Strategies to overcome drug resistance using SHP2 inhibitors

Encoded by PTPN11, the SHP2 (Src homology-2 domain-containing protein tyrosine phosphatase-2) is widely recognized as a carcinogenic phosphatase. As a promising anti-cancer drug target, SHP2 regulates many signaling pathways such as RAS-RAF-ERK, PI3K-AKT and JAK-STAT. Meanwhile, SHP2 plays a significant role in regulating immune cell function in the tumor microenvironment. Heretofore, five SHP2 allosteric inhibitors have been recruited in clinical studies for the treatment of cancer. Most recently, studies have proved the therapeutic potential of SHP2 inhibitor in overcoming drug resistance of kinase inhibitors and programmed cell death-1 (PD-1) blockade. Herein, we review the structure, function and small molecular inhibitors of SHP2, and highlight recent progress in overcoming drug resistance using SHP2 inhibitor. We hope this review would facilitate the future clinical development of SHP2 inhibitors.

Recent advances in the development of allosteric protein tyrosine phosphatase inhibitors for drug discovery

Protein tyrosine phosphatases (PTPs) superfamily catalyzes tyrosine de-phosphorylation which affects a myriad of cellular processes. Imbalance in signal pathways mediated by PTPs has been associated with development of many human diseases including cancer, metabolic, and immunological diseases. Several compelling evidence suggest that many members of PTP family are novel therapeutic targets. However, the clinical development of conventional PTP-based active-site inhibitors originally was hampered by the poor selectivity and pharmacokinetic properties. In this regard, PTPs has been widely dismissed as "undruggable." Nonetheless, allosteric modulation has become increasingly an influential and alternative approach that can be exploited for drug development against PTPs. Unlike active-site inhibitors, allosteric inhibitors exhibit a remarkable target-selectivity, drug-likeness, potency, and in vivo activity. Intriguingly, there has been a high interest in novel allosteric PTPs inhibitors within the last years. In this review, we focus on the recent advances of allosteric inhibitors that have been explored in drug discovery and have shown an excellent result in the development of PTPs-based therapeutics. A special emphasis is placed on the structure-activity relationship and molecular mechanistic studies illustrating applications in chemical biology and medicinal chemistry.

Recent progress in development of cyclin-dependent kinase 7 inhibitors for cancer therapy

Introduction: Cyclin-dependent kinase 7 (CDK7) is a part of the CDK-activating kinase family (CAK) which has a key role in the cell cycle and transcriptional regulation. Several lines of evidence suggest that CDK7 is a promising therapeutic target for cancer. CDK7 selective inhibitors such as SY-5609 and CT7001 are in clinical development. Areas covered: We explore the biology of CDK7 and its role in cancer and follow this with an evaluation of the preclinical and clinical progress of CDK7 inhibitors, and their potential in the clinic. We searched PubMed and ClinicalTrials to identify relevant data from the database inception to 14 October 2020. Expert opinion: CDK7 inhibitors are next generation therapeutics for cancer. However, there are still challenges which include selectively, side effects, and drug resistance. Nevertheless, with ongoing clinical development of these inhibitors and greater analysis of their target, CDK7 inhibitors will become a promising approach for treatment of cancer in the near future.

Recent Advances in Small Molecule PROTACs for the Treatment of Cancer

The PROTAC (PROteolysis TArgeting Chimera) technology is a target protein degradation strategy, based on the ubiquitin-proteasome system, which has been gradually developed into a potential means of targeted cancer therapy in recent years. This strategy has already shown significant advantages over traditional small-molecule inhibitors in terms of pharmacodynamics, selectivity, and drug resistance. Several small molecule PROTACs have been in Phase I clinical trial. Herein, we have introduced the mechanism, characteristics, and advantages of PROTAC strategy. And we have summarized the recent advances in the development of small-molecule PROTACs for cancer treatment. We hope this review will be helpful in optimizing the design of the ideal small- molecule PROTACs and advancing targeted anticancer research.

HDAC-Bax Multiple Ligands Enhance Bax-Dependent Apoptosis in HeLa Cells

Inspired by the synergistic effect of BTSA1 (a Bax activator) and SAHA (a histone deacetylase (HDAC) inhibitor) in HeLa cell growth suppression, a series of novel HDAC-Bax multiple ligands were designed rationally. Compound 23, which possesses similar HDAC inhibitory activity relative to SAHA and Bax affinity comparable to BTSA1, exhibits a superior growth suppression against HeLa cells, and its antiproliferative activities are 15-fold and 3-fold higher than BTSA1 and SAHA, respectively. The better antiproliferative activity and lower cytotoxicity of compound 23 indicated that our HDAC-Bax multiple ligand design strategy achieved success. Further studies suggested that compound 23 could enhance Bax-dependent apoptosis by upregulating Bax, followed by inducing the conformational activation of Bax. To our knowledge, we first report HDAC-Bax multiple ligands and demonstrate a new paradigm for the treatment of solid tumors by enhancing Bax-dependent apoptosis.