Colon Cancer-associated Transcript Research Articles

Long non-coding RNA CCAT2 promotes cholangiocarcinoma cells migration and invasion by induction of epithelial-to-mesenchymal transition

Cholangiocarcinoma (CCA) is one of the most aggressive malignancies in humans. Emerging evidence has indicated that abnormally expressed long non-coding RNAs (lncRNAs) could conduce to tumorigenesis and progression. Specifically, colon cancer-associated transcript 2 (CCAT2) has been reported to be overexpressed in several carcinomas. However, its clinical significance and functional roles in CCA is still unknown. qRT-PCR experiments were conducted to assess the CCAT2 expression in CCA tissue samples and cell lines. In addition, the link between CCAT2 expression and clinicopathological characteristics was analyzed. The potential effects of CCAT2 in CCA cells was evaluated in vitro including cell proliferation, colony-forming ability, apoptosis, migration, invasion and epithelial-to-mesenchymal transition (EMT). As a result, CCAT2 was aberrantly overexpressed in CCA tissue samples and cells, and this upregulation was correlated with tumor size, lymph node invasion, TNM stage and postoperative recurrence in CCA patients. Overexpression of CCAT2 could serve as an independent prognostic indicator for CCA. Additionally, overexpression of CCAT2 was a dismal prognostic indicator for patients with CCA. Furthermore, CCAT2 silencing caused tumor suppressive effects via reducing cell proliferation, migration and invasion, inducing cell apoptosis and reversing the EMT process in HuCCT1 and CCLP1 cells. Collectively, our data illustrated that lncRNA CCAT2 played an oncogenic role in CCA and may offer a potential therapeutic target for treating this fatal disease.

LncRNA colon cancer-associated transcript 1 (CCAT1) promotes proliferation and metastasis of ovarian cancer via miR-1290.

Ovarian cancer is one of the leading causes of cancer-related death in women, but treatment remained unsatisfactory. Studies have shown that lncRNA colon cancer-associated transcript 1 (CCAT1) plays an important regulatory role in different cancers, but its role in ovarian cancer remained largely unclear. Quantitative Real-time polymerase chain reaction (qRT-PCR) was applied to detect the expression of lncRNA CCAT1 in ovarian cancer and adjacent tissue, and analysis was applied to explore the relationship between expression and clinical characteristic. After lncRNA CCAT1 suppression, Cell Counting Kit-8 (CCK8) and wound-healing assay were used to detect the proliferation and metastasis ability of ovarian cancer, respectively. qRT-PCR showed that lncRNA CCAT1 was highly expressed in ovarian cancer tissue, compared with adjacent tissue. Moreover, we found that the expression of lncRNA CCAT1 was closely related to prognosis, tumor size, and lymph node metastasis. We also found that lncRNA CCAT1 could sponge miR-1290 in ovarian cancer. In this study, we found that lncRNA CCAT1 could sponge miR-1290 in ovarian cancer, and was closely related to prognosis, proliferation, and metastasis.

Knockdown of long noncoding RNA CCAT1 inhibits cell growth, invasion and peritoneal metastasis via downregulation of Bmi-1 in gastric cancer

Long noncoding RNA colon cancer-associated transcript 1 (lncRNA CCAT1) is highly expressed in gastric cancer (GC) tissues compared with normal counterparts and CCAT1 upregulation can promote proliferation and migration of GC cells in vitro. B-cell specific moloney leukemia virus insertion site 1 (Bmi-1) expression is positively correlated with tumor progression. The present study aimed to investigate the biological functions of CCAT1 and the relationships between CCAT1 and Bmi-1 in GC progression. In the present study, CCAT1 was knocked down by specific shRNA transfection in two human GC cell lines (MGC-803 and SGC-7901). The effects of CCAT1 knockdown on GC cell proliferation, cell cycle, migration and invasion were investigated in vitro. The effect of CCAT1 knockdown on peritoneal metastasis was assessed in nude mice. Bmi-1 expression levels were examined both in vitro and in vivo. The results showed that CCAT1 knockdown markedly inhibited cell proliferation, migration and invasion, arrested the cell cycle at G0/G1 phase in vitro, and inhibited peritoneal metastasis in nude mice, along with the downregulation of Bmi-1. Taken together, CCAT1 is functionally involved in growth and metastasis of GC cells and it may be a potential target for GC therapy.

