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

The role of long non-coding RNA in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a prevalent liver malignancy with complex etiology and generally poor prognosis. Recently, long non-coding RNAs (lncRNAs), non-protein-coding RNA molecules exceeding 200 nucleotides, have emerged as pivotal players in HCC, influencing its initiation, progression, invasion, and metastasis. These lncRNAs modulate gene expression at epigenetic, transcriptional, and post-transcriptional levels, actively participating in the pathological and physiological processes of HCC. Understanding the intricate relationship between lncRNAs and HCC is important for improving prognosis and reducing mortality. This review summarizes advancements in elucidating the role of lncRNAs in HCC pathogenesis.

Interplay of miRNAs and lncRNAs in STAT3 signaling pathway in colorectal cancer progression

In recent decades, colorectal cancer (CRC) has turned into one of the most widespread malignancies, and the incidence of this malignancy is expected to increase. Despite considerable improvements in therapeutic approaches, the prognosis, and the management of CRC face many problems. Likely, the main limitation in the successful treatment of CRC is the lack of appropriate clinical therapeutic targets. As an effective target, the signal transducer and activator of transcription 3 (STAT3) are regulated by a wide range of genes and involved in cellular processes, including cell growth, migration, invasion, immunosuppression, and angiogenesis. Aberrant regulation of STAT3 signaling leads to cellular dysfunction, diseases, and malignancies, including CRC. Consequently, targeting this signaling pathway is considered one of the therapeutic strategies used in CRC treatment. MicroRNAs (miRNAs) and long non-coding RNAs (lncRNAs) are non-coding RNA molecules with partial or no protein-coding activity that participate in gene regulation at epigenetic, transcriptional, and post-transcriptional levels and regulate multiple signaling pathways, including STAT3 signaling (especially JAK/STAT). Therefore, these regulatory molecules are suggested to be very promising targets to present new insights into overcoming the limitations of conventional therapeutic strategies. Therefore, the current review study aimed to summarize the therapeutic and diagnostic significance of miRNAs and lncRNAs and their therapeutic and diagnostic significance related to the expression and activity of STAT3 in CRC.

CDKN2B-AS1 as a novel therapeutic target in cancer: Mechanism and clinical perspective

Long non-coding RNAs (lncRNA) have been identified as essential components having considerable modulatory impactson biological activities through altering gene transcription, epigenetic changes, and protein translation. Cyclin-dependent kinase inhibitor 2B antisense RNA 1 (CDKN2B-AS1), a recently discovered lncRNA, was shown to be substantially elevated in various cancers.Furthermore, via modulation ofvarious signalingaxes, it is effectively connected to the control of critical cancer-associatedbiological pathways likecell proliferation, apoptosis, cell cycle, epithelial-mesenchymal transition(EMT), invasion, and migration. Considering the crucial functions ofCDKN2B-AS1in cancer onset and development, this lncRNA offers immense therapeutic implications for usage as a new diagnostic or treatment approach. In this article, we evaluate the most recent discoveries made into the functions of the lncRNA CDKN2B-AS1 in cancer, in addition to its prospect asbeneficial properties,prognostic anddiagnostic biomarkersin the cancer-related treatment, emphasizingits participation in a broad network of signalingaxes whichcould affectvariouscancers and investigating its promising therapeutic possibility.

Targeting lncRNAs of colorectal cancers with natural products

Non-coding RNA (ncRNA) is one of the functional classes of RNA that has a regulatory role in various cellular processes, such as modulation of disease onset, progression, and prognosis. ncRNAs, such as microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs), have been actively studied in recent years. The change in ncRNA levels is being actively studied in numerous human diseases, especially auto-immune disorders and cancers; however, targeting and regulating ncRNA with natural products to cure cancer has not been fully established. Recently many groups reported the relationship between ncRNA and natural products showing promising effects to serve as additional therapeutic approaches to cure cancers. This mini-review summarizes the aspects of lncRNAs related to cancer biology focusing on colorectal cancers that natural products can target.

IGFL2-AS1, a Long Non-Coding RNA, Is Associated with Radioresistance in Colorectal Cancer

Precise prediction of radioresistance is an important factor in the treatment of colorectal cancer (CRC). To discover genes that regulate the radioresistance of CRCs, we analyzed an RNA sequencing dataset of patient-originated samples. Among various candidates, IGFL2-AS1, a long non-coding RNA (lncRNA), exhibited an expression pattern that was well correlated with radioresistance. IGFL2-AS1 is known to be highly expressed in various cancers and functions as a competing endogenous RNA. To further investigate the role of IGFL2-AS1 in radioresistance, which has not yet been studied, we assessed the amount of IGFL2-AS1 transcripts in CRC cell lines with varying degrees of radioresistance. This analysis showed that the more radioresistant the cell line, the higher the level of IGFL2-AS1 transcripts-a similar trend was observed in CRC samples. To directly assess the relationship between IGFL2-AS1 and radioresistance, we generated a CRC cell line stably expressing a small hairpin RNA (shRNA) targeting IGFL2-AS1. shRNA-mediated knockdown of IGFL2-AS1 decreased radioresistance and cell migration in vitro, establishing a functional role for IGFL2-AS1 in radioresistance. We also showed that downstream effectors of the AKT pathway played crucial roles. These data suggest that IGFL2-AS1 contributes to the acquisition of radioresistance by regulating the AKT pathway.

LncRNA ALMS1-IT1 is a novel prognostic biomarker and correlated with immune infiltrates in colon adenocarcinoma

Colon adenocarcinoma (COAD) is one of the most serious cancers. It is important to accurately predict prognosis and provide individualized treatment. Evidence suggests that clinicopathological features and immune status of the body are related to the occurrence and development of cancer. Expression of long non-coding RNA (LncRNA) ALMS1 intronic transcript 1 (ALMS1-IT1) is observed in some cancer types, and we believe that it may have the potential to serve as a marker of COAD. Therefore, we used the data obtained from the cancer genome atlas (TCGA) database to prove the relationship between ALMS1-IT1 and COAD. Wilcoxon rank sum test, Chi-square test, Fisher exact test and logistic regression were used to evaluate relationships between clinical-pathologic features and ALMS1-IT1 expression. Receiver operating characteristic curves were used to describe binary classifier value of ALMS1-IT1 using area under curve score. Kaplan-Meier method and Cox regression analysis were used to evaluate factors contributing to prognosis. Gene oncology (GO) and (Kyoto Encyclopedia of Genes and Genomes) KEGG enrichment analysis were used to predict the function of differentially expressed genes associated with ALMS1-IT1. Gene set enrichment analysis (GSEA) was used to predict canonical pathways associated with ALMS1-IT1.Immune infiltration analysis was performed to identify the significantly involved functions of ALMS1-IT1. Starbase database was used to predict miRNAs and RNA binding proteins (RBPs) that may interact with ALMS1-IT1. Increased ALMS1-IT1 expression in COAD was associated with N stage (P < .001), M stage (P = .003), Pathologic stage (P = .002), and Primary therapy outcome (P = .009). Receiver operating characteristic curve suggested the significant diagnostic and prognostic ability of ALMS1-IT1 (area under curve = 0.857). High ALMS1-IT1 expression predicted a poorer overall-survival (P = .005) and poorer progression-free interval (PFI) (P = .012), and ALMS1-IT1 expression was independently correlated with PFI in COAD patients (hazard ratio (HR) :1.468; 95% CI: 1.029-2.093; P =.034) (HR: 1.468; 95% CI: 1.029-2.093; P = .034). GO, KEGG, GSEA, and immune infiltration analysis showed that ALMS1-IT1 expression was correlated with regulating the function of DNA and some types of immune infiltrating cells. ALMS1-IT1 expression was significantly correlated with poor survival and immune infiltrations in COAD, and it may be a promising prognostic biomarker in COAD.

Notch-associated lncRNAs profiling circuiting epigenetic modification in colorectal cancer

Background

Colorectal cancer (CRC) is one of the most prevalent digestive cancers, ranking the 2nd cause of cancer-related fatality worldwide. The worldwide burden of CRC is predicted to rise by 60% by 2030. Environmental factors drive, first, inflammation and hence, cancer incidence increase.

