CRC-derived exosomes containing the RNA binding protein HuR promote lung cell proliferation by stabilizing c-Myc mRNA

LINC00460 contributes to colorectal cancer cell invasion

RESEARCH BACKGROUND

Colorectal cancer (CRC) is one of the most prevalent malignant tumors in the world. Research on long noncoding RNAs (LncRNAs) may illuminate tumorigenesis and progression of CRC.

METHODS

We screened long non-coding RNA LINC00460 as a new candidate, which promoted the development of CRC in two independent datasets (GSE39582 and GSE21510) from the Gene Expression Omnibus (GEO). In 98 CRC tissues, expression levels of LINC00460 were significantly increased in cancerous tissues compared to paired adjacent normal tissues (P < 0.001). In addition, in the most common CRC cell lines. LINC00460 expression was up-regulated compared to normal human intestinal epithelial cell line NCM460. siRNA was transfected into CRC cell lines. LINC00460 knockdown reduced cell invasion ability and did not affect cell proliferation. The association between LINC00460 expression and clinical pathological features and prognosis were also analyzed.

RESULTS

This increased expression was found to significantly correlate with lymph node metastasis (P = 0.002), distant metastasis (P = 0.045) and TNM stage (P < 0.001); but not related to age, gender, location of tumor, and histological grade. The overall survival (OS) in CRC patients with overexpression of LINC00460 was inferior to that with low expression (P = 0.0167). Multivariate Cox regression analyses indicated that LINC00460 expression, as well as TNM stage was an independent prognostic risk factor for patients with CRC.

CONCLUSION

These results showed that a higher expression level of LINC00460 might play an oncogenic role in colorectal cancer invasion and metastasis. It also proved that LINC00460 might be used as a potential diagnostic and prognostic biomarker in CRC patients.

Tumor-associated exosomes in cancer progression and therapeutic targets

Exosomes are small membrane vesicles that are released by cells into the extracellular environment. Tumor-associated exosomes (TAEs) are extracellular vesicles that play a significant role in cancer progression by mediating intercellular communication and contributing to various hallmarks of cancer. These vesicles carry a cargo of proteins, lipids, nucleic acids, and other biomolecules that can be transferred to recipient cells, modifying their behavior and promoting tumor growth, angiogenesis, immune modulation, and drug resistance. Several potential therapeutic targets within the TAEs cargo have been identified, including oncogenic proteins, miRNAs, tumor-associated antigens, immune checkpoint proteins, drug resistance proteins, and tissue factor. In this review, we will systematically summarize the biogenesis, composition, and function of TAEs in cancer progression and highlight potential therapeutic targets. Considering the complexity of exosome-mediated signaling and the pleiotropic effects of exosome cargoes has challenge in developing effective therapeutic strategies. Further research is needed to fully understand the role of TAEs in cancer and to develop effective therapies that target them. In particular, the development of strategies to block TAEs release, target TAEs cargo, inhibit TAEs uptake, and modulate TAEs content could provide novel approaches to cancer treatment.

M2 macrophage exosomes promote resistance to sorafenib in hepatocellular carcinoma cells via miR-200c-3p

OBJECTIVE

Sorafenib is a chemotherapeutic agent used to treat hepatocellular carcinoma (HCC). However, its clinical response rates are often low. Tumour-associated macrophages (TAMs) have been implicated in tumour resistance. The relationship between TAMs-derived exosomes and primary resistance to sorafenib in hepatocellular carcinoma is unclear.

METHODS

The study analysed RNA-SEQ data from TCGA-LIHC to explore the relationship between TAMs and sorafenib IC50. THP-1-induced M2 macrophages were used as a model to investigate the relationship between M2 macrophage exosomes and primary resistance to sorafenib in hepatocellular carcinoma cells using apoptosis, colony generation, cell viability and dual luciferase.