LncRNA CCAT1 promotes cell proliferation, migration, and invasion by down-regulation of miR-143 in FTC-133 thyroid carcinoma cell line.

Thyroid cancer is a common malignant tumor. Long non-coding RNA colon cancer-associated transcript 1 (lncRNA CCAT1) is highly expressed in many cancers; however, the molecular mechanism of CCAT1 in thyroid cancer remains unclear. Hence, this study aimed to investigate the effect of CCAT1 on human thyroid cancer cell line FTC-133. FTC-133 cells were transfected with CCAT1 expressing vector, CCAT1 shRNA, miR-143 mimic, and miR-143 inhibitor, respectively. After different treatments, cell viability, proliferation, migration, invasion, and apoptosis were measured. Moreover, the regulatory relationship of CCAT1 and miR-143, as well as miR-143 and VEGF were tested using dual-luciferase reporter assay. The relative expressions of CCAT1, miR-143, and VEGF were tested by qRT-PCR. The expressions of apoptosis-related factors and corresponding proteins in PI3K/AKT and MAPK pathways were analyzed using western blot analysis. The results suggested that CCAT1 was up-regulated in the FTC-133 cells. CCAT1 suppression decreased FTC-133 cell viability, proliferation, migration, invasion, and miR-143 expression, while it increased apoptosis and VEGF expression. CCAT1 might act as a competing endogenous RNA (ceRNA) for miR-143. Moreover, CCAT1 activated PI3K/AKT and MAPK signaling pathways through inhibition of miR-143. This study demonstrated that CCAT1 exhibited pro-proliferative and pro-metastasis functions on FTC-133 cells and activated PI3K/AKT and MAPK signaling pathways via down-regulation of miR-143. These findings will provide a possible target for clinical treatment of thyroid cancer.

Effect of silencing colon cancer-associated transcript 2 on the proliferation, apoptosis and autophagy of gastric cancer BGC-823 cells.

The role of long non-coding RNAs (lncRNAs) in the carcinogenesis and progression of tumors has been receiving increasing attention. Colon cancer-associated transcript 2 (CCAT2), a type of oncogenic lncRNA, is regarded as a novel biomarker of poor prognosis and metastasis in various types of cancer. However, the molecular contributions of CCAT2 to gastric cancer (GC) progression remain largely unclear. The aim of the present study was to demonstrate the effect of silencing CCAT2 on the biological behavior of GC BGC-823 cells and illustrate the potential underlying molecular mechanisms. A short hairpin RNA interference plasmid pRNAT-U6.1-CCAT2 targeting CCAT2 was successfully constructed. At 48 h after transfection with the interference plasmid, the survival rate of BGC-823 cells was significantly decreased, as determined by the MTT assay. In addition, RT-qPCR results revealed that CCAT2 gene expression was effectively suppressed by the transfection, while POU domain class 5 transcription factor 1B (POU5F1B) gene expression was significantly decreased. Terminal deoxynucleotidyl transferase dUTP nick end labeling assay further revealed that the apoptotic index was significantly higher in the interference group. Western blot analysis also demonstrated that the expression of beclin-1 protein was significantly increased, whereas the expression levels of phosphoinositide 3-kinase (PI3K) and mammalian target of rapamycin (mTOR) proteins were downregulated in the interference group. In conclusion, CCAT2 was able to positively regulate the expression of POU5F1B gene. Furthermore, silencing of CCAT2 gene inhibited the proliferation of BGC-823 cells, as well as induced apoptosis and autophagy in BGC-823 cells, by suppression of the PI3K/mTOR signaling pathways.

Long non-coding RNA CCAT2 promotes epithelial-mesenchymal transition involving Wnt/β-catenin pathway in epithelial ovarian carcinoma cells.

