MicroRNA-181a promotes proliferation and inhibits apoptosis by suppressing CFIm25 in osteosarcoma

Pan-cancer analysis of NUDT21 and its effect on the proliferation of human head and neck squamous cell carcinoma

BACKGROUND

Based on bioinformatics research of NUDT21 in pan-cancer, we aimed to clarify the mechanism of NUDT21 in HHNC by experiment.

METHODS

The correlation between differential expression of NUDT21 in pan-cancer and survival prognosis, genomic instability, tumor stemness, DNA repair, RNA methylation and with immune microenvironment were analyzed by the application of different pan-cancer analysis web databases. In addition, immunohistochemistry staining and genetic detection of NUDT21 in HHNCC tumor tissues by immunohistochemistry and qRT-PCR. Then, through in vitro cell experiments, NUDT21 was knocked down by lentivirus to detect the proliferation, cycle, apoptosis of FaDu and CNE-2Z cells, and finally by PathScan intracellular signaling array reagent to detect the apoptotic protein content.

RESULTS

Based on the pan-cancer analysis, we found that elevated expression of NUDT21 in most cancers was significantly correlated with TMB, MSI, neoantigens and chromosomal ploidy, and in epigenetics, elevated NUDT21 expression was strongly associated with genomic stability, mismatch repair genes, tumor stemness, and RNA methylation. Based on immunosuppressive score, we found that NUDT21 plays an essential role in the immunosuppressive environment by suppressing immune checkpointing effect in most cancers. In addition, using HHNSCC as a study target, PCR and pathological detection of NUDT21 in tumor tissues was significantly increased than that in paracancerous normal tissues. In vitro cellular assays, silencing NUDT21 inhibited proliferation and promoted apoptosis in FaDu and CNE-2Z cells, and blocked the cell cycle in the G2/M phase. Therefore, the experiments confirmed that NUDT21 promotes the proliferation of FaDu by suppressing the expression of apoptotic.

The emerging roles of CFIm25 (NUDT21/CPSF5) in human biology and disease

The mammalian cleavage factor I subunit CFIm25 (NUDT21) binds to the UGUA sequences of precursor RNAs. Traditionally, CFIm25 is known to facilitate 3' end formation of pre-mRNAs resulting in the formation of polyadenylated transcripts. Recent studies suggest that CFIm25 may be involved in the cyclization and hence generation of circular RNAs (circRNAs) that contain UGUA motifs. These circRNAs act as competing endogenous RNAs (ceRNAs) that disrupt the ceRNA-miRNA-mRNA axis. Other emerging roles of CFIm25 include regulating both alternative splicing and alternative polyadenylation (APA). APA generates different sized transcripts that may code for different proteins, or more commonly transcripts that code for the same protein but differ in the length and sequence content of their 3' UTRs (3' UTR-APA). CFIm25 mediated global changes in 3' UTR-APA affect human physiology including spermatogenesis and the determination of cell fate. Deregulation of CFIm25 and changes in 3' UTR-APA have been implicated in several human diseases including cancer. In many cancers, CFIm25 acts as a tumor suppressor. However, there are some cancers where CFIm25 has the opposite effect. Alterations in CFIm25-driven 3' UTR-APA may also play a role in neural dysfunction and fibrosis. CFIm25 mediated 3' UTR-APA changes can be used to generate specific signatures that can be used as potential biomarkers in development and disease. Due to the emerging role of CFIm25 as a regulator of the aforementioned RNA processing events, modulation of CFIm25 levels may be a novel viable therapeutic approach. This article is categorized under: RNA Processing > 3' End Processing RNA in Disease and Development > RNA in Disease.

Micro RNAs and Circular RNAs in Different Forms of Otitis Media

The aim of this comprehensive review was to present the current knowledge on the role of microRNAs (miRNAs) in acute, recurrent, and chronic forms of otitis media. Special attention was focused on cholesteatoma of the middle ear. MicroRNAs modulate gene expression, which, in turn, influences the development and likelihood of the recurrence of acute and aggressive chronic middle ear inflammatory processes. Moreover, this study discusses the modulating role of a specific subgroup of noncoding RNA, circular RNA (circRNA). Recognizing the precise potential pathways and the mechanisms of their function may contribute to a better understanding of the molecular bases of middle ear diseases and identifying novel methods for treating this demanding pathology. Articles published between 2009 and 2022 were used in this analysis. In this review, we provide a complete overview of the latest progress in identifying the role and mechanisms of particular miRNAs and circRNAs in acute, recurrent and chronic forms of otitis media.