Main

The Notch-signaling system is an evolutionarily conserved cascade, has role in the biological normal developmental processes as well as malignancies. Long non-coding RNAs (LncRNAs) have become major contributors in the advancement of cancer by serving as signal pathways regulators. They can control gene expression through post-translational changes, interactions with micro-RNAs or down-stream effector proteins. Recent emerging evidence has emphasized the role of lncRNAs in controlling Notch-signaling activity, regulating development of several cancers including CRC.

Conclusion

Notch-associated lncRNAs might be useful prognostic biomarkers or promising potential therapeutic targets for CRC treatment.

Therefore, here-in we will focus on the role of “Notch-associated lncRNAs in CRC” highlighting “the impact of Notch-associated lncRNAs as player for cancer induction and/or progression.”

Graphical Abstract

Analysis of LINC01314 and miR-96 Expression in Colorectal Cancer Patients via Tissue Microarray-Based Fluorescence In Situ Hybridization

Methods

A tissue microarray (TMA) containing 76 individual colorectal tumor samples and 28 adjacent normal samples was constructed, and the expression levels of LINC01314 and miR-96 were detected by fluorescence in situ hybridization.

Results

The expression levels of both LINC01314 and miR-96 were upregulated in CRC tissues and were associated with vascular metastasis (p < 0.05). A significantly positive correlation was observed between LINC01314 and miR-96 expression in tumor tissues (p < 0.001, r = 0.870). Dominant expression of LINC01314 was a risk factor for both blood vessel invasion (p < 0.05) and poor 5-year survival (p = 0.001, hazard ratio = 4.144). The Kaplan-Meier analysis indicated that patients with LINC01314-dominant expression exhibited worse 5-year survival rates than those with miR-96-dominant expression (p < 0.05).

Conclusion

The expression patterns of both LINC01314 and miR-96 may be diagnostic of, and prognostic for, CRC. These findings will facilitate further exploration of the molecular mechanism of lncRNAs in CRC.

Curcumin Targeting Non-Coding RNAs in Colorectal Cancer: Therapeutic and Biomarker Implications

Colorectal cancer is one of the most common gastrointestinal malignancies, with high incidence rates, a low rate of early diagnosis, and complex pathogenesis. In recent years, there has been progress made in its diagnosis and treatment methods, but tumor malignant proliferation and metastasis after treatment still seriously affect the survival and prognosis of patients. Therefore, it is an extremely urgent task of current medicine to find new anti-tumor drugs with high efficiency and safety and low toxicity. Curcumin has shown potent anti-tumor and anti-inflammatory effects and is considered a hot spot in the research and development of anti-tumor drugs due to its advantages of precise efficacy, lower toxic side effects, and less drug resistance. Recent studies have revealed that curcumin has anti-tumor effects exerted on the epigenetic regulation of tumor-promoting/tumor-suppressing gene expression through the alteration of expression levels of non-coding RNAs (e.g., lncRNAs, miRNAs, and circRNAs). Herein, we summarize the interaction between curcumin and non-coding RNAs on the occurrence and development of colorectal cancer. The information complied in this review will serve as a scientific and reliable basis and viewpoint for the clinical application of non-coding RNAs in colorectal cancer.

Long non-coding RNA NR2F2-AS1: its expanding oncogenic roles in tumor progression

Long non-coding RNA (LncRNA) is a new type of non-coding RNA whose transcription is more than 200 nucleotides in length and can be up to 100 kb. The crucial regulatory function of lncRNAs in different cellular processes is now notable in many human diseases, especially in different steps of tumorigenesis, making them clinically significant. This research tried to collect all evidence obtained so far regarding Nuclear Receptor subfamily 2 group F member 2 Antisense RNA 1 (NR2F2-AS1) to explore its role in carcinogenesis and molecular mechanism in several cancers. Collecting evidence value an oncogenic role for NR2F2-AS1, whose dysregulation changes the status for cancerous cells to gain the supremacy toward cellular proliferation, dissemination, and ultimately migration. The NR2F2-AS1 acts as competitive endogenous RNA (ceRNA) and contains several microRNA response elements (MREs) for different microRNAs involved in various pathways such as PI3K/AKT, Wnt/β-catenin, and TGF-β. This clinically makes NR2F2-AS1 a remarkable lncRNA which contributes to cancer progression and invasion and perhaps could be a candidate as a prognostic marker or even a therapeutic target.

Non-Coding RNAs Regulate the Resistance to Anti-EGFR Therapy in Colorectal Cancer

Colorectal cancer (CRC) is the third prevalent cancer worldwide, the morbidity and mortality of which have been increasing in recent years. As molecular targeting agents, anti-epidermal growth factor receptor (EGFR) monoclonal antibodies (McAbs) have significantly increased the progression-free survival (PFS) and overall survival (OS) of metastatic CRC (mCRC) patients. Nevertheless, most patients are eventually resistant to anti-EGFR McAbs. With the intensive study of the mechanism of anti-EGFR drug resistance, a variety of biomarkers and pathways have been found to participate in CRC resistance to anti-EGFR therapy. More and more studies have implicated non-coding RNAs (ncRNAs) primarily including microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs), are widely involved in tumorigenesis and tumor progression. They function as essential regulators controlling the expression and function of oncogenes. Increasing data have shown ncRNAs affect the resistance of molecular targeted drugs in CRC including anti-EGFR McAbs. In this paper, we have reviewed the advance in mechanisms of ncRNAs in regulating anti-EGFR McAbs therapy resistance in CRC. It provides insight into exploring ncRNAs as new molecular targets and prognostic markers for CRC.

Molecular Network of Colorectal Cancer and Current Therapeutic Options

Colorectal cancer (CRC), a leading cause of cancer-related mortalities globally, results from the accumulation of multiple genetic and epigenetic alterations in the normal colonic and rectum epithelium, leading to the progression from colorectal adenomas to invasive carcinomas. Almost half of CRC patients will develop metastases in the course of the disease and most patients with metastatic CRC are incurable. Particularly, the 5-year survival rate of patients with stage 4 CRC at diagnosis is less than 10%. Although genetic understanding of these CRC tumors and paired metastases has led to major advances in elucidating early driver genes responsible for carcinogenesis and metastasis, the pathophysiological contribution of transcriptional and epigenetic aberrations in this malignancy which influence many central signaling pathways have attracted attention recently. Therefore, treatments that could affect several different molecular pathways may have pivotal implications for their efficacy. In this review, we summarize our current knowledge on the molecular network of CRC, including cellular signaling pathways, CRC microenvironment modulation, epigenetic changes, and CRC biomarkers for diagnosis and predictive/prognostic use. We also provide an overview of opportunities for the treatment and prevention strategies in this field.

Identification of Key Gene Targets for Sensitizing Colorectal Cancer to Chemoradiation: an Integrative Network Analysis on Multiple Transcriptomics Data

PURPOSE

Colorectal cancer (CRC) is a main cause of morbidity and mortality in the world. Chemoradioresistance is a major problem in CRC treatment. Identification of novel therapeutic targets in order to overcome treatment resistance in CRC is necessary.

METHODS

In this study, gene expression omnibus (GEO) database was searched to find microarray datasets. Data normalization/analyzing was performed using ExAtlas. The gene ontology (GO) and pathway enrichment analysis was performed using g:Profiler. Protein-protein interaction network (PPIN) was constructed by Search Tool for the Retrieval of Interacting Genes (STRING) and analyzed using Cytoscape. Survival analysis was done using Kaplan-Meier curve method.

RESULTS

Forty-one eligible datasets were included in study. A total of 12,244 differentially expressed genes (DEGs) and 7337 unique DEGs were identified. Among them, 1187 DEGs were overlapped in ≥ 3 datasets. Fifty-five overlapped genes were considered as hub genes. Common hub genes in chemo/radiation/chemoradiation datasets were chosen as the essential candidate genes (n = 13). Forty-one hub gene and 7 essential candidate genes were contributed in the significant modules. The modules were mainly enriched in the signaling pathways of senescence, autophagy, NF-κB, HIF-1, stem cell pluripotency, notch, neovascularization, cell cycle, p53, chemokine, and PI3K-Akt. NGFR, FGF2, and PROM1 genes were significantly predictors of CRC patient's survival.

