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

The multifaceted role of SOX2 in breast and lung cancer dynamics

Breast and lung cancers are leading causes of death among patients, with their global mortality and morbidity rates increasing. Conventional treatments often prove inadequate due to resistance development. The alteration of molecular interactions may accelerate cancer progression and treatment resistance. SOX2, known for its abnormal expression in various human cancers, can either accelerate or impede cancer progression. This review focuses on examining the role of SOX2 in breast and lung cancer development. An imbalance in SOX2 expression can promote the growth and dissemination of these cancers. SOX2 can also block programmed cell death, affecting autophagy and other cell death mechanisms. It plays a significant role in cancer metastasis, mainly by regulating the epithelial-to-mesenchymal transition (EMT). Additionally, an imbalanced SOX2 expression can cause resistance to chemotherapy and radiation therapy in these cancers. Genetic and epigenetic factors may affect SOX2 levels. Pharmacologically targeting SOX2 could improve the effectiveness of breast and lung cancer treatments.

Constructing lncRNA-miRNA-mRNA networks specific to individual cancer patients and finding prognostic biomarkers

BACKGROUND

The competitive endogenous RNA (ceRNA) hypothesis suggests that microRNAs (miRNAs) mediate a regulatory relation between long noncoding RNAs (lncRNAs) and messenger RNAs (mRNAs) which share similar miRNA response elements (MREs) to bind to the same miRNA. Since the ceRNA hypothesis was proposed, several studies have been conducted to construct a network of lncRNAs, miRNAs and mRNAs in cancer. However, most cancer-related ceRNA networks are intended for representing a general relation of RNAs in cancer rather than for a patient-specific relation. Due to the heterogeneous nature of cancer, lncRNA-miRNA-mRNA interactions can vary in different patients.

RESULTS

We have developed a new method for constructing a ceRNA network of lncRNAs, miRNAs and mRNAs, which is specific to an individual cancer patient and for finding prognostic biomarkers consisting of lncRNA-miRNA-mRNA triplets. We tested our method on extensive data sets of three types of cancer (breast cancer, liver cancer, and lung cancer) and obtained potential prognostic lncRNA-miRNA-mRNA triplets for each type of cancer.

CONCLUSIONS

Analysis of expression patterns of the RNAs involved in the triplets and survival rates of cancer patients revealed several interesting findings. First, even for the same cancer type, prognostic lncRNA-miRNA-mRNA triplets can be different depending on whether lncRNA and mRNA show opposite or similar expression patterns. Second, prognostic lncRNA-miRNA-mRNA triplets are often more predictive of survival rates than RNA pairs or individual RNAs. Our approach will be useful for constructing patient-specific lncRNA-miRNA-mRNA networks and for finding prognostic biomarkers from the networks.

The tale of SOX2: Focusing on lncRNA regulation in cancer progression and therapy

Long non-coding RNAs (lncRNAs) have emerged as influential contributors to diverse cellular processes, which regulate gene function and expression via multiple mechanistic pathways. Therefore, it is essential to exploit the structures and interactions of lncRNAs to comprehend their mechanistic functions within cells. A growing body of evidence has revealed that deregulated lncRNAs are involved in multiple regulations of malignant events including cell proliferation, growth, invasion, and metabolism. SRY-related high mobility group box (SOX)2, a well-recognized member of the SOX family, is commonly overexpressed in various types of cancer, contributing to tumor progression and maintenance of stemness. Emerging studies have shown that lncRNAs interact with SOX2 to remarkably contribute to carcinogenesis and disease states. This review elaborates on the crosstalk between the intricate and complicated functions of lncRNAs and SOX2 in the context of malignant diseases. We elucidate distinct molecular mechanisms that contribute to the onset/advancement of cancer, indicating that lncRNAs/SOX2 axes hold immense promise for potential therapeutic targets. Furthermore, we delve into the modalities of emerging feasible treatment options for targeting lncRNAs, highlighting the limitations of such therapies and providing novel insights into further ameliorations of targeted strategies of lncRNAs to promote the clinical implications. Translating current discoveries into clinical applications could ultimately boost improved survival and prognosis of cancer patients.

Deregulated transcription factors in the emerging cancer hallmarks

Cancer progression is a multifaceted process that entails several stages and demands the persistent expression or activation of transcription factors (TFs) to facilitate growth and survival. TFs are a cluster of proteins with DNA-binding domains that attach to promoter or enhancer DNA strands to start the transcription of genes by collaborating with RNA polymerase and other supporting proteins. They are generally acknowledged as the major regulatory molecules that coordinate biological homeostasis and the appropriate functioning of cellular components, subsequently contributing to human physiology. TFs proteins are crucial for controlling transcription during the embryonic stage and development, and the stability of different cell types depends on how they function in different cell types. The development and progression of cancer cells and tumors might be triggered by any anomaly in transcription factor function. It has long been acknowledged that cancer development is accompanied by the dysregulated activity of TF alterations which might result in faulty gene expression. Recent studies have suggested that dysregulated transcription factors play a major role in developing various human malignancies by altering and rewiring metabolic processes, modifying the immune response, and triggering oncogenic signaling cascades. This review emphasizes the interplay between TFs involved in metabolic and epigenetic reprogramming, evading immune attacks, cellular senescence, and the maintenance of cancer stemness in cancerous cells. The insights presented herein will facilitate the development of innovative therapeutic modalities to tackle the dysregulated transcription factors underlying cancer.

KTN1-AS1, a SOX2-mediated lncRNA, activates epithelial-mesenchymal transition process in esophageal squamous cell carcinoma

Kinectin 1 antisense RNA 1 (KTN1-AS1), a long non-coding RNA (lncRNA), has been proved to have tumor-promoting properties and its expression is enhanced in several human tumors. However, the role of KTN1-AS1 in the pathogenesis of esophageal squamous cell carcinoma (ESCC) remains unknown. This study aimed to investigate the expression status, functional roles, and molecular mechanisms of KTN1-AS1 in the development of ESCC. Considerable upregulation of KTN1-AS1 was confirmed in esophageal cancer cells and ESCC tissues and its expression was associated with TNM stage, pathological differentiation, and lymph node metastasis. SOX2 directly activated transcription of KTN1-AS1, and overexpression of KTN1-AS1 facilitated ESCC cells proliferation and invasion in vitro and in vivo. Furthermore, KTN1-AS1 could bind to retinoblastoma binding protein 4 (RBBP4) in the nucleus and enhanced its binding with histone deacetylase 1 (HDAC1), thereby activating the epithelial-mesenchymal transition (EMT) process through downregulating E-cadherin expression at the epigenetic level. In conclusion, KTN1-AS1, induced by SOX2, acts as a tumor-promoting gene and may serve as a potential therapeutic and prognostic biomarker for ESCC.

lncRNA PVT1: a novel oncogene in multiple cancers

Long noncoding RNAs are involved in epigenetic gene modification, including binding to the chromatin rearrangement complex in pre-transcriptional regulation and to gene promoters in gene expression regulation, as well as acting as microRNA sponges to control messenger RNA levels in post-transcriptional regulation. An increasing number of studies have found that long noncoding RNA plasmacytoma variant translocation 1 (PVT1) plays an important role in cancer development. In this review of a large number of studies on PVT1, we found that PVT1 is closely related to tumor onset, proliferation, invasion, epithelial–mesenchymal transformation, and apoptosis, as well as poor prognosis and radiotherapy and chemotherapy resistance in some cancers. This review comprehensively describes PVT1 expression in various cancers and presents novel approaches to the diagnosis and treatment of cancer.

Hypoxia-induced PVT1 promotes lung cancer chemoresistance to cisplatin by autophagy via PVT1/miR-140-3p/ATG5 axis

Lung cancer is one of the most common and lethal malignant tumors and the cases increased rapidly. Elevated chemoresistance during chemotherapy resistance remains a challenge. Hypoxia is one of the components that lead to chemoresistance. PVT1 participates in various tumor drug resistance and is associated with hypoxia conditions. The present study aimed to analyze the regulatory relationship of hypoxia and PVT1 and the mechanism of PVT1 in the hypoxia-induced chemoresistance process of lung cancer. The expression of PVT1 in lung cancer and adjacent tissues, and cell lines were analyzed using the TCGA database and qPCR. The regulatory relationship between hypoxia and PVT1 was validated and analyzed with qPCR, luciferase reporter system, and CHIP-qPCR. The role of PVT1 in chemoresistance ability induced by hypoxia was analyzed with CCK-8 assay and flow cytometry. The roles of PVT1, hypoxia, and chemoresistance were also analyzed with LC3-GFP transfection, WB, and IHC. Finally, the results were further validated in xenograft models. PVT1 is highly expressed in lung cancer and cell lines, and the expression of PVT1 is regulated by HIF-1α, and the luciferase reporter assay and CHIP-qPCR analysis indicated that HIF-1α could bind to the promoter region of PVT1 and regulate PVT1 expression. PVT1 participated in hypoxia-induced chemoresistance and induced higher viability and lower apoptosis rate by the autophagy signaling pathway via PVT1/miR-140-3p/ATG5 axis. All the findings were validated in the xenograft models. In conclusion, these results suggest that the expression of PVT1 is regulated by HIF-1α and participates in hypoxia-induced chemoresistance.

