LincRNA01703 Facilitates CD81+ Exosome Secretion to Inhibit Lung Adenocarcinoma Metastasis via the Rab27a/SYTL1/CD81 Complex.

Metastasis, a major cause of cancer-related mortality worldwide, frequently occurs early in the diagnosis of lung adenocarcinoma (LUAD). However, the precise molecular mechanisms governing the aggressive metastatic behavior of LUAD remain incompletely understood. In this study, we present compelling evidence indicating that the long noncoding RNA linc01703 is significantly downregulated in metastatic lung cancer cells. Intriguingly, in vivo experiments revealed that Linc01703 exerted a profound inhibitory effect on lung cancer metastasis without discernible impact on the in vitro proliferation or invasion capacities of LUAD cells. Mechanistically, Linc01703 enhanced the interaction between Rab27a, SYTL1, and CD81, consequently promoting the secretion of CD81+ exosomes. These exosomes, in turn, suppressed the infiltration of immune cells within the tumor microenvironment, thereby impeding LUAD metastasis. Importantly, our analysis of lung cancer tissues revealed a correlation between reduced CD81 expression and an unfavorable patient prognosis. Collectively, our findings suggest that Linc01703 functions as a metastasis suppressor by facilitating the secretion of CD81+ exosomes through the formation of the Rab27a/SYTL1/CD81 complex.

Epidemiology, genetic characteristics, and association with meteorological factors of human metapneumovirus infection in children in southern China: A 10-year retrospective study.

OBJECTIVES: This study aimed to determine the epidemiological and genetic features of human metapneumovirus (HMPV) infection in children in southern China, and the effect of meteorological factors on infection. METHODS: 14,817 children (≤14 years) with acute respiratory tract infections from 2010 to 2019 were examined for HMPV and other respiratory viruses by real-time quantitative polymerase chain reaction. Full-length F gene of 54 positive samples were sequenced and subjected to phylogenetic analysis. The correlation between the HMPV-positive rate and meteorological factors was analyzed by linear regression analysis. RESULTS: HMPV was detected in 524 (3.5%) children, who were mostly younger than 1 year. The seasonal peak of HMPV prevalence mainly occurred in spring. Respiratory syncytial virus was the most common virus coinfected with HMPV (5.3%). Phylogenetic analysis revealed that the sequenced HMPV strains belonged to four sublineages, including A2b (1.9%), A2c (31.5%), B1 (50.0%), and B2 (16.7%). After adjusting for all meteorological factors, sunshine duration was inversely correlated with the HMPV-positive rate. CONCLUSION: HMPV is an important respiratory pathogen that causes acute respiratory tract infections in children in southern China, particularly in children ≤5 years old. The prevalence peak of HMPV in this area appeared in spring, and the predominant subtype was B1. Meteorological factors, especially long sunshine duration, might decrease the HMPV prevalence.

m6 A-Dependent Modulation via IGF2BP3/MCM5/Notch Axis Promotes Partial EMT and LUAD Metastasis.

The importance of mRNA N6-methyladenosine (m6 A) modification during tumor metastasis is controversial as it plays distinct roles in different biological contexts. Moreover, how cancer cell plasticity is shaped by m6 A modification is interesting but remains uncharacterized. Here, this work shows that m6 A reader insulin like growth factor 2 mRNA binding protein 3 (IGF2BP3) is remarkably upregulated in metastatic lung adenocarcinoma (LUAD) and indicates worse prognosis of patients. Interestingly, IGF2BP3 induces partial epithelial-mesenchymal-transition (EMT) and confers LUAD cells plasticity to metastasize through m6 A-dependent overactivation of Notch signaling. Mechanistically, IGF2BP3 recognized m6 A-modified minichromosome maintenance complex component (MCM5) mRNAs to prolong stability of them, subsequently upregulating MCM5 protein, which competitively inhibits SIRT1-mediated deacetylation of Notch1 intracellular domain (NICD1), stabilizes NICD1 protein and contributes to m6 A-dependent IGF2BP3-mediated cellular plasticity. Notably, a tight correlation of the IGF2BP3/MCM5/Notch axis is evidenced in clinical LUAD specimens. Therefore, this study elucidates a critical role of m6 A modification on LUAD cell plasticity in fostering tumor metastasis via the above axis, providing potential targets for metastatic LUAD.

PHF14 enhances DNA methylation of SMAD7 gene to promote TGF-ß-driven lung adenocarcinoma metastasis.