CONCLUSION

Our study revealed three-gene signatures as potential therapeutic targets and also candidate molecular markers in CRC chemoradioresistance.

Role of Curcumin in Regulating Long Noncoding RNA Expression in Cancer

Phytochemicals are various compounds produced by plants. There is growing evidence on their potential health effects. Some of these compounds are considered as traditional medicines and used as painkillers, anti-inflammatory agents, and for other applications. One of these phytochemicals is curumin, a natural polyphenol derived from the turmeric plant (Curcuma longa L.). Curcumin is widely used as a food coloring, preservative and condiment. It has also been shown to have antioxidative and anti-inflammatory effects. Moreover, there is growing evidence that curcumin alters long noncoding RNAs (lncRNAs) in many kinds of cancer. These noncoding RNAs can cause epigenetic modulation in the expression of several genes. This study reviews reports of curcumin effects on lncRNAs in lung, prostate, colorectal, breast, pancreatic, renal, gastric, and ovarian cancers.

The Mechanistic Roles of ncRNAs in Promoting and Supporting Chemoresistance of Colorectal Cancer

Colorectal Cancer (CRC) is one of the most common gastrointestinal malignancies which has quite a high mortality rate. Despite the advances made in CRC treatment, effective therapy is still quite challenging, particularly due to resistance arising throughout the treatment regimen. Several studies have been carried out to identify CRC chemoresistance mechanisms, with research showing different signalling pathways, certain ATP binding cassette (ABC) transporters and epithelial mesenchymal transition (EMT), among others to be responsible for the failure of CRC chemotherapies. In the last decade, it has become increasingly evident that certain non-coding RNA (ncRNA) families are involved in chemoresistance. Research investigations have demonstrated that dysregulation of microRNAs (miRNAs), long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs) contribute towards promoting resistance in CRC via different mechanisms. Considering the currently available data on this phenomenon, a better understanding of how these ncRNAs participate in chemoresistance can lead to suitable solutions to overcome this problem in CRC. This review will first focus on discussing the different mechanisms of CRC resistance identified so far. The focus will then shift onto the roles of miRNAs, lncRNAs and circRNAs in promoting 5-fluorouracil (5-FU), oxaliplatin (OXA), cisplatin and doxorubicin (DOX) resistance in CRC, specifically using ncRNAs which have been recently identified and validated under in vivo or in vitro conditions.

MIR600HG suppresses metastasis and enhances oxaliplatin chemosensitivity by targeting ALDH1A3 in colorectal cancer

Background: Metastasis and chemoresistance indicate a poor prognosis in colorectal cancer (CRC) patients. However, the mechanisms that lead to the development of chemoresistance and metastasis in CRC remain unclear.

Materials and methods: We combined clinical and experimental studies to determine the role of MIR600HG in CRC metastasis and chemoresistance. The statistical analysis was performed using GraphPad Prism software, version 8.0.

Results: We detected down-regulated expression of long non-coding RNA (lncRNA) MIR600HG in CRC specimens and cell lines compared with normal controls, and the expression level of MIR600HG was inversely correlated with the overall survival of CRC patients. The inhibition of MIR600HG stimulated CRC cell metastasis and chemoresistance. In addition, our data showed that the inhibition of MIR600HG stimulated CRC stemness, while the overexpression of MIR600HG suppressed stemness. Importantly, our animal experiments showed that MIR600HG inhibited tumour formation and that the combination of MIR600HG inhibition and oxaliplatin (Oxa) treatment significantly inhibited tumour growth compared with that with either intervention alone. Furthermore, we demonstrated that MIR600HG exerts its anticancer role by targeting ALDH1A3 in CRC.

Conclusions: Our data suggest that MIR600HG functions as a tumour suppressor and that the overexpression of MIR600HG inhibits tumour invasion and enhances chemosensitivity, providing a new strategy for CRC treatment.

lncRNA SNHG4 modulates colorectal cancer cell cycle and cell proliferation through regulating miR-590-3p/CDK1 axis

Colorectal cancer (CRC) is a prevalent malignancy worldwide. The development of genome sequencing technology has allowed the discovery that epigenetic regulation might play a critical role in CRC tumorigenesis. In the present study, we found that the long noncoding RNA (lncRNA) SNHG4 was dramatically increased in CRC tissue samples and cell lines based on both publicly available and experimental data. SNHG4 knockdown suppressed the viability and colony formation capacity of CRC cells. The expression of CDK1 was considerably increased in CRC tissue samples and cells and had a positive correlation with the expression of SNHG4 in CRC. SNHG4 silencing not only caused S phase cell cycle arrest but also significantly downregulated the CDK1, cyclin B1, and cyclin A2 protein levels in CRC cells. miR-590-3p simultaneously bound to SNHG4 and CDK1. miR-590-3p functioned to inhibit CDK1 expression. miR-590-3p overexpression exerted the same effects on the CRC cell phenotype as SNHG4 knockdown. The effects of si-SNHG4 on CRC cells were significantly reversed by anti-miR-590-3p, indicating that SNHG4 relieved the miR-590-3p-induced inhibition of CDK1 by acting as a competing endogenous RNA (ceRNA). In vivo, SNHG4 silencing inhibited subcutaneously transplanted tumor growth and decreased cell cycle marker levels, whereas miR-590-3p inhibition exerted the opposite effects. The in vivo effects of SNHG4 silencing were also reversed by miR-590-3p inhibition. The SNHG4/miR-590-3p/CDK1 axis influences the cell cycle to modulate CRC cell proliferation and subcutaneously transplanted tumor growth. Further application of this axis still requires analysis using more animal models and clinical investigations.

Long Noncoding RNA VPS9D1-AS1 Sequesters microRNA-525-5p to Promote the Oncogenicity of Colorectal Cancer Cells by Upregulating HMGA1

Background

The long noncoding RNA VPS9D1 antisense RNA 1 (VPS9D1-AS1) has emerged as a critical regulator in non-small-cell lung, gastric, and prostate cancers. In this study, we measured the expression levels of VPS9D1-AS1 in colorectal cancer (CRC) and determined the role of VPS9D1-AS1 in regulating the biological activities of CRC cells. In addition, we thoroughly elucidated the molecular mechanism mediating the oncogenic activities of VPS9D1-AS1 in CRC.

Methods

The expression levels of VPS9D1-AS1 in CRC tissues and cell lines were detected via quantitative reverse transcription-polymerase chain reaction. Loss-of-function experiments were performed to detect the effects of VPS9D1-AS1 silencing on CRC cell proliferation, apoptosis, migration, and invasion as well as on tumor growth in vivo. Bioinformatics analysis predicted the potential microRNAs (miRNAs) interacting with VPS9D1-AS1, and this prediction was further confirmed via RNA immunoprecipitation and luciferase reporter assays.

Results

Our results demonstrated the upregulated expression of VPS9D1-AS1 in CRC tissues and cell lines. Functionally, VPS9D1-AS1 interference suppressed CRC cell proliferation, migration, and invasion and promoted cell apoptosis in vitro. In addition, the loss of VPS9D1-AS1 hindered tumor growth in vivo. Mechanistic studies identified VPS9D1-AS1 as a competing endogenous RNA in CRC cells, in which VPS9D1-AS1 acted as a molecular sponge of miR-525-5p and consequently increased the expression of high-mobility group AT-hook 1 (HMGA1). Moreover, rescue experiments revealed that the regulatory effects of VPS9D1-AS1 deficiency on CRC cells were abolished after miR-525-5p inhibition or HMGA1 restoration.

Conclusion

The newly identified competing endogenous RNA pathway involving VPS9D1-AS1, miR-525-5p, and HMGA1 is implicated in the control of CRC progression and may provide an effective target for CRC diagnosis and therapy.

