Expression Of CCAT1 Research Articles

Tectorigenin Inhibits Glycolysis-induced Cell Growth and Proliferation by Modulating LncRNA CCAT2/miR-145 Pathway in Colorectal Cancer.

Colorectal cancer (CRC) places a heavy burden on global health. Tectorigenin (Tec) is a type of flavonoid-based compound obtained from the Chinese medical herb Leopard Lily Rhizome. It was found to exhibit remarkable anti-tumor properties in previous studies. However, the effect and molecular mechanisms of Tec in colorectal cancer have not been reported. The objective of this study was to explore the action of Tec in proliferation and glycolysis in CRC and the potential mechanism with regard to the long non-coding RNA (lncRNA) CCAT2/micro RNA-145(miR-145) pathway in vitro and in vivo . The anti-tumor effect of Tec in CRC was examined in cell and animal studies, applying Cell Counting Kit-8 (CCK-8) assay as well as xenograft model experiments. Assay kits were utilized to detect glucose consumption and lactate production in the supernatant of cells and animal serum. The expression of the glycolysis-related proteins was assessed by Western Blotting, and levels of lncRNA CCAT2 and miR-145 in CRC tissue specimens and cells were assessed by realtime quantitative PCR (RT-qPCR). Tec significantly suppressed cell glycolysis and proliferative rate in CRC cells. It could decrease lncRNA CCAT2 in CRC cells but increase the expression of miR-145. LncRNA CCAT2 overexpression or inhibition of miR-145 could abolish the inhibitive effects of Tec on the proliferation and glycolysis of CRC cells. The miR-145 mimic rescued the increased cell viability and glycolysis levels caused by lncRNA CCAT2 overexpression. Tec significantly inhibited the growth and glycolysis of CRC xenograft tumor. The expression of lncRNA CCAT2 decreased while the expression of miR-145 increased after Tec treatment in vivo. Tec can inhibit the proliferation and glycolysis of CRC cells through the lncRNA CCAT2/miR-145 axis. Altogether, the potential targets discovered in this research are of great significance for CRC treatment and new drug development.

LncRNA CCAT1 knockdown suppresses tongue squamous cell carcinoma progression by inhibiting the ubiquitination of PHLPP2.

Tongue squamous cell carcinoma (TSCC) is prevailing malignancy in the oral and maxillofacial region, characterized by its high frequency. LncRNA CCAT1 can promote tumorigenesis and progression in many cancers. Here, we investigated the regulatory mechanism by which CCAT1 influences growth and metastasis of TSCC. Levels of CCAT1, WTAP, TRIM46, PHLPP2, AKT, p-AKT, and Ki67 in TSCC tissues and cells were assessed utilizing qRT-PCR, Western blot and IHC. Cell proliferation, migration, and invasion were evaluated utilizing CCK8, colony formation, wound healing and transwell assays. Subcellular localization of CCAT1 was detected utilizing FISH assay. m6A level of CCAT1 was assessed using MeRIP. RNA immunoprecipitation (RIP), Co-immunoprecipitation (Co-IP) and RNA pull down elucidated binding relationship between molecules. Nude mouse tumorigenesis experiments were used to verify the TSCC regulatory function of CCAT1 in vivo. Metastatic pulmonary nodules were observed utilizing hematoxylin and eosin (HE) staining. CCAT1 silencing repressed TSCC cell proliferation, migration and invasion. Expression of CCAT1 was enhanced through N6-methyladenosine (m6A) modification of its RNA, facilitated by WTAP. Moreover, IGF2BP1 up-regulated CCAT1 expression by stabilizing its RNA transcript. CCAT1 bond to PHLPP2, inducing its ubiquitination and activating AKT signaling. CCAT1 mediated the ubiquitination and degradation of PHLPP2 by TRIM46, thereby promoting TSCC growth and metastasis. CCAT1/TRIM46/PHLPP2 axis regulated proliferation and invasion of TSCC cells, implying that CCAT1 would be a novel therapeutic target for TSCC patients.

Long non-coding RNA CCAT1 acts as an oncogene to promote radiation resistance in lung adenocarcinoma: an epigenomics-based investigation.

