Genome-wide profiling reveals alternative polyadenylation of mRNA in human non-small cell lung cancer.

BACKGROUND: Lung cancer is the second most common cancer with an extremely poor overall survival rate. Post-transcriptional regulation of gene expression play many important roles in human cancer, and one of the potential mechanisms underlying this is alternative mRNA maturation at its 3' untranslated regions (3'-UTRs). METHODS: Cancer tissues and paired adjacent normal lung tissues from 26 patients diagnosed with non-small cell lung cancer (NSCLC) were analyzed by in vitro transcription-sequencing alternative polyadenylation sites (IVT-SAPAS). 41,773,101 reads in average were obtained from each paired sample. A potential regulation of Cleavage Stimulation Factor Subunit 2 (CSTF2) on 3'UTR length of genes was tested in H460 cells. RESULTS: 1439 (10.26%) genes showed up-regulated expression and 1364 (9.72%) genes showed down-regulated expression in lung cancer tissue versus normal lung tissue, and shorten 3'UTR in cancer tissue was detected in cancer tissues collected from 96.2% (25/26) patients, indicating lung cancer tend to have shortened 3'UTRs of these identified genes. KEGG analysis showed 1855 genes with shorten 3'UTR were enriched in mTOR signaling, ubiquitin mediated proteolysis and RNA degradation. Knocking down CSTF2 expression in H460 cells results in 3'UTR elongation of genes that was identified to be with shortened length in cancer tissues. CONCLUSION: Alternative polyadenylation (APA) site-switching of 3'UTRs is prevalent in NSCLC, and CSTF2 may serve as an oncogene regulates the 3'UTR length of cancer related genes in NSCLC.

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 RNA-binding protein CSTF2 regulates BAD to inhibit apoptosis in glioblastoma.

RNA-binding proteins (RBP) regulate several aspects of co- and post-transcriptional gene expression in cancer cells. CSTF2 is involved in the expression of many cellular mRNAs and involved in the 3'-end cleavage and polyadenylation of pre-mRNAs to terminate transcription. However, the role of CSTF2 in human glioblastoma (GBM) and the underlying mechanisms remain unclear. In the present study, CSTF2 was found to be upregulated in GBM, and its high expression predicted poor prognosis. Knockdown CSTF2 induced GBM cell apoptosis both in vitro and in vivo. Specific mechanism studies showed that CSTF2 unstabilized the mRNA of the BAD protein by shortening its 3' UTR. Additionally, an increase in the expression level of CSTF2 decreased the expression level of BAD. In conclusion, CSTF2 binds to the mRNA of the BAD protein to shorten its 3'UTR, which negatively affects the BAD mediated apoptosis and promotes GBM cell survival.

The role of CSTF2 in cancer: from technology to clinical application.

A protein called cleavage-stimulating factor subunit 2 (CSTF2, additionally called CSTF-64) binds RNA and is needed for the cleavage and polyadenylation of mRNA. CSTF2 is an important component subunit of the cleavage stimulating factor (CSTF), which is located on the X chromosome and encodes 557 amino acids. There is compelling evidence linking elevated CSTF2 expression to the pathological advancement of cancer and on its impact on the clinical aspects of the disease. The progression of cancers, including hepatocellular carcinoma, melanoma, prostate cancer, breast cancer, and pancreatic cancer, is correlated with the upregulation of CSTF2 expression. This review provides a fresh perspective on the investigation of the associations between CSTF2 and various malignancies and highlights current studies on the regulation of CSTF2. In particular, the mechanism of action and potential clinical applications of CSTF2 in cancer suggest that CSTF2 can serve as a new biomarker and individualized treatment target for a variety of cancer types.

Detection of CSTF2 by nano fluorescent probe and its correlation with malignant biological characteristics in liver cancer.

To develop a novel nano DNA fluorescent probe for in situ detection of CSTF2 in liver cancer (LC) and study its correlation with the development of LC, we developed nano-TiO2-DNA fluorescent probe which can bind with CSTF2 in LC samples with high efficiency. The detection process of CSTF2 did not involve the use PCR technology, and the concentration of CSTF2 can be directly observed by fluorescence intensity. This probe exhibited excellent physicochemical properties in ethyl alcohol at -20°C and could directly and selectively permeate into Hep-3B cells. By using CSTF2 Nano-TiO2-DNA probe, we found that the CSTF2 level increased greatly in LC tissue and cells, and high CSTF2 level was closely associated with high levels of tumor markers and poor prognosis in LC patients. After transfection, CSTF2 was overexpressed or silenced in Hep-3B cells, and we find that high CSTF2 level effectively increased the activity and invasion of Hep-3B cells and reduced their apoptosis. Furthermore, high CSTF2 level significantly increased the tumor volume and weight in mice models by activating PI3K/AKT/mTOR signal pathway. Therefore, CSTF2 can serve as an early biomarker of LC and a novel potential target for its treatment.