Macrophage differentiation is marked by increased abundance of the mRNA 3' end processing machinery, altered poly(A) site usage, and sensitivity to the level of CstF64

Regulation of mRNA polyadenylation is important for response to external signals and differentiation in several cell types, and results in mRNA isoforms that vary in the amount of coding sequence or 3' UTR regulatory elements. However, its role in differentiation of monocytes to macrophages has not been investigated. Macrophages are key effectors of the innate immune system that help control infection and promote tissue-repair. However, overactivity of macrophages contributes to pathogenesis of many diseases. In this study, we show that macrophage differentiation is characterized by shortening and lengthening of mRNAs in relevant cellular pathways. The cleavage/polyadenylation (C/P) proteins increase during differentiation, suggesting a possible mechanism for the observed changes in poly(A) site usage. This was surprising since higher C/P protein levels correlate with higher proliferation rates in other systems, but monocytes stop dividing after induction of differentiation. Depletion of CstF64, a C/P protein and known regulator of polyadenylation efficiency, delayed macrophage marker expression, cell cycle exit, attachment, and acquisition of structural complexity, and impeded shortening of mRNAs with functions relevant to macrophage biology. Conversely, CstF64 overexpression increased use of promoter-proximal poly(A) sites and caused the appearance of differentiated phenotypes in the absence of induction. Our findings indicate that regulation of polyadenylation plays an important role in macrophage differentiation.

The expression of miR-181b, CYLD, CBX-7, BCL2, and p53 in osteosarcoma patients and correlation with clinicopathological factors

Osteosarcoma is a common human malignancy with a high mortality rate worldwide. Recent studies have been focused on understanding the involvement of microRNA (miRNAs) in the pathogenesis of osteosarcoma. Therefore, the present study aimed to measure the expression levels of miR-181a, cylindromatosis (CYLD), chromo box homolog 7 (CBX7), B-cell lymphoma 2 (BCL2), and tumor protein p53 in tumor tissue and adjacent normal tissues in patients with osteosarcoma and its relationship with clinicopathological factors. The expression levels of miR-181a, CYLD, CBX7, BCL2, and p53 were measured in 60 patients with osteosarcoma using quantitative real-time polymerase chain reaction. Finally, we compared the relationship between these gene levels and clinicopathological factors in tumor and healthy tissues. Our results showed that the expression levels of miR-181a, BCL2, and p53 were significantly higher in osteosarcoma tissue in comparison with normal tissues (p < .05). On the contrary, CYLD and CBX7 were downregulated in osteosarcoma tumor tissues compared to adjacent healthy tissues (p < .05). In addition, the expression levels of miR-181a in tumor tissues were strongly correlated with patients' age, tumor size, clinical stage, cancer grade, and lymph node metastasis (p < .05). Our findings highlight new insights into understanding the role of miR-181a in the pathogenesis of osteosarcoma. However, further studies are needed to elucidate miRNA as therapeutic targets for osteosarcoma.

MiR-508-3p promotes proliferation and inhibits apoptosis of middle ear cholesteatoma cells by targeting PTEN/PI3K/AKT pathway

Cholesteatoma of the middle ear is a common disease in otolaryngology, which can lead to serious intracranial and extracranial complications. Recent studies showed that the dysregulation of microRNA may be involved in the formation of middle ear cholesteatoma. This study aimed to explore the regulatory effect of micro ribonucleic acid 508-3p (miR-508-3p) on proliferation and apoptosis of middle ear cholesteatoma cells and excavate its underlying regulatory mechanism. We found miR-508-3p expression was upregulated in tissues and cells of cholesteatoma which was inversely related to the expression of hsa_circ_0000007. Overexpression of miR-508-3p could notably facilitate cholesteatoma cell proliferation. Luciferase reporter assay showed that miR-508-3p bound the 3'-untranslated region of its downstream mRNA PTEN. Gain and loss of functions of miR-508-3p were performed to identify their roles in the biological behaviors of cholesteatoma cells, including proliferation and apoptosis. Rescue assays confirmed that PTEN could reverse the effect of miR-508-3p overexpression on cell proliferation. In a word, this study validated that the development of cholesteatoma may regulated by hsa_circ_0000007/miR-508-3p/ PTEN/ PI3K/Akt axis.

