Long non-coding RNA HOXD-AS1 in cancer

HAGLR, A Long Non-coding RNA of Potential Tumor Suppressive Function in Clear Cell Renal Cell Carcinoma: Diagnostic and Prognostic Implications

Research works suggested the role of long non-coding RNAs (lncRNAs) in pathogenesis of clear cell renal cell carcinoma (ccRCC). lncRNA HAGLR is studied in several malignancies, but not in ccRCC. From The Cancer Genome Atlas Kidney Renal Clear Cell Carcinoma (TCGA-KIRC) dataset, we analyzed molecular alterations of HAGLR and constructed a competitive endogenous RNA (ceRNA) network with related miRNAs and mRNAs. Gene Ontology analysis was done to identify important pathways enriched with HAGLR recovered mRNAs. Clinical importance of HAGLR and related mRNAs was assessed and, the impact of selected mRNA-encoding genes on tumor immune infiltration was studied using TIMER. HAGLR expression was reduced in ccRCC than in normal kidneys, and correlated significantly with gene promoter methylation. Low HAGLR level in tumors showed diagnostic potency, and was associated with clinicopathological parameters (stage/grade/metastasis) and poor patient survival. The HAGLR-associated ceRNA network constituted 13 miRNAs and 23 mRNAs differentially expressed in the TCGA-KIRC dataset. From HAGLR recovered mRNA-encoding genes, we developed a 5-gene (PAQR5, ARHGAP24, HABP4, PDLIM5, and RPS6KA2) prognostic signature in the training dataset and validated it in testing as well as entire datasets. The expression level of signature genes showed negative correlation with tumor infiltration of immune cells having adverse impact on ccRCC prognosis and also with tumor derived chemokines facilitating the infiltration. In conclusion, HAGLR seemed to play a tumor suppressive role in ccRCC. HAGLR and associated gene signature may have implementation in improving existing prognostic measure and developing effective immunotherapeutic strategies for ccRCC.

Crosstalk between Long Non-Coding RNA and Spliceosomal microRNA as a Novel Biomarker for Cancer

Non-coding RNAs (ncRNAs) play diverse roles in regulating cellular processes and have been implicated in pathological conditions, including cancer, where interactions between ncRNAs play a role. Relevant here are (i) microRNAs (miRNAs), mainly known as negative regulators of gene expression in the cytoplasm. However, identification of miRNAs in the nucleus suggested novel nuclear functions, and (ii) long non-coding RNA (lncRNA) regulates gene expression at multiple levels. The recent findings of miRNA in supraspliceosomes of human breast and cervical cancer cells revealed new candidates of lncRNA targets. Here, we highlight potential cases of crosstalk between lncRNA and supraspliceosomal miRNA expressed from the same genomic region, having complementary sequences. Through RNA:RNA base pairing, changes in the level of one partner (either miRNA or lncRNA), as occur in cancer, could affect the level of the other, which might be involved in breast and cervical cancer. An example is spliceosomal mir-7704 as a negative regulator of the oncogenic lncRNA HAGLR. Because the expression of spliceosomal miRNA is cell-type-specific, the list of cis-interacting lncRNA:spliceosomal miRNA presented here is likely just the tip of the iceberg, and such interactions are likely relevant to additional cancers. We thus highlight the potential of lncRNA:spliceosomal miRNA interactions as novel targets for cancer diagnosis and therapies.

FUT8-AS1/miR-944/Fused in Sarcoma/Transcription Factor 4 Feedback Loop Participates in the Development of Oral Squamous Cell Carcinoma through Activation of Wnt/β-Catenin Signaling Pathway

As a common type of head and neck squamous cell carcinoma, oral squamous cell carcinoma (OSCC) is a lethal and deforming disease. Long noncoding RNAs have emerged as critical modulators in different malignancies. However, the role of fucosyltransferase 8 antisense RNA 1 (FUT8-AS1) in OSCC still remains elusive. In this study, quantitative RT-PCR and Western blot were used for the measurement of RNAs and proteins. Mechanism assays explored the putative correlation among genes. In vitro assays evaluated the changes in OSCC cell malignant phenotype, whereas in vivo assays highlighted the influence of FUT8-AS1 on tumor growth. FUT8-AS1, aberrantly up-regulated in OSCC tissues and cells, could exacerbate OSCC cell malignant behaviors. The cancerogenic property of FUT8-AS1 in OSCC was further confirmed via animal experiments. Furthermore, FUT8-AS1 enhanced the expression of transcription factor 4 (TCF4) via sponging miR-944 and recruiting fused in sarcoma (FUS), thus affecting OSCC cell biological behaviors via modulation on Wnt/β-catenin signaling activity. In addition, TCF4 was validated as the transcriptional activator of FUT8-AS1. To conclude, TCF4-mediated FUT8-AS1 could exacerbate OSCC cell malignant behaviors and facilitate tumor growth via modulation on miR-944/FUS/TCF4.

HOX cluster-embedded lncRNAs and epithelial-mesenchymal transition in cancer: Molecular mechanisms and therapeutic opportunities

Although there has been substantial improvement in the treatment modalities, cancer remains the major cause of fatality worldwide. Metastasis, recurrence, and resistance to oncological therapies are the leading causes of cancer mortality. Epithelial-mesenchymal transition (EMT) is a complex biological process that allows cancer cells to undergo morphological transformation into a mesenchymal phenotype to acquire invasive potential. It encompasses reversible and dynamic ontogenesis by neoplastic cells during metastatic dissemination. Hence, understanding the molecular landscape of EMT is imperative to identify a reliable clinical biomarker to combat metastatic spread. Accumulating evidence reveals the role of HOX (homeobox) cluster-embedded long non-coding RNAs (lncRNAs) in EMT and cancer metastasis. They play a crucial role in the induction of EMT, modulating diverse biological targets. The present review emphasizes the involvement of HOX cluster-embedded lncRNAs in EMT as a molecular sponge, chromatin remodeler, signaling regulator, and immune system modulator. Furthermore, the molecular mechanisms behind therapy resistance and the potential use of novel drugs targeting HOX cluster-embedded lncRNAs in the clinical management of distant metastasis will be discussed.

Discovery and Validation of a Novel Metastasis-Related lncRNA Prognostic Signature for Colorectal Cancer

Background: Cancer metastasis-related chemoresistance and tumour progression are the leading causes of death among CRC patients. Therefore, it is urgent to identify reliable novel biomarkers for predicting the metastasis of CRC.

