LncRNA CCAT2 promotes the proliferation and metastasis of colorectal cancer through activation of the ERK and Wnt signaling pathways by regulating GNB2 expression.

BACKGROUND: Colorectal cancer (CRC) is a prevalent and lethal tumor, with metastasis being the leading cause of mortality. Previous research has indicated that the long non-coding RNA (lncRNA) CCAT2 is involved in the regulation of various tumor progression mechanisms. However, the precise role of CCAT2 in CRC proliferation and metastasis remains ambiguous. This study seeks to elucidate the mechanisms through which CCAT2 influences CRC. METHODS: High-throughput sequencing and RT-qPCR were used to detect CCAT2 expression in CRC. Functional analyses including CCK8, colony formation, wound healing migration, transwell chamber, and Muse® Cell Analyzer assays were performed to study the effects of CCAT2 gene deletion on CRC cells. RNA-pulldown and protein mass spectrometry were employed to identify the interaction between CCAT2 and GNB2 protein. RESULTS: Increased CCAT2 expression was found in CRC, especially in metastatic CRC. Deletion of CCAT2 gene inhibited CRC cell proliferation, migration, and invasion while promoting apoptosis. The interaction between CCAT2 and GNB2 protein was shown to modulate GNB2 protein alterations and affect the ERK and Wnt signaling pathways, thereby promoting CRC proliferation and metastasis. CONCLUSION: CCAT2 plays a crucial role in CRC progression by modulating the ERK and Wnt signaling pathways through its interaction with GNB2. These findings highlight the importance of CCAT2 as a key regulatory element in the mechanisms underlying CRC proliferation and metastasis.

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

BACKGROUND: 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. OBJECTIVE: 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 . METHODS: 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). RESULTS: 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. CONCLUSION: 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.

Knockdown of Long Noncoding RNA CCAT2 Suppresses Malignant Phenotype in Human Laryngeal Squamous Cell Carcinoma.

This study aimed to explore the biological role and mechanism underlying the effects of colon cancer-associated transcript 2 (CCAT2), a long noncoding RNA (lncRNA) in human laryngeal squamous cell carcinoma (LSCC). CCAT2 expression levels in clinical LSCC samples and TU-212 cell line were evaluated by quantitative real-time PCR. The correlation of CCAT2 expression level with clinical-pathological characteristics of patients and their prognosis was analyzed. The functional role of CCAT2 in human LSCC was assessed by Cell Counting Kit-8, Transwell assay, flow cytometric analysis, and LSCC xenograft experiment in vivo. The expression of potential targeted proteins was detected by Western blotting and immunohistochemistry. We found that expression of CCAT2 was significantly elevated in LSCC tissues and TU-212 cells (p<0.05). Survival analysis showed that LSCC patients with high expression of CCAT2 had a shorter 5-year overall survival rate than those with low expression (p<0.05). In addition, CCAT2 silencing with short hairpin RNA significantly decreased the proliferative and invasive potential of TU-212 cells (p<0.05) and promoted their apoptosis. In Nude mice, CCAT2 knockdown suppressed the growth of tumor and decreased its volume and weight in comparison with the controls (p<0.05). In TU-212 cells, CCAT2 silencing with short hairpin RNA significantly down-regulated the expression of ß-catenin and CDK8 (p<0.05). Thus, knockdown of CCAT2 suppresses proliferation and invasion of the cells and inhibits Wnt/ß-catenin signaling pathway in LSCC, which indicates novel therapeutic targets and prognostic indicators in patients with LSCC.

Evaluating the association of rs6983267 polymorphism of the CCAT2 gene with thyroid cancer susceptibility in the Iranian Azeri population.

