Discovery of (2-(4-Substituted phenyl)quinolin-4-yl)(4-isopropylpiperazin-1-yl)methanone Derivatives as Potent Proprotein Convertase Subtilisin/Kexin Type 9 Inhibitors.

Inhibition of proprotein convertase subtilisin/kexin type 9 (PCSK9) plays an increasingly important role in the treatment of hyperlipidemia. In pursuit of potent small molecules that block the PCSK9/low-density lipoprotein receptor (LDLR) protein-protein interaction (PPI), a series of 2-phenylquinoline-4-carboxylic acid derivatives were designed and synthesized based on previously derived molecules. In the in vitro PPI inhibition test, compounds M1, M12, M14, M18 and M27 exhibited potent activities with IC50 values of 6.25 µM, 0.91 µM, 2.81 µM, 4.26 µM and 0.76 µM, respectively, compared with SBC-115337 (IC50 value of 9.24 µM). Molecular docking and molecular dynamics simulations revealed the importance of hydrophobic interactions in the binding of inhibitors to the PPI interface of PCSK9. In LDLR expression and LDL uptake assays, the tested compounds M1, M12 and M14 were found to restore LDLR expression levels and to increase the extracellular LDL uptake capacity of HepG2 cells in the presence of exogenous PCSK9. Collectively, novel small-molecule PCSK9/LDLR PPI inhibitors (especially M12) with in vitro lipid lowering ability, were discovered as lead compounds for further development of hypolipidemic drugs.

Discovery of [5,5'-bibenzo[d][1,3]dioxol]-6-substituted amine derivatives as potent proprotein convertase subtilisin/kexin type 9 inhibitors.

Proprotein convertase subtilisin/kexin type 9 (PCSK9) has emerged as a promising therapeutic target for the treatment of hyperlipidemia. In discovery of novel small molecules that interfere PCSK9/LDLR protein-protein interaction (PPI), structural modification was performed based on our previously derived compounds. A series of [5,5'-bibenzo[d][1,3]dioxol]-6-amine analogs were designed and synthesized for the activity evaluation. In the PCSK9/LDLR PPI impairing test, molecules D28 and D29, exhibited remarkable inhibitory potency with IC50 values of 8.30 and 6.70 µM compared with SBC-115337 (17.89 µM), respectively. Molecular docking predicted the binding pattern of compounds D28 and D29 in the LDLR binding site of PCSK9. Hydrophobic interactions play an important role in the binding of aromatic molecular fragments to the pockets in the PCSK9/LDLR binding interface. Further LDLR expression and LDL uptake studies revealed that both D28 and D29 restored LDLR expression on the surface of hepatic HepG2 cells and improved extracellular LDL uptake in the presence of PCSK9. It is significant that molecules D28 and D29 exhibited potential for the treatment of hyperlipidemia in current in vitro investigations. Generally, lead compounds with novel structures were developed in the present study for further design of lipid-lowering molecules by targeting PCSK9/LDLR PPI.

Targeting feedback activation of signaling transduction pathways to overcome drug resistance in cancer.

Dysregulation or aberrant signaling transduction contributes to tumorigenesis. Targeting these abnormal signaling pathways becomes an effective anticancer strategy. However, feedback activation or crosstalk between signaling pathways drives adaptive drug resistance which causes failure of cancer therapy. In this review article, we summarized treatments that cause feedback activation of AKT, ERK, STAT3, EGFR, FGFR, and HER2/3 signaling pathways and the combination therapy to enhance anti-tumor effect or to overcome drug resistance, to explore the underlying mechanisms that define the protein molecules participated or regulated the feedback activation. In addition, we reviewed clinical trials that employ combination treatments to suppress feedback activation and improve therapeutic efficacy of cancer treatments.

BC-02 eradicates liver cancer stem cells by upregulating the ROS-dependent DNA damage.

Cancer stem cells (CSCs) are responsible for chemoresistance, tumor recurrence and metastasis. Reportedly, aminopeptidase N (APN, also known as CD13) is a marker for semi-quiescent CSCs and a therapeutic target in human liver CSCs. In the present study, the effect of BC-02, a compound obtained by conjugating a CD13 inhibitor bestatin and fluorouracil (5-FU), was investigated toward liver CSCs. Tumor spheres formed in serum-free culture conditions have been successfully used to enrich CSCs. In this study, the sphere cells were shown to have several characteristics of CSCs, including drug resistance, high tumorigenicity, epithelial-mesenchymal transition (EMT) phenotype, lower reactive oxygen species (ROS) levels, greater colony-forming efficiency and increased proliferation capacity in vitro. Furthermore, BC-02 effectively suppressed self-renewal and malignant proliferation of CSCs compared with 5-FU, bestatin, and even the combination of 5-FU and bestatin. In addition, cell proliferation was effectively suppressed when exposed to 5-FU plus CD13-neutralizing antibody (CD13 Ab) compared with 5-FU alone. BC-02 can effectively inhibit the activity of CD13. Results demonstrated that CD13 inhibitor BC-02 impaired the properties of liver CSCs by targeting CD13 and upregulating the intracellular ROS and ROS-induced DNA damage. BC-02 might be a potential therapeutic agent for eradicating the liver CSCs and overcoming chemoresistance in liver cancer.