Clinical significance of long intergenic noncoding RNA-p21 in colorectal cancer

Incense-burning smoke ingredient Auramine enhances lincRNA-p21 expression for chemosensitization in p53-mutated non-small cell lung cancer

Incense-burning smoke is a deleterious air pollutant that initiates cytotoxic effects by inducing apoptosis in lung epithelial cells and also acts as a risk factor for lung cancers. Auramine, an ingredient of incense smoke, has been implicated in tumor progression and cellular sensitivity in non-small cell lung cancer (NSCLC) towards anti-cancer agents through unclear mechanisms. Tumor protein p53 (TP53)-activated long intergenic non-coding RNA-p21 (lincRNA-p21) undertakes a pivotal role in regulating cell apoptosis and chemosensitivity. TP53 mutations prevalent in 50% of NSCLC, contribute to diminished therapeutic efficacy. However, the influence of auramine on chemotherapy-induced lincRNA-p21 expression and apoptosis in NSCLC with different TP53 genetic statuses remains unexplored. This study disclosed that both wild-type p53 (wtp53) and mutant p53 (mutp53) mediate lincRNA-p21 expression, albeit through distinct promoter enhancers, p53-response element (p53RE) and non-B DNA structure G-quadruplex (GQ), respectively. Intriguingly, auramine functions as an effective stabilizer of the GQ structure, augmenting mutp53-mediated lincRNA-p21 expression and enhancing apoptosis and cellular sensitivity to chemotherapy in mutp53-expressing NSCLC cells. These findings suggest a mechanism by which mutp53, in the presence of auramine, is endowed with tumor-suppressing function akin to wtp53, thereby aiding in combating chemoresistance in NSCLC cells harboring TP53 mutations.

Targeting long non-coding RNAs in cancer therapy using CRISPR-Cas9 technology: A novel paradigm for precision oncology

Cancer is the second leading cause of death worldwide, despite recent advances in its identification and management. To improve cancer patient diagnosis and care, it is necessary to identify new biomarkers and molecular targets. In recent years, long non-coding RNAs (lncRNAs) have surfaced as important contributors to various cellular activities, with growing proof indicating their substantial role in the genesis, development, and spread of cancer. Their unique expression profiles within specific tissues and their wide-ranging functionalities make lncRNAs excellent candidates for potential therapeutic intervention in cancer management. They are implicated in multiple hallmarks of cancer, such as uncontrolled proliferation, angiogenesis, and immune evasion. This review article explores the innovative application of CRISPR-Cas9 technology in targeting lncRNAs as a cancer therapeutic strategy. The CRISPR-Cas9 system has been widely applied in functional genomics, gene therapy, and cancer research, offering a versatile platform for lncRNA targeting. CRISPR-Cas9-mediated targeting of lncRNAs can be achieved through CRISPR interference, activation or the complete knockout of lncRNA loci. Combining CRISPR-Cas9 technology with high-throughput functional genomics makes it possible to identify lncRNAs critical for the survival of specific cancer subtypes, opening the door for tailored treatments and personalised cancer therapies. CRISPR-Cas9-mediated lncRNA targeting with other cutting-edge cancer therapies, such as immunotherapy and targeted molecular therapeutics can be used to overcome the drug resistance in cancer. The synergy of lncRNA research and CRISPR-Cas9 technology presents immense potential for individualized cancer treatment, offering renewed hope in the battle against this disease.

A cytosine-patch sequence motif identified in the conserved region of lincRNA-p21 interacts with the KH3 domain of hnRNPK

Long Intergenic Non-coding RNAs (lincRNAs) are the largest class of long non-coding RNAs in eukaryotes, originating from the genome's intergenic regions. A ∼4 ​kb long lincRNA-p21 is derived from a transcription unit next to the p21/Cdkn1a gene locus. LincRNA-p21 plays regulatory roles in p53-dependent transcriptional and translational repression through its physical association with proteins such as hnRNPK and HuR. It is also involved in the aberrant gene expression in different cancers. In this study, we have carried out a bioinformatics-based gene analysis and annotation of lincRNA-p21 to show that it is highly conserved in primates and identified two conserved domains in its sequence at the 5' and 3' terminal regions. hnRNPK has previously been shown to interact specifically with the 5' conserved region of lincRNA-p21. hnRNPK is known to bind preferentially to the pyrimidine-rich (poly C) nucleotide sequences in RNAs. Interestingly, we observed a single occurrence of a cytosine-rich patch (C-patch) consisting of a CUCCCGC sequence in the 5' conserved region of human lincRNA-p21, making it a putative hnRNPK binding motif. Using NMR and ITC experiments, we showed that the single-stranded C-patch containing RNA sequence motif interacts specifically with the KH3 domain of hnRNPK.

The Prediction of Necroptosis-Related lncRNAs in Prognosis and Anticancer Therapy of Colorectal Cancer

Background

Colorectal cancer is one of the most common gastrointestinal malignancies globally. Necroptosis has been proved to play a role in the occurrence and development of the tumor, which makes it a new target for molecular therapy. However, the role of necroptosis in colorectal cancer remains unknown yet. Our study aims to build a prognostic signature of necroptosis-related lncRNAs (nrlncRNAs) to predict the outcomes of patients with colorectal cancer and facilitate in anticancer therapy.

Method

We obtained RNA-seq and clinical data of colorectal adenocarcinoma from the TCGA database and got prognosis-related nrlncRNAs by univariate regression analysis. Then, we carried out the LASSO regression and multivariate regression analysis to build the prognostic signature, whose predictive ability was tested by the Kaplan-Meier as well as ROC curves and verified by the internal cohort. Moreover, we divided the cohort into 2 groups based on median of risk scores: high- and low-risk groups. By analyzing the difference in the tumor microenvironment, microsatellite instability, and tumor mutation burden between the two groups, we explored the potential chemotherapy and immunotherapy drugs.

Results

We screened out 9 nrlncRNAs and built a prognostic signature based on them. With its good prognostic ability, the risk scores can act as an independent prognostic factor for patients with colorectal cancer. The overall survival rate of patients in high-risk group was significantly higher than the low-risk one. Furthermore, risk scores can also give us hints about the tumor microenvironment and facilitate in predicting the response to the CTLA-4 blocker treatment and other chemotherapeutic agents with potential efficacy such as cisplatin and staurosporine.

Conclusions

In conclusion, our prognostic signature of necroptosis-related lncRNAs can facilitate in predicting the prognosis and response to the anticancer therapy of colorectal cancer patients.

The role of lincRNA-p21 in regulating the biology of cancer cells

Long non-coding RNAs (lncRNAs) are a type of multifunctional endogenous RNA transcript. The dysregulation of lncRNAs is considered to play a role in the initiation and progression of cancer. One such lncRNA, long intergenic non-coding RNA-p21 (lincRNA-p21), was identified in 2010 as a regulator in the p53 pathway and is gradually being identified to play crucial roles in diverse cellular processes. In this review, we have summarised the diverse regulatory functions of lincRNA-p21. For example, lincRNA-p21 has been reported to function as a protein decoy, act as a competitive endogenous RNA, regulate the transcription, regulate the translation processes and exist in the secreted exosomes. Furthermore, we highlight the emerging roles of lincRNA-p21 in cancer cell regulation. Various types of cancers, including colorectal carcinoma, hepatocellular carcinoma and non-small cell lung carcinoma, aberrantly express lincRNA-p21. However, the current understanding of the roles of lincRNA-p21 in cancer remains limited. Therefore, considering its potential as a valuable therapeutic target or biomarker for cancer, more research should be conducted to understand the role of lincRNA-p21 in cancer and other diseases.

LncRNA-p21 suppresses cell proliferation and induces apoptosis in gastric cancer by sponging miR-514b-3p and up-regulating ARHGEF9 expression

The long non-coding RNA p21 (lncRNA-p21) was a tumor suppressor gene in most cancer types including gastric cancer (GC). We aimed to identify a specific lncRNA-p21-involved pathway in regulating the proliferation and apoptosis of GC cells. A lower lncRNA-p21 expression in tumors was associated with advanced disease stage and predicted worse survival of GC patients. LncRNA-p21 overexpression in GC cell line somatic gastric cancer (SGC)-7901 and human gastric cancer (HGC)-27 suppressed cell proliferation and enhanced apoptosis, while lncRNA-p21 knockdown caused the opposite effects. Through bioinformatics analysis and luciferase-based reporter assays, we identified miR-514b-3p as a sponge target of lncRNA-p21. Cdc42 guanine nucleotide exchange factor 9 (ARHGEF9), functioned as a tumor suppress factor in GC, was found as the downstream target of miR-514-3p, and their expressions were negatively correlated in GC tumor tissues. In addition, like lncRNA-p21 overexpression alone, miR-514-3p inactivation alone also led to decreased proliferation and increased apoptosis in SGC-7901 and HGC-27 cells, which were markedly attenuated by additional ARHGEF9 knockdown. Xenograft SGC-7901 cells with more lncRNA-p21 or ARHGEF9 expressions or with less miR-514-3p expression exhibited obviously slower in vivo growth than the control SGC-7901 cells in nude mice. Our study reveals a novel lncRNA-p21/miR-514b-3p/ARHGEF9 pathway that can be targeted for GC therapy.

