RNA binding protein FXR1-miR301a-3p axis contributes to p21WAF1 degradation in oral cancer

Diagnostic value of exosome-derived lncRNA PITPNA-AS1 in lung cancer

Background

Lung cancer is one of the most lethal types of cancer, and effective diagnostic biomarkers are required. There is increasing evidences that exosome-secreted lncRNAs could play an important role in lung cancer diagnosis. However, the diagnostic value and molecular mechanism of the key lncRNA PITPNA-AS1 in lung cancer remain unclear.

Methods

qRT-PCR was conducted to determine the levels of exosomal lncRNA PITPNA-AS1 in pleural effusions from lung adenocarcinoma, squamous cell lung carcinoma, and small cell lung cancer patients. Receiver operating characteristic (ROC) curve analyses were used to evaluate the diagnostic accuracy of PITPNA-AS1. Its role in lung cancer development was determined by a series of experiments, including CCK-8, flow cytometry, and transwell assays. RNA pull-down and RNA immunoprecipitation assays were carried out to examine the interaction between PITPNA-AS1 and Fragile X messenger ribonucleoprotein 1 (FMR1).

Results

We discovered PITPNA-AS1 in exosomes from lung cancer patients. Its expression was significantly increased in lung cancer patients compared to non-cancer patients, and it was strongly associated with tumor stage, lymph node metastasis, and distant metastasis in all lung cancer subtypes assessed (all p<0.05). ROC curve analyses demonstrated that exosomal PITPNA-AS1 had a high accuracy for differentiating among lung cancer subtypes. Furthermore, PITPNA-AS1 boosted H1299 and A549 cell proliferation, migration, and invasion. Mechanistically, via direct interaction, PITPNA-AS1 increased FMR1 stability by preventing its ubiquitination.

Conclusions

These results reveal that exosome-derived lncRNA PITPNA-AS1 acts as an oncogene to promote malignant biological behaviors and is a promising diagnostic biomarker in lung cancer.

The prognostic significance of fragile X mental retardation syndrome-related protein 1 (FXR1) in breast cancer

Background

Breast cancer (BC) is a highly heterogeneous disease with variable histological appearance, biological features, clinical outcomes, and treatment responses. The number of BC cases in Saudi Arabia has more than tripled during the last 17 years to constitute 30% of all cancer cases in women. Therefore, greater efforts are needed to evaluate prognostic factors for BC in Saudi Arabia to improve prognostication and provide more personalized therapy. Recently, fragile X mental retardation syndrome-related protein 1 (FXR1) was identified as a novel biomarker that contributes to oncogenesis; however, its role in BC has not been well studied. This study aims to evaluate the clinicopathological significance of FXR1 in women with primary BC.

Methods

The protein levels of FXR1 in BC tissue samples (n=100) were determined immunohistochemically. The associations between FXR1 levels and clinicopathological parameters and outcomes were evaluated, and significant associations were validated by assessing FXR1 mRNA levels in publicly available cohorts in the BC Gene-Expression Miner database (version 5).

Results

High protein levels of FXR1 were significantly associated with tumor aggressiveness, including stage IIB and IIIC and hormone receptor negativity, the triple-negative BC (TNBC) subtype, and poor outcomes. Consistent with the protein results, high mRNA levels of FXR1 were significantly associated with hormone receptor negativity and the TNBC subtype.

Conclusions

This study revealed that FXR1 is a prognostic factor for poor prognosis in women with BC. Further functional studies are needed to confirm its role in aggressive BC and its value as a therapeutic target.