Thyroid cancer is the most common malignancy of the endocrine system. LncRNAs play critical role in various cellular processes and are associated with several diseases. CCAT2 is a lncRNA molecule overexpressed in thyroid cancer. Single nucleotide polymorphisms in CCAT2 gene can cause changes in the structure and function of CCAT2 transcripts and susceptibility to several diseases. This study aimed to evaluate the association of rs6983267 in CCAT2 gene with thyroid cancer susceptibility in the Azeri population of Iran. In this "case-control" study, genomic DNA was extracted from peripheral blood of 102 individuals affected by thyroid cancer and 103 healthy individuals as controls. Genotyping was performed using TETRA-ARMS polymerase chain reaction. Statistical analysis showed no significant association between genotypes and/or alleles with the occurrence of thyroid cancer in the studied population, patients' gender, and tumor type. Nevertheless, we found that the allelic and genotypic distribution of this SNP was associated with the size of thyroid tumors in patients. It is assumed that investigating more individuals from both case and control group may further determine the genotypic and allelic frequencies of this SNP locus in Iranian-Azeri population.

LncRNA CCAT2 promotes malignant progression of metastatic gastric cancer through regulating CD44 alternative splicing.

OBJECTIVE: Gastric cancer (GC) is one of the most malignant tumors worldwide. Thus, it is necessary to explore the underlying mechanisms of GC progression and develop novel therapeutic regimens. Long non-coding RNAs (lncRNAs) have been demonstrated to be abnormally expressed and regulate the malignant behaviors of cancer cells. Our previous research demonstrated that lncRNA colon cancer-associated transcript 2 (CCAT2) has potential value for GC diagnosis and discrimination. However, the functional mechanisms of lncRNA CCAT2 in GC development remain to be explored. METHODS: GC and normal adjacent tissues were collected to detect the expression of lncRNA CCAT2, ESRP1 and CD44 in clinical specimens and their clinical significance for GC patients. Cell counting kit-8, wound healing and transwell assays were conducted to investigate the malignant behaviors in vitro. The generation of nude mouse xenografts by subcutaneous, intraperitoneal and tail vein injection was performed to examine GC growth and metastasis in vivo. Co-immunoprecipitation, RNA-binding protein pull-down assay and fluorescence in situ hybridization were performed to reveal the binding relationships between ESRP1 and CD44. RESULTS: In the present study, lncRNA CCAT2 was overexpressed in GC tissues compared to adjacent normal tissues and correlated with short survival time of patients. lncRNA CCAT2 promoted the proliferation, migration and invasion of GC cells. Its overexpression modulates alternative splicing of Cluster of differentiation 44 (CD44) variants and facilitates the conversion from the standard form to variable CD44 isoform 6 (CD44v6). Mechanistically, lncRNA CCAT2 upregulated CD44v6 expression by binding to epithelial splicing regulatory protein 1 (ESRP1), which subsequently mediates CD44 alternative splicing. The oncogenic role of the lncRNA CCAT2/ESRP1/CD44 axis in the promotion of malignant behaviors was verified by both in vivo and in vitro experiments. CONCLUSIONS: Our findings identified a novel mechanism by which lncRNA CCAT2, as a type of protein-binding RNA, regulates alternative splicing of CD44 and promotes GC progression. This axis may become an effective target for clinical diagnosis and treatment.

Dual Function of CCAT2 in Regulating Luminal Subtype of Breast Cancer Depending on the Subcellular Distribution.

Breast cancer is the most common cancer in women around the world. Emerging evidence has indicated the important roles that non-coding RNAs play in regulating tumor development and progression in breast cancer. Herein, we found a dual function of long non-coding RNA (LncRNA) CCAT2 in the luminal subtype of breast cancer, depending on its subcellular distribution. CCAT2 showed an overall downregulation in the tumor tissues from luminal breast cancer patients. Transient overexpression of CCAT2 in the luminal subtype of breast cancer cell MCF-7 or T47D significantly suppressed cell proliferation in vitro and inhibited tumor growth in vivo. Gene expression analysis of cancer stem cell markers including OCT4, NANOG, h-TERT, SOX2 and KLF4; flow cytometry analysis of breast cancer stem cell population, and mammosphere formation assay demonstrated inhibition of cancer cell stemness with transient transfection of CCAT2 in which exogenous CCAT2 mainly distributed in the cytoplasm and regulated miR-221-p27 signaling via RNA sequence interaction. However, overexpression of CCAT2 in MCF-7 cells through pMX retroviral nuclear expression vector accumulated CCAT2 in the nucleus, leading to upregulation of OCT4-PG1, a pseudogene of stem gene OCT4, thereby promoting the cancer cell stemness. In conclusion, the current study, for the first time, revealed a dual function of lncRNA CCAT2 as a tumor suppressor or oncogene depending upon its subcellular distribution. It also demonstrated the regulatory mechanism of cytoplasmic CCAT2 in suppressing tumorigenesis in the luminal subtype of breast cancer.