LINC01210 promotes malignant phenotypes of colorectal cancer through epigenetically upregulating SRSF3

Long non-coding RNAs (lncRNAs) have been linked to tumorigenesis. However, the role of LINC01210 in colorectal cancer (CRC) remains unclear. Relative levels of LINC01210 in CRC tissues and adjacent tissues were determined. Proliferative, migratory, and invasive abilities were examined in HCT116 cells and LoVo cells after silencing or overexpressing LINC01210. The interaction between LINC01210 and SRSF3 was explored by ChIP-PCR. Upregulated LINC01210 was associated with metastasis and advanced stage of CRC. Silencing LINC01210 attenuated proliferative, migratory, and invasive abilities in LoVo cells, while overexpressing LINC01210 promoted proliferative, migratory, and invasive abilities in HCT116 cells. Mechanism study revealed that LINC01210 increased the expression of SRSF3 by recruiting mixed lineage leukaemia protein-1, which upregulated the trimethylation of H3K4 me3 on SRSF3 promoter. Silencing SRSF3 reversed the effects of LINC01210 on CRC cells. In conclusions, LINC01210 accelerated proliferation and invasion in CRC cells through epigenetically upregulating SRSF3, and may be a potential therapeutic target for CRC treatment.

Long Noncoding RNA LOC550643 Acts as an Oncogene in the Growth Regulation of Colorectal Cancer Cells

Long noncoding RNAs play a key role in the progression of colorectal cancer (CRC). However, the role and mechanism of LOC550643 in CRC cell growth and metastasis remain largely unknown. In this study, we assessed the clinical impacts of LOC550643 on CRC through the analysis of The Cancer Genome Atlas database, which revealed the significant upregulation of LOC550643 in CRC. Moreover, the high expression of LOC550643 was associated with poor survival in patients with CRC (p = 0.001). Multivariate Cox regression analysis indicated that LOC550643 overexpression was an independent prognostic factor for shorter overall survival in patients with CRC (adjusted hazard ratio, 1.90; 95% confidence interval, 1.21-3.00; p = 0.006). A biological function analysis revealed that LOC550643 knockdown reduced colon cancer cell growth by hindering cell cycle progression. In addition, LOC550643 knockdown significantly induced cell apoptosis through the inhibition of signaling activity in phosphoinositide 3-kinases. Moreover, LOC550643 knockdown contributed to the inhibition of migration and invasion ability in colon cancer cells. Furthermore, miR-29b-2-5p interacted with the LOC550643 sequence. Ectopic miR-29b-2-5p significantly suppressed colon cancer cell growth and motility and induced cell apoptosis. Our findings suggest that, LOC550643-miR-29b-2-5p axis was determined to participate in the growth and metastasis of colon cancer cells; this could serve as a useful molecular biomarker for cancer diagnosis and as a potential therapeutic target for CRC.

Galloflavin Relieves the Malignant Behavior of Colorectal Cancer Cells in the Inflammatory Tumor Microenvironment

Background: In this study, we mainly aimed to explore the correlation between galloflavin and NLRP3 and its effect on colorectal cancer.

Methods: NLRP3 was overexpressed in SW480 cells; LPS + ATP was used to mimic the inflammatory microenvironment. Wound healing assay and Transwell assay were utilized to detect cell migration and invasion abilities; CCK-8 assay was performed to detect cell viability alterations; colony formation assay was conducted to detect colony formation ability; Western blot was used to detect the levels of NLRP3, ASC, C-Myc, and P21. SW480 cells were pretreated with high-dose and low-dose galloflavin, followed by observation of their effects on cell metastasis and invasion. NLRP3 was knocked out in SW480 to construct the SW480-NLRP3^−/− cell line, followed by high-dose galloflavin treatment and subsequent observation of cell metastasis and invasion abilities. Small molecule–protein docking and pull-down assay were performed to confirm the targeting relationship between galloflavin and NLRP3. After constructing a tumor-bearing mice model, galloflavin was intragastrically administered, followed by detection of tumor growth, expression of NLRP3 and ASC by immunohistochemistry, and tumor histopathology by H&E staining.

Results: After NLRP3 overexpression and LPS/ATP induction in SW480, the cell migration and invasion abilities were significantly enhanced, and cell viability was also enhanced. The activation of NLRP3 could promote the malignant behavior of colorectal cancer cells in the inflammatory microenvironment. Galloflavin treatment could significantly attenuate the malignant behavior of SW480 in the inflammatory microenvironment and inhibit the migration and invasion capabilities of SW480. The knockout of NLRP3 inhibited the effect of galloflavin, which did not significantly change the migration and invasion abilities. Molecular docking and pull-down assay revealed a targeted binding relationship between galloflavin and NLRP3 and that galloflavin is bound to NLRP3 not ASC protein. Moreover, galloflavin could inhibit tumor growth and decrease the expression of NLRP in tumor-bearing mice.

Conclusion: In this study, we found that NLRP3 could promote the migration and invasion of colorectal cancer cells in the inflammatory microenvironment. Galloflavin could inhibit the malignant behavior of colorectal cancer cells by targeting NLRP3.

ERα determines the chemo-resistant function of mutant p53 involving the switch between lincRNA-p21 and DDB2 expressions

Mutant p53 (mutp53) commonly loses its DNA binding affinity to p53 response elements (p53REs) and fails to induce apoptosis fully. However, the p53 mutation does not predict chemoresistance in all subtypes of breast cancers, and the critical determinants remain to be identified. In this study, mutp53 was found to mediate chemotherapy-induced long intergenic noncoding RNA-p21 (lincRNA-p21) expression by targeting the G-quadruplex structure rather than the p53RE on its promoter to promote chemosensitivity. However, estrogen receptor alpha (ERα) suppressed mutp53-mediated lincRNA-p21 expression by hijacking mutp53 to upregulate damaged DNA binding protein 2 (DDB2) transcription for subsequent DNA repair and chemoresistance. Levels of lincRNA-p21 positively correlated with the clinical responses of breast cancer patients to neoadjuvant chemotherapy and had an inverse correlation with the ER status and DDB2 level. In contrast, the carboplatin-induced DDB2 expression was higher in ER-positive breast tumor tissues. These results demonstrated that ER status determines the oncogenic function of mutp53 in chemoresistance by switching its target gene preference from lincRNA-p21 to DDB2 and suggest that induction of lincRNA-p21 and targeting DDB2 would be effective strategies to increase the chemosensitivity of mutp53 breast cancer patients.

Expression of long non-coding RNA H19 in colorectal cancer patients with type 2 diabetes

The aim of this study was to explore the lncRNAs expression in colorectal cancer (CRC) patients with type 2 diabetes (T2DM) and evaluate the diagnostic value of lncRNAs expression in CRC patients with T2DM. The present study was conducted on two cohorts with CRC patients. The tissues levels of lncRNAs were measured by real-time PCR analysis. The results showed that H19 and MALAT1 expression were higher in CRC tissues than in normal colorectal mucosa (p = 1.59 × 10^-6 and p = 6.95 × 10^-9, respectively), whereas lincRNA-p21 showed lower expression in CRC tissues (p = 1.10 × 10^-4). Logistic regression analysis results indicated that the expression of H19 was significantly lower in CRC patients with T2DM compared with CRC patients without T2DM (p = .032). H19 expression in CRC group without T2DM was significantly associated with hypertension (p = .040). Additionally, the area under the receiver operating characteristic curve of H19 was 0.672 of the group CRC with T2DM, which suggests that H19 could be a useful biomarker and predictive targets for diagnosis of T2DM in CRC patients.