Methods: The gene expression and corresponding clinical data of CRC patients were downloaded from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases. Univariate and multivariate analyses were performed to identify prognostic metastasis-related lncRNAs. Nomograms were constructed, and the predictive accuracy of the nomogram model was assessed by ROC curve analysis. Then, the R package “pRRophetic” was used to predict chemotherapeutic response in CRC patients. In addition, the CIBERSORT database was introduced to evaluate tumour infiltrating immune cells between the high—and low-risk groups. The potential roles of SNHG7 and ZEB1-AS1 in CRC cell lines were further confirmed by in vitro experiments.

Results: An 8-lncRNA (LINC00261, RP1-170O19.17, CAPN10-AS1, SNHG7, ZEB1-AS1, U47924.27, NIFK-AS1, and LINC00925) signature was constructed for CRC prognosis prediction, which stratified patients into two risk groups. Kaplan-Meier analysis revealed that patients in the higher-risk group had a lower survival probability than those in the lower-risk group [p < 0.001 (TCGA); P = 0.044 (GSE39582); and P = 0.0078 (GSE29621)] The AUCs of 1-, 3-, and 5-year survival were 0.678, 0.669, and 0.72 in TCGA; 0.58, 0.55, and 0.56 in GSE39582; and 0.75, 0.54, and 0.56 in GSE29621, respectively. In addition, the risk score was an independent risk factor for CRC patients. Nomograms were constructed, and the predictive accuracy was assessed by ROC curve analysis. This signature could effectively predict the immune status and chemotherapy response in CRC patients. Moreover, SNHG7 and ZEB1-AS1 depletion significantly suppressed the colony formation, migration, and invasion of CRC cells in vitro.

Conclusion: We constructed a signature that could predict the metastasis of CRC and provide certain theoretical guidance for novel therapeutic approaches for CRC.

A Novel Risk Model Based on Autophagy-Related LncRNAs Predicts Prognosis and Indicates Immune Infiltration Landscape of Patients With Cutaneous Melanoma

Cutaneous melanoma (CM) is a malignant tumor with a high incidence rate and poor prognosis. Autophagy plays an essential role in the development of CM; however, the role of autophagy-related long noncoding RNAs (lncRNAs) in this process remains unknown. Human autophagy-related genes were extracted from the Human Autophagy Gene Database and screened for autophagy-related lncRNAs using Pearson correlation. Multivariate Cox regression analysis was implemented to identify ten autophagy-related lncRNAs associated with prognosis, and a risk model was constructed. The Kaplan-Meier survival curve showed that the survival probability of the high-risk group was lower than that of the low-risk group. A novel predictive model was constructed to investigate the independent prognostic value of the risk model. The nomogram results showed that the risk score was an independent prognostic signature that distinguished it from other clinical characteristics. The immune infiltration landscape of the low-risk and high-risk groups was further investigated. The low-risk groups displayed higher immune, stromal, and ESTIMATE scores and lower tumor purity. The CIBERSORT and single sample gene set enrichment analysis (ssGSEA) algorithms indicated a notable gap in immune cells between the low- and high-risk groups. Ten autophagy-related lncRNAs were significantly correlated with immune cells. Finally, Gene Set Enrichment Analysis (GSEA) and Gene Set Variation Analysis (GSVA) results demonstrated that autophagy-related lncRNA-mediated and immune-related signaling pathways are crucial factors in regulating CM. Altogether, these data suggest that constructing a risk model based on ten autophagy-related lncRNAs can accurately predict prognosis and indicate the tumor microenvironment of patients with CM. Thus, our study provides a new perspective for the future clinical treatment of CM.

LncRNA HOXD-AS1 affects proliferation and apoptosis of cervical cancer cells by promoting FRRS1 expression via transcription factor ELF1

To investigate the function of lncRNA HOXD-AS1 in cervical squamous cell carcinoma (CESC) and the underlying mechanism. The expressions of HOXD-AS1 and FRRS1 were analyzed on the online software GEPIA based on CESC-related information in The Cancer Genome Atlas (TCGA). Cervical cancer cells (SiHa and Hela) were accordingly transfected with pCDNA3.1-HOXD-AS1, sh-HOXD-AS1, sh-FRRS1 or pCDNA3.1-ELF1. After cell transfection, CCK-8, EDU and flow cytometry were applied for measurement of cell vitality, quantity and apoptosis, respectively. The relationship between HOXD-AS1 and FRRS1 was predicted on the online software LncMap and further verified by RNA binding protein immunoprecipitation. Nude mice were injected with stabilized SiHa cells transfected with sh-HOXD-AS1 to assess the tumorigenic ability of HOXD-AS1 in vivo. Immunohistochemistry detected the expression of the proliferation marker Ki-67. The levels of HOXD-AS1, ELF1 and FRRS1 were measured in vivo and in vitro. HOXD-AS1 and FRRS1 were overexpressed in CESC. After transfection of sh-HOXD-AS1, sh-ELF1 or sh-FRRS1, the proliferation of SiHa and Hela cells was inhibited and their apoptosis was promoted; while HOXD-AS1 overexpression had opposite effects on CESC development. Co-transfection of sh-FRRS1 and pCDNA3.1-HOXD-AS1 could abolish the tumor suppressive effect of FRRS1 knockdown. HOXD-AS1 elevated the level of FRRS1 by binding ELF1. Furthermore, HOXD-AS1 contributed to the CESC growth in mouse models. HOXD-AS1 promotes CESC by up-regulating FRRS1 via ELF1.

A Signature of 14 Long Non-Coding RNAs (lncRNAs) as a Step towards Precision Diagnosis for NSCLC

LncRNAs have arisen as new players in the world of non-coding RNA. Disrupted expression of these molecules can be tightly linked to the onset, promotion and progression of cancer. The present study estimated the usefulness of 14 lncRNAs (HAGLR, ADAMTS9-AS2, LINC00261, MCM3AP-AS1, TP53TG1, C14orf132, LINC00968, LINC00312, TP73-AS1, LOC344887, LINC00673, SOX2-OT, AFAP1-AS1, LOC730101) for early detection of non-small-cell lung cancer (NSCLC). The total RNA was isolated from paired fresh-frozen cancerous and noncancerous lung tissue from 92 NSCLC patients diagnosed with either adenocarcinoma (LUAD) or lung squamous cell carcinoma (LUSC). The expression level of lncRNAs was evaluated by a quantitative real-time PCR (qPCR). Based on Ct and delta Ct values, logistic regression and gradient boosting decision tree classifiers were built. The latter is a novel, advanced machine learning algorithm with great potential in medical science. The established predictive models showed that a set of 14 lncRNAs accurately discriminates cancerous from noncancerous lung tissues (AUC value of 0.98 ± 0.01) and NSCLC subtypes (AUC value of 0.84 ± 0.09), although the expression of a few molecules was statistically insignificant (SOX2-OT, AFAP1-AS1 and LOC730101 for tumor vs. normal tissue; and TP53TG1, C14orf132, LINC00968 and LOC730101 for LUAD vs. LUSC). However for subtypes discrimination, the simplified logistic regression model based on the four variables (delta Ct AFAP1-AS1, Ct SOX2-OT, Ct LINC00261, and delta Ct LINC00673) had even stronger diagnostic potential than the original one (AUC value of 0.88 ± 0.07). Our results demonstrate that the 14 lncRNA signature can be an auxiliary tool to endorse and complement the histological diagnosis of non-small-cell lung cancer.