Long non-coding RNAs (lncRNAs) appear to be the crucial modulators in various processes and critically influence the oncogenesis. As one of the LncRNAs, LncRNA CCAT1 has been reported to be closely associated with the progression multiple cancers, but its role in modulating the radioresistance of lung adenocarcinoma (LUAD) remains unclear. In our present study, we screened the potential radioresistance related LncRNAs in LUAD based on the data from The Cancer Genome Atlas (TCGA) database. Data suggested that CCAT1 was abundantly expressed in LUAD and CCAT1 was significantly associated with poor prognosis and radioresistance. Moreover, our in vitro experiments showed that radiation treatment could trigger elevated expression of CCAT1 in the human LUAD cell lines. Further loss/gain-of-function investigations indicated that CCAT1 knockdown significantly inhibited cell proliferation, migration and promoted cell apoptosis in NCI-H1299 cells under irradiation, whereas CCAT1 overexpression in A549 cells yield the opposite effects. In summary, we identified the promoting role of CCAT1 in radioresistance of LUAD, which may provide a theoretical basis for radiotherapy sensitization of LUAD.

Long non-coding RNAs CCAT1 and CCAT2 in colorectal liver metastases are tumor-suppressive via MYC interaction and might predict patient outcomes.

Liver metastases severely reduce the long term survival of colorectal cancer patients. Long non-coding RNAs (lncRNAs) CCAT1 and CCAT2 have previously been found to be associated with impaired patient outcomes in primary colorectal cancer. We aimed to elucidate the role of CCAT1 and CCAT2 in colorectal liver metastases. Total RNA was isolated from 97 human tissue samples of colorectal liver metastases and adjacent normal liver tissue. Gene expression analysis was performed by RT-qPCR and Multiplex ELISA and correlated with patient characteristics and survival. Gene expression, cancer cell migration, invasion, and proliferation were studied after siRNA-mediated knockdown of CCAT1, CCAT2, and MYC in metastatic colorectal cancer cell lines Colo205 and HROC277Met2. Elevated expression levels of lncRNAs CCAT1 and CCAT2, and their common target MYC in colorectal liver metastases were associated with prolonged progression-free survival after liver resection. High expression of CCAT1 was likewise associated with prolonged overall survival. Knockdown of CCAT1, CCAT2, and MYC resulted in increased migratory and invasive potential in metastatic colorectal cancer cell lines. Gene expression analysis revealed alterations in constituents of Wnt signaling following knockdown. Our findings demonstrate tumor-suppressive functions of lncRNAs CCAT1 and CCAT2 in colorectal liver metastases. They suppress Wnt signaling directly and indirectly through target gene MYC and might prevent further metastatic spread from colorectal liver metastases.

Transcription factor B-MYB activates lncRNA CCAT1 and upregulates SOCS3 to promote chemoresistance in colorectal cancer

Currently, resistance to oxaliplatin (OXA) has become an important obstacle to improving the clinical outcome of patients with colorectal cancer (CRC). Moreover, long non-coding RNAs (lncRNAs) have been documented in cancer chemoresistance, and our bioinformatic analysis suggested an involvement of lncRNA CCAT1 in CRC development. In this context, this study aimed to clarify the upstream and downstream mechanisms underpinning the effect of CCAT1 in the resistance of CRC to OXA. The expression of CCAT1 and the upstream B-MYB in the CRC samples was predicted by bioinformatics analysis and then verified using RT-qPCR in CRC cell lines. Accordingly, overexpression of B-MYB and CCAT1 was observed in CRC cells. SW480 cell line was used for the construction of OXA-resistant cell line (SW480R). Ectopic expression and knockdown experiments of B-MYB and CCAT1 were conducted in SW480R cells to delineate their roles in the malignant phenotypes and half-maximal (50%) inhibitory concentration (IC50) of OXA. It was found that CCAT1 promoted the resistance of CRC cells to OXA. Mechanistically, B-MYB transcriptionally activated CCAT1, which recruited DNMT1 to inhibit SOCS3 expression through elevating the SOCS3 promoter methylation. By this mechanism, the resistance of CRC cells to OXA was enhanced. Meanwhile, these in vitro findings were reproduced in vivo on xenografts of SW480R cells in nude mice. To sum up, B-MYB might promote the chemoresistance of CRC cells to OXA via regulating the CCAT1/DNMT1/SOCS3 axis.