The Liquid Biopsy in the Management of Colorectal Cancer: An Overview

Currently, there is a crucial need for novel diagnostic and prognostic biomarkers with high specificity and sensitivity in patients with colorectal cancer. A "liquid biopsy" is characterized by the isolation of cancer-derived components, such as circulating tumor cells, circulating tumor DNA, microRNAs, long non-coding RNAs, and proteins, from peripheral blood or other body fluids and their genomic or proteomic assessment. The liquid biopsy is a minimally invasive and repeatable technique that could play a significant role in screening and diagnosis, and predict relapse and metastasis, as well as monitoring minimal residual disease and chemotherapy resistance in colorectal cancer patients. However, there are still some practical issues that need to be addressed before liquid biopsy can be widely used in clinical practice. Potential challenges may include low amounts of circulating tumor cells and circulating tumor DNA in samples, lack of pre-analytical and analytical consensus, clinical validation, and regulatory endorsement. The aim of this review was to summarize the current knowledge of the role of liquid biopsy in the management of colorectal cancer.

Clinical diagnostic value of long non-coding RNAs in Colorectal Cancer: A systematic review and meta-analysis

Background: Histopathological diagnosis remains the gold standard for the diagnosis of cancer, including colorectal cancer, but it is infeasible when tumor tissue is not available. With the recognition of long non-coding RNAs (lncRNAs), the expression of lncRNAs in serum or tissue samples has been reported as a diagnosis method for some cancers, however, the diagnostic value of lncRNAs for colorectal cancer remains unclear.

Methods: A systematic review and meta-analysis were conducted. Eligible studies were identified through a comprehensive literature search in PubMed, PubMed Central, Web of Science, Embase, and Cochrane Library (up to May 05, 2020) according to the selection criteria. Meta-DiSc, Review Manager and STATA were used to analyze the association between lncRNAs expression and the diagnosis of colorectal cancer.

Results: Fifteen studies that analyzed the expression of 15 lncRNAs in 1434 CRC patients were included. The summary area under the curve (AUC) of lncRNA for the diagnosis efficacy between patients with and without CRC was estimated to be 0.8629, corresponding to a weighted sensitivity of 0.75 (95% CI: 0.72 - 0.77), specificity of 0.80 (95%CI: 0.78 - 0.82). Subgroup analysis illustrated that the AUC of blood-based detection of lncRNA showed 0.8820, pooled DOR: 18.57, while tissue-based analysis showed 0.8203, pooled DOR: 10.47. Blood-based tests were then divided into two categories, plasma-based and serum-based lncRNA testing. Results revealed that the AUC of serum-based detection was 0.9077, pooled DOR: 26.64, and plasma-based detection was 0.5000, pooled DOR: 11.80.

Conclusions: This meta-analysis indicates that the aberrantly expressed lncRNAs might serve as potential diagnostic biomarkers for CRC patients and blood-based lncRNA analysis is of higher diagnostic accuracy than tissue-based testing. Moreover, serum-based lncRNA testing achieved higher diagnostic efficacy than plasma-based analysis.

A potential prognostic prediction model of colon adenocarcinoma with recurrence based on prognostic lncRNA signatures

BACKGROUND

Colon adenocarcinoma (COAD) is one of the common gastrointestinal malignant diseases, with high mortality rate and poor prognosis due to delayed diagnosis. This study aimed to construct a prognostic prediction model for patients with colon adenocarcinoma (COAD) recurrence.

METHODS

Differently expressed RNAs (DERs) between recurrence and non-recurrence COAD samples were identified based on expression profile data from the NCBI Gene Expression Omnibus (GEO) repository and The Cancer Genome Atlas (TCGA) database. Then, recurrent COAD discriminating classifier was established using SMV-RFE algorithm, and receiver operating characteristic curve was used to assess the predictive power of classifier. Furthermore, the prognostic prediction model was constructed based on univariate and multivariate Cox regression analysis, and Kaplan-Meier survival curve analysis was used to estimate this model. Furthermore, the co-expression network of DElncRNAs and DEmRNAs was constructed followed by GO and KEGG pathway enrichment analysis.

RESULTS

A total of 54 optimized signature DElncRNAs were screened and SMV classifier was constructed, which presented a high accuracy to distinguish recurrence and non-recurrence COAD samples. Furthermore, six independent prognostic lncRNAs signatures (LINC00852, ZNF667-AS1, FOXP1-IT1, LINC01560, TAF1A-AS1, and LINC00174) in COAD patients with recurrence were screened, and the prognostic prediction model for recurrent COAD was constructed, which possessed a relative satisfying predicted ability both in the training dataset and validation dataset. Furthermore, the DEmRNAs in the co-expression network were mainly enriched in glycan biosynthesis, cardiac muscle contraction, and colorectal cancer.

CONCLUSIONS

Our study revealed that six lncRNA signatures acted as an independent prognostic biomarker for patients with COAD recurrence.

LncRNA FOXC2-AS1 enhances FOXC2 mRNA stability to promote colorectal cancer progression via activation of Ca2+-FAK signal pathway

Long noncoding RNAs (lncRNAs) have been confirmed, which are involved in tumorigenesis and metastasis in colorectal cancer (CRC). FOXC2 antisense RNA 1 (FOXC2-AS1) was reported, facilitating the proliferation and progression in several cancers. However, the role of FOXC2-AS1 in CRC cell migration and metastasis is not unclear. In this study, we observed that lncRNA FOXC2-AS1 was upregulated in CRC tissues, and its high expression indicated the poor survival in CRC patients. Meanwhile, FOXC2-AS1 was higher in CRC tissues with metastasis than that of nonmetastatic tumor tissues. We found that FOXC2-AS1 was predominately expressed in the nucleus of tissues and cells. FOXC2-AS1 knockdown suppressed CRC cell growth, invasion, and metastasis in vitro and in vivo. Moreover, FOXC2-AS1 could positively regulate the neighboring gene FOXC2 and stabilized FOXC2 mRNA by forming a RNA duplex. Meanwhile, ectopic expression of FOXC2 could obviously alleviate the suppressed effects caused by silencing FOXC2-AS1. For the mechanism, FOXC2-AS1 knockdown could reduce intracellular Ca²⁺ levels, inhibited FA formation and FAK signaling, and these suppressed effects were mitigated by increasing FOXC2 expression. These results demonstrated that FOXC2-AS1 enhances FOXC2 mRNA stability to promote CRC proliferation, migration, and invasion by activation of Ca²⁺-FAK signaling, which implicates that FOXC2-AS1 may represent a latent effective therapeutic target for CRC progression.

The functional role of long noncoding RNA in resistance to anticancer treatment

Chemotherapy is one of the fundamental methods of cancer treatment. However, drug resistance remains the main cause of clinical treatment failure. We comprehensively review the newly identified roles of long noncoding RNAs (lncRNAs) in oncobiology that are associated with drug resistance. The expression of lncRNAs is tissue-specific and often dysregulated in human cancers. Accumulating evidence suggests that lncRNAs are involved in chemoresistance of cancer cells. The main lncRNA-driven mechanisms of chemoresistance include regulation of drug efflux, DNA damage repair, cell cycle, apoptosis, epithelial-mesenchymal transition (EMT), induction of signaling pathways, and angiogenesis. LncRNA-driven mechanisms of resistance to various antineoplastic agents have been studied extensively. There are unique mechanisms of resistance against different types of drugs, and each mechanism may have more than one contributing factor. We summarize the emerging strategies that can be used to overcome the technical challenges in studying and addressing lncRNA-mediated drug resistance.

