ABSTRACT
The pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has severely affected human lives around the world as well as the global economy. Therefore, effective treatments against COVID-19 are urgently needed. Here, we screened a library containing Food and Drug Administration (FDA)-approved compounds to identify drugs that could target the SARS-CoV-2 main protease (Mpro), which is indispensable for viral protein maturation and regard as an important therapeutic target. We identified antimalarial drug tafenoquine (TFQ), which is approved for radical cure of Plasmodium vivax and malaria prophylaxis, as a top candidate to inhibit Mpro protease activity. The crystal structure of SARS-CoV-2 Mpro in complex with TFQ revealed that TFQ noncovalently bound to and reshaped the substrate-binding pocket of Mpro by altering the loop region (residues 139-144) near the catalytic Cys145, which could block the catalysis of its peptide substrates. We also found that TFQ inhibited human transmembrane protease serine 2 (TMPRSS2). Furthermore, one TFQ derivative, compound 7, showed a better therapeutic index than TFQ on TMPRSS2 and may therefore inhibit the infectibility of SARS-CoV-2, including that of several mutant variants. These results suggest new potential strategies to block infection of SARS-CoV-2 and rising variants.
Subject(s)
Aminoquinolines , Antiviral Agents , COVID-19 Drug Treatment , Coronavirus 3C Proteases , SARS-CoV-2 , Aminoquinolines/chemistry , Aminoquinolines/pharmacology , Antiviral Agents/chemistry , Antiviral Agents/pharmacology , Coronavirus 3C Proteases/antagonists & inhibitors , Humans , Molecular Docking Simulation , Pandemics , Protease Inhibitors/chemistry , Protease Inhibitors/pharmacology , SARS-CoV-2/drug effects , SARS-CoV-2/enzymology , Virus Internalization/drug effectsABSTRACT
Severe acute respiratory syndrome (SARS) led to a life-threatening form of atypical pneumonia in late 2002. Following that, Middle East Respiratory Syndrome (MERS-CoV) has recently emerged, killing about 36% of patients infected globally, mainly in Saudi Arabia and South Korea. Based on a scaffold we reported for inhibiting neuraminidase (NA), we synthesized the analogues and identified compounds with low micromolar inhibitory activity against 3CL(pro) of SARS-CoV and MERS-CoV. Docking studies show that a carboxylate present at either R(1) or R(4) destabilizes the oxyanion hole in the 3CL(pro). Interestingly, 3f, 3g and 3m could inhibit both NA and 3CL(pro) and serve as a starting point to develop broad-spectrum antiviral agents.
Subject(s)
Middle East Respiratory Syndrome Coronavirus , Peptide Hydrolases/metabolism , Protease Inhibitors/chemical synthesis , Protease Inhibitors/pharmacology , Severe acute respiratory syndrome-related coronavirus , Antiviral Agents/chemical synthesis , Antiviral Agents/chemistry , Antiviral Agents/pharmacology , Enzyme Activation/drug effects , Humans , Inhibitory Concentration 50 , Middle East Respiratory Syndrome Coronavirus/drug effects , Middle East Respiratory Syndrome Coronavirus/enzymology , Models, Molecular , Molecular Docking Simulation , Peptide Hydrolases/chemistry , Protease Inhibitors/chemistry , Severe acute respiratory syndrome-related coronavirus/drug effects , Severe acute respiratory syndrome-related coronavirus/enzymologyABSTRACT
Protein kinase C delta (PKCδ) is prominently expressed in the nuclei of EGFR-mutant lung cancer cells, and its presence correlates with poor survival of the patients undergoing EGFR inhibitor treatment. The inhibition of PKCδ has emerged as a viable approach to overcoming resistance to EGFR inhibitors. However, clinical-grade PKCδ inhibitors are not available, highlighting the urgent needs for the development of effective drugs that target PKCδ. In this study, we designed and synthesized a series of inhibitors based on the chemical structure of a pan PKC inhibitor sotrastaurin. This was achieved by incorporating a triazole ring group into the original sotrastaurin configuration. Our findings revealed that the sotrastaurin derivative CMU-0101 exhibited an elevated affinity for binding to the ATP-binding site of PKCδ and effectively suppressed nuclear PKCδ in resistant cells in comparison to sotrastaurin. Furthermore, we demonstrated that CMU-0101 synergistically enhanced EGFR TKI gefitinib sensitivity in resistant cells. Altogether, our study provides a promising strategy for designing and synthesizing PKCδ inhibitors with improved efficacy, and suggests CMU-0101 as a potential lead compound to inhibit PKCδ and overcome TKI resistance in lung cancers.