Lincp21-RNA as Predictive Response Marker for Preoperative Chemoradiotherapy in Rectal Cancer

Preoperative chemoradiotherapy (CRT) is a standard treatment for locally advanced rectal cancer (RC) patients, but its use in non-responders can be associated with increased toxicities and resection delay. LincRNA-p21 is a long non-coding RNA involved in the p53 pathway and angiogenesis regulation. We aimed to study whether lincRNA-p21 expression levels can act as a predictive biomarker for neoadjuvant CRT response. We analyzed RNAs from pretreatment biopsies from 70 RC patients treated with preoperative CRT. Pathological response was classified according to the tumor regression grade (TRG) Dworak classification. LincRNA-p21 expression was determined by RTqPCR. The results showed that lincRNA-p21 was upregulated in stage III tumors (p = 0.007) and in tumors with the worst response regarding TRG (p = 0.027) and downstaging (p = 0.016). ROC curve analysis showed that lincRNA-p21 expression had the capacity to distinguish a complete response from others (AUC:0.696; p = 0.014). LincRNA-p21 was shown as an independent marker of preoperative CRT response (p = 0.047) and for time to relapse (TTR) (p = 0.048). In conclusion, lincRNA-p21 is a marker of advanced disease, worse response to neoadjuvant CRT, and shorter TTR in locally advanced RC patients. The study of lincRNA-p21 may be of value in the individualization of pre-operative CRT in RC.

Cancer Susceptibility Candidate 9 (CASC9) Promotes Colorectal Cancer Carcinogenesis via mTOR-Dependent Autophagy and Epithelial-Mesenchymal Transition Pathways

BACKGROUND

Colorectal cancer (CRC) is the third most common cancer worldwide. Many recent studies have demonstrated that different long non-coding RNAs (lncRNAs) are involved in the initiation, advancement, and metastasis of many cancers including CRC. Cancer susceptibility candidate 9 (CASC9) is an lncRNA that has been reported in many cancers, but its role in CRC is poorly understood. In this study, we aimed to examine the expression of CASC9 in CRC cell lines and to determine the mechanism of action of CASC9 in CRC carcinogenesis.

METHODS

The expression of CASC9 in CRC tissues was compared with normal samples from publicly available datasets in The Cancer Genome Atlas (TCGA) and The Encyclopedia of RNA Interactomes (ENCORI). CASC9 expression was further verified in four CRC cell lines (DLD1, HT-29, SW480, and HCT-116) and normal colorectal cell line (CCD-112CoN) by real-time quantitative polymerase chain reaction (RT-qPCR). After gene silencing in HCT-116 and SW480, Cell Counting Kit-8 assay, clonogenic assay, and wound healing assay were performed to evaluate cell proliferation, viability, and migration index of cells. Western blotting was used to explore the key pathways involved.

RESULTS

CASC9 was significantly upregulated as analyzed from both public datasets TCGA and ENCORI where its overexpression was associated with poor survival of CRC patients. Similarly, CASC9 was significantly overexpressed in the CRC cell lines compared with normal cells studied. The silencing of CASC9 in HCT-116 and SW480 attenuated cell proliferation and migration significantly. Furthermore, pathways investigations showed that silencing of CASC9 significantly induced autophagy, promoted AMP-activated protein kinase (AMPK) phosphorylation, inhibited mTOR and AKT signaling pathways, and altered epithelial-mesenchymal transition (EMT) marker protein expression.

CONCLUSION

We demonstrated that silencing of CASC9 contributes to the reduced CRC cell proliferation and migration by regulating autophagy and AKT/mTOR/EMT signaling. Therefore, CASC9 plays an important role in carcinogenesis, and its expression may act as a prognostic biomarker and a potential therapeutic target of CRC management.

P53 long noncoding RNA regulatory network in cancer development

The protein p53 as a transcription factor with strong tumor-suppressive activities is known to trigger apoptosis via multiple pathways and is directly involved in the recognition of DNA damage and DNA repair processes. P53 alteration is now recognized as a common event in the pathogenesis of many types of human malignancies. Deregulation of tumor suppressor p53 pathways plays an important role in the activation of cell proliferation or inactivation of apoptotic cell death during carcinogenesis and tumor progression. Mounting evidence indicates that the p53 status of tumors and also the regulatory functions of p53 may be relevant to the long noncoding RNAs (lncRNA)-dependent gene regulation programs. Besides coding genes, lncRNAs that do not encode for proteins are induced or suppressed by p53 transcriptional response and thus control cancer progression. LncRNAs also have emerged as key regulators that impinge on the p53 signaling network orchestrating global gene-expression profile. Studies have suggested that aberrant expression of lncRNAs as a molecular-genomic signature may play important roles in cancer biology. Accordingly, it is important to elucidate the mechanisms by which the crosstalk between lncRNAs and p53 occurs in the development of numerous cancers. Here, we review how several classes of lncRNAs and p53 pathways are linked together in controlling the cell cycle and apoptosis in various cancer cells in both human and mouse model systems.

Long Non-Coding RNAs: Role in Testicular Cancers

In the last few years lncRNAs have gained increasing attention among the scientific community, thanks to the discovery of their implication in many physio-pathological processes. In particular, their contribution to tumor initiation, progression, and response to treatment has attracted the interest of experts in the oncologic field for their potential clinical application. Testicular cancer is one of the tumors in which lncRNAs role is emerging. Said malignancies already have very effective treatments, which although lead to the development of quite serious treatment-related conditions, such as secondary tumors, infertility, and cardiovascular diseases. It is therefore important to study the impact of lncRNAs in the tumorigenesis of testicular cancer in order to learn how to exploit them in a clinical setting and to substitute more toxic treatments. Eventually, the use of lncRNAs as biomarkers, drug targets, or therapeutics for testicular cancer may represent a valid alternative to that of conventional tools, leading to a better management of this malignancy and its related conditions, and possibly even to the treatment of poor prognosis cases.

Long Noncoding RNAs at the Crossroads of Cell Cycle and Genome Integrity

The cell cycle is controlled by guardian proteins that coordinate the process of cell growth and cell division. Alterations in these processes lead to genome instability, which has a causal link to many human diseases. Beyond their well-characterized role of influencing protein-coding genes, an increasing body of evidence has revealed that long noncoding RNAs (lncRNAs) actively participate in regulation of the cell cycle and safeguarding of genome integrity. LncRNAs are versatile molecules that act via a wide array of mechanisms. In this review, we discuss how lncRNAs are implicated in control of the cell cycle and maintenance of genome stability and how changes in lncRNA-regulatory networks lead to proliferative diseases such as cancer.

The Role, Function, and Mechanism of Long Intergenic Noncoding RNA1184 (linc01184) in Colorectal Cancer

Background

Long intergenic noncoding RNA1184 (linc01184) has been recently discovered; however, its role in human diseases is limited to date. The present study is aimed at investigating the expression pattern and mechanism of linc01184 in colorectal cancer (CRC) tumorigenesis.

Methods

The expression of linc01184 in CRC tissues and cell lines was compared with that in normal controls. The functions of linc01184 in CRC cells were identified by overexpression and small interfering RNA (siRNA) approaches in vitro. Meanwhile, the target gene prediction software, luciferase reporter, RNA pull-down, and western blotting assays were used to analyze the oncogenic mechanism.

Results

We found that linc01184 was obviously upregulated in CRC tissues and cells when compared to normal controls, and its upregulation had a positive association with the CRC progression. linc01184 knockdown significantly suppressed CRC cell proliferation and invasion and promoted apoptosis. Besides, linc01184 acted as a competitive endogenous RNA (ceRNA) by directly binding to microRNA-331 (miR-331), and its overexpression resulted in notable increases of human epidermal growth factor receptor 2 (HER2), phosphorylated Ser/Thr kinases (p-Akt), and extracellular regulated protein kinase 1/2 (p-ERK1/2) at posttranscriptional levels in CRC cells, which were antagonized by miR-331.

Conclusions

The findings reveal for the first time that linc01184 is an enhancer for the proliferation and invasion of CRC by functioning as a ceRNA through the linc01184-miR-331-HER2-p-Akt/ERK1/2 pathway regulatory network.

The Functions and Unique Features of LncRNAs in Cancer Development and Tumorigenesis

Over the past decades, research on cancer biology has focused on the involvement of protein-coding genes in cancer development. Long noncoding RNAs (lncRNAs), which are transcripts longer than 200 nucleotides that lack protein-coding potential, are an important class of RNA molecules that are involved in a variety of biological functions. Although the functions of a majority of lncRNAs have yet to be clarified, some lncRNAs have been shown to be associated with human diseases such as cancer. LncRNAs have been shown to contribute to many important cancer phenotypes through their interactions with other cellular macromolecules including DNA, protein and RNA. Here we describe the literature regarding the biogenesis and features of lncRNAs. We also present an overview of the current knowledge regarding the roles of lncRNAs in cancer from the view of various aspects of cellular homeostasis, including proliferation, survival, migration and genomic stability. Furthermore, we discuss the methodologies used to identify the function of lncRNAs in cancer development and tumorigenesis. Better understanding of the molecular mechanisms involving lncRNA functions in cancer is critical for the development of diagnostic and therapeutic strategies against tumorigenesis.

