Oncogenic Role In Colorectal Cancer Research Articles

TCF7L1 regulates colorectal cancer cell migration by repressing GAS1 expression

Dysregulated Wnt/β-catenin signaling is a common feature of colorectal cancer (CRC). The T-cell factor/lymphoid enhancer factor (TCF/LEF; hereafter, TCF) family of transcription factors are critical regulators of Wnt/β-catenin target gene expression. Of the four TCF family members, TCF7L1 predominantly functions as a transcriptional repressor. Although TCF7L1 has been ascribed an oncogenic role in CRC, only a few target genes whose expression it regulates have been characterized in this cancer. Through transcriptome analyses of TCF7L1 regulated genes, we noted enrichment for those associated with cellular migration. By silencing and overexpressing TCF7L1 in CRC cell lines, we demonstrated that TCF7L1 promoted migration, invasion, and adhesion. We localized TCF7L1 binding across the CRC genome and overlapped enriched regions with transcriptome data to identify candidate target genes. The growth arrest-specific 1 (GAS1) gene was among these and we demonstrated that GAS1 is a critical mediator of TCF7L1-dependent CRC cell migratory phenotypes. Together, these findings uncover a novel role for TCF7L1 in repressing GAS1 expression to enhance migration and invasion of CRC cells.

EIf3a mediates malignant biological behaviors in colorectal cancer through the PI3K/AKT signaling pathway

ABSTRACT Colorectal cancer (CRC) is among the most common gastrointestinal malignancies worldwide. eIF3a is highly expressed in a variety of cancer types, yet its role in CRC remains unclear. We introduced ectopic eIF3a expression in CRC cells to investigate its relevance to various malignant behaviors. Further, we silenced eIF3a to explore its effect on tumor growth in a nude mouse tumor xenograft model. Finally, the molecular mechanisms through which eIF3a regulates malignancy in CRC cells were explored through bioinformatics analysis combined with the use of a specific PI3K inhibitor (LY294002). eIF3a was highly expressed in the peripheral blood and cancer tissue of CRC patients. Malignancy and tumor growth were significantly inhibited by silencing eIF3a, while overexpression promoted malignant behaviors, with a positive correlation between PI3K/AKT activation and eIF3a expression. Taken together, eIF3a plays an oncogenic role in CRC by regulating PI3K/AKT signaling and is a potential biomarker for CRC diagnosis and prognostic monitoring.

Circ_0007351 Exerts an Oncogenic Role In Colorectal Cancer Depending on the Modulation of the miR-5195-3p/GPRC5A Cascade.

Circular RNAs (circRNAs) exert critical functions in colorectal cancer development. In this work, we wanted to elucidate the functional role and regulatory mechanism of circ_0007351 in colorectal cancer. For quantification of circ_0007351, microRNA (miR)-5195-3p and G Protein-coupled receptor class C group 5 member A (GPRC5A), a qRT-PCR, immunoblotting or immunohistochemistry assay was performed. Effects of circ_0007351/miR-5195-3p/GPRC5A cascade were evaluated by determining cell viability, proliferation, colony formation, motility, and invasion. Relationships among variables were assessed by dual-luciferase reporter assay. Animal studies were performed to evaluate circ_0007351's function in the growth of xenograft tumors. Circ_0007351 was markedly up-regulated in colorectal cancer tissues and cells. Down-regulation of circ_0007351 hindered cell growth, migration and invasiveness. Also, circ_0007351 depletion exerted a suppressive function in colorectal cell xenograft growth in vivo. Mechanistically, circ_0007351 sponged miR-5195-3p to sequester miR-5195-3p. Reduction of available miR-5195-3p neutralized the effects of circ_0007351 down-regulation on cell phenotypes. MiR-5195-3p directly targeted and inhibited GPRC5A. Circ_0007351 regulated GPRC5A expression by sponging miR-5195-3p. Moreover, the effects of circ_0007351 down-regulation on cell functional phenotypes were due to in part the reduction of GPRC5A expression. Our findings show that circ_0007351 down-regulation impedes proliferation, motility, and invasiveness in colorectal cancer cells at least in part via the regulation of the miR-5195-3p/GPRC5A cascade, highlighting that circ_0007351 inhibition may have a potential therapeutic value for colorectal cancer.