Long non-coding RNA colon cancer-associated transcript 2 (CCAT2) is dysregulated in a variety of types of human cancer. However, the role of CCAT2 in epithelial ovarian carcinoma (EOC) remains largely unknown. The aim of this study is to investigate the effect of CCAT2 on epithelial-mesenchymal transition (EMT) and related molecular mechanisms in epithelial ovarian cancer cells. In the current paper, we found that CCAT2 was significantly upregulated in EOC SKOV3, A2780 and HO8910 cell lines compared with the normal ovarian epithelial HUM-CELL-0088 cell line. Functional assays demonstrated that the knockdown of CCAT2 inhibited migration and invasion of EOC cells in vitro. Moreover, our results showed that silencing CCAT2 inhibited EMT by the upregulation of epithelial cadherin and downregulation of neural cadherin, zinc finger protein SNAI and Twist-related protein 1 in SKOV3 and A2780 cell lines. But, that was reversed by the treatment with lithium chloride (LiCl), by which the canonical Wnt/β-catenin pathway could be activated. In addition, we further investigated the role of CCAT2 in the modulation of Wnt/β-catenin signaling pathway. Our results revealed that knockdown of CCAT2 inhibited the expression of β-catenin and the activity of T-cell factor/lymphoid enhancer factor, acting as a key transcription factor of Wnt signaling pathway. Collectively, these results indicate that CCAT2 may promote EMT, at least partly through Wnt/β-catenin signaling pathway in EOC cells. Thus, CCAT2 might play a critical role in EOC progression and serve as a valuable target for the treatment of ovarian cancer.

Knockdown of lncRNA CCAT2 inhibits endometrial cancer cells growth and metastasis via sponging miR-216b.

Colon cancer-associated transcript 2 (CCAT2), a novel lncRNA has been reported as an oncogene in several cancers. This study was aimed to explore whether CCAT2 also exerted oncogenic roles in endometrial cancer cells. The expression of CCAT2 in 30 pairs of endometrial cancer and matched non-cancerous tissues were detected by qRT-PCR. Two endometrial cancer cell lines HEC-1-A and RL95-2 were used throughout this study. CCAT2 in cells was silenced by transfection with shRNA targeted CCAT2, then cell growth and metastasis were assessed by performing trypan blue staining, Transwell assay, and flow cytometry. Dual-luciferase reporter assay was used to detect the combination of miR-216b and CCAT2. Besides, the expression of miR-216b and Bcl-2 in cells were overexpressed or suppressed by transfection with their correspondingly mimic/vector or inhibitor/shRNA. qRT-PCR and western blot analysis were performed to detect the expression of Bcl-2 and main factors in PTEN/PI3K/AKT and mTOR signaling pathways. CCAT2 was highly expressed in endometrial cancer tissues when compared to non-cancerous endometrial tissues. Knockdown of CCAT2 inhibited HEC-1-A and RL95-2 cells viability, migration, invasion, but induced apoptosis. CCAT2 was an endogenous sponge by competing for miR-216b, and miR-216b suppression alleviated CCAT2 silence-diminished cell growth and metastasis. miR-216b negatively regulated Bcl-2 and Bcl-2 could further active PTEN/PI3K/AKT and mTOR signaling pathways. To conclude, these results demonstrated lncRNA CCAT2 was highly expressed in endometrial cancer tissues. Knockdown of CCAT2 inhibited cell growth and metastasis of endometrial cancer cells by sponging miR-216b.

LncRNA CCAT1/miR-130a-3p axis increases cisplatin resistance in non-small-cell lung cancer cell line by targeting SOX4