Transcriptome sequencing reveals a lncRNA-mRNA interaction network in extramammary Paget's disease

Background

Extramammary Paget’s disease (EMPD) is a rare malignant intraepidermal adenocarcinoma that is poorly understood. Regulatory long noncoding RNAs (lncRNAs) are characterized in many species and shown to be involved in processes such as development and pathologies, revealing a new layer of regulation in different diseases, especially in cancer studies. In the present study, we used high-throughput sequencing to reveal the lncRNA–mRNA interaction network in extramammary Paget’s disease.

Methods

High-throughput sequencing was used to identify differentially expressed lncRNA and mRNA profiles between EMPD patients and healthy controls. Then, a series of bioinformatics analyses were conducted to construct the lncRNA–mRNA interaction network, which was finally confirmed in vitro.

Results

Six pairs of EMPD tumor and normal skin samples were collected and sequenced to identify the differentially expressed lncRNA and mRNA profiles between EMPD and healthy controls. A total of 997 differentially expressed mRNAs and 785 differentially expressed lncRNAs were identified. The GO and KEGG analyses show that epidermal development and cell adhesion play important roles in EMPD. The results of the lncRNA–mRNA interaction network analysis suggested that NEAT1, PGAP1, FKBP5 and CDON were the pivotal nodes of the network and that lncRNA NEAT1 might regulate mRNA PGAP1, FKBP5 and CDON. The results of the quantitative real-time RT–PCR performed in ten other patients for NEAT1, PGAP1, FKBP5 and CDON were consistent with those of the sequencing analysis. Moreover, an in vitro experiment confirmed the interactions between NEAT1 and PGAP1, FKBP5 and CDON in human immortalized keratinocytes.

Conclusion

These findings suggest that the lncRNA–mRNA interaction network based on four pivotal nodes, NEAT1, PGAP1 FKBP5 and CDON, may play an important role in EMPD, which will contribute to a deeper understanding of the pathogenesis of EMPD.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12920-021-01135-2.

HOX cluster and their cofactors showed an altered expression pattern in eutopic and ectopic endometriosis tissues

Endometriosis is major gynecological disease that affects over 10% of women worldwide and 30%-50% of these women have pelvic pain, abnormal uterine bleeding and infertility. The cause of endometriosis is unknown and there is no definite cure mainly because of our limited knowledge about its pathophysiology at the cellular and molecular levels. Therefore, demystifying the molecular mechanisms that underlie endometriosis is essential to develop advanced therapies for this disease. In this regard, HOX genes are remarkable because of their critical role in endometrial development and receptivity during implantation, which is attributed to their ability to mediate some of the sex steroid functions during the reproductive period. Access to the expression profiles of these genes would provide the necessary information to uncover new genes for endometriosis and assist with disease diagnosis and treatment. In this study we demonstrate an altered expression pattern for the HOX clusters (A-D) and their cofactors in both eutopic and ectopic conditions compared to control tissue biopsies. Remarkably, most of the intensive changes occurred in eutopic samples from endometriosis patients compared to control tissue biopsies. Pathway analysis revealed the involvement of differentially expressed genes in cancer that correlate with an association between endometriosis and cancer. Our results suggest critical roles for the HOX cluster and their cofactors in endometriosis pathophysiology.

There and Back Again: Hox Clusters Use Both DNA Strands

Bilaterian animals operate the clusters of Hox genes through a rich repertoire of diverse mechanisms. In this review, we will summarize and analyze the accumulated data concerning long non-coding RNAs (lncRNAs) that are transcribed from sense (coding) DNA strands of Hox clusters. It was shown that antisense regulatory RNAs control the work of Hox genes in cis and trans, participate in the establishment and maintenance of the epigenetic code of Hox loci, and can even serve as a source of regulatory peptides that switch cellular energetic metabolism. Moreover, these molecules can be considered as a force that consolidates the cluster into a single whole. We will discuss the examples of antisense transcription of Hox genes in well-studied systems (cell cultures, morphogenesis of vertebrates) and bear upon some interesting examples of antisense Hox RNAs in non-model Protostomia.

IGF2BP2 knockdown suppresses thyroid cancer progression by reducing the expression of long non-coding RNA HAGLR

BACKGROUND

N6-methyladenosine (m6A), a common internal modification on RNAs, has been found to be closely linked with RNA biosynthesis/metabolism and cancer development. In this text, the roles and molecular mechanisms of m6A-bind protein IGF2BP2 in the development of thyroid cancer (TC) were investigated in vitro.

METHODS

IGF2BP2 and lncRNA HAGLR were screened out through multiple public databases such as TCGA, Ualcan, POSTAR2, Starbase, and GEPIA. Cell proliferative, migratory and invasive abilities were assessed by CCK-8, Transwell migration and invasion assays, respectively. Cell cycle distribution and cell apoptotic patterns were measured by flow cytometry. The interaction between HAGLR and IGF2BP2 was examined by RIP, RNA pull-down and luciferase assays and bioinformatics analysis. The effect of IGF2BP2 knockdown on the m6A level of HAGLR was explored by meRIP assay.

RESULTS

IGF2BP2 was highly expressed in TC tumor tissues. IGF2BP2 knockdown weakened cell proliferative, migratory, and invasive abilities, and induced cell cycle arrest and cell apoptosis in TC cells. LncRNA HAGLR expression was markedly upregulated and positively associated with IGF2BP2 expression in TC tissues. IGF2BP2 knockdown reduced HAGLR expression and transcript stability in TC cells. IGF2BP2 regulated HAGLR expression in an m6A-dependent manner. HAGLR overexpression weakened the effects of IGF2BP2 loss on cell proliferation, migration, invasion, apoptosis, and cell cycle progression in TC cells.

CONCLUSION

IGF2BP2 loss inhibited cell proliferation, migration and invasion, and induced cell apoptosis and cell cycle arrest by down-regulating HAGLR expression in an m6A-dependent manner in TC cells, providing some potential diagnostic and therapeutic targets for TC.