LncRNAs, the Molecules Involved in Communications With Colorectal Cancer Stem Cells

Colorectal cancer stem cells (CRCSCs) can actively self-renew, as well as having multidirectional differentiation and tumor regeneration abilities. Because the high functional activities of CRCSCs are associated with low cure rates in patients with colorectal cancer, efforts have sought to determine the function and regulatory mechanisms of CRCSCs. To date, however, the potential regulatory mechanisms of CRCSCs remain incompletely understood. Many non-coding genes are involved in tumor invasion and spread through their regulation of CRCSCs, with long non-coding RNAs (lncRNAs) being important non-coding RNAs. LncRNAs may be involved in the colorectal cancer development and drug resistance through their regulation of CRCSCs. This review systematically evaluates the latest research on the ability of lncRNAs to regulate CRCSC signaling pathways and the involvement of these lncRNAs in colorectal cancer promotion and suppression. The regulatory network of lncRNAs in the CRCSC signaling pathway has been determined. Further analysis of the potential clinical applications of lncRNAs as novel clinical diagnostic and prognostic biomarkers and therapeutic targets for colorectal cancer may provide new ideas and protocols for the prevention and treatment of colorectal cancer.

Molecular and cellular functions of long non-coding RNAs in prostate and breast cancer

Long noncoding RNAs (lncRNAs) are defined as noncoding RNA transcripts with a length greater than 200 nucleotides. Research over the last decade has made great strides in our understanding of lncRNAs, especially in the biology of their role in cancer. In this article, we will briefly discuss the biogenesis and characteristics of lncRNAs, then review their molecular and cellular functions in cancer by using prostate and breast cancer as examples. LncRNAs are abundant, diverse, and evolutionarily, less conserved than protein-coding genes. They are often expressed in a tumor and cell-specific manner. As a key epigenetic factor, lncRNAs can use a wide variety of molecular mechanisms to regulate gene expression at each step of the genetic information flow pathway. LncRNAs display widespread effects on cell behavior, tumor growth, and metastasis. They act intracellularly and extracellularly in an autocrine, paracrine and endocrine fashion. Increased understanding of lncRNA's role in cancer has facilitated the development of novel biomarkers for cancer diagnosis, led to greater understanding of cancer prognosis, enabled better prediction of therapeutic responses, and promoted identification of potential targets for cancer therapy.

Understanding the function and regulation of Sox2 for its therapeutic potential in breast cancer

Sox family of transcriptional factors play essential functions in development and are implicated in multiple clinical disorders, including cancer. Sox2 being their most prominent member and performing a critical role in reprogramming differentiated adult cells to an embryonic phenotype is frequently upregulated in multiple cancers. High Sox2 levels are detected in breast tumor tissues and correlate with a worse prognosis. In addition, Sox2 expression is connected with resistance to conventional anticancer therapy. Together, it can be said that inhibiting Sox2 expression can reduce the malignant features associated with breast cancer, including invasion, migration, proliferation, stemness, and chemoresistance. This review highlights the critical roles played by the Sox gene family members in initiating or suppressing breast tumor development, while primarily focusing on Sox2 and its role in breast tumor initiation, maintenance, and progression, elucidates the probable mechanisms that control its activity, and puts forward potential therapeutic strategies to inhibit its expression.

Proteomic analysis of inhibitor of apoptosis protein‑like protein‑2 on breast cancer cell proliferation

Although inhibitor of apoptosis protein-like protein-2 (ILP-2) is considered to be a novel enhancer of breast cancer proliferation, its underlying mechanism of action remains unknown. Therefore, the present study aimed to investigate the expression profile of ILP-2-related proteins in MCF-7 cells to reveal their effect on promoting breast cancer cell proliferation. The isobaric tags for relative and absolute quantification (iTRAQ) method was used to analyse the expression profile of ILP-2-related proteins in MCF-7 breast cancer cells transfected with small interfering (si)RNA against ILP-2 (siRNA-5 group) and the negative control (NC) siRNA. The analysis of the iTRAQ data was carried out using western blotting and reverse transcription-quantitative PCR. A total of 4,065 proteins were identified in MCF-7 cells, including 241 differentially expressed proteins (DEPs; fold change ≥1.20 or ≤0.83; P<0.05). Among them, 156 proteins were upregulated and 85 were downregulated in the siRNA-5 group compared with in the NC group. The aforementioned DEPs were mainly enriched in ‘ECM-receptor interaction’. In addition, the top 10 biological processes related to these proteins were associated with signal transduction, cell proliferation and immune system processes. Furthermore, ILP-2 silencing upregulated N(4)-(β-N-acetylglucosaminyl)-L-asparaginase, metallothionein-1E and tryptophan 2,3-dioxygenase, whereas ILP-2 overexpression exerted the opposite effect. The results of the present study suggested that ILP-2 could promote breast cancer growth via regulating cell proliferation, signal transduction, immune system processes and other cellular physiological activities.

PVT1 is a prognostic marker associated with immune invasion of bladder urothelial carcinoma

Plasmacytoma variant translocation 1 (PVT1) is involved in multiple signaling pathways and plays an important regulatory role in a variety of malignant tumors. However, its role in the prognosis and immune invasion of bladder urothelial carcinoma (BLCA) remains unclear. This study investigated the expression of PVT1 in tumor tissue and its relationship with immune invasion, and determined its prognostic role in patients with BLCA. Patients were identified from the cancer genome atlas (TCGA). The enrichment pathway and function of PVT1 were explained by gene ontology (GO) term analysis, gene set enrichment analysis (GSEA) and single-sample gene set enrichment analysis (ssGSEA), and the degree of immune cell infiltration was quantified. Kaplan-Meier analysis and Cox regression were used to analyze the correlation between PVT1 and survival rate. PVT1-high BLCA patients had a lower 10-year disease-specific survival (DSS P < 0.05) and overall survival (OS P < 0.05). Multivariate Cox regression analysis showed that PVT1 (high vs. low) (P = 0.004) was an independent prognostic factor. A nomogram was used to predict the effect of PVT1 on the prognosis. PVT1 plays an important role in the progression and prognosis of BLCA and can be used as a medium biomarker to predict survival after cystectomy.

Pterostilbene leads to DNMT3B-mediated DNA methylation and silencing of OCT1-targeted oncogenes in breast cancer cells

Transcription factor (TF)-mediated regulation of genes is often disrupted during carcinogenesis. The DNA methylation state of TF-binding sites may dictate transcriptional activity of corresponding genes. Stilbenoid polyphenols, such as pterostilbene (PTS), have been shown to exert anticancer action by remodeling DNA methylation and gene expression. However, the mechanisms behind these effects still remain unclear. Here, the dynamics between oncogenic TF OCT1 binding and de novo DNA methyltransferase DNMT3B binding in PTS-treated MCF10CA1a invasive breast cancer cells has been explored. Using chromatin immunoprecipitation (ChIP) followed by next generation sequencing, we determined 47 gene regulatory regions with decreased OCT1 binding and enriched DNMT3B binding in response to PTS. Most of those genes were found to have oncogenic functions. We selected three candidates, PRKCA, TNNT2, and DANT2, for further mechanistic investigation taking into account PRKCA functional and regulatory connection with numerous cancer-driving processes and pathways, and some of the highest increase in DNMT3B occupancy within TNNT2 and DANT2 enhancers. PTS led to DNMT3B recruitment within PRKCA, TNNT2, and DANT2 at loci that also displayed reduced OCT1 binding. Substantial decrease in OCT1 with increased DNMT3B binding was accompanied by PRKCA promoter and TNNT2 and DANT2 enhancer hypermethylation, and gene silencing. Interestingly, DNA hypermethylation of the genes was not detected in response to PTS in DNMT3B-CRISPR knockout MCF10CA1a breast cancer cells. It indicates DNMT3B-dependent methylation of PRKCA, TNNT2, and DANT2 upon PTS. Our findings provide a better understanding of mechanistic players and their gene targets that possibly contribute to the anticancer action of stilbenoid polyphenols.