Circ_0000370 Plays an Oncogenic Role in Colorectal Cancer by Regulating the miR-502-5p/SIRT1 Axis.

The importance of circular RNA has been reported in cancer development. However, the role and mechanism of circ_0000370 in CRC progression are still unclear. Quantitative real-time PCR and Western blot assay were performed to measure RNA and protein expression. Cell proliferation was assessed by cell colony formation assay and 5-Ethynyl-2'-deoxyuridine assay. Flow cytometry was used to measure cell apoptosis. Cell migration and invasion were detected by transwell assay. The intermolecular target relations between miR-502-5p and circ_0000370 or SIRT1 were confirmed by dual-luciferase reporter assay and RNA immunoprecipitation assay. A xenograft tumor model was established to examine the role of circ_0000370 in tumor growth in vivo. As compared with controls, the expression of circ_0000370 was upregulated in CRC tissues and cells. Circ_0000370 depletion inhibited CRC cell proliferation, migration and invasion but induced cell apoptosis. Meanwhile, circ_0000370 depletion restrained tumor growth in vivo. In addition, miR-502-5p inhibitor partly reverted the impacts of circ_0000370 knockdown on CRC cells. Moreover, miR-502-5p mimic-caused effects on cell phenotypes were attenuated by SIRT1 overexpression. Circ_0000370 induced the proliferation and metastasis of CRC cells by sponging miR-502-5p and enhancing SIRT1 expression, which provided a possible target for CRC treatment.

MLF2 Negatively Regulates P53 and Promotes Colorectal Carcinogenesis.

Inactivation of the p53 pathway is linked to a variety of human cancers. As a critical component of the p53 pathway, ubiquitin-specific protease 7 (USP7) acts as a deubiquitinase for both p53 and its ubiquitin E3 ligase mouse double minute 2 homolog. Here, myeloid leukemia factor 2 (MLF2) is reported as a new negative regulator of p53. MLF2 interacts with both p53 and USP7. Via these interactions, MLF2 inhibits the binding of USP7 to p53 and antagonizes USP7-mediated deubiquitination of p53, thereby leading to p53 destabilization. Functionally, MLF2 plays an oncogenic role in colorectal cancer, at least partially, via the negative regulation of p53. Clinically, MLF2 is elevated in colorectal cancer and its high expression is associated with poor prognosis in patients with colorectal cancer. In wild-type-p53-containing colorectal cancer, MLF2 and p53 expressions are inversely correlated. These findings establish MLF2 as an important suppressor of p53 function. The study also reveals a critical role for the MLF2-p53 axis in promoting colorectal carcinogenesis.

Abstract PR009: RNF43 G659fs is an oncogenic and immune-modulating colorectal cancer mutation and sensitizes tumor cells to PI3K/mTOR inhibition

