lncRNA XIST regulates proliferation and migration of hepatocellular carcinoma cells by acting as miR-497-5p molecular sponge and targeting PDCD4

Role of Non-coding RNAs on the Radiotherapy Sensitivity and Resistance in Cancer Cells

Radiotherapy (RT) is an integral part of treatment management in cancer patients. However, one of the limitations of this treatment method is the resistance of cancer cells to radiotherapy. These restrictions necessitate the introduction of modalities for the radiosensitization of cancer cells. It has been shown that Noncoding RNAs (ncRNAs), along with modifiers, can act as radiosensitivity and radioresistant regulators in a variety of cancers by affecting double strand break (DSB), wnt signaling, glycolysis, irradiation induced apoptosis, ferroptosis and cell autophagy. This review will provide an overview of the latest research on the roles and regulatory mechanisms of ncRNA after RT in in vitro and preclinical researches.

Dynamic role of exosomal long non-coding RNA in liver diseases: pathogenesis and diagnostic aspects

BACKGROUND

Liver disease has emerged as a significant health concern, characterized by high rates of morbidity and mortality. Circulating exosomes have garnered attention as important mediators of intercellular communication, harboring protein and stable mRNAs, microRNAs, and long non-coding RNAs (lncRNA). This review highlights the involvement of exosomal lncRNA in the pathogenesis and diagnosis of various liver diseases. Notably, exosomal lncRNAs exhibit therapeutic potential as targets for conditions including hepatic carcinoma, hepatic fibrosis, and hepatic viral infections.

METHOD

An online screening process was employed to identify studies investigating the association between exosomal lncRNA and various liver diseases.

RESULT

Our study revealed a diverse array of lncRNAs carried by exosomes, including H19, Linc-ROR, VLDLR, MALAT1, DANCR, HEIH, ENSG00000248932.1, ENST00000457302.2, ZSCAN16-AS1, and others, exhibiting varied levels across different liver diseases compared to normal liver tissue. These exosomal-derived lncRNAs are increasingly recognized as pivotal biomarkers for diagnosing and prognosticating liver diseases, supported by emerging evidence. However, the precise mechanisms underlying the involvement of certain exosomal lncRNAs remain incompletely understood. Furthermore, the combined analysis of serum exosomes using ENSG00000258332.1, LINC00635, and serum AFP may serve as novel and valuable biomarker for HCC. Clinically, exosomal ATB expression is upregulated in HCC, while exosomal HEIH and RP11-513I15.6 have shown potential for distinguishing HCC related to HCV infection.

CONCLUSION

The lack of reliable biomarkers for liver diseases, coupled with the high specificity and sensitivity of exosomal lncRNA and its non-invasive detection, promotes exploring their role in pathogenesis and biomarker for diagnosis, prognosis, and response to treatment liver diseases.

Current understanding of functional peptides encoded by lncRNA in cancer

Dysregulated gene expression and imbalance of transcriptional regulation are typical features of cancer. RNA always plays a key role in these processes. Human transcripts contain many RNAs without long open reading frames (ORF, > 100 aa) and that are more than 200 bp in length. They are usually regarded as long non-coding RNA (lncRNA) which play an important role in cancer regulation, including chromatin remodeling, transcriptional regulation, translational regulation and as miRNA sponges. With the advancement of ribosome profiling and sequencing technologies, increasing research evidence revealed that some ORFs in lncRNA can also encode peptides and participate in the regulation of multiple organ tumors, which undoubtedly opens a new chapter in the field of lncRNA and oncology research. In this review, we discuss the biological function of lncRNA in tumors, the current methods to evaluate their coding potential and the role of functional small peptides encoded by lncRNA in cancers. Investigating the small peptides encoded by lncRNA and understanding the regulatory mechanisms of these functional peptides may contribute to a deeper understanding of cancer and the development of new targeted anticancer therapies.

Long noncoding RNA XIST: a novel independent prognostic biomarker for patients with ABC-DLBCL receiving R-CHOP treatment

Approximately one-third of activated B-cell-like diffuse large B-cell lymphoma (ABC-DLBCL) cases were unresponsive to standard first-line therapy; thus, identifying biomarkers to evaluate therapeutic efficacy and assessing the emergence of drug resistance is crucial. Through early-stage screening, long noncoding RNA (lncRNA) X-inactive specific transcript (XIST) was found to be correlated with the R-CHOP treatment response. This study aimed to clarify the characteristics of XIST in ABC-DLBCL. The expression level of XIST in 161 patients with ABC-DLBCL receiving R-CHOP therapy was examined via RNA in situ hybridization, and the association between XIST expression and clinicopathological features, treatment response and prognosis was analyzed in the study cohort and validated in the Gene Expression Omnibus cohort. Cell biological experiments and bioinformatics analyses were conducted to reveal aberrant signaling. The proportion of complete response in patients with high XIST expression was lower than that in patients with low XIST expression (53.8% versus 77.1%) (P = 0.002). High XIST expression was remarkably associated with the characteristics of tumor progression and was an independent prognostic element for overall survival (P = 0.039) and progression-free survival (P = 0.027) in ABC-DLBCL. XIST was proven to be involved in m6A-related methylation and ATF6-associated autophagy. XIST knockdown repressed ABC-DLBCL cellular proliferation by regulating Raf/MEK/ERK signaling. High XIST expression was associated with ABC-DLBCL tumorigenesis and development and contributed to R-CHOP treatment resistance. XIST may be a promising signal to predict ABC-DLBCL prognosis.