RESULTS

M2 macrophage score and sorafenib IC50 were positively correlated in hepatocellular carcinoma patients, M2 macrophage exosomes promoted sorafenib resistance in hepatocellular carcinoma cells, and M2-exo-miR-200c-3p facilitated the development of sorafenib resistance in hepatocellular carcinoma cells by mediating the activation of PI3K/AKT.

CONCLUSION

We propose and demonstrate for the first time that M2 macrophage exosomes promote sorafenib resistance in hepatocellular carcinoma, providing a new perspective for the clinical treatment of hepatocellular carcinoma patients.

Plasma-Derived Extracellular Vesicles and Non-Extracellular Vesicle Components from APCMin/+ Mice Promote Pro-Tumorigenic Activities and Activate Human Colonic Fibroblasts via the NF-κB Signaling Pathway

Colorectal cancer (CRC) is the third most prevalent cancer worldwide. Current studies have demonstrated that tumor-derived extracellular vesicles (EVs) from different cancer cell types modulate the fibroblast microenvironment to contribute to cancer development and progression. Here, we isolated and characterized circulating large EVs (LEVs), small EVs (SEVs) and non-EV entities released in the plasma from wild-type (WT) mice and the APCMin/+ CRC mice model. Our results showed that human colon fibroblasts exposed from APC-EVs, but not from WT-EVs, exhibited the phenotypes of cancer-associated fibroblasts (CAFs) through EV-mediated NF-κB pathway activation. Cytokine array analysis on secreted proteins revealed elevated levels of inflammatory cytokine implicated in cancer growth and metastasis. Finally, non-activated cells co-cultured with supernatant from fibroblasts treated with APC-EVs showed increased mRNA expressions of CAFs markers, the ECM, inflammatory cytokines, as well as the expression of genes controlled by NF-κB. Altogether, our work suggests that EVs and non-EV components from APCMin/+ mice are endowed with pro-tumorigenic activities and promoted inflammation and a CAF-like state by triggering NF-κB signaling in fibroblasts to support CRC growth and progression. These findings provide insight into the interaction between plasma-derived EVs and human cells and can be used to design new CRC diagnosis and prognosis tools.

Implications of c-Myc in the pathogenesis and treatment efficacy of urological cancers

Urological cancers, including prostate, bladder, and renal cancers, are significant causes of death and negatively impact the quality of life for patients. The development and progression of these cancers are linked to the dysregulation of molecular pathways. c-Myc, recognized as an oncogene, exhibits abnormal levels in various types of tumors, and current evidence supports the therapeutic targeting of c-Myc in cancer treatment. This review aims to elucidate the role of c-Myc in driving the progression of urological cancers. c-Myc functions to enhance tumorigenesis and has been documented to increase growth and metastasis in prostate, bladder, and renal cancers. Furthermore, the dysregulation of c-Myc can result in a diminished response to therapy in these cancers. Non-coding RNAs, β-catenin, and XIAP are among the regulators of c-Myc in urological cancers. Targeting and suppressing c-Myc therapeutically for the treatment of these cancers has been explored. Additionally, the expression level of c-Myc may serve as a prognostic factor in clinical settings.

The multifaceted role of extracellular vesicles (EVs) in colorectal cancer: metastasis, immune suppression, therapy resistance, and autophagy crosstalk

Extracellular vesicles (EVs) are lipid bilayer structures released by all cells and widely distributed in all biological fluids. EVs are implicated in diverse physiopathological processes by orchestrating cell-cell communication. Colorectal cancer (CRC) is one of the most common cancers worldwide, with metastasis being the leading cause of mortality in CRC patients. EVs contribute significantly to the advancement and spread of CRC by transferring their cargo, which includes lipids, proteins, RNAs, and DNAs, to neighboring or distant cells. Besides, they can serve as non-invasive diagnostic and prognostic biomarkers for early detection of CRC or be harnessed as effective carriers for delivering therapeutic agents. Autophagy is an essential cellular process that serves to remove damaged proteins and organelles by lysosomal degradation to maintain cellular homeostasis. Autophagy and EV release are coordinately activated in tumor cells and share common factors and regulatory mechanisms. Although the significance of autophagy and EVs in cancer is well established, the exact mechanism of their interplay in tumor development is obscure. This review focuses on examining the specific functions of EVs in various aspects of CRC, including progression, metastasis, immune regulation, and therapy resistance. Further, we overview emerging discoveries relevant to autophagy and EVs crosstalk in CRC.