Abstract Introduction: The RNF43 p.G659fs mutation occurs with a frequency of approximately 8% in colorectal cancer (CRC) and is enriched among microsatellite-instability high tumors. However, despite RNF43 being implicated as a Wnt-signaling tumor suppressor, the function of the RNF43 p.G659fs mutation remains undescribed, with no specific therapies directed against it. We hypothesized that large-scale drug screening coupled with functional validation and testing in CRC pre-clinical models would reveal the functional role and selective vulnerabilities of this alteration, leading to new therapeutic approaches in CRC. Methods: We targeted the RNF43 659 site with CRISPR-Cas9 to generate isogenic RNF43659mut clones of CRC cell lines. We leveraged the Broad Institute’s drug repurposing library of over 5,300 compounds to identify selective hits (z<-3 vs DMSO, >5% selective killing in mutant vs WT) in RNF43659mut isogenic cells. These hits were validated in secondary screens and top drugs were tested in patient-derived organoid and xenograft models of the RNF43 p.G659fs mutation. We assessed the functional role of the mutation using cell viability and colony formation assays, quantitative mass spectrometry proteomics, immunoprecipitation and ubiquitination experiments. The immunomodulatory role of RNF43659mut was assessed through bulk and single-cell RNA Seq analysis of mutant cell lines and patient-derived CRC specimens. Results: Using edited cell line models, we demonstrated that RNF43 p.G659fs has a Wnt-independent oncogenic role in CRC. We performed a comprehensive drug screen in isogenic RNF43659mut HT29 CRC cells with a repurposing library of 5,363 compounds and discovered that RNF43659mut is selectively targeted by PI3K/mTOR inhibitors (p = 1.34 x 10-5, chi-square test). Secondary screens in LS513 RNF43659mut-edited and HCT116 RNF43G659fs-overexpressing cells confirmed these results and we further showed that alpelisib and PF-04691502 (a dual PI3K/mTOR inhibitor) selectively killed patient-derived organoids with the RNF43 p.G659Vfs mutation and reduced tumor growth in RNF43659mut CDX mice (p=0.0005, Student’s t-test). RNF43 p.G659fs increased PI3K/AKT signaling in vitro and in vivo through binding, ubiquitinating and degrading p85 and this was reversed by PI3K/mTOR inhibition, RNF43 knockout or RSPO stimulation. Additionally, in pre-clinical models and single-cell studies of human CRCs (>350,000 single cells), we found that RNF43659mut modulates interferon activity and NK cells in the CRC tumor microenvironment. Conclusions: Through functional and pharmacologic studies in pre-clinical models and human CRCs, we described that RNF43 p.G659fs activates PI3K/AKT signaling and modulates the CRC immune microenvironment. We showed that these effects are reversed with PI3K/mTOR inhibitors and that this class of drugs selectively targets RNF43659mut CRCs. Our results have important therapeutic implications for patients with CRC. Citation Format: Marios Giannakis, Lishan Fang, Dane Ford-Roshon, Max Russo, Casey O'Brien, Xiaozhe Xiong, Carino Gurjao, Maximilien Grandclaudon, Srivatsan Raghavan, Steven M. Corsello, Steven A. Carr, Namrata Udeshi, James Berstler, Ewa Sicinska, Kimmie Ng. RNF43 G659fs is an oncogenic and immune-modulating colorectal cancer mutation and sensitizes tumor cells to PI3K/mTOR inhibition [abstract]. In: Proceedings of the AACR Special Conference on Colorectal Cancer; 2022 Oct 1-4; Portland, OR. Philadelphia (PA): AACR; Cancer Res 2022;82(23 Suppl_1):Abstract nr PR009.

Integrated analysis of genes encoding ATP‐dependent chromatin remodellers identifies CHD7 as a potential target for colorectal cancer therapy

BackgroundGenes participating in chromatin organization and regulation are frequently mutated or dysregulated in cancers. ATP‐dependent chromatin remodelers (ATPCRs) play a key role in organizing genomic DNA within chromatin, therefore regulating gene expression. The oncogenic role of ATPCRs and the mechanism involved remains unclear.MethodsWe analyzed the genomic and transcriptional aberrations of the genes encoding ATPCRs in The Cancer Genome Atlas (TCGA) cohort. A series of cellular experiments and mouse tumor‐bearing experiments were conducted to reveal the regulatory function of CHD7 on the growth of colorectal cancer cells. RNA‐seq and ATAC‐seq approaches together with ChIP assays were performed to elucidate the downstream targets and the molecular mechanisms.ResultsOur data showed that many ATPCRs represented a high frequency of somatic copy number alterations, widespread somatic mutations, remarkable expression abnormalities, and significant correlation with overall survival, suggesting several somatic driver candidates including chromodomain helicase DNA‐binding protein 7 (CHD7) in colorectal cancer. We experimentally demonstrated that CHD7 promotes the growth of colorectal cancer cells in vitro and in vivo. CHD7 can bind to the promoters of target genes to maintain chromatin accessibility and facilitate transcription. We found that CHD7 knockdown downregulates AK4 expression and activates AMPK phosphorylation, thereby promoting the phosphorylation and stability of p53 and leading to the inhibition of the colorectal cancer growth. Our muti‐omics analyses of ATPCRs across large‐scale cancer specimens identified potential therapeutic targets and our experimental studies revealed a novel CHD7‐AK4‐AMPK‐p53 axis that plays an oncogenic role in colorectal cancer.