LncRNA MSC-AS1 motivates the development of melanoma by binding to miR-302a-3p and recruiting IGF2BP2 to elevate LEF1 expression

Melanoma is considered as the most common malignancy among skin cancers. The roles of many long non-coding RNAs (lncRNAs) have been clearly identified in multiple tumors. Nevertheless, lncRNA MSC antisense RNA 1 (MSC-AS1) has not been deeply investigated melanoma. In the present study, RT-qPCR and western blot analyses were used to measure the expression of RNAs and proteins. Functional and in vivo assays were implemented to detect the function of genes in melanoma. RNA pull-down, RIP and luciferase reporter assays were applied for determining interactions between RNA and protein molecules. It was observed that MSC-AS1 and lymphoid enhancer-binding factor 1 (LEF1) were remarkably up-regulated while microRNA-302a-3p (miR-302a-3p) down-regulated in melanoma cell lines. The silencing of MSC-AS1 hindered cell proliferation, migration and epithelial-mesenchymal transition (EMT) in vitro and tumor growth in vivo. Furthermore, MSC-AS1 regulated LEF1 expression through sponging miR-302a-3p and recruiting insulin like growth factor 2 mRNA-binding protein 2 (IGF2BP2). Eventually, LEF1 overexpression rescued cell progression impaired by MSC-AS1 knock-down. In summary, our research identified the MSC-AS1/miR-302a-3p/IGF2BP2/LEF1 axis in melanoma development, which indicated that MSC-AS1 is a potential biomarker in the treatment of melanoma.

Long Non-coding RNAs in Cisplatin Resistance in Osteosarcoma

OPINION STATEMENT

Osteosarcoma (OS), the most common primary malignant bone tumor, is a vastly aggressive disease in children and adolescents. Although dramatic progress in therapeutic strategies have achieved over the past several decades, the outcome remains poor for most patients with metastatic or recurrent OS. Nowadays, conventional treatment for OS patients is surgery combined with multidrug chemotherapy including doxorubicin, methotrexate, and cisplatin (CDDP). In this sense, cisplatin (CDDP) is one of the most drugs used in the treatment of OS but drug resistance to CDDP appears as a serious problem in the use of this drug in the treatment of OS. Thus, we consider that the understanding the molecular mechanisms and the genes involved that lead to CDDP resistance is essential to developing more effective treatments against OS. In this review, we present an outline of the key role of the long non-coding RNAs (lncRNAs) in CDDP resistance in OS. This overview is expected to contribute to understand the mechanisms of CDDP resistance in OS and the relationship of the expression regulation of several lncRNAs.

Roles and Mechanisms of the Long Noncoding RNAs in Cervical Cancer

Cervical cancer (CC) continues to be one of the leading causes of death for women across the world. Although it has been determined that papillomavirus infection is one of the main causes of the etiology of the disease, genetic and epigenetic factors are also required for its progression. Among the epigenetic factors are included the long noncoding RNAs (lncRNAs), transcripts of more than 200 nucleotides (nt) that generally do not code for proteins and have been associated with diverse functions such as the regulation of transcription, translation, RNA metabolism, as well as stem cell maintenance and differentiation, cell autophagy and apoptosis. Recently, studies have begun to characterize the aberrant regulation of lncRNAs in CC cells and tissues, including Homeobox transcript antisense RNA (HOTAIR), H19, Metastasis-associated lung adenocarcinoma transcript 1 (MALAT1), Cervical Carcinoma High-Expressed 1 (CCHE1), Antisense noncoding RNA in the inhibitors of cyclin-dependent kinase 4 (ANRIL), Growth arrest special 5 (GAS5) and Plasmacytoma variant translocation 1 (PVT1). They have been associated with several disease-related processes such as cell growth, cell proliferation, cell survival, metastasis and invasion as well as therapeutic resistance, and are novel potential biomarkers for diagnosis and prognosis in CC. In this review, we summarize the current literature regarding the knowledge we have about the roles and mechanisms of the lncRNAs in cervical neoplasia.

Long Noncoding RNA LINC01426 Sequesters microRNA-519d-5p to Promote Non-Small Cell Lung Cancer Progression by Increasing ETS1 Expression

PURPOSE

Recent studies have identified important roles for long intergenic non-protein coding RNA 1426 (LINC01426) in glioma and clear cell renal cell carcinoma. The present study evaluated the expression profile of LINC01426 in non-small cell lung cancer (NSCLC) tissues and cell lines. Furthermore, the function of LINC01426 in NSCLC and the molecular mechanisms involved were extensively studied.

METHODS

The abundance of LINC01426 in NSCLC tissues and cell lines was determined using quantitative reverse transcription-polymerase chain reaction. The cell counting kit-8 assay, flow cytometry, transwell experiments for migration and invasion, and xenograft tumor model were used to assess the function of LINC01426 in NSCLC cells. Mechanistic studies were performed using the luciferase reporter assay and RNA immunoprecipitation.

RESULTS

Significant LINC01426 upregulation was observed in NSCLC tissues and cell lines. Silencing LINC01426 inhibited proliferation, migration, and invasion of NSCLC cells and facilitated cell apoptosis in vitro. Furthermore, interference of LINC01426 restricted tumor growth of NSCLC cells in vivo. In addition, LINC01426 showed the ability to directly bind to microRNA-519d-5p (miR-519d-5p) and act as a molecular sponge for miR-519d-5p in NSCLC cells. Furthermore, the ETS proto-oncogene 1 (ETS1) was identified as a direct target of miR-519d-5p and LINC01426 could indirectly upregulate ETS1 expression by sponging miR-519d-5p. Moreover, the cancer-inhibiting activities of LINC01426 knockdown in NSCLC cells were partially offset by miR-519d-5p inhibition.

CONCLUSION

LINC01426 increases ETS1 expression by sequestering miR-519d-5p, thereby aggravating the malignant progression of NSCLC. The LINC01426/miR-519d-5p/ETS1 competing endogenous RNA pathway may provide a target for designing therapeutic agents for NSCLC treatment.

NORAD regulates epithelial‑mesenchymal transition of non‑small cell lung cancer cells via miR‑422a

The poor prognosis of non‑small cell lung cancer (NSCLC) is related to epithelial‑mesenchymal transition (EMT). Recent studies demonstrated that non‑coding RNA activated by DNA damage (NORAD) displays a carcinogenic effect and targets microRNA (miR)‑422a, which may be involved in tumor cell migration and invasion. The aim of the present study was to investigate the effect of NORAD on NSCLC cell EMT and the underlying mechanism. Reverse transcription‑quantitative PCR and western blotting were performed to detect the expression levels of long non‑coding RNAs, miRNAs and mRNAs. Cell viability, migration and invasion were detected by conducting Cell Counting Kit‑8, wound healing and Transwell assays, respectively. The target of NORAD was predicted using starBase and further confirmed by conducting a dual‑luciferase reporter assay. The results indicated that NORAD expression was significantly increased in lung cancer tissues and cells compared with adjacent healthy tissues and cells. Compared with the control groups, NORAD overexpression promoted SK‑MES‑1 cell viability, migration and invasion, whereas NORAD knockdown resulted in the opposite effects in A549 cells. Moreover, miR‑422a, which was predicted to be a target of NORAD, displayed lower expression levels in lung cancer tissues compared with adjacent healthy tissues. In addition, miR‑422a overexpression partially reversed NORAD overexpression‑induced increases in SK‑MES‑1 cell viability, migration, invasion and EMT. In addition, miR‑422a knockdown partially reversed the effects of NORAD knockdown. The present study suggested that NORAD regulated lung cancer cell EMT by regulating the expression of miR‑422a, providing a potential therapeutic target for the intervention of the development of NSCLC.