CCAT2 knockdown inhibits cell growth, and migration and promotes apoptosis through regulating the hsa-mir-145-5p/AKT3/mTOR axis in tamoxifen-resistant MCF7 cells.

AIMS: Tamoxifen (TAM) selectively modulates estrogen receptors and is widely used in breast cancer treatment. However, resistance to this drug appears in 40 % of estrogen receptor-positive breast cancer patients due to deregulated non-coding RNAs. This study sought to identify a long non-coding-RNA/miRNA/mRNA axis that is involved in the development of resistance to TAM- in MCF7 cells (MCF7-R). MAIN METHODS: Study genes were selected using RNA-seq. The expression of genes was assessed using TCGA cohort analyses and RT-qPCR. To identify potential resistant pathways in MCF7-R, the DAVID and DIANA-miRPath were carried out. The prediction software (RNAhybrid, TargetScan, and LncTar), and RT-qPCR were used to determine the relationship between genes. Next, the MCF7-R was established and RT-qPCR, cell cycle, apoptosis, and wound healing assays were carried out to verify MCF7-R and identify the effects of CCAT2 overexpression and knockdown on the cells. KEY FINDINGS: Based on bioinformatics analyses, CCAT2, AKT3, and mTOR were up-regulated in breast cancer cell lines, tissues, and TAM-resistant cells, while hsa-miR-145-5p was down-regulated. According to DAVID and DIANA-miRPath, PI3K/AKT/mTOR was a pathway involved in MCF7-R. According to the prediction software, and RT-qPCR results, CCAT2/hsa-miR-145-5p and hsa-miR-145-5p/AKT3 had a negative correlation. CCAT2 knockdown could prevent cell growth, and migration, and promote apoptosis in MCF7-R, while CCAT2 overexpression induced the opposite effects. RT-qPCR revealed that the expression of BAX and Bcl-2 genes were regulated in favor of apoptosis, upon CCAT2 knockdown. SIGNIFICANCE: CCAT2 regulates cell cycle, migration, and apoptosis in MCF7-R via the hsa-miR-145-5p/AKT3/mTOR axis. Therefore, CCAT2 may be a target to enhance the sensitivity of resistant MCF7 cells to TAM.

Effect of long noncoding RNA CCAT2 on drug sensitivity to 5-fluorouracil of breast cancer cells through microRNA-145 meditated by p53.

The current study was set out to investigate the mechanism by which silenced long noncoding RNA (lncRNA) colon cancer-associated transcript 2 (CCAT2) modulates the cell growth, migration, invasion, and drug sensitivity of breast cancer (BC) cells to 5-fluorouracil (5-Fu) with the involvement of miR-145 and p53. First, high CCAT2 expression was presented in BC cells and tissues. Subsequently, the links between CCAT2 expression and BC clinicopathological features were analyzed. Highly-expressed CCAT2 was linked to lymph node metastasis, positive progesterone receptor, estrogen receptor, and Ki-67 of BC cells. Then, the gain- and loss-of-function approaches were performed to measure the regulatory role of CCAT2 in the biological processes of BC cells. Silencing of CCAT2 suppressed in vitro cell growth, proliferation, invasion, migration abilities, and epithelial-mesenchymal transformation, increased cell apoptosis, and enhanced drug sensitivity of BC cells. Silencing of CCAT2 upregulated miR-145, which was poorly expressed in drug-resistant BC cells. p53 can bind to the miR-145 promoter region and increase miR-145 expression. Upregulation of miR-145 induced by silencing of CCAT2 can be invalidated by p53-siRNA. To conclude, p53-induced activation of miR-145 could be inhibited by CCAT2, while overexpression of CCAT2 could improve the drug resistance of BC cells to 5-Fu.