LncRNA-CCAT2 Reduces the Drug Resistance of Ovarian Cancer Cells

This study assesses lncRNA-CCAT2’s role in reducing the drug resistance of ovarian cancer cell lines. Cisplatin-resistant SKOV-3/DDP cells were established and assigned into CC group (transfected with lncRNA CCAT2 siRNA-NC) and CA group (transfected with lncRNA CCAT2 siRNA) followed by analysis of cell proliferation, apoptosis, expression of CCAT2, ERK1/2, Sp1 and relationship between CCAT2 and ERK1/2 and Sp1. CCAT2 expression in SKOV-3/DDP was higher than IOSE80 and SKOV-3 (P < 0.001). ERK1/2 expression in SKOV-3 and SKOV-3/DDP was 0.67±0.09, 1.97±0.40 (t = 14.18, P < 0.001). Sp1 level in SKOV-3 and SKOV-3/DDP was 0.49±0.05, 1.07±0.11 (P = 21.47, P < 0.001). Transfection of CCAT2 reduced cell fluorescence activity of ERK1/2 and Sp1 (P < 0.001). Cell proliferation in CC group and CA group had no difference at 0 h (P > 0.001) and the inhibition of cell proliferation was found at 24 h (P < 0.001). CC group (5.13±0.51) had lower cell apoptosis rate than CA group (20.52±2.24) (t = 29.96, P < 0.001) but higher ERK1/2 and Sp1 protein level CC group than CA group (P < 0.001). In conclusion, transfection of lncRNA-CCAT2 inhibits SKOV-3/DDP proliferation by targeting ERK1/2-Sp1 signaling pathway, promotes apoptosis and reduces drug resistance.

Expression analysis of Wnt signaling pathway related lncRNAs in periodontitis: A pilot case-control study

LncRNAs are involved in the modulation of several signaling pathways which have a crucial effect in the differentiation of periodontal ligament cells and the induction of cementum regeneration. Autophagy and Wnt signaling are two important pathways with a wide range of interrelationships associated with periodontitis. We chose four lncRNAs based on their potential interaction with these two pathways. We examined the expression of FOXD2-AS1, NNT-AS1, GAS8-AS1, and CCAT1 lncRNAs in tissues and blood specimens of patients with periodontitis and unaffected controls using qRT-PCR. Expression amounts of FOXD2-AS1 were lower in blood of cases compared with controls (relative expression (RE) = 0.08, P value<0.001). Tissue expression of FOXD2-AS1 was similar between cases and controls. Difference in blood levels of FOXD2-AS1 was significant among female subjects (RE = 0.07, P-value = 0.01), but not among male subjects. In addition, we reported lower levels of NNT-AS1 in blood samples of cases versus controls (RE = 0.25, P value = 0.05). But such a pattern was not seen in tissue samples. Expression of GAS8-AS1 was lower in both tissue and blood specimens of patients compared with control (RE = 0.49, P value = 0.02 and RE = 0.32, P value = 0.03 for tissue and blood specimens, respectively). Moreover, the differences in blood expression of GAS8-AS1 were significant in female patients compared with female controls (RE = 0.25, P-value = 0.04). Expression of CCAT1 was significantly lower in both gingival tissue and blood samples of patients compared with control (RE for tissue samples = 0.36, P-value = 0.02 and RE for blood samples = 0.33, P-value = 0.02). This pattern of expression was also detected in tissue specimens obtained from male persons (RE = 0.23, P value = 0.02) and blood samples acquired from female patients compared with corresponding control samples (RE = 0.21, P value<0.001). FOXD2-AS1 showed the best AUC values for distinguishing periodontitis in blood samples (AUC = 0.78). Combination of transcript levels of all four lncRNAs increased the diagnostic power to 0.81 and 0.74 in the gingival tissues and blood specimens, respectively. Our study demonstrates dysregulation of several lncRNAs in the periodontitis. These transcripts might partake in the pathogenesis of periodontitis and could have a possible correlation with autophagy and Wnt signaling pathways.