ABSTRACTBackground: Colon cancer-associated transcript-1 (CCAT1) has been demonstrated to act as an oncogene and promote chemoresistance in several cancers. However, little is known about the underlying mechanism of CCAT1 in cisplatin (DDP) resistance of non-small-cell lung cancer (NSCLC) cells.Methods: qRT-PCR was performed to detect the expression levels of CCAT, miR-130a-3p, or sex-determining region Y-box 4 (SOX4) mRNA. Luciferase reporter assay, RNA immunoprecipitation (RIP), and qRT-PCR analysis were carried out to explore the potential targets of CCAT1 or miR-130a-3p. Effect of CCAT1, miR-130a-3p, or SOX4 on IC50 value of DDP and ATP binding cassette subfamily G member 2 (ABCG2) level in NSCLC cells were determined by cell counting kits-8 (CCK-8) assay and western blot, respectively.Results: CCAT1 and SOX4 were up-regulated, and miR-130a-3p was down-regulated in DDP-resistant NSCLC cells compared with their parental NSCLC cells. CCAT1 directly interacted with miR-130a-3p and negatively regulated miR-130a-3p expression. CCAT1 contributed to DDP resistance of A549/DDP cells by down-regulating miR-130a-3p. miR-130a-3p was found to directly target SOX4 to suppress its expression. SOX4 knockdown reversed miR-130a-3p-inhibition-induced increase of DDP resistance and ABCG2 expression in NSCLC cells. Exogenous expression of SOX4 abrogated CCAT1-knockdown-mediated decrease of DDP resistance and ABCG2 expression in DDP-resistant NSCLC cells.Conclusion: CCAT1/miR-130a-3p axis enhanced DDP resistance of NSCLC cells by targeting SOX4, providing potential targets to overcome DDP resistance and improve efficacy of chemotherapy for patients with NSCLC.

A novel mechanism of lncRNA and miRNA interaction: CCAT2 regulates miR-145 expression by suppressing its maturation process in colon cancer cells

BackgroundAlthough both long and micro RNAs are emerging as important functional components in colorectal cancer (CRC) progression and metastasis, the mechanism of their interaction remains poorly understood. CCAT2 (Colon cancer-associated transcript-2), a long noncoding RNA (lncRNA), has been reported to be over-expressed in CRC and is found to promote tumor growth. miRNAs, a class of naturally occurring short RNAs negatively control the expression of target genes by cleaving mRNA or through translation repression. Recently, we reported that miR-145 and miR-21 cooperate to regulate colon cancer stem cell (CSC) proliferation and differentiation. Considering that CCAT2 is mainly located in the nucleus and miRNA maturation process begins in the nucleus, we hypothesize that CCAT2 selectively blocks miR-145 maturation process, resulting in decreased mature miR-145 affecting colon CSC proliferation and differentiation.MethodsThe levels of CCAT2 were manipulated by transfection of CCAT2 expression plasmid or knockdown by siRNA or by CRISPR/Cas9. Quantitative RT-PCR was performed to examine the expression of CCAT2 and pri-, pre- and mature miR-145/21. Fluorescence in situ hybridization (FISH) was used to visualize CCAT2 in the cells. In vitro processing of pri-miRNA-145 was performed using T7 RNA polymerase and recombinant human Dicer.ResultsWe have observed that modulated expression of CCAT2 regulates the expression of miR-145 in colon cancer HCT-116 and HT-29 cells. Knockout of CCAT2 increases miR-145 and negatively regulates miR-21 in HCT-116 cells, impairs proliferation and differentiation. In contrast, stable up-regulation of CCAT2 decreases mature miR-145 and increases the expression of several CSC markers in colon cancer cells. We have also observed that CCAT2 is enriched in the nucleus and correlates with the expression of pre-miR-145 but not pre-miR-21 in HCT-116 cells. These results indicate CCAT2 selectively blocks miR-145 maturation by inhibiting pre-miR-145 export to cytoplasm. Further, we revealed that CCAT2 blocks cleavage of pre-miR-145 by Dicer in vitro.ConclusionsOur results identify CCAT2 as a negative regulator of miRNA-145 biogenesis, and expose a novel mechanism of lncRNA-miRNA crosstalk.

Overexpression of long non-coding RNA colon cancer-associated transcript 2 is associated with advanced tumor progression and poor prognosis in patients with colorectal cancer.

