal inhibitory concentration values of 26.19, 1.51, 10.63, and 10.43 µM against SMMC-7721, HepG2, Huh7, and MCF-7 cell lines, respectively. Meanwhile, the three-dimensional quantitative structure-activity relationship model with predictive ability was established by the Comparative Molecular Field Analysis method to investigate the relationship between substituents on the target compounds and antiproliferative activity. Furthermore, the possible interaction mode of compound 4r with Survivin protein was probed by molecular docking, and found that compound 4r shared similar binding patterns with that of Survivin protein inhibitors YM155 and NSC80467. The work can bring new inspiration to the exploration of new types of anticancer drugs.

Design, synthesis, and antiproliferative activity evaluation of novel α-mangostin derivatives by ROS/MAPK signaling pathway

Novel hydroxamic acid and 3,6-amide modified α-mangostin derivatives were synthesized and evaluated their antiproliferative activities against KYSE 30 (esophageal cancer), HCT 116 (colon cancer), and HGC 27 (gastric cancer) cell lines. Most of the new derivatives displayed stronger anti-proliferative activities compared to α-mangostin. Among all the derivatives, compound 4a exhibited the most potent activity, with IC50 values of 0.57 ± 0.29 μM, 3.27 ± 0.16 μM, and 2.28 ± 1.02 μM against KYSE 30, HCT 116, and HGC 27 cells, respectively. Subsequent mechanism studies revealed that compound 4a inhibited cancer cells proliferation and colonies formation in a concentration-dependent manner. Additionally, compound 4a caused cell cycle arrest in a p53 dependent manner and induced apoptosis in p53 independent way. Meanwhile, 4a suppressed cell cycle related proteins (Cyclin D1 and cyclin B1) expression, increased pro-apoptotic proteins (cleaved PARP, cleaved caspase-7, and cleaved caspase-9) and decreased anti-apoptotic proteins (Bcl-2) expression. Moreover, 4a increased reactive oxygen species (ROS) levels in KYSE 30 cells and upregulated the expression of proteins related to the ROS related MAPK signaling pathway (p-ERK, p-p38, and p-JNK). These findings suggest that compound 4a holds promising potential as an antiproliferative agent by targeting MAPK signaling pathway to inhibit cell cycle progress, induce apoptosis and produce ROS in cancers.

Novel dual inhibitor targeting CDC25 and HDAC for treating triple-negative breast cancer

Triple-negative breast cancer (TNBC) presents a significant challenge for treatment due to its aggressive nature and the lack of effective therapies. This study developed dual inhibitors against cell division cycle 25 (CDC25) and histone deacetylases (HDACs) for TNBC treatment. CDC25 phosphatases are crucial for activating cyclin-dependent kinases (CDKs), the master regulators of cell cycle progression. HDACs regulate various biological processes by deacetylating histone and non-histone proteins, affecting gene expression, chromatin structure, cell differentiation, and proliferation. Dysregulations of HDAC and CDC25 are associated with several human malignancies. We generated a group of dual inhibitors for CDC25 and HDAC by combining the molecular structures of CDC25 (quinoline-5,8-dione) and HDAC (hydroxamic acid or benzamide) pharmacophores. The newly developed compounds were evaluated against various solid-tumor, leukemia, and non-malignant breast epithelial cells. Among the synthesized compounds, 18A emerged as a potent inhibitor, demonstrating significant cytotoxicity against TNBC cells, superior to its effects on other cancer types while sparing non-malignant cells. 18A possessed similar HDAC inhibitory activity as MS-275 and potently suppressed CDC25 activity in vitro and the CDK1 dephosphorylation in cells. Additionally, 18A hindered the progression of S and G2/M phases, triggered DNA damage, and induced apoptosis. These findings underscore the potential of 18A as a targeted therapy for TNBC and warrants further preclinical development.

Recent Discovery and Development of Inhibitors that Target CDK9 and Their Therapeutic Indications

CDK9 is a cyclin-dependent kinase that plays pivotal roles in multiple cellular functions including gene transcription, cell cycle regulation, DNA damage repair, and cellular differentiation. Targeting CDK9 is considered an attractive strategy for antitumor therapy, especially for leukemia and lymphoma. Several potent small molecule inhibitors, exemplified by TG02 (4), have progressed to clinical trials. However, many of them face challenges such as low clinical efficacy and multiple adverse reactions and may necessitate the exploration of novel strategies to lead to success in the clinic. In this perspective, we present a comprehensive overview of the structural characteristics, biological functions, and preclinical status of CDK9 inhibitors. Our focus extends to various types of inhibitors, including pan-inhibitors, selective inhibitors, dual-target inhibitors, degraders, PPI inhibitors, and natural products. The discussion encompasses chemical structures, structure-activity relationships (SARs), biological activities, selectivity, and therapeutic potential, providing detailed insight into the diverse landscape of CDK9 inhibitors.

A review of progress in o-aminobenzamide-based HDAC inhibitors with dual targeting capabilities for cancer therapy

Histone deacetylases, as a new class of anticancer targets, could maintain homeostasis by catalyzing histone deacetylation and play important roles in regulating the expression of target genes. Due to the fact that simultaneous intervention with dual tumor related targets could improve treatment effects, researches on innovative design of dual-target drugs are underway. HDAC is known as a "sensitizer" for the synergistic effects with other anticancer-target drugs because of its flexible structure design. The synergistic effects of HDAC inhibitor and other target inhibitors usually show enhanced inhibitory effects on tumor cells, and also provide new strategies to overcome multidrug resistance. Many research groups have reported that simultaneously inhibiting HDAC and other targets, such as tubulin, EGFR, could enhance the therapeutic effects. The o-aminobenzamide group is often used as a ZBG group in the design of HDAC inhibitors with potent antitumor effects. Given the prolonged inhibitory effects and reduced toxic side effects of HDAC inhibitors using o-aminobenzamide as the ZBG group, the o-aminobenzamide group is expected to become a more promising alternative to hydroxamic acid. In fact, o-aminobenzamide-based dual inhibitors of HDAC with different chemical structures have been extensively prepared and reported with synergistic and enhanced anti-tumor effects. In this work, we first time reviewed the rational design, molecular docking, inhibitory activities and potential application of o-aminobenzamide-based HDAC inhibitors with dual targeting capabilities in cancer therapy, which might provide a reference for developing new and more effective anticancer drugs.