Stepwise single-cell data identifies RNA binding proteins associated with the development of head and neck cancer and tumor microenvironment remodeling

Background: Head and neck squamous cell carcinoma (HNSC) is a globally prevalent malignancy with high mortality rates. RNA-binding proteins (RBPs) are crucial regulators of gene expression and play significant roles in cancer development. However, a comprehensive understanding of RBPs at the single-cell level in HNSC remains limited.ObjectiveThis study aims to investigate the role of RBPs in the stepwise progression of HNSC at the single-cell level, focusing on their expression patterns, prognostic potential, and involvement in key signaling pathways.MethodsWe analyzed single-cell RNA-sequencing data from HNSC samples across four stages, from normal tissue to precancerous leukoplakia, then to primary cancer and finally to metastatic tumors, examining the expression of 2141 previously reported RBPs. We identified RBP-based cell clusters and explored their associations with disease stages, cell types, and cancer progression. A prognostic risk model was developed based on RBPs with significant relevance to patient outcomes.ResultsRBPs displayed distinct cell type-specific expression patterns across different stages of HNSC. We found a significant correlation between RBP-based cell clusters and cancer progression. Notably, a prognostic model was constructed using RBPs such as CELF2, which showed downregulation from early leukoplakia to advanced cancer stages. Fibroblast RBPs were dynamically regulated, particularly in extracellular matrix remodeling, with key proteins like CFL1 and PFN1 linked to improved prognosis. Furthermore, we identified heterogeneity in RBP regulation of the Macrophage Migration Inhibitory Factor (MIF) signaling pathway across cell types during the precancerous stage.ConclusionsOur findings highlight the crucial roles of RBPs in HNSC progression and suggest their potential as therapeutic targets and prognostic markers, offering insights into personalized treatment strategies.

Multifaceted role of microRNA-301a in human cancer: from biomarker potential to therapeutic targeting

With the growing data on microRNA (miRNA) expression in tissues and circulation, there is increasing evidence for the potential of microRNAs to serve as biomarkers in cancer diagnosis and prognosis, as well as novel therapeutic targets. The expression level of miRNA-301a (miR-301a) is altered in a wide range of human tumor types, and numerous studies have revealed the roles of miR-301a in tumorigenesis and tumor progression. Herein, we comprehensively summarize, compare, and contrast the research advancements on the role of miR-301a in different cancers. Differential expression patterns of miR-301a in tissues and biofluids are implicated in cancer diagnosis, treatment response, and prognosis. MiR-301a modulates the expression of multiple genes, other noncoding RNAs, and signaling cascade via direct or indirect regulation in human cancer proliferation, migration, invasion, angiogenesis, and radio- or chemotherapy resistance. Cancer cell-associated miR-301a affects the tumor microenvironment through the alteration of immune function and cancer metabolism. These findings highlight the functional roles, clinical implications, and therapeutic relevance of miR-301a in various human cancers.

PRMT5-mediated arginine methylation of FXR1 is essential for RNA binding in cancer cells

Emerging evidence indicates that arginine methylation promotes the stability of arginine-glycine-rich (RGG) motif-containing RNA-binding proteins (RBPs) and regulates gene expression. Here, we report that post-translational modification of FXR1 enhances the binding with mRNAs and is involved in cancer cell growth and proliferation. Independent point mutations in arginine residues of FXR1's nuclear export signal (R386 and R388) and RGG (R453, R455 and R459) domains prevent it from binding to RNAs that form G-quadruplex (G4) RNA structures. Disruption of G4-RNA structures by lithium chloride failed to bind with FXR1, indicating its preference for G4-RNA structure containing mRNAs. Furthermore, loss-of-function of PRMT5 inhibited FXR1 methylation both in vivo and in vitro, affecting FXR1 protein stability, inhibiting RNA-binding activity and cancer cell growth and proliferation. Finally, the enhanced crosslinking and immunoprecipitation (eCLIP) analyses reveal that FXR1 binds with the G4-enriched mRNA targets such as AHNAK, MAP1B, AHNAK2, HUWE1, DYNC1H1 and UBR4 and controls its mRNA expression in cancer cells. Our findings suggest that PRMT5-mediated FXR1 methylation is required for RNA/G4-RNA binding, which promotes gene expression in cancer cells. Thus, FXR1's structural characteristics and affinity for RNAs preferentially G4 regions provide new insights into the molecular mechanism of FXR1 in oral cancer cells.