Bacoside a inhibits the growth of glioma by promoting apoptosis and autophagy in U251 and U87 cells

Bacoside A (gypenoside, Gyp) is a potent bioactive compound derived from Gynostemma pentaphyllum, known to exert inhibitory effects on various malignant tumors. However, the effects of Gyp on glioma as well as the underlying mechanisms remain unclear. In the present study, we first conducted a comprehensive investigation into the anti-glioma potential of gypenosides using network pharmacology to identify potential glioma-related targets. Protein-protein interaction networks were assembled, and GO and KEGG enrichment analyses were performed for shared targets. Experimental validation involved assessing the viability of U251 and U87 cell lines using the MTS method. Furthermore, trans-well and scratch migration assays evaluated the cell migration, while flow cytometry and Hoechst 33342 staining were utilized for apoptosis assessment. The study also monitored changes in autophagy flow through fluorescence microscopy. The expression levels of proteins pertinent to migration, apoptosis, and autophagy were tested using Western blotting. Findings revealed that Gyp upregulated apoptosis-related proteins (Bax and cleaved caspase-9), downregulated anti-apoptotic protein Bcl-2, and migration-associated matrix metalloproteinases (MMP-2 and MMP-9). Furthermore, autophagy-related proteins (Beclin1 and LC3 II) were upregulated, and p62 protein expression was downregulated. Gyp displayed considerable potential in suppressing glioma progression by inhibiting cell proliferation, invasion, and migration and promoting apoptosis and autophagy. Gyp may offer potential clinical therapeutic choices in glioma management.

Lactadherin immunoblockade in small extracellular vesicles inhibits sEV-mediated increase of pro-metastatic capacities

BACKGROUND

Tumor-derived small extracellular vesicles (sEVs) can promote tumorigenic and metastatic capacities in less aggressive recipient cells mainly through the biomolecules in their cargo. However, despite recent advances, the specific molecules orchestrating these changes are not completely defined. Lactadherin is a secreted glycoprotein typically found in the milk fat globule membrane. Its overexpression has been associated with increased tumorigenesis and metastasis in breast cancer (BC) and other tumors. However, neither its presence in sEVs secreted by BC cells, nor its role in sEV-mediated intercellular communication have been described. The present study focused on the role of lactadherin-containing sEVs from metastatic MDA-MB-231 triple-negative BC (TNBC) cells (sEV-MDA231) in the promotion of pro-metastatic capacities in non-tumorigenic and non-metastatic recipient cells in vitro, as well as their pro-metastatic role in a murine model of peritoneal carcinomatosis.

RESULTS

We show that lactadherin is present in sEVs secreted by BC cells and it is higher in sEV-MDA231 compared with the other BC cell-secreted sEVs measured through ELISA. Incubation of non-metastatic recipient cells with sEV-MDA231 increases their migration and, to some extent, their tumoroid formation capacity but not their anchorage-independent growth. Remarkably, lactadherin blockade in sEV-MDA231 results in a significant decrease of those sEV-mediated changes in vitro. Similarly, intraperitoneally treatment of mice with MDA-MB-231 BC cells and sEV-MDA231 greatly increase the formation of malignant ascites and tumor micronodules, effects that were significantly inhibited when lactadherin was previously blocked in those sEV-MDA231.