lncRNA TUSC7 inhibits osteosarcoma progression through the miR‑181a/RASSF6 axis

Osteosarcoma (OS) is one of the most aggressive malignancies, accompanied by an elevated incidence and a decreased rate of healing. Recently, several long non-coding RNAs (lncRNAs) have been reported to be involved in OS progression. Although tumor suppressor candidate 7 (TUSC7) was reported as a novel lncRNA, little is known about its biological functions in OS. The present study was designed to explore whether TUSC7 was involved in the pathological development of OS using various methods, including hematoxylin and eosin staining, Cell Counting Kit-8 assay, colony formation assay and Transwell assay. The present study revealed that TUSC7 expression was downregulated in OS tissues and cell lines compared with in normal tissues and cell lines. Functionally, the current results revealed that overexpression of TUSC7 inhibited OS cell proliferation, migration and invasion, while promoting apoptosis in vitro and in vivo. Next, the subcellular distribution of TUSC7 was examined by nuclear/cytoplasmic RNA fractionation and reverse transcription-quantitative PCR. Mechanistic studies revealed that TUSC7 exerted its role by sponging microRNA (miR)-181a in OS cell lines. Ras association domain family member 6 (RASSF6) was confirmed as a target gene of miR-181a, and the expression levels of RASSF6 were negatively regulated by miR-181a. Additionally, the results of rescue experiments suggested that overexpression of miR-181a neutralized the inhibitory effects of TUSC7 overexpression on OS cells. Overall, the present study demonstrated that the tumor suppressor role of TUSC7 in OS progression was mediated through the miR-181a/RASSF6 axis, which may represent a new therapeutic target for OS.

Aggressive Medulloblastoma-Derived Exosomal miRNAs Promote In Vitro Invasion and Migration of Tumor Cells Via Ras/MAPK Pathway

Medulloblastomas (MBs) are currently divided into 4 molecular subgroups: WNT, SHH, Group 3, and Group 4. Among them, Group 3 MB has the worst prognosis, and 40%-50% of Group 3 cases are already metastatic at the time of diagnosis. Emerging evidence indicates that exosomes drive tumor invasion, but very little is known about exosomes in MBs. In this study, we initially discovered that exosomes isolated from Group 3 MB cell lines altered in vitro behaviors of a less invasive SHH MB cell line and yielded a much more aggressive phenotype. RNA-sequencing analysis revealed 7 exosomal miRNAs with markedly different expression levels between the SHH and Group 3 MB cell lines. They were all predicted to be related to the Ras/MAPK pathway according to the Kyoto Encyclopedia of Genes and Genomes data analysis. Increased expression of miR-181a-5p, miR-125b-5p, and let-7b-5p was further confirmed in Group 3 MB cells with real-time PCR and was shown to increase in vitro invasion and migratory abilities of tumor cells through the activation of ERK in Ras/MAPK pathway. Collectively, our findings suggest that exosomal miRNAs have a critical role in MB progression in vitro and might serve as diagnostic biomarkers and therapeutic targets.

Downregulation of CFIm25 amplifies dermal fibrosis through alternative polyadenylation

This study implicates the key regulator of alternative polyadenylation, CFIm25 in dermal fibrosis and in systemic sclerosis (scleroderma) pathogenesis. CFIm25 downregulation promotes the expression of profibrotic factors, exaggerates bleomycin-induced skin fibrosis, while CFIm25 restoration attenuates skin fibrosis.

Systemic sclerosis (SSc; scleroderma) is a multisystem fibrotic disease. The mammalian cleavage factor I 25-kD subunit (CFIm25; encoded by NUDT21) is a key regulator of alternative polyadenylation, and its depletion causes predominantly 3′UTR shortening through loss of stimulation of distal polyadenylation sites. A shortened 3′UTR will often lack microRNA target sites, resulting in increased mRNA translation due to evasion of microRNA-mediated repression. Herein, we report that CFlm25 is downregulated in SSc skin, primary dermal fibroblasts, and two murine models of dermal fibrosis. Knockdown of CFIm25 in normal skin fibroblasts is sufficient to promote the 3′UTR shortening of key TGFβ-regulated fibrotic genes and enhance their protein expression. Moreover, several of these fibrotic transcripts show 3′UTR shortening in SSc skin. Finally, mice with CFIm25 deletion in fibroblasts show exaggerated skin fibrosis upon bleomycin treatment, and CFIm25 restoration attenuates bleomycin-induced skin fibrosis. Overall, our data link this novel RNA-processing mechanism to dermal fibrosis and SSc pathogenesis.

Involved microRNAs in alternative polyadenylation intervene in breast cancer via regulation of cleavage factor "CFIm25"

Cleavage factor “CFIm25”, as a key repressor at proximal poly (A) site, negatively correlates to cell proliferation and tumorigenicity in various cancers. Hence, understanding CFIm25 mechanism of action in breast cancer would be a great benefit. To this aim four steps were designed. First, potential miRNAs that target 3′-UTR of CFIm25 mRNA, retrieved from Targetscan web server. Second, screened miRNAs were profiled in 100 breast cancer and 100 normal adjacent samples. Third, miRNAs that their expression was inversely correlated to the CFIm25, overexpressed in MDA-MB-231 cell line, and their effect on proliferation and migration monitored via MTT and wound healing assays, respectively. Fourth, interaction of miRNAs of interest with 3′-UTR of CFIm25 confirmed via luciferase assay and western blot. Our results indicate that CFIm25 considerably down-regulates in human breast cancer tissue. qRT-PCR assay, luciferase test, and western blotting confirm that CFIm25 itself could be directly regulated by oncomiRs such as miR-23, -24, -27, -135, -182 and -374. Besides, according to MTT and wound healing assays of cell lines, CFIm25 knockdown intensifies cell growth, proliferation and migration. Our results also confirm indirect impact of CFIm25 on regulation of mRNA’s 3′–UTR length, which then control corresponding miRNAs’ action. miRNAs directly control CFIm25 expression level, which then tunes expression of the oncogenes and tumor proliferation. Therefore, regulation of CFIm25 expression level via miRNAs is expected to improve treatment responses in breast cancer.