Uncovering the stability status of the reputed reference genes in breast and hepatic cancer cell lines

Accurate and reliable relative gene expression analysis via the Reverse Transcription-quantitative Real Time PCR (RT-qPCR) method strongly depends on employing several stable reference genes as normalizers. Utilization of the reference genes without analyzing their expression stability under each experimental condition causes RT-qPCR analysis error as well as false output. Similar to cancerous tissues, cancer cell lines also exhibit various gene expression profiles. It is crucial to recognize stable reference genes for well-known cancer cell lines to minimize RT-qPCR analysis error. In this study, we showed the expression level and investigated the expression stability of eight common reference genes that are ACTB, YWHAZ, HPRT1, RNA18S, TBP, GAPDH, UBC, and B2M, in two sets of cancerous cell lines. One set contains MCF7, SKBR3, and MDA-MB231 as breast cancer cell lines. Another set includes three hepatic cancer cell lines, including Huh7, HepG2, and PLC-PRF5. Three excel-based softwares comprising geNorm, BestKeeper, and NormFinder, and an online tool, namely RefFinder were used for stability analysis. Although all four algorithms did not show the same stability ranking of nominee genes, the overall results showed B2M and ACTB as the least stable reference genes for the studied breast cancer cell lines. While TBP had the lowest expression stability in the three hepatic cancer cell lines. Moreover, YWHAZ, UBC, and GAPDH showed the highest stability in breast cancer cell lines. Besides that, a panel of five nominees, including ACTB, HPRT1, UBC, YWHAZ, and B2M showed higher stability than others in hepatic cancer cell lines. We believe that our results would help researchers to find and to select the best combination of the reference genes for their own experiments involving the studied breast and hepatic cancer cell lines. To further analyze the reference genes stability for each experimental condition, we suggest researchers to consider the provided stability ranking emphasizing the unstable reference genes.

Depleting SOX2 improves ischemic stroke via lncRNA PVT1/microRNA-24-3p/STAT3 axis

Objectives

Studies have widely explored in the filed of ischemic stroke (IS) with their focus on transcription factors. However, few studies have pivoted on sex determining region Y-box 2 (SOX2) in IS. Thus, this study is launched to figure out the mechanisms of SOX2 in IS.

Methods

Rat middle cerebral artery occlusion (MCAO) was established as a stroke model. MCAO rats were injected with depleted SOX2 or long non-coding RNA plasmacytoma variant translocation 1 (PVT1) to explore their roles in neurological deficits, cerebral water content, neuron survival, apoptosis and oxidative stress. The relationship among SOX2, PVT1, microRNA (miR)-24-3p and signal transducer and activator of transcription 3 (STAT3) was verified by a series of experiments.

Results

SOX2, PVT1 and STAT3 were highly expressed while miR-24-3p was poorly expressed in cerebral cortex tissues of MCAO rats. Depleted SOX2 or PVT1 alleviated brain injury in MCAO rats as reflected by neuronal apoptosis and oxidative stress restriction, brain water content reduction, and neurological deficit and neuron survival improvements. Overexpression of PVT1 functioned oppositely. Restored miR-24-3p abolished PVT1 overexpression-induced brain injury in MCAO rats. SOX2 directly promoted PVT1 expression and further increased STAT3 by sponging miR-24-3p.

Conclusion

This study presents that depleting SOX2 improves IS via PVT1/miR-24-3p/STAT3 axis which may broaden our knowledge about the mechanisms of SOX2/PVT1/miR-24-3p/STAT3 axis and provide a reference of therapy for IS.

LINC01410 leads the migration, invasion and EMT of bladder cancer cells by modulating miR-4319 / Snail1

Background

Several previous studies have implied the significance of lncRNA1410 (LINC01410) in gastric cancer, rectal cancer, and cervical cancer. Nevertheless, the potential of LINC01410 in bladder cancer (BC) development has not been addressed.

Methods

The related mechanisms were explored by qRT-PCR analysis, CCK-8 assay, cell transfection assay, Transwell assay, Western Blot analysis, Luciferase reporter assay and RNA pull-down assay.

Results

In the following study, LINC01410, characterized as an oncogene, exhibited high levels of expression in BC tissues as compared to normal tissues and its expression leads to a reduced prognosis of BC. Functional characterization of LINC01410 showed that knocking down LINC01410 could markedly reduce the invasion and proliferation capacity of T24 and 5637 cells. Mechanistically, LINC01410 served as a sponge for miR-4319 and the findings were further attested through luciferase reporter assay. Analysis of miR-4319 demonstrated its low expression in BC tissues as compared to normal tissues and knocking down LINC01410 significantly increased miR-4319. Data obtained from rescue assay discovered that silencing of miR-4319 in T24 and 5637 cells restored the proliferation and invasion capacity of LINC01410.

Conclusions

Taken together, this study is the first report on the oncogenic potential of LINC01410 in BC development by upregulating Snail1 protein and downregulating miR-4319.

Trial registration Retrospectively registered.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12935-021-02119-z.

STAT3-induced ZBED3-AS1 promotes the malignant phenotypes of melanoma cells by activating PI3K/AKT signaling pathway

Melanoma is considered as the most frequent primary malignancy occurring in skin. Accumulating studies have suggested that long non-coding RNAs (lncRNAs) play critical parts in multiple cancers. In this study, we explored the molecular mechanism of ZBED3 antisense RNA 1 (ZBED3-AS1) in melanoma. We observed that ZBED3-AS1 expression was remarkably up-regulated in melanoma tissues, and high ZBED3-AS1 level was linked to unsatisfactory survival of melanoma patients. Then, we discovered that ZBED3-AS1 was overexpressed in melanoma cells compared with human epidermal melanocytes. In addition, loss-of-function assays verified that ZBED3-AS1 knockdown restrained cell proliferation, migration, epithelial-mesenchymal transition (EMT), and stemness in melanoma. In addition, signal transducer and activator of transcription 3 (STAT3), which also showed tumour-facilitating functions in melanoma, was confirmed as a transcriptional activator of ZBED3-AS1. Moreover, ZBED3-AS1 enhanced the expression of AT-rich interaction domain 4B (ARID4B) through sequestering miR-381-3p. Importantly, we further confirmed that ZBED3-AS1 promoted the malignant progression of melanoma by regulating miR-381-3p/ARID4B axis to activate the phosphatidylinositol 3-kinase/AKT serine/threonine kinase (PI3K/AKT) signalling pathway. In a word, our research might provide a novel therapeutic target for melanoma.

Pterostilbene Changes Epigenetic Marks at Enhancer Regions of Oncogenes in Breast Cancer Cells

Epigenetic aberrations are linked to sporadic breast cancer. Interestingly, certain dietary polyphenols with anti-cancer effects, such as pterostilbene (PTS), have been shown to regulate gene expression by altering epigenetic patterns. Our group has proposed the involvement of DNA methylation and DNA methyltransferase 3B (DNMT3B) as vital players in PTS-mediated suppression of candidate oncogenes and suggested a role of enhancers as target regions. In the present study, we assess a genome-wide impact of PTS on epigenetic marks at enhancers in highly invasive MCF10CA1a breast cancer cells. Following chromatin immunoprecipitation (ChIP)-sequencing in MCF10CA1a cells treated with 7 μM PTS for 9 days, we discovered that PTS leads to increased binding of DNMT3B at enhancers of 77 genes, and 17 of those genes display an overlapping decrease in the occupancy of trimethylation at lysine 36 of histone 3 (H3K36me3), a mark of active enhancers. We selected two genes, PITPNC1 and LINC00910, and found that their enhancers are hypermethylated in response to PTS. These changes coincided with the downregulation of gene expression. Of importance, we showed that 6 out of 17 target enhancers, including PITPNC1 and LINC00910, are bound by an oncogenic transcription factor OCT1 in MCF10CA1a cells. Indeed, the six enhancers corresponded to genes with established or putative cancer-driving functions. PTS led to a decrease in OCT1 binding at those enhancers, and OCT1 depletion resulted in PITPNC1 and LINC00910 downregulation, further demonstrating a role for OCT1 in transcriptional regulation. Our findings provide novel evidence for the epigenetic regulation of enhancer regions by dietary polyphenols in breast cancer cells.

Identification and Roles of miR-29b-1-3p and miR29a-3p-Regulated and Non-Regulated lncRNAs in Endocrine-Sensitive and Resistant Breast Cancer Cells

Despite improvements in the treatment of endocrine-resistant metastatic disease using combination therapies in patients with estrogen receptor α (ERα) primary tumors, the mechanisms underlying endocrine resistance remain to be elucidated. Non-coding RNAs (ncRNAs), including microRNAs (miRNA) and long non-coding RNAs (lncRNA), are targets and regulators of cell signaling pathways and their exosomal transport may contribute to metastasis. Previous studies have shown that a low expression of miR-29a-3p and miR-29b-3p is associated with lower overall breast cancer survival before 150 mos. Transient, modest overexpression of miR-29b1-3p or miR-29a-3p inhibited MCF-7 tamoxifen-sensitive and LCC9 tamoxifen-resistant cell proliferation. Here, we identify miR-29b-1/a-regulated and non-regulated differentially expressed lncRNAs in MCF-7 and LCC9 cells using next-generation RNA seq. More lncRNAs were miR-29b-1/a-regulated in LCC9 cells than in MCF-7 cells, including DANCR, GAS5, DSCAM-AS1, SNHG5, and CRND. We examined the roles of miR-29-regulated and differentially expressed lncRNAs in endocrine-resistant breast cancer, including putative and proven targets and expression patterns in survival analysis using the KM Plotter and TCGA databases. This study provides new insights into lncRNAs in endocrine-resistant breast cancer.

