Long Noncoding RNA PVT1 Acts as a "Sponge" to Inhibit microRNA-152 in Gastric Cancer Cells

Prognostic value of long non-coding RNA PVT1 as a novel biomarker in various cancers: a meta-analysis

Background

Plasmacytoma variant translocation 1 (PVT1) has recently been reported to be aberrantly expressed and serves as a prognostic biomarker in many types of cancers. However, its prognostic significance remains controversial. Here, we conducted a meta-analysis to investigate the prognostic value of PVT1 expression in cancers.

Results

A total of 2109 patients from 20 studies were included. The results showed that elevated PVT1 expression predicted a poor outcome for overall survival (OS) in nine types of cancers (HR = 1.40, 95% CI: 1.21–1.59). Subgroup analysis indicated that there was a significant association between PVT1 overexpression and poor OS of patients with gastric cancer, gynecology cancer and lung cancer. Furthermore, we also found a negative significant relationship between PVT1 expression and disease-free survival (HR = 1.83, 95% CI: 1.39–2.27), progression-free survival (HR = 1.63, 95% CI: 1.34–1.93) and recurrence-free survival (HR = 1.74, 95% CI: 1.01–2.47). In addition, the level of PVT1 expression was positively related to tumor size, TNM stage, lymph node metastasis and distant metastases.

Materials and Methods

A systematic search was performed through the PubMed, EMBASE, Web of Science, Ovid and Cochrane library databases for eligible studies on prognostic value of PVT1 in cancers from inception up to June, 2017. The pooled hazard ratios (HRs) or odds ratios (ORs) with 95% confidence intervals (CIs) were used to evaluate the association between PVT1 expression and clinical outcomes.

Conclusions

PVT1 expression positively related to tumor size, TNM stages, lymph node metastasis and distant metastases, and served as a prognostic biomarker in different types of cancers.

Knockdown of LncRNA ANRIL suppresses cell proliferation, metastasis, and invasion via regulating miR-122-5p expression in hepatocellular carcinoma

OBJECTIVE

Previous studies reported that lncRNA antisense non-coding RNA in the INK4 locus (ANRIL) was upregulated in hepatocellular carcinoma (HCC) tissues and decreased expression of ANRIL could suppress cell proliferation, metastasis, and invasion and induce apoptosis of HCC cells. However, the molecular mechanism of ANRIL involved in HCC tumorigenesis is still unknown.

METHODS

The expressions of ANRIL and miR-122-5p in HCC tissues and cells were quantified by qRT-PCR. MTT assay, colony formation assay, wound healing assay, and transwell invasion assay were performed to evaluate cell growth, metastasis, and invasion, respectively. RNA immunoprecipitation (RIP) assay and luciferase reporter assay were performed to determine whether ANRIL could directly bind to miR-122-5p in HCC cells. Xenograft tumor experiment was conducted to confirm the biological role and underlying mechanism of ANRIL in vivo.

RESULTS

The results showed that ANRIL was upregulated and miR-122-5p was downregulated in HCC tissues and cells. ANRIL was negatively correlated with miR-122-5p expression in HCC tissues. Knockdown of ANRIL or miR-122-5p overexpression suppressed HCC cell viability, colony formation ability, metastasis, and invasion. ANRIL was demonstrated to directly bind to miR-122-5p and inhibit its expression. Forced expression of ANRIL abolished the inhibitory effect of miR-122-5p overexpression on HCC progression. In vivo experiment demonstrated that ANRIL knockdown impeded tumor growth in vivo and increased miR-122-5p expression.

CONCLUSION

Our finding suggested that knockdown of ANRIL suppressed cell proliferation, metastasis and invasion via regulating miR-122-5p expression in HCC, illustrating the underlying mechanism of the oncogenic role of ANRIL in HCC.

Reciprocal regulation of DGCR5 and miR-320a affects the cellular malignant phenotype and 5-FU response in pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is one of the most aggressive and lethal malignancies. Long non-coding microRNAs (lncRNAs) are a newly discovered type of regulatory molecule with both diagnostic and prognostic value, but the role of lncRNA in PDAC has not been well investigated until now. Here, we present evidence that shows that the lncRNA DGCR5 is significantly reduced in PDAC tissues as well as in PDAC cell lines and that the downregulation of DGCR5 predicts poor prognosis. Ectopic expression of DGCR5 inhibits the proliferation and migration, and promotes 5-FU resistances of PDAC cells. Further experiments demonstrated that DGCR5 and miR-320a regulate each other in a reciprocal manner and that DGCR5 reverses the inhibition of PDCD4 by miR-320a, which is involved in the regulation of the PDAC cell phenotype and response to 5-FU. Our findings provide novel information about the functions of lncRNAs in PDAC, some of which might be beneficial to the precise diagnosis, prognosis and individualized therapy of patients with PDAC in the future.