Gemini Curcumin Suppresses Gastric Cancer AGS Cell Proliferation Through Modulation of lncRNA CCAT2 and c-Myc Genes.

Objectives: Gemini surfactant nanocurcumin (Gemini-Cur) is a novel formulation of Curcumin (Cur) with dramatic suppressive effects on cancer cells. Here, we investigated the cancer effects of Gemini-Cur in a human gastric adenocarcinoma cell-line (AGS) through the evaluation of the expression of long non-coding RNAs colon cancer-associated transcript-2 (CCAT2) and its downstream c-Myc as known oncogenic modulators of tumorigenesis. Materials and Methods: The AGS cells were treated with Gemini-Cur and pure Cur in a time- and dose-dependent manner. The toxicity of Gemini-Cur was studied using 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and scratch tests. Furthermore, real-time polymerase chain reaction and Western blotting techniques were employed to evaluate the expression of genes. Results: Gemini-Cur significantly affected the viability of AGS cells in a dose- and time-dependent manner with inhibitory concentration 50 values of 59.32, 40.88, and 19.63 µM during 24, 48, and 72 h, respectively. Our findings showed that Gemini-Cur effectively decreased the expression levels of lnc-CCAT2 and c-Myc genes. Western blotting analysis also confirmed the down-regulation of c-Myc in treated samples compared to controls. Conclusion: Gemini-Cur attenuates the proliferation of AGS cells partly through modulation of the lncCCAT2-related pathway.

Long noncoding RNA CCAT2 reduces chemosensitivity to 5-fluorouracil in breast cancer cells by activating the mTOR axis.

Breast cancer (BC) is the most prevalent cancer in women and the second leading cause for cancer-related death in women. LncRNA CCAT2 is involved in BC cell drug sensitivity. Drug resistance of BC cells after chemotherapy is the main obstacle to therapeutic effects. This study explored whether BC cell drug sensitivity to 5-Fu was related to lncRNA CCAT2-regulated mTOR pathway. Normal breast tissues and BC tissues before/after neoadjuvant chemotherapy were collected, and CCAT2 expression was detected by RT-qPCR. Correlation between CCATA2 expression and neoadjuvant chemotherapy efficacy was analysed using the Kendall's tau-b correlation analysis. Normal breast epithelial cells and BC cell lines were cultured. BC cell lines were treated with 5-Fu, and CCAT2 mRNA level in cells was detected. The 5-Fu-resistant MCF-7/5-Fu and MDA-MB-231/5-Fu cells were treated with CCAT2 overexpression/knockdown or CCI-779 (the mTOR pathway inhibitor). The mTOR pathway levels were detected. Expression of apoptosis-related factors was identified. A subcutaneous xenograft model was carried out. High CCAT2 expression was detected in BC tissues and BC drug-resistant cells after neoadjuvant chemotherapy, and a negative link was revealed between CCAT2 expression and efficacy of neoadjuvant chemotherapy. p-mTOR/mTOR in 5-Fu-resistant BC cells with inhibited CCAT2 was decreased, while CCAT2 overexpression activated the mTOR pathway. IC50 value, proliferation, cells in S phase increased and apoptosis reduced after CCAT2 overexpression. After si-CCAT2 or CCI-779 treatment, the growth rate of transplanted tumours was inhibited, while promoted after CCAT2 overexpression. CCAT2 may reduce BC cell chemosensitivity to 5-Fu by activating the mTOR pathway.

Serum CCAT2 as a biomarker for adjuvant diagnosis and prognostic prediction of cervical cancer.