Targeting PVT1 Exon 9 Re-Expresses Claudin 4 Protein and Inhibits Migration by Claudin-Low Triple Negative Breast Cancer Cells

PVT1 is a long non-coding RNA transcribed from a gene located at the 8q24 chromosomal region that has been implicated in multiple cancers including breast cancer (BC). Amplification of the 8q24 chromosomal region is a common event in BC and is associated with poor clinical outcomes. Claudin-low (CL) triple negative breast cancer (TNBC) is a subtype of BC with a particularly dismal outcome. We assessed PVT1 exon 9 expression in the T47D estrogen receptor positive BC cell line, and in the MDA MB 468 and MDA MB 231 TNBC cell lines, followed by the assessment of the expression of claudins 1, 3, 4 and 7, in MDA MB 468 and MDA MB 231 (TNBC) cells. We found that MDA MB 231 TNBC cells significantly express less claudin 1, 3, 4, and 7 than MDA MB 468 TNBC cells. PVT1 exon 9 is significantly upregulated in MDA MB 231 CL TNBC cells, and significantly downregulated in MDA MB 468 claudin high (CH) TNBC cells, in comparison to T47D estrogen receptor positive BC cells. We then analyzed the functional consequences of siRNA targeting of PVT1 exon 9 expression in the MDA MB 231 CL TNBC cells. Notably, siRNA targeting of PVT1 exon 9 expression in the MDA MB 231 CL TNBC cells led to a significant reduction in migration and the re-expression of claudin 4. Taken together, our data indicate that PVT1 exon 9 regulates claudin 4 expression and migration in CL TNBC cells, and may have clinical implications in CL TNBC.

The effects of LncRNA PVT1 on clinical characteristics and survival in breast cancer patients: A protocol for systematic review and meta analysis

BACKGROUND

Currently, an increasing number of long noncoding RNAs (LncRNAs) have been reported to be abnormally expressed in human carcinomas and play a vital role in tumourigenesis. Some studies were carried out to investigate the influence of the expression of plasmacytoma variant translocation 1 (PVT1) on prognosis and its clinical significance in patients with breast cancer, while the results were contradictory and uncertain. A meta-analysis was conducted with controversial data to accurately assess the issue.

METHODS

A detailed search of relevant researches was performed in Wanfang, Chinese Biomedical Literature Database, Chinese National Knowledge Infrastructure, Chongqing VIP Chinese Science and Technology Periodical Database, PubMed, Embase, and Web of Science. Two reviewers independently conducted data extraction and literature quality evaluation. Odd ratio and its 95% confidence intervals were applied to evaluate the relationship between PVT1 and clinicopathological characteristics of breast cancer patients. Hazard ratios and its 95% confidence intervals were adopted to assess the prognostic effects of PVT1 on overall survival and disease-free survival. Meta-analysis was conducted with Stata 14.0 software.

RESULTS

This study will provide high-quality evidence-based medical evidence for the correlation between PVT1 expression and overall survival, and disease-free survival and clinicopathological features.

CONCLUSION

The study will provide updated evidence to evaluate whether the expression of PVT1 is in association with poor prognosis in patients with breast cancer.

OSF REGISTRATION NUMBER

DOI 10.17605/OSF.IO/C2TYE.

SOX2 knockdown slows cholangiocarcinoma progression through inhibition of transcriptional activation of lncRNA PVT1

Cholangiocarcinoma (CCA) has accounted for a high rate of mortality and morbidity in the recent years. Long non-coding RNAs (lncRNAs) play an important role in different cellular environments, including cancer. As such, they have been used as potential targets during CCA therapy. The objective of this study was to investigate the effects of lncRNA PVT1 on CCA and its mechanisms behind lncRNA PVT1 regulation. The interactions among SOX2, lncRNA PVT1, miR-186 and SEMA4D were verified by chromatin immunoprecipitation, RNA immunoprecipitation and dual luciferase reporter gene assay. Gain- and loss-of-function experiments were conducted to explore the modulatory effects of SOX2, lncRNA PVT1, miR-186 and SEMA4D on cell viability, migration and invasion of CCA by CCK-8 and Transwell assays. In vivo effects of lncRNA PVT1 or SEMA4D were studied in a nude mouse model. MiR-186 was poorly expressed while SOX2, lncRNA PVT1 and SEMA4D were highly expressed in CCA cells. SOX2 induced the transcriptional activation of lncRNA PVT1 expression to promote proliferation, migration and invasion of CCA cells. LncRNA PVT1 bound to miR-186 and miR-186 was found to target SEMA4D. The overexpression of lncRNA PVT1 and SEMA4D, as well as the inhibition of miR-186 led to elevated CCA cell proliferation, migration and invasion. In vivo experiments confirmed the inhibitory role of lncRNA PVT1 knockdown or SEMA4D knockdown in CCA. All in all, SOX2 down-regulated miR-186 through the transcriptional activation of lncRNA PVT1, whereas elevating SEMA4D expression, thus promoting the progression of CCA.

PVT1: A long non-coding RNA recurrently involved in neoplasia-associated fusion transcripts

NGS technologies and bioinformatics tools allow the rapid identification of chimeric transcripts in cancer. More than 40,000 fusions are so far reported in the literature; however, for most of them, the role in oncogenesis is still not fully understood. This is the case for fusions involving the long non-coding RNA (lncRNA) Plasmacytoma variant translocation 1 (PVT1) (8q24.21). This lncRNA displays oncogenic functions in several cancer types interacting with microRNAs and proteins, but the role of PVT1 fusion transcripts is more obscure. These chimeras have been identified in both hematological malignancies and solid tumors, mainly arising from rearrangements and/or amplification of the 8q24 chromosomal region. In this review, we detail the full spectrum of PVT1 fusions in cancer, summarizing current knowledge about their genesis, function, and role as biomarkers.

Knockdown of LINC00504 Inhibits the Proliferation and Invasion of Breast Cancer via the Downregulation of miR-140-5p

INTRODUCTION

Breast cancer is one of the most common cancers in the world. Long noncoding RNA 00504 (LINC00504) was reported to be a functional gene in some tumours but not breast. Accordingly, the purpose of this article is to study the function of LINC00504 in breast cancer.

METHODS

qPCR assay was used to detect the expression of LINC00504 in tissue and cell lines. The online database and chromatin immunoprecipitation assay (ChIP) were employed to confirm the transcription factor of LINC00504. Cell function assays including cell proliferation, migration and invasion were designed to detect the function of LINC00504 in vitro and in vivo. Luciferase reporter assay and RNA immunoprecipitation (RIP) assay were used to confirm the relationship between LINC00504 and miR-140-5p. And Western blot assay was employed for testing the key protein.

RESULTS

We found that LINC00504 is upregulated in breast cancer. In addition, we found that the transcription factor regulatory factor X5 (RFX5) can strongly bind to the LINC00504 promoter region and subsequently increase its transcriptional activity. We also found that the manipulation of RFX5 expression can significantly affect LINC00504 expression, which suggested that RFX5 can transcriptionally activate LINC00504 in breast cancer (BC). Knockdown of LINC00504 inhibits cell proliferation, migration and invasion in vitro and in vivo. We further found that LINCOO504 inhibits miR-140-5p, which decreases the levels of VEGFA. The further results showed that miR-140-5p was one of the target gene of LINC00504. The WB assay demonstrated that the E-cadherin was increased and Vimentin was decreased when knocking down of LINC00504 and they can be rescued while adding the inhibitors of miR-140-5p.

DISCUSSION

Our results demonstrated the mechanism by which the LINC00504-miR-140-5p-VEGFA axis participates in breast cancer cell proliferation and invasion and may lead to new lncRNA-based diagnostic or therapeutic strategies for breast cancer.

Metformin modulates oncogenic expression of HOTAIR gene via promoter methylation and reverses epithelial-mesenchymal transition in MDA-MB-231 cells

Epithelial-mesenchymal transition (EMT) is a biological event, which critically regulates migration and invasion of cancer cells. EMT is regulated by several protein and nonprotein factors (such as noncoding RNAs). HOTAIR is an oncogenic long noncoding RNA that stimulates EMT in cancers. In the current study, we investigated the effect of metformin on EMT behavior and HOTAIR expression in MDA-MB-231 breast cancer cells. The minimal effective concentrations of metformin (10 and 20 mM) were obtained by the MTT test. Cell migration and invasion in the metformin-containing medium were assayed in the scratch assay and transwell test. Meaningful decreases in both cell migration and invasion were observed in the presence of metformin. Vimentin, snail, β-catenin, and HOTAIR transcripts were quantified by real-time polymerase chain reaction (PCR). Reduction in the expression of vimentin, β-catenin, and HOTAIR was detected as the result of metformin treatment, but the snail showed a constant expression. Western blottingrevealed the downregulation of vimentin and β-catenin proteins. HOTAIR promoter methylation pattern was also investigated in metformin-exposed cells using bisulfite sequencing PCR which the result showed differences in the methylation profile of CpG islands between the treated and untreated cells. In conclusion, metformin modulated oncogenic expression of the HOTAIR gene in the MDA-MB-231 cells. This downregulation was associated with the modification of promoter methylation patterns. Since HOTAIR induces EMT in breast cancer, HOTAIR decline might be one of the mechanisms by which metformin reverses EMT.