Aberrant activation of TGF-ß signaling plays a pivotal role in cancer metastasis and progression. However, molecular mechanisms underlying the dysregulation of TGF-ß pathway remain to be understood. Here, we found that SMAD7, a direct downstream transcriptional target and also a key antagonist of TGF-ß signaling, is transcriptionally suppressed in lung adenocarcinoma (LAD) due to DNA hypermethylation. We further identified that PHF14 binds DNMT3B and serves as a DNA CpG motif reader, recruiting DNMT3B to the SMAD7 gene locus, resulting in DNA methylation and transcriptional suppression of SMAD7. Our in vitro and in vivo experiments showed that PHF14 promotes metastasis through binding DNMT3B to suppress SMAD7 expression. Moreover, our data revealed that PHF14 expression correlates with lowered SMAD7 level and shorter survival of LAD patients, and importantly that SMAD7 methylation level of circulating tumor DNA (ctDNA) can potentially be used for prognosis prediction. Together, our present study illustrates a new epigenetic mechanism, mediated by PHF14 and DNMT3B, in the regulation of SMAD7 transcription and TGF-ß-driven LAD metastasis, and suggests potential opportunities for LAD prognosis.

ATOH8 binds SMAD3 to induce cellular senescence and prevent Ras-driven malignant transformation.

The process of oncogene-induced senescence (OIS) and the conversion between OIS and malignant transformation during carcinogenesis is poorly understood. Here, we show that following overactivation of oncogene Ras in lung epithelial cells, high-level transforming growth factor ß1 (TGF-ß1)-activated SMAD3, but not SMAD2 or SMAD4, plays a determinant role in inducing cellular senescence independent of the p53/p16/p15 senescence pathways. Importantly, SMAD3 binds a potential tumor suppressor ATOH8 to form a transcriptional complex that directly represses a series of cell cycle-promoting genes and consequently causes senescence in lung epithelial cells. Interestingly, the prosenescent SMAD3 converts to being oncogenic and essentially facilitates oncogenic Ras-driven malignant transformation. Furthermore, depleting Atoh8 rapidly accelerates oncogenic Ras-driven lung tumorigenesis, and lung cancers driven by mutant Ras and Atoh8 loss, but not by mutant Ras only, are sensitive to treatment of a specific SMAD3 inhibitor. Moreover, hypermethylation of the ATOH8 gene can be found in approximately 12% of clinical lung cancer cases. Together, our findings demonstrate not only epithelial cellular senescence directed by a potential tumor suppressor-controlled transcriptional program but also an important interplay between the prosenescent and transforming effects of TGF-ß/SMAD3, potentially laying a foundation for developing early detection and anticancer strategies.

Cytoplasmic Clusterin Suppresses Lung Cancer Metastasis by Inhibiting the ROCK1-ERK Axis.

Clusterin (CLU) is a heterodimeric glycoprotein that has been detected in diverse human tissues and implicated in many cellular processes. Accumulating evidence indicates that the expression of secreted CLU correlates with the progression of cancers. However, the molecular mechanisms underlying its tumor-suppressive roles are incompletely uncovered. In this study, we demonstrate that precursor CLU is widely downregulated in lung cancer tissue, in which secretory CLU proteins are slightly decreased. Impressively, overexpressing CLU potently inhibits the migration, invasion and metastasis of lung cancer cells, whereas silencing CLU promotes this behavior; however, it appears that secretory CLU fails to exert similar anti-metastatic effects. Interestingly, the cytoplasmic precursor CLU binds ROCK1 to abrogate the interaction between ROCK1 and ERK and impair ERK activity, leading to the suppression of lung cancer invasiveness. Meanwhile, the expression of CLU was remarkably diminished in lung cancer bone metastasis loci when compared with subcutaneous tumors in the mouse model and hardly detected in the bone metastasis loci of lung cancer patients when compared with the primary. These findings reveal a novel insight into the function and regulation of cytoplasmic CLU in lung cancer, which might be a potential target for the diagnosis and treatment of metastatic lung cancer.

Loss of ATF4 leads to functional aging-like attrition of adult hematopoietic stem cells.