RNA-binding protein HuR reprograms immune T cells and promotes oral squamous cell carcinoma

Hu Antigen R, also known as ELAVL1 (HuR), is a key posttranscriptional regulator in eukaryotic cells. HuR overexpression promotes several malignancies, including head and neck squamous cell carcinoma (HNSCC). However, its immune dysfunction-associated tumorigenesis pathways remain unknown. We examined HuR's effects on oral malignancies and immune cell function in vitro and in vivo using oral carcinoma cells and transgenic HuR knockout (KO) mice. CRISPR/Cas9-mediated HuR deletion in mice syngeneic oral cancer cells eliminated colony formation and tumor development. HuR-KO tumors had a lower tumor volume, fewer CD4+CD25+FoxP3+ regulatory T cells, and more CD8+ T cells, suggesting that HuR may suppress the immune response during oral cancer progression. In contrast, HuR KO oral epithelial tissues are resistant to 4NQO-induced oral malignancies compared to control tumor-bearing mice. HuR KO mice showed fewer Tregs and greater IFN levels than WT tumor-bearing mice, suggesting anticancer activity. Finally, the HuR inhibitor pyrvinium pamoate lowers tumor burden by enhancing CD8+ infiltration at the expense of CD4+, suggesting anticancer benefits. Thus, HuR-dependent oral neoplasia relies on immunological dysfunction, suggesting that decreasing HuR may boost antitumor potential and offer a novel HNSCC therapy.

The multifaceted role of Fragile X-Related Protein 1 (FXR1) in cellular processes: an updated review on cancer and clinical applications

RNA-binding proteins (RBPs) modulate the expression level of several target RNAs (such as mRNAs) post-transcriptionally through interactions with unique binding sites in the 3'-untranslated region. There is mounting information that suggests RBP dysregulation plays a significant role in carcinogenesis. However, the function of FMR1 autosomal homolog 1(FXR1) in malignancies is just beginning to be unveiled. Due to the diversity of their RNA-binding domains and functional adaptability, FXR1 can regulate diverse transcript processing. Changes in FXR1 interaction with RNA networks have been linked to the emergence of cancer, although the theoretical framework defining these alterations in interaction is insufficient. Alteration in FXR1 expression or localization has been linked to the mRNAs of cancer suppressor genes, cancer-causing genes, and genes involved in genomic expression stability. In particular, FXR1-mediated gene regulation involves in several cellular phenomena related to cancer growth, metastasis, epithelial-mesenchymal transition, senescence, apoptosis, and angiogenesis. FXR1 dysregulation has been implicated in diverse cancer types, suggesting its diagnostic and therapeutic potential. However, the molecular mechanisms and biological effects of FXR1 regulation in cancer have yet to be understood. This review highlights the current knowledge of FXR1 expression and function in various cancer situations, emphasizing its functional variety and complexity. We further address the challenges and opportunities of targeting FXR1 for cancer diagnosis and treatment and propose future directions for FXR1 research in oncology. This work intends to provide an in-depth review of FXR1 as an emerging oncotarget with multiple roles and implications in cancer biology and therapy.

Cumulative effects of weakly repressive regulatory regions in the 3' UTR maintain PD-1 expression homeostasis in mammals

PD-1 has become a common target for cancer treatment. However, the molecular regulation of PD-1 expression homeostasis remains unclear. Here we report the PD-1 3' UTR can dramatically repress gene expression via promoting mRNA decay. Deletion of the PD-1 3' UTR inhibits T cell activity and promotes T-ALL cell proliferation. Interestingly, the robust repression is attributable to cumulative effects of many weak regulatory regions, which we show together are better able to maintain PD-1 expression homeostasis. We further identify several RNA binding proteins (RBPs) that modulate PD-1 expression via the 3' UTR, including IGF2BP2, RBM38, SRSF7, and SRSF4. Moreover, despite rapid evolution, PD-1 3' UTRs are functionally conserved and strongly repress gene expression through many common RBP binding sites. These findings reveal a previously unrecognized mechanism of maintaining PD-1 expression homeostasis and might represent a general model for how small regulatory effects play big roles in regulation of gene expression and biology.

