10,11-Dehydrocurvularin attenuates inflammation by suppressing NLRP3 inflammasome activation / 中国天然药物

10,11-Dehydrocurvularin (DCV) is a natural-product macrolide that has been shown to exert anti-inflammatory activity. However, the underlying mechanism of its anti-inflammatory activity remains poorly understood. Aberrant activation of the NLRP3 inflammasome is involved in diverse inflammation-related diseases, which should be controlled. The results showed that DCV specifically inhibited the activation of the NLRP3 inflammasome in association with reduced IL-1β secretion and caspase-1 activation, without effect on the NLRC4 and AIM2 inflammasomes. Furthermore, DCV disturbed the interaction between NEK7 and NLRP3, resulting in the inhibition of NLRP3 inflammasome activation. The C=C double bond of DCV was required for the NLRP3 inflammasome inhibition induced by DCV. Importantly, DCV ameliorated inflammation in vivo through inhibiting the NLRP3 inflammasome. Taken together, our study reveals a novel mechanism by which DCV suppresses inflammation, which indicates the potential role of DCV in NLRP3 inflammasome-driven inflammatory disorders.

Cardiotoxicity of Anti-PD-L1 Antibody and the Effect of Levothyroxine in Attenuating the Related Mortality in Mice / 中国肺癌杂志

BACKGROUND@#Immune checkpoint inhibitors (ICIs) such as antibodies against programmed cell death 1 (PD-1) and programmed cell death ligand 1 (PD-L1), have shown remarkable efficacies in many subtypes of cancers. However, ICIs may also cause severe immune-related adverse events in the recipient patients. Recently, ICI-associated myocarditis have been reported in hundreds of patients worldwide, with a mortality rate of approximately 50% in these cases. This study aims to recapitulate the cardiotoxicity and explore the detoxicifying approaches to attenuate mortality caused by PD-1/PD-L1 inhibitors in healthy mice.@*METHODS@#Six to eight-week-old C57BL/6 mice were inoculated with anti-PD-1 antibody (12.5 μg/g every 5 days for 6 injections), anti-PD-L1 antibody (10 μg/g once a week for 6 weeks), anti-PD-L1 antibody (with the same dosage described above) in combination with levothyroxine (0.25 μg/g, intraperitoneally injected half an hour before anti-PD-L1 antibody injection), or isotype control immunoglobulin IgG (10 μg/g once a week for 6 weeks). The ejection function of the hearts was detected by echocardiography, body temperature and blood pressure were detected by Mouse MonitorTM and non-invassive blood pressure minotor, and serum free thyroxine concentration was detected by The enzyme linked immunosorbent assay (ELISA).@*RESULTS@#PD-L1 was expressed at different levels by the cardiomyocytes of the mice. The isotype control immunoglobulin and anti-PD-1 antibody did not cause death of the mice. The 12 mice receiving 3-6 injections of anti-PD-L1 antibody showed a significant increase in the heart-to-tibial ratio and cardiomyoctye degeneration, hyalinization and extravascular inflammatory cell infiltration. In addition, the serum thyroxine was mardedly decreased to 1/3 of that in the control group mice, and the blood pressure and body temperature were abnormally decreased in mice upon treatment with PD-L1 blockade. Eight of the 12 (66.7%) mice died from multiple intravenous injection of anti-PD-L1 antibody.Intraperitoneal injection of levothyroxine 30 min before the injection of anti-PD-L1 antibody significantly attenuated the mortality rate of the anti-PD-L1 antibody-treated mice.@*CONCLUSIONS@#The anti-PD-L1 antibody is cardiotoxic and lethal, and levothyroxine is able to rescue the mice from this immune checkpoint inhibitor-caused mortality.