The association of clinicopathological characterizations of colorectal cancer with membrane-bound mucins genes and LncRNAs

BackgroundColorectal cancer (CRC) is one of the most common malignancies in the world and has a high mortality rate. It is believed that dysfunction in the expression of mucins and aberrant expression of some lncRNAs are associated with the occurrence and development of CRC. Therefore, the aim of the present study was to investigate the expression of MUC15, MUC16, MUC20, PCAT1, CCAT1 and HOTAIR genes in colorectal cancer and its relationship with clinicopathological variables. Materials and methodsThis research was prospective case-control study. Tumors from CRC patients were collected from the Taleghani Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran. RNA extraction and cDNA synthesis were performed using the corresponding kits. The gene primer was designed and RT-PCR was used to evaluate gene expression. The t-test and ANOVA were employed to examine the differences between groups. Data analysis was performed using Prism8 software. ResultsThe results of the present study showed that the expression of MUC15 (P = 0.0012), MUC20 (P = 0.009) and CCAT1 (P = 0.001) genes in patients with colorectal cancer were significantly different from tumor margin samples. There were also associations between the expression of the studied genes and clinicopathological variables such as grade and stage of colorectal cancer tumor as well as the age of the patients. The area under the curves (AUC) for the MUC15 0.953 (95% CI 7565–0.9897, P = 0.0003), MUC20 0.782 (95% CI 0.6163–0.9482, P = 0.008) and CCAT1 0.917 (95% CI 0.8015–1, P = 0.0003) were calculated by ROC analysis. ConclusionThe current experiment revealed changes in expression level of mucin genes and lncRNAs in CRC and its different stages, showing that they can be considered as biomarkers for diagnosis of this cancer.

LncRNA CCAT1 facilitates the proliferation, invasion and migration of human laryngeal squamous cell carcinoma cells via the miR-218-5p/BMI1.

Long non-coding RNAs (LncRNAs) are vital in the treatment of laryngeal squamous cell carcinoma (LSCC). This study estimated the mechanism of lncRNA CCAT1 (CCAT1) in LSCC cells. The expression of CCAT1 in the human laryngeal mucosal epithelial cells (HLCs) and LSCC cells (Hep-2 and TU177) was detected. CCK-8 and Transwell assays were used to evaluate the cell proliferative, migrative, and invasive abilities, respectively. The subcellular localization of CCAT1 was verified by RNA-FISH and cytoplasmic isolation assays. The targeted relationship among CCAT1, miR-218-5p, and BMI1 was verified by dual-luciferase assay. Expressions of miR-218-5p and BMI1 were detected by RT-qPCR. Our results depicted that CCAT1 was highly-expressed in Hep-2 and TU177 cells. Silencing CCAT1 inhibited the proliferation, migration, and invasion of Hep-2 and TU177 cells. Mechanically, CCAT1 regulated the BMI1 expression by competitively binding to miR-218-5p as a competing endogenous RNA (ceRNA), and thus facilitated the growth of Hep-2 and TU177 cells. Downregulation of miR-218-5p or upregulation of BMI1 inhibited the inhibitory effect of silencing CCAT1 on Hep-2 and TU177 cell proliferation, invasion, and migration. In conclusion, our study elicited that lncRNA CCAT1 facilitated the proliferation, migration, and invasion of Hep-2 and TU177 cells by sponging miR-218-5p and regulating the downstream BMI1.

Contribution of Long Non-Coding Rnas (Ccat1, Malat1, and Pandar) in the Pathogenesis of Colorectal Cancer

Objectives: To assess the relationship between the expression of long non-coding RNAs (lncRNAs), CCAT1, MALAT1, and PANDAR, in CRC patients with varying physical, environmental, and pathophysiological factors. Material and Methods: A case-control study was conducted at King Abdulaziz University (Jeddah, Saudi Arabia). Whole blood was collected from 63 CRC patients and 40 healthy subjects in the period from January to August 2016. Anthropometric measurements were taken and the total RNA was isolated and the expression of lncRNA was determined by real-time polymerase chain reaction. Various software programs, including REST2009 and GraphPad Prism version 7, were used to analyze the different statistical correlations. Results: MALAT1 was significantly highly expressed in CRC female patients, whereas CCAT1 and PANDAR were significantly up-regulated in male CRC patients, as compared with controls. Moreover, in obese CRC patients, CCAT1, MALAT1, and PANDAR expressions were significantly up-regulated, while in overweight CRC patients, only MALAT1 was significantly more highly expressed, compared to controls. There was a slight increase in PANDAR expression in high-grade CRC patients, compared to low-grade patients. Finally, CCAT1 was significantly up-regulated in high fish intake CRC patients and was significantly correlated with smoking status. Conclusion: LncRNAs may contribute to CRC pathogenesis by affecting several physical and environmental factors. Keywords: Colorectal cancer, LncRNA CCAT1, LncRNA MALAT1, LncRNA PANDAR

Colorectal cancer risk variant rs7017386 modulates two oncogenic lncRNAs expression via ATF1-mediated long-range chromatin loop.