FXR1 facilitates axitinib resistance in clear cell renal cell carcinoma via regulating KEAP1/Nrf2 signaling pathway

Axitinib is emerging as a first-line combination treatment drug for metastatic renal cell carcinoma, but the acquired resistance significantly bothers the treatment efficacy. This article is to investigate the impact of fragile X mental retardation autosomal homolog 1 (FXR1) and its mechanistic involvement with Kelch-like epoxy chloropropan-associated protein 1 (KEAP1)/NF-E2-related factor 2 (Nrf2) pathway on cell resistance to axitinib in clear cell renal cell carcinoma (ccRCC). Establishment of axitinib resistance cells (786-O, Caki-1, 786-O/axitinib, or Caki-1/axitinib) was made, and the cells were then transfected with sh-FXR1, or co-transfected with sh-FXR1 and sh-KEAP1. The quantitative real-time PCR (qRT-PCR) and western blotting assays were employed to measure the expression of FXR1, KEAP1, Nrf2, LC3 II/I, Beclin 1, p62, MDR-1, and MRP-1. In addition, the binding between FXR1 and KEAP1 was verified by RNA-immunoprecipitation and RNA pull-down assays, and FXR1-dependent KEAP1 mRNA degradation was determined. Herein, FXR1 was demonstrated to be overexpressed in ccRCC cells, and showed higher expression in 786-O/axitinib and Caki-1/axitinib cells. Mechanistically, FXR1 enriched KEAP1 mRNA, and pulled downed by biotinylated KEAP1 probes. Results of RNA stability assay reveled that KEAP mRNA stability was suppressed by FXR1. Furthermore, knockdown of FXR1 promoted cell apoptosis and showed a restrained feature on cell resistance to axitinib. Of note, KEAP1 knockdown suppressed cell autophagy, oxidative stress, resistance to axitinib, and promoted apoptosis, despite FXR1 was downregulated in ccRCC cells. In conclusion, FXR1 played an encouraging role in ccRCC cell resistance to axitinib by modulating KEAP/Nrf2 pathway.

AMG232 inhibits angiogenesis in glioma through the p53-RBM4-VEGFR2 pathway

AMG232 effectively inhibits cancers with wild-type p53 (also known as TP53) by reactivating p53, but whether it inhibits glioma angiogenesis remains unclear. This study confirms that AMG232 inhibits the proliferation of glioma endothelial cells (GECs) in a dose-dependent manner and inhibits the angiogenesis of GECs. p53 and RNA-binding motif protein 4 (RBM4) were expressed at low levels in GECs, while MDM2 and vascular endothelial growth factor receptor 2 (VEGFR2, also known as KDR) were highly expressed. In vitro and in vivo experiments confirmed that AMG232 upregulated p53 and RBM4, and downregulated MDM2 and VEGFR2 by blocking the MDM2-p53 interaction. Both p53 silencing and RBM4 silencing significantly upregulated the expression of VEGFR2, promoted the proliferation, migration and tube formation of GECs, and reversed the effects of AMG232 on downregulating VEGFR2 and inhibiting the angiogenesis of GECs. AMG232 increased RBM4 expression by upregulating p53, and p53 bound to RBM4 and promoted its transcription. RBM4 bound to and shortened the half-life of VEGFR2, promoting its degradation. Finally, AMG232 produced a significant decrease in new vessels and hemoglobin content in vivo. This study proves that AMG232 inhibits glioma angiogenesis by blocking the MDM2-p53 interaction, in which the p53-RBM4-VEGFR2 pathway plays an important role.