CFIm25 in Solid Tumors: Current Research Progress

Cleavage factor I m25 is a newly discovered solid tumor-related gene, however, its precise role in cancer pathogenesis has not yet been characterized. Alternative polyadenylation is an RNA-processing mechanism that generates distinct 3′-termini on messenger RNAs, producing messenger RNA isoforms. Different factors influence the initiation and development of this process. As a key factor in alternative polyadenylation, cleavage factor I m25 plays an important role in messenger RNA maturation and cell signal transduction. Moreover, by regulating the process of alternative polyadenylation, it can inhibit the proliferation, invasion, and metastasis of a variety of tumors. Cleavage factor I m25 also acts as an oncogene in select tumors. The present review focuses on the role of cleavage factor I m25 in solid tumors and treatment. Due to the lack of current knowledge regarding the mechanisms of action and regulation of cleavage factor I m25 and alternative polyadenylation, it is necessary to further examine their role in cancer as well as in other diseases.

Emerging Roles of RNA 3'-end Cleavage and Polyadenylation in Pathogenesis, Diagnosis and Therapy of Human Disorders

A crucial feature of gene expression involves RNA processing to produce 3′ ends through a process termed 3′ end cleavage and polyadenylation (CPA). This ensures the nascent RNA molecule can exit the nucleus and be translated to ultimately give rise to a protein which can execute a function. Further, alternative polyadenylation (APA) can produce distinct transcript isoforms, profoundly expanding the complexity of the transcriptome. CPA is carried out by multi-component protein complexes interacting with multiple RNA motifs and is tightly coupled to transcription, other steps of RNA processing, and even epigenetic modifications. CPA and APA contribute to the maintenance of a multitude of diverse physiological processes. It is therefore not surprising that disruptions of CPA and APA can lead to devastating disorders. Here, we review potential CPA and APA mechanisms involving both loss and gain of function that can have tremendous impacts on health and disease. Ultimately we highlight the emerging diagnostic and therapeutic potential CPA and APA offer.

miR‑181b‑p53 negative feedback axis regulates osteosarcoma cell proliferation and invasion

Osteosarcoma (OS) is one of the most common malignant tumors in young adults and as a high distant metastasis rate. The p53 protein, a potent prognostic biomarker for patients with OS, is altered in ~50% of OS cases. p53 was reported to exert its effects through regulating the transcription of microRNAs (miRNAs/miRs) and other genes. In the present study, the expression of miR-181b, a critical OS oncomiR, was shown to be significantly upregulated whereas p53 expression was downregulated within OS tissues and cells; in tissue samples, miR-181b and p53 were negatively correlated. p53 inhibited the transcription of miR-181b via targeting its promoter region, whereas miR-181b bound the TP53 3′-untranslated region (UTR) to inhibit p53 expression. miR-181b silencing considerably increased p53, p21, and epithelial-Cadherin protein levels but decreased Cyclin D1 protein levels in OS cells. In addition, miR-181b inhibition reduced OS cell proliferation and invasion. In contrast, p53 knockdown had the opposite effects on these proteins and OS cell proliferation and invasion. Above all, p53 knockdown significantly attenuated the effects of miR-181b inhibition. Moreover, OS cell xenograft assays further confirmed the roles of the miR-181b/p53 axis in OS growth. In conclusion, miR-181b and p53 are negatively regulated by one another and therefore form a negative feedback axis that regulates the proliferation and invasion abilities of OS cells. Targeting miR-181b to inhibit its abnormal upregulation might be a potent strategy for OS treatment.

NUDT21 suppresses the growth of small cell lung cancer by modulating GLS1 splicing

The mRNA precursor 3'-end modification factor NUDT21 is a major regulator of 3'UTR shortening and an important component of pre-mRNA cleavage and polyadenylation. However, its role in pathologic progress of small cell lung cancer (SCLC) remains unclear. In this study, we observed that NUDT21 expression is downregulated in SCLC tissues. Hypoxia-induced down-regulation of NUDT21 through HIF-1α. NUDT21 shRNA transduction promotes proliferation and inhibits apoptosis of A549 cells. NUDT21 inhibition also promotes tumor growth in a mouse xenograft model. Furthermore, we clarified that HIF-1α mediated NUDT21 downregulation which altered the expression patterns of two isoforms of GLS1, GAC and KGA. These results link the hypoxic tumor environments to aberrant glutamine metabolism which is important for cellular energy in SCLC cells. Therefore, NUDT21 could be considered as a potential target for the treatment of SCLC.