Growing evidence indicates that lncRNA colon cancer-associated transcript 2 (CCAT2) is associated with cancers. However, the clinical value of CCAT2 in cervical cancer (CC) remains unclear. In this study, serum CCAT2 level was detected by real-time quantitative PCR (RT-qPCR). Carbohydrate antigen 125 (CA125) and squamous-cell carcinoma antigen (SCC) were detected by electrochemiluminescence. A receiver operating characteristic (ROC) curve was utilized to estimate the diagnostic efficiency of CCAT2. Kaplan-Meier survival analysis and univariable and multivariable analyses were performed to assess the prognostic value of CCAT2. The relative expression level of CCAT2 in primary CC patients was significantly higher than that in cervical intraepithelial neoplasias (CIN) patients and healthy controls (both P < 0.001). CCAT2 relative expression was positively correlated with tumor Federation of Gynecology and Obstetrics (FIGO) stage, SCC-Ag and lymph node metastasis (LNM) (all P < 0.05). CCAT2 expression in recurrent/metastatic CC was significantly higher compared with primary CC (P < 0.0001) or operated CC (P < 0.0001) and during follow-up, CCAT2 expression was increased before surgery and decreased significantly after surgery (P < 0.0001). Furthermore, the overall survival rate of CC patients with high CCAT2 expression group markedly decreased as compared with that of low CCAT2 expression group (P = 0.026). Univariate analyses indicated that CCAT2 was a poor prognostic factor associated with overall survival (OS). Our study indicates that CCAT2 may be valuable in complementary diagnosis and monitoring of progression and prognosis of CC patients. Combined detection of CCAT2, CA125 and SCC can greatly improve the diagnostic efficiency of primary CC.

Transcriptional Regulation between CCAT2 and AR in Prostate Cancer Cell Lines / 中国生物化学与分子生物学报

AR (androgen receptor) and CCAT2 are two prostate cancer (PCa)-related genes whereas their relationship is not yet reported. AR is the classical major functional gene in PCa progression. CCAT2, a non-coding gene, was identified based on big-data GWAS (Genome-Wide Association Studies) in the year of 2013. Androgen deprivation therapy (ADT) is usually used to treat PCa in the early stage. After persistent androgen deprivation, PCa would generally lead to castration resistant prostate cancer (CRPC), whereas the mechanism is yet unclear. Here we explore the function of AR and CCAT2 in PCa progression, especially their relation in androgen sensitive and insensitive cell model LNCap and DU145. We found a loop between AR and CCAT2 transcription by over-expression and knock-down strategies. In DU145 cells, G-CCAT2 activated AR mRNA level 2. 6 times, while T-CCAT2 inhibited it to 0. 2 times (P<0. 05). In LNCaP cells, G-CCAT2 could activate AR mRNA levels 1. 5 times, and TCCAT2 had no significant effect (P<0. 05). Under overexpression of AR in DU145 cells, the expression of CCAT2 increased 2. 9 times (P < 0. 05). The abundance of CCAT2 decreased to 0. 48 (P < 0. 05) in LNCaP cells by AR knock-down. Reporter gene analysis showed that CCAT2 could function on the AR promoter. We then performed CCK8 assays and AR protein level detection as supplement for the new gene CCAT2 studies. Finally we primarily studied some target genes that are related to AR and CCAT2 . The results showed that the G-CCAT2 transcript could activate AR expression in LNCap cells while UCCAT2 had no significant effect. In DU145 cells, G-CCAT2 exhibited a more relative stronger activation effect on AR, and U-CCAT2 could inhibit AR transcription. AR activates the transcriptional activity of CCAT2 in both cell lines, suggesting a feedback regulation between them. Our data showed that there would be a feedback loop between CCAT2 and AR, which may indicate a new method for PCa treatment.

Long Non-Coding RNA CCAT2 Activates RAB14 and Acts as an Oncogene in Colorectal Cancer.

