Alternative splicing of the OCC-1 gene generates three splice variants and a novel exonic microRNA, which regulate the Wnt signaling pathway

Targeted splicing therapy: new strategies for colorectal cancer

RNA splicing is the process of forming mature mRNA, which is an essential phase necessary for gene expression and controls many aspects of cell proliferation, survival, and differentiation. Abnormal gene-splicing events are closely related to the development of tumors, and the generation of oncogenic isoform in splicing can promote tumor progression. As a main process of tumor-specific splicing variants, alternative splicing (AS) can promote tumor progression by increasing the production of oncogenic splicing isoforms and/or reducing the production of normal splicing isoforms. This is the focus of current research on the regulation of aberrant tumor splicing. So far, AS has been found to be associated with various aspects of tumor biology, including cell proliferation and invasion, resistance to apoptosis, and sensitivity to different chemotherapeutic drugs. This article will review the abnormal splicing events in colorectal cancer (CRC), especially the tumor-associated splicing variants arising from AS, aiming to offer an insight into CRC-targeted splicing therapy.

A Novel miRNA Located in the HER2 Gene Shows an Inhibitory Effect on Wnt Signaling and Cell Cycle Progression

Human epidermal growth factor receptor 2 (HER2) is involved in the development of the majority of cancers. Therefore, it can be a potential target for cancer therapy. It was hypothesized that some of the broad effects of HER2 could be mediated by miRNAs that are probably embedded inside this gene. Here, we predicted and then empirically substantiated the processing and expression of a novel miRNA named HER2-miR1, located in the HER2 gene; transfection of a DNA fragment corresponding to HER2-miR1 precursor sequence (preHER2-miR1) resulted in ~4000-fold elevation of HER2-miR1 mature form in HEK293t cells. Also, the detection of HER2-miR1 in 5637, NT2, and HeLa cell lines confirmed its endogenous production. Following the HER2-miR1 overexpression, TOP/FOP flash assay and RT-qPCR results showed that Wnt signaling pathway was downregulated. Consistently, flow cytometry results revealed that overexpression of HER2-miR1 in Wnt⁺ cell lines (SW480 and HCT116) was ended in G1 arrest, unlike in Wnt⁻ cells (HEK293t). Taking everything into account, our results report the discovery of a novel miRNA that is located within the HER2 gene sequence and has a repressive impact on the Wnt signaling pathway.

Pan-cancer analysis of the prognostic value of C12orf75 based on data mining

The differential expression of chromosome 12 open reading frame 75 (C12orf75) is closely related with cancer progression. Here, we studied the expression levels of C12orf75 and investigated its prognostic value in various cancers across distinct datasets including ONCOMINE, PrognoScan, GEPIA, and TCGA. The correlation between genetic alteration of C12orf75 and immune infiltration was investigated using the cBioPortal and TIMER databases. RNA interference was used to verify the influence of C12orf75 knockdown on the biological phenotype of hepatocellular carcinoma cells. C12orf75 showed increased expression in most tested human cancers. The increased expression of C12orf75 was related with a poor prognosis in urothelial bladder carcinoma and hepatocellular liver carcinoma, but it was surprisingly converse in renal papillary cell carcinoma. In urothelial bladder carcinoma and hepatocellular liver carcinoma, we observed positive correlations between the expression of C12orf75 and the infiltration of immune cells, including B cells, CD8+ T cells, CD4+ T cells, macrophages, neutrophils, and dendritic cells. The knockdown of C12orf75 in hepatocellular carcinoma cells suppressed the proliferation, migration, and invasion and arrested the cell cycle. This is the first report C12orf75 has potential as a prognostic biomarker and therapeutic target for molecularly targeted drugs in urothelial bladder carcinoma, hepatocellular liver carcinoma, and renal papillary cell carcinoma.

Skeletal muscle transcriptome in healthy aging

Age-associated changes in gene expression in skeletal muscle of healthy individuals reflect accumulation of damage and compensatory adaptations to preserve tissue integrity. To characterize these changes, RNA was extracted and sequenced from muscle biopsies collected from 53 healthy individuals (22-83 years old) of the GESTALT study of the National Institute on Aging-NIH. Expression levels of 57,205 protein-coding and non-coding RNAs were studied as a function of aging by linear and negative binomial regression models. From both models, 1134 RNAs changed significantly with age. The most differentially abundant mRNAs encoded proteins implicated in several age-related processes, including cellular senescence, insulin signaling, and myogenesis. Specific mRNA isoforms that changed significantly with age in skeletal muscle were enriched for proteins involved in oxidative phosphorylation and adipogenesis. Our study establishes a detailed framework of the global transcriptome and mRNA isoforms that govern muscle damage and homeostasis with age.