Post-Transcriptional Dysregulation of microRNA and Alternative Polyadenylation in Colorectal Cancer

Background

Colorectal cancer (CRC) is one of the leading causes of cancer death worldwide. microRNAs (miRNAs) repress gene expression by binding to complementary sequences in the 3' untranslated region (3'UTR) of target mRNAs. Alternative polyadenylation (APA) are relevant to the variability of the 3'UTR of mRNA. However, the posttranscriptional dysregulation of miRNAs and APA in CRC are poorly understood.

Method

In this study, we conducted small RNA sequencing to identify differentially expressed miRNAs (DERs) and their target genes. Function analysis on DER-target genes can explain the regulation roles of miRNAs in CRC. The mutual regulation of miRNAs and APA was analyzed by combining miRNA data to 3'UTR alteration using 3' termini of polyadenylated RNAs sequencing (3T-seq) technique, and this was validated using TCGA gene expression data.

Results

Our results showed 64 significant differentially expressed miRNAs (DERs) in CRC patients. Their target genes were related to cell adhesion and transcription regulation and were prevailingly involved in the CRC-related pathway. Integrative analysis of the miRNA and APA profile revealed 16 DERs were correlated with 12 polyadenylation factors, and six of them were significantly differently expressed in CRC. We also found four DERs that lost binding sites due to APA and showed a positive correlation between the miRNA and gene expression.

Conclusion

Our study found that miRNAs regulated APA by modulating key polyadenylation factors, and several miRNAs lost their suppression on mRNA due to APA. Associating this with gene expression may provide some important clues for a deeper study of posttranscriptional cellular regulation and biomarker research in CRC. Our data provided the first evidence that the interaction between miRNAs and APA associated with gene expression could serve as biomarkers for CRC, suggesting that hsa-miR-133a-3p and MLEC, hsa-miR-145-5p and SET, hsa-miR-1-3p and PPIA, and hsa-miR-378d and YY1 might be novel and potential biomarkers in improving the diagnosis of CRC.

The Butterfly Effect of RNA Alterations on Transcriptomic Equilibrium

: Post-transcriptional regulation plays a key role in modulating gene expression, and the perturbation of transcriptomic equilibrium has been shown to drive the development of multiple diseases including cancer. Recent studies have revealed the existence of multiple post-transcriptional processes that coordinatively regulate the expression and function of each RNA transcript. In this review, we summarize the latest research describing various mechanisms by which small alterations in RNA processing or function can potentially reshape the transcriptomic landscape, and the impact that this may have on cancer development.

miRNA signatures in childhood sarcomas and their clinical implications

Progresses in multimodal treatments have significantly improved the outcomes for childhood cancer. Nonetheless, for about one-third of patients with Ewing sarcoma, rhabdomyosarcoma, or osteosarcoma steady remission has remained intangible. Thus, new biomarkers to improve early diagnosis and the development of precision-targeted medicine remain imperative. Over the last decade, remarkable progress has been made in the basic understanding of miRNAs function and in interpreting the contribution of their dysregulation to cancer development and progression. On this basis, this review focuses on what has been learned about the pivotal roles of miRNAs in the regulation of key genes implicated in childhood sarcomas.

Alternative polyadenylation of mRNA and its role in cancer

Alternative polyadenylation (APA) is a molecular process that generates diversity at the 3′ end of RNA polymerase II transcripts from over 60% of human genes. APA is derived from the existence of multiple polyadenylation signals (PAS) within the same transcript, and results in the differential inclusion of sequence information at the 3′ end. While APA can occur between two PASs allowing for generation of transcripts with distinct coding potential from a single gene, most APA occurs within the untranslated region (3′UTR) and changes the length and content of these non-coding sequences. APA within the 3′UTR can have tremendous impact on its regulatory potential of the mRNA through a variety of mechanisms, and indeed this layer of gene expression regulation has profound impact on processes vital to cell growth and development. Recent studies have particularly highlighted the importance of APA dysregulation in cancer onset and progression. Here, we review the current knowledge of APA and its impacts on mRNA stability, translation, localization and protein localization. We also discuss the implications of APA dysregulation in cancer research and therapy.