Here, we investigated the clinicopathological and prognostic potential of the long noncoding RNA Colon Cancer-Associated Transcript 2 (CCAT2) in human colorectal cancer (CRC). We used qPCR to quantify CCAT2 levels in 44 pairs of CRC tissues and adjacent nontumor and healthy colon mucosa tissues, and in several CRC cell lines (SW620, SW480, HT-29, LOVO, HCT116 and DLD-1) and normal human colorectal epithelial cells (HFC). We assessed the effects of CCAT2 overexpression or knockdown on the proliferation, migration and invasion by SW620 and LOVO cells using CCK-8, transwell, and wound-healing assays, respectively. We also investigated the potential interaction between CCAT2 and TAF15 through RNA pull down and rescue experiments. Lastly, we evaluated the expression of the cell cycle progression markers and GSK3ß signaling pathway proteins using Western blotting. Our results showed that CCAT2 was upregulated in CRC tissues and cell lines as com-pared to controls. Ectopic expression of CCAT2 promoted CRC cell proliferation, migration and invasion, likely through direct interaction with TAF15, transcriptional activation of RAB14, and activation of the AKT/GSK3ß signaling pathway. In vivo, CCAT2 promoted CRC cell growth and metastasis in nude mice. Taken together, these results highlight the actions of CCAT2 as a CRC oncogene.

The Roles of the Colon Cancer Associated Transcript 2 (CCAT2) Long Non-Coding RNA in Cancer: A Comprehensive Characterization of the Tumorigenic and Molecular Functions.

Colon cancer-associated transcript 2 (CCAT2) is an intensively studied lncRNA with important regulatory roles in cancer. As such, cumulative studies indicate that CCAT2 displays a high functional versatility due to its direct interaction with multiple RNA binding proteins, transcription factors, and other species of non-coding RNA, especially microRNA. The definitory mechanisms of CCAT2 are its role as a regulator of the TCF7L2 transcription factor, enhancer of MYC expression, and activator of the WNT/ß-catenin pathway, as well as a role in promoting and maintaining chromosome instability through the BOP1-AURKB pathway. Additionally, we highlight how the encompassing rs6983267 SNP has been shown to confer CCAT2 with allele-specific functional and structural particularities, such as the allelic-specific reprogramming of glutamine metabolism. Additionally, we emphasize CCAT2's role as a competitive endogenous RNA (ceRNA) for multiple tumor suppressor miRNAs, such as miR-4496, miR-493, miR-424, miR-216b, miR-23b, miR-34a, miR-145, miR-200b, and miR-143 and the pro-tumorigenic role of the altered regulatory axis. Additionally, due to its upregulation in tumor tissues, wide distribution across cancer types, and presence in serum samples, we outline CCAT2's potential as a biomarker and disease indicator and its implications for the development of resistance against current cancer therapy regiments and metastasis.

Long coding RNA CCAT2 enhances the proliferation and epithelial-mesenchymal transition of cervical carcinoma cells via the microRNA-493-5p/CREB1 axis.

Cervical cancer (CC) is one of the most common malignancies among women. It has been demonstrated that long coding RNAs (lncRNAs) play a crucial role in CC. The purpose of this study was to investigate the role of the colon cancer associated transcript 2 (CCAT2) lncRNA in CC and elucidate its possible mechanisms of action. The expression of CCAT2, the miR-493-5p microRNA (miRNA), and mRNA was detected using qRT-PCR. Cell viability, proliferation, and migration and invasion were determined using the MTT, colony formation, and transwell assays, respectively. The interactions between miR-493-5p and CCAT2 or cAMP response element-binding protein 1 (CREB1) were verified using the luciferase and RNA pull-down assays. The effects of CCAT2 knockdown on in vivo tumor growth were determined using tumor xenografts and immunohistochemistry assays. The expression of CCAT2 was upregulated in CC cells and tissues. However, the knockdown of CCAT2 inhibited the proliferation and epithelial-mesenchymal transition (EMT) of CC cells in vitro and suppressed tumor growth in vivo. Mechanistically, CCAT2 functions as a competing endogenous RNA (ceRNA) to upregulate the expression of CREB1 by binding to miR-493-5p. The overexpression of CREB1 or downregulation of miR-493-5p antagonized the effect of CCAT2 knockdown on the proliferation and EMT of CC cells. The knockdown of CCAT2 suppressed the aggressiveness of CC via the miR-493-5p/CREB1 axis. Therefore, CCAT2 is likely to be a promising therapeutic target for CC.