CircCTNNA1 is Upregulated in Mantle Cell Lymphoma and Predicts Poor Survival by Sponging miR-34a to Increase Cell Proliferation.

BackgroundIt was reported that circular RNA (circRNA) circCTNNA1 plays an oncogenic role in colorectal cancer, while its role in mantle cell lymphoma (MCL) is unknown. This study aimed to explore the role of circCTNNA1 in MCL.MethodsSamples of B lymphocytes were collected from 56 MCL patients and 56 healthy controls. The expression of circCTNNA1 and miR-34a in these samples were determined by RT-qPCR. The direct interaction between circCTNNA1 and miR-34a in MCL cells was detected using RNA-RNA pulldown assay. Overexpression assays were performed to study the interactions between circCTNNA1 and miR-34a. Cell proliferation was assessed with BrdU assay.ResultsThe results showed that circCTNNA1 was upregulated in MCL and high expression levels of circCTNNA1 predicted the poor survival of MCL patients. MiR-34a was downregulated in MCL and inversely correlated with circCTNNA1. CircCTNNA1 was predicted to interact with miR-34a, and the interaction between them was confirmed by RNA pull-down assay. Interestingly, overexpression of circCTNNA1 and miR-34a did not affect the expression of each other. Cell proliferation analysis showed that overexpression of circCTNNA1 reversed the inhibitory effects of overexpression of miR-34a on cell proliferation.ConclusionUpregulation of circCTNNA1 in MCL predicts poor survival of patients and it may sponge miR-34a to promote cancer cell proliferation.

TCN1 Deficiency Inhibits the Malignancy of Colorectal Cancer Cells by Regulating the ITGB4 Pathway.

This study aimed to investigate the biological function and regulatory mechanism of TCN1 in colorectal cancer (CRC). We studied the biological function of TCN1 by performing gain-of-function and loss-of-function analyses in HCT116 cell lines; examined the effects of TCN1 on the proliferation, apoptosis, and invasion of CRC cells; and determined potential molecular mechanisms using HCT116 and SW480 CRC lines and mouse xenotransplantation models. Tumor xenograft and colonization assays were performed to detect the tumorigenicity and metastatic foci of cells in vivo. TCN1 knockdown attenuated CRC cell proliferation and invasion and promoted cell apoptosis. Overexpression of TCN1 yielded the opposite effects. In addition, TCN1-knockdown HCT116 cells failed to form metastatic foci in the peritoneum after intravenous injection. Molecular mechanism analyses showed that TCN1 interacted with integrin subunit β4 (ITGB4) to positively regulate the expression of ITGB4. TCN1 knockdown promoted the degradation of ITGB4 and increased the instability of ITGB4 and filamin A. Downregulation of ITGB4 at the protein level resulted in the disassociation of the ITGB4/plectin complex, leading to cytoskeletal damage. TCN1 might play an oncogenic role in CRC by regulating the ITGB4 signaling pathway.

Long Noncoding RNA CBR3-AS1 Promotes Stem-like Properties and Oxaliplatin Resistance of Colorectal Cancer by Sponging miR-145-5p.

Accumulating articles indicate that long noncoding RNAs (lncRNAs) serve as essential regulators in a plethora of human cancers. In this study, we analyzed the expression profile and functional role of lncRNA CBR3-AS1 in colorectal cancer (CRC). High-expression levels of CBR3-AS1 were found in CRC tissues and cell lines. Upregulated CBR3-AS1 was closely associated with poor prognosis and adverse clinicopathological features of CRC patients. Artificial knockdown of CBR3-AS1 markedly suppressed the proliferation, migration, invasion, and stem-like properties but promoted the apoptosis of CRC cells. Moreover, we observed that CBR3-AS1 could directly bind to miR-145-5p and negatively regulated its expression in CRC. Further experiments also demonstrated that inhibition of miR-145-5p reverted the effects of CBR3-AS1 knockdown on CRC cells. In addition, compared with the parental cells, CBR3-AS1 expression was strikingly increased in oxaliplatin- (OXA-) resistant CRC cells, and the OXA resistance was notably diminished by CBR3-AS1 knockdown. To conclude, our study suggested that CBR3-AS1 serves an oncogenic role in CRC and may be exploited as a novel therapeutic target for CRC patients.