Hypermethylated long noncoding RNA MEG3 promotes the progression of gastric cancer

This study aims to explore the expression and degree of methylation of lncRNA MEG3 in gastric cancer tissues and to analyze its effect on the migration and proliferation of gastric cancer patients and the mechanism by which this occurs. The targeting relationship between MEG3, miR-181a-5p and ATP4B was detected through molecular biology experiments. Wound healing, transwell, colony formation and flow cytometry assays were used to analyze the effects of lncRNA MEG3 and methylation on tumor cell migration, invasion, proliferation and apoptosis. In addition, a tumor xenotransplantation model was established to study the influence of MEG3 on tumor growth in vivo. Bioinformatics analysis showed that lncRNA MEG3 and ATP4B were downregulated in gastric cancer tissues compared with normal tissues. Bioinformatics predicted that ATP4B might be regulated by targeting miR-181a-5p. The overexpression of MEG3 and the application of 5-Aza treatment inhibited the migration, invasion and proliferation of MGC-803 cells and promoted apoptosis. In gastric cancer tissues, MEG3 is hypermethylated to decrease expression. Once the expression of MEG3 is restored or methylation is inhibited, tumor growth can be inhibited both in vivo and in vitro. This finding could be utilized as a clinical reference for gastric cancer treatment in the future.

CFIm25 and alternative polyadenylation: Conflicting roles in cancer

Alternative polyadenylation (APA) is now widely recognized to regulate gene expression. APA is an RNA-processing mechanism that generates distinct 3' termini on mRNAs, producing mRNA isoforms. Different factors influence the initiation and development of this process. CFIm25 (among others) is a cleavage and polyadenylation factor that plays a key role in the regulation of APA. Shortening of the 3'UTRs on mRNAs leads to enhanced cellular proliferation and tumorigenicity. One reason may be the up-regulation of growth promoting factors, such as Cyclin D1. Different studies have reported a dual role of CFIm25 in cancer (both oncogenic and tumor suppressor). microRNAs (miRNAs) may be involved in CFIm25 function as well as competing endogenous RNAs (ceRNAs). The present review focuses on the role of CFIm25 in cancer, cancer treatment, and possible involvement in other human diseases. We highlight the involvement of miRNAs and ceRNAs in the function of CFIm25 to affect gene expression. The lack of understanding of the mechanisms and regulation of CFIm25 and APA has underscored the need for further research regarding their role in cancer and other diseases.

MicroRNA-181a Functions as an Oncogene in Gastric Cancer by Targeting Caprin-1

MicroRNA-181a (miRNA-181a) is a multifaceted miRNA implicated in various cellular processes, particularly in cell fate determination and cellular invasion. It is frequently expressed aberrantly in human tumors and shows opposing functions in different types of cancers. In this study, we found that miRNA-181a is overexpressed in Gastric cancer (GC) tissues. Clinical and pathological analyses revealed that the expression of miRNA-181a is correlated with tumor size, lymph node metastasis, distant metastasis, and TNM stage. Kaplan-Meier analysis indicated that overexpression of miRNA-181a is associated with poor overall survival of patients with GC. Moreover, miRNA-181a is overexpressed in GC cells, and downregulation of miRNA-181a induced cell apoptosis and suppressed the proliferation, invasion, and metastasis of GC cells both in vitro and in vivo. Target prediction and luciferase reporter assay showed that caprin-1 was a direct target of miRNA-181a. Downregulation of caprin-1 expression resulted in a converse change with miRNA-181a in GC. Spearman’s correlation test confirmed that the expression of miRNA-181a expression was inversely correlated with that of caprin-1 in GC cells. Furthermore, the expression of caprin-1 increased after downregulation of miRNA-181a in the GC cells. Caprin-1 siRNA can rescue the oncogenic effect of miRNA-181a on GC cell proliferation, apoptosis, migration, and invasion. These findings suggest that miRNA-181a directly inhibits caprin-1 and promotes GC development. miRNA-181a could be a target for anticancer drug development.

Knockdown of NUDT21 inhibits proliferation and promotes apoptosis of human K562 leukemia cells through ERK pathway

Background

NUDT21 is a mammalian precursor mRNA(pre-mRNA) 3’ end processing factor and plays an important role in the selection of poly(A) sites in 3’-untranslated region (3’-UTR). NUDT21 links alternative polyadenylation with regulation of glioblastoma and osteosarcoma progression and is found to be related to drug resistance in childhood acute leukemia. However, the effect of NUDT21 on leukemia cells and the underlying mechanism are unknown.

Methods

We knocked down NUDT21 in K562 cells and applied qRT-PCR and western blotting to quantitate the mRNA and protein expression. Cell proliferating and apoptosis were investigated subsequently by flow cytometry, BrdU, Caspase3/7. RNA microarray and intracellular signaling array were used to determine the important cell signaling pathways.

Results

We clarified that the mRNA expression levels of NUDT21 are higher in primary chronic myelocytic leukemia patients and K562 leukemic cells compared with healthy controls and PBMCs. Downregulation of NUDT21 expression in K562 cells inhibits proliferation and promotes apoptosis. Screening by mRNA chip and intracellular signaling array, we found that MAPK/ERK pathway represented the main molecular mechanism underlying the effects of NUDT21 knockdown in K562 cells.