RNA-binding proteins: Underestimated contributors in tumorigenesis

mRNA export, translation, splicing, cleavage or capping determine mRNA stability, which represents one of the primary aspects regulating gene expression and function. RNA-binding proteins (RBPs) bind to their target mRNAs to regulate multiple cell functions by increasing or reducing their stability. In recent decades, studies of the role of RBPs in tumorigenesis have revealed an increasing number of proteins impacting the prognosis, diagnosis and cancer treatment. Several RBPs have been identified based on their interactions with oncogenes or tumor suppressor genes in human cancers, which are involved in apoptosis, the epithelial-mesenchymal transition (EMT), DNA repair, autophagy, cell proliferation, immune response, metabolism, and the regulation of noncoding RNAs. In this review, we propose a model showing how RBP mutations influence tumorigenesis, and we update the current knowledge regarding the molecular mechanism by which RBPs regulate cancer. Special attention is being devoted to RBPs that represent prognostic and diagnostic factors in cancer patients.

Cooperation and competition by RNA-binding proteins in cancer

Post-transcriptional regulation of gene expression plays a major role in determining the cellular proteome in health and disease. Post-transcriptional control mechanisms are disrupted in many cancers, contributing to multiple processes of tumorigenesis. RNA-binding proteins (RBPs), the main post-transcriptional regulators, often show altered expression and activity in cancer cells. Dysregulation of RBPs contributes to many cancer phenotypes, functioning in complex regulatory networks with other cellular players such as non-coding RNAs, signaling mediators and transcription factors to alter the expression of oncogenes and tumor suppressor genes. RBPs often function combinatorially, based on their binding to target sequences/structures on shared mRNA targets, to regulate the expression of cancer-related genes. This gives rise to cooperativity and competition between RBPs in mRNA binding and resultant functional outcomes in post-transcriptional processes such as mRNA splicing, stability, export and translation. Cooperation and competition is also observed in the case of interaction of RBPs and microRNAs with mRNA targets. RNA structural change is a common mechanism mediating the cooperative/competitive interplay between RBPs and between RBPs and microRNAs. RNA modifications, leading to changes in RNA structure, add a new dimension to cooperative/competitive binding of RBPs to mRNAs, further expanding the RBP regulatory landscape. Therefore, cooperative/competitive interplay between RBPs is a major determinant of the RBP interactome and post-transcriptional regulation of gene expression in cancer cells.

Identification of Antitumor miR-30e-5p Controlled Genes; Diagnostic and Prognostic Biomarkers for Head and Neck Squamous Cell Carcinoma

Analysis of microRNA (miRNA) expression signatures in head and neck squamous cell carcinoma (HNSCC) has revealed that the miR-30 family is frequently downregulated in cancer tissues. The Cancer Genome Atlas (TCGA) database confirms that all members of the miR-30 family (except miR-30c-5p) are downregulated in HNSCC tissues. Moreover, low expression of miR-30e-5p and miR-30c-1-3p significantly predicts shorter survival of HNSCC patients (p = 0.0081 and p = 0.0224, respectively). In this study, we focused on miR-30e-5p to investigate its tumor-suppressive roles and its control of oncogenic genes in HNSCC cells. Transient expression of miR-30e-5p significantly attenuated cancer cell migration and invasive abilities in HNSCC cells. Nine genes (DDIT4, FOXD1, FXR1, FZD2, HMGB3, MINPP1, PAWR, PFN2, and RTN4R) were identified as putative targets of miR-30e-5p control. Their expression levels significantly predicted shorter survival of HNSCC patients (p < 0.05). Among those targets, FOXD1 expression appeared to be an independent factor predicting patient survival according to multivariate Cox regression analysis (p = 0.049). Knockdown assays using siRNAs corresponding to FOXD1 showed that malignant phenotypes (e.g., cell proliferation, migration, and invasive abilities) of HNSCC cells were significantly suppressed. Overexpression of FOXD1 was confirmed by immunostaining of HNSCC clinical specimens. Our miRNA-based approach is an effective strategy for the identification of prognostic markers and therapeutic target molecules in HNSCC. Moreover, these findings led to insights into the molecular pathogenesis of HNSCC.

Rg1 Promotes the Proliferation and Adipogenic Differentiation of Human Adipose-Derived Stem Cells via FXR1/Lnc-GAS5-AS1 Pathway

BACKGROUND

Human adipose-derived stem cells (hASCs) play an important role in regenerative medicine.

