Upregulation of SOX2 activated LncRNA PVT1 expression promotes breast cancer cell growth and invasion

Long noncoding RNA PVT1-214 promotes proliferation and invasion of colorectal cancer by stabilizing Lin28 and interacting with miR-128

Long noncoding RNAs (lncRNAs) are implicated in human cancer, but their mechanisms of action are largely unknown. In this study, we investigated lncRNA alterations that contribute to colorectal cancer (CRC) through microarray expression profiling in CRC patient samples. Here, we report that the CRC-associated lncRNA PVT1-214 is a key regulator of CRC development and progression; patients with high PVT1-214 expression had a shorter survival and poorer prognosis. In vitro and in vivo investigation of the role of PVT1-214 revealed a complex integrated phenotype affecting cell growth, stem-like properties, migration, and invasion. Furthermore, using RNA pull-down and mass spectrometry, we found that Lin28 (also known as Lin28A), a highly conserved RNA-binding protein, is associated with PVT1-214. Strikingly, we found that PVT1-214 not only upregulated Lin28 protein expression in CRC cells by stabilizing Lin28, but also participated in crosstalk with Lin28 mRNA through competition for miR-128 binding, imposing an additional level of post-transcriptional regulation. In addition, we further show that PVT1-214 repressed expression of let-7 family miRNAs, which was abrogated by Lin28 knockdown. Taken together, our findings support a model in which the PVT1-214/Lin28/let-7 axis serves as a critical regulator of CRC pathogenesis, which may simulate a new direction for CRC therapeutic development.

In Silico and In Vitro Analyses of LncRNAs as Potential Regulators in the Transition from the Epithelioid to Sarcomatoid Histotype of Malignant Pleural Mesothelioma (MPM)

Malignant pleural mesothelioma (MPM) is a rare malignancy, with extremely poor survival rates. At present, treatment options are limited, with no second line chemotherapy for those who fail first line therapy. Extensive efforts are ongoing in a bid to characterise the underlying molecular mechanisms of mesothelioma. Recent research has determined that between 70–90% of our genome is transcribed. As only 2% of our genome is protein coding, the roles of the remaining proportion of non-coding RNA in biological processes has many applications, including roles in carcinogenesis and epithelial–mesenchymal transition (EMT), a process thought to play important roles in MPM pathogenesis. Non-coding RNAs can be separated loosely into two subtypes, short non-coding RNAs (<200 nucleotides) or long (>200 nucleotides). A significant body of evidence has emerged for the roles of short non-coding RNAs in MPM. Less is known about the roles of long non-coding RNAs (lncRNAs) in this disease setting. LncRNAs have been shown to play diverse roles in EMT, and it has been suggested that EMT may play a role in the aggressiveness of MPM histological subsets. In this report, using both in vitro analyses on mesothelioma patient material and in silico analyses of existing RNA datasets, we posit that various lncRNAs may play important roles in EMT within MPM, and we review the current literature regarding these lncRNAs with respect to both EMT and MPM.

Knockdown of long non‑coding RNA PVT1 reverses multidrug resistance in colorectal cancer cells

Multidrug resistance (MDR) is one of the primary causes of chemotherapy failure in colorectal cancer (CRC), and extensive biological studies into MDR are required. The non-coding RNA plasmacytoma variant translocation 1 (PVT1) has been demonstrated to be associated with low survival rates in patients with CRC. However, whether PVT1 serves a critical function in the MDR of CRC remains to be determined. To determine the association between PVT1 expression and 5-fluorouracil (5-FU) resistance in CRC, the expression levels of PVT1 mRNA in 5-FU-resistant CRC tissues and cell lines (HCT-8/5-FU and HCT-116/5-FU) were assessed by a reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Cytotoxicity was evaluated using a Cell Counting Kit-8 assay and apoptosis rates were assessed via flow cytometry. In the present study, PVT1 mRNA was highly expressed in 5-FU-resistant CRC tissues and cell lines. HCT-8/5-FU and HCT-116/5-FU cells transfected with small interfering RNA PVT1 and treated with 5-FU exhibited higher apoptotic rates and lower survival rates. By contrast, overexpression of PVT1 in HCT-8 and HCT-116 cells transfected with lentiviral vector-PVT1-green fluorescent protein and treated with 5-FU exhibited lower apoptosis rates and higher survival rates. RT-qPCR and western blotting demonstrated that the overexpression of PVT1 increased the mRNA and protein expression levels of multidrug resistance-associated protein 1, P-glycoprotein, serine/threonine-protein kinase mTOR and apoptosis regulator Bcl2. The present study indicates that PVT1 overexpression may promote MDR in CRC cells, and suggested that inhibition of PVT1 expression may be an effective therapeutic strategy for reversing MDR in CRC.