Long non-coding RNA TMPO-AS1 promotes tumor progression via sponging miR-140-5p in breast cancer

Long non-coding RNAs (lncRNAs) are involved in carcinogenesis and tumor suppression, and are novel biological tumor regulators. However, the functional roles of lncRNAs and their underlying dysregulation mechanisms in breast cancer are not completely understood. The aim of the present study was to investigate the clinical significance and biological functions of lncRNA TMPO antisense RNA 1 (TMPO-AS1) in breast cancer. TMPO-AS1 levels were measured in human cancer tissues and breast cancer cell lines, and the functional roles of TMPO-AS1 in breast cancer cells were investigated by performing in vitro and in vivo assays. Additionally, luciferase reporter assays were conducted to detect the association between microRNA (miR)-140-5p and TMPO-AS1. TMPO-AS1 expression levels were significantly increased in breast cancer tissues and cell lines compared with adjacent non-cancerous tissues and MCF-10A cells, respectively. In vitro and in vivo studies indicated that TMPO-AS1 knockdown significantly suppressed breast cancer cell viability at 48 and 72 h compared with the small interfering (si)RNA negative control group (NC; siNC). TMPO-AS1 knockdown in vitro inhibited MCF-7 and T47D cell migration and invasion compared with the siNC group. TMPO-AS1 knockdown in metastatic breast cancer cells also decreased metastatic colonization in the mouse lung compared with the short hairpin RNA NC group. Mechanistically, TMPO-AS1 promoted cellular viability and migration as a competing endogenous RNA by sponging miR-140-5p. The results suggested that TMPO-AS1 may serve as a potential therapeutic target in patients with breast cancer.

lncRNA PART1 Promotes Breast Cancer Cell Progression by Directly Targeting miR-4516

Introduction

Breast cancer is a serious threat to human health. It is meaningful to study the pathogenesis of breast cancer. lncRNAs have been found to play vital roles in numerous biological processes including development, immunology and cancer.

Methods

qRT-PCR was performed to examine the expressions of PART1 and miR-4516. CCK-8 assay, colony formation assay and transwell assay were used to examine the progression of breast cancer cells.

Results

In this study, we showed that lncRNA PART1 was highly expressed in breast cancer cells. Knockdown of PART1 induced decreased proliferation, invasion and migration of breast cancer cells. Moreover, we found that PART1 can bind to miR-4516 directly. We also found that inhibition of miR-4516 could rescue the decreased proliferation, migration and invasion of breast cancer cells induced by knockdown of PART1.

Discussion

lncRNA PART1 and miR-4516 were proven to be involved in the progression of many cancers. However, the roles of lncRNA PART1 and miR-4516 in the regulation of breast cancer remain unknown. Here, we demonstrated that PART1 can bind to miR-4516 to decrease the expression of miR-4516 and promote the development of breast cancer.

Unleash multifunctional role of long noncoding RNAs biomarker panel in breast cancer: a predictor classification model

Aim: We aimed to explore the circulating expression profile of nine lncRNAs (MALAT1, HOTAIR, PVT1, H19, ROR, GAS5, ANRIL, BANCR, MIAT) in breast cancer (BC) patients relative to normal and risky individuals. Methods: Serum relative expressions of the specified long non-coding RNAs were quantified in 155 consecutive women, using quantitative reverse-transcription PCR. Random Forest (RF) and decision tree were also applied. Results: Significant MALAT1 upregulation and GAS5 downregulation could discriminate risky women from healthy controls. Overexpression of the other genes showed good diagnostic performances. Lower GAS5 levels were associated with metastasis and recurrence. RF model revealed a better performance when combining gene expression patterns with risk factors. Conclusion: The studied panel could be utilized as diagnostic/prognostic biomarkers in BC, providing promising epigenetic-based therapeutic targets.

ZNF367-induced transcriptional activation of KIF15 accelerates the progression of breast cancer

Breast cancer (BC) is one of the most common female cancers, and its incidence has been increasing in recent years. Although treatments are continuously improving, the prognosis of patients in the advanced stage is still unsatisfactory. Thus, an in-depth understanding of its molecular mechanisms is necessary for curing breast cancer. KIF15 is a tetrameric spindle motor which can regulate mitosis in cellular process and exert the crucial functions in several cancers. The purpose of our research was to investigate the functions of KIF15 in breast cancer. We tested the expression of KIF15 in breast cancer tissues and the survival rate of breast cancer patients with high or low level of KIF15 through TCGA data. What's more, western blot and immunohistochemistry assay were utilized to evaluate the protein level and mRNA level of KIF15 in breast cancer tissues. Then CCK-8, wound healing, transwell and flow cytometry experiments were adopted separately to test cell viability, migration, invasion and cell cycle distribution. We discovered that KIF15 was highly expressed in breast cancer tissues and high level KIF15 was associated with a low survival rate of breast cancer patients. Moreover, silence of KIF15 suppressed cell viability, migration, invasion and cell cycle distribution. Following, we discovered that ZNF367 was the upstream transcription factor of KIF15. In addition, silenced ZNF367 could also repress the growth of breast cancer cells. And rescue experiments indicated that overexpressed KIF15 could counteract the inhibition effect of silencing ZNF367 on the progression of breast cancer. Importantly, we discovered that KIF15 and ZNF367 were associated with the regulation of cell cycle. In short, ZNF367-activated KIF15 accelerated the progression of breast cancer by regulating cell cycle progress.

Development of a nine-lncRNA signature as a novel prognostic marker of estrogen receptor-negative breast cancer

Long non-coding RNAs (lncRNAs) have been demonstrated to be aberrantly expressed in several types of tumor, and dysregulated lncRNAs are suggested to play a prognostic role in breast cancer (BC). Estrogen receptor (ER) status is a prognostic factor in patients with ER-negative BC, which is associated with poor prognosis. Thus, the present study developed a prognostic lncRNA signature specifically for ER-negative BC, in order to predict the risk of post-surgery relapse and improve patient prognosis. A gene expression profile containing 1,631 lncRNAs was obtained by investigating and integrating publicly available cohorts of BC. Subsequently, a nine-lncRNA signature was developed and validated in two independent cohorts via the Cox regression model. Using the nine-lncRNA signature, patients in the discovery cohort were divided into high- and low-risk groups, with significantly different disease-free survival [DFS; hazard ratio (HR)=2.718, 95% confidence interval (CI)=2.115-3.494, P<0.0001]. Receiver operating characteristic curve analyses demonstrated that the area under the curve reached 0.908. Similar results were obtained in the two independent cohorts (HR=1.499, 95% CI=0.950-2.365, P=0.04; HR=1.262, 95% CI=1.056-1.510, P=0.01), respectively. Furthermore, the nine lncRNAs were demonstrated to play important roles in the cell invasion and metastasis of different types of tumor. The differentially expressed genes (DEGs) identified between the high- and low-risk groups were consistently high in the discovery and validation cohorts. Functional analysis indicated that these DEGs, as well as genes co-expressed with the nine lncRNAs, were involved in cancer-associated signaling pathways, all of which provide further evidence for the predictive ability of the nine-lncRNA signature. Overall, the present study developed a novel prognostic biomarker for ER-negative BC.

Long noncoding RNA RHPN1-AS1 promotes colorectal cancer progression via targeting miR-7-5p/OGT axis

Background

Rhophilin Rho GTPase binding protein 1 antisense RNA 1 (RHPN1-AS1) is a newly discovered oncogene in several diseases, such as breast cancer, non-small cell lung cancer and uveal melanoma. Nevertheless, its molecular role in colorectal cancer (CRC) remains unknown. This paper explored the role of RHPN1-AS1 in CRC progression.

Methods

qRT-PCR was used to detect relevant RNAs expression. CCK-8, EdU, flow cytometry, Transwell and western blot assays were performed to investigate the function of RHPN1-AS1 in CRC cells. Xenograft model was constructed to evaluate the effects of RHPN1-AS1 on tumor growth in vivo. Mechanical experiments were performed to investigate the relationship between relative genes.

Results

RHPN1-AS1 was significantly overexpressed in CRC cell lines. Knockdown of RHPN1-AS1 could inhibit cell proliferation, while stimulating cell apoptosis in vitro. Cell migration and invasion abilities were greatly suppressed after silencing RHPN1-AS1. Besides, signal transducer and activator of transcription 3 (STAT3) served as transcription factor of RHPN1-AS1. Moreover, miR-7-5p was identified as a target of RHPN1-AS1 and was negatively regulated by RHPN1-AS1 in CRC. MiR-7-5p inhibition rescued the oncogenic function of RHPN1-AS1. Additionally, O-GlcNAcylation transferase (OGT) was the downstream target of miR-7-5p. OGT overexpression could abrogate the anti-tumor effects of RHPN1-AS1 knockdown on CRC.

Conclusion

RHPN1-AS1 regulates CRC by mediating OGT through sponging miR-7-5p, suggesting that RHPN1-AS1 might be a potential therapeutic target for CRC.