CONCLUSIONS

As to our knowledge, our study provides the first evidence on the role of lactadherin in metastatic BC cell-secreted sEVs as promoter of: (i) metastatic capacities in less aggressive recipient cells, and ii) the formation of malignant ascites and metastatic tumor nodules. These results increase our understanding on the role of lactadherin in sEVs as promoter of metastatic capacities which can be used as a therapeutic option for BC and other malignancies.

Targeting the RNA-Binding Protein HuR in Cancer

The RNA-binding protein human antigen R (HuR) is a well-established regulator of gene expression at the posttranscriptional level. Its dysregulation has been implicated in various human diseases, particularly cancer. In cancer, HuR is considered "active" when it shows increased subcellular localization in the cytoplasm, in addition to its normal nuclear localization. Cytoplasmic HuR plays a crucial role in stabilizing and enhancing the translation of prosurvival mRNAs that are involved in stress responses relevant to cancer progression, such as hypoxia, radiotherapy, and chemotherapy. In general, due to HuR's abundance and function in cancer cells compared with normal cells, it is an appealing target for oncology research. Exploiting the principles underlying HuR's role in tumorigenesis and resistance to stressors, targeting HuR has the potential for synergy with existing and novel oncologic therapies. This review aims to explore HuR's role in homeostasis and cancer pathophysiology, as well as current targeting strategies, which include silencing HuR expression, preventing its translocation and dimerization from the nucleus to the cytoplasm, and inhibiting mRNA binding. Furthermore, this review will discuss recent studies investigating the potential synergy between HuR inhibition and traditional chemotherapeutics.

Extracellular vesicles could be a putative posttranscriptional regulatory mechanism that shapes intracellular RNA levels in Plasmodium falciparum

Plasmodium falciparum secretes extracellular vesicles (PfEVs) that contain parasite-derived RNA. However, the significance of the secreted RNA remains unexplored. Here, we compare secreted and intracellular RNA from asexual cultures of six P. falciparum lines. We find that secretion of RNA via extracellular vesicles is not only periodic throughout the asexual intraerythrocytic developmental cycle but is also highly conserved across P. falciparum isolates. We further demonstrate that the phases of RNA secreted via extracellular vesicles are discernibly shifted compared to those of the intracellular RNA within the secreting whole parasite. Finally, transcripts of genes with no known function during the asexual intraerythrocytic developmental cycle are enriched in PfEVs compared to the whole parasite. We conclude that the secretion of extracellular vesicles could be a putative posttranscriptional RNA regulation mechanism that is part of or synergise the classic RNA decay processes to maintain intracellular RNA levels in P. falciparum.

Extracellular vesicle-associated IGF2BP3 tunes Ewing sarcoma cell migration and affects PI3K/Akt pathway in neighboring cells

Ewing sarcoma (EWS) is a challenging pediatric cancer characterized by vast intra-tumor heterogeneity. We evaluated the RNA-binding protein IGF2BP3, whose high expression correlates with a poor prognosis and an elevated tendency of metastases, as a possible soluble mediator of inter-cellular communication in EWS. Our data demonstrate that (i) IGF2BP3 is detected in cell supernatants, and it is released inside extracellular vesicles (EVs); (ii) EVs from IGF2BP3-positive or IGF2BP3-negative EWS cells reciprocally affect cell migration but not the proliferation of EWS recipient cells; (iii) EVs derived from IGF2BP3-silenced cells have a distinct miRNA cargo profile and inhibit the PI3K/Akt pathway in recipient cells; (iv) the 11 common differentially expressed miRNAs associated with IGF2BP3-positive and IGF2BP3-negative EVs correctly group IGF2BP3-positive and IGF2BP3-negative clinical tissue specimens. Overall, our data suggest that IGF2BP3 can participate in the modulation of phenotypic heterogeneity.