Long Noncoding RNA LOC400043 (LINC02381) Inhibits Gastric Cancer Progression Through Regulating Wnt Signaling Pathway

Gastric cancer is one of the common causes of cancer mortality worldwide, with a low survival rate for the affected people. Recent studies have revealed the key role of long non-coding RNAs (lncRNAs) in the development and progression of many cancers, including gastric cancer. Looking for the potential molecular regulators of gastric cancer incidence and progression, LINC02381 was identified as a downregulated lncRNA in gastric cancer tissues by analysis of available microarray and RNA-seq data and RT-qPCR confirmed this differential expression. MiR-21, miR-590, and miR-27a miRNAs were predicted to be sponged by LINC02381, and dual luciferase assay verified LINC02381 as a competitive endogenous RNA (CeRNA), which binds to them. Furthermore, we found that increased expression of LINC02381 attenuates Wnt pathway activity. Also, functional analysis indicates that LINC02381 arrests cell cycle, increases apoptosis and caspase activity, and reduces cell survival and proliferation rate of the human gastric cancer cell lines AGS and MKN45. Moreover, EMT analysis showed that LINC02381 is involved in gastric cancer progression and inhibits metastasis. Overall, this work for the first time introduces LINC02381 as a CeRNA involved in gastric cancer and provides novel insight into the molecular pathogenesis of gastric cancer.

A novel miRNA located in the GATA4 gene regulates the expression of IGF-1R and AKT1/2 genes and controls cell proliferation

GATA4 gene is a zinc-finger transcription factor known to be involved in cardiogenesis and the progression of different cancer types. Its diverse functions might be attributed to noncoding RNAs that could be embedded within its sequence. Here, we predicted a stable RNA stem-loop structure that is located in the second intron of the GATA4 gene. Available microRNA (miRNA) sequencing data and molecular genetics tools confirmed the identity of a mature miRNA (named GATA4-miR1) originating from the predicted stem-loop. In silico analysis predicted IGF-1R and AKT1/2 genes as potential targets for GATA4-miR1. Indeed, direct interactions between GATA4-miR1 and 3' untranslated regions sequences of IGF-1R and AKT1/2 genes were documented by dual luciferase assay. In addition, overexpression of GATA4-miR1 in SW480 cells resulted in the reduction of IGF-1R and AKT1/2 genes' expression, detected by reverse transcription quantitative (RT-q) polymerase chain reaction and Western blot analysis. This observation was consistent with a deduced negative correlation between the expression patterns of GATA4-miR1 and IGF-1R genes during cardiomyocyte differentiation. Moreover, overexpressing GATA4-miR1 in SW480 and PC3 cells resulted in a significant increase of the sub-G1 population in both cell lines, as detected by propidium iodide flow cytometry. Further analysis by 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide assay indicated a reduction in the survival and proliferation rates of SW480 cells overexpressing GATA4-miR1, but no impact was observed on apoptosis progression, as indicated by Annexin-V flow cytometry. Overall, GATA4-miR1 represents a promising candidate for further research in the fields of cancer and cardiovascular therapeutics.

Regulatory effect of hsa-miR-5590-3P on TGFβ signaling through targeting of TGFβ-R1, TGFβ-R2, SMAD3 and SMAD4 transcripts

Transforming growth factor-β (TGFβ) signaling acts as suppressor and inducer of tumor progression during the early and late stages of cancer, respectively. Some miRNAs have shown a regulatory effect on TGFβ signaling and here, we have used a combination of bioinformatics and experimental tools to show that hsa-miR-5590-3p is a regulator of multiple genes expression in the TGFβ signaling pathway. Consistent with the bioinformatics predictions, hsa-miR-5590-3p had a negative correlation of expression with TGFβ-R1, TGFβ-R2, SMAD3 and SMAD4 genes, detected by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Then, the dual luciferase assay supported the direct interaction between hsa-miR-5590-3p and TGFβ-R1, TGFβ-R2, SMAD3 and SMAD4-3'UTR sequences. Consistently, the TGFβ-R1 protein level was reduced following the overexpression of hsa-miR-5590-3p, detected by Western analysis. Also, hsa-miR-5590-3p overexpression brought about the downregulation of TGFβ-R1, TGFβ-R2, SMAD3 and SMAD4 expression in HCT-116 cells, detected by RT-qPCR, followed by cell cycle arrest in the sub-G1 phase, detected by flow cytometry. RT-qPCR results indicated that hsa-miR-5590-3p is significantly downregulated in breast tumor tissues (late stage) compared to their normal pairs. Altogether, data introduces hsa-miR-5590-3p as a negative regulator of the TGFβ/SMAD signaling pathway which acts through downregulation of TGFβ-R1, TGFβ-R2, SMAD3 and SMAD4 transcripts. Therefore, it can be tested as a therapy target in cancers in which the TGFβ/SMAD pathway is deregulated.