Aberrant expression of lncRNA MALAT1 modulates radioresistance in colorectal cancer in vitro via miR-101-3p sponging

Colorectal cancer (CRC) is one of deadly malignancies that affects humans globally. Herein, the effects of MALAT1 on CRC cellular functions were investigated. RT-qPCR measured expression of MALAT1 in human cell lines for colorectal Cancer. Radiation-resistance CRC cells (CRC-IR) were generated by increasing treatments of irradiation. Cell transfection upregulated or silenced genes in CRC-IR cells so as to study the correlation between MALAT1/miR-101-3p expression and cellular resistance to irradiation through evaluation of CCK-8, FCM apoptosis, Transwell migration and invasion and western blot assays for cell viability,apoptosis, migration and invasion and EMT. MALAT1 was upregulated in radio-resistance cell lines compared to normal CRC cells and upregulation promoted cell viability. In addition, decreased MALAT1 inhibited cell proliferation and metastasis and promoted apoptosis of CRC-IR cells. The luciferase assays confirmed that MALAT1 targeted and regulated miR-101-3p expression in radio-resistance cells. MiR-101-3p counteracted the effect exerted by MALAT1 in CRC-IR cells, indicating that MALAT1 added to the radio-resistance in vitro while miR-101-3p mimics could decrease the resistance to irradiation in CRC. In this study we have demonstrated that MALAT1 could regulate the radio-resistance in colorectal cancer via sponging miR-101-3p. Eventually, these outcomes unearthed a novel axis lncRNA MALAT1/miR-101-3p,which might be a prospective treatment to regulate radio-therapy in the near future.

Abnormal bowel movement frequency increases the risk of rectal cancer: evidence from cohort studies with one million people

Previous studies from case-control studies failed to draw reliable conclusions regarding the relationship between bowel movement frequency and the risk of colorectal cancer. To further examine this relationship, we collect the data from cohort studies that make a more accurate estimation. Several online data were searched from inception to February 29, 2020. Ten cohort studies involving 1,038,598 individuals were included in our study. The pooled results indicated that a bowel movement of less than once per day was not associated with the risk of colorectal cancer (relative risk (RR)= 1.00, 95% confidence interval (CI): 0.87-1.16, P = 0.950) compared with that of once per day. Compared with a bowel movement frequency of once per day, a bowel movement of more than once per day was also not related to elevated risk of colorectal cancer (RR = 1.04, 95% CI: 0.91-1.19, P = 0.570). The subgroup analyses indicated a low or high bowel movement frequency did not increase the risk of colon cancer (RR = 0.91, 95% CI: 0.80-1.03, P = 0.130). However, an increased frequency of bowel movements increased the risk of rectal cancer (RR = 1.34, 95% CI: 1.19-1.52, P < 0.001). The sensitivity analysis still supports the results. No significant publication bias existed. The data from cohort indicated that less bowel movement frequency was not associated with the risk of colorectal cancer. The frequency of bowel movement affects the risk of rectal cancer.

Promoter Hypomethylation and Increased Expression of the Long Non-coding RNA LINC00152 Support Colorectal Carcinogenesis

Up-regulation of the long non-coding RNA LINC00152 can contribute to cancer development, proliferation and invasion, including colorectal cancer, however, its mechanism of action in colorectal carcinogenesis and progression is only insufficiently understood. In this work we correlated LINC00152 expression with promoter DNA methylation changes in colorectal tissues along the normal-adenoma-carcinoma sequence and studied the effects of LINC00152 silencing on the cell cycle regulation and on the whole transcriptome in colon carcinoma cells using cell and molecular biology techniques. LINC00152 was significantly up-regulated in adenoma and colorectal cancer (p < 0.001) compared to normal samples, which was confirmed by real-time PCR and in situ hybridization. LINC00152 promoter hypomethylation detected in colorectal cancer (p < 0.01) was strongly correlated with increased LINC00152 expression (r=-0.90). Silencing of LINC00152 significantly suppressed cell growth, induced apoptosis and decreased cyclin D1 expression (p < 0.05). Whole transcriptome analysis of LINC00152-silenced cells revealed significant down-regulation of oncogenic and metastasis promoting genes (e.g. YES proto-oncogene 1, PORCN porcupine O-acyltransferase), and up-regulation of tumour suppressor genes (e.g. DKK1 dickkopf WNT signalling pathway inhibitor 1, PERP p53 apoptosis effector) (adjusted p < 0.05). Pathway analysis confirmed the LINC00152-related activation of oncogenic molecular pathways including those driven by PI3K/Akt, Ras, WNT, TP53, Notch and ErbB. Our results suggest that promoter hypomethylation related overexpression of LINC00152 can contribute to the pathogenesis of colorectal cancer by facilitating cell progression through the up-regulation of several oncogenic and metastasis promoting pathway elements.

Association of lncRNA-p53 regulatory network (lincRNA-p21, lincRNA-ROR and MALAT1) and p53 with the clinicopathological features of colorectal primary lesions and tumors

Colorectal cancer (CRC) is a common intestinal cancer with a high mortality rate. Early detection of this type of cancer is fundamental to the prevention of the disease, which results in improved survival rates. In the human colon tissue, transition from normal epithelium to adenoma is considered to be caused by unknown molecular incidents occurring over 5-10 years. The detection of CRC has proved problematic when in the early stages of disease. In addition, identifying suitable biomarkers for the detection of CRC progress in patients remains one of the most significant challenges. Long non-coding RNAs have been demonstrated to contribute to the promotion of CRC. The aim of the present study was to investigate the clinical and biological significance of long intergenic non-coding (linc)RNA-p21, lincRNA-regulator of reprogramming (ROR) and metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) in the colon tumor and polyp tissue, and the association that these have with the expression of p53 at the mRNA level. Neoplastic and paired adjacent normal tissue samples were obtained from 72 patients (46 polyps and 26 tumors). Reverse transcription-quantitative PCR was performed to determine the relative fold changes in the expression of lincRNA-p21, lincRNA-RoR, MALAT1 and p53 in the samples. A significant association was observed between the levels of MALAT1 and p53 in neoplasm tissues (R=0.073; P<0.05). The relative expression of the MALAT1 gene revealed a statistically significant difference between the different polyp types and number of polyps (P=0.0028 and 0.022, respectively). Adjuvant therapy in patients with tumors revealed an association between the levels of lincRNA-ROR and lincRNA-p21 expression (P=0.015 and 0.038, respectively). MALAT1 may be selected as an early detection biomarker for CRC. Furthermore, lincRNA-ROR and lincRNA-p21 may serve as prognostic and therapeutic biomarkers in patients with CRC.

LncRNA CCAT2 promotes angiogenesis in glioma through activation of VEGFA signalling by sponging miR-424

Glioma is characterized by high morbidity, high mortality and poor prognosis. Recent studies exhibited that lncRNA CCAT2 is overexpressed in glioma and promotes glioma progression, but the specific molecular biological mechanism remains to be determined. We performed qRT-PCR to evaluate the expression of related genes, Western blotting analysis to measure protein levels, colony formation assay to detect the proliferative ability of glioma cells, flow cytometry to measure cell apoptosis, bioinformatics analysis and dual luciferase assay to verify the binding sites and the targeted regulatory relationship in A172 and U251 cell lines and tube formation assay to determine endothelial angiogenesis. LncRNA CCAT2 and VEGFA were highly expressed, while miR-424 was expressed at low levels in NHA cells. Furthermore, knockdown of lncRNA CCAT2 decreased cell proliferation, increased cell apoptosis and inhibited endothelial angiogenesis in glioma. Moreover, lncRNA CCAT2 shared a complementary sequence with miR-424 which in turn directly bound to the 3'-UTR of VEGFA. Further investigation indicated that lncRNA CCAT2 promoted cell proliferation and endothelial angiogenesis by inducing the PI3K/AKT signalling pathway in glioma. The oncogenic lncRNA CCAT2 is highly associated with the development of glioma and exerts its function by upregulating VEGFA via miR-424.

Epigenetics of colorectal cancer: biomarker and therapeutic potential

Colorectal cancer (CRC), a leading cause of cancer-related death worldwide, evolves as a result of the stepwise accumulation of a series of genetic and epigenetic alterations in the normal colonic epithelium, leading to the development of colorectal adenomas and invasive adenocarcinomas. Although genetic alterations have a major role in a subset of CRCs, the pathophysiological contribution of epigenetic aberrations in this malignancy has attracted considerable attention. Data from the past couple of decades has unequivocally illustrated that epigenetic marks are important molecular hallmarks of cancer, as they occur very early in disease pathogenesis, involve virtually all key cancer-associated pathways and, most importantly, can be exploited as clinically relevant disease biomarkers for diagnosis, prognostication and prediction of treatment response. In this Review, we summarize the current knowledge on the best-studied epigenetic modifications in CRC, including DNA methylation and histone modifications, as well as the role of non-coding RNAs as epigenetic regulators. We focus on the emerging potential for the bench-to-bedside translation of some of these epigenetic alterations into clinical practice and discuss the burgeoning evidence supporting the potential of emerging epigenetic therapies in CRC as we usher in the era of precision medicine.