METTL14-mediated lncRNA XIST silencing alleviates GDM progression by facilitating trophoblast cell proliferation and migration via the miR-497-5p/FOXO1 axis

Gestational diabetes mellitus (GDM), a prevalent complication during the gestation period, has been linked to impaired proliferation and migration of trophoblasts causing placental maldevelopment. We previously found that lncRNA X-inactive specific transcript (XIST) played an essential role in GDM progression. Here, we investigated the precise biological functions as well as the upstream and downstream regulatory mechanisms of XIST in GDM. We found that XIST and forkhead box O1 (FOXO1) were conspicuously upregulated and miR-497-5p and methyltransferase-like 14 (METTL14) were downregulated in the placentas of GDM patients. XIST silencing facilitated proliferation and migration and inhibited cell apoptosis and cell cycle arrest in HG-cultured HTR8/SVneo cells. METTL14 inhibited XIST expression through m6A methylation modification. XIST overexpression abrogated the positive effect of METTL14 overexpression on HG-cultured HTR8/SVneo cell progression. MiR-497-5p and FOXO1 are downstream regulatory genes of XIST in HTR8/SVneo cells. Reverse experiments illustrated that XIST mediated HTR8/SVneo cell functions by regulating the miR-497-5p/FOXO1 axis. Additionally, XIST silencing augmented glucose tolerance and alleviated fetal detrimental changes in GDM rats. To conclude, METTL14-mediated XIST silencing facilitated proliferation and migration and inhibited cell apoptosis and cell cycle arrest in HG-cultured HTR8/SVneo cells via the miR-497-5p/FOXO1 axis, thereby alleviating GDM progression in rats.

Mesenchymal Stem Cell-Derived from Dental Tissues-Related lncRNAs: A New Regulator in Osteogenic Differentiation

Odontogenic stem cells are mesenchymal stem cells (MSCs) with multipotential differentiation potential from different dental tissues. Their osteogenic differentiation is of great significance in bone tissue engineering. In recent years, it has been found that long noncoding RNAs (lncRNAs) participate in regulating the osteoblastic differentiation of stem cells at the epigenetic level, transcriptional level, and posttranscriptional level. We reviewed the existing lncRNA related to the osteogenic differentiation of odontogenic stem cells and emphasized the critical mechanism of lncRNA in the osteogenic differentiation of odontogenic stem cells. These findings are expected to be an important target for promoting osteoblastic differentiation of odontogenic stem cells in bone regeneration therapy with lncRNA.

Circulating LncRNAs landscape as potential biomarkers in breast cancer

BACKGROUND

In Iran, the delay in diagnosis and treatment of breast cancer results in low survival rates.

AIM

It is essential to characterize new therapeutic targets and prognostic breast cancer biomarkers. The rising evidence suggested that long non-coding RNAs (lncRNAs) expression levels are deregulated in human cancers and can use as biomarkers for the rapid diagnosis of breast cancer.

METHODS

In the present study, a quantitative real-time polymerase chain reaction (qRT-PCR) technique was used to measure 20 oncogenic and tumor suppressor lncRNAs expression levels in whole blood samples of female breast cancer patients and healthy women. Receiver operating characteristic curve (ROC) was used to assess the diagnostic value of each selected lncRNA as a biomarker.

RESULTS

The results revealed that some circulating lncRNAs (MEG3, NBAT1, NKILA, GAS5, EPB41L4A-AS2, Z38, and BC040587) were significantly down-regulated in breast cancer patients compared to healthy women. In contrast, other circulating lncRNAs (H19, SPRY4-IT1, XIST, UCA1, AC026904.1, CCAT1, CCAT2, ITGB2-AS, and AK058003) were significantly up-regulated in breast cancer patients compared to controls. It was shown that the expression levels of NKILA, and NBAT1 lncRNAs were related to tumor size, and BC040587 expression level related to age, node metastasis, tumor size, and grade (p < .05). The association between H19 and SPRY4-IT1 lncRNAs with HER-2 was confirmed statistically (p < .05). ROC curves illustrated that the blood levels of SPRY4-IT1, XIST, and H19 lncRNAs have excellent potential in discriminating breast cancer from the healthy controls, showing an AUC of 1.0 (95% CI 1.0-1.0, p = .00), 0.898 (95% CI 0.815-0.981, p = .00), and 0.848 (95% CI 0.701-0.995, p = .01), respectively.