LncRNA SNHG16 promotes colorectal cancer proliferation by regulating ABCB1 expression through sponging miR-214-3p.

Mounting evidence indicates that long non-coding RNAs (lncRNAs) have critical roles in colorectal cancer (CRC) progression, providing many potential diagnostic biomarkers, prognostic biomarkers, and treatment targets. Here, we sought to investigate the role and underlying regulatory mechanism of lncRNA small nucleolar RNA host gene 16 (SNHG16) in CRC. The expressions of SNHG16 in CRC were identified by RNA-sequencing and quantitative reverse transcription PCR. The functions of SNHG16 were explored by a series of in vitro and in vivo assays (colony formation assay, flow cytometry assay, and xenograft model). Bioinformatics analysis, RNA fluorescencein situ hybridization and luciferase reporter assay were used to investigate the regulatory mechanism of effects of SNHG16. SNHG16 was found to be significantly elevated in human CRC tissues and cell lines. Functional studies suggested that SNHG16 promoted CRC cell growth both in vitro and in vivo. Mechanistically, we identified that SNHG16 is expressed predominantly in the cytoplasm. SNHG16 could interact with miR-214-3p and up-regulated its target ABCB1. This study indicated that SNHG16 plays an oncogenic role in CRC, suggesting it could be a novel biomarker and therapeutic target in CRC.

Hepatocyte nuclear factor 4 gamma (HNF4G) is correlated with poor prognosis and promotes tumor cell growth by inhibiting caspase-dependent intrinsic apoptosis in colorectal cancer

The hepatocyte nuclear factor 4 gamma (HNF4G), a member of orphan nuclear receptors, is up-regulated and functions as an oncoprotein in a variety of tumors. Recent advances in understanding the biologic function and action mechanism of HNF4G in colorectal cancer (CRC) have not been fully elucidated. In the present study, we observed that HNF4G expression levels were significantly increased in CRC tissues compared with adjacent normal tissues, and HNF4G overexpression correlated with worse prognosis in colorectal cancer. Transfection with a small interference RNA (siRNA) targeting HNF4G in HCT116 and SW480 CRC cell lines significantly inhibited cell proliferation and promoted apoptosis in vitro. In contrast, overexpression of HNF4G increased cell proliferation and decreased the percentage of apoptotic cells. Moreover, we discovered that HNF4G was involved in CRC cell apoptosis via the caspase-dependent intrinsic pathway. Finally, knockdown of HNF4G expression led to attenuated colorectal cancer growth and promoted apoptosis in a xenograft mouse model. Collectively, these results indicate that HNF4G exerts as an oncogenic role in colorectal cancer and provides a potential therapeutic target.

CircTUBGCP3 Contributes to the Malignant Progression of Rectal Cancer.