LncRNA, a novel target biomolecule, is involved in the progression of colorectal cancer

Colorectal cancer is one of the most commonly diagnosed malignancies among males and females worldwide. Although China is a country with a low incidence of colorectal cancer, with the improvement of China's economy and lifestyle changes, the incidence rate in China has generally increased in recent years, and the morbidity and mortality of colorectal cancer rank fifth among those of all malignant tumours. Furthermore, despite recent improvements in screening strategies and treatments for colorectal cancer, the prognosis of advanced colorectal cancer is still poor, mainly due to the recurrence or distant metastasis of this disease. Thus, colorectal cancer still seriously threatens the health and life of people and is a major public health problem worthy of further study. Recently, accumulating evidence has revealed that colorectal carcinogenesis might be a multistep process driven by progressive genetic abnormalities, including changes in lncRNA expression. Moreover, a large number of studies have discovered and studied the abnormal expression of lncRNAs in colorectal cancer, providing a promising target for the diagnosis and treatment of colorectal cancer, which will promote human understanding of the pathogenesis of colorectal cancer and improve diagnosis and treatment. Therefore, in the present review, we mainly summarize the present status of colorectal cancer, the characteristics, functions and clinical perspectives of lncRNAs, and the current therapeutic methods used for colorectal cancer, especially the application of lncRNAs in the treatment of colorectal cancer. It is hoped that this review will give readers a new understanding of the roles of lncRNAs in colorectal cancer.

Long Non-coding RNA ITIH4-AS1 Accelerates the Proliferation and Metastasis of Colorectal Cancer by Activating JAK/STAT3 Signaling

Accumulating evidence has uncovered long non-coding RNAs (lncRNAs) as central regulators in the pathogenesis of diverse human cancers including colorectal cancer (CRC). The present study discovered that a novel lncRNA ITIH4 antisense RNA 1 (ITHI4-AS1) was frequently under-expressed in most normal human tissues, including colon tissues. Therefore, we aimed to investigate the role of ITHI4-AS1 in CRC. Interestingly, a significant overexpression of ITIH4-AS1 was observed in CRC cell lines relative to normal NCM460 cells. Also, we investigated the facilitating role of ITIH4-AS1 in CRC cell growth and metastasis both in vitro and in vivo. Additionally, we explained that ITIH4-AS1 upregulation in CRC was attributed to downregulation or even depletion of RE1 silencing transcription factor (REST), a presently identified transcriptional repressor for ITIH4-AS1. Meanwhile, the contribution of ITIH4-AS1 to CRC development was validated to rely on the activation of the JAK/STAT3 pathway. More importantly, we verified that FUS interacted with both ITIH4-AS1 and STAT3, and that ITIH4-AS1 evoked nuclear translocation of phosphorylated (p)-STAT3 in CRC through recruiting FUS. In summary, our findings unveiled for the first time that REST downregulation-enhanced ITIH4-AS1 exerts pro-tumor functions in CRC through FUS-dependent activation of the JAK/STAT3 pathway, implying that targeting ITIH4-AS1 may be a novel effective strategy for CRC therapy.

The identification of CRNDE, H19, UCA1 and HOTAIR as the key lncRNAs involved in oxaliplatin or irinotecan resistance in the chemotherapy of colorectal cancer based on integrative bioinformatics analysis

With the increasing rate of chemoresistance in colorectal cancer (CRC) patients with advanced tumor stages, it is a matter of urgent importance to delineate the factors involved in the drug resistance process. In this study, gene expression profiles were downloaded from the Gene Expression Omnibus database and an integrated analysis with the aim of detecting hub long non‑coding RNAs (lncRNAs) and their regulated, differentially expressed genes (DEGs) during treatment with oxaliplatin (OxPt) or irinotecan was conducted. A total of seven differentially expressed lncRNAs were correlated with OxPt resistance and 21 were correlated with resistance to SN‑38, the active metabolite of irinotecan. Gene Ontology annotation and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis confirmed that drug resistance was strongly associated with an imbalance between cell proliferation and apoptosis, cell energetic metabolism under hypoxic conditions, and angiogenesis. Moreover, a large number of lncRNA‑targeted DEGs were located in extracellular exosomes. Further analyses identified four hub lncRNAs involved in the process of drug resistance, including CRNDE, H19, UCA1 and HOTAIR, which are predictive factors for treatment sensitivity. Among them, HOTAIR stands out as a strong factor, the elevated expression of which is also associated with advanced tumor node and metastasis stage and poor CRC disease prognosis.

Long non-coding RNA LINC01627 is a prognostic risk factor for epithelial ovarian cancer

Ovarian malignancies are commonly diagnosed cancers of the female reproductive system. Recent studies have revealed that long non-coding RNAs (lncRNAs) can regulate a variety of oncological processes. In the present study, ovarian cancer expression datasets were searched in the GEO database using the GPL570 platform. Differential lncRNA expression between normal ovarian tissues and ovarian tumors were analyzed using the R package 'limma', and patient prognosis was accessed using the package 'survival'. Four databases, GSE14001, GSE18520, GSE38666 and GSE40595, were used for the analysis. A total of 64 lncRNAs were highly expressed and 4 were downregulated within these four databases. Prognostic analysis of the 68 lncRNAs in the four databases was performed, and revealed that the expression of long intergenic non-protein coding RNA 1627 (LINC01627) was negatively associated with patient prognosis in GSE19829 and GSE62193; there was no association between LINC01627 expression and patient's prognosis in GSE18520 or GSE63885. To investigate the proposed association between LINC01627 and patient prognosis, meta-analysis revealed that the total hazard ratio was 1.38 and the 95% confidence interval was between 1.04 and 1.83. Subgroup analysis revealed that LINC01627 may predict patient prognosis in high-grade, advanced and serous epithelial ovarian cancer, which was a risk factor for prognosis. Further assessment was performed in clinical samples and ovarian cancer cells, where the knockdown of LINC01627 inhibited the proliferative and migratory capacities of HO8910 and HEY cells. Collectively, the present results suggested that lncRNA LINC01627 may serve an oncogenic role in the development of epithelial ovarian tumors.

Long non-coding RNA bladder cancer-associated transcript 2 contributes to disease progression, chemoresistance and poor survival of patients with colorectal cancer

Colorectal cancer (CRC) is one of the leading causes of cancer-associated mortality worldwide. Long non-coding RNAs (lncRNAs) have been revealed to modulate various biological cell processes, and are involved in the initiation and progression of different diseases, including CRC. However, the role of lncRNA bladder cancer-associated transcript 2 (BLACAT2) in CRC has not been defined. The present study aimed to investigate the role of BLACAT2 in CRC. The present study measured the expression levels of BLACAT2 in CRC cells and tissues by reverse-transcription-quantitative polymerase chain reaction, and associations among BLACAT2 expression levels, important clinicopathological parameters and patient survival were statistically evaluated. The functional role of BLACAT2 in metastasis, proliferation and drug resistance was also detected. BLACAT2 was overexpressed in CRC cells and tissues, and high BLACAT2 expression was associated with larger tumor size, and more advanced lymph node (N), metastasis (M) and tumor-NM stages. Additionally, survival analysis demonstrated that patients with high BLACAT2 expression exhibited poor overall survival. Notably, high BLACAT2 expression was identified as an independent risk factor for overall survival. Migration and invasion assays revealed that BLACAT2 promoted migration and invasion, respectively. In addition, overexpression of BLACAT2 increased colony numbers and optical density values of CRC cells in a colony formation assay and an MTT assay, respectively. Furthermore, BLACAT2 levels were significantly increased in 5-fluorouracil-resistant cells, and overexpression of BLACAT2 was markedly associated with a low cell inhibition rate. In conclusion, BLACAT2 overexpression may contribute to the metastasis, proliferation and chemoresistance of CRC cells, and high BLACAT2 expression may be a promising prognostic marker for patients with CRC.