CSTF2T up-regulates IGHG1 by binding to ZEB1 to promote melanoma cell proliferation, migration, and invasion.

OBJECTIVES: Melanoma progression involves multiple molecular pathways. In this study, we explored the effect of immunoglobulin heavy constant gamma 1 (IGHG1) on melanoma progression. METHODS: IGHG1, zinc finger E-box binding homeobox 1 (ZEB1), and cleavage stimulation factor subunit 2 tau variant (CSTF2T) expression levels were measured by quantitative reverse-transcription polymerase chain reaction and western blot. BALB/c nude mice were subcutaneously injected with A375 cells to develop a transplantation tumor model, 4 weeks after which the tumor tissues were collected. Cell proliferation, cell invasion, and cell migration of A375 and SK-MEL-28 cells were measured after gain- and loss-of-function of IGHG1, ZEB1, and CSTF2T. Binding of ZEB1 to the IGHG1 promoter was assayed by chromatin immunoprecipitation and dual-luciferase reporter gene assays, while binding of CSTF2T to ZEB1 mRNA was investigated by RNA immunoprecipitation and RNA pull-down assays. RESULTS: IGHG1, ZEB1, and CSTF2T were all highly expressed in human melanoma cell lines. In A375 and SK-MEL-28 cells, ZEB1 binds directly to the IGHG1 promoter. ZEB1 silencing reduced IGHG1 expression and melanoma cell proliferative, invasive, and migratory properties, and these cellular effects were nullified by overexpression of IGHG1. CSTF2T binds directly to ZEB1 mRNA. Silencing of CSTF2T diminished ZEB1 expression and restrained melanoma cell proliferative, invasive, and migratory capabilities. The impacts of CSTF2T silencing on melanoma cells were counteracted by concomitant overexpression of ZEB1. CSTF2T knockdown reduced tumor volume and weight in nude mice. CONCLUSIONS: The CSTF2T-ZEB1-IGHG1 axis promotes melanoma cell proliferation and invasion.

Hypoxia-associated genes predicting future risk of myocardial infarction: a GEO database-based study.

Background: Patients with unstable angina (UA) are prone to myocardial infarction (MI) after an attack, yet the altered molecular expression profile therein remains unclear. The current work aims to identify the characteristic hypoxia-related genes associated with UA/MI and to develop a predictive model of hypoxia-related genes for the progression of UA to MI. Methods and results: Gene expression profiles were obtained from the GEO database. Then, differential expression analysis and the WGCNA method were performed to select characteristic genes related to hypoxia. Subsequently, all 10 hypoxia-related genes were screened using the Lasso regression model and a classification model was established. The area under the ROC curve of 1 shows its excellent classification performance and is confirmed on the validation set. In parallel, we construct a nomogram based on these genes, showing the risk of MI in patients with UA. Patients with UA and MI had their immunological status determined using CIBERSORT. These 10 genes were primarily linked to B cells and some inflammatory cells, according to correlation analysis. Conclusion: Overall, GWAS identified that the CSTF2F UA/MI risk gene promotes atherosclerosis, which provides the basis for the design of innovative cardiovascular drugs by targeting CSTF2F.

CSTF2T facilitates pancreatic adenocarcinoma growth and metastasis by elevating H3K4Me1 methylation of CALB2 via ASH2L.

Pancreatic adenocarcinoma (PAAD) is a major cause of mortality related to cancer worldwide. This paper dissected the functions of the CSTF2T/ASH2L/CALB2 axis in PAAD progression. CALB2 expression was assessed in PAAD tissues and cells using RT-qPCR and western blot. Subsequent to gain- and loss-of-function experiments in PAAD cells, cell apoptosis, invasion, proliferation, and migration were examined using flow cytometry, Transwell, CCK-8, and Scratch assays. Additionally, the expression of proliferation markers and apoptotic and metastasis- and invasion-related proteins was measured using western blot. The relationship among CALB2, KMT2D, ASH2L, H3K4Me1, and CSTF2T was evaluated using ChIP, RNA pull-down, RIP, and Co-IP assays. A nude mouse transplantation tumor model was established, with observation of tumor growth and metastasis. CALB2 expression was high in PAAD tissues and cells. Mechanistically, KMT2D was enriched in the CALB2 promoter, and CSTF2T bound to and upregulated ASH2L as a RNA binding protein, which was a core component of the KMT2D complex to enhance CALB2 expression through H3K4Me1 upregulation. CALB2 knockdown diminished the viability, invasion, and migration but elevated the apoptosis of PAAD cells. Likewise, CSTF2T knockdown suppressed the growth and metastasis of PAAD cells and transplanted tumors in nude mice, which was counteracted by further CALB2 overexpression. CSTF2T knockdown blocked the ASH2L/CALB2 axis to protect against PAAD growth and metastasis.