The activating transcription factor 1 (ATF1) has been identified as a vital pathogenic factor in the progression of colorectal cancer (CRC), whiles, the precise regulatory mechanisms remain elusive. Here, we comprehensively characterized the ATF1 cistrome by RNA-seq and ChIP-seq assays in CRC cell lines. As the results, we identified 358 genes differentially regulated and 15,029 ATF1 binding sites and demonstrated that ATF1 was widely involved in major signaling pathways in CRC, such as Wnt, TNF, Jak-STAT. Subsequently, by the expression quantitative trait loci (eQTL) analyses, we found that rs7017386 was associated with the expression of CCAT1 and PVT1 in the Wnt pathway. By a two-stage population study with 6,131 CRC cases and 10,022 healthy controls, we identified the variant was associated with CRC risk. Mechanistically, we found rs7017386 allele-specifically enhanced the binding affinity of ATF1 and promoted the expressions of PVT1 and CCAT1, via forming a long-range chromatin loop. Moreover, those two lncRNAs could synergistically facilitate c-Myc expression to activate the Wnt pathway in CRC progression. Our findings not only demonstrated the transcriptomic profiling of ATF1 in CRC, but also provided important clues for the etiology of CRC.

LncRNA CCAT1 Upregulates ATG5 to Enhance Autophagy and Promote Gastric Cancer Development by Absorbing miR-140-3p.

Long noncoding RNA colon cancer-associated transcript 1 (LncRNA CCAT1) is highly expressed in gastric cancer tissues and plays a role in autophagy. However, the underlying mechanism still needs to be further clarified. To study the role of LncRNA CCAT1 in regulating autophagy of gastric cancer cells, analyze its downstream targets, and elucidate the mechanism. qPCR detected the expression of LncRNA CCAT1 in gastric cancer cells. The proliferation, migration, and invasion ability of LncRNA CCAT1 and the expression level of autophagy-related proteins in gastric cancer cells were detected. Bioinformatics method predicted the downstream targets of LncRNA CCAT1, and they were verified by dual-luciferase assay. The relationship between LncRNA CCAT1, miR-140, and ATG5 was verified by co-transfection, and the expression levels of ATG5 and ATG5-ATG12 complex proteins were detected. Finally, the role of LncRNA CCAT1 in vivo was confirmed by gastric cancer transplantation model. LncRNA CCAT1 was highly expressed in gastric cancer cells. LncRNA CCAT1 can promote the proliferation, migration, invasion, and autophagy activity of gastric cancer cells. LncRNA CCAT1 can bind to miR-140-3p and regulate its expression, while miR-140-3p further regulates the expression of ATG5. Overexpression of LncRNA CCAT1 can promote tumor growth in nude mice. After LncRNA CCAT1 silencing, the positive expression rate of ATG5 in nude mice was low. LncRNA CCAT1 may inhibit the expression of miR-140-3p by sponge adsorption, thus weakening its inhibitory effect on ATG5. Eventually, gastric cancer cells were more prone to autophagy under the pressure of stress.

Altered expression of CCAT1 and CCAT2 lncRNAs in autism spectrum disorder

Long non-coding RNAs (lncRNAs) have been proposed as important contributors in the development of brain and in the pathobiology of neurodevelopmental disorders. Altered levels of a number of lncRNAs in the circulation have been linked with the pathogenesis of autism spectrum disorder (ASD). We measured expression of Colon Cancer Associated Transcripts 1 and 2 (CCAT1 and CCAT2) in the circulation of ASD cases and healthy children. Expression of CCAT1 was remarkably lower in ASD children than in healthy children (Posterior Beta = −0.682, SE = 0.35, adjusted P value = 0.022). Conversely, expression of CCAT2 was higher in ASD cases compared with controls (Posterior Beta = 2.237, standard error (SE) = 0.38, adjusted P value<0.0001). Subsequently, we compared expressions of CCAT1 and CCAT2 between males and females demonstrating no substantial difference in their expression between these two groups (P values = 0.209 and 0.231, respectively). The interaction between group and gender was insignificant for both lncRNAs (P values = 0.951 and 0.482, respectively). While CCAT1 expression was not different among age-based subgroups, CCAT2 expression was significantly lower in healthy children age between 5 and 6 years compared with the other groups of healthy children. CCAT1 could differentiate between these two groups with area under curve (AUC) = 0.663, P value = 0.016, sensitivity = 54.33% and specificity = 82.93%. Diagnostic power of CCAT2 was superior to CCAT1 as revealed by AUC = 0.779, P value<0.0001, sensitivity = 86.67% and specificity = 73.17%. Taken together, CCAT1 and CCAT2 are suggested as candidate for functional studies in ASD.