The aim of the present study was to explore the clinicopathological and prognostic significance of long non-coding RNA (lncRNA) colon cancer-associated transcript 2 (CCAT2) expression in human colorectal cancer (CRC). Expression levels of lncRNA CCAT2 in CRC, adjacent non-tumor and healthy colon mucosa tissues were detected by quantitative polymerase chain reaction. The disease-free survival and overall survival rates were evaluated using the Kaplan-Meier method, and multivariate analysis was performed using Cox proportional hazard analysis. The expression level of lncRNA CCAT2 in CRC tissues was increased significantly compared with adjacent normal tissues or non-cancerous tissues. CCAT2 expression was observed to be progressively increased between tumor-node-metastasis (TNM) stages I and IV. A high level of CCAT2 expression was revealed to be associated with poor cell differentiation, deeper tumor infiltration, lymph node metastasis, distance metastasis, vascular invasion and advanced TNM stage. Compared with patients with low levels of CCAT2 expression, patients with high levels of CCAT2 expression had shorter disease-free survival and overall survival times. Multivariate analyses indicated that high CCAT2 expression was an independent poor prognostic factor. Therefore, increased lncRNA CCAT2 expression maybe a potential diagnostic biomarker for CRC, and an independent predictor of prognosis in patients with CRC.

Long non-coding RNA CCAT1 modulates neuropathic pain progression through sponging miR-155.

Neuropathic pain is caused by dysfunction or primary injury of the somatosensory nervous system. Long noncoding RNAs (lncRNAs) play important roles in the development of neuropathic pain. However, the effects of lncRNA colon cancer associated transcript-1 (CCAT1) in neuropathic pain have not been reported. The model of bilateral sciatic nerve chronic constriction injuries (bCCI) is regarded as long-lasting mechanical hypersensitivity and cold allodynia, which is the representative symptom in the human subjects suffering from the neuropathic pain. In this study, we found that CCAT1 expression was decreased in the spinal dorsal horn, dorsal root ganglion (DRG), hippocampus, and anterior cingulate cortex (ACC) of rats with bCCI. The rats of bCCI presented the cold allodynia after the 14th day of postoperation. We furtherly showed that lncRNA CCAT1 decreased miR-155 expression and enhanced Serum and glucocorticoid regulated protein kinase 3 (SGK3) expression in the NGF-differentiated PC12 cell. We found that miR-155 expression was increased in the spinal dorsal horn, DRG, hippocampus, and ACC of rats with bCCI injuries. However, SGK3 expression was downregulated in the spinal dorsal horn, DRG, hippocampus, and ACC of rats with bCCI injuries. Moreover, lncRNA CCAT1 overexpression could alleviate the pain thresholds and inhibited expression of SGK3 could rescue this effect. In conclusion, these results suggested the crucial roles of CCAT1 and SGK3 in the neuropathic pain.

Expression Study and Clinical Correlations of MYC and CCAT2 in Breast Cancer Patients

Background:Colon cancer-associated transcript 2 (CCAT2) is a newly recognized lncRNA transcribed from the 8q24 genomic region. It functions as an oncogene in various types of cancers including breast cancer, in which it affects Wnt/β-catenin pathway. Previous studies have shown a putative interaction between this lncRNA and MYC proto-oncogene.Methods:In the current study, we evaluated the expression of CCAT2 in breast cancer tissues with regards to the expression of its target MYC. In addition, we assessed the relationship between CCAT2 and MYC expression levels in tumor tissues and the clinical prognostic characteristics of breast cancer patients.Results:MYC expression levels were significantly up-regulated in tumor tissues compared with adjacent non-cancerous tissues (ANCTs), while such analysis showed no statistically significant difference between these two tissue types in CCAT2 expression. Starkly increased CCAT2 gene expression levels were found in 12/48 (25%) of cancer tissue samples compared with their corresponding ANCTs. Furthermore, significant inverse correlations were found between CCAT2 expression and stage, as well as lymph node involvement. Besides, a significant inverse correlation was found between the relative MYC expression in tumor tissues compared with their corresponding ANCTs and disease stage.Conclusions:These results highlight the significance of MYC and CCAT2 expressions in the early stages of breast cancer development and suggest a potentially significant role for CCAT2 in a subset of breast cancer patients, which could be applied as a potential therapeutic target in these patients.

Long noncoding RNA colon cancer associated transcript‑1 promotes the proliferation, migration and invasion of cervical cancer.