Circular RNA (circRNA) tubulin gamma complex associated protein 3 (circTUBGCP3) has been reported to play an oncogenic role in colorectal cancer and osteosarcoma. We further assessed the role and working mechanism of circTUBGCP3 in rectal cancer progression. Colony formation assay and transwell assays were performed to analyze cell colony formation ability and motility. Flow cytometry was utilized to assess cell cycle progression and cell apoptosis. The production of lactate and the consumption of glucose were evaluated by fluorescence-based glucose/lactate assay kit to analyze cell glycolysis. The intermolecular interaction was verified by dual-luciferase reporter assay. In vivo experiments were carried out to analyze the role of circTUBGCP3 in tumor growth using xenograft tumor model. CircTUBGCP3 was significantly up-regulated in rectal cancer tissues and cell lines. CircTUBGCP3 interference inhibited the colony formation ability, migration, invasion, cell cycle progression, and glycolysis and promoted the apoptosis in rectal cancer cells. CircTUBGCP3 negative regulated microRNA-375 (miR-375) expression through interacting with it and circTUBGCP3 silencing-mediated effects in rectal cancer cells were largely based on the up-regulation of miR-375. Rho-associated coiled-coil-containing protein kinase 1 (ROCK1) was a target of miR-375, and ROCK1 was regulated by circTUBGCP3/miR-375 axis in rectal cancer cells. MiR-375 overexpression suppressed the malignant behaviors of rectal cancer cells partly through down-regulating ROCK1. CircTUBGCP3 interference restrained rectal cancer progression in vivo. CircTUBGCP3 acted as an oncogene to promote the malignant phenotypes of rectal cancer cells by modulating miR-375/ROCK1 axis.

Overexpression of dopamine receptor D2 promotes colorectal cancer progression by activating the β-catenin/ZEB1 axis.

Colorectal cancer (CRC) is a recurring cancer that is often resistant to conventional therapies and therefore requires the development of molecular‐based therapeutic approaches. Dopamine receptor D2 (DRD2) is associated with the growth of many types of tumors, but its oncogenic role in CRC is unclear. Here, we observed that elevated DRD2 expression was associated with a poor survival rate among patients with CRC. Depletion of DRD2 suppressed CRC cell growth and motility by downregulating β‐catenin/ZEB signaling in vitro and in vivo, whereas overexpression of DRD2 promoted CRC cell progression. Inhibition of DRD2 by the antagonist pimozide inhibited tumor growth and lymph node metastasis in vivo and enhanced the cytotoxic effects of conventional agents in vitro. Taken together, our findings indicate that targeting the DRD2/β‐catenin/ZEB1 signaling axis is a potentially promising therapeutic strategy for patients with CRC.

Long noncoding RNA LINC01296 plays an oncogenic role in colorectal cancer by suppressing p15 expression.

ObjectiveTo examine the role of the long noncoding RNA LINC01296 in colorectal carcinoma (CRC) and to explore the underlying mechanism.MethodsWe detected LINC01296 expression levels in a cohort of 51 paired CRC and normal tissues. We also assessed the effects of LINC01296 on cell proliferation and apoptosis in CRC cells in vitro, and measured its effect on tumor growth in an in vivo mouse model. We identified the potential downstream targets of LINC01296 and assessed its regulatory effects.ResultsExpression levels of LINC01296 were elevated in 37/51 CRC tissues compared with the corresponding normal tissues and were significantly associated with tumor stage, lymph node metastasis, and distant metastasis. Knockdown of LINC01296 using antisense oligonucleotides inhibited cell proliferation and promoted apoptosis of colon cancer cells in vitro and inhibited tumor growth in vivo. Knockdown of LINC01296 also significantly increased the gene expression of p15 in colon cancer cells. LINC01296-specific suppression of p15 was validated by the interaction between enhancer of zeste homolog 2 and LINC01296.ConclusionOverexpression of LINC01296 suppressed the expression of p15 leading to CRC carcinogenesis. These findings may provide the basis for novel future CRC-targeted therapies.

SNHG7 has an oncogenic role in colorectal cancer via potential sponging of MIR-485-5P and MIR-193A-5P; in silico approach

SNHG7, as a member of the small nucleolar host gene family, is a recently identified long non-coding RNA (lncRNA). Different reports have identified the SNHGs as competing endogenous RNAs (ceRNAs) sponging miRNAs with a role in cancer progression. However, the biological functions of SNHG7 in the colorectal cancer (CRC) remained to be almost unknown. The current in silico study was aimed to find the potential role of SNHG7 in the CRC development. In this study, we showed the up-regulation of SNHG7 as well as its potential correlation with miRNAs, including mir-193a-5p and mir-485-5P. We hypothesized that SNHG7 modulates these miRNAs availability by acting as a molecular sponge. Our findings showed the potential targets of these miRNAs by studying different databases as well as in silico analyses. In summary, we found SNHG7 as a potential ceRNA which may be a promising biomarker for diagnostic and therapeutic target in CRC.