Non-coding RNAs and potential therapeutic targeting in cancer

Recent advances have begun to clarify the physiological and pathological roles of non-coding RNAs (ncRNAs) in various diseases, including cancer. Among these, microRNAs (miRNAs) have been the most studied and have emerged as key players that are involved in the regulation of important growth regulatory pathways in cancer pathogenesis. The ability of a single ncRNA to modulate the expression of multiple downstream gene targets and associated pathways, have provided a rationale to pursue them for therapeutic drug development in cancer. In this context, early data from pre-clinical studies have demonstrated that synthetic miRNA-based therapeutic molecules, along with various protective coating approaches, has allowed for their efficient delivery and anti-tumor activity. In fact, some of the miRNA-based cancer therapeutic strategies have shown promising results even in early-phase human clinical trials. While the enthusiasm for ncRNA-based cancer therapeutics continue to evolve, the field is still in the midst of unraveling a more precise understanding of the molecular mechanisms and specific downstream therapeutic targets of other lesser studied ncRNAs such as the long-non-coding RNAs, transfer RNAs, circular RNAs, small nucleolar RNAs, and piwi-interacting RNAs. This review article provides the current state of knowledge and the evolving principles for ncRNA-based therapeutic approaches in cancer, and specifically highlights the importance of data to date and the approaches that are being developed to overcome the challenges associated with their delivery and mitigating the off-target effects in human cancers.

LncRNAs in Cancer: From garbage to Junk

Sequencing-based transcriptomics has significantly redefined the concept of genome complexity, leading to the identification of thousands of lncRNA genes identification of thousands of lncRNA genes whose products possess transcriptional and/or post-transcriptional regulatory functions that help to shape cell functionality and fate. Indeed, it is well-established now that lncRNAs play a key role in the regulation of gene expression through epigenetic and posttranscriptional mechanims. The rapid increase of studies reporting lncRNAs alteration in cancers has also highlighted their relevance for tumorigenesis. Herein we describe the most prominent examples of well-established lncRNAs having oncogenic and/or tumor suppressive activity. We also discuss how technical advances have provided new therapeutic strategies based on their targeting, and also report the challenges towards their use in the clinical settings.

The Long Noncoding RNA LOC441461 (STX17-AS1) Modulates Colorectal Cancer Cell Growth and Motility

Simple Summary

Long noncoding RNA dysfunction is crucial for colorectal carcinoma (CRC) development. Whether the dysfunction of LOC441461, a novel lncRNA, can regulate cancer-related signaling pathways in cancer progression remains unclear. Here, we uncover the oncogenic role of LOC441461 in colon cancer cell growth and motility and identify a novel mechanism for LOC441461 knockdown-induced suppression of cancer motility through modulating Ras homolog family member A (RhoA)/Rho-associated protein kinase (ROCK) activity. This is the first report that LOC441461 knockdown impairs cell cycle progression and accelerates the apoptosis of colon cancer cells following chemotherapy drug treatment. The results suggest that LOC441461 expression confers drug sensitivity in colon cancer by inducing apoptosis. Our findings offer new insight into LOC441461 regulation and provide an application for colon cancer therapy in the future.

Abstract

Colorectal carcinoma (CRC) is one of the most prevalent cancers worldwide and has a high mortality rate. Long noncoding RNAs (lncRNAs) have been noted to play critical roles in cell growth; cell apoptosis; and metastasis in CRC. This study determined that LOC441461 expression was significantly higher in CRC tissues than in adjacent normal mucosa. Pathway enrichment analysis of LOC441461-coexpressed genes revealed that LOC441461 was involved in biological functions related to cancer cell growth and motility. Knockdown of the LOC441461 expression significantly suppressed colon cancer cell growth by impairing cell cycle progression and inducing cell apoptosis. Furthermore, significantly higher LOC441461 expression was discovered in primary colon tumors and metastatic liver tumors than in the corresponding normal mucosa, and LOC441461 knockdown was noted to suppress colon cancer cell motility. Knockdown of LOC441461 expression suppressed the phosphorylation of MLC and LIMK1 through the inhibition of RhoA/ROCK signaling. Overall, LOC441461 was discovered to play an oncogenic role in CRC cell growth and motility through RhoA/ROCK signaling. Our findings provide new insights into the regulation of lncRNAs and their application in the treatment of colon cancer

LincRNA-p21 Levels Relates to Survival and Post-Operative Radiotherapy Benefit in Rectal Cancer Patients

LincRNA-p21 is a long non-coding RNA involved in the p53 pathway and angiogenesis regulation that acts as prognostic marker in several tumors. In the present study, we aimed to analyze the clinical value of lincRNA-p21 in 177 resected stage I–III colorectal cancer (CRC) patients. Tumor and normal paired tissue and plasma samples from tumor-draining mesenteric veins and paired peripheral veins were analyzed. LincRNA-p21 expression was determined by RTqPCR and correlated with disease-free (DFS) and overall survival (OS). LincRNA-p21 was downregulated in tumor versus normal tissue (p = 0.0012). CRC patients with high lincRNA-p21 expression had shorter DFS (p = 0.0372) and shorter OS (p = 0.0465). Of note, the major prognostic impact was observed in the subset of rectal cancer patients where patients with high lincRNA-p21 levels had worse DFS (p = 0.0226) and OS (p = 0.0457). Interestingly, rectal cancer patients with high lincRNA-p21 benefited from post-operative chemoradiotherapy, as indicated by a longer OS in the group of high lincRNA-p21 patients receiving post-operative chemoradiotherapy (p = 0.04). Finally, patients with high lincRNA-p21 levels in mesenteric vein (MV) had shorter OS (p = 0.0329). LincRNA-p21 is a marker of advanced disease and worse outcome in CRC. Moreover, rectal cancer patients with high lincRNA-p21 levels could benefit from post-operative chemoradiotherapy, and plasmatic-lincRNA-p21 is a promising liquid biopsy biomarker.

Non-coding RNAs, metabolic stress and adaptive mechanisms in cancer

Metabolic reprogramming in cancer describes the multifaceted alterations in metabolism that contribute to tumorigenesis. Major determinants of metabolic phenotypes are the changes in signalling pathways associated with oncogenic activation together with cues from the tumor microenvironment. Therein, depleted oxygen and nutrient levels elicit metabolic stress, requiring cancer cells to engage adaptive mechanisms. Non-coding RNAs (ncRNAs) act as regulatory elements within metabolic pathways and their widespread dysregulation in cancer contributes to altered metabolic phenotypes. Indeed, ncRNAs are the regulatory accomplices of many prominent effectors of metabolic reprogramming including c-MYC and HIFs that are activated by metabolic stress. By example, this review illustrates the range of ncRNAs mechanisms impacting these effectors throughout their DNA-RNA-protein lifecycle along with presenting the mechanistic roles of ncRNAs in adaptive responses to glucose, glutamine and lipid deprivation. We also discuss the facultative activation of metabolic enzymes by ncRNAs, a phenomenon which may reflect a broad but currently invisible level of metabolic regulation. Finally, the translational challenges associated with ncRNA discoveries are discussed, emphasizing the gaps in knowledge together with importance of understanding the molecular basis of ncRNA regulatory mechanisms.

MicroRNA‑383‑5p inhibits the proliferation and promotes the apoptosis of gastric cancer cells by targeting cancerous inhibitor of PP2A

The aberrant expression of microRNA (miRNAor miR)‑383‑5p has been found in numerous types of cancer. However, the function of miR‑383‑5p in gastric cancer (GC) remains elusive and requires further investigation. In the present study, the level of miR‑383‑5p and cancerous inhibitor of PP2A (CIP2A) in GC cell lines was determined by reverse transcription‑quantitative PCR analysis. GC cell proliferation, apoptosis and cell cycle distribution were determined by the MTT assay and flow cytometry, respectively. The mRNA target of miR‑383‑5p was identified by dual luciferase activity assay. It was observed that the expression of miR‑383‑5p was lower and that of CIP2A was higher in GC cells compared with the GES‑1 normal human gastric epithelial cell line. Transfectoin with miR‑383‑5p mimic significantly inhibited GC cell proliferation, while it promoted cell apoptosis and G0/G1 arrest by targeting CIP2A. Taken together, the findings of the present study demonstrate that miR‑383‑5p inhibits GC cell proliferation and promotes apoptosis and G0/G1 arrest by targeting CIP2A, indicating that targeting miR‑383‑5p may hold promise as a future therapeutic strategy for patients with GC.

