CLEC5A and TLR2 are critical in SARS-CoV-2-induced NET formation and lung inflammation

Coronavirus-induced disease 19 (COVID-19) infects more than three hundred and sixty million patients worldwide, and people with severe symptoms frequently die of acute respiratory distress syndrome (ARDS). Autopsy demonstrates the presence of thrombosis and microangiopathy in the small vessels and capillaries. Recent studies indicated that excessive neutrophil extracellular traps (NETs) contributed to immunothrombosis, thereby leading to extensive intravascular coagulopathy and multiple organ dysfunction. Thus, understanding the mechanism of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-induced NET formation would be helpful to reduce thrombosis and prevent ARDS. It has been shown that sera from individuals with COVID-19 triggered NET release in vitro, and spleen tyrosine kinase (Syk) inhibitor R406 inhibited NETosis caused by COVID-19 plasma. However, the serum components responsible for NET formation are still unknown. In this study, we found that virus-free extracellular vesicles (EVs) from COVID-19 patients (COVID-19 EVs) induced robust NET formation via Syk-coupled C-type lectin member 5A (CLEC5A). Blockade of CLEC5A inhibited COVID-19 EVs-induced NETosis, and simultaneous blockade of CLEC5A and TLR2 further suppressed SARS-CoV-2-induced NETosis in vitro. Moreover, thromboinflammation and lung fibrosis were attenuated dramatically in clec5a-/-/tlr2-/- mice. These results suggest that COVID-19 EVs play critical roles in SARS-CoV-2-induced immunothrombosis, and blockade of CLEC5A and TLR2 is a promising strategy to inhibit SARS-CoV-2-induced intravascular coagulopathy and reduce the risk of ARDS in COVID-19 patients.

Retrieving the deleterious mutations before extinction: genome-wide comparison of shared derived mutations in liver cancer and normal population.

STUDY PURPOSE: Deleterious mutations would be rapidly purged from natural populations along with the extinction of their carriers. The currently observed mutations in existing species are mostly neutral. The inaccessibility of deleterious mutations impedes the functional studies on how these mutations affect the fitness at individual level. STUDY DESIGN: The connection between the deleterious genotype and the non-adaptive phenotype could be bridged by sequencing the genome before extinction. Although this approach is no longer feasible for evolutionary biologists, it is feasible for cancer biologists by profiling the mutations in tumour samples which are so deleterious that the carriers hardly live. RESULTS: By comparing the derived mutation profile between normal populations and patients with liver cancer, we found that the shared mutations, which are highly deleterious, are suppressed to low allele frequencies in normal populations and tissues, but show remarkably high frequency in tumours. The density of shared mutations is negatively correlated with gene conservation and expression levels. CONCLUSIONS: Deleterious mutations are suppressed in functionally important genes as well as in normal populations. This work deepened our understanding on how natural selection act on deleterious mutations by analogising the cancer evolution to species evolution, which are essentially the same molecular process but at different time scales.

Large-scale omics data reveal the cooperation of mutation-circRNA-miRNA-target gene network in liver cancer oncogenesis.

Aims: Clarifying the initial trigger of the differentially expressed genes in cancers helps researchers understand the cellular system as a whole network. Materials & methods: We retrieve the transcriptome and translatome of tumor and normal tissues from ten liver cancer patients and define differentially expressed genes and tumor-specific mutations. We associate the oncogenesis with the mutations by target prediction and experimental verification. Results: Upregulated genes have tumor-specific mutations in 3'UTRs that abolish the binding of miRNAs. For downregulated genes, their corresponding miRNAs are mutually targeted by two circRNAs, with mutations in base-pairing regions. Transfection experiments support the oncogenic role of these mutations. Conclusions: The tumor-specific mutations serve as the initial trigger of liver cancer. The mutation-circRNA-miRNA-target gene chain is completed.

Synonymous mutations that regulate translation speed might play a non-negligible role in liver cancer development.

BACKGROUND: Synonymous mutations do not change the protein sequences. Automatically, they have been regarded as neutral events and are ignored in the mutation-based cancer studies. However, synonymous mutations will change the codon optimality, resulting in altered translational velocity. METHODS: We fully utilized the transcriptome and translatome of liver cancer and normal tissue from ten patients. We profiled the mutation spectrum and examined the effect of synonymous mutations on translational velocity. RESULTS: Synonymous mutations that increase the codon optimality significantly enhanced the translational velocity, and were enriched in oncogenes. Meanwhile, synonymous mutations decreasing codon optimality slowed down translation, and were enriched in tumor suppressor genes. These synonymous mutations significantly contributed to the translational changes in tumor samples compared to normal samples. CONCLUSIONS: Synonymous mutations might play a role in liver cancer development by altering codon optimality and translational velocity. Synonymous mutations should no longer be ignored in the genome-wide studies.