Roles of long non-coding RNAs in colorectal cancer tumorigenesis: A Review

Long non-coding RNAs (lncRNAs) are newly identified potential biological and gene regulators. Similar to other cell-free circulating cancer-related nucleic acids, lncRNAs are released in the peripheral circulation of cancer patients and allow for non-invasive gene expression assessment. lncRNAs are considered to be promising biomarkers for cancer prognosis and diagnosis. Several lncRNAs have been found to regulate developmental processes in a number of biological disorders. Recent studies indicated that lncRNAs are associated with numerous diseases, most notably cancer, as they were found to be highly expressed or silenced in a number of human cancers, including colorectal cancer (CRC). Despite advances in the current detection methods, over half of cancer patients succumb to the disease, as several CRC cases are diagnosed at an advanced stage. Due to the lack of non-invasive and low-cost prognostic and diagnostic tests for CRC, the identification of novel, potentially effective biomarkers has been attracting increasing attention in recent cancer research. The present review focused on the most widely applied lncRNAs in cancer detection, including CRC, in vitro.

The targeting of non‑coding RNAs by curcumin: Facts and hopes for cancer therapy (Review)

Curcumin [(1E,6E)-1,7-bis(4-hydroxy-3-methoxyphenyl) hepta-1,6-diene-3,5-dione] is a natural polyphenol that is derived from the turmeric plant (curcuma longa L.). Curcumin is widely used in food coloring, preservatives, and condiments. Curcumin possesses anti-tumor, anti-oxidative and anti-inflammatory efficacy, as well as other pharmacological effects. Emerging evidence indicates that curcumin alters microRNAs (miRNAs) and long non-coding RNAs (lncRNAs) in various types of cancers. Both miRNAs and lncRNAs are non-coding RNAs that can epigenetically modulate the expression of multiple genes via post-transcriptional regulation. In the present review, the interactions between curcumin and non-coding RNAs are summarized in numerous types of cancers, including lung, colorectal, prostate, breast, nasopharyngeal, pancreatic, blood, and ovarian cancer, and the vital non-coding RNAs and their downstream targets are described.

SNHG15 is a bifunctional MYC-regulated noncoding locus encoding a lncRNA that promotes cell proliferation, invasion and drug resistance in colorectal cancer by interacting with AIF

Background

Thousands of long noncoding RNAs (lncRNAs) are aberrantly expressed in various types of cancers, however our understanding of their role in the disease is still very limited.

Methods

We applied RNAseq analysis from patient-derived data with validation in independent cohort of patients. We followed these studies with gene regulation analysis as well as experimental dissection of the role of the identified lncRNA by multiple in vitro and in vivo methods.

Results

We analyzed RNA-seq data from tumors of 456 CRC patients compared to normal samples, and identified SNHG15 as a potentially oncogenic lncRNA that encodes a snoRNA in one of its introns. The processed SNHG15 is overexpressed in CRC tumors and its expression is highly correlated with poor survival of patients. Interestingly, SNHG15 is more highly expressed in tumors with high levels of MYC expression, while MYC protein binds to two E-box motifs on SNHG15 sequence, indicating that SNHG15 transcription is directly regulated by the oncogene MYC.

The depletion of SNHG15 by siRNA or CRISPR-Cas9 inhibits cell proliferation and invasion, decreases colony formation as well as the tumorigenic capacity of CRC cells, whereas its overexpression leads to opposite effects. Gene expression analysis performed upon SNHG15 inhibition showed changes in multiple relevant genes implicated in cancer progression, including MYC, NRAS, BAG3 or ERBB3. Several of these genes are functionally related to AIF, a protein that we found to specifically interact with SNHG15, suggesting that the SNHG15 acts, at least in part, by regulating the activity of AIF. Interestingly, ROS levels, which are directly regulated by AIF, show a significant reduction in SNHG15-depleted cells. Moreover, knockdown of SNHG15 increases the sensitiveness of the cells to 5-FU, while its overexpression renders them more resistant to the chemotherapeutic drug.

Conclusion

Altogether, these results describe an important role of SNHG15 in promoting colon cancer and mediating drug resistance, suggesting its potential as prognostic marker and target for RNA-based therapies.

Electronic supplementary material

The online version of this article (10.1186/s13046-019-1169-0) contains supplementary material, which is available to authorized users.

LncRNA ZEB1-AS1 reduces liver cancer cell proliferation by targeting miR-365a-3p

Liver carcinoma is one of the most common malignancies worldwide. Previous studies have demonstrated that long non-coding RNAs (lncRNAs) are crucial mediators that participate in a wide range of molecular processes associated with carcinogenesis. However, little is known about the specific mechanisms that underlie the majority of lncRNAs. Many studies have indicated that lncRNAs affect microRNA (miRNA or miR) activities via physical base-paired binding, therefore serving as competing endogenous RNAs (ceRNAs) that indirectly regulate the expression of miRNA targets. In the current study, it was revealed that lncRNA zinc-finger E-box binding homeobox 1 antisense 1 (ZEB1-AS1) serves as a ceRNA for miR-365a-3p, functioning to positively modulate E2F transcription factor 2 (E2F2) expression in liver cancer cells. Additionally, reverse transcription-quantitative polymerase chain reaction demonstrated that levels of ZEB1-AS1 were abnormally upregulated in liver cancer and this was positively correlated with E2F2 expression. Furthermore, high levels of ZEB1-AS1 exhibited a trend for poor survival in patients with liver cancer. Western blot analysis demonstrated that ZEB1-AS1 silencing could reduce E2F2 expression. EdU staining and flow cytometry analysis indicated that downregulation of ZEB1-AS1 could suppress cell proliferation and decrease the S phase proportion of liver cancer cells, which was effectively reversed by the inhibition of miR-365a-3p. ZEB1-AS1 was also determined to be physically associated with miR-365a-3p, while miR-365a-3p was revealed to target the E2F2 3′UTR for degradation or translational repression. The results also demonstrated that ZEB1-AS1 positively regulates E2F2 expression by competitively binding to miR-365a-3p. It was further revealed to enhance liver cancer cell proliferation. Thus, these results indicate that ZEB1-AS1 is required for liver cancer progression in a ceRNA dependent manner. ZEB1-AS1 may therefore be a potential target for liver cancer intervention.

Prognostic and Clinicopathological Significance of lncRNA MVIH in Cancer Patients

Objectives: LncRNA associated with microvascular invasion in hepatocellular carcinoma (lncRNA MVIH) is a newly discovered long non-coding RNA that aberrantly up-regulates and holds prognostic value in various tumors. The aim of the review and meta-analysis is to assess its prognostic potential and functions in malignant tumors.

Materials and methods: PubMed, PMC, EMBASE, Web of Science, Cochrane Library, China National Knowledge Infrastructure (CNKI), and Wanfang Database were carefully searched for articles published as of Jan. 1, 2018. Hazard ratios (HRs) or odds ratios (ORs) with 95% confidence intervals (95% CIs) were calculated to demonstrate prognostic value of lncRNA MVIH using Stata 12.0 software.

Results: Six original studies including 830 cancer patients were ultimately enrolled in this meta-analysis. The pooled results showed that elevated lncRNA MVIH expression was significantly correlated with unfavorable OS (HR=2.17, 95% CI: 1.58-2.76, p < 0.001) and RFS/DFS/PFS (HR=2.21, 95% CI: 1.54-2.87, p < 0.001) in cancer patients. Additionally, high expression of lncRNA MVIH was related to positive lymph node metastasis (OR = 3.04, 95% CI: 1.37-6.75, p = 0.006) and advanced clinical stage (OR = 2.52, 95% CI: 1.68-3.79, p < 0.001).

Conclusions: LncRNA MVIH over-expression was associated with poor clinical outcomes in multiple cancer types. More studies are warranted to verify and strengthen the clinical value of lncRNA MVIH in human cancers.