An update on long intergenic noncoding RNA p21: a regulatory molecule with various significant functions in cancer

Long intergenic noncoding RNA p21 was mapped on the human chromosome 6p21.2. Accordingly, it was firstly described by promoting the p53-dependent apoptosis in the mouse. Also, it is a new lncRNA playing some vital roles in the cell cycle, apoptosis, cell proliferation, tumorigenesis, invasion, metastasis, and angiogenesis. In this regard, it was shown that, lincRNA-p21 regulates these biological processes involved in carcinogenesis through various signaling pathways including Notch signaling, JAK2/STAT3, and AKT/mTOR pathways. Another mechanism by that lincRNA-p21 can affect these processes is a cross-talk with different miRNAs. In vitro and in vivo studies revealed dysregulation of lincRNA-p21 in various human cancers. In addition, emerging evidence demonstrated that, lincRNA-p21 can be considered as a potential prognostic and therapeutic biomarker in cancers. Also, lincRNA-p21 enhances the response to radiotherapy for colorectal cancer. However, the molecular mechanisms of lincRNA-p21 in carcinogenesis have not been fully elucidated so far. So, this review summarizes the function of lincRNA-p21, as a tumor suppressor factor in different biological processes implicated in cancers.

Long intergenic non-coding RNA-p21 is associated with poor prognosis in chronic lymphocytic leukemia

BACKGROUND

Long non-coding RNAs (LncRNAs) are RNA transcripts longer than 200 nucleotides. They are new players in transcriptional regulation and cancer research. LincRNA-p21 is a p53-regulated lncRNA involved in the p53 transcriptional network. It has an important role in regulating cellular proliferation and apoptosis. Chronic lymphocytic leukemia is derived by a typical defect in apoptosis and characterized by clonal proliferation and accumulation of mature B cells. The aim of the present study was to assess the expression pattern of the lincRNA-p21 and investigate its potential role as a new prognostic marker in CLL.

METHODS

The study was conducted on 80 newly diagnosed CLL patients and 80 age- and sex-matched controls. The analysis of LincRNA-p21 and the p53 downstream proapoptotic target genes (MDM2, PUMA, BAX, and NOXA) was performed by real-time PCR. The cytogenetic abrasions and expression of ZAP70 and CD38 were detected by FISH and Flow cytometry, respectively.

RESULTS

LincRNA-p21 was significantly downregulated in CLL patients compared to controls. The downstream proapoptotic targets were significantly downregulated in CLL patients and positively correlated with lincRNA-p21. Low expression of lincRNA-p21 was associated with poor prognostic markers (advanced stages of CLL, del 17p13, ZAP70, and CD38 expression), failure of complete remission, shorter progression free survival, and overall survival. Low lincRNA-p21 expression was independently prognostic for shorter time to treatment.

CONCLUSION

Low expression of lincRNA-p21 demarcates a more aggressive form of CLL with poor prognosis. Therefore, it could be considered as a new prognostic marker to predict disease outcome in CLL.

Emerging Roles of lncRNAs in the Formation and Progression of Colorectal Cancer

Colorectal cancer (CRC) is the primary cause of cancer-related death worldwide; however, specific and sensitive tools for the early diagnosis and targeted therapy of CRC are currently lacking. High-throughput sequencing technology revealed that gene expression of long-chain non-coding RNAs (lncRNAs) in a number of cancers directly or indirectly interferes with various biological processes. Emerging evidence suggests that lncRNAs regulate target genes and play an important role in the biological processes of malignancies, including CRC. Many carcinostatic/oncogenic lncRNAs have been identified as biomarkers for metastasis and prognosis in CRC; hence, they serve as therapeutic tools. In this article, we systematically review the literature on the disordered lncRNAs in CRC from four aspects: DNA transcription, RNA level regulation, post-translational level, and the translation of lncRNAs into polypeptides. Subsequently, we analyze the mechanism through which lncRNAs participate in the biological process of CRC. Finally, we discuss the application and prospects of these lncRNAs in CRC.

Transcriptional profiling of long-intergenic noncoding RNAs in lung squamous cell carcinoma and its value in diagnosis and prognosis

Background

Long intergenic noncoding RNAs (lincRNAs) are a series of novel transcribed regions expressed in cancers that may represent candidate biomarkers for lung squamous cell carcinoma (LSqCC) treatment. In this study, we evaluated the lincRNA profile in LSqCC patients and screened valuable lincRNAs for diagnosis and prognosis.

Methods

Transcriptome profiling of 549 samples derived from 501 LSqCC patients were identified in TCGA database. 48 patients had paired primary tumor (PT) and solid normal (SN) tissue samples, while 453 patients had only PT samples. 1,771 lincRNA candidates were evaluated. Paired test (Wilcoxon two‐sample paired signed rank tests) was performed in paired PT and SN samples. Logistic regression analysis were performed in independent 453 PT samples and 48 SN samples to screen the significant lincRNAs candidates for malignances. Independent 501 PT samples were further used to screen the significant lincRNAs candidates for prognosis.

Results

Among 1,771 lincRNAs, 10 lincRNAs were significant highly‐expressed risk candidates in PT samples, and 10 protective lincRNAs candidates were significant lowly‐expressed in PT samples. Among 10 highly‐expressed risk lincRNAs, a small panel of LINC00487, LINC01927, and C10orf143 (LINC00959) could effectively predict malignancies in paired samples (AUC = 0.7274, 95%CI = (0.6264, 0.8285)). When combined with protective lincRNA candidates LINC02315, LINC00491, and LINC01697, the predictive efficiency was greatly improved in both paired samples (AUC = 0.8030, 95%CI = (0.7250, 0.8810)) and independent samples (AUC = 0.7481, 95%CI= (0.6642, 0.8320)). Additionally, three highly‐expressed risk lincRNAs, LINC01031, LINC01088, and LINC01931, were significantly associated with poor prognosis in PT samples, suggesting potential targets for anti‐LSqCC treatment.

Conclusion

Therefore, lincRNAs could be promising biomarkers for predicting malignancies and potential anti‐LSqCC targets for drug development.

Diagnostic and prognostic potential of tissue and circulating long non-coding RNAs in colorectal tumors

Long non-coding RNAs (lncRNAs) are members of the non-protein coding RNA family longer than 200 nucleotides. They participate in the regulation of gene and protein expression influencing apoptosis, cell proliferation and immune responses, thereby playing a critical role in the development and progression of various cancers, including colorectal cancer (CRC). As CRC is one of the most frequently diagnosed malignancies worldwide with high mortality, its screening and early detection are crucial, so the identification of disease-specific biomarkers is necessary. LncRNAs are promising candidates as they are involved in carcinogenesis, and certain lncRNAs (e.g., CCAT1, CRNDE, CRCAL1-4) show altered expression in adenomas, making them potential early diagnostic markers. In addition to being useful as tissue-specific markers, analysis of circulating lncRNAs (e.g., CCAT1, CCAT2, BLACAT1, CRNDE, NEAT1, UCA1) in peripheral blood offers the possibility to establish minimally invasive, liquid biopsy-based diagnostic tests. This review article aims to describe the origin, structure, and functions of lncRNAs and to discuss their contribution to CRC development. Moreover, our purpose is to summarise lncRNAs showing altered expression levels during tumor formation in both colon tissue and plasma/serum samples and to demonstrate their clinical implications as diagnostic or prognostic biomarkers for CRC.

LincRNA-p21 leads to G1 arrest by p53 pathway in esophageal squamous cell carcinoma

Background: Esophageal squamous cell carcinoma (ESCC) is the fourth most common cause of cancer death in China. Long noncoding RNAs have emerged as critical regulators in cancer. Long intergenic noncoding RNA-p21, a kind of Long noncoding RNAs, LincRNA-p21 have been discussed dysregulated in several cancers, but its role in ESCC remains unknown. This study investigated the role of LincRNA-p21 in ESCC.