Tcf3-activated lncRNA Gas5 regulates newborn mouse cardiomyocyte apoptosis in diabetic cardiomyopathy

Diabetic cardiomyopathy can cause cardiac dysfunction and eventually lead to heart failure and sudden death. Long noncoding RNA (lncRNA) Gas5 has been reported to play a function in cardiomyocyte. Here we studied the function of Gas5 on newborn mouse cardiomyocyte (NMC) apoptosis to detect its molecular mechanism. High-glucose treatment was implemented to induce the apoptosis of NMC in this study. And terminal deoxynucleotidyl transferase dUTP nick-end labeling assay, JC-1 assay, and flow cytometry analysis were conducted to know about the apoptosis of NMC when Gas5 and Tcf3 were silenced. Meanwhile, RNA pull-down assay and luciferase reporter assay were conducted to verify the binding of RNAs. Finally, rescue assay was implemented to evaluate the influence on apoptosis situation affected by competing endogenous RNA pathways. Tcf3 was found to bind to the Gas5 promoter to activate the expression of Gas5. Meanwhile, Gas5 and Tcf3 were both found to promote the apoptosis of NMC. Also, mmu-miR-320-3p could bind to Gas5 and Tcf3. Moreover, the Gas5/miR-320-3p/Tcf3 pathway was found to modulate the apoptosis of NMC. In conclusion, Tcf3-activated lncRNA Gas5 regulates NMC apoptosis in diabetic cardiomyopathy.

ALKBH5-mediated m6A demethylation of lncRNA PVT1 plays an oncogenic role in osteosarcoma

Background

Osteosarcoma (OS) is one of the most common malignant bone tumors. Plasmacytoma variant translocation 1 (PVT1) is a well-known oncogenic long noncoding RNA (lncRNA). However, to date, the regulatory mechanism of PVT1 upregulation in OS remains unknown.

Methods

qRT-PCR was carried out to test the expression level of PVT1 and ALKBH5. RNA immunoprecipitation (RIP) and RNA pull-down assays were performed to detect the interaction of PVT1 with ALKBH5 and YTHDF2. Methylated RNA immune-precipitation (MeRIP) was used to examine the N⁶-methyladenosine (m⁶A) modification of PVT1 transcript.

Results

In this study, we found that PVT1 expression was upregulated in OS tissues and cells and significantly related with clinical stage, tumor size, and prognosis of patients with OS. Further investigation revealed that N⁶-methyladenosine (m⁶A) demethylase ALKBH5 could associate with PVT1 and suppress its degradation. ALKBH5 decreased the m⁶A modification of PVT1, thus inhibiting the binding of reader protein YTHDF2 in PVT1. Functionally, ALKBH5-mediated PVT1 upregulation promoted the OS cell proliferation in vitro and tumor growth in vivo.

Conclusions

Our study suggests that ALKBH5-mediated m⁶A modification of PVT1 contributes to OS tumorigenesis.

Long noncoding RNA PVT1 acts as an oncogenic driver in human pan-cancer

Increasing evidence indicates that long noncoding RNAs (lncRNAs) play pivotal roles during tumorigenesis in multiple types of cancers. However, little is known about the exact role of plasmacytoma variant translocation 1 (PVT1) in human pan-cancer. Here, we report the oncogenic role and function of PVT1 in human pan-cancer, including breast cancer. The expression of PVT1 in human tumor tissues and nontumor tissues, the upstream regulation of PVT1 and the relationship between its expression and prognosis and chemoresistance were examined by using The Cancer Genome Atlas data. PVT1 expression is higher in human cancer tissues compared with adjacent noncancerous tissues, and patients with high levels of PVT1 expression usually have tumors with a higher TNM stage. High PVT1 expression is also associated with worse disease outcomes in patients with cancer. Hypomethylation and transcription factor binding in the PVT1 promoter locus activates its transcriptional expression. Guilt by association analysis revealed that PVT1 may be involved in processes associated with tumorigenesis. Moreover, PVT1 may trigger chemoresistance in human cancer. These results indicated that PVT1 may act as an oncogenic driver and maybe a potential therapeutic target in human cancer.

Polymorphisms in the PVT1 Gene and Susceptibility to the Lung Cancer in a Chinese Northeast Population: a Case-control Study

Background: Long non-coding RNA (lncRNA) PVT1 has been identified to be related to risk of a variety of cancers, such as gastric cancer, pancreatic cancer and follicular lymphoma. This study assesses the association between genetic polymorphisms of PVT1 and the susceptibility to lung cancer as well as gene-environmental interaction. Method: A hospital-based case-control study, including 515 lung cancer patients and 582 healthy controls, was carried out in Shenyang, China. Unconditional logistic regression analyses calculated the odds ratios (ORs) and their 95% confidence intervals (CIs) to assess the associations between polymorphisms of rs2608053, rs1561927, rs13254990 and susceptibility to lung cancer. The gene-environment interaction was evaluated by additive model and multiplicative model. Results: There were no statistically significant associations between rs2608053 and rs1561927 polymorphisms in PVT1 and risk of lung cancer in the overall population. The relationship between polymorphism rs13254990 in PVT1 gene and lung adenocarcinoma was significant. Composed with individuals carrying CC genotypes, TT genotype carriers were more likely to develop lung adenocarcinoma (adjusted OR=2.095; 95%CI=1.084-4.047, P=0.028). In the recessive model, it also showed a statistically significant difference (TT vs CT+CC: adjusted OR=2.251, 95%CI=1.174-4.318, P=0.015). In nonsmokers, individuals carrying genotype CT had a lower risk of lung cancer than those with CC genotype (adjusted OR=0.673, 95%CI=0.472-0.959, P=0.028). Comparing with the homozygous CC, the patients with the heterozygous CT had a lower risk of NCSLC in the non-smoking group (adjusted OR =0.685, 95%CI=0.477-0.984, P=0.040). Additionally, gene-environment interaction results were not statistically significant in either additive model or multiplicative model. Conclusion: The polymorphism rs13254990 in PVT1 gene is associated with the risk of lung adenocarcinoma in a Chinese northeast population.

TLR5: A prognostic and monitoring indicator for triple-negative breast cancer

A novel, highly selective biomarker is urgently needed to predict and monitor triple-negative breast cancer (TNBC) because targeting molecules are not currently available. Although associated with various malignant tumors, the role of toll-like receptor 5 (TLR5) in TNBC remains uncertain. We aimed to define the effects of TLR5 in TNBC to determine whether it could serve as a prognostic and monitoring indicator for TNBC. We established TNBC cell line 4T1 with low TLR5 expression (GFP tag; TLR5⁻ 4T1) and with normal TLR5 expression (GFP tag; TLR5⁺ 4T1) using lentivirus-shRNA-TLR5 knockdown transfection and negative lentivirus transfection, respectively. Detected by western blot and qPCR, we found knockdown of TLR5 resulted in decreased expression of TLR5 and E-cadherin and increased expression of N-cadherin, vimentin, fibronectin, TRAF6, SOX2, and Twist1, which were related to EMT (epithelial–mesenchymal transition). In addition, downregulation of TLR5 increased the invasion and migration of 4T1 cells in vitro, which were investigated by CCK-8 and wound healing, as well as transwell assay and colony formation. Furthermore, the metastatic ability of TLR5⁻ 4T1 cells to the lungs was also increased compared to TLR5⁺ 4T1 cells in vivo. To verify the effect of TLR5 as a monitor indicator, mice bearing TLR5⁺ and TLR5⁻ 4T1 tumors injected with ¹²⁵I-anti-TLR5 mAb or isotype ¹²⁵I-IgG were assessed by whole body phosphor-autoradiography and fluorescence imaging in vivo. Phosphor-autoradiography of model mice revealed early tumors at 6 days after inoculation with TLR5⁺ 4T1, but not TLR5⁻ 4T1 cells. Intratumoral accumulation of radioactivity positively correlated with TLR5 expression, and fluorescence imaging in vivo revealed both TLR5⁺ and TLR5⁻ 4T1 tumors. Our results suggested that downregulation of TLR5 in TNBC increased tumor invasiveness and EMT expression via TRAF6 and SOX2 pathway and TLR5 could serve as a prognostic and monitoring indicator for TLR5-positive tumors.

Long Non-Coding RNA Plasmacytoma Variant Translocation 1 (PVT1) Enhances Proliferation, Migration, and Epithelial-Mesenchymal Transition (EMT) of Pituitary Adenoma Cells by Activating β-Catenin, c-Myc, and Cyclin D1 Expression

BACKGROUND As a kind of benign tumor, pituitary adenomas have attracted increasing attention from researchers. The plasmacytoma variant translocation 1 (PVT1) is a molecule in the lncRNA family protein that has been proven to play critical roles in many cancers; however, no study has explored the special biological roles of PVT1 in pituitary adenoma. MATERIAL AND METHODS The qRT-PCR assay was conducted to evaluate PVT1 expressions in various cell lines and tissues. Loss of function assays were carried out to detect the influence of silenced PVT1 on the proliferation, migration, and epithelial-mesenchymal transition (EMT) of pituitary adenoma cells. Western blotting was used to identify correlation between ß-catenin and PVT1. RESULTS The PVT1 expressions were significantly enhanced in tissues of pituitary adenoma and cancer cells. Cell migration and proliferation were inhibited when the PVT1 gene was knocked down. Knockdown of PVT1 repressed the migration and EMT of pituitary adenoma cells. The PVT1 downregulation obviously blocked Wnt/ß-catenin signaling pathway activity. PVT1 aggravated progression of pituitary adenoma through initiating the Wnt/ß-catenin signaling pathway. CONCLUSIONS PVT1 exerts an oncogenic role through activating Wnt/ß-catenin signaling in pituitary adenoma cells. The present results may provide a potential therapeutic target or approach for treating pituitary adenomas.