Previous studies have revealed significant roles for long noncoding RNA (lncRNA) in the tumorigenesis, metastasis and invasion of various tumors, including cervical cancer. The present study aimed to investigate the potential roles of lncRNA colon cancer associated transcript 1 (CCAT1) in the metastasis and invasion of cervical cancer, and to reveal the potential underlying mechanism. The mRNA expression of lncRNA CCAT1 in cervical cancer tissue was measured using the reverse transcription‑quantitative polymerase chain reaction, and the association between lncRNA CCAT1 and the metastasis of cervical cancer was analyzed. The effects of lncRNA CCAT1 expression on HeLa cell viability, and migration and invasion were also analyzed by MTT and Transwell assays. The results demonstrated that lncRNA CCAT1 was highly expressed in the cervical cancer tissue compared with the adjacent normal tissue. High expression of lncRNA CCAT1 was positively associated with tumor size, and there was correlation between high lncRNA CCAT1 expression and a poor survival rate of cervical cancer. The cell viability, and migratory and invasive abilities were suppressed by silencing CCAT1. The results of the present study indicate that lncRNA CCAT1 was highly expressed in cervical cancer, and may serve important roles in promoting the progression and metastasis of cervical cancer.

Dandelion root extract suppressed gastric cancer cells proliferation and migration through targeting lncRNA-CCAT1

Gastric cancer (GC) is one of the most common tumors worldwide. Standard treatment after early detection involves surgical excision (recurrence is possible), and metastatic gastric cancer is refractory to immuno-, radio-, and most harmful chemotherapies. Various natural compounds have shown efficacy in killing different cancers, albeit not always specifically. In this study, we show that dandelion root extract (DRE) specifically and effectively suppresses proliferation and migration in human gastric cells without inducing toxicity in noncancerous cells. Long noncoding RNAs (lncRNAs) are known to promote tumorigenesis in many cancer types. Here, we showed that the lncRNA colon cancer-associated transcript-1 (CCAT1) was down-regulated in dandelion-treated GC cells. Furthermore, downregulation of CCAT1 inhibited proliferation and migration of gastric cells. We also found that DRE exerted its function in GC cells partially through targeting CCAT1. This data will provide a basis on which further research in cancer treatment through DRE can be executed.

CCAT-1 promotes proliferation and inhibits apoptosis of cervical cancer cells via the Wnt signaling pathway.

Though the long noncoding RNA colon cancer associated transcript-1 (CCAT-1) has been shown to be involved in tumors of other tissues, its involvement in cervical cancer is still unknown. Therefore, the aim of this study was to investigate the molecular mechanism of CCAT-1 in cervical cancer. We quantified the expression of CCAT-1 long noncoding RNA in samples of cervical cancer tissue by real-time PCR. Effects of CCAT-1 expression on the proliferation and apoptosis of HeLa and CaSki cells were assessed by cell-count, colony-formation, and flow cytometry assays. Binding of the c-Myc protein to the CCAT-1 promoter was confirmed by chromatin immunoprecipitation. Finally, TOP-Flash and western blotting were used to examine the regulation of the Wnt/β-catenin pathway by CCAT-1. The results showed that compared with adjacent normal tissue, the expression of CCAT-1 in cervical cancer tissue was significantly upregulated. CCAT-1 expression was related to the stage and size of the tumor and recurrence prognosis. Then, we showed through functional assays that CCAT-1 could promote proliferation and inhibit apoptosis of cervical cancer cells. Furthermore, chromatin immunoprecipitation showed that c-Myc protein could promote CCAT-1 expression by binding to its promoter. Finally, fluorescent-reporter assays and western blotting showed that CCAT-1 could activate the Wnt/β-catenin pathway. In conclusion, we showed that CCAT-1 can be activated by the c-Myc protein and it can promote proliferation and inhibit apoptosis in cervical cancer cells by regulating the Wnt/β-catenin pathway. CCAT-1 might serve as a good prognostic indicator and target for treatment of cervical cancer.