CONCLUSION

In conclusion, the expression levels of circulating H19 and SPRY4-IT1 lncRNAs in breast cancer patients could consider as the prognostic biomarkers and therapeutic targets in breast cancer, because of their excellent power in discriminating breast cancer from healthy individuals and the significant correlation of H19, and SPRY4-IT1 lncRNAs with clinicopathological traits. We also suggest the possible application of BC040587 lncRNA as a diagnostic and prognostic indicator to assess tumor progression in case of verification in larger patients' cohorts.

Long non-coding RNAs (lncRNAs) in hepatocellular carcinoma progression: Biological functions and new therapeutic targets

Liver is an important organ in body that performs vital functions such as detoxification. Liver is susceptible to development of cancers, and hepatocellular carcinoma (HCC) is among them. 75-85% of liver cancer cases are related to HCC. Therefore, much attention has been directed towards understanding factors mediating HCC progression. LncRNAs are epigenetic factors with more than 200 nucleotides in length located in both nucleus and cytoplasm and they are promising candidates in cancer therapy. Directing studies towards understanding function of lncRNAs in HCC is of importance. LncRNAs regulate cell cycle progression and growth of HCC cells, and they can also induce/inhibit apoptosis in tumor cells. LncRNAs affect invasion and metastasis in HCC mainly by epithelial-mesenchymal transition (EMT) mechanism. Revealing the association between lncRNAs and downstream signaling pathways in HCC is discussed in the current manuscript. Infectious diseases can affect lncRNA expression in mediating HCC development and then, altered expression level of lncRNA is associated with drug resistance and radio-resistance. Biomarker application of lncRNAs and their role in prognosis and diagnosis of HCC are also discussed to pave the way for treatment of HCC patients.

Extracellular vesicle expansion of PMIS-miR-210 expression inhibits colorectal tumour growth via apoptosis and an XIST/NME1 regulatory mechanism

BACKGROUND

Colorectal cancer (CRC) has a high mortality rate, and therapeutic approaches to treat these cancers are varied and depend on the metabolic state of the tumour. Profiles of CRC tumours have identified several biomarkers, including microRNAs. microRNA-210 (miR-210) levels are directly correlated with CRC survival. miR-210 expression is higher in metastatic colon cancer cells versus non-metastatic and normal colon epithelium. Therefore, efficient methods to inhibit miR-210 expression in CRC may provide new advances in treatments.

METHODS

Expression of miRs was determined in several metastatic and non-metastatic cell lines. miR-210 expression was inhibited using PMIS-miR-210 in transduced cells, which were transplanted into xenograft mice. In separate experiments, CRC tumours were allowed to grow in xenograft mice and treated with therapeutic injections of PMIS-miR-210. Molecular and biochemical experiments identified several new pathways targeted by miR-210 inhibition.

RESULTS

miR-210 inhibition can significantly reduce tumour growth of implanted colon cancer cells in xenograft mouse models. The direct administration of PMIS-miR-210 to existing tumours can inhibit tumour growth in both NSG and Foxn1nu/j mouse models and is more efficacious than capecitabine treatments. Tumour cells further transfer the PMIS-miR-210 inhibitor to neighbouring cells by extracellular vesicles to inhibit miR-210 throughout the tumour. miR-210 inhibition activates the cleaved caspase 3 apoptotic pathway to reduce tumour formation. We demonstrate that the long non-coding transcript XIST is regulated by miR-210 correlating with decreased XIST expression in CRC tumours. XIST acts as a competing endogenous RNA for miR-210, which reduces XIST levels and miR-210 inhibition increases XIST transcripts in the nucleus and cytoplasm. The increased expression of NME1 is associated with H3K4me3 and H3K27ac modifications in the NME1 proximal promoter by XIST.

CONCLUSION

Direct application of the PMIS-miR-210 inhibitor to growing tumours may be an effective colorectal cancer therapeutic.