Degradation of SARS-CoV-2 receptor ACE2 by the E3 ubiquitin ligase Skp2 in lung epithelial cells / 医学前沿

An unexpected observation among the COVID-19 pandemic is that smokers constituted only 1.4%-18.5% of hospitalized adults, calling for an urgent investigation to determine the role of smoking in SARS-CoV-2 infection. Here, we show that cigarette smoke extract (CSE) and carcinogen benzo(a)pyrene (BaP) increase ACE2 mRNA but trigger ACE2 protein catabolism. BaP induces an aryl hydrocarbon receptor (AhR)-dependent upregulation of the ubiquitin E3 ligase Skp2 for ACE2 ubiquitination. ACE2 in lung tissues of non-smokers is higher than in smokers, consistent with the findings that tobacco carcinogens downregulate ACE2 in mice. Tobacco carcinogens inhibit SARS-CoV-2 spike protein pseudovirions infection of the cells. Given that tobacco smoke accounts for 8 million deaths including 2.1 million cancer deaths annually and Skp2 is an oncoprotein, tobacco use should not be recommended and cessation plan should be prepared for smokers in COVID-19 pandemic.

Identification of an E3 ligase-encoding gene RFWD3 in non-small cell lung cancer / 医学前沿

In order to unveil ubiquitin pathway genes (UPGs) that are essential for non-small cell lung cancer (NSCLC) cell proliferation, we recently conducted a siRNA screening experiment to knockdown the expression of 696 UPGs found in the human genome in A549 and H1975 NSCLC cells. We found that silencing of one of the candidates, RFWD3 that encodes an E3 ubiquitin ligase essential for the repair of DNA interstrand cross-links in response to DNA damage, led to dramatic inhibition of NSCLC cell proliferation with significant Z-scores. Knockdown of RFWD3 suppressed colony forming activity of NSCLC cells.We further evaluated the significance of RFWD3 in NSCLCs and found that this gene was more elevated in tumor samples than in paired normal lung tissues and was inversely associated with the clinical outcome of patients with NSCLC. Moreover, RFWD3 expression was significantly higher in smokers than in non-smokers. These results show for the first time that RFWD3 is required for NSCLC cell proliferation and may have an important role in lung carcinogenesis.

Advances in COVID-19: the virus, the pathogenesis, and evidence-based control and therapeutic strategies / 医学前沿

Since the outbreak of the COVID-19 pandemic in early December 2019, 81 174 confirmed cases and 3242 deaths have been reported in China as of March 19, 2020. The Chinese people and government have contributed huge efforts to combat this disease, resulting in significant improvement of the situation, with 58 new cases (34 were imported cases) and 11 new deaths reported on March 19, 2020. However, as of March 19, 2020, the COVID-19 pandemic continues to develop in 167 countries/territories outside of China, and 128 665 confirmed cases and 5536 deaths have been reported, with 16 498 new cases and 817 new deaths occurring in last 24 hours. Therefore, the world should work together to fight against this pandemic. Here, we review the recent advances in COVID-19, including the insights in the virus, the responses of the host cells, the cytokine release syndrome, and the therapeutic approaches to inhibit the virus and alleviate the cytokine storm. By sharing knowledge and deepening our understanding of the virus and the disease pathogenesis, we believe that the community can efficiently develop effective vaccines and drugs, and the mankind will eventually win this battle against this pandemic.

Genomic variations in the counterpart normal controls of lung squamous cell carcinomas / 医学前沿

Lung squamous cell carcinoma (LUSC) causes approximately 400 000 deaths each year worldwide. The occurrence of LUSC is attributed to exposure to cigarette smoke, which induces the development of numerous genomic abnormalities. However, few studies have investigated the genomic variations that occur only in normal tissues that have been similarly exposed to tobacco smoke as tumor tissues. In this study, we sequenced the whole genomes of three normal lung tissue samples and their paired adjacent squamous cell carcinomas.We then called genomic variations specific to the normal lung tissues through filtering the genomic sequence of the normal lung tissues against that of the paired tumors, the reference human genome, the dbSNP138 common germline variants, and the variations derived from sequencing artifacts. To expand these observations, the whole exome sequences of 478 counterpart normal controls (CNCs) and paired LUSCs of The Cancer Genome Atlas (TCGA) dataset were analyzed. Sixteen genomic variations were called in the three normal lung tissues. These variations were confirmed by Sanger capillary sequencing. A mean of 0.5661 exonic variations/Mb and 7.7887 altered genes per sample were identified in the CNC genome sequences of TCGA. In these CNCs, C:G→T:A transitions, which are the genomic signatures of tobacco carcinogen N-methyl-N-nitro-N-nitrosoguanidine, were the predominant nucleotide changes. Twenty five genes in CNCs had a variation rate that exceeded 2%, including ARSD (18.62%), MUC4 (8.79%), and RBMX (7.11%). CNC variations in CTAGE5 and USP17L7 were associated with the poor prognosis of patients with LUSC. Our results uncovered previously unreported genomic variations in CNCs, rather than LUSCs, that may be involved in the development of LUSC.