Materials and methods: The LincRNA-p21 expression level and its association with esophageal cancer was determined in 64 tumor tissues of esophageal squamous cell carcinoma patients and cells using quantitative real-time reverse transcription PCR. Fluorescence in situ hybridization of single-RNA molecular probes was used to determine subcellular localization of LincRNA-p21. CCK8 and EdU assays were used for proliferation assay, flow cytometry was performed for apoptosis and cell-cycle distribution, and 24-well Mill cell chamber was made for measuring the abilities of migration and invasion after transfected with lentivirus-expressing LincRNA-p21 in EC109 cells. Then, quantitative real-time reverse transcription PCR and Western blot detected the expression of p21. Further, UC2288, an inhibitor of p21, was used to decrease the level of p21, and flow cytometry was used to detect cell cycle. Finally, screening for differential pathways from microarray analysis and expression of p53 and cyclin D were detected by Western blot.

Results:LincRNA-p21 expression level was remarkably lower in tumor tissues versus nontumor tissues and lower in EC109 cells versus Het-1A cells. Statistical analysis found that LincRNA-p21 might enhance the risk of ESCC. We observed that LincRNA-p21 was expressed both in the nucleus and cytoplasm, and a larger proportion of LincRNA-p21 was observed in the cytoplasm. The results demonstrated that upregulating the expression of LincRNA-p21 could inhibit cell proliferation, migration, invasion, and the transition of cell cycle from G1 and promoted apoptosis of EC109. Then, we found that LincRNA-p21 promotes the expression of p21. Decreasing the level of p21 revealed that cell-cycle arrest was restored. Pathway analysis found p53 pathway was downregulated, and upregulation of LincRNA-p21 inhibited the expression of cyclin D.

Conclusion: Our study suggests that LincRNA-p21 plays as a tumor inhibitor in ESCC development and LincRNA-p21 might induce G1 arrest through p53 signal pathway.

The Long Noncoding RNA, LINC01555, Promotes Invasion and Metastasis of Colorectal Cancer by Activating the Neuropeptide, Neuromedin U

Background

This study aimed to investigate the role of the long noncoding RNA (lncRNA), LINC01555, on the migration and invasion of colorectal cancer (CRC) cells, its expression in CRC tissue, and its interaction with the neuropeptide, neuromedin U (NmU).

Material/Methods

LINC01555 expression in SW620 and HCT116 CRC cells, and NCM460 normal colorectal cells, and 48 resection specimens containing CRC and adjacent normal tissue, was detected by quantitative real-time polymerase chain reaction (qRT-PCR). Cox regression analysis was used to assess the relationship between LINC01555 expression and patient survival. The effects of LINC01555 expression on CRC cell proliferation, migration, and invasion were assessed using the cell counting kit-8 (CCK-8) assay, the colony formation assay, and the transwell assay. Functional studies determined the interaction between LINC01555 and NmU in the development of CRC.

Results

The Cancer Genome Atlas (TCGA) dataset showed that LINC01555 was highly expressed in CRC tissue when compared with adjacent normal colorectal tissue. LINC01555 expression was positively correlated with tumor stage, but negatively correlated with disease-free survival (DFS) and overall survival (OS) and was an independent risk factor for CRC. The receiver operating characteristic (ROC) curve analysis showed the diagnostic specificity of LINC01555 in CRC. Knockdown of LINC01555 inhibited cell proliferation, migration, and invasion of CRC cells. Functional studies showed that knockdown of NmU reduced cell migration and invasion of CRC cells that overexpressed LINC01555.

Conclusions

Increased expression of LINC01555 was found in CRC tissues and promoted the invasion of CRC cells by upregulating the expression of NmU.

Effect of lincRNA-p21 targeting HIF-1α on biological functions of liver cancer cells

The effects of long intergenic non-coding ribonucleic acid (lincRNA)-p21 targeting hypoxia-inducible factor-1α (HIF-1α) on proliferation, apoptosis and migration of liver cancer cells were investigated. MHCC97H liver cancer cells were infected with control lentivirus (control group) and lincRNA-p21 lentivirus (observation group), and control stable cell lines and lincRNA-p21 stable cell lines were screened and obtained by using puromycin. The expression levels of lincRNA-p21 messenger RNA (mRNA) in the control and observation groups were analyzed via reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Bioinformatics was used to search for the lincRNA-p21 target. The expression of target gene was analyzed via western blotting, and the proliferation, apoptosis, migration and in vivo tumor formation of MHCC97H cells in the control and observation groups were also analyzed. Compared with that in control group, the lincRNA-p21 mRNA level in observation group was increased significantly (P<0.05). It was found via bioinformatic comparison that HIF-1α was one of the targets of lincRNA-p21. Results of Western blotting revealed that the expression level of HIF-1α protein in cells in observation group was significantly downregulated (P<0.05). Besides, the level of vascular endothelial growth factor (VEGF) protein in cells in control group was obviously higher than that in observation group (P<0.05). Compared with those in control group, the cell proliferation and migration capacities in observation group were markedly reduced, but the apoptosis level was significantly increased (P<0.05). According to the in vivo tumor formation assay, the cell proliferation rate in control group was obviously higher than that in observation group (P<0.05). The number of tumor blood vessels in cells in control group was obviously reduced compared with that in observation group (P<0.05). lincRNA-p21 can significantly downregulate the level of HIF-1α, thus downregulating the expression of VEGF and affecting the cell proliferation, apoptosis and migration.

p53-targeted lincRNA-p21 acts as a tumor suppressor by inhibiting JAK2/STAT3 signaling pathways in head and neck squamous cell carcinoma

Background

Long intergenic noncoding RNA p21 (lincRNA-p21) is considered a target of wild-type p53, but little is known about its regulation by mutant p53 and its functions during the progression of head and neck squamous cell carcinoma (HNSCC).

Methods

RNAscope was used to detect the expression and distribution of lincRNA-p21. Chromatin immunoprecipitation and electrophoretic mobility shift assays were performed to analyze the transcriptional regulation of lincRNA-p21 in HNSCC cells. The biological functions of lincRNA-p21 were investigated in vitro and in vivo. RNA immunoprecipitation and pull-down assays were used to detect the direct binding of lincRNA-p21.

Results

Lower lincRNA-p21 expression was observed in HNSCC tissues and indicated worse prognosis. Both wild and mutant type p53 transcriptionally regulated lincRNA-p21, but nuclear transcription factor Y subunit alpha (NF-YA) was essential for mutant p53 in the regulation of lincRNA-p21. Ectopic expression of lincRNA-p21 significantly inhibited cell proliferation capacity in vitro and in vivo and vice versa. Moreover, the overexpression of lincRNA-p21 induced G1 arrest and apoptosis. Knockdown NF-YA expression reversed tumor suppressor activation of lincRNA-p21 in mutant p53 cells, not wild-type p53 cells. A negative correlation was observed between lincRNA-p21 and the phosphorylation of signal transducer and activator of transcription 3 (p-STAT3) in HNSCC tissues. High lincRNA-p21 expression inhibited Janus kinase 2 (JAK2)/STAT3 signal activation and vice versa. Further, we observed direct binding to STAT3 by lincRNA-p21 in HNSCC cells, which suppressed STAT3-induced oncogenic potential.

Conclusions

Our results revealed the transcriptional regulation of lincRNA-p21 by the mutant p53/NF-YA complex in HNSCC. LincRNA-p21 acted as a tumor suppressor in HNSCC progression, which was attributed to direct binding to STAT3 and blocking of JAK2/STAT3 signaling.

Electronic supplementary material

The online version of this article (10.1186/s12943-019-0993-3) contains supplementary material, which is available to authorized users.

Corticotropin-releasing factor suppresses glioma progression by upregulation of long non-coding RNA-p21

Corticotropin-releasing factor (CRF) plays a key role in neuroendocrine regulation of hypothalamo-pituitary-adrenal axis under normal condition and stress by binding to CRF receptor1 (CRFR1). CRF and its receptors have been reported in many types of tumors. Little is known about the role of CRF in the development of glioma. And lincRNA-p21 was reported to act as a role in progression of some cancers. The aim of the present study was to investigate the levels of CRF in glioma, and explore the link between CRF and lincRNA-p21 in this disease. In this study, we found CRF mRNA expression was significantly down-regulated in glioma mice. Moreover, CRF could suppress the proliferation of glioma cells and promote the expression of lincRNA-p21. Afterwards, lincRNA-p21 repressed the proliferation and invasion of glioma cells, which was reversed by miR-34c targeted with 3'-UTR. Furthermore, miR-34c decreased the expression of CRFR1 by binding with the 3'-UTR, which interact with CRF to inhibit the proliferation of glioma cells. Together, these results CRF plays as an important role in glioma progression and metastasis through activation of lincRNA-p21, providing a novel insight for the pathogenesis and underlying therapeutic target for glioma.