CSTF2 Promotes Hepatocarcinogenesis and Hepatocellular Carcinoma Progression via Aerobic Glycolysis.

Background: The shortening of 3' untranslated regions (3'UTRs) of messenger RNAs(mRNAs) by alternative polyadenylation (APA) is an important mechanism for oncogene activation. Cleavage stimulation factor 2 (CSTF2), an important regulator of APA, has been reported to have a tumorigenic function in urothelial carcinoma of the bladder and lung cancers. However, the tumor-promoting role of CSTF2 in hepatocellular carcinoma (HCC) and its underlying molecular mechanism remains unclear. Methods: Multiple databases were used to analyze the expression level and prognostic value of CSTF2 in HCC. Function enrichment analysis was used to investigate the molecular mechanism of CSTF2 for the occurrence and development of HCC. The biological function in HCC cell lines in vitro was determined by CCK8, colony formation, Transwell migration, and invasion assay. Moreover, the tumorigenic function of CSTF2 in vivo was measured by a subcutaneous tumor formation or injecting four plasmids into a mouse tail vein within 5-7 s in an immunocompetent HCC mouse model. In addition, aerobic glycolysis in HCC cells was determined by measuring the extracellular acid rate (ECAR) and extracellular glucose and lactate levels. Results: Bioinformatics analysis revealed that CSTF2 was overexpressed in HCC tissues. The high expression of CSTF2 was correlated with a poor prognosis and high histological grades. CSTF2 knockout inhibited the proliferation, migration, and invasion of HCC cells. In addition, CSTF2 knockout HCC cells failed to form tumors by a subcutaneous graft experiment. Furthermore, endogenous CSTF2 knockout attenuated hepatocarcinogenesis in an immunocompetent HCC mouse model. Function enrichment analysis suggested that the high expression of CSTF2 was associated with enhanced glycolysis. Moreover, we found that CSTF2 knockout reduced the level of the short 3' UTR isoform of hexokinase 2 and increased its level of long 3'UTR. Furthermore, CSTF2 knockout inhibited ECAR levels, glucose uptake, and lactate production. Conclusion: Our results indicated that CSTF2 is highly expressed in HCC and is correlated with a poor prognosis and high histological grade. The knockout of CSTF2 inhibits the tumorigenesis and procession of HCC both in vitro and in vivo. Moreover, CSTF2 is associated with enhanced glycolysis. Therefore, this study suggests that CSTF2 might be a new prognostic biomarker and therapeutic target for HCC.

CSTF2 Acts as a Prognostic Marker Correlated with Immune Infiltration in Hepatocellular Carcinoma.

Background: Cleavage stimulation factor 2 (CSTF2) encodes a nuclear protein that is implicated in the development of various cancers. However, the role of CSTF2 in hepatocellular carcinoma (HCC) has not been understood. This study aims to explore the function of CSTF2 in HCC. Methods: The expression, diagnostic capability, prognostic value, and immune cell effect of CSTF2 in HCC were explored using various databases. The expression level of CSTF2 were validated in our cell lines. The effect of CSTF2 on hepatocarcinogenesis was explored by CSTF2 silencing. Results: CSTF2 expression was significantly elevated in HCC and correlated with multiple clinicopathological characteristics. CSTF2 exhibited good diagnostic capability in discriminating HCC samples from nontumorous samples. High CSTF2 expression was significantly related to poor overall survival. Univariate and multivariate Cox regression analyses suggested that CSTF2 expression was an independent risk factor for HCC. These results were validated in ICGC cohorts. In addition, the nomogram based on CSTF2 showed better predictive performance than the AJCC staging system in TCGA and ICGC cohorts. Functional enrichment analysis revealed that CSTF2-related genes were involved in DNA/RNA processing and the cell cycle. In addition, we found that CSTF2 expression was closely related to the levels of various infiltrating immune cells, especially neutrophils. Moreover, some immune checkpoints had positive relationships with CSTF2 expression. CSTF2 silencing inhibited proliferation, invasion and migration, and promoted apoptosis in HepG2 cells. Western blotting analysis revealed that CSTF2 silencing inactivated the Wnt/ß-catenin signaling pathway. Conclusion: High CSTF2 expression not only correlates with unfavorable outcomes but also affects immune cell infiltration and immune checkpoint expression in HCC. CSTF2 silencing can alleviate the malignant phenotypes of hepatic cancer cell by inactivating the Wnt/ß-catenin signaling pathway. These results indicate that CSTF2 can serve as a promising prognostic marker and therapeutic target for HCC patients.