Long non-coding RNA PVT1: Emerging biomarker in digestive system cancer

The digestive system cancers are leading cause of cancer-related death worldwide, and have high risks of morbidity and mortality. More and more long non-coding RNAs (lncRNAs) have been studied to be abnormally expressed in cancers and play a key role in the process of digestive system tumour progression. Plasmacytoma variant translocation 1 (PVT1) seems fairly novel. Since 1984, PVT1 was identified to be an activator of MYC in mice. Its role in human tumour initiation and progression has long been a subject of interest. The expression of PVT1 is elevated in digestive system cancers and correlates with poor prognosis. In this review, we illustrate the various functions of PVT1 during the different stages in the complex process of digestive system tumours (including oesophageal cancer, gastric cancer, colorectal cancer, hepatocellular carcinoma and pancreatic cancer). The growing evidence shows the involvement of PVT1 in both proliferation and differentiation process in addition to its involvement in epithelial to mesenchymal transition (EMT). These findings lead us to conclude that PVT1 promotes proliferation, survival, invasion, metastasis and drug resistance in digestive system cancer cells. We will also discuss PVT1's potential in diagnosis and treatment target of digestive system cancer. There was a great probability PVT1 could be a novel biomarker in screening tumours, prognosis biomarkers and future targeted therapy to improve the survival rate in cancer patients.

Molecular Crosstalking among Noncoding RNAs: A New Network Layer of Genome Regulation in Cancer

Over the past few years, noncoding RNAs (ncRNAs) have been extensively studied because of the significant biological roles that they play in regulation of cellular mechanisms. ncRNAs are associated to higher eukaryotes complexity; accordingly, their dysfunction results in pathological phenotypes, including cancer. To date, most research efforts have been mainly focused on how ncRNAs could modulate the expression of protein-coding genes in pathological phenotypes. However, recent evidence has shown the existence of an unexpected interplay among ncRNAs that strongly influences cancer development and progression. ncRNAs can interact with and regulate each other through various molecular mechanisms generating a complex network including different species of RNAs (e.g., mRNAs, miRNAs, lncRNAs, and circRNAs). Such a hidden network of RNA-RNA competitive interactions pervades and modulates the physiological functioning of canonical protein-coding pathways involved in proliferation, differentiation, and metastasis in cancer. Moreover, the pivotal role of ncRNAs as keystones of network structural integrity makes them very attractive and promising targets for innovative RNA-based therapeutics. In this review we will discuss: (1) the current knowledge on complex crosstalk among ncRNAs, with a special focus on cancer; and (2) the main issues and criticisms concerning ncRNAs targeting in therapeutics.

Long Noncoding RNA HOXA11-AS Functions as miRNA Sponge to Promote the Glioma Tumorigenesis Through Targeting miR-140-5p

Long noncoding RNAs (lncRNAs) have been proved as important regulators in many diseases, including cancers. HOXA11 antisense RNA (HOXA11-AS) is a novel identified lncRNA associated with cancer progression. However, the role of HOXA11-AS in glioma remains poorly understood and needs to be elucidated. The purpose of this study is to investigate the role and regulating mechanism of HOXA11-AS on gliomagenesis. Expression of HOXA11-AS was significantly upregulated in glioma tissue and cell lines compared with the adjacent normal tissue and cells. Moreover, patients with high HOXA11-AS expression had a shorter survival and poorer prognosis than that of lower expression. Loss-of-function experiments revealed that HOXA11-AS knockdown inhibited the proliferation, induced cell cycle arrest at G0/G1 phase, and enhanced the apoptosis. Bioinformatics prediction forecast that miR-140-5p directly targeted HOXA11-AS at 3'-UTR, which was confirmed by luciferase reporter assay. In vitro rescue experiment assays, miR-140-5p inhibitor transfection, could reverse the function of HOXA11-AS knockdown on the proliferation, cell cycle arrest, and apoptosis. Taken together, the present study illustrates that the pathway of HOXA11-AS sponging miR-140-5p might play a vital regulating role in the development and progression of glioma.

LINC00052 upregulates EPB41L3 to inhibit migration and invasion of hepatocellular carcinoma by binding miR-452-5p

Numerous studies have demonstrated that a class of long noncoding RNAs (lncRNAs) are dysregulated in hepatocellular carcinoma (HCC) and they are closely related with tumorigenesis. Our previous studies indicated that LINC00052 was a downregulated lncRNA in HCC and acted as a tumor suppressor gene. Using transcription microarray analysis, we found that knockdown of LINC00052 resulted in EPB41L3 downregulation. However, the function of EPB41L3 and the mechanism of LINC00052 downregulating EPB41L3 in HCC remain unclear. In this study, we found that overexpression of LINC00052 could upregulate the EPB41L3 expression and it might serve as a tumor suppressor gene in HCC. Database analysis showed that miR-452-5P could target LINC00052. The binding regions between LINC00052 and miR-452-5P were confirmed by luciferase assays. Moreover, LINC00052 inhibited cell malignant behavior by increasing miR-452-5P expression, suggesting that LINC00052 was negatively regulated by miR-452-5P. In addition, overexpression of miR-452-5P resulted in a decrease of EPB41L3 expression, suggesting that EPB41L3 was as a target of miR-452-5P. In conclusion, these results demonstrated that a novel pathway was mediated by LINC00052 in HCC.