Long intergenic noncoding RNA-p21 inhibits apoptosis by decreasing PUMA expression in non-small cell lung cancer

OBJECTIVE

Long noncoding RNAs (lncRNAs) are important mediators in tumor progression. Long intergenic noncoding RNA-p21 (lincRNA-p21) participates in multiple biological processes. This study explored the role of lincRNA-p21 in human non-small cell lung cancer (NSCLC) progression and potential regulatory mechanisms.

METHODS

LincRNA-p21 expression in NSCLC tissues and cell lines (A549, H1299, H1650, and NCI-H2087) was determined by quantitative real-time PCR. LincRNA-p21 overexpressing and sh-lincRNA-p21 lentiviral were respectively transfected into H1299 and A549 cells. Flow cytometry was used to measure apoptosis. Microarray analysis and RNA pull-down assay were used to predict the target genes of lincRNA-p21. Finally, PUMA siRNA and overexpressing PUMA were transfected into NSCLC cells, and the extent of cell apoptosis was measured. The protein expression levels of the relative genes were confirmed by western blot analysis.

RESULTS

LincRNA-p21 was significantly upregulated in NSCLC tissues and cells. The upregulation of lincRNA-p21 considerably inhibited cell apoptosis while the downregulation of lincRNA-p21 showed the opposite effect. PUMA was a direct target gene of lincRNA-p21 and was negatively correlated with lincRNA-p21 in NSCLC specimens. The anti-apoptotic effect of lincRNA-p21 can be effectively attenuated by the upregulation of PUMA.

CONCLUSION

LincRNA-p21 is aberrantly upregulated in NSCLC and inhibits cell apoptosis by decreasing PUMA expression.

Down-Regulated LncRNA-HOTAIR Suppressed Colorectal Cancer Cell Proliferation, Invasion, and Migration by Mediating p21

BACKGROUND AND AIM

HOX transcript antisense intergenic RNA (HOTAIR) is a relatively well-understood RNA, which plays a central role in the pathogenesis of various tumors. The aim of the present study was to investigate the effect by which HOTAIR acts to influence the biological processes of colorectal cancer (CRC) through p21.

METHODS

Reverse transcription quantitative polymerase chain reaction and Western blot methods were employed to provide verification regarding the changes in HOTAIR, PCNA, Ki67, p21, cyclin E, and CDK2 among the CRC tissues and cells. The correlation between the clinicopathological characteristics of patients and expression of HOTAIR and p21 was subsequently evaluated, followed by an analysis into the effects of HOTAIR on the biological processes of M5 cells.

RESULTS

HOTAIR was found to be expressed at high levels, while p21 was determined to be at a low level among both the CRC tissues and the CRC cell lines. The expressions of HOTAIR and p21 were determined to be related to lymph node metastasis, tumor node metastasis, Dukes staging, distant metastases, histological types, and the degree of differentiation. Cells transfected with HOTAIR siRNA displayed inhibited rates of proliferation, invasion, and migration, as well as decreased cyclin E and CDK2, while apoptosis and p21 were increased.

CONCLUSION

The principal findings demonstrated that down-regulation of HOTAIR elicits an inhibitory effect on proliferation, invasion, and migration, while promoting the apoptosis of CRC cells through the up-regulation of p21. We believe that HOTAIR could represent a novel target for the treatment of CRC.

Emerging roles of long non-coding RNA in cancer

Since comprehensive analysis of the mammalian genome revealed that the majority of genomic products are transcribed in long non‐coding RNA (lncRNA), increasing attention has been paid to these transcripts. The applied next‐generation sequencing technologies have provided accumulating evidence of dysregulated lncRNA in cancer. The implication of this finding can be seen in many forms and at multiple levels. With impacts ranging from integrating chromatin remodeling complexes to regulating transcription and post‐transcriptional processes, aberrant expression of lncRNA may have repercussions in cell proliferation, tumor progression or metastasis. lncRNA may act as enhancers, scaffolds or decoys by physically interacting with other RNA species or proteins, resulting in a direct impact on cell signaling cascades. Even though their functional classification is well‐established in the context of cancer, clearer characterization in terms of their phenotypic outputs is needed to optimize and identify suitable candidates that enable the development of new therapeutic strategies and the design of novel diagnostic approaches. The present article aims to outline different cancer‐associated lncRNA according to their contribution to tumor suppression or tumor promotion based on their most current functional annotations.

Roles of long noncoding RNAs in colorectal cancer metastasis

Colorectal cancer (CRC) is the 3^rd most common malignancies worldwide. Metastasis is responsible for more than 90% CRC patients' death. Long noncoding RNAs (lncRNAs) are an important class of transcribed RNA molecules greater than 200 nucleotides in length. With the development of whole genome sequencing technologies, they have been gained more attention. Accumulating evidences suggest that abnormal expression of lncRNAs in diverse diseases are involved in various biological functions such as proliferation, apoptosis, metastasis and differentiation by acting as epigenetic, splicing, transcriptional or post-transcriptional regulators. Aberrant expression of lncRNAs has also been found in CRC. Besides, recent studies have indicated that lncRNAs play important roles in tumourigenesis and cancer metastasis. They participate in the process of metastasis by activing or inhibiting the metastatic pathways. However, their functions on the development of cancer metastasis are poorly understood. In this review, we highlight the findings of roles for lncRNAs in CRC metastasis and review the metastatic pathways of lncRNAs leading to cancer metastasis in CRC, including escape of apoptosis, epithelial-mesenchymal transition (EMT), angiogenesis and invasion, migration and proliferation. Furthermore, we also discuss the potential clinical application of lncRNAs in CRC as diagnostic markers and therapeutic targets.

Linc00659, a long noncoding RNA, acts as novel oncogene in regulating cancer cell growth in colorectal cancer

Background

Colorectal cancer (CRC) is one of the most common cancers and causes of cancer-related death worldwide. In patients with CRC, metastasis is a crucial problem that leads to treatment failure and is the primary cause of the lethality of colon cancer. Long noncoding RNAs (lncRNAs) have recently emerged as critical molecules in the development, cell growth, apoptosis, and metastasis of CRC.

Method

We investigated the transcriptome profiles of human lncRNAs in the primary tumor tissues and in the corresponding normal mucosa of two patients with CRC by using a microarray approach. The expression levels of lncRNAs were verified in colon cancer by real-time PCR. Using bioinformatics approach to illustrate putative biological function of Linc00659 in colon cancer. The effects of Linc00659 on cell growth, proliferation, cell cycle and apoptosis were studies by in vitro assays.

Results

Our data revealed that compared with adjacent normal tissues, 201 lncRNAs were deregulated (fold change ≥ 4 or ≤ 0.25) in CRC tissues. Among them, the expression levels of Linc00659 were significantly increased in colon cancer, and high expression levels were correlated with poor survival in patients with CRC. Bioinformatics analysis results indicated that Linc00659 was significantly coexpressed with cycle-related genes in CRC. Linc00659 expression knockdown could significantly suppress colon cancer cell growth by impairing cell cycle progression. In addition, our results showed that Linc00659 expression knockdown could accelerate cell apoptosis in colon cancer cells treated with chemotherapy drugs. Meanwhile, our results also demonstrated that silencing of Linc00659 expression leads to cell growth inhibition and induced apoptosis, possibly by suppressing PI3K-AKT signaling in colon cancer.

Conclusion

Linc00659 is a novel oncogenic lncRNA involved in colon cancer cell growth by modulating the cell cycle. Our findings give an insight into lncRNA regulation and provide an application for colon cancer therapy.

Electronic supplementary material

The online version of this article (10.1186/s12943-018-0821-1) contains supplementary material, which is available to authorized users.

Therapeutic Targeting of Long Non-Coding RNAs in Cancer

Long non-coding RNAs (lncRNAs) represent a significant population of the human transcriptome. Many lncRNAs exhibit cell- and/or tissue/tumor-specific expression, making them excellent candidates for therapeutic applications. In this review we discuss examples of lncRNAs that demonstrate the diversity of their function in various cancer types. We also discuss recent advances in nucleic acid drug development with a focus on oligonucleotide-based therapies as a novel approach to inhibit tumor progression. The increased success rates of nucleic acid therapeutics provide an outstanding opportunity to explore lncRNAs as viable therapeutic targets to combat various aspects of cancer progression.