Up-frameshift Protein 1 Promotes Tumor Progression by Regulating Apoptosis and Epithelial-Mesenchymal Transition of Colorectal Cancer.

Background: Recently, accumulating evidence confirmed that up-frameshift protein 1 (UPF1) was aberrantly expressed in various cancers. However, the molecular mechanism mediated by UPF1 underlying colorectal carcinogenesis remains unclear. Method: Immunohistochemistry (IHC) and quantitative real-time polymerase chain reaction analysis were used to determine the expression level of UPF1 in colorectal cancer (CRC) tissues. CCK-8, EdU, transwell assay, and flow cytometry were performed to investigate the biological significance of UPF1. Epithelial–mesenchymal transition (EMT) and apoptosis associated markers were detected by western blotting. Results: We found that UPF1 expression was upregulated in CRC tissues and cell lines. Clinical analysis revealed that high UPF1 expression was positively correlated with advanced stage, lymph node metastasis and shorter survival. Knockdown of UPF1 suppressed cell proliferation and cell cycle progression. Functionally, UPF1 promotes tumor metastasis by inducing epithelial to mesenchymal transition. Further investigations revealed that knockdown of UPF1 promoted apoptosis through triggering DNA damage. Conclusions: Taken together, this research revealed that UPF1 plays an oncogenic role in CRC via regulating EMT and apoptosis and may be a potential therapeutic target for CRC.

Long non-coding RNA BCYRN1 exerts an oncogenic role in colorectal cancer by regulating the miR-204-3p/KRAS axis

BackgroundIt has been well documented that long non-coding RNAs (lncRNAs) regulate numerous characteristics of cancer, including proliferation, migration, metastasis, apoptosis, and even metabolism. LncRNA BCYRN1 (BCYRN1) is a newly identified brain cytoplasmic lncRNA with 200 nucleotides that was discovered to be highly expressed in tumour tissues, including those of hepatocellular carcinoma, gastric cancer and lung cancer. However, the roles of BCYRN1 in colorectal cancer (CRC) remain obscure. This study was designed to reveal the role of BCYRN1 in the occurrence and progression of CRC.MethodsRT-PCR was used to detect the expression level of BCYRN1 in tumour tissues and CRC cell lines. BCYRN1 was knocked down in CRC cells, and cell proliferation changes were evaluated by cell counting kit-8 (CCK-8), 5-ethynyl-2′-deoxyuridine (EdU), and Ki-67 and proliferating cell nuclear antigen (PCNA) expression assays. Cell migration and invasion changes were evaluated by wound healing, Transwell and invasion-related protein expression assays. Flow cytometry analysis was used to assess whether BCYRN1 regulates the apoptosis of CRC cells. The dual luciferase reporter gene detects the competitive binding of BCYRN1 to miR-204-3p. In vivo experiments were performed to evaluate the effect of BCYRN1 on tumour development. TargetScan analysis and dual luciferase reporter gene assays were applied to detect the target gene of miR-204-3p. Rescue experiments verified that BCYRN1 affects CRC by regulating the effect of miR-204-3p on KRAS.ResultsWe found that compared with normal tissues and human intestinal epithelial cells (HIECs), CRC tumour tissues and cell lines had significantly increased BCYRN1 levels. We further determined that knockdown of BCYRN1 inhibited the proliferation, migration, and invasion and promoted the apoptosis of CRC cells. In addition, bioinformatics analysis and dual luciferase reporter assay showed that BCYRN1 served as a competitive endogenous RNA (ceRNA) to regulate the development of CRC through competitively binding to miR-204-3p. Further studies proved that overexpression of miR-204-3p reversed the effects of BCYRN1 on CRC. Next, TargetScan analysis and dual luciferase reporter assay indicated that KRAS is a target gene of miR-204-3p and is negatively regulated by miR-204-3p. A series of rescue experiments showed that BCYRN1 affected the occurrence and development of CRC by regulating the effects of miR-204-3p on KRAS. In addition, tumorigenesis experiments in a CRC mouse model confirmed that BCYRN1 downregulation effectively inhibited tumour growth.ConclusionsOur findings suggest that BCYRN1 plays a carcinogenic role in CRC by regulating the miR-204-3p/KRAS axis.

