Broad ultra-potent neutralization of SARS-CoV-2 variants by monoclonal antibodies specific to the tip of RBD

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants of concern (VOCs) continue to wreak havoc across the globe. Higher transmissibility and immunologic resistance of VOCs bring unprecedented challenges to epidemic extinguishment. Here we describe a monoclonal antibody, 2G1, that neutralizes all current VOCs and has surprising tolerance to mutations adjacent to or within its interaction epitope. Cryo-electron microscopy structure showed that 2G1 bound to the tip of receptor binding domain (RBD) of spike protein with small contact interface but strong hydrophobic effect, which resulted in nanomolar to sub-nanomolar affinities to spike proteins. The epitope of 2G1 on RBD partially overlaps with ACE2 interface, which gives 2G1 ability to block interaction between RBD and ACE2. The narrow binding epitope but high affinity bestow outstanding therapeutic efficacy upon 2G1 that neutralized VOCs with sub-nanomolar IC50 in vitro. In SARS-CoV-2 and Beta- and Delta-variant-challenged transgenic mice and rhesus macaque models, 2G1 protected animals from clinical illness and eliminated viral burden, without serious impact to animal safety. Mutagenesis experiments suggest that 2G1 could be potentially capable of dealing with emerging SARS-CoV-2 variants in future. This report characterized the therapeutic antibodies specific to the tip of spike against SARS-CoV-2 variants and highlights the potential clinical applications as well as for developing vaccine and cocktail therapy.

Natural product toosendanin reverses the resistance of human breast cancer cells to adriamycin as a novel PI3K inhibitor.

Adriamycin (ADM) is a commonly used drug in clinical breast cancer treatment. However, some breast cancer types or breast cancers subjected to repeated ADM exposure develop strong resistance to ADM thus limiting its clinical efficacy. In this study, we found for the first time that toosendanin (TSN), a triterpenoid extracted from the traditional Chinese medicine Melia toosendan Sieb et Zucc, could successfully reverse adriamycin resistance in human breast cancer cells. Immunofluorescence and HPLC analysis demonstrated that TSN promoted adriamycin accumulation in breast cancer cells, especially in the nucleus. Furthermore, TSN could significantly reduce ABCB1 expression. We then found that TSN was capable of suppressing adriamycin-induced Akt phosphorylation, probably due to downregulation of the PI3K catalytic subunits P110α and P110ß, and inhibition of DNA-PKcs. Importantly, the inhibitory effect of TSN on PI3K P110α and P110ß expression was specifically observed in breast cancer cells but not in normal human cells. Moreover, TSN significantly potentiated the anti-cancer effect of ADM in the 4T1 breast cancer model and its inhibition rate was nearly 90%. Thus, TSN could be used as a novel PI3K inhibitor to reverse breast cancer resistance. The combination of ADM and TSN may represent a useful strategy for human breast cancer therapy.

Effects of quinolinic acid on autophagy and protein expressions of related signaling pathway in PC12 cells / 中国药理学与毒理学杂志

OBJECTIVE To investigate whether quinolinic acid(QA)induces autophagy in PC12 cells and its relationship with glycogen synthase kinase-3β(GSK-3β)/β-catenin related signaling path?ways. METHODS PC12 cells were treated with QA 2.5,5.0 and 10.0 mmol·L-1 for 24 h. The cell viability was determined by MTT assay. Autophagy fluorescent spots labelled form of microtubule-associated protein 1 light chain 3(LC3)was examined by LC3 immunostaining. The expressions of GSK-3β,β-catenin,LC3 and Beclin 1 were determined by Western blotting. RESULTS QA inhibited PC12 cell survival in a concentration-dependent manner,and IC50 was 8.7 mmol · L- 1. Compared with normal control group,QA 2.5,5.0 and 10.0 mmol · L-1 increased autophagic intracellular LC3 fluorescence spots,elevated the expression ratio of LC3-Ⅱ/LC3-Ⅰ and expression of Beclin 1 in PC12 cells(P<0.05). In addition,QA enhanced GSK-3βexpression and decreasedβ-catenin expression(P<0.05,P<0.01). CONCLUSION QA induces autophagy in PC12 cells. This mechanism may be associated with the activation of GSK-3β/β-catenin related signaling pathways.

Expression changes of HIF-1α, ROCK-2, FoxM1 in the lead acetate-induced injury in PC12 cells / 中国药理学通报

Aim To investigate the expression and im-plication of HIF-1α, ROCK-2 , FoxM1 in PC12 cell in-jury induced by lead acetate. Methods PC12 cells were treated with lead acetate at the doses of 100 , 200 and 400 μmol·L-1 . The cell viability was determined by MTT reduction assay and LDH assay, the intracellu-lar production of oxygen species was measured by as-sessing SOD and MDA levels, cell apoptosis was deter-mined by Hoechst 33342 staining, the expressions of HIF-1α, ROCK-2 , FoxM1 , Bcl-2 and Bax were deter-mined by immunoblotting analysis. Results Lead ac-etate induced cell injury in PC12 cells in a dose-de-pendent manner, and it potentiated oxygen radical pro-duction and cell apoptosis. In addition, lead acetate enhanced HIF-1α and ROCK-2 expressions, increased Bax/Bcl-2 ratio and decreased FoxM1 expression. Conclusion Lead acetate can induce PC12 cell apop-tosis, which may be related with the expressions of HIF-1α, ROCK-2 and FoxM1 . Cellular oxidative stress may contribute to the injury as well.

Role of HIF-1αin quinolinic acid-induced injury in PC12 cells / 中国药理学通报

Aim To investigate the role of HIF-1 αin PC1 2 cell injury induced by quinolinic acid.Methods PC1 2 cells were treated with quinolinic acid at the do-ses of 2.5,5 and 1 0 mmol·L -1 ,the cell viability was determined by MTT reduction assay and LDH as-say,the intracellular levels of oxygen species was measured by assessing SOD and MDA levels,cell ap-optosis was determined by Hoechst 33258 staining,the intracellular distribution of HIF-1 αwas examined by HIF-1 αimmunostaining,and the expressions of HIF-1 α,Akt,p-Akt,Bcl-2 and Bax were determined by im-munoblotting analysis.Results Quinolinic acid in-duced cell injury in PC1 2 cells in a dose-dependent manner,and potentiated oxygen radical production and cell apoptosis.In addition,quinolinic acid enhanced HIF-1 αexpression and accumulation in nuclei.The p-Akt expression and Bax/Bcl-2 ratio was increased by quinolinc acid in PC1 2 cells.Conclusions HIF-1 αand Akt mediate qunolinc acid-induced cell apoptosis in PC1 2 cells.And cellular oxidative stress may con-tribute to the injury as well.