Long non-coding RNAs LOC285194, RP11-462C24.1 and Nbla12061 in serum provide a new approach for distinguishing patients with colorectal cancer from healthy controls

Colorectal cancer (CRC) is currently the most prevalent malignant cancer worldwide. However, there is a lack of efficient biomarkers for CRC screening. Accumulating evidence reveals that long non-coding RNAs (lncRNAs) detectable in serum are associated with the genesis and development of various types of cancer. Therefore, we examined the diagnostic ability of lncRNAs in blood samples from patients with CRC by evaluating the levels of 17 CRC- or gastrointestinal cancer-related lncRNAs in serum samples from 71 CRC patients and 70 healthy individuals using reverse transcription-quantitative polymerase chain reaction (RT-qPCR). We detected 13 lncRNAs in serum, three of which displayed significantly different levels between CRC patients and healthy controls. A three-lncRNA signature (LOC285194, RP11-462C24.1 and Nbla12061) identified via stepwise regression analysis showed potential as a diagnostic marker for CRC. The area under the receiver operating characteristic curve of this signature for distinguishing CRC patients from healthy individuals was 0.793 (95% CI: 0.709 to 0.861). The diagnostic ability of this marker was much higher than that of conventional blood biomarkers such as carcinoembryonic antigen (CEA), carbohydrate antigen 199 (CA199), carbohydrate antigen 125 (CA125) and carbohydrate antigen 724 (CA724). Combining this novel marker with conventional biomarkers produced even greater diagnostic ability. Furthermore, the levels of the three lncRNAs decreased after the patients underwent surgical resection. The results of this study suggest an additional marker for CRC screening and provide new directions for further investigation.

Critical effects of long non-coding RNA on fibrosis diseases

The expression or dysfunction of long non-coding RNAs (lncRNAs) is closely related to various hereditary diseases, autoimmune diseases, metabolic diseases and tumors. LncRNAs were also recently recognized as functional regulators of fibrosis, which is a secondary process in many of these diseases and a primary pathology in fibrosis diseases. We review the latest findings on lncRNAs in fibrosis diseases of the liver, myocardium, kidney, lung and peritoneum. We also discuss the potential of disease-related lncRNAs as therapeutic targets for the clinical treatment of human fibrosis diseases.

LincRNA-p21 suppresses development of human prostate cancer through inhibition of PKM2

OBJECTIVES

Previously, we found that long intergenic non-coding RNA-p21 (lincRNA-p21) inhibited the development of human prostate cancer. However, the underlying molecular mechanisms are poorly understood. Here, we attempted to investigate the downstream targets of lincRNA-p21 in prostate cancer.

MATERIALS AND METHODS

Expression of lincRNA-p21 and PKM2 was determined by qRT-PCR and Western blot. Lentivirus expressing shPKM2 or shCtrl was used to explore the role of PKM2 on the enhanced cell proliferation and glycolysis of lincRNA-p21-silenced prostate cancer cells. A xenograft mouse model was performed to investigate the effect of PKM2 suppression, glycolytic or mammalian target of rapamycin (mTOR) inhibitor on the tumorigenic capacity of lincRNA-p21-silenced prostate cancer cells.

RESULTS

We revealed that lincRNA-p21 silencing in DU145 and LNCaP cells induced up-regulation of PKM2 and activation of glycolysis, which could be reversed by PKM2 knockdown or rapamycin treatment. We also found that the proliferation and tumorigenesis of lincRNA-p21-silenced prostate cancer cells were significantly inhibited after knocking down PKM2. 3-bromopyruvate (3-Brpa) or rapamycin treatment largely decreased the tumour burden. Importantly, PKM2 expression was inversely correlated with the lincRNA-p21 level and the survival of prostate cancer patients.

CONCLUSIONS

We demonstrated that lincRNA-p21 blunted the prostate cancer cell proliferation and tumorigenic capacity through down-regulation of PKM2. Therefore, targeting PKM2 or glycolysis might be a therapeutic strategy in prostate cancer patients with lowly expressed lincRNA-p21.

Long non-coding RNAs: a rising biotarget in colorectal cancer

Colorectal cancer (CRC) is a common gastrointestinal cancer, with a high incidence and high mortality. Long non-coding RNAs (lncRNAs) are involved in the development, invasion and metastasis, early diagnosis, prognosis, the chemoresistance and radioresistance of CRC through interference with mRNA activity, directly combining with proteins to regulate their activity or alter their localization, influencing downstream gene expression by inhibiting RNA polymerase and regulating gene expression as competing endogenous RNAs. Recent progress in next generation sequencing and transcriptome analysis has revealed that tissue and cancer-type specific lncRNAs could be useful prognostic markers. Here, the CRC-associated lncRNAs from recent studies until October 2016 are reviewed and multiple studies that have confirmed CRC-associated lncRNAs are summarized. This review may be helpful in understanding the overall relationships between the lncRNAs involved in CRC.

A novel SNP in promoter region of RP11-3N2.1 is associated with reduced risk of colorectal cancer

Single-nucleotide polymorphisms (SNPs) in the promoter region of long intergenic non-coding RNAs (lincRNAs) could play a regulatory role in its expression level and then get involved in colorectal cancer (CRC). Thus, we conducted a two-stage case-control study to investigate the associations of Tag SNPs within the promoter region of selected lincRNAs from microarray data with risk of CRC. A total of 320 cases and 319 controls were recruited in the test set to explore the associations between 16 SNPs with no deviations from Hardy-Weinberg equilibrium (HWE) and risk of CRC. Furthermore, 501 cases and 538 controls were included as the validation set to confirm the significant associations. RP11-3N2.1 rs13230517 polymorphism was found to be negatively associated with CRC in both test set (AA vs. GG, OR = 0.68, 95% CI = 0.48-0.96) and validation set (AA vs. GG, OR = 0.76, 95% CI = 0.59-0.98). Pooled analysis showed that individuals with GA/AA genotypes had a significantly decreased risk of CRC when compared with those carrying GG genotype (OR = 0.74, 95% CI = 0.60-0.90) in the combined set. The crossover analysis revealed that rs13230517 GA/AA carriers had a decreased risk of CRC than GG carriers among non-drinkers in both test and combined set. However, no gene-environment multiplicative interactions were found on risk of CRC. Our findings suggest that rs13230517 polymorphism might participate in the pathogenesis of CRC and have the potential to be a biomarker for predicting the risk of CRC.

Long non-coding RNAs in Colorectal Cancer: Progression and Future Directions

Identification of the colorectal adenoma-carcinoma sequence with its corresponding genetic and epigenetic alterations has significantly increased our knowledge of the etiopathogenesis of colorectal cancer (CRC). However, the molecular mechanisms of colorectal carcinogenesis and metastasis haven't been clearly elucidated. Long non-coding ribonucleic acids (lncRNAs) are key participants of gene regulations rather than “noises”. Accumulative studies have implicated that the aberrant expressions of lncRNAs are tightly corelated to CRC screening, diagnosis, prognosis and therapeutic outcomes. Our review focuses on recent findings on the involvement of lncRNAs in CRC oncogenesis and the lncRNA-based clinical implications in patients with CRC.

Roles of Long Noncoding RNAs in Recurrence and Metastasis of Radiotherapy-Resistant Cancer Stem Cells

Radiotherapy is a well-established therapeutic regimen applied to treat at least half of all cancer patients worldwide. Radioresistance of cancers or failure to treat certain tumor types with radiation is associated with enhanced local invasion, metastasis and poor prognosis. Elucidation of the biological characteristics underlying radioresistance is therefore critical to ensure the development of effective strategies to resolve this issue, which remains an urgent medical problem. Cancer stem cells (CSCs) comprise a small population of tumor cells that constitute the origin of most cancer cell types. CSCs are virtually resistant to radiotherapy, and consequently contribute to recurrence and disease progression. Metastasis is an increasing problem in resistance to cancer radiotherapy and closely associated with the morbidity and mortality rates of several cancer types. Accumulating evidence has demonstrated that radiation induces epithelial–mesenchymal transition (EMT) accompanied by increased cancer recurrence, metastasis and CSC generation. CSCs are believed to serve as the basis of metastasis. Previous studies indicate that CSCs contribute to the generation of metastasis, either in a direct or indirect manner. Moreover, the heterogeneity of CSCs may be responsible for organ specificity and considerable complexity of metastases. Long noncoding RNAs (lncRNAs) are a class of noncoding molecules over 200 nucleotides in length involved in the initiation and progression of several cancer types. Recently, lncRNAs have attracted considerable attention as novel critical regulators of cancer progression and metastasis. In the current review, we have discussed lncRNA-mediated regulation of CSCs following radiotherapy, their association with tumor metastasis and significance in radioresistance of cancer.