Long noncoding RNA OCC-1 suppresses cell growth through destabilizing HuR protein in colorectal cancer

Overexpressed in colon carcinoma-1 (OCC-1) is one of the earliest annotated long noncoding RNAs (lncRNAs) in colorectal cancer (CRC); however, its function remains largely unknown. Here, we revealed that OCC-1 plays a tumor suppressive role in CRC. OCC-1 knockdown by RNA interference promotes cell growth both in vitro and in vivo, which is largely due to its ability to inhibit G0 to G1 and G1 to S phase cell cycle transitions. In addition, overexpression of OCC-1 can suppress cell growth in OCC-1 knockdown cells. OCC-1 exerts its function by binding to and destabilizing HuR (ELAVL1), a cancer-associated RNA binding protein (RBP) which can bind to and stabilize thousands of mRNAs. OCC-1 enhances the binding of ubiquitin E3 ligase β-TrCP1 to HuR and renders HuR susceptible to ubiquitination and degradation, thereby reducing the levels of HuR and its target mRNAs, including the mRNAs directly associated with cancer cell growth. These findings reveal that lncRNA OCC-1 can regulate the levels of a large number of mRNAs at post-transcriptional level through modulating RBP HuR stability.

Hsa-miR-335 regulates cardiac mesoderm and progenitor cell differentiation

Background

WNT and TGFβ signaling pathways play critical regulatory roles in cardiomyocyte fate determination and differentiation. MiRNAs are also known to regulate different biological processes and signaling pathways. Here, we intended to find candidate miRNAs that are involved in cardiac differentiation through regulation of WNT and TGFβ signaling pathways.

Methods

Bioinformatics analysis suggested hsa-miR-335-3p and hsa-miR-335-5p as regulators of cardiac differentiation. Then, RT-qPCR, dual luciferase, TOP/FOP flash, and western blot analyses were done to confirm the hypothesis.

Results

Human embryonic stem cells (hESCs) were differentiated into beating cardiomyocytes, and these miRNAs showed significant expression during the differentiation process. Gain and loss of function of miR-335-3p and miR-335-5p resulted in BRACHYURY, GATA4, and NKX2-5 (cardiac differentiation markers) expression alteration during the course of hESC cardiac differentiation. The overexpression of miR-335-3p and miR-335-5p also led to upregulation of CNX43 and TNNT2 expression, respectively. Our results suggest that this might be mediated through enhancement of WNT and TGFβ signaling pathways.

Conclusion

Overall, we show that miR-335-3p/5p upregulates cardiac mesoderm (BRACHYURY) and cardiac progenitor cell (GATA4 and NKX2-5) markers, which are potentially mediated through activation of WNT and TGFβ signaling pathways. Our findings suggest miR-335-3p/5p to be considered as a regulator of the cardiac differentiation process.

Electronic supplementary material

The online version of this article (10.1186/s13287-019-1249-2) contains supplementary material, which is available to authorized users.

Overexpressed in colorectal carcinoma gene (OCC-1) upregulation and APPL2 gene downregulation in breast cancer specimens

Breast cancer is the most common cancer type and the second cause of cancer death in women. Different mechanisms are contributed to the initiation and progression of the breast cancer. OCC-1 and APPL2 neighboring genes located in 12q.23.3 human chromosome region are related to colorectal cancer. Here, we intended to investigate OCC-1 newly reported transcript variants and APPL2 gene expression alteration in breast cancer specimens and investigate OCC-1 variants overexpression effect on APPL2 and on cell cycle status. Rt-qPCR analysis indicated that the expression level of OCC-1A/B and OCC-1D (not OCC-1C) transcript variants has been increased while, APPL2 gene expression level has been decreased in breast cancer specimen, compared to their normal pairs. Therefore, a negative correlation of expression is evident between APPL2 and OCC-1 genes in breast cancer specimen. Unlike OCC-1A/B which encodes a small protein, OCC-1D noncoding RNA overexpression lead to APPL2 downregulation in MCF7 cells. Consistently, OCC-1D overexpression resulted in increased sub-G1 cell population in MCF7 cells, detected by flow cytometry. Altogether, these results suggest that OCC1-D variant have an inhibitory effect on APPL2 expression and may regulate the cell cycle status.