ABSTRACT
BACKGROUND: A growing body of evidence suggests that Hsp70, which is overexpressed in human breast tumors, plays a role in tumorigenesis and tumor progression in breast cancer as well as in its aggressive phenotypes. Hsp70 constitutes a potential therapeutic target in the treatment of this disease. METHODS: We developed a new series of rhodacyanine-based Hsp70 inhibitors, represented by compounds 1 and 6, in which the cationic pyridin-1-ium or thiazol-3-ium ring of existing Hsp70 inhibitors (e.g., JG-40 and JG-98) was replaced by a corresponding benzo- fused N-heterocycle. RESULTS: Several lines of evidence suggest that these benzo-fused derivatives may exert their antitumor activities, in part, by targeting Hsp70. These putative inhibitors displayed differential antiproliferative efficacy against breast cancer cells (IC50 as low as 0.25 µM) versus nontumorigenic MCF-10A breast epithelial cells (IC50 ≥ 5 µM). This was correlated with the corresponding Hsp70 expression levels. Using a protein refolding assay, we confirmed that these agents effectively inhibited the chaperone activity of Hsp70. Moreover, these inhibitors effectively suppressed the expression of well-known oncogenic client proteins of Hsp70's, including FoxM1, HuR, and Akt, which paralleled their antiproliferative efficacy. Supporting the established role of Hsp70 in regulating protein refolding, these derivatives induced autophagy, as manifested by the conversion of LC3B-I to LC3B-II. Notably, these putative Hsp70 inhibitors did not cause a compensatory elevation in Hsp90 expression, contrasting with the previously reported effects of Hsp90 inhibitors on Hsp70 upregulation. CONCLUSION: Together with the finding that compounds 1 and 6 showed improved microsomal stability, these results suggest the translational potential of these putative Hsp70 inhibitors to foster new strategies for cancer therapy. However, whether these benzo-fused rhodacyanines act on kinases or other targets remains unclear. It is currently under investigation.
Subject(s)
HSP70 Heat-Shock Proteins , Thiazoles , Cell Line, Tumor , HSP70 Heat-Shock Proteins/antagonists & inhibitors , HSP90 Heat-Shock Proteins , Humans , Pyridinium CompoundsABSTRACT
We have previously demonstrated the ability of I-Trp to disrupt the protein-protein interaction of ß-tubulin with chaperonin-containing TCP-1ß (CCT-ß). This caused more severe apoptosis in multidrug-resistant MES-SA/Dx5, compared to MES-SA, due to its higher CCT-ß overexpression. In this study, we screened a panel of cancer cell lines, finding CCT-ß overexpression in the triple-negative breast cancer cell line MDA-MB-231, colorectal cancer cell lines Colo205 and HCT116, and a gastric cancer cell line MKN-45. Thus, I-Trp killed these cancers with sub- to low-µM EC50, whereas it was non-toxic to MCF-10A. We then synthesized analogs of I-Trp and evaluated their cytotoxicity. Furthermore, apoptotic mechanism investigations revealed the activation of both protein ubiquitination/degradation and ER-associated protein degradation pathways. These pathways proceeded through activation of MAPKs at the onset of CCT-ß : ß-tubulin complex disruption. We thus establish an effective strategy to treat CCT-ß overexpressed cancers by disrupting the CCT-ß : ß-tubulin complex.