Aging of hematopoietic stem cells (HSCs) directly contributes to dysfunction of hematopoietic and immune systems due to aging-associated alterations in HSC features. How the function of adult HSCs is regulated during aging so that relevant pathologic abnormalities may occur, however, remains incompletely understood. Here, we report that ATF4 deficiency provokes severe HSC defects with multifaceted aging-like phenotype via cell-autonomous mechanisms. ATF4 deletion caused expansion of phenotypical HSCs with functional attrition, characterized by defective repopulating and self-renewal capacities and myeloid bias. Moreover, the ATF4−/− HSC defects were associated with elevated mitochondrial ROS production by targeting HIF1α. In addition, loss of ATF4 significantly delayed leukemogenesis in the MLL-AF9­induced leukemia model. Mechanistically, ATF4 deficiency impaired HSC function with aging-like phenotype and alleviated leukemogenesis by regulating HIF1α and p16Ink4a. Together, our findings suggest a possibility of developing new strategies for the prevention and management of HSC aging and related pathological conditions.

An RFC4/Notch1 signaling feedback loop promotes NSCLC metastasis and stemness.

Notch signaling represents a key mechanism mediating cancer metastasis and stemness. To understand how Notch signaling is overactivated to couple tumor metastasis and self-renewal in NSCLC cells, we performed the current study and showed that RFC4, a DNA replication factor amplified in more than 40% of NSCLC tissues, directly binds to the Notch1 intracellular domain (NICD1) to competitively abrogate CDK8/FBXW7-mediated degradation of NICD1. Moreover, RFC4 is a functional transcriptional target gene of Notch1 signaling, forming a positive feedback loop between high RFC4 and NICD1 levels and sustained overactivation of Notch signaling, which not only leads to NSCLC tumorigenicity and metastasis but also confers NSCLC cell resistance to treatment with the clinically tested drug DAPT against NICD1 synthesis. Furthermore, together with our study, analysis of two public datasets involving more than 1500 NSCLC patients showed that RFC4 gene amplification, and high RFC4 and NICD1 levels were tightly correlated with NSCLC metastasis, progression and poor patient prognosis. Therefore, our study characterizes the pivotal roles of the positive feedback loop between RFC4 and NICD1 in coupling NSCLC metastasis and stemness properties and suggests its therapeutic and diagnostic/prognostic potential for NSCLC therapy.

Long non-coding RNA LEISA promotes progression of lung adenocarcinoma via enhancing interaction between STAT3 and IL-6 promoter.

Long non-coding RNAs (lncRNAs) are emerging as a new class of regulators for a variety of biological processes and have been suggested to play pivotal roles in cancer development and progression. Our current study found that a lncRNA, designated enhancing IL-6/STAT3 signaling activation (LEISA, ENST00000603468), functioned as an oncogenic lncRNA in lung adenocarcinoma (LAD), a major form of non-small cell lung carcinoma, which is one of the most frequently diagnosed malignancies with high morbidity and mortality worldwide, and was involved in the regulation of STAT3 induced IL-6 transcription. Our data showed that LEISA was highly expressed in, and correlated with the clinical progression and prognosis of LAD. Ectopic expression of LEISA promoted the proliferation and suppressed apoptosis of LAD cells in vitro and in vivo. Mechanistically, we demonstrated that LEISA recruited STAT3 to bind the promoter of IL-6 and upregulated IL-6 expression. Taken together, our work identifies LEISA as a potential diagnostic biomarker and therapeutic target for LAD.

RNF219/α-Catenin/LGALS3 Axis Promotes Hepatocellular Carcinoma Bone Metastasis and Associated Skeletal Complications.

The incidence of bone metastases in hepatocellular carcinoma (HCC) has increased prominently over the past decade owing to the prolonged overall survival of HCC patients. However, the mechanisms underlying HCC bone-metastasis remain largely unknown. In the current study, HCC-secreted lectin galactoside-binding soluble 3 (LGALS3) is found to be significantly upregulated and correlates with shorter bone-metastasis-free survival of HCC patients. Overexpression of LGALS3 enhances the metastatic capability of HCC cells to bone and induces skeletal-related events by forming a bone pre-metastatic niche via promoting osteoclast fusion and podosome formation. Mechanically, ubiquitin ligaseRNF219-meidated α-catenin degradation prompts YAP1/ß-catenin complex-dependent epigenetic modifications of LGALS3 promoter, resulting in LGALS3 upregulation and metastatic bone diseases. Importantly, treatment with verteporfin, a clinical drug for macular degeneration, decreases LGALS3 expression and effectively inhibits skeletal complications of HCC. These findings unveil a plausible role for HCC-secreted LGALS3 in pre-metastatic niche and can suggest a promising strategy for clinical intervention in HCC bone-metastasis.

