Discovery of novel indazole-acylsulfonamide hybrids as selective Mcl-1 inhibitors.

Overexpressing myeloid cell leukemia sequence 1 (Mcl-1) protein is an important way to confer the resistance of cancer cells to conventional anti-cancer treatments. Therefore, developing Mcl-1 inhibitors has become an attractive strategy for cancer therapy. In the studies, a series of new indazole-acylsulfonamide hybrids were designed, synthesized and evaluated as potent Mcl-1 inhibitors. Among them, the most potent compound 17 (Ki = 0.43 µM) showed a little better inhibitory activity against Mcl-1 protein than positive control AT-101 (Ki = 0.45 µM). Pleasingly, it displayed > 40-fold selectivity over Bcl-2 (Ki = 18 µM) and Bcl-xL (no activity). Furthermore, compound 17 had good inhibitory activities against PC-3, MDA-MB-231 and K562 cells (IC50 = 12.3, 10.6 and 6.62 µM, respectively) and could effectively induce apoptosis and the activation of caspase-3 in a dose-dependent manner in K562 cells.

Small-molecule PROTACs: novel agents for cancer therapy.

Proteolysis-targeting chimera (PROTAC) is a new technology to selectively degrade target proteins via ubiquitin-proteasome system. PROTAC molecules (PROTACs) are a class of heterobifunctional molecules, which contain a ligand targeting the protein of interest, a ligand recruiting an E3 ligase and a linker connecting these two ligands. They provide several advantages over traditional inhibitors in potency, selectivity and drug resistance. Thus, many promising PROTACs have been developed in the recent two decades, especially small-molecule PROTACs. In this review, we briefly introduce the mechanism of PROTACs and focus on the progress of small-molecule PROTACs based on different E3 ligases. In addition, we also introduce the opportunities and challenges of small-molecule PROTACs for cancer therapy.

Indole: A privileged scaffold for the design of anti-cancer agents.

In general, heterocyclic compounds are a significant source of pharmacologically active compounds. Among them, the indole scaffold widely distributes in natural products and bioactive molecules including anti-cancer agents. In view of its unique physic-chemical and biological properties, it has been used as a privileged scaffold in the anti-cancer agents design. So far, many natural and synthetic indole derivatives have been discovered as promising anti-cancer agents used in clinic or clinical evaluations, suggesting its prominent place in anti-cancer drugs development. This review aimed to provide a clear knowledge on the recent development of indoles as anti-cancer agents, such as myeloid cell leukemia-1 (Mcl-1) inhibitors, proviral insertion site in moloney murine leukemia virus (Pim) inhibitors, histone deacetylase (HDAC) inhibitors, silent mating type information regulation 2 homolog (SIRT) inhibitors and tubulin inhibitors, and made an insight into the corresponding structure-activity relationships (SARs). We hope the review could give a guide to develop new anti-cancer agents with greater potency against drug-sensitive and drug-resistant cancers in the future.