Low Molecular Weight Inhibitors Targeting the RNA-Binding Protein HuR

The RNA-binding protein human antigen R (HuR) regulates stability, translation, and nucleus-to-cytoplasm shuttling of its target mRNAs. This protein has been progressively recognized as a relevant therapeutic target for several pathologies, like cancer, neurodegeneration, as well as inflammation. Inhibitors of mRNA binding to HuR might thus be beneficial against a variety of diseases. Here, we present the rational identification of structurally novel HuR inhibitors. In particular, by combining chemoinformatic approaches, high-throughput virtual screening, and RNA-protein pulldown assays, we demonstrate that the 4-(2-(2,4,6-trioxotetrahydropyrimidin-5(2H)-ylidene)hydrazineyl)benzoate ligand exhibits a dose-dependent HuR inhibition effect in binding experiments. Importantly, the chemical scaffold is new with respect to the currently known HuR inhibitors, opening up a new avenue for the design of pharmaceutical agents targeting this important protein.

Expression of targets of the RNA-binding protein AUF-1 in human airway epithelium indicates its role in cellular senescence and inflammation

Introduction

The RNA-binding protein AU-rich-element factor-1 (AUF-1) participates to posttranscriptional regulation of genes involved in inflammation and cellular senescence, two pathogenic mechanisms of chronic obstructive pulmonary disease (COPD). Decreased AUF-1 expression was described in bronchiolar epithelium of COPD patients versus controls and in vitro cytokine- and cigarette smoke-challenged human airway epithelial cells, prompting the identification of epithelial AUF-1-targeted transcripts and function, and investigation on the mechanism of its loss.

Results

RNA immunoprecipitation-sequencing (RIP-Seq) identified, in the human airway epithelial cell line BEAS-2B, 494 AUF-1-bound mRNAs enriched in their 3'-untranslated regions for a Guanine-Cytosine (GC)-rich binding motif. AUF-1 association with selected transcripts and with a synthetic GC-rich motif were validated by biotin pulldown. AUF-1-targets' steady-state levels were equally affected by partial or near-total AUF-1 loss induced by cytomix (TNFα/IL1β/IFNγ/10 nM each) and siRNA, respectively, with differential transcript decay rates. Cytomix-mediated decrease in AUF-1 levels in BEAS-2B and primary human small-airways epithelium (HSAEC) was replicated by treatment with the senescence- inducer compound etoposide and associated with readouts of cell-cycle arrest, increase in lysosomal damage and senescence-associated secretory phenotype (SASP) factors, and with AUF-1 transfer in extracellular vesicles, detected by transmission electron microscopy and immunoblotting. Extensive in-silico and genome ontology analysis found, consistent with AUF-1 functions, enriched RIP-Seq-derived AUF-1-targets in COPD-related pathways involved in inflammation, senescence, gene regulation and also in the public SASP proteome atlas; AUF-1 target signature was also significantly represented in multiple transcriptomic COPD databases generated from primary HSAEC, from lung tissue and from single-cell RNA-sequencing, displaying a predominant downregulation of expression.

Discussion

Loss of intracellular AUF-1 may alter posttranscriptional regulation of targets particularly relevant for protection of genomic integrity and gene regulation, thus concurring to airway epithelial inflammatory responses related to oxidative stress and accelerated aging. Exosomal-associated AUF-1 may in turn preserve bound RNA targets and sustain their function, participating to spreading of inflammation and senescence to neighbouring cells.