Conclusion

NUDT21 played an important role in promoting proliferation and inhibiting apoptosis in leukemia K562 cells. The underlying mechanisms involved the modulation of PTEN and a set of downstream molecules including ERK1/2.

Impact statement

The present work shows that the expression of NUDT21 was upregulated in chronic myelocytic leukemia and K562 cells. Silencing NUDT21 inhibited the proliferation and promoted the apoptosis of K562 cells. Subsequent experiments confirmed that NUDT21 promoted K562 proliferation through regulating the expression of p-ERK. Our findings may provide insights into the molecular mechanism underlying the effects of NUDT21 on leukemia cells and a novel strategy for the treatment of leukemia.

Unique MicroRNAs Signature of Lymphocyte of Yang and Yin Syndromes in Acute Ischemic Stroke Patients

OBJECTIVE

To identify the differentially expressed microRNAs (miRNAs) profiles of yang and yin syndromes in patients with acute ischemic stroke, and to provide the molecular basis of the classification of these two syndrome types in acute ischemic stroke patients.

METHODS

A microarray assay was performed to assess the expression pattern of miRNAs in the lymphocyte of acute ischemic stroke patients. Target genes for the deregulated miRNAs were predicated using the online bioinformatic algorithms and functional annotation via Kyoto encyclopedia of genes and genomes pathway analysis for miRNAs predicted targets was carried out. Based on the predicted target genes of differentially expressed miRNAs, the miRNA-gene-network and miRNA-pathway-network were constructed.

RESULTS

Yang score based on tongue texture, urine, dejecta, and appearance, etc. showed that clinical symptoms were distinct between yang and yin syndromes. There were significantly higher total leukocyte number and lower total protein level in patients with yang syndrome compared with those in patients with yin syndrome (P<0.05). Comprehensive miRNA analysis identified 36 unique down-regulated miRNAs in yang syndrome group, and 20 unique down-regulated and 2 unique up-regulated miRNAs in yin syndrome group. The key regulatory miRNAs, gene, and pathways in the yang syndrome were hsa-miR-93-5p and -320b, enabled homolog, the metabolic pathways and mitogen-activated protein kinase signaling pathways, respectively, while those in the yin syndrome were hsa-miR-424-5p and -106b-5p, CNOT4, hepatitis B and pathways in cancer, respectively.

CONCLUSION

These results offered insight into the molecular basis underlying the different pathogenesis of yang or yin syndrome, providing clues for the individualized therapeutic strategies of acute ischemic stroke.

Long non-coding RNA CASC2 inhibits tumorigenesis via the miR-181a/PLXNC1 axis in melanoma

Melanoma is the most malignant and aggressive form of skin carcinoma originating in the pigment-producing melanocytes. In this study, to further investigate the molecular mechanisms of the development and progression of melanoma, we explored the impacts of long non-coding RNA (lncRNA) CASC2 on melanoma cell functions. Microarray analysis was carried out to identify the expression of lncRNA CASC2 in melanoma cells. MiR-181a was predicted as a sponging target of CASC2 by miRcode, while the 3'-UTR of Plexin C1 (PLXNC1) was a potential target of miR-181a according to the TargetScan database. The correlation among CASC2, miR-181a, and PLXNC1 was verified by dual luciferase reporter assay and qRT-PCR. After manipulation of CASC2, miR-181a and PLXNC1 expression with transfection in A375 and M14 cells, cell viability, apoptosis, and invasive ability were evaluated using CCK-8, flow cytometry and Transwell assays, respectively. A low expression of CASC2 was detected in melanoma tissues and cells. Dual luciferase reporting assay confirmed that miR-181a targeted the 3'-UTR of PLXNC1. Furthermore, CASC2 could efficiently sponge miR-181a, thereby facilitating the expression of PLXNC1. Up-regulation of CASC2 suppressed the cell proliferation and invasion, but induced the apoptosis of melanoma cells. Our results demonstrated that lncRNA CASC2 can promote PLXNC1 expression by sponging miR-181a, thereby inhibiting the proliferation and invasion of melanoma cells, indicating that lncRNA CASC2 functions via the miR-181a/PLXNC1 axis in melanoma.

Human Aging and Cancer: Role of miRNA in Tumor Microenvironment

Human aging is an inevitable and complex phenomenon characterized by a progressive, gradual degradation of physiological and cellular processes that leads from vulnerability to death. Mammalian somatic cells display limited proliferative properties in vitro that results in a process of permanent cell cycle arrest commonly known as senescence. Events leading to cellular senescence are complex but may be due to the increase in tumor suppressor genes, caused by lifetime somatic mutations. Cumulative mutation leaves an imprint on the genome of the cell, an important risk factor for the occurrence of cancer. Adults over the age of 65+ are vulnerable to age related diseases such as cancers but such changes may begin at middle age. MicroRNAs (miRNAs), which are small non-coding RNA, can regulate cancer progression, recurrence and metastasis. This chapter discusses the role of miRNA in tumor microenvironment, consequent to aging.