Knockdown of Long Noncoding RNA CCAT2 Inhibits Cellular Proliferation, Invasion, and Epithelial-Mesenchymal Transition in Glioma Cells.

Long noncoding RNA (lncRNA) colon cancer-associated transcript 2 (CCAT2) has been demonstrated to play an important role in diverse tumorigenesis. However, the biological function of lncRNAs in glioma is still unknown. In this study, we found that lncRNA CCAT2 was overexpressed in glioma tissues and cell lines and associated with tumor grade and size. Furthermore, patients with high levels of lncRNA CCAT2 had poorer survival than those with lower levels of lncRNA CCAT2. Knocking down lncRNA CCAT2 expression significantly suppressed the glioma cell growth, migration, and invasion, as well as induced early apoptosis of glioma cells in vitro. Moreover, lncRNA CCAT2 regulated epithelial–mesenchymal transition (EMT)-associated gene expression. In conclusion, lncRNA CCAT2 plays an important role in glioma tumorigenesis and progression and may act as a potential biomarker for therapeutic strategy and prognostic prediction.

Long non-coding RNA CCAT2 promotes cell proliferation and invasion through regulating Wnt/β-catenin signaling pathway in clear cell renal cell carcinoma.

Clear cell renal cell carcinoma (ccRCC) is a common urologic malignancy. Long non-coding RNA colon cancer-associated transcript 2 (CCAT2) has been suggested as serving pivotal roles in tumorigenesis. However, the clinical significance and biological role of CCAT2 in ccRCC remains elusive. The purpose of this study is to identify the function of CCAT2 in ccRCC and its possible molecular mechanism. Expression of CCAT2 was analyzed in 61 ccRCC tissues and two ccRCC cell lines (786-O and ACHN) by quantitative reverse transcription polymerase chain reaction. The functional roles of CCAT2 in ccRCC were determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, colony formation assay, Transwell assay, and flow cytometric analysis. The influence of CCAT2 on tumorigenesis was monitored by in vivo mice xenograft model. The activation of Wnt/β-catenin signaling pathway was evaluated by the TOP/FOP Wnt luciferase reporter assay and western blot assay. CCAT2 expression was markedly higher in ccRCC cell lines and tissues, being positively associated with tumor size and tumor stage in ccRCC patients. Patients with higher CCAT2 expression had a markedly poorer overall survival than did patients with low CCAT2 expression. Knocking down CCAT2 expression led to reduced cell proliferation and increased apoptosis of ccRCC cells in vitro as well as the activation of Wnt/β-catenin signaling pathway, and CCAT2 overexpression remarkably enhanced these oncogenic properties. In vivo mice xenograft model also showed that knocking CCAT2 expression inhibited the growth of ccRCC xenografts. In conclusion, these results indicated that CCAT2 may play a critical role in ccRCC progression and will be further considered as a biomarker for predicting the survival of ccRCC patients and a potential therapeutic target for ccRCC intervention.

Silencing of long non-coding RNA CCAT2 depressed malignancy of oral squamous cell carcinoma via Wnt/β-catenin pathway

Oral squamous cell carcinoma is a common and lethal malignancy affecting the head and neck region. CCAT2 (colon cancer-associated transcript 2) gene is affiliated with long non-coding RNAs, which are often found to have important regulatory roles in cancers. This study aims to assess the expression and clinical significance of CCAT2 gene, identify its malignant biological behaviors, and explore the possible mechanisms in oral squamous cell carcinoma. CCAT2 expression was detected by quantitative real-time polymerase chain reaction, and its relationship with clinical factors was assayed using the Kaplan-Meier survival curve. The biological behaviors of CCAT2 and its potential mechanisms in oral squamous cell carcinoma were explored by the combined use of CCAT2 knockdown technology and the Wnt/β-catenin pathway agonist lithium chloride (LiCl). Our results showed that CCAT2 functioning as a potential oncogene was upregulated in oral squamous cell carcinoma. CCAT2 with high expression level was correlated with poor differentiation, higher T stage, and clinical stage, which made CCAT2 to be a prognostic biomarker in oral squamous cell carcinoma. LiCl-activated Wnt/β-catenin signaling pathway could partly restore the CCAT2-mediated malignant biological behaviors of oral squamous cell carcinoma cells by suppressing β-catenin, CCND1, and MYC and activating glycogen synthase kinase 3 beta expression. These findings might assist in the discovery of novel potential diagnostic and therapeutic target for oral squamous cell carcinoma, thereby improve the effects of clinical treatment in patients.