Extracellular Vesicles in Colorectal Cancer: From Tumor Growth and Metastasis to Biomarkers and Nanomedications

Colorectal cancer (CRC) is a leading public health concern due to its incidence and high mortality rates, highlighting the requirement of an early diagnosis. Evaluation of circulating extracellular vesicles (EVs) might constitute a noninvasive and reliable approach for CRC detection and for patient follow-up because EVs display the molecular features of the cells they originate. EVs are released by almost all cell types and are mainly categorized as exosomes originating from exocytosis of intraluminal vesicles from multivesicular bodies, ectosomes resulting from outward budding of the plasma membrane and apoptotic bodies' ensuing cell shrinkage. These vesicles play a critical role in intercellular communications during physiological and pathological processes. They facilitate CRC progression and premetastatic niche formation, and they enable transfer of chemotherapy resistance to sensitive cells through the local or remote delivery of their lipid, nucleic acid and protein content. On another note, their stability in the bloodstream, their permeation in tissues and their sheltering of packaged material make engineered EVs suitable vectors for efficient delivery of tracers and therapeutic agents for tumor imaging or treatment. Here, we focus on the physiopathological role of EVs in CRCs, their value in the diagnosis and prognosis and ongoing investigations into therapeutic approaches.

Formation of pre-metastatic niches induced by tumor extracellular vesicles in lung metastasis

There are a number of malignant tumors that metastasize into the lung as one of their most common sites of dissemination. The successful infiltration of tumor cells into distant organs is the result of the cooperation between tumor cells and distant host cells. When tumor cells have not yet reached distant organs, in situ tumor cells secrete extracellular vesicles (EVs) carrying important biological information. In recent years, scholars have found that tumor cells-derived EVs act as the bridge between orthotopic tumors and secondary metastases by promoting the formation of a pre-metastatic niche (PMN), which plays a key role in awakening dormant circulating tumor cells and promoting tumor cell colonization. This review provides an overview of multiple routes and mechanisms underlying PMN formation induced by EVs and summaries study findings that underline a potential role of EVs in the intervention of lung PMN, both as a target or a carrier for drug design. In this review, the underlying mechanisms of EVs in lung PMN formation are highlighted as well as potential applications to lung metastasis diagnosis and treatment.

CircREOS suppresses lipid synthesis and osteosarcoma progression through inhibiting HuR-mediated MYC activation

MYC proto-oncogene (MYC) is a transcription factor among the most commonly activated oncoproteins, playing vital roles in lipid metabolism and tumor aggressiveness with broad effects. However, it is still largely unknown about the regulating mechanisms of MYC in osteosarcoma (OS). In this study, we identify a circRNA with Reduced Expression in OS (termed as circREOS) generated from MYC gene, as a novel regulator of MYC and OS progression. CircREOS is down-regulated in OS cells and localized in the nucleus. CircREOS suppresses MYC expression, lipid metabolism and growth, invasion in OS cells. Mechanically, circREOS physically interacts with HuR (human antigen R) protein, and subsequently restrains its binding and activation on the 3'-UTR (untranslated region) of MYC mRNA, resulting in down-regulation of MYC and inhibition of OS. Moreover, circREOS serves as a tumor suppressor via targeting lipid metabolism. CircREOS reduces FASN expression and lipid accumulation through inhibiting MYC-facilitated FASN regulation. Taken together, these results indicate that circREOS suppress lipid synthesis and OS progression through inhibiting HuR-mediated MYC activation, providing a potential therapeutic target for OS.

