Folic acid: a potential inhibitor against SARS-CoV-2 nucleocapsid protein.

CONTEXT: Coronavirus disease 2019 is a global pandemic. Studies suggest that folic acid has antiviral effects. Molecular docking shown that folic acid can act on SARS-CoV-2 Nucleocapsid Phosphoprotein (SARS-CoV-2 N). OBJECTIVE: To identify novel molecular therapeutic targets for SARS-CoV-2. MATERIALS AND METHODS: Traditional Chinese medicine targets and virus-related genes were identified with network pharmacology and big data analysis. Folic acid was singled out by molecular docking, and its potential target SARS-CoV-2 N was identified. Inhibition of SARS-CoV-2 N of folic acid was verified at the cellular level. RESULTS: In total, 8355 drug targets were potentially involved in the inhibition of SARS-CoV-2. 113 hub genes were screened by further association analysis between targets and virus-related genes. The hub genes related compounds were analysed and folic acid was screened as a potential new drug. Moreover, molecular docking showed folic acid could target on SARS-CoV-2 N which inhibits host RNA interference (RNAi). Therefore, this study was based on RNAi to verify whether folic acid antagonises SARS-CoV-2 N. Cell-based experiments shown that RNAi decreased mCherry expression by 81.7% (p < 0.001). This effect was decreased by 8.0% in the presence of SARS-CoV-2 N, indicating that SARS-CoV-2 N inhibits RNAi. With increasing of folic acid concentration, mCherry expression decreased, indicating that folic acid antagonises the regulatory effect of SARS-CoV-2 N on host RNAi. DISCUSSION AND CONCLUSIONS: Folic acid may be an antagonist of SARS-CoV-2 N, but its effect on viruses unclear. In future, the mechanisms of action of folic acid against SARS-CoV-2 N should be studied.

[SiRNA inhibition of E6AP expression in cervical cancer cells].

OBJECTIVE: To study the effect of RNA interference (RNAi) targeting E6AP on the proliferation and apoptosis of HeLa cells. METHODS: HeLa cells were cultured and divided into 3 groups: blank control group, cells transfected with nonsense siRNA (small interference RNA), and cells transfected with specific E6AP siRNA. The expressions of E6AP mRNA and protein were detected by RT-PCR and Western blot before and after the transfection respectively. Cell proliferation was determined by methylthiazolyl tetrazolium (MTT). The cell apoptosis index was assessed by flow cytometry. RESULTS: Upon treatment with E6AP siRNA for 24, 48 and 72 h, the expression level of E6AP mRNA decreased 33%, 72% and 70% than siRNA treated group. The protein expression levels in 48 h and 72 h E6AP siRNA groups decreased 38%, 59% comparing with those of the nonsense siRNA treated group (P < 0.05). The proliferative capacity of cells transfectd with E6AP siRNA was significantly lower than blank control group (F = 101.38, P < 0.05) and siRNA treated group (F = 38.64, P < 0.05). The apoptosis index of HeLa cells treated with E6AP siRNA was significantly higher than that of the nonsense siRNA (F = 41.48, P < 0.05) and the blank control group (F = 86.36, P < 0.05). CONCLUSION: SiRNA targeting can effectively suppress the expression levels of E6AP mRNA, corresponding with a proliferation inhibition and an enhanced apoptosis of HeLa cells.