Anti-oncogenic effects of SOX2 silencing on hepatocellular carcinoma achieved by upregulating miR-222-5p-dependent CYLD via the long noncoding RNA CCAT1

In this study, we determined the involvement of SOX2 and its downstream signaling molecules in hepatocellular carcinoma (HCC) progression. We carried out lentiviral transfection in HepG2 cells to determine the roles of SOX2, CCAT1, EGFR, miR-222-5p, and CYLD in HepG2 cells. We first determined the interaction between SOX2 and CCAT1 and that between miR-222-5p and CYLD and their effect on tumor growth in vivo was analyzed in HCC-xenograft bearing nude mice xenografts. SOX2 and CCAT1 were highly expressed in HCC tissues and HepG2 cells. SOX2 bound to the regulatory site of CCAT1. Silencing of SOX2 or CCAT1 inhibited HepG2 cell proliferation, migration, and invasion as well as decreased the expression of CCAT1 and EGFR. CCAT1 silencing reduced EGFR expression, but EGFR expression was increased in HCC tissues and HepG2 cells, which promoted proliferation, migration, and invasion in vitro. EGFR upregulated miR-222-5p, leading to downregulation of CYLD. miR-222-5p inhibition or CYLD overexpression repressed cell functions in HepG2 cells. SOX2 silencing decreased CCAT1, EGFR, and miR-222-5p expression but increased CYLD expression. Loss of SOX2 also reduced the growth rate of tumor xenografts. In summary, SOX2-mediated HCC progression through an axis involving CCAT1, EGFR, and miR-222-5p upregulation and CYLD downregulation.

Effect of rs67085638 in long non‐coding RNA (CCAT1) on colon cancer chemoresistance to paclitaxel through modulating the microRNA‐24‐3p and FSCN1

It has been reported that rs67085638 in long non‐coding RNAs (lncRNA)‐CCAT1 was associated with the risk of tumorigenesis. Also, CCAT1 could affect chemoresistance of cancer cells to paclitaxel (PTX) via regulating miR‐24‐3p and FSCN1 expression. In this study, we aimed to investigate the effect of rs67085638 on the expression of CCAT1/miR‐24‐3p/FSCN1 and the response of colon cancer to the treatment of PTX. 48 colon cancer patients were recruited and grouped by their genotypes of rs67085638 polymorphism as a CC group (N = 28) and a CT group (N = 20). PCR analysis, IHC assay and Western blot, TUNEL assay and flow cytometry were conducted. LncRNA‐CCAT1 and FSCN1 mRNA/protein were overexpressed, whereas miR‐24‐3p was down‐regulated in the CT‐genotyped patients and cells compared with those in the CC‐genotyped patients and cells. The survival of colon cancer cells was decreased, whereas the apoptosis of colon cancer cells was increased by PTX treatment in a dose‐dependent manner. MiR‐24‐3p was validated to target lncRNA‐CCAT1 and FSCN1 mRNA, and the overexpression of CCAT1 could reduce the expression of miR‐24‐3p although elevating the expression of FSCN1. Knockdown of lncRNA‐CCAT1 partly reversed the suppressed growth of CT‐genotyped tumours. And the knockdown of lncRNA‐CCAT1 partly reversed the dysregulation of lncRNA‐CCAT1 and FSCN1 mRNA/protein in rs67085638‐CT + NC shRNA mice. The findings of this study demonstrated that the presence of the minor allele of rs67085638 increased the expression of CCAT1 and accordingly enhanced the resistance to PTX. Down‐regulation of CCAT1 significantly re‐stored the sensitivity to PTX of colon cancer cells.