Hsa-miR-5582-3P regulatory effect on TGFβ signaling through targeting of TGFβ-R1, TGFβ-R2, SMAD3, and SMAD4 transcripts

Transforming growth factor β (TGFβ) signaling pathway which is regulated by factors such as microRNAs (miRNAs) has pivotal roles in various cellular processes. Here, we intended to verify bioinformatics predicted regulatory effect of hsa-miR-5582-3P against TGFβ/SMAD signaling pathway components. Quantitative reverse-transcription polymerase chain reaction (RT-qPCR) analysis indicated a negative correlation of expression between hsa-miR-5582-3P against TGFβ-R1, TGFβ-R2, SMAD3, and SMAD4 putative target genes in all of tested cell lines. Also, hsa-miR-5582-3P was significantly downregulated in glioma, breast, and ovarian tumor tissues compared with their normal pairs, detected by RT-qPCR. Then dual luciferase assay supported direct interaction between this miRNA and TGFβ-R1, TGFβ-R2, SMAD3, and SMAD4, 3' untranslated region sequences. Western blot analysis confirmed negative effect of hsa-miR-5582-3P overexpression on at least TGFβ-R1 expression. Consistently, hsa-miR-5582-3P overexpression brought about downregulation of TGFβ-R1, TGFβ-R2, SMAD3, and SMAD4 expression in HCT-116 cell line, followed by cell cycle arrest in sub-G1 phase, detected by flow cytometry. Altogether, our data suggest that hsa-miR-5582-3P reduces the TGFβ/SMAD signaling pathway through downregulation of TGFβ-R1, TGFβ-R2, SMAD3, and SMAD4 transcripts. These data introduce hsa-miR-5582-3P as a potential tumor suppressors-miR and a therapy candidate to be tested in cancers in which TGFβ/SMAD is deregulated.

COPD is accompanied by co-ordinated transcriptional perturbation in the quadriceps affecting the mitochondria and extracellular matrix

Skeletal muscle dysfunction is a frequent extra-pulmonary manifestation of Chronic Obstructive Pulmonary Disease (COPD) with implications for both quality of life and survival. The underlying biology nevertheless remains poorly understood. We measured global gene transcription in the quadriceps using Affymetrix HuGene1.1ST arrays in an unselected cohort of 79 stable COPD patients in secondary care and 16 healthy age- and gender-matched controls. We detected 1,826 transcripts showing COPD-related variation. Eighteen exhibited ≥2fold changes (SLC22A3, FAM184B, CDKN1A, FST, LINC01405, MUSK, PANX1, ANKRD1, C12orf75, MYH1, POSTN, FRZB, TNC, ACTC1, LINC00310, MYH3, MYBPH and AREG). Thirty-one transcripts possessed previous reported evidence of involvement in COPD through genome-wide association, including FAM13A. Network analysis revealed a substructure comprising 6 modules of co-expressed genes. We identified modules with mitochondrial and extracellular matrix features, of which IDH2, a central component of the mitochondrial antioxidant pathway, and ABI3BP, a proposed switch between proliferation and differentiation, represent hubs respectively. COPD is accompanied by coordinated patterns of transcription in the quadriceps involving the mitochondria and extracellular matrix and including genes previously implicated in primary disease processes.

The expression and significance of microRNA in different stages of colorectal cancer

BACKGROUND

The aim of this study is to compare microRNA expression patterns in different stages of colorectal cancer (CRC) and to discuss the significance of the application of microRNAs in the clinical treatment of CRC.

METHODS

The study used gene chip technology to analyze genetic sequences in CRC tissues and surrounding normal tissues at different cancer stages. The bioinformatics profiles of the target genes of the different microRNAs were analyzed to clarify the target gene-related pathways and their functions in the disease.

RESULTS

A total of 368 target genes with differential expression, including 275 upregulated and 93 downregulated genes, were screened from CRC patients in different stages of the disease. These microRNAs participated widely in the occurrence and development processes of CRC. The microRNA expression profiles obviously differed in tissues at different CRC stages.

CONCLUSION

microRNA regulation of CRC samples can be used as a tool to control the occurrence and development of tumor cells.

Identification of a novel intergenic miRNA located between the human DDC and COBL genes with a potential function in cell cycle arrest

Frequent abnormalities in 7p12 locus in different tumors like lung cancer candidate this region for novel regulatory elements. MiRNAs as novel regulatory elements encoded within the human genome are potentially oncomiRs or miR suppressors. Here, we have used bioinformatics tools to search for the novel miRNAs embedded within human chromosome 7p12. A bona fide stem loop (named mirZa precursor) had the features of producing a real miRNA (named miRZa) which was detected through RT-qPCR following the overexpression of its precursor. Then, endogenous miRZa was detected in human cell lines and tissues and sequenced. Consistent to the bioinformatics prediction, RT-qPCR as well as dual luciferase assay indicated that SMAD3 and IGF1R genes were targeted by miRZa. MiRZa-3p and miRZa-5p were downregulated in lung tumor tissue samples detected by RT-qPCR, and mirZa precursor overexpression in SW480 cells resulted in increased sub-G1 cell population. Overall, here we introduced a novel miRNA which is capable of targeting SMAD3 and IGF1R regulatory genes and increases the cell population in sub-G1 stage.