OBJECTIVE

Exploring the mechanism of Rg1 in the promotion of the proliferation and adipogenic differentiation of hASCs is important in regenerative medicine research.

METHODS

To observe ginsenoside Rg1 in promoting the proliferation and adipogenic differentiation of hASCs, Rg1 medium at different concentrations was established and tested using the cell counting kit-8 (CCK-8) assay, oil red O staining, alizarin red, and alcian blue. Compared to the control, differentially expressed genes (DEGs) were screened via DEG analysis, which was carried out in the Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses. To explore the relationship among mRNA, long non-coding RNA (lncRNA) and microRNA (miRNA), we constructed a competing endogenous RNA (ceRNA) network.

RESULTS

In this study, Rg1 was observed to promote the proliferation and adipogenic differentiation of hASCs. Additionally, enriched BPs and KEGG pathways may be involved in the promotion process, where FXR1 and Lnc-GAS5-AS1 were found to be regulatory factors. The regulatory network suggested that Rg1 could regulate the adipocytokine signaling pathway and IL-17 signaling pathway via FXR1 and Lnc-GAS5-AS1, which served as the mechanism encompassing the promotion of Rg1 on the proliferation and adipogenic differentiation of hASCs.

CONCLUSION

A comprehensive transcriptional regulatory network related to the promotion ability of Rg1 was constructed, revealing mechanisms regarding Rg1's promotion of the proliferation and adipogenic differentiation of hASCs. The present study provides a theoretical basis for optimizing the function of hASCs.

Prognostic prediction and gene regulation network of EIF2S2 in hepatocellular carcinoma based on data mining

BACKGROUND

Hepatocellular carcinoma (HCC) is a malignant tumor with a high fatality rate, predicting poor prognosis and therapeutic effect. Screening potential prognostic genes in HCC could be a creative way to advance clinical treatment. Eukaryotic translation initiation factor 2 subunit beta (EIF2S2) has reportedly been linked to several tumors, including liver cancer, but the prognostic predictions remain unknown. Therefore, we aimed to clarify the prognostic role and interaction network of EIF2S2 in HCC using bioinformatics data.

METHODS

We screened EIF2S2 using the Oncomine, Ualcan, and TCGA databases. R software was used to analyze the mRNA level and clinicopathological characteristics of hepatocellular carcinoma. Evaluation of the correlations between EIF2S2 and patients' survival was made using the Kaplan-Meier curves and Cox proportional hazards regression model. Then, the influence of EIF2S2 gene mutations on the prognosis of patients was explored by cBioPortal. The protein-protein interaction network of 50 similar genes related to EIF2S2 was implemented by GEPIA2 and Metascape. The LinkedOmics database allowed us to carry out Gene Set Enrichment Analysis. Finally, we constructed the EIF2S2 kinase, miRNA, and transcription factor target networks using GeneMANIA.

RESULTS

EIF2S2 mRNA was overexpressed in HCC and was closely associated with clinicopathological features, including gender, age, race, tumor grade, and stage. There was no correlation between EIF2S2 genetic mutations and prognostic survival. Combining Cox proportional hazards regression model analyses, high-expressed EIF2S2 predicted poor prognosis in HCC patients. Additionally, we screened the top three EIF2S2-related genes (PFDN4, HM13, and SNRPD1), the 50 similar genes, and then constructed a 50-similar-gene protein-protein interaction network identified by the Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways using Metascape. EIF2S2 target networks in HCC were identified in kinase, miRNA, and transcription factor networks, including the mitogen-activated protein kinase 1 (MAPK1), miRNAs (Mir-144), and transcription factors (GGAANCGGAANY_UNKNOWN) using GeneMANIA.

CONCLUSIONS

EIF2S2 plays a crucial role in the gene-regulating network of HCC and may be a potential prognostic marker or therapeutic target for HCC patients.