Impact of the gut microbiome on the genome and epigenome of colon epithelial cells: contributions to colorectal cancer development

In recent years, the number of studies investigating the impact of the gut microbiome in colorectal cancer (CRC) has risen sharply. As a result, we now know that various microbes (and microbial communities) are found more frequently in the stool and mucosa of individuals with CRC than healthy controls, including in the primary tumors themselves, and even in distant metastases. We also know that these microbes induce tumors in various mouse models, but we know little about how they impact colon epithelial cells (CECs) directly, or about how these interactions might lead to modifications at the genetic and epigenetic levels that trigger and propagate tumor growth. Rates of CRC are increasing in younger individuals, and CRC remains the second most frequent cause of cancer-related deaths globally. Hence, a more in-depth understanding of the role that gut microbes play in CRC is needed. Here, we review recent advances in understanding the impact of gut microbes on the genome and epigenome of CECs, as it relates to CRC. Overall, numerous studies in the past few years have definitively shown that gut microbes exert distinct impacts on DNA damage, DNA methylation, chromatin structure and non-coding RNA expression in CECs. Some of the genes and pathways that are altered by gut microbes relate to CRC development, particularly those involved in cell proliferation and WNT signaling. We need to implement more standardized analysis strategies, collate data from multiple studies, and utilize CRC mouse models to better assess these effects, understand their functional relevance, and leverage this information to improve patient care.

Long noncoding RNA GIHCG induces cancer progression and chemoresistance and indicates poor prognosis in colorectal cancer

Background

Colorectal cancer (CRC) is one of the leading causes of cancer-related death worldwide, however, the mechanisms of CRC progression remain obscure. The present study investigated the clinical significance and functional role of long noncoding RNA (lncRNA) GIHCG in CRC.

Methods

Expression of GIHCG was detected by quantitative real time polymerase chain reaction (qRT-PCR) in seven CRC cell lines and 110 CRC tissues. Comparison of clinicopathological characteristics in the high GIHCG expression group and the low GIHCG expression group was performed. The overall survival (OS) and progression-free survival (PFS) of the patients were depicted with Kaplan-Meier test and compared with Log-rank test. Univariate and multivariate analyses were carried out to detect the risk factors for poor OS and PFS. In addition, expression of GIHCG was silenced with siRNAs in LoVo cells and overexpressed with pcDNA3.1-GIHCG vector in SW480 cells, respectively. And the Transwell assay, Matrigel assay, colony formation assay and Cell Counting Kit-8 assay (CCK-8) were performed to investigate the role of GIHCG in the migration, invasion and proliferation of CRC cells. Besides, the role of GIHCG in chemoresistance was also detected.

Results

GIHCG was overexpressed in seven CRC cell lines and 110 CRC tissues. High GIHCG expression was correlated with lymphovascular invasion, lymph node metastasis, distant metastasis and advanced TNM stages. Moreover, patients with high GIHCG expression had much poorer OS and PFS rates. Besides, high GIHCG expression was identified as an independent risk factor for poor OS and PFS. The Transwell assay and the Matrigel assay discovered that GIHCG deficiency inhibited cell migration and invasion, while ectopic expression of GIHCG promoted migration and invasion. Besides, the colony formation assay and the CCK-8 assay verified that GIHCG increased cell proliferation ability. By establishing 5-fluorouracil (5-FU) and Oxaliplatin (Oxa)-resistant LoVo cells and SW480 cells, we found chemoresistant CRC cells had much higher expression levels of GIHCG. Also, GIHCG facilitated cell survival under 5-FU or Oxa treatment. Furthermore, silencing of GIHCG notably reduced the improved cell survival rates of 5-FU or Oxa-resistant LoVo cells compared with control cells.

Conclusion

GIHCG contributes to cancer progression and chemoresistance and indicates poor prognosis in CRC. GIHCG may be a promising prognostic biomarker and therapeutic target in CRC.

Autophagy-Modulating Long Non-coding RNAs (LncRNAs) and Their Molecular Events in Cancer

Cancer is a global threat of health. Cancer incidence and death is also increasing continuously because of poor understanding of diseases. Although, traditional treatments (surgery, radiotherapy, and chemotherapy) are effective against primary tumors, death rate is increasing because of metastasis development where traditional treatments have failed. Autophagy is a conserved regulatory process of eliminating proteins and damaged organelles. Numerous research revealed that autophagy has dual sword mechanisms including cancer progressions and suppressions. In most of the cases, it maintains homeostasis of cancer microenvironment by providing nutritional supplement under starvation and hypoxic conditions. Over the past few decades, stunning research evidence disclosed significant roles of long non-coding RNAs (lncRNAs) in the regulation of autophagy. LncRNAs are RNA containing more than 200 nucleotides, which have no protein-coding ability but they are found to be expressed in most of the cancers. It is also proved that, autophagy-modulating lncRNAs have significant impacts on pro-survival or pro-death roles in cancers. In this review, we highlighted the recently identified autophagy-modulating lncRNAs, their signaling transduction in cancer and mechanism in cancer. This review will explore newly emerging knowledge of cancer genetics and it may provide novel targets for cancer therapy.

A novel long noncoding RNA, LINC00483 promotes proliferation and metastasis via modulating of FMNL2 in CRC

Long non-coding RNAs (lncRNAs) are extensively involved in multiple malignancies including colorectal cancer (CRC). In the present study, we found a novel lncRNA, long intergenic non-protein coding RNA 483 (LINC00483), which was upregulated in CRC. We also illustrated that upregulated LINC00483 was correlated with poor clinicopathological features of patients with CRC. Functionally, we displayed that a knockdown of LINC00483 suppressed LOVO and HT29 cells proliferation and metastatic ability. We further illustrated that miR-204-3p was involved in LINC00483 induced proliferation and metastasis. An overexpression of miR-204-3p could attenuate the facilitative effect which LINC00483 presented. Through a luciferase assay, we showed the direct binding effect between LINC00483 and miR-204-3p. Even further, we revealed that LINC00483 and formin like 2 (FMNL2) shared a similar miR-204-3p response elements (MREs-204-3p). FMNL2 was a direct target of miR-204-3p. FMNL2 was a downstream gene of LINC00483 and participated in LINC00483 mediated proliferation and metastasis. Lastly, we proved that LINC00483 promoted proliferation and metastasis via modulating of FMNL2 in LOVO and HT29 cells. In summary, the outcomes of this study illustrated that LINC00483 promoted CRC cells proliferation and metastasis via modulating of FMNL2 by acting as a ceRNA of miR-204-3p. LINC00483/miR-204-3p/FMNL2 axial might be a novel target in molecular treatment of CRC.

The lncRNA RMEL3 protects immortalized cells from serum withdrawal-induced growth arrest and promotes melanoma cell proliferation and tumor growth

RMEL3 is a recently identified lncRNA associated with BRAFV600E mutation and melanoma cell survival. Here, we demonstrate strong and moderate RMEL3 upregulation in BRAF and NRAS mutant melanoma cells, respectively, compared to melanocytes. High expression is also more frequent in cutaneous than in acral/mucosal melanomas, and analysis of an ICGC melanoma dataset showed that mutations in RMEL3 locus are preponderantly C > T substitutions at dipyrimidine sites including CC > TT, typical of UV signature. RMEL3 mutation does not correlate with RMEL3 levels, but does with poor patient survival, in TCGA melanoma dataset. Accordingly, RMEL3 lncRNA levels were significantly reduced in BRAFV600E melanoma cells upon treatment with BRAF or MEK inhibitors, supporting the notion that BRAF-MEK-ERK pathway plays a role to activate RMEL3 gene transcription. RMEL3 overexpression, in immortalized fibroblasts and melanoma cells, increased proliferation and survival under serum starvation, clonogenic ability, and xenografted melanoma tumor growth. Although future studies will be needed to elucidate the mechanistic activities of RMEL3, our data demonstrate that its overexpression bypasses the need of mitogen activation to sustain proliferation/survival of non-transformed cells and suggest an oncogenic role for RMEL3.