The prognostic significance of long non-coding RNAs in hepatocellular carcinoma: An updated meta-analysis

BACKGROUND

Recently, many studies have demonstrated that long non-coding RNAs (lncRNAs) are abnormally expressed in hepatocellular carcinoma (HCC) and may serve as a potential molecular biomarker to evaluate the prognosis of hepatocellular carcinoma. Therefore, we accomplished a meta-analysis built on current studies to assess the prognostic value of lncRNAs in hepatocellular carcinoma.

METHODS

The PubMed database was carefully searched to collect all eligible studies until February 20, 2019. The pooled hazard ratios (HRs) and 95% confidence intervals (CIs) of the overall survival, relapse-free survival, and progression-free survival were calculated to evaluate the prognostic significance of lncRNAs expression in hepatocellular carcinoma using Stata12.0 software. Heterogeneity, sensitivity analysis, and publication bias were also evaluated.

RESULTS

The results showed that the expression level of lncRNAs was significantly correlated with clinical outcomes. Abnormally expressed lncRNAs predicted poor overall survival (HR=2.19, 95% CI: 1.99-2.42, P<0.001; I²=44.7%, P=0.005), relapse-free survival (HR=2.68, 95% CI: 1.74-4.14, P<0.001; I²=0.0%, P=0.763) and progression-free survival of hepatocellular carcinoma patients (HR=2.44, 95% CI: 1.53-3.89, P<0.001; I²=0.0%, P=0.336). Statistical significance was also noted in subgroup meta-analyses that were stratified by follow-up time, cutoff value, and quality score. Moreover, the pooled results indicated that lncRNAs expression was significantly associated with tumor size (HR=1.48, 95% CI: 1.24-1.79), tumor number (HR=1.34, 95% CI: 1.08-1.66), and tumor node metastasis stage (HR=2.10, 95% CI: 1.48-2.99), but not liver cirrhosis and tumor differentiation (P>0.05).

CONCLUSIONS

This meta-analysis indicates that lncRNAs are strongly associated with prognosis in hepatocellular carcinoma and may serve as a promising indicator for prognostic evaluation of patients with hepatocellular carcinoma. But larger clinical studies are needed to verify its feasibility.

Mechanisms of Taxane Resistance

The taxane family of chemotherapy drugs has been used to treat a variety of mostly epithelial-derived tumors and remain the first-line treatment for some cancers. Despite the improved survival time and reduction of tumor size observed in some patients, many have no response to the drugs or develop resistance over time. Taxane resistance is multi-faceted and involves multiple pathways in proliferation, apoptosis, metabolism, and the transport of foreign substances. In this review, we dive deeper into hypothesized resistance mechanisms from research during the last decade, with a focus on the cancer types that use taxanes as first-line treatment but frequently develop resistance to them. Furthermore, we will discuss current clinical inhibitors and those yet to be approved that target key pathways or proteins and aim to reverse resistance in combination with taxanes or individually. Lastly, we will highlight taxane response biomarkers, specific genes with monitored expression and correlated with response to taxanes, mentioning those currently being used and those that should be adopted. The future directions of taxanes involve more personalized approaches to treatment by tailoring drug-inhibitor combinations or alternatives depending on levels of resistance biomarkers. We hope that this review will identify gaps in knowledge surrounding taxane resistance that future research or clinical trials can overcome.

Spliceosome-Associated microRNAs Signify Breast Cancer Cells and Portray Potential Novel Nuclear Targets

MicroRNAs (miRNAs) act as negative regulators of gene expression in the cytoplasm. Previous studies have identified the presence of miRNAs in the nucleus. Here we study human breast cancer-derived cell-lines (MCF-7 and MDA-MB-231) and a non-tumorigenic cell-line (MCF-10A) and compare their miRNA sequences at the spliceosome fraction (SF). We report that the levels of miRNAs found in the spliceosome, their identity, and pre-miRNA segmental composition are cell-line specific. One such miRNA is miR-7704 whose genomic position overlaps HAGLR, a cancer-related lncRNA. We detected an inverse expression of miR-7704 and HAGLR in the tested cell lines. Specifically, inhibition of miR-7704 caused an increase in HAGLR expression. Furthermore, elevated levels of miR-7704 slightly altered the cell-cycle in MDA-MB-231. Altogether, we show that SF-miR-7704 acts as a tumor-suppressor gene with HAGLR being its nuclear target. The relative levels of miRNAs found in the spliceosome fractions (e.g., miR-100, miR-30a, and let-7 family) in non-tumorigenic relative to cancer-derived cell-lines was monitored. We found that the expression trend of the abundant miRNAs in SF was different from that reported in the literature and from the observation of large cohorts of breast cancer patients, suggesting that many SF-miRNAs act on targets that are different from the cytoplasmic ones. Altogether, we report on the potential of SF-miRNAs as an unexplored route for cancerous cell state.

HOXD-AS1 facilitates cell migration and invasion as an oncogenic lncRNA by competitively binding to miR-877-3p and upregulating FGF2 in human cervical cancer

Background

Long non-coding RNAs (LncRNAs) are dysregulated in multiple human cancers and they are highly involved in tumor progression. Previous studies have identified the oncogenic lncRNA HOXD cluster antisense RNA 1 (HOXD-AS1) in human cancers, while its roles in cervical cancer (CC) remain unclear. Herein we intended to characterize the implication of HOXD-AS1 in CC.

Methods

qRT-PCR was applied to examine the relative expression of HOXD-AS1 in CC tissues, cell lines and transfected cells. Wound healing and transwell assays were applied to detect cell migration and invasion alteration. The targeting relationship between miRNA and mRNA/lncRNA was determined by dual luciferase reporter, qRT-PCR and western blot assays.