Cleavage stimulation factor 2 promotes malignant progression of liver hepatocellular carcinoma by activating phosphatidylinositol 3'-kinase/protein kinase B/mammalian target of rapamycin pathway.

Liver hepatocellular carcinoma (LIHC) is the most common type, comprising 75-85% of all liver malignancies. We investigated the roles of cleavage stimulation factor 2 (CSTF2) in LIHC and explored the underlying mechanisms. CSTF2 expression and its association with LIHC patient survival probability were analyzed with The Cancer Genome Atlas. CSTF2 expression in LIHC cells was assessed using western blot and quantitative real-time PCR. Alterations in CSTF2 expression were induced by cell transfection. Cell colony formation, apoptosis, proliferation, invasion, and migration were assessed using colony formation, flow cytometry, 5-ethynyl-2'-deoxyuridine, and transwell assays. Pathway enrichment analysis was performed using gene set enrichment analysis (GSEA). The expression of apoptosis-, metastasis-, and pathway-associated factors was determined via western blot. The pathway rescue assay was further performed using 740Y-P or Wortmannin. CSTF2 upregulation was observed in LIHC tissues and cells. Patients with high CSTF2 expression had a lower probability of overall survival. CSTF2 overexpression enhanced colony formation, proliferation, invasion and migration, while repressing apoptosis in LIHC cells. GSEA revealed that CSTF2 was mainly enriched in the phosphatidylinositol 3'-kinase/protein kinase B/mammalian target of rapamycin (PI3K/AKT/mTOR) pathway. Western blot analysis proved that CSTF2 overexpression activated this pathway. CSTF2 knockdown yielded the opposite effects. 740Y-P, a PI3K activator, reversed the CSTF2 knockdown-triggered effects on cell proliferation, apoptosis, invasion, and migration. Moreover, Wortmannin, a PI3K inhibitor, also reversed the CSTF2 overexpression-induced effects on cell proliferation, apoptosis, invasion, and migration. These results indicated that CSTF2 overexpression might exacerbate the malignant phenotypes of LIHC cells via activation of PI3K/AKT/mTOR pathway.

Alternative polyadenylation writer CSTF2 forms a positive loop with FGF2 to promote tubular epithelial-mesenchymal transition and renal fibrosis.

Effective therapies for renal fibrosis, the common endpoint for most kidney diseases, are lacking. We previously reported that alternative polyadenylation (APA) drives transition from acute kidney injury to chronic kidney disease, suggesting a potential role for APA in renal fibrogenesis. Here, we found that among canonical APA writers, CSTF2 expression was upregulated in tubular epithelial cells (TEC) of fibrotic kidneys. CSTF2 was also identified as a TGF-ß-inducible pro-fibrotic gene. Further analysis revealed that CSTF2 promoted epithelial-mesenchymal transition (EMT) and extracellular matrix (ECM) overproduction in TEC by inducing 3'UTR shortening and upregulation of the expression of basic fibroblast growth factor 2 (FGF2). Additionally, 3'UTR shortening stabilised FGF2 mRNA through miRNA evasion. Interestingly, FGF2 enhanced CSTF2 expression, leading to the forming of a CSTF2-FGF2 positive loop in TEC. Furthermore, CSTF2 knockdown alleviated unilateral ureteral obstruction-induced renal fibrosis in vivo. Finally, we developed a CSTF2-targeted antisense oligonucleotide (ASO) and validated its effectiveness in vitro. These results indicate that the expression of the APA writer, CSTF2, is upregulated by TGF-ß and CSTF2 facilitates TGF-ß-induced FGF2 overexpression, forming a TGF-ß-CSTF2-FGF2 pro-fibrotic axis in TEC. CSTF2 is a potentially promising target for renal fibrosis that does not directly disrupt TGF-ß.

First Infertile Case with CSTF2TGene Mutation.