Identification of miR-199-5p and miR-199-3p Target Genes: Paxillin Facilities Cancer Cell Aggressiveness in Head and Neck Squamous Cell Carcinoma

Our previous study revealed that the miR-199 family (miR-199a-5p/-3p and miR-199b-5p/-3p) acts as tumor-suppressive miRNAs in head and neck squamous cell carcinoma (HNSCC). Furthermore, recent studies have indicated that the passenger strands of miRNAs are involved in cancer pathogenesis. The aim of this study was to identify cancer-promoting genes commonly regulated by miR-199-5p and miR-199-3p in HNSCC cells. Our in silico analysis and luciferase reporter assay identified paxillin (PXN) as a direct target of both miR-199-5p and miR-199-3p in HNSCC cells. Analysis of the cancer genome atlas (TCGA) database showed that expression of PXN significantly predicted a worse prognosis (5-year overall survival rate; p = 0.0283). PXN expression was identified as an independent factor predicting patient survival according to multivariate Cox regression analyses (p = 0.0452). Overexpression of PXN was detected in HNSCC clinical specimens by immunostaining. Functional assays in HNSCC cells showed that knockdown of PXN expression attenuated cancer cell migration and invasion, suggesting that aberrant expression of PXN contributed to HNSCC cell aggressiveness. Our miRNA-based approach will provide new insights into the molecular pathogenesis of HNSCC.

Regulation and different functions of the animal microRNA-induced silencing complex

Among the different types of small RNAs, microRNAs (miRNAs) are key players in controlling gene expression at the mRNA level. To be active, they must associate with an Argonaute protein to form the miRNA induced silencing complex (miRISC) and binds to specific mRNA through complementarity sequences. The miRISC binding to an mRNA can lead to multiple outcomes, the most frequent being inhibition of the translation and/or deadenylation followed by decapping and mRNA decay. In the last years, several studies described different mechanisms modulating miRISC functions in animals. For instance, the regulation of the Argonaute protein through post-translational modifications can change the miRISC gene regulatory activity as well as modulate its binding to proteins, mRNA targets and miRISC stability. Furthermore, the presence of RNA binding proteins and multiple miRISCs at the targeted mRNA 3' untranslated region (3'UTR) can also affect its function through cooperation or competition mechanisms, underlying the importance of the 3'UTR environment in miRNA-mediated repression. Another way to regulate the miRISC function is by modulation of its interactors, forming different types of miRNA silencing complexes that affect gene regulation differently. It is also reported that the subcellular localization of several components of the miRNA pathway can modulate miRISC function, suggesting an important role for vesicular trafficking in the regulation of this essential silencing complex. This article is categorized under: RNA Interactions with Proteins and Other Molecules > RNA-Protein Complexes Regulatory RNAs/RNAi/Riboswitches > RNAi: Mechanisms of Action Regulatory RNAs/RNAi/Riboswitches > Biogenesis of Effector Small RNAs.

MiR-141-3p overexpression suppresses the malignancy of osteosarcoma by targeting FUS to degrade LDHB

Osteosarcoma (OS) is a common malignant bone cancer. Lactate dehydrogenase B (LDHB) has been revealed to act as a tumor promoter in several cancers. It is also revealed to be correlated with poor prognosis in OS, but its molecular mechanism in OS remains veiled. Our work illustrated that LDHB was overexpressed in OS tissues and cells, and it could enhance cell proliferation, migration, and invasion in OS. Subsequently, it was confirmed that fused in sarcoma (FUS) could bind with LDHB to positively regulate the stability of LDHB messenger RNA (mRNA). Besides, FUS expression was revealed to be elevated in OS tissues and positively correlate with LDHB expression. Furthermore, miR-141-3p, down-regulated in OS cells, was identified as the upstream regulator of FUS in OS cells. Besides, miR-141-3p overexpression decreased mRNA and protein levels of FUS and LDHB. More importantly, overexpression of miR-141-3p could impair FUS overexpression-mediated promotion on LDHB mRNA stability and expression. Finally, rescue assays indicated that miR-141-3p regulated OS cells cellular process via regulating LDHB. In sum, miR-141-3p targets FUS to degrade LDHB, thereby attenuating the malignancy of OS cells.