AKT-induced lncRNA VAL promotes EMT-independent metastasis through diminishing Trim16-dependent Vimentin degradation.

Despite the importance of AKT overactivation in tumor progression, results from clinical trials of various AKT inhibitors remain suboptimal, suggesting that AKT-driven tumor metastasis needs to be further understood. Herein, based on long non-coding RNA (lncRNA) profiling induced by active AKT, we identify that VAL (Vimentin associated lncRNA, LINC01546), which is directly induced by AKT/STAT3 signaling, functions as a potent pro-metastatic molecule and is essential for active AKT-induced tumor invasion, metastasis and anoikis resistance in lung adenocarcinoma (LAD). Impressively, chemosynthetic siRNAs against VAL shows great therapeutic potential in AKT overactivation-driven metastasis. Interestingly, similar to activated AKT in LAD cells, although unable to induce epithelial-mesenchymal transition (EMT), VAL exerts potent pro-invasive and pro-metastatic effects through directly binding to Vimentin and competitively abrogating Trim16-depedent Vimentin polyubiquitination and degradation. Taken together, our study provides an interesting demonstration of a lncRNA-mediated mechanism for active AKT-driven EMT-independent LAD metastasis and indicates the great potential of targeting VAL or Vimentin stability as a therapeutic approach.

Neural progenitor cell pyroptosis contributes to Zika virus-induced brain atrophy and represents a therapeutic target.

Mounting evidence has associated Zika virus (ZIKV) infection with congenital malformations, including microcephaly, which raises global alarm. Nonetheless, mechanisms by which ZIKV disrupts neurogenesis and causes microcephaly are far from being understood. In this study, we discovered direct effects of ZIKV on neural progenitor cell development by inducing caspase-1- and gasdermin D (GSDMD)-mediated pyroptotic cell death, linking ZIKV infection with the development of microcephaly. Importantly, caspase-1 depletion or its inhibitor VX-765 treatment reduced ZIKV-induced inflammatory responses and pyroptosis, and substantially attenuated neuropathology and brain atrophy in vivo. Collectively, our data identify caspase-1- and GSDMD-mediated pyroptosis in neural progenitor cells as a previously unrecognized mechanism for ZIKV-related pathological effects during neural development, and also provide treatment options for ZIKV-associated diseases.

Antibiotic fidaxomicin is an RdRp inhibitor as a potential new therapeutic agent against Zika virus.

BACKGROUND: Zika virus (ZIKV) infection is a global health problem, and its complications, including congenital Zika syndrome and Guillain-Barré syndrome, constitute a continued threat to humans. Unfortunately, effective therapeutics against ZIKV infection are not available thus far. METHODS: We screened the compounds collection consisting of 1789 FDA-approved drugs by a computational docking method to obtain anti-ZIKV candidate compounds targeting ZIKV RNA-dependent RNA polymerase (RdRp). SPR (BIAcore) assay was employed to demonstrate the candidate compounds' direct binding to ZIKV RdRp, and polymerase activity assay was used to determine the inhibitory effect on ZIKV RdRp-catalyzed RNA synthesis. The antiviral effects on ZIKV in vitro and in vivo were detected in infected cultured cells and in Ifnar1-/- mice infected by ZIKV virus using plaque assay, western blotting, tissue immunofluorescence, and immunohistochemistry. RESULTS: Here, we report that a first-in-class macrocyclic antibiotic, which has been clinically used to treat Clostridium difficile infection, fidaxomicin, potently inhibits ZIKV replication in vitro and in vivo. Our data showed that fidaxomicin was effective against African and Asian lineage ZIKV in a wide variety of cell lines of various tissue origins, and prominently suppressed ZIKV infection and significantly improved survival of infected mice. In addition, fidaxomicin treatment reduced the virus load in the brains and testes, and alleviated ZIKV-associated pathological damages, such as paralysis, hunching, and neuronal necrosis in the cerebra. Furthermore, our mechanistic study showed that fidaxomicin directly bound ZIKV NS5 protein and inhibited the RNA synthesis-catalyzing activity of ZIKV RdRp. CONCLUSIONS: Our data suggest that fidaxomicin may represent an effective anti-ZIKV agent. In the light that fidaxomicin is already a clinically used drug, there might be a promising prospect in the development of fidaxomicin to be an antiviral therapeutic.