Results

HOXD-AS1 was overexpressed in CC tissues and cell lines. Its higher level predicted worse prognosis of CC patients. SiRNA mediated knockdown of HOXD-AS1 repressed CC cell migration and invasion, and its overexpression did the opposite. Mechanistically, HOXD-AS1 acted as a competing endogenous RNA (ceRNA) to sponge miR-877-3p and led to upregulation of FGF2, a target of miR-877-3p. Importantly, either miR-877-3p overexpression or FGF2 inhibition could abolish the migration and invasion promotion induced by HOXD-AS1.

Conclusion

HOXD-AS1 functions as a tumor-promoting lncRNA via the miR-877-3p/FGF2 axis in CC. HOXD-AS1 might be a promising therapeutic target as well as a novel prognostic biomarker for CC.

m6 A transferase METTL3-induced lncRNA ABHD11-AS1 promotes the Warburg effect of non-small-cell lung cancer

N⁶ -methyladenosine (m⁶ A) and long noncoding RNAs (lncRNAs) are both crucial regulators in non-small-cell lung cancer (NSCLC) tumorigenesis. However, the pathological roles of m⁶ A and lncRNAs in NSCLC progression are still limited and undefined. Here, lncRNA ABHD11-AS1 was upregulated in NSCLC tissue specimens and cells and the ectopic overexpression was closely correlated with unfavorable prognosis of NSCLC patients. Functionally, ABHD11-AS1 promoted the proliferation and Warburg effect of NSCLC. Mechanistically, m⁶ A profile was analyzed by methylated RNA immunoprecipitation sequencing (MeRIP-Seq). MeRIP-Seq presented that there was m⁶ A modification site in ABHD11-AS1. m⁶ A methyltransferase-like 3 (METTL3) installed the m⁶ A modification and enhanced ABHD11-AS1 transcript stability to increase its expression. In conclusion, our findings highlight the function and mechanism of METTL3-induced ABHD11-AS1 in NSCLC and inspire the understanding of m⁶ A and lncRNA in cancer biology.

cfRNAs as biomarkers in oncology - still experimental or applied tool for personalized medicine already?

Currently, the challenges of contemporary oncology are focused mainly on the development of personalized medicine and precise treatment, which could be achieved through the use of molecular biomarkers. One of the biological molecules with great potential are circulating free RNAs (cfRNAs) which are present in various types of body fluids, such as blood, serum, plasma, and saliva. Also, different types of cfRNA particles can be distinguished depending on their length and function: microRNA (miRNA), PIWI-interacting RNA (piRNA), tRNA-derived RNA fragments (tRFs), circular RNA (circRNA), long non-coding RNA (lncRNA), and messenger RNA (mRNA). Moreover, cfRNAs occur in various forms: as a free molecule alone, in membrane vesicles, such as exosomes, or in complexes with proteins and lipids. One of the modern approaches for monitoring patient's condition is a "liquid biopsy" that provides a non-invasive and easily available source of circulating RNAs. Both the presence of specific cfRNA types as well as their concentration are dependent on many factors including cancer type or even reaction to treatment. Despite the possibility of using circulating free RNAs as biomarkers, there is still a lack of validated diagnostic panels, defined protocols for sampling, storing as well as detection methods. In this work we examine different types of cfRNAs, evaluate them as possible biomarkers, and analyze methods of their detection. We believe that further research on cfRNA and defining diagnostic panels could lead to better and faster cancer identification and improve treatment monitoring.

lncRNA and Mechanisms of Drug Resistance in Cancers of the Genitourinary System

Available systemic treatment options for cancers of the genitourinary system have experienced great progress in the last decade. However, a large proportion of patients eventually develop resistance to treatment, resulting in disease progression and shorter overall survival. Biomarkers indicating the increasing resistance to cancer therapies are yet to enter clinical routine. Long non-coding RNAs (lncRNA) are non-protein coding RNA transcripts longer than 200 nucleotides that exert multiple types of regulatory functions of all known cellular processes. Increasing evidence supports the role of lncRNAs in cancer development and progression. Additionally, their involvement in the development of drug resistance across various cancer entities, including genitourinary malignancies, are starting to be discovered. Consequently, lncRNAs have been suggested as factors in novel therapeutic strategies to overcome drug resistance in cancer. In this review, the existing evidences on lncRNAs and their involvement in mechanisms of drug resistance in cancers of the genitourinary system, including renal cell carcinoma, bladder cancer, prostate cancer, and testicular cancer, will be highlighted and discussed to facilitate and encourage further research in this field. We summarize a significant number of lncRNAs with proposed pathways in drug resistance and available reported studies.

Development and validation of a five-lncRNA signature with prognostic value in colon cancer

Dysregulation of long noncoding RNAs (lncRNAs) has been found in a large number of human cancers, including colon cancer. Therefore, the implementation of potential lncRNAs biomarkers with prognostic prediction value are very much essential. GSE39582 data set was downloaded from database of Gene Expression Omnibus. Re-annotation analysis of lncRNA expression profiles was performed by NetAffx annotation files. Univariate and multivariate Cox proportional analyses helped select prognostic lncRNAs. Algorithm of random survival forest-variable hunting (RSF-VH) together with stepwise multivariate Cox proportional analysis were performed to establish lncRNA signature. The log-rank test was carried out to analyze and compare the Kaplan-Meier survival curves of patients' overall survival (OS). Receiver operating characteristic (ROC) analysis was used for comparing the survival prediction regarding its specificity and sensitivity based on lncRNA risk score, followed by calculating the values of area under the curve (AUC). The single-sample GSEA (ssGSEA) analysis was used to describe biological functions associated with this signature. Finally, to determine the robustness of this model, we used the validation sets including GSE17536 and The Cancer Genome Atlas data set. After re-annotation analysis of lncRNAs, a total of 14 lncRNA probes were obtained by univariate and multivariate Cox proportional analysis. Then, the RSF-VH algorithm and stepwise multivariate Cox analysis helped to build a five-lncRNA prognostic signature for colon cancer. The patients in group with high risk showed an obviously shorter survival time compared with patients in group with low risk with AUC of 0.75. In addition, the five-lncRNA signature can be used to independently predict the survival of patients with colon cancer. The ssGSEA analysis revealed that pathways such as extracellular matrix-receptor interaction was activated with an increase in risk score. These findings determined the strong power of prognostic prediction value of this five-lncRNA signature for colon cancer.