Enhancer-derived long non-coding RNAs CCAT1 and CCAT2 at rs6983267 has limited predictability for early stage colorectal carcinoma metastasis

Up-regulation of long non-coding RNAs (lncRNAs), colon-cancer associated transcript (CCAT) 1 and 2, was associated with worse prognosis in colorectal cancer (CRC). Nevertheless, their role in predicting metastasis in early-stage CRC is unclear. We measured the expression of CCAT1, CCAT2 and their oncotarget, c-Myc, in 150 matched mucosa-tumour samples of early-stage microsatellite-stable Chinese CRC patients with definitive metastasis status by multiplex real-time RT-PCR assay. Expression of CCAT1, CCAT2 and c-Myc were significantly up-regulated in the tumours compared to matched mucosa (p < 0.0001). The expression of c-Myc in the tumours was significantly correlated to time to metastasis [hazard ratio = 1.47 (1.10–1.97)] and the risk genotype (GG) of rs6983267, located within CCAT2. Expression of c-Myc and CCAT2 in the tumour were also significantly up-regulated in metastasis-positive compared to metastasis-negative patients (p = 0.009 and p = 0.04 respectively). Nevertheless, integrating the expression of CCAT1 and CCAT2 by the Random Forest classifier did not improve the predictive values of ColoMet19, the mRNA-based predictor for metastasis previously developed on the same series of tumours. The role of these two lncRNAs is probably mitigated via their oncotarget, c-Myc, which was not ranked high enough previously to be included in ColoMet19.

The Long Noncoding RNA CCAT2 Induces Chromosomal Instability Through BOP1-AURKB Signaling

Chromosomal instability (CIN) is a carcinogenesis event that promotes metastasis and resistance to therapy by unclear mechanisms. Expression of the colon cancer-associated transcript 2 gene (CCAT2), which encodes a long noncoding RNA (lncRNA), associates with CIN, but little is known about how CCAT2 lncRNA regulates this cancer enabling characteristic. We performed cytogenetic analysis of colorectal cancer (CRC) cell lines (HCT116, KM12C/SM, and HT29) overexpressing CCAT2 and colon organoids from C57BL/6N mice with the CCAT2 transgene and without (controls). CRC cells were also analyzed by immunofluorescence microscopy, γ-H2AX, and senescence assays. CCAT2 transgene and control mice were given azoxymethane and dextran sulfate sodium to induce colon tumors. We performed gene expression array and mass spectrometry to detect downstream targets of CCAT2 lncRNA. We characterized interactions between CCAT2 with downstream proteins using MS2 pull-down, RNA immunoprecipitation, and selective 2'-hydroxyl acylation analyzed by primer extension analyses. Downstream proteins were overexpressed in CRC cells and analyzed for CIN. Gene expression levels were measured in CRC and non-tumor tissues from 5 cohorts, comprising more than 900 patients. High expression of CCAT2 induced CIN in CRC cell lines and increased resistance to 5-fluorouracil and oxaliplatin. Mice that expressed the CCAT2 transgene developed chromosome abnormalities, and colon organoids derived from crypt cells of these mice had a higher percentage of chromosome abnormalities compared with organoids from control mice. The transgenic mice given azoxymethane and dextran sulfate sodium developed more and larger colon polyps than control mice given these agents. Microarray analysis and mass spectrometry indicated that expression of CCAT2 increased expression of genes involved in ribosome biogenesis and protein synthesis. CCAT2 lncRNA interacted directly with and stabilized BOP1 ribosomal biogenesis factor (BOP1). CCAT2 also increased expression of MYC, which activated expression of BOP1. Overexpression of BOP1 in CRC cell lines resulted in chromosomal missegregation errors, and increased colony formation, and invasiveness, whereas BOP1 knockdown reduced viability. BOP1 promoted CIN by increasing the active form of aurora kinase B, which regulates chromosomal segregation. BOP1 was overexpressed in polyp tissues from CCAT2 transgenic mice compared with healthy tissue. CCAT2 lncRNA and BOP1 mRNA or protein were all increased in microsatellite stable tumors (characterized by CIN), but not in tumors with microsatellite instability compared with nontumor tissues. Increased levels of CCAT2 lncRNA and BOP1 mRNA correlated with each other and with shorter survival times of patients. We found that overexpression of CCAT2 in colon cells promotes CIN and carcinogenesis by stabilizing and inducing expression of BOP1 an activator of aurora kinase B. Strategies to target this pathway might be developed for treatment of patients with microsatellite stable colorectal tumors.

Long non-coding RNA CCAT2 as a potential serum biomarker for diagnosis and prognosis of multiple myeloma.