Circular RNA NOX4 promotes the development of colorectal cancer via the microRNA‑485‑5p/CKS1B axis.

Colorectal cancer (CRC) is a common malignancy globally. The aim of the present study was to explore the role and the working mechanism of circular RNA NADPH oxidase 4 (circNOX4; circBase ID, hsa_circ_0023990) in CRC. Reverse transcription-quantitative (RT-q)PCR was used to examine the expression of circNOX4, NOX4 mRNA and microRNA (miR)-485-5p in CRC tissues and cell lines. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and Transwell assays were performed to analyze CRC cell viability and motility. The glycolytic ability of CRC cells was assessed by measuring glucose consumption, lactate production, extracellular acidification and O2 consumption rates using commercial kits. The starBase database was used to predict the targets of circNOX4 and miR-485-5p, and the interaction was confirmed by dual-luciferase reporter and RNA immunoprecipitation assays. A murine xenograft model was established to verify the role of circNOX4 in CRC in vivo. The results demonstrated that the expression of circNOX4 was upregulated in CRC tissues and cell lines compared with that in adjacent normal tissues and a normal colon epithelial cell line, respectively. The expression of circNOX4 was negatively associated with the prognosis of patients with CRC. CircNOX4 silencing suppressed the proliferation, migration, invasion and glycolysis of CRC cells. miR-485-5p was identified as a target of circNOX4. CircNOX4 promoted CRC progression by sponging miR-485-5p. miR-485-5p was demonstrated to bind to the 3′ untranslated region (UTR) of CDC28 protein kinase regulatory subunit 1B (CKS1B). miR-485-5p overexpression-mediated malignant properties of CRC cells were partly reversed by the transfection with the CKS1B overexpression plasmid. CircNOX4 silencing restrained the CRC xenograft growth in vivo. Collectively, the results of the present study demonstrated that circNOX4 may serve an oncogenic role in CRC by promoting the proliferation, migration, invasion and glycolysis of CRC cells via the miR-485-5p/CKS1B axis.

PDCD6 cooperates with C-Raf to facilitate colorectal cancer progression via Raf/MEK/ERK activation

BackgroundColorectal cancer (CRC) is one of the most common malignancies, and it’s expected that the CRC burden will substantially increase in the next two decades. New biomarkers for targeted treatment and associated molecular mechanism of tumorigenesis remain to be explored. In this study, we investigated whether PDCD6 plays an oncogenic role in colorectal cancer and its underlying mechanism.MethodsProgrammed cell death protein 6 (PDCD6) expression in CRC samples were analyzed by immunohistochemistry and immunofluorescence. The prognosis between PDCD6 and clinical features were analyzed. The roles of PDCD6 in cellular proliferation and tumor growth were measured by using CCK8, colony formation, and tumor xenograft in nude mice. RNA-sequence (RNA-seq), Mass Spectrum (MS), Co-Immunoprecipitation (Co-IP) and Western blot were utilized to investigate the mechanism of tumor progression. Immunohistochemistry (IHC) and quantitative real-time PCR (qRT-PCR) were performed to determine the correlation of PDCD6 and MAPK pathway.ResultsHigher expression levels of PDCD6 in tumor tissues were associated with a poorer prognosis in patients with CRC. Furthermore, PDCD6 increased cell proliferation in vitro and tumor growth in vivo. Mechanistically, RNA-seq showed that PDCD6 could affect the activation of the MAPK signaling pathway. PDCD6 interacted with c-Raf, resulting in the activation of downstream c-Raf/MEK/ERK pathway and the upregulation of core cell proliferation genes such as MYC and JUN.ConclusionsThese findings reveal the oncogenic effect of PDCD6 in CRC by activating c-Raf/MEK/ERK pathway and indicate that PDCD6 might be a potential prognostic indicator and therapeutic target for patients with colorectal cancer.