Male infertility is multifactorial and presents with heterogeneous phenotypic features. Genetic factors are responsible for up to 15% of the male infertility cases. Loss of the Cstf2t gene in male mice results in infertility. No disease-associated mutations have been described for this gene in infertile men. Here, we report a patient diagnosed with infertility in whom a homozygous nonsense mutation in the CSTF2T gene was detected by clinical exome sequencing. This case is the first description of an infertile patient who has a homozygous CSTF2T mutation.

A Novel Regulatory Function of Long Non-coding RNAs at Different Levels of Gene Expression in Multiple Sclerosis.

Long non-coding RNAs (lncRNAs) play critical roles in regulation of immunological pathways. Consequently, their expression profile represents new biomarkers for susceptibility and progression of immunological disorders. However, their role in chronic inflammatory diseases such as multiple sclerosis (MS) remained unknown. Here, we assessed the expression of lncRNAs MALAT1 and HOTAIRM1 as well as their target genes in peripheral blood of MS patients to show their possible roles in disease initiation and progression. In this study, 50 patients with relapsing-remitting MS and 50 healthy matched controls were enrolled. Comparative Ct method via TaqMan assay was used to quantify transcript levels of MALAT1, HOTAIRM1, AGO2, CSTF2, CPSF7, and WDR33. Our analysis depicted significant differences in lncRNAs and their target genes expression levels. AGO2 expression was significantly elevated in MS patients (P < 0.001) whereas, CSTF2 expiration was considerably down-regulated (P < 0.042). These findings suggest that AGO2 and CSTF2 can be considered as potential theoretical biomarkers for MS and can be helpful for diagnosis and prognosis of responding patients to interferon.

Implications of polyadenylation in health and disease.

Polyadenylation is the RNA processing step that completes the maturation of nearly all eukaryotic mRNAs. It is a two-step nuclear process that involves an endonucleolytic cleavage of the pre-mRNA at the 3'-end and the polymerization of a polyadenosine (polyA) tail, which is fundamental for mRNA stability, nuclear export and efficient translation during development. The core molecular machinery responsible for the definition of a polyA site includes several recognition, cleavage and polyadenylation factors that identify and act on a given polyA signal present in a pre-mRNA, usually an AAUAAA hexamer or similar sequence. This mechanism is tightly regulated by other cis-acting elements and trans-acting factors, and its misregulation can cause inefficient gene expression and may ultimately lead to disease. The majority of genes generate multiple mRNAs as a result of alternative polyadenylation in the 3'-untranslated region. The variable lengths of the 3' untranslated regions created by alternative polyadenylation are a recognizable target for differential regulation and clearly affect the fate of the transcript, ultimately modulating the expression of the gene. Over the past few years, several studies have highlighted the importance of polyadenylation and alternative polyadenylation in gene expression and their impact in a variety of physiological conditions, as well as in several illnesses. Abnormalities in the 3'-end processing mechanisms thus represent a common feature among many oncological, immunological, neurological and hematological disorders, but slight imbalances can lead to the natural establishment of a specific cellular state. This review addresses the key steps of polyadenylation and alternative polyadenylation in different cellular conditions and diseases focusing on the molecular effectors that ensure a faultless pre-mRNA 3' end formation.

Polyadenylation site-specific differences in the activity of the neuronal ßCstF-64 protein in PC-12 cells.

Recent genome-wide analyses have implicated alternative polyadenylation - the process of regulated mRNA 3' end formation - as a critical mechanism that influences multiple steps of mRNA metabolism in addition to increasing the protein-coding capacity of the genome. Although the functional consequences of alternative polyadenylation are well known, protein factors that regulate this process are poorly characterized. Previously, we described an evolutionarily conserved family of neuronal splice variants of the CstF-64 mRNA, ßCstF-64, that we hypothesized to function in alternative polyadenylation in the nervous system. In the present study, we show that ßCstF-64 mRNA and protein expression increase in response to nerve growth factor (NGF), concomitant with differentiation of adrenal PC-12 cells into a neuronal phenotype, suggesting a role for ßCstF-64 in neuronal gene expression. Using PC-12 cells as model, we show that ßCstF-64 is a bona fide polyadenylation protein, as evidenced by its association with the CstF complex, and by its ability to stimulate polyadenylation of luciferase reporter mRNA. Using luciferase assays, we show that ßCstF-64 stimulates polyadenylation equivalently at the two weak poly(A) sites of the ß-adducin mRNA. Notably, we demonstrate that the activity of ßCstF-64 is less than CstF-64 on a strong polyadenylation signal, suggesting polyadenylation site-specific differences in the activity of the ßCstF-64 protein. Our data address the polyadenylation functions of ßCstF-64 for the first time, and provide initial insights into the mechanism of alternative poly(A) site selection in the nervous system.