Subject(s)
Chaperonin Containing TCP-1/metabolism , Mitogen-Activated Protein Kinases/metabolism , Neoplasms/enzymology , Neoplasms/pathology , Tubulin/metabolism , Apoptosis/drug effects , Calcium/metabolism , Caspases/metabolism , Cell Line, Tumor , Endoplasmic Reticulum Stress/drug effects , Enzyme Activation/drug effects , Humans , Intracellular Space/metabolism , Ketones/pharmacology , Ketones/therapeutic use , Models, Biological , Neoplasms/drug therapy , Reproducibility of ResultsABSTRACT
Middle East respiratory syndrome coronavirus (MERS-CoV) causes severe acute respiratory illness with fever, cough and shortness of breath. Up to date, it has resulted in 1826 human infections, including 649 deaths. Analogous to picornavirus 3C protease (3Cpro), 3C-like protease (3CLpro) is critical for initiation of the MERS-CoV replication cycle and is thus regarded as a validated drug target. As presented here, our peptidomimetic inhibitors of enterovirus 3Cpro (6b, 6c and 6d) inhibited 3CLpro of MERS-CoV and severe acute respiratory syndrome coronavirus (SARS-CoV) with IC50 values ranging from 1.7 to 4.7 µM and from 0.2 to 0.7 µM, respectively. In MERS-CoV-infected cells, the inhibitors showed antiviral activity with EC50 values ranging from 0.6 to 1.4 µM, by downregulating the viral protein production in cells as well as reducing secretion of infectious viral particles into culture supernatants. They also suppressed other α- and ß-CoVs from human and feline origin. These compounds exhibited good selectivity index (over 70 against MERS-CoV) and could lead to the development of broad-spectrum antiviral drugs against emerging CoVs and picornaviruses.
Subject(s)
Antiviral Agents/pharmacology , Drug Discovery , Middle East Respiratory Syndrome Coronavirus/drug effects , Animals , Antiviral Agents/chemistry , Antiviral Agents/isolation & purification , Cats , Coronavirus/drug effects , Coronavirus Infections/virology , Humans , Peptidomimetics/chemistry , Peptidomimetics/pharmacology , Protease Inhibitors/pharmacology , Severe acute respiratory syndrome-related coronavirus/drug effects , Viral ProteinsABSTRACT
High-throughput screening was performed on â¼6800 compounds to identify KR-72039 as an inhibitor of H1N1 and H5N1 neuraminidases (NAs). Structure-activity relationship studies led to 3e, which inhibited H5N1 NA with an IC50 of 2.8 µM and blocked viral replication. Docking analysis shows that compounds bind to loop-430 around the NA active site. Compound 3l additionally inhibited H7N9 NA, making it a dual inhibitor of N1- and N2-type NAs.
Subject(s)
Neuraminidase/antagonists & inhibitors , Pyrazoles/chemical synthesis , Pyrazoles/pharmacology , Humans , Influenza A Virus, H1N1 Subtype/drug effects , Influenza A Virus, H5N1 Subtype/drug effects , Molecular Structure , Pyrazoles/chemistry , Structure-Activity RelationshipABSTRACT
INTRODUCTION: A novel coronavirus (CoV), unlike previous typical human coronaviruses (HCoVs), was identified as causative agent for severe acute respiratory syndrome (SARS). SARS first surfaced as a pandemic in late 2002 and originated in southern China. SARS-CoV rapidly spread to > 30 countries by 2003, infecting nearly 8,000 people and causing around 800 fatalities. After 10 years of silence, a 2012 report alarmed researchers about the emergence of a new strain of CoV causing SARS-like disease. AREAS COVERED: To combat SARS, scientists applied for patents on various therapeutic agents, including small-molecule inhibitors targeting the essential proteases, helicase and other proteins of the virus, natural products, approved drugs, molecules binding to the virus, neutralizing antibodies, vaccines, anti-sense RNA, siRNA and ribozyme against SARS-CoV. In this article, the patents published from 2008 to the present for the new therapeutics that could potentially be used in the prophylaxis and treatment of SARS are reviewed. EXPERT OPINION: The therapeutic interventions or prophylaxis discussed in this review seems to offer promising solutions to tackle SARS. Rather than being complacent about the results, we should envisage how to transform them into drug candidates that may be useful in combating SARS and related viral infections in the future.