IMP1/IGF2BP1 in human colorectal cancer extracellular vesicles

Colorectal cancer (CRC) is a leading cause of cancer-related death. There is an urgent need for new methods of early CRC detection and monitoring to improve patient outcomes. Extracellular vesicles (EVs) are secreted, lipid-bilayer bound, nanoparticles that carry biological cargo throughout the body and in turn exhibit cancer-related biomarker potential. RNA binding proteins (RBPs) are posttranscriptional regulators of gene expression that may provide a link between host cell gene expression and EV phenotypes. Insulin-like growth factor 2 RNA binding protein 1 (IGF2BP1/IMP1) is an RBP that is highly expressed in CRC with higher levels of expression correlating with poor prognosis. IMP1 binds and potently regulates tumor-associated transcripts that may impact CRC EV phenotypes. Our objective was to test whether IMP1 expression levels impact EV secretion and/or cargo. We used RNA sequencing, in vitro CRC cell lines, ex vivo colonoid models, and xenograft mice to test the hypothesis that IMP1 influences EV secretion and/or cargo in human CRC. Our data demonstrate that IMP1 modulates the RNA expression of transcripts associated with extracellular vesicle pathway regulation, but it has no effect on EV secretion levels in vitro or in vivo. Rather, IMP1 appears to affect EV regulation by directly entering EVs in a transformation-dependent manner. These findings suggest that IMP1 has the ability to shape EV cargo in human CRC, which could serve as a diagnostic/prognostic circulating tumor biomarker.NEW & NOTEWORTHY This work demonstrates that the RNA binding protein IGF2BP1/IMP1 alters the transcript profile of colorectal cancer cell (CRC) mRNAs from extracellular vesicle (EV) pathways. IMP1 does not alter EV production or secretion in vitro or in vivo, but rather enters CRC cells where it may further impact EV cargo. Our work shows that IMP1 has the ability to shape EV cargo in human CRC, which could serve as a diagnostic/prognostic circulating tumor biomarker.

Role of Acute Myeloid Leukemia (AML)-Derived exosomes in tumor progression and survival

Acute myeloid leukemia (AML) is a quickly aggressive hematopoietic disorder that progress due to the accumulation and clonal expansion of immature myeloid cells. Despite the latest developments in AML treatment, repeated relapses and drug resistance remain one of the major challenges in treatment of leukemia. Currently, it is well known that the components of the tumor microenvironment such as cellular and non-cellular elements play a critical function in treatment failures of AML, also they are most common cause of complications including suppression of hematopoiesis. Exosomes are membrane-bound extracellular vesicles (EVs) that transfer signaling molecules and have attracted a large amount of attention due to their important role in inter-cellular communication in health and disease. Exosomes participate in the survival and chemoresistance of many leukemia through transferring their rich cargos of molecules including miRNAs, growth factors, and cytokines. The key producers of exosomes that mainly participate to AML pathogenesis are bone marrow mesenchymal stem cell (BMSCs) and AML cell themselves. These cells release an enormous number of exosomes that affect several target cells such as natural killer (NK) and hematopoietic stem cells to the development of leukemia proliferation and progression. In the present study, a comprehensive review of the literature has been done to briefly discuss the biology of exosomes and highlight the role of exosomes derived from AML in the progress of acute myeloid leukemia.

The Role of RNA-Binding Protein HuR in Lung Cancer by RNA Sequencing Analysis

Background: The overexpression of human antigen R (HuR) has been proven in various types of cancer and is associated with the poor survival lung cancer patients. HuR overexpression stabilizes the mRNA of tumor-promoting genes by binding with 3′-UTR AU-rich elements. However, the role of HuR in the proliferation of lung cancer is unclear.

Methods: HuR expression was assessed using immunohistochemistry of tumor tissue samples from ten patients with lung cancer and ten patients with benign lung disease. Gene, protein, mRNA, and lncRNA changes in A549 HuR knockdown (KD) cells were assessed by single-cell RNA sequencing analysis. Furthermore, cell proliferation, migration, and invasion were determined by Cell Counting Kit-8 (CCK-8) assays and Transwell assays with or without Matrigel. The cell cycle was assessed by propidium iodide staining. The protein level, mRNA level and half-life of PLK1 were detected by western blotting and RT-qPCR.

Results: In clinical patients, the expression of HuR was significantly higher in lung cancer patients than in patients with benign lung disease. RNA sequencing analysis of A549 HuR knockdown cells revealed that the main function of HuR was related to ribonucleoprotein complex biogenesis. HuR was found to regulate signaling pathways mainly related to the spliceosome, RNA transport and the cell cycle. HuR KD suppressed the proliferation, migration and invasion of A549 cells, indicating its promotive role in these processes.

Conclusion: These results demonstrate that HuR plays an important role in the progression of lung cancer.