Increasing knowledge of long non-coding RNAs (lncRNAs) has shown that they can be used as circulating tumor markers. Also, considerable evidences have revealed that lncRNAs have important roles in tumor diagnosis and prognosis. The lncRNA CCAT2 has manifested its carcinogenic effect in a variety of tumors, but the serum expression level and clinical value in multiple myeloma (MM) remain to be explored. In our study, the expression of lncRNA CCAT2 is upregulated in the serum and bone marrow of MM patients by using quantitative real-time polymerase chain reaction (qRT-PCR). The high expression level of CCAT2 in the serum of MM patients correlated with International Scoring System (ISS) stages, renal dysfunction, serum β2-microglobulin (β2-MG) concentration, and light chain (κ and λ) concentrations. Area under the curve (AUC) of CCAT2 in serum is 0.899. Besides, the sensitivity and specificity were 85.80% and 83%, respectively. Furthermore, combination of CCAT2, IgA, HGB, and β2-MG significantly improved the MM diagnostic sensitivity and AUC. Here, our present investigation indicates that serum circulating CCAT2 may serve as a potential tumor marker for diagnosis and prognosis of MM.

Long noncoding RNA CCAT1 inhibits miR-613 to promote nonalcoholic fatty liver disease via increasing LXRα transcription.

Nonalcoholic fatty liver disease (NAFLD) is regarded as a threat to public health; however, the pathologic mechanism of NAFLD is not fully understood. We attempted to identify abnormally expressed long noncoding RNA (lncRNAs) and messenger RNA that may affect the occurrence and development of NAFLD in this study. The expression of differentially expressed lncRNAs in NAFLD was determined in oleic acid (OA)-treated L02 cells, and the functions of CCAT1 in lipid droplet formation were evaluated in vitro. Differentially expressed genes (DEGs) were analyzed by microarray analysis, and DEGs related to CCTA1 were selected and verified by weighted correlation network analysis. The dynamic effects of LXRα and CCTA1 on lipid droplet formation and predicted binding was examined. The binding between miR-631 and CCAT1 and LXRα was verified. The dynamic effects of miR-613 inhibition and CCTA1 silencing on lipid droplet formation were examined. The expression and correlations of miR-631, CCAT1, and LXRα were determined in tissue samples. As the results show, CCAT1 was induced by OA and upregulated in NAFLD clinical samples. CCAT1 silencing significantly suppressed lipid droplet accumulation in vitro. LXRα was positively correlated with CCAT1. By inhibiting miR-613, CCAT1 increased the transcription of LXRα and promoted LXRα expression. The expression of LXRα was significantly increased in NAFLD tissues and was positively correlated with CCAT1. In conclusion, CCAT1 increases LXRα transcription by serving as a competing endogenous RNA for miR-613 in an LXRE-dependent manner, thereby promoting lipid droplet formation and NAFLD. CCAT1 and LXRα might be potent targets for NAFLD treatment.

Long non-coding RNA CCAT1 promotes colorectal cancer progression by regulating miR-181a-5p expression.

The vital roles of long noncoding RNAs (lncRNAs) have been implicated in growing number of studies in tumor development. LncRNA CCAT1 has been recognized as associated with tumor development, yet its relation with colorectal cancer (CRC) remains elusive. Our study aimed at elucidating the function and mechanisms of long non-coding RNA CCAT1 in CRC. From a lncRNA profile dataset of 38 pairs of matched tumor-control colon tissues from colorectal patients housed in The Cancer Genome Atlas (TCGA), we detected 10 upregulated and 10 down-regulated lncRNAs in CRC. Fifty cases of CRC patients were enrolled to analyze the correlation between the expression of CCAT1 and clinical pathology. The inverse correlation of expression and target relationship between CCAT1 and miR-181a-5p were verified using qRT-PCR and dual-luciferase reporter gene assay. Cell viability, colony formation ability, aggression and apoptosis were determined by MTT assay, colony formation assay, Transwell and wound healing assays and flow cytometry analysis. Furthermore, Xenograft model was used to show that knockdown of CCAT1 inhibits tumor growth in vivo. The expression of lncRNA CCAT1 was significantly upregulated in CRC tissues. The CCAT1 expression was positively associated with cancer stage (American Joint Committee on Cancer stage, P<0.05). CCAT1 promoted cell proliferation, growth and mobility by targeting miR-181a-5p and the silence of CCAT1 increased the cell apoptosis. Same effect was observed in an in vivo xenograft model, which the tumor size and pro-tumor proteins were significantly diminished by knocking down of CCAT1.