Severe acute respiratory syndrome coronavirus-2 (SARS CoV-2) is the causative agent of the coronavirus disease-2019 (COVID-19) pandemic. Coronaviruses enter cells via fusion of the viral envelope with the plasma membrane and/or via fusion of the viral envelope with endosomal membranes after virion endocytosis. The spike (S) glycoprotein is a major determinant of virus infectivity. Herein, we show that the transient expression of the SARS CoV-2 S glycoprotein in Vero cells caused extensive cell fusion (formation of syncytia) in comparison to limited cell fusion caused by the SARS S glycoprotein. Both S glycoproteins were detected intracellularly and on transfected Vero cell surfaces. These results are in agreement with published pathology observations of extensive syncytia formation in lung tissues of patientswith COVID-19. These results suggest that SARS CoV-2 is able to spread from cellto-cell much more efficiently than SARS effectively avoiding extracellular neutralizing antibodies. A systematic screening of several drugs including cardiac glycosides and kinase inhibitors and inhibitors of human immunodeficiency virus (HIV) entry revealed that only the FDA-approved HIV protease inhibitor, nelfinavir mesylate (Viracept) drastically inhibited S-n-and S-o-mediated cell fusion with complete inhibition at a 10-μM concentration. In-silico docking experiments suggested the possibility that nelfinavir may bind inside the S trimer structure, proximal to the S2 amino terminus directly inhibiting S-n-and S-o-mediated membrane fusion. Also, it is possible that nelfinavir may act to inhibit S proteolytic processing within cells.These results warrant further investigations of the potential of nelfinavir mesylate to inhibit virus spread at early times after SARS CoV-2 symptoms appear.
A series of five boron dipyrromethene (BODIPY) bioconjugates containing an epidermal growth factor receptor (EGFR)-targeted pegylated LARLLT peptide and/or a glucose or biotin ethylene diamine group were synthesized, and the binding capability of the new conjugates to the extracellular domain of EGFR was investigated using molecular modeling, surface plasmon resonance, fluorescence microscopy, competitive binding assays, and animal studies. The BODIPY conjugates with a LARLLT peptide were found to bind specifically to EGFR, whereas those lacking the peptide bound weakly and nonspecifically. All BODIPY conjugates showed low cytotoxicity (IC50 > 94 μM) in HT-29 cells, both in the dark and upon light activation (1.5 J/cm2). Studies of nude mice bearing subcutaneous human HT-29 xenografts revealed that only BODIPY conjugates bearing the LARLLT peptide showed tumor localization 24 h after intravenous administration. The results of our studies demonstrate that BODIPY bioconjugates bearing the EGFR-targeting peptide 3PEG-LARLLT show promise as near-IR fluorescent imaging agents for colon cancers overexpressing EGFR.
Eighty-five percent of patients with lung cancer present with Non-small Cell Lung Cancer
(NSCLC). Targeted therapy approaches are promising treatments for lung cancer. However, despite the
development of targeted therapies using Tyrosine Kinase Inhibitors (TKI) as well as monoclonal antibodies,
the five-year relative survival rate for lung cancer patients is still only 18%, and patients inevitably
become resistant to therapy. Mutations in Kirsten Ras Sarcoma viral homolog (KRAS) and epidermal
growth factor receptor (EGFR) are the two most common genetic events in lung adenocarcinoma;
they account for 25% and 20% of cases, respectively. Anaplastic Lymphoma Kinase (ALK) is a transmembrane
receptor tyrosine kinase, and ALK rearrangements are responsible for 3-7% of NSCLC, predominantly
of the adenocarcinoma subtype, and occur in a mutually exclusive manner with KRAS and
EGFR mutations. Among drug-resistant NSCLC patients, nearly half exhibit the T790M mutation in
exon 20 of EGFR. This review focuses on some basic aspects of molecules involved in NSCLC, the development
of resistance to treatments in NSCLC, and advances in lung cancer therapy in the past ten
years. Some recent developments such as PD-1-PD-L1 checkpoint-based immunotherapy for NSCLC
are also covered.
AbstractCoronaviruses belong to a group of enveloped, positive-single stranded RNA viruses that are known to cause severe respiratory distress in animals and humans. The current SARS coronavirus-2 (SARS CoV-2) pandemic has caused more than 2,000,000 infections globally and nearly 200,000 deaths. Coronaviruses enter susceptible cells via fusion of the viral envelope with the plasma membrane and/or via fusion of the viral envelope with endosomal membranes after endocytosis of the virus into endosomes. Previous results with SARS and MERS CoV have shown that the Spike (S) glycoprotein is a major determinant of virus infectivity and immunogenicity. Herein, we show that expression of SARS CoV-2 S (S-n) glycoprotein after transient transfection of African green monkey kidney (Vero) cells caused extensive cell fusion in comparison to limited cell fusion caused by the SARS S (S-o) glycoprotein. S-n expression was detected intracellularly and on transfected Vero cell surfaces and caused the formation of very large multinucleated cells (syncytia) by 48 hours post transfection. These results are in agreement with published pathology observations of extensive syncytial formation in lung tissues of COVID-19 patients. This differential S-n versus S-o-mediated cell fusion suggests that SARS-CoV-2 is able to spread from cell-to-cell much more efficiently than SARS effectively avoiding extracellular spaces and neutralizing antibodies. A systematic screening of several drugs for ability to inhibit S-n and S-o cell fusion revealed that the FDA approved HIV-protease inhibitor, nelfinavir mesylate (Viracept) drastically inhibited S-n and S-o-mediated cell fusion in a dose-dependent manner. Complete inhibition of cell fusion was observed at a 10 micromolar concentration. Computational modeling and in silico docking experiments suggested the possibility that nelfinavir may bind inside the S trimer structure, proximal to the S2 amino terminus directly inhibiting S-n and S-o-mediated membrane fusion. Also, it is possible that nelfinavir mesylate acts on cellular processes to inhibit S proteolytic processing. These results warrant further investigations of the potential of nelfinavir mesylate as an antiviral drug, especially at early times after SARS-CoV-2 symptoms appear.
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