The emerging co-regulatory role of long noncoding RNAs in epithelial-mesenchymal transition and the Warburg effect in aggressive tumors

Malignant tumor cells have several unique characteristics, and their ability to undergo epithelial-mesenchymal transition (EMT) is a molecular gateway to invasive behavior. Rapid proliferation and increased invasiveness during EMT enhance aberrant glucose metabolism in tumor cells. Meanwhile, aerobic glycolysis provides energy, biosynthesis precursors, and an appropriate microenvironment to facilitate EMT. Reciprocal crosstalk between the processes synergistically contributes to malignant cancer behaviors, but the regulatory mechanisms underlying this interaction remain unclear. Long non-coding RNAs (lncRNAs) are a recently recognized class of RNAs involved in multiple physiological and pathological tumor activities. Increasing evidence indicates that lncRNAs play overlapping roles in both EMT and cancer metabolism. In this review, we describe the lncRNAs reportedly involved in the two biological processes and explore the detailed mechanisms that could help elucidate this co-regulatory network and provide a theoretical basis for clinical management of EMT-related malignant phenotypes.

Upregulation of SOX2-activated lncRNA ANRIL promotes nasopharyngeal carcinoma cell growth

Recent molecularly targeted approaches have gained advances in nasopharyngeal carcinoma treatment. However, the estimated five-year survival rate has not met the desired degree of improvement. Here, we report that upregulation of the expression of the SOX2-activated lncRNA ANRIL is involved in nasopharyngeal carcinoma. ANRIL has been found to be upregulated in clinical nasopharyngeal carcinoma. Using genetic approaches targeting ANRIL in nasopharyngeal carcinoma cells, we found that the knockdown of ANRIL inhibits cell proliferation in vitro and in vivo. Mechanistically, SOX2 binds with ANRIL and increases its RNA level, which upregulates β-catenin signalling, resulting in enhanced nasopharyngeal carcinoma tumourigenesis. Expression levels of ANRIL are positively correlated with SOX2 and β-catenin in clinical nasopharyngeal carcinoma samples. Our findings demonstrate that the SOX2-ANRIL-β-catenin axis plays a critical role in nasopharyngeal carcinoma proliferation and provide a potential therapeutic approach for nasopharyngeal carcinoma patients.

Long non-coding RNA PVT1 facilitates cell proliferation by epigenetically regulating FOXF1 in breast cancer

Plasmacytoma variant translocation 1 (PVT1) expression was elevated in breast cancer tissues and correlated to breast cancer progression and prognosis.

High expression of lncRNA PVT1 independently predicts poor overall survival in patients with primary uveal melanoma

The plasmacytoma variant translocation 1 gene (PVT1) plays an oncogenic role in the initiation and progression of multiple cancers. In this study, by using deep-sequencing data and follow-up data in the Cancer Genome Atlas-Uveal melanomas (TCGA-UVM), we assessed the association between the expression of PVT1 and clinicopathological characteristics of patients with uveal melanoma, the mechanism of its dysregulation and its prognostic value. Results showed that high PVT1 expression group had a higher proportion of epithelioid cell dominant disease (a more malignant histological subtype than spindle cell dominant disease) and more cases of extrascleral extension (a risk factor for metastasis) compared with the low PVT1 expression group. 61 out of 80 cases (76.3%) of primary uveal melanoma had PVT1 amplification in TCGA-UVM. In addition, PVT1 expression was strongly and negatively correlated with its methylation status (Pearson's r = -0.712, Spearman's r = -0.806). By performing univariate and multivariate analysis, we found that high PVT1 expression was an independent predictor of poor OS in patients with uveal melanoma (HR: 12.015, 95%CI: 1.854-77.876, p = 0.009). Based on these findings, we infer that PVT1 expression is modulated by both DNA amplification and methylation and its expression might serve as a valuable and specific prognostic biomarker in terms of OS in uveal melanoma.

Long noncoding RNA SNHG15 promotes human breast cancer proliferation, migration and invasion by sponging miR-211-3p

Long non-coding RNAs (lncRNA) have been demonstrated to act as essential regulators in the development and progression of breast cancer. In our study, we found that long noncoding RNA SNHG15 was highly expressed in breast cancer tissues and cell lines. And the expression of SNHG15 was correlated with TNM stage, lymphnode metastasis and survival in breast cancer patients. SNHG15 knockdown significantly inhibited the proliferation and induced apoptosis in breast cancer cells in vitro and in vivo. Besides, SNHG15 downregulation suppressed cell migration and invasion in MCF-7 and BT-20 cells, and inhibited epithelial-mesenchymal transition (EMT). In mechanism, we found that SNHG15 acted as a competing endogenous RNA to sponge miR-211-3p, which was downregulated in breast cancers and inhibited cell proliferation and migration. Our results showed that there was a negative correlation between SNHG15 and miR-211-3p expression in breast cancer patients. Collectively, we, for the first time, revealed the functions of SNHG15 and miR-211-3p in breast cancer.