Prognostic and clinicopathological significance of CCAT2 in Chinese patients with various tumors.

Colon cancer-associated transcript 2 (CCAT2) as a long noncoding RNA (lncRNA) is overexpressed and plays a significant prognostic role in patients with tumors. The present study aimed to comprehensively evaluate the clinical value of CCAT2 in the Chinese population, as a potential prognostic marker in multiple cancers. A systematic search of eligible studies was conducted in the PubMed, Web of Science, Cochrane Library, Wanfang and the China National Knowledge Infrastructure databases as of March 31, 2017. Approximately 1,711 tumor patients from 16 eligible studies were selected. Analyses of the pooled data were performed, and the odds ratio (OR) or hazard ratio (HR) and the 95% confidence interval (95% CI) were calculated and summarized to evaluate the strength of this association using a fixed- or random-effects model. Overall analyses showed that increased CCAT2 expression was associated with a higher risk of lymph node metastasis (LNM), an increased potential for distant metastasis (DM) and higher clinical stage (p<0.001 for LNM, p = 0.001 for DM, p<0.001 for clinical stage). HR and the 95% CI for overall survival (OS) were assessed to pool the effect size using a fixed-effects model. A significant association was observed between increased CCAT2 expression and poor OS (pooled HR = 1.91, 95% CI, 1.63-2.22, p<0.001). These results indicate that CCAT2 is a biomarker to predict tumor progression and a potential prognostic marker in multiple cancers. Additional well-designed clinical studies are needed to validate these findings.

Long non-coding RNA CCAT1/miR-218/ZFX axis modulates the progression of laryngeal squamous cell cancer.

Long non-coding RNAs have been proved to be closely associated with different cancers. This study was designed to elucidate the function and mechanisms of colon cancer-associated transcript-1 in the progression of human laryngeal squamous cell cancer. Expressions of colon cancer-associated transcript-1, microRNA-218, and zinc finger protein, X-linked messenger RNA were measured using quantitative real-time polymerase chain reaction, and the expression level of zinc finger protein, X-linked protein was detected using western blot. Proliferation and invasion of laryngeal squamous cell cancer cell lines were detected by Cell Counting Kit-8 assay and Transwell invasion assay, respectively. Luciferase assay was used to confirm whether microRNA-218 is a target of colon cancer-associated transcript-1 and whether microRNA-218 directly binds to 3'-untranslated region of zinc finger protein, X-linked messenger RNA. Effect of colon cancer-associated transcript-1 on tumor growth was observed through xenograft mice models in vivo. The results showed that expressions of colon cancer-associated transcript-1 and zinc finger protein, X-linked were significantly higher while microRNA-218 expression was significantly lower in the laryngeal squamous cell cancer tissues than those in the adjacent normal tissues. MicroRNA-218 overexpression or zinc finger protein, X-linked silencing significantly suppressed proliferation and invasion of laryngeal squamous cell cancer cells. Moreover, knockdown of colon cancer-associated transcript-1 significantly inhibited proliferation and invasion of laryngeal squamous cell cancer cells, which were reversed by microRNA-218 downregulation or zinc finger protein, X-linked upregulation. Finally, colon cancer-associated transcript-1 silencing inhibited xenograft tumor growth of laryngeal squamous cell cancer in vivo. In conclusion, colon cancer-associated transcript-1 knockdown inhibits proliferation and invasion of laryngeal squamous cell cancer cells through enhancing zinc finger protein, X-linked by sponging microRNA-218, elucidating a novel colon cancer-associated transcript-1-microRNA-218-zinc finger protein, X-linked regulatory axis in laryngeal squamous cell cancer and providing a promising therapeutic target for laryngeal squamous cell cancer patients.