Long noncoding RNAs and exosomal lncRNAs: classification, and mechanisms in breast cancer metastasis and drug resistance

Breast cancer is the most common cancer, and the second cause of cancer-related deaths (after lung cancer) among women. Developing tumor metastasis and invasion is the most important cause of death in breast cancer patients. Several key factors participate in breast cancer metastasis including long noncoding RNAs (lncRNAs). lncRNAs are a category of cellular RNAs that are longer than 200 nucleotides in length. Accumulating evidence suggests that lncRNAs have the potential to be promising diagnostic, prognostic biomarkers and therapeutic targets in breast cancer. Understanding the role of lncRNAs and their mechanisms of functions might help to further discovery of breast cancer biological characteristics. In this review, we discuss physiological functions, epigenetic regulation, transcriptional regulation of lncRNAs, and their important role in tumor progression and metastasis. Some lncRNAs function as oncogenes and some function as tumor suppressors. Interestingly, recent reports depict that hypomethylation of promoters of lncRNAs play a pivotal role in cancer progression, suggesting the importance of epigenetic regulation. Furthermore, we discuss the role of lncRNAs in exosomes and their function in drug resistance, and therapeutic importance of exosomal lncRNAs in cancer biology. In summary, lncRNAs have a great potential to consider them as novel prognostic biomarkers as well as new therapeutic targets in breast cancer.

SOX2-induced upregulation of lncRNA LINC01510 promotes papillary thyroid carcinoma progression by modulating miR-335/SHH and activating Hedgehog pathway

LncRNA LINC01510 (LINC01510) was a newly identified tumor-related lncRNA whose dysregulation and potential function have been reported in several tumors. However, the expression, clinical significances, and action mechanisms of LINC01510 in papillary thyroid carcinoma (PTC) are still unclear. In this study, we firstly reported that LINC01510 was highly expressed in both PTC tissues and cell lines. Additionally, we used dual-luciferase reporter assay and confirmed that SOX2 could bind directly to the LINC01510 promoter region, activating its transcription. Functional assays with a series of cell experiments indicated that knockdown of LINC01510 suppressed the proliferation, migration and invasion of SW1736 and TPC-1 cells. Moreover, down-regulation of LINC01510 resulted in accelerated apoptosis by promoting the expression of Caspase3/9. In particular, LINC01510 acted as an endogenous sponge by directly binding miR-335, resulting in the suppression of miR-335 expressions. Besides, we confirmed that SHH was a target of miR-335 and miR-335 over-expression distinctly reduced SHH expression in PTC cells. Finally, in the cytoplasm, we provided evidenced that LINC01510 acted as a sponge for miR-335, reducing its ability to promote SHH expression. In addition, the results of Western blot indicated that knockdown of LINC01510 inhibited the expression of SHH and GLI1, suggesting that Hedgehog pathway was suppressed. Taken together, our findings revealed that the newly identified LINC01510/miR-335/SHH axis could be a therapeutic target for PTC.

SOX2 promotes hypoxia-induced breast cancer cell migration by inducing NEDD9 expression and subsequent activation of Rac1/HIF-1α signaling

Background

Hypoxia, a major condition associated with the tumor microenvironment, stimulates the migration of cancer cells. SOX2 is a powerful transcription factor that shows higher expression in several cancers, however, its role in hypoxia-induced breast cancer cell migration remains largely elusive.

Methods

The human breast cancer cell lines MDA-MB-231 and MDA-MB-468 were cultured under hypoxic conditions. The cell migration rate was determined using the wound-healing and transwell assays. The protein levels of SOX2, NEDD9 and HIF-1α were evaluated via western blotting analysis. The NEDD9 mRNA levels were evaluated using qPCR. The activation of Rac1 was detected with the pulldown assay. The binding of SOX2 to the NEDD9 promoter was checked using the luciferase reporter assay. We also transfected breast cancer cells with specific siRNA for SOX2, NEDD9 or the Rac1 inactive mutant (T17 N) to investigate the role of SOX2, NEDD9 and Rac1 in the response to hypoxia.

Results

Hypoxia markedly increased SOX2 protein levels in a time-dependent manner. SiRNA-mediated disruption of SOX2 inhibited cell migration under hypoxic conditions. Hypoxia also significantly augmented the NEDD9 mRNA and protein levels. Interestingly, SOX2 is a positive transcriptional regulator of NEDD9. Knockdown of SOX2 inhibited hypoxia-induced NEDD9 mRNA and protein expressions. Furthermore, hypoxia-induced upregulation of Rac1 activity and HIF-1α expression was attenuated by SOX2 or NEDD9 silencing, and Rac1-T17 N abolished HIF-1α expression as well as cell migration in cells subjected to hypoxia.

Conclusions

Our results highlight the essential role of SOX2 in breast cancer cell motility. The upregulation of SOX2 under hypoxic conditions may facilitate NEDD9 transcription and expression, and subsequent activation of Rac1 and HIF-1α expression. This could accelerate breast cancer cell migration.

Regulatory Mechanisms and Clinical Applications of the Long Non-coding RNA PVT1 in Cancer Treatment

Cancer is the second leading cause of death worldwide, and no obvious decline in incidence and mortality has occurred in recent years. It is imperative to further investigate the mechanisms underlying tumor progression. Long non-coding RNAs have received considerable attention in recent years because of their major regulatory roles in gene expression. Among them, PVT1 is well-studied, and substantial evidence indicates that PVT1 plays critical roles in the onset and development of cancers. Normally, PVT1 acts as an oncogenic factor by promoting cancer cell proliferation, invasion, metastasis, and drug resistance. Herein, we summarize current knowledge regarding the regulatory effects of PVT1 in cancer progression, as well as the related underlying mechanisms, such as interaction with Myc, modulation of miRNAs, and regulation of gene transcription and protein expression. In extracellular fluid, PVT1 mainly promotes cancer initiation, and it normally enhances cellular cancer characteristics in the cytoplasm and cell nucleus. Regarding clinical applications, its role in drug resistance and its potential use as a diagnostic and prognostic marker have received increasing attention. We hope that this review will contribute to a better understanding of the regulatory role of PVT1 in cancer progression, paving the way for the development of PVT1-based therapeutic approaches in cancer treatment.

Long noncoding RNA PVT1: A highly dysregulated gene in malignancy

Recent studies have verified the contribution of several long noncoding RNAs (lncRNAs) in the carcinogenesis. Among the highly acknowledged lncRNAs is the human homolog of the plasmacytoma variant translocation gene, which is called PVT1. PVT1 resides near Myc oncogene and regulates the oncogenic process through modulation of several signaling pathways, such as TGF-β, Wnt/ β-catenin, PI3K/AKT, and mTOR pathways. This lncRNA has a circular form as well. Expression analyses and functional studies have appraised the oncogenic roles of PVT1 and circPVT1. Experiments in several cancer cell lines have shown that PVT1 silencing suppresses cancer cell proliferation, whereas its overexpression has the opposite effect. Its silencing has led to the accumulation of cells in the G0/G1 phase and diminished the number of cells in the S phase. Moreover, genome-wide association studies have signified the role of single nucleotide polymorphisms of this lncRNA in conferring risk of lymphoma in different populations. In the current study, we have summarized recent data about the role of PVT1 and circPVT1 in the carcinogenesis process.