Downregulation of lncRNA CASC2 facilitates osteosarcoma growth and invasion through miR-181a

OBJECTIVES

Long non-coding RNA cancer susceptibility candidate 2 (CASC2) is a novel lncRNA and has been indicated as playing tumour suppressor gene in several tumours. However, the role of CASC2 in osteosarcoma is still uncovered.

MATERIALS AND METHODS

The CASC2 and miR-181a expressions were measured via qRT-PCR. CCK-8 assay and colony formation assay were performed to determine the cell growth, and transwell assay was performed to assess the cell invasion.

RESULTS

We showed that CASC2 expression was downregulated in osteosarcoma samples and cell lines. Moreover, we showed that downregulated expression of CASC2 was correlated with advanced TNM stage. Furthermore, overexpression of CASC2 inhibited osteosarcoma cell proliferation, colony formation, and invasion. In addition, we indicated that ectopic expression of CASC2 suppressed miR-181a expression and enhanced the expression of Ras association domain family member 6 (RASSF6), PTEN and ATM in osteosarcoma cell, which were the direct target gene of miR-181a. Moreover, we indicated that RASSF6 expression was downregulated in osteosarcoma samples and cell lines and downregulated expression of RASSF6 was correlated with advanced TNM stage. We found that the expression of RASSF6 was positively correlated with the expression of CASC2 in osteosarcoma tissues. Ectopic expression of CASC2 suppressed the osteosarcoma cell proliferation, colony formation and invasion through regulating RASSF6 expression.

CONCLUSIONS

Our data illuminated that CASC2 acted as a tumour suppressor in osteosarcoma progression.

NUDT21 regulates 3'-UTR length and microRNA-mediated gene silencing in hepatocellular carcinoma

Recent studies have shown that several microRNAs (miRNAs) are involved in hepatocellular carcinoma (HCC) tumorigenesis and metastasis; however, the mechanisms responsible for the differences in the functions of these miRNAs in liver cancer remain a mystery. In our previous study, we identified NUDT21 as an interaction partner of argonaute 2 (AGO2). NUDT21 has been reported to be involved in alternative polyadenylation (APA); thus, the interaction between NUDT21 and AGO2 may be a key component of the crosstalk between APA and miRNA-mediated gene silencing in HCC. Our data showed that NUDT21 expression was decreased in HCC. Moreover, our results showed that NUDT21 co-localized with AGO2 in P/GW bodies in normal liver cells; however, this co-localization was diminished in cancer cells. Functional studies showed that NUDT21 elongated the 3'-UTR of mRNA and enhanced the efficiency of miRNA-mediated gene silencing by increasing the efficiency of AGO2-mRNA binding, which played an important role in cell proliferation. In summary, loss of NUDT21 shortened the 3'-UTR of various oncogenes in HCC cells. The shorter 3'-UTR contained less miRNA binding sites, which enabled the oncogenes to evade miRNA regulation and become overexpressed in HCC, leading to unregulated cancer cell proliferation.

Heat shock transcription factor 1 promotes the proliferation, migration and invasion of osteosarcoma cells

OBJECTIVES

Osteosarcoma is the most commonly diagnosed primary malignancy of bone and its overall survival rate is still very low. The molecular mechanisms underlying the progression of osteosarcoma have not been clearly illuminated. Heat shock transcription factor 1 (HSF1) is a key regulator of the heat shock response and also plays important roles in many cancers, but its function in osteosarcoma remains unexplored.

MATERIALS AND METHODS

In this study, the proliferation of osteosarcoma cells was determined by Cell Counting Kit-8 assays and colony formation assays. Transwell assays were used to demonstrate the migration and invasion abilities of osteosarcoma cells. A tumour formation assay in a nude mouse model was performed to assess the effect of HSF1 on osteosarcoma cell growth in vivo. The protein levels of HSF1 were analysed with immunohistochemical staining in samples from osteosarcoma patients.

RESULTS

We demonstrated that knockdown of HSF1 reduced the proliferation, migration and invasion of osteosarcoma cells, while overexpression of HSF1 promoted the proliferation, migration and invasion of osteosarcoma cells. Furthermore, HSF1 promoted the proliferation of osteosarcoma cells in vivo. In addition, high levels of HSF1 were associated with a poor prognosis in osteosarcoma.

CONCLUSIONS

These data highlight an important role of HSF1 in proliferation, migration and invasion of osteosarcoma cells. Moreover, the expression of HSF1 was associated with prognosis in osteosarcoma.