Antisense lncRNA LDLRAD4-AS1 promotes metastasis by decreasing the expression of LDLRAD4 and predicts a poor prognosis in colorectal cancer

Long noncoding RNAs (lncRNAs) have been revealed to play critical roles in tumor initiation and progression. The antisense lncRNA LDLRAD4-AS1 is the longest lncRNA of LDLRAD4, and its expression levels, cellular localization, precise function, and mechanism in colorectal cancer (CRC) remain unknown. In this study, we observed that lncRNA LDLRAD4-AS1 was located in the nucleus of CRC cells and that lncRNA LDLRAD4-AS1 was upregulated in most CRC specimens and cell lines. Overexpression of lncRNA LDLRAD4-AS1 was correlated with poor prognosis in CRC patients. LncRNA LDLRAD4-AS1 upregulation enhanced the migration and invasion of CRC cells in vitro and facilitated CRC metastasis in vivo. Mechanistic investigations suggested that lncRNA LDLRAD4-AS1 could decrease the expression of LDLRAD4 by disrupting the stability of LDLRAD4 mRNA, resulting in epithelial-to-mesenchymal transition (EMT) through upregulating Snail, thereby promoting metastasis in CRC. Our results demonstrated a previously unrecognized LDLRAD4-AS1-LDLRAD4-Snail regulatory axis involved in epigenetic and posttranscriptional regulation that contributes to CRC progression and metastasis.

Propofol facilitates cisplatin sensitivity via lncRNA MALAT1/miR-30e/ATG5 axis through suppressing autophagy in gastric cancer

AIMS

Recently, chemoresistance has been recognized as an obstacle in the treatment of gastric cancer (GC). The aim of this study was to investigate the biological functions and underlying mechanisms of propofol in GC chemoresistance.

MAIN METHODS

CCK-8 assay, flow cytometry and immunofluorescent staining were performed to assess the IC₅₀ concentration, cell apoptosis and autophagy activity of cisplatin in both GC chemosensitive cells (SGC7901) and chemoresistant cells (SGC7901/CDDP). The expression pattern of MALAT1 in GC cells was detected by qRT-PCR. The shRNAs and overexpressing plasmids were employed for the loss or gain-of-function. Dual-luciferase reporter assay was subjected to verify the binding relationship between MALAT1 and miR-30e. Besides, ATG5 mRNA and protein levels were determined using qRT-PCR and western blot analysis. Furthermore, GC xenograft mice model was established to validate the in vitro findings.

KEY FINDINGS

Chemoresistant GC cells presented higher IC₅₀ of cisplatin, increased autophagy activity and stronger expression of MALAT1. The application of propofol promoted cell apoptosis and reduced the activity of autophagy through downregulating MALAT1. Silencing of MALAT1 inhibited chemo-induced autophagy, whereas MALAT1 overexpression promoted autophagy in GC cells. Mechanistic researches demonstrated that MALAT1 could bind with miR-30e to regulate ATG5 expression, thus causing the suppression of autophagy. In vivo GC xenograft model treated with both propofol and cisplatin also showed significantly decreased tumor size and weight, which was enhanced by knockdown of MALAT1.

SIGNIFICANCE

Altogether, our study revealed a novel mechanism of propofol of lncRNA MALAT1/miR-30e/ATG5 mediated autophagy-related chemoresistance in GC, casting new lights on the understanding of propofol.

Bioinformatics analysis of LINC00426 expression in lung cancer and its correlation with patients' prognosis

Background

To investigate the expression of long noncoding RNA (lncRNA) LINC00426 (long intergenic nonprotein coding RNA 426) in non‐small cell lung cancer (NSCLC) patients and its correlation with their prognosis.

Methods

The expression of long noncoding RNA LINC00426 of non‐small cell lung cancer (NSCLC) in The Cancer Genome Atlas (TCGA) database was screened. According to the expression level of LINC00426 in tumor tissue of NSCLC patients, the patients were divided into high and low LINC00426 expression groups. The correlation between LINC00426 expression group and the prognosis of the patient was analyzed by log‐rank test. A total of 72 NSCLC patients who had undergone surgery were retrospectively included in this study. LINC00426 relative expression of tumor and normal lung tissue of the included 72 NSCLC patients were examined by real‐time quantitative PCR assay. The correlation between LINC00426 expression and the patients’ clinical characteristics were also evaluated.

Results

LINC00426 relative expression was not statistically different between cancer and normal tissue (P > 0.05) of NSCLC patients in the TCGA database. The amplification and deep deletion mutation of LINC00426 gene was found in 0.5% of NSCLC patients. The overall survival (OS) of the LINC00426 high expression group was significantly higher than that of the low expression group (HR = 0.81, P = 0.044), while there was no significant difference between the high and low expression group (HR = 0.97, P = 0.82) for disease‐free survival (DFS). LINC0042646 expression level was elevated in 46 cases in normal lung tissue compared to the tumor tissue of the 72 NSCLC patients. LINC0042646 expression level was significantly correlated with the clinical stage (P < 0.05).

Conclusion

Long noncoding RNA LINC00426 was downregulated in the tumor tissue of NSCLC patients and correlated with poor prognosis.

MALAT1 gene expression in colorectal cancer and its clinical significance: Data mining based on multiple gene expression databases

BACKGROUND

Colorectal cancer (CRC) is the most common malignant tumor of the digestive system. Long-chain non-coding RNAs (lncRNAs) play an important role in the occurrence, development, invasion and metastasis of CRC. MALAT1 is a newly discovered lncRNA, and its role in CRC and its relationship with prognosis are not completely clear.

AIM

To explore the differential expression of the lncRNA MALAT1 in CRC and its clinical significance by using bioinformatics data mining technology.

METHODS

BioGPS database was used to analyze the expression of MALAT1 in normal intestinal epithelium. Oncomine was used to meta-analyze the differential expression of MALAT1 in CRC tissue and normal intestinal epithelium tissue, and to analyze the difference of survival time between patients with high and low expression of MALAT1. Protein interaction network analysis was performed based on the STING database to analyze the proteins that potential interact with MALAT1.

RESULTS

The relative expression of MALAT1 in normal colorectal tissues was low. In Oncomine database, there were eight studies on differential expression of CRC, six of which suggested high expression of MALAT1 in CRC and two suggested low expression. The microarray data of 18 CRC and matched normal tissues were compared. The expression of MALAT1 in CRC tissues was significantly higher than that in normal tissues (P = 0.027). There was no significant difference in MALAT1 expression between colon cancer and normal tissues (P = 0.149), but the expression of MALAT1 in rectal cancer was significantly higher than that in normal tissues (P = 1.04 E-5). Kaplan-Meier Plotter analysis demonstrated that the overall survival time of the high and low MALAT1 expression groups was 41.93 months and 52.2 months, respectively, with no significant difference (HR = 0.64, 95%CI: 0.29-1.39, P = 0.25). The possible interaction proteins of MALAT1 were analyzed based on the String database. The results showed that MALAT1 interacts with TP53, SUZ12, CDK4, KDMA, etc. Co-expression analysis showed that MALAT1 protein was co-expressed with EZH2, TP53, SRSF1, and other genes, suggesting that these genes may have similar functions.