Prognostic value of long non-coding RNA plasmacytoma variant translocation1 in human solid tumors: A meta-analysis

Plasmacytoma variant translocation 1 (PVT1) is highly expressed in a variety of cancer tissues and is related to the clinicopathological features and prognosis. However, the prognostic value of PVT1 is still controversial. Therefore, this systematic evaluation and meta-analysis were performed to evaluate the relationship between PVT1 expression and clinicopathological features.PubMed, EMBASE, Web of science, and Cochrane library databases were searched for literature collection according to inclusion criteria and exclusion criteria. The pooled hazard ratios (HRs) or odds ratios (ORs) were used to evaluate the association between PVT1 expression and overall survival, tumor size, tumor-node-metastasis (TNM) stage, lymph node metastasis, and distant metastasis.A total of 39 articles including 3974 patients were included in the study. The results showed that the expression of PVT1 was closely related to the overall survival rate of cancers (HR = 1.64, 95% confidence interval [CI]: 1.50-1.78, P < .000001). Subgroup analysis showed that the high expression of PVT1 was closely related to the low overall survival rate of patients with clear cell renal cell carcinoma, breast cancer, cervical cancer, colon cancer, epithelial ovarian cancer, gastric cancer, lung cancer, and osteosarcoma. In addition, the high expression of PVT1 was positively correlated with tumor size (OR = 1.50, 95% CI: 1.14-1.96, P = .004), TNM stage (OR = 3.39, 95% CI: 2.73-4.20, P < .00001), lymph node metastasis (OR = 2.60, 95% CI: 1.76-3.84, P < .00001), and distant metastasis (OR = 2.94, 95% CI: 1.90-4.56, P < .00001).PVT1 could serve as a marker for the size, TNM stage, metastasis, and prognosis of different type of cancers.

lncRNA ATXN8OS promotes breast cancer by sequestering miR‑204

Breast cancer (BC) is a common malignancy among women and the leading cause of female cancer mortality worldwide. In recent years, increasing evidence has shown that long non-coding RNAs (lncRNAs) can act as competing endogenous RNAs (ceRNAs) in human cancer and that they are involved in many biological processes, including proliferation, migration, apoptosis and invasion. In the present study, the biological function and molecular mechanism of ataxin 8 opposite strand (ATXN8OS) in BC tissue and cell lines were investigated. It was found that ATXN8OS was markedly up-regulated in BC tissue and cell lines, and that its level of overexpression was inversely linked with the overall survival rate of patients with BC. Knockdown of ATXN8OS inhibited proliferation, viability and invasion in the human MCF7 and MDA-MB-231 BC cell lines. In addition, microRNA-204 (miR-204) was negatively associated with the expression of ATXN8OS in BC tissues and cell lines. A luciferase assay demonstrated a direct binding site for miR-204 within ATXN8OS, and inhibition of miR-204 stimulated the tumour-promoting effect of ATXN8OS on BC cells. In conclusion, the present study suggested that ATXN8OS acts as a tumour promoter by sequestering miR-204 during the development of BC, therefore providing a mechanistic insight which may facilitate the diagnosis and treatment of BC.

The role of SOX family members in solid tumours and metastasis

Cancer is a heavy burden for humans across the world with high morbidity and mortality. Transcription factors including sex determining region Y (SRY)-related high-mobility group (HMG) box (SOX) proteins are thought to be involved in the regulation of specific biological processes. The deregulation of gene expression programs can lead to cancer development. Here, we review the role of the SOX family in breast cancer, prostate cancer, renal cell carcinoma, thyroid cancer, brain tumours, gastrointestinal and lung tumours as well as the entailing therapeutic implications. The SOX family consists of more than 20 members that mediate DNA binding by the HMG domain and have regulatory functions in development, cell-fate decision, and differentiation. SOX2, SOX4, SOX5, SOX8, SOX9, and SOX18 are up-regulated in different cancer types and have been found to be associated with poor prognosis, while the up-regulation of SOX11 and SOX30 appears to be favourable for the outcome in other cancer types. SOX2, SOX4, SOX5 and other SOX members are involved in tumorigenesis, e.g. SOX2 is markedly up-regulated in chemotherapy resistant cells. The SoxF family (SOX7, SOX17, SOX18) plays an important role in angio- and lymphangiogenesis, with SOX18 seemingly being an attractive target for anti-angiogenic therapy and the treatment of metastatic disease in cancer. In summary, SOX transcription factors play an important role in cancer progression, including tumorigenesis, changes in the tumour microenvironment, and metastasis. Certain SOX proteins are potential molecular markers for cancer prognosis and putative potential therapeutic targets, but further investigations are required to understand their physiological functions.

Prognostic values of long noncoding RNA PVT1 in various carcinomas: An updated systematic review and meta-analysis

Cancers have been a worldwide health problem with a high mortality rate, but ideal biomarkers are not available to effectively screen and diagnose patients. Currently, an increasing number of long noncoding RNAs have been reported to be abnormally expressed in human carcinomas and play a vital role in tumourigenesis. Plasmacytoma variant translocation 1 (PVT1) is upregulated in various carcinomas, and its overexpression is associated with poor survival in cancer patients. We conduct an updated meta-analysis to determine its potential in prognosis for tumours. In total, 14 studies comprising 2435 patients were enrolled according to Reporting Recommendations for Tumour Marker Prognostic Studies guidelines. High PVT1 expression indicated poor overall survival (hazard ratio [HR] = 1.98, 95% confidence interval [CI]: 1.62-2.42, P < 0.00001) and disease-free survival (HR = 1.63, 95% CI: 1.45-1.84, P < 0.00001). Additionally, increased PVT1 expression was positively associated with lymphatic node metastasis (odd ratio [OR] = 2.87, 95% CI: 1.66-4.96, P = 0.0002), distant metastasis (OR = 2.47, 95% CI: 1.74-3.50, P < 0.00001), advanced tumour-node-metastasis stages (OR = 2.59, 95% CI: 1.38-4.88, P = 0.003). New findings highlight that PVT1 acts as competing RNA to microRNAs to protect mRNAs from miRNAs repression. Therefore, we also discuss PVT1-related microRNAs and their interaction in tumourigenesis. In conclusion, PVT1 may be a potential biomarker of poor prognosis for patients with different cancer types.

Long non-coding RNA LINC01410 promotes colon cancer cell proliferation and invasion by inhibiting miR-3128

A previous study implied that long intergenic non-coding RNA 1410 (LINC01410) promotes angiogenesis and metastasis of gastric cancer. However, the role of LINC01410 in colon cancer (CC) has remained elusive. In the present study, LINC01410 was identified to be highly expressed in CC tissues compared to adjacent normal tissues. It was indicated that high expression of LINC01410 in CC tissues was associated with poor prognosis. Further functional study suggested that LINC01410 knockdown significantly reduced the proliferation and invasive capacity of HT-29 and SW620 cells, and inhibited the cell cycle. Regarding the mechanism, LINC01410 was indicated to serve as a sponge for microRNA (miR)-3128, as evidenced by a luciferase reporter assay. Furthermore, knockdown of LINC01410 significantly increased the levels of miR-3128. In addition, miR-3128 was markedly downregulated in CC tissues compared with that in adjacent normal tissues. A rescue assay revealed that inhibition of miR-3128 significantly abrogated the effects of LINC01410 knockdown on CC cell proliferation and invasion. In conclusion, the present study demonstrated that LINC01410 functions as an oncogene in CC, at least in part by directly inhibiting miR-3128.

SOX2 recruits KLF4 to regulate nasopharyngeal carcinoma proliferation via PI3K/AKT signaling

SOX2 is a transcription factor that contributes to transcription modification and cancer, but the mechanism by which SOX2 regulates nasopharyngeal carcinoma cell proliferation is not well understood. Here, we identify a SOX2 signaling pathway that facilitates nasopharyngeal carcinoma, where it is upregulated. SOX2 expression was associated with nasopharyngeal carcinoma patient survival. SOX2 knockdown inhibited cell proliferation, colony formation, and tumorigenesis in an subcutaneous mouse xenograft model system. Six hundred and ninety-nine candidate SOX2 downstream dysregulated genes were identified in nasopharyngeal carcinoma cells through cDNA microarray analysis. SOX2 recruited the nuclear transcription factor KLF4 to bind to the PIK3CA promoter upregulate PIK3CA expression, acting to enhance PI3K/AKT signaling and tumorigenesis by upregulating PIK3CA expression. Besides, overexpressing activated AKT or PIK3CA rescued the growth inhibition of cells due to SOX2 knockdown. Together, our study suggest that SOX2 exhibits oncogenic properties and may be a reliable molecular biomarker in nasopharyngeal carcinoma. Targeting SOX2 might be a promising treatment strategy for nasopharyngeal carcinoma treatment.

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.

The Impact of lncRNA Dysregulation on Clinicopathology and Survival of Breast Cancer: A Systematic Review and Meta-analysis

Dysregulation of multiple long non-coding RNAs (lncRNAs) was reported to play major roles in breast cancer (BC). Here we aimed to collect most of the relevant literature to assess the prognostic value of lncRNAs in BC. To this end, we systematically searched PubMed, Embase, Web of Science, Chinese National Knowledge Infrastructure (CNKI), and Wanfang to identify published articles on the associations of lncRNAs with clinicopathology and/or survival of BC. Via this searching, we identified 70 articles involving 9,307 BC patients and regarding 48 lncRNAs. The expression of 41 lncRNAs was related to one or more clinicopathological parameters of BC, including tumor size; lymph node metastasis; histological grade; TNM stage; and estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER-2) statuses (p < 0.05). Dysregulation of 28 lncRNAs was associated with overall survival, and abnormal expression of 9 lncRNAs was linked to disease-free survival. Furthermore, the expression level of 3 lncRNAs was correlated with metastasis-free survival, 3 lncRNAs with relapse-free survival, and 3 lncRNAs with progression-free survival. Our analysis showed that multiple lncRNAs were significantly associated with BC clinicopathology and survival. A large-scale study is needed to verify the prognostic value of these lncRNAs in BC.