Long non-coding RNA CCAT2 drives the growth of laryngeal squamous cell carcinoma via regulating YAP activity.

Emerging evidence suggests that long non-coding RNA (lncRNA) is closely associated with numerous human diseases, including cancer. However, the functional relevance of lncRNA in human laryngeal squamous cell carcinoma (LSCC) is largely unknown. In the current study, we described CCAT2, a previously unappreciated oncogenic lncRNA in LSCC. CCAT2 was significantly upregulated in human LSCC tissue and serum samples, associated with larger tumor volume, higher clinical stage, and poorer differentiation status. Lentivirus-mediated CCAT2 knockdown notably repressed the cell viability, colony formation, and DNA synthesis rate of LSCC. Screening of transcription factors revealed that YAP/TEAD activity was affected by CCAT2 in LSCC cells. Further, CCAT2 directly binds to YAP protein and blocks the phosphorylation of YAP induced by LATS1, resulting in the nuclear translocation of YAP and the activation of YAP oncogenic targets, such as CTGF, CYR61 and AMOTL2. Importantly, we also confirmed the regulation of CCAT2 on YAP activity in vivo based on nude mice model. Altogether, we identified a novel lncRNA that controls YAP nucleocytoplasmic shuttling and promotes LSCC cell proliferation. Given the importance of YAP in tumorigenesis and progression, our results provide insights to intervene LSCC by targeting the CCAT2/YAP axis.

CCAT2 enhances autophagy-related invasion and metastasis via regulating miR-4496 and ELAVL1 in hepatocellular carcinoma.

Autophagy is thought to contribute to the pathogenesis of many diseases, including cancer. Long non-coding RNA (lncRNA) CCAT2 functions as an oncogene in a variety of tumours. However, it is still unknown whether CCAT2 is involved in autophagy and metastasis of hepatocellular carcinoma (HCC). In our study, we found that lncRNA CCAT2 expression was significantly increased in HCC tissue and was correlated with advanced stage and venous invasion. Further experiments revealed that CCAT2 induced autophagy and promoted migration and invasion in vitro and in vivo. Mechanistic investigations found that CCAT2 involved in HCC by regulating miR-4496/Atg5 in cytoplasm. In nucleus, CCAT2 bound with ELAVL1/HuR to facilitate HCC progression. Our findings suggest that CCAT2 is an oncogenic factor in the progression of HCC with different regulatory mechanisms and may serve as a target for HCC therapy.

Long Non-Coding RNA CCAT2 Promotes the Development of Esophageal Squamous Cell Carcinoma by Inhibiting miR-200b to Upregulate the IGF2BP2/TK1 Axis.

Long non-coding RNAs (lncRNAs) have been shown to play important roles in human cancers, including esophageal squamous cell carcinoma (ESCC). In the current study, we identified CCAT2 as a relevant lncRNA and investigated its role in the progression of ESCC. RT-qPCR was adopted to detect CCAT2 expression in collected clinical samples, ESCC cell lines, and a normal cell line. We tested the correlation between CCAT2 expression and the prognosis of ESCC. RT-qPCR or immunoblotting was adopted to detect the expression of relevant factors in ESCC tissues or cells. Cell proliferation, apoptosis, migration, and invasion were examined by colony formation assay, flow cytometry, scratch assay, and Transwell assay, respectively, while subcutaneous tumorigenesis in nude mice was adopted to examine the role of CCAT2 in tumorigenesis of ESCC cells in vivo. Bioinformatics analysis, dual luciferase reporter assay, and RIP were conducted for the target relationship profiling. Me-RIP was adopted to detect m6A modification level of TK1 in ESCC tissues or cells. Upregulated CCAT2, IGF2BP2, and TK1 expression and inhibited miR-200b expression were observed in ESCC cells and tissues. CCAT2 bound to miR-200b and reduced its expression, leading to upregulated IGF2BP2 expression. IGF2BP2 improved TK1 mRNA stability to enhance its expression by recognizing its m6A modification. CCAT2 promoted the migration and invasion of ESCC cells in vitro, and tumorigenesis in vivo by upregulating TK1 expression, while overexpression of miR-200b reversed these effects of CCAT2. Overall, this study suggests that CCAT2 competitively binds to miR-200b to alleviate its inhibitory effects on IGF2BP2 expression, resulting in elevated TK1 expression, and an ensuing promotion of the development of ESCC.