CONCLUSION

The expression level of MALAT1 gene in CRC tissues is significantly up-regulated, but there is no correlation between MALAT1 expression and the prognosis of patients. MALAT1 interacts with TP53, SUZ12, CDK4, and KDMA proteins. These interacting proteins include Polycomb-group proteins, cyclin-dependent protein kinase and so on, which are related to gene expression control, transcriptional regulation, and cell division.

Silencing of long noncoding RNA HOXD-AS1 inhibits proliferation, cell cycle progression, migration and invasion of hepatocellular carcinoma cells through MEK/ERK pathway

Accumulating findings reveal that long noncoding RNAs (lncRNAs) as crucial regulatory molecules serve vital functions in the progression of hepatocellular carcinoma (HCC). This study aims to investigate the biological roles and mechanisms of lncRNA HOXD cluster antisense RNA 1 (HOXD-AS1) in HCC cells based on transcriptome analysis. The Cancer Genome Atlas data analysis and experimental validation showed that HOXD-AS1 was increased in HCC tissues/cell lines and positively relevant to histologic grade. The subcellular localization results indicated HOXD-AS1 was dispersed both in the nucleus as well as the cytoplasm of HCC cells. In vitro loss-of-function experiments revealed that silencing of HOXD-AS1 could dramatically suppress the proliferation, migration, and invasion, and induce S or/and G2/M phase cell cycle arrest as well as apoptosis of Bel-7402 and MHCC97H cells accompanying the changes in expression levels of cyclin B1, cyclin D1, BCL-2, BAX, and MMP2. In vivo assay also showed that HOXD-AS1 silencing could markedly reduce xenograft tumor volume and weight of HCC cells. Transcriptome and bioinformatic analysis indicated that a total of 1103 genes were significantly altered by HOXD-AS1 silencing, of which 132 genes exhibited a significant correlation with HOXD-AS1 expression in HCC tissues. Gene Ontology (GO) enrichment analysis revealed differentially expressed genes were remarkably enriched in several cancer-related biological processes (cell proliferation, cell cycle, apoptosis, migration, angiogenesis, and hypoxic response). Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis indicated that HOXD-AS1 has the potential to affect p53, tumor necrosis factor (TNF), mitogen-activated protein kinase (MAPK) pathway, and Western blot results further validated that HOXD-AS1 silencing could inhibit the MEK/ERK pathway in Bel-7402 cells. Collectively, HOXD-AS1, as an oncogenic lncRNA, might exert crucial functions in HCC progression and serve as a potential diagnostic biomarker and therapeutic target for HCC.

Long non-coding RNA-HAGLR suppressed tumor growth of lung adenocarcinoma through epigenetically silencing E2F1

Emerging evidence indicates that long noncoding RNAs (LncRNAs) are new players in gene regulation but their mechanisms of action are mainly undocumented. In this study, we investigated LncRNA alterations that contribute to lung cancer by analyzing published microarray data in Gene Expression Obminus (GEO) and The Cancer Genome Atlas RNA (TCGA) sequencing data. Here, we reported that HAGLR (also called HOXD-AS1) was frequently down-regulated in lung adenocarcinoma (LUAD) tissues, and decreased HAGLR expression was clinically associated with shorter survival of LUAD patients. Preclinical studies using multiple LUAD cells and in vivo mouse model indicated that HAGLR could attenuate LUAD cell growth in vitro and in vivo. Mechanistically, HAGLR could physically interact with DNMT1, and recruit DNMT1 on E2F1 promoter to increase local DNA methylation. Overall, our study demonstrated that HAGLR promoted LUAD progression by recruiting DNMT1 to modulate the promoter methylation and expression of E2F1, which expanded potential therapeutic strategies for LUAD treatment.

HOX cluster-embedded antisense long non-coding RNAs in lung cancer

Homeobox (HOX) genes play vital roles in embryonic development and oncogenesis. In humans, there are 39 HOX genes found in four clusters that are located on different chromosomes. The HOX clusters also contain numerous non-protein-coding RNAs, including some lncRNAs. The HOX cluster-embedded lncRNAs (HOX-lncRNAs), most notably, HOTTIP and HOTAIR play a major role in the regulation of their adjacent coding genes. Recently, most HOX-lncRNAs have been shown to impact tumorigenesis and cancer progression. Several HOX-lncRNAs, including HOTTIP, HOXA11-AS, HOTAIRM1, HOXA-AS3, HOXA10-AS, HOTAIR, and HAGLR, are dysregulated in lung cancer. Moreover, their expression levels are correlated with the clinical features of this disease. These HOX-lncRNAs regulate the proliferation, invasion, migration, and chemo-resistance of lung cancer cells through various molecular mechanisms. Although lncRNAs have received much attention lately, the functions of some HOX-lncRNAs in the development of cancer are unclear. Thus, HOX-embedded lncRNAs should be widely investigated in cancer. Here, we review the functions of HOX-lncRNAs in lung cancer.

Emerging Epigenetic Regulation of Circular RNAs in Human Cancer

Circular RNAs (circRNAs) are novel members of the noncoding RNA family. Their characteristic covalent closed-loop structure endows circRNAs that are much more stable than the corresponding linear transcript. circRNAs are ubiquitous in eukaryotic cells, and their functions are diverse and include adsorbing microRNAs (miRNAs; acting as miRNA sponges), regulating transcription, interacting with RNA-binding proteins, and translating and deriving pseudogenes. Moreover, circRNAs are associated with the occurrence and progression of a variety of cancers, acting as new biomarkers for early diagnosis to evaluate curative effects and patient prognosis. Here, this paper briefly describes the characteristics and functions of circRNAs, and it further concludes the relationship between circRNAs and human cancer.

The Role of HOX Transcription Factors in Cancer Predisposition and Progression

Homeobox (HOX) transcription factors, encoded by a subset of homeodomain superfamily genes, play pivotal roles in many aspects of cellular physiology, embryonic development, and tissue homeostasis. Findings over the past decade have revealed that mutations in HOX genes can lead to increased cancer predisposition, and HOX genes might mediate the effect of many other cancer susceptibility factors by recognizing or executing altered genetic information. Remarkably, several lines of evidence highlight the interplays between HOX transcription factors and cancer risk loci discovered by genome-wide association studies, thereby gaining molecular and biological insight into cancer etiology. In addition, deregulated HOX gene expression impacts various aspects of cancer progression, including tumor angiogenesis, cell autophagy, proliferation, apoptosis, tumor cell migration, and metabolism. In this review, we will discuss the fundamental roles of HOX genes in cancer susceptibility and progression, highlighting multiple molecular mechanisms of HOX involved gene misregulation, as well as their potential implications in clinical practice.