circNRIP1 facilitates keloid progression via FXR1‑mediated upregulation of miR‑503‑3p and miR‑503‑5p

Circular nuclear receptor interacting protein 1 (circNRIP1) is implicated in tumor initiation and progression; however, the underlying mechanism of keloid progression is unclear. To the best of our knowledge, the present study is the first to characterize the contribution of circNRIP1 to keloid progression and evaluate the potential underlying molecular mechanisms using keloid-derived fibroblasts. The expression profile of circNRIP1 was confirmed in keloid tissue. The contribution of circNRIP1 to keloid progression was investigated via loss-of-function assays. Furthermore, the molecular mechanism by which circNRIP1 contributes to pre-microRNA (miR)-503 maturation through blocking Fbxo4-mediated Fragile-X mental retardation 1 (FXR1) ubiquitination was verified. Finally, the biological functions of FXR1, miR-503-3p, and miR-503-5p in keloid-derived fibroblast proliferation, apoptosis and extracellular matrix accumulation were confirmed. circNRIP1 was highly expressed in keloid tissue and keloid-derived fibroblasts. Functional analysis showed that circNRIP1 knockdown successfully blocked the proliferation and expression of extracellular matrix-associated proteins while increasing the rate of apoptosis in keloid-derived fibroblasts. Mechanistically, circNRIP1 maintained FXR1 stability by impeding Fbxo4-mediated FXR1 ubiquitination and degradation. Additionally, FXR1 increased the abundance of miR-503-3p and miR-503-5p by contributing to pre-miR-503 maturation. Knockdown of FXR1, miR-503-3p and miR-503-5p also inhibited proliferation and extracellular matrix accumulation in keloid-derived fibroblasts and increased levels of cell apoptosis. Collectively, the present study confirmed that circNRIP1 contributed to pre-miR-503 maturation via blocking Fbxo4-mediated FXR1 ubiquitination and degradation, which facilitates keloid progression. These results indicate that circNRIP1 has potential as a novel therapeutic target for the control and/or treatment of keloids.

Diagnostic and Therapeutic Implications of microRNAs in Non-Small Cell Lung Cancer

microRNAs (miRNAs), endogenous suppressors of target mRNAs, are deeply involved in every step of non-small cell lung cancer (NSCLC) development, from tumor initiation to progression and metastasis. They play roles in cell proliferation, apoptosis, angiogenesis, epithelial-to-mesenchymal transition, migration, invasion, and metastatic colonization, as well as immunosuppression. Due to their versatility, numerous attempts have been made to use miRNAs for clinical applications. miRNAs can be used as cancer subtype classifiers, diagnostic markers, drug-response predictors, prognostic markers, and therapeutic targets in NSCLC. Many challenges remain ahead of their actual clinical application; however, when achieved, the use of miRNAs in the clinic is expected to enable great progress in the diagnosis and treatment of patients with NSCLC.

Fragile X-related protein family: a double-edged sword in neurodevelopmental disorders and cancer

The fragile X-related (FXR) family proteins FMRP, FXR1, and FXR2 are RNA binding proteins that play a critical role in RNA metabolism, neuronal plasticity, and muscle development. These proteins share significant homology in their protein domains, which are functionally and structurally similar to each other. FXR family members are known to play an essential role in causing fragile X mental retardation syndrome (FXS), the most common genetic form of autism spectrum disorder. Recent advances in our understanding of this family of proteins have occurred in tandem with discoveries of great importance to neurological disorders and cancer biology via the identification of their novel RNA and protein targets. Herein, we review the FXR family of proteins as they pertain to FXS, other mental illnesses, and cancer. We emphasize recent findings and analyses that suggest contrasting functions of this protein family in FXS and tumorigenesis based on their expression patterns in human tissues. Finally, we discuss current gaps in our knowledge regarding the FXR protein family and their role in FXS and cancer and suggest future studies to facilitate bench to bedside translation of the findings.