Carcinogens that induce the A:T > T:A nucleotide substitutions in the genome / 医学前沿

Recently, Ng et al. reported that the A:T > T:A substitutions, proposed to be a signature of aristolochic acid (AA) exposure, were detected in 76/98 (78%) of patients with hepatocellular carcinoma (HCC) from the Taiwan Province of China, and 47% to 1.7% of HCCs from the Chinese mainland and other countries harbored the nucleotide changes. However, other carcinogens, e.g., tobacco carcinogens 4-aminobiphenyl and 1,3-butadiene, air toxic vinyl chloride and its reactive metabolites chloroethylene oxide, melphalan and chlorambucil, also cause this signature in the genome. Since tobacco smoke is a worldwide public health threat and vinyl chloride distributes globally and is an air pollutant in Taiwan Province, the estimation of the patients' exposure history is the key to determine the "culprit" of the A:T > T:A mutations. Apparently, without estimation of the patients' exposure history, the conclusion of Ng et al. is unpersuasive and misleading.

Establishment of a GFP-based cellular model for screening novel proteasome inhibitors / 生物工程学报

To establish a green fluorescent protein (GFP)-based cellular model for screening proteasome inhibitors from compounds including extracts from Traditional Chinese Medicinal herbs, we transfected A549 cells with lentivirus expression vector pGC-E1-ZU1-GFP, and selected clones stably expressing ZU1-GFP. The A549-ZU1-GFP cells were treated with PS-341 for 24 h, and the accumulation of GFP was analyzed by fluorescence microscope. We found that the fluorescence intensity of A549-ZU1-GFP cells treated with PS-341 was significantly increased as compared to the control. We screened for proteasome inhibitors from compounds including some from Traditional Chinese Medicinal herbs, and the data suggested a few compounds could be novel proteasome inhibitors.

Rabdocoetsin B, a diterpenoid isolated from Isodon coetsa, is a potential proteasome inhibitor and induced apoptosis of t(8;21) leukemia cells / 生物工程学报

Effects of Rabdocoetsin B (Rabd-B), a diterpenoid extracted from Isodon coetsa, on t(8;21) leukemic cells was tested by CCK-8 assay and Flow cytometry. The A549 cells stably expressing pGC-E1-ZU1-GFP were treated with Rabd-B for 4 h, and the accumulation of GFP was detected by fluorescence microscope. Using Western blotting, we investigated the expression of Casp-3, PARP, S6', which is a subunit of the 19S regulatory complex of the 26S proteasome, and cellular ubiqutinated proteins. We found that Rabd-B induced growth inhibition and apoptosis of Kasumi-1 cells in a dose-dependent manner. In Kasumi-1 cells treated with 2.5 micromol/L Rabd-B for 24 h, pro-caspase-3 was processed into its active form. The substrate of Casp-3, poly ADP-ribose polymerase (PARP), was cleaved with generation of an 85 kD fragment. The increased GFP fluorescence intensity, cleavage of S6' and the accumulation of ubiquitinated proteins were found in Kasumi-1 cells treated with Rabd-B. These results suggested that Rabd-B is a potential proteasome inhibitor which induces programmed cell death of t(8;21) cells. Further study might provide evidence for employing Rabd-B in treating human t(8;21) leukemia.