The lncRNA CCAT2 Rs6983267 G Variant Contributes to Increased Sepsis Susceptibility in a Southern Chinese Population.

PURPOSE: Accumulating evidence demonstrates that genetic susceptibility genes can be used as biomarkers to assess sepsis susceptibility, and genetic variation is associated with susceptibility and clinical outcomes in patients with sepsis and inflammatory disease. Although studies have shown that the lncRNA CCAT2 is involved in inflammatory diseases, it remains unclear whether CCAT2 gene polymorphisms are associated with susceptibility to inflammatory diseases, such as sepsis, in children. METHODS: We genotyped the rs6983267 CCAT2 polymorphism in 474 cases (pediatric sepsis) and 678 controls using TaqMan methods, and odds ratios (ORs) and 95% confidence intervals (CIs) were used to evaluate the strength of associations. RESULTS: Our results indicate that the rs6983267 T > G polymorphism is significantly associated with an increased risk of sepsis in children (TG and TT: adjusted OR = 1.311, 95% CI = 1.016-1.743, GG and TT: adjusted OR = 1.444, 95% CI = 1.025-2.034 dominant model: GG/TG vs TT adjusted OR = 1.362, 95% CI = 1.055-1.756). Furthermore, the risk effect was more pronounced in children younger than 60 months who were male and who had sepsis. CONCLUSION: We found that the CCAT2 gene polymorphism rs6983267 T > G may be associated with an increased risk of pediatric sepsis in southern China. A larger multicenter study should be performed to confirm these results.

Investigating the association between rs6983267 polymorphism and susceptibility to gastrointestinal cancers in Iranian population.

Genome-wide association studies have revealed that some single nucleotide polymorphisms at 8q24, such as rs6983267, might be effective in susceptibility to various cancers in different populations. Therefore, rs6983267 might be useful as a marker for multiple cancers. In this study, we considered a population, including 478 gastrointestinal cancer cases from the Iranian population, to investigate the association between rs6983267 and susceptibility to gastrointestinal cancers. The samples were genotyped using the TaqMan real-time PCR method while 10% of them were also confirmed by sequencing. Higher frequency of G allele was associated with higher grades of tumors in esophageal cancer and the tumors located in the lower portion of the esophagus (OR 3.56; 95% CI 1.13-11.24; P = 0.03) and cardia (OR 5.24; 95% CI 1.26-21.83; P = 0.02), which both locations are involved in esophageal adenocarcinomas with poor prognosis. The results indicated that in the male subgroup, the rs6983267 GG genotype significantly enhanced the gastric cancer susceptibility (OR 4.76; 95% CI 1.57-14.45; P = 0.01). GG genotype also increased the risk of intestinal-type gastric cancer, located in non-cardia (OR 4.62; 95% CI 1.25-17.04; P = 0.02). Moreover, gastric cancer cases and controls with a family history of gastrointestinal tumors were mostly genotyped with the G allele (OR 3.61; 95% CI = 1.09-12.01; P = 0.04). There were no remarkable associations between rs6983267 and susceptibility to esophageal and colon cancers in the Iranian population. However, different genotypes of rs6983267 had significant correlations with tumor grade, cancer type, and family history of gastrointestinal cancers. Further investigations in a larger population and other ethnicities are required to confirm these results.