Genome-wide expression changes mediated by A-to-I RNA editing correlate with hepatic oncogenesis.

BACKGROUND: Adenosine-to-inosine (A-to-I) RNA editing is one of the most prevalent RNA modifications in the animal kingdom. Since inosine is recognized as guanosines, the A-to-I process mimics A-to-G DNA mutations but can be controlled in a more flexible manner compared to DNA alterations. METHODS: We parsed the transcriptomes and translatomes of liver cancer and normal tissues from ten patients. We profiled the landscape of the A-to-I RNA editome in these samples and interrogated whether the A-to-I processes participated in the gene expression regulation in oncogenesis. RESULTS: Globally, editing activity was enhanced in all tumor samples compared to that in normal samples. Accordingly, expression of the gene encoding the RNA editing enzyme ADAR (adenosine deaminase acting on RNA) was elevated. Two intronic self-editing sites in ADAR mRNAs controlled its splicing pattern and may regulate its translation efficiency (TE). Moreover, the expression of oncogenes was generally upregulated in tumors, whereas tumor suppressor genes (TSG) were downregulated, possibly due to alterations to microRNA binding sites or RNA splicing defects caused by A-to-I editing. CONCLUSIONS: A-to-I RNA editing plays a crucial role in the oncogenesis of liver cancer. ADAR regulates its own expression via self-editing, and it also affects global transcriptomes and translatomes involving cancer-related genes by RNA editing and changing their expression patterns.

FoxM1 promotes epithelial-mesenchymal transition of hepatocellular carcinoma by targeting Snai1.

Forkhead box protein M1 (FoxM1) is aberrantly expressed in several types of human malignancy, and serves an important role in tumor metastasis. Epithelial­mesenchymal transition (EMT) of cancer cells has been associated cancer metastasis; however, the implication of FoxM1 in EMT and its putative roles in the regulation of cancer metastasis remain to be elucidated. In the present study, the expression of FoxM1, Snai1 and E­cadherin in hepatocellular carcinoma (HCC) cell lines with various metastatic potentials, and in normal liver cells, was investigated using western blot analysis and reverse transcription­quantitative polymerase chain reaction. The effects of FoxM1 on the invasive and migratory capabilities of HCC cells were evaluated using wound healing and Transwell migration assays. The present results demonstrated that FoxM1 expression was significantly upregulated in HCC cells compared with in normal hepatocytes (P<0.05). In addition, FoxM1 expression was significantly increased in MHCC­LM3 cells, characterized by higher metastatic potential, compared with in SMMC­7721 cells, which have a lower metastatic potential. Furthermore, overexpression of FoxM1 was demonstrated to be negatively correlated with E­cadherin (P<0.05) and positively associated with Snai1 (P<0.05) expression. These observations suggested that FoxM1 may enhance the invasion and migration of cancer cells, and thus promotes their EMT, in a mechanism that may involve the regulation of Snai1. Therefore, it may be hypothesized that FoxM1 has potential as a novel diagnostic marker and therapeutic target for the treatment of patients with HCC.

Lobaplatin combined floxuridine/pirarubicin-based transcatheter hepatic arterial chemoembolization for unresectable primary hepatocellular carcinoma.

PURPOSE: To assess the effect and safety of lobaplatin combinated floxuridine /pirarubicin in transcatheter hepatic arterial chemoembolization(TACE) of unresectable primary liver cancer. PATIENTS AND METHODS: TACE combined with the chemotherapy regimen was used to treat 34 unresectable primary liver cancer patients. DSA/ MRI/CT/blood routine examinations were used to evaluate short term activity and toxicity after 4-5 weeks, the process being repeated if necessary. RESULTS: Among the 34 cases, 1 (2.9%) showed a complete response, 21 (61.7%) a partial response, 8 (23.5%) stable disease, and 4 progressive disease, with a total effective rate of 67.6%. The content of alpha fetoprotein dropped by over 50% in 20 cases (58.8%). The rate of recovery was hepatalgia (88.2%), ascites (47.1%), appetite (55.9%), Performance Status(30.4%). The median follow-up time (MFT) was 281 days (63-558 days), and median progression-free survival was 118.5 days (95%, CI:88.8-148.2 days). Adverse reactions (III-IV grade) were not common, with only 4 cases of vomiting and 2 cases of thrombocytopenia (III grade). CONCLUSIONS: Lobaplatin-based TACE is an effective and safe treatment for primary liver cancer.