CircSOD2 Contributes to Tumor Progression, Immune Evasion and Anti-PD-1 Resistance in Hepatocellular Carcinoma by Targeting miR-497-5p/ANXA11 Axis

Circular RNAs (circRNAs) can function as functional molecules in hepatocellular carcinoma (HCC). Herein, circRNA superoxide dismutase 2 (circSOD2) was researched in HCC progression and immune system. The real-time polymerase chain reaction (qRT-PCR) was used for quantification of circSOD2, microRNA-497-5p (miR-497-5p) and Annexin A11 (ANXA11). Cell assays were performed by 3-(4, 5-dimethylthiazol-2-y1)-2, 5-diphenyl tetrazolium bromide (MTT) and colony formation assays for proliferation, flow cytometry for apoptosis and cell cycle, wound healing assay for migration and transwell assay for migration/invasion. ANXA11 and metastatic protein levels were measured by western blot. Dual-luciferase reporter and RNA immunoprecipitation (RIP) assays were performed to analyze target binding. CD8⁺ T cell immunity was assessed by Immunohistochemistry (IHC) assay, and the effect of circSOD2 on programmed cell death 1 (PD-1) immune checkpoint inhibitors (anti-PD-1) therapy was evaluated by mice xenograft assay. CircSOD2 was upregulated in HCC tissues and cells. Knockdown of circSOD2 resulted in HCC cell growth inhibition, apoptosis promotion, cell cycle arrest and metastasis suppression. Mechanically, circSOD2 promoted HCC development by acting as a miR-497-5p sponge and miR-497-5p played a tumor-inhibitory role in HCC cells by targeting ANXA11. Moreover, circSOD2 induced upregulation of ANXA11 expression by interacting with miR-497-5p. Also, the promoting effects of circSOD2 on immune evasion and anti-PD-1 resistance were related to miR-497-5p/ANXA11 axis. This study elucidated the pivotal function of circSOD2 in HCC progression and immunosuppression by mediating miR-497-6p/ANXA11 axis. CircSOD2/miR-497-5p/ANXA11 axis was a novel view of circRNA research in HCC.

Long non-coding RNA X-inactive specific transcript suppresses the progression of hepatocellular carcinoma through microRNA-221-3p-targeted regulation of O6-methylguanine-DNA methyltransferase

MicroRNA-221-3p (miR-221-3p) is an important regulator involved in the progression and prognosis of various cancers. In this study, we aimed to investigate the diagnostic and prognostic value of miR-221-3p expression along with long non-coding RNA X–inactive specific transcript (XIST), which was identified as its upstream regulator in hepatocellular carcinoma (HCC) by bioinformatics analysis, and further validated by RNA immunoprecipitation (RIP) and dual-luciferase reporter assays. Their expression was measured in tumor tissues and corresponding non-tumor tissues by quantitative real-time PCR (qRT-PCR), which revealed that XIST was weakly expressed in HCC cells and tumors, while miR-221-3p was overexpressed. Complete knockdown of XIST enhanced HCC cell proliferation and migration and inhibited apoptosis, as observed by MTT, transwell, and flow cytometry experiments, respectively. Animal studies validated that XIST knockdown induces tumor growth in vivo. In contrast, upregulation of XIST in HCC cells suppressed their proliferation and migration, stimulated apoptosis, and retarded the growth rate of tumors in vivo. These effects were partially reversed by upregulating miR-221-3p expression. Furthermore, we demonstrated that O⁶-methylguanine-DNA methyltransferase (MGMT) is a downstream target of miR-221-3p. It was weakly expressed in HCC cells and tumors and showed a negative correlation with miR-221-3p. Forced MGMT expression repressed proliferation and migration and enhanced apoptosis in HCC cells. Nevertheless, these anti-tumor effects induced by MGMT overexpression could be abolished by miR-221-3p upregulation. Collectively, our findings reveal that XIST blocks the development of HCC through miR-221-3p-targeted regulation of MGMT. This reveals a new mechanism involved in the development of HCC.

Expression and Clinical Values of Serum miR-155 and miR-224 in Chinese Patients with HCV Infection

Background

To investigate the expression of serum miR-155 and miR-224 among patients with hepatitis C virus (HCV) infection and analyze their clinical values.

Methods

A total of 116 patients suffering from HCV infection admitted to our hospital and 70 healthy subjects were selected. According to the diagnostic results, patients with HCV infection were divided into 48 cases of chronic hepatitis C (CHC), 43 cases of liver cirrhosis and 25 cases of hepatocellular carcinoma (HCC). The expression signature for miR-155 and miR-224 was detected in serum samples. ROC curve and Pearson correlation test were conducted to investigate their diagnostic value and correlation.

Results

The expression extent for serum miR-155 and miR-224 increased along with the increase of malignancy (all P < 0.05). According to ROC curve, the area under the curve (0.918, 95% CI: 0.856–0.974) of miR-155 and miR-224 combined in the diagnosis of HCC was the largest, and its sensitivity and specificity were 93.0% and 86.2%. There is a positive relationship for expression level between miR-155 and miR-224 in CHC and HCC group (all P < 0.001).

Conclusion

miR-155 and miR-224 are remarkably increased in patients suffering from HCV infection. The combination of miR-155 and miR-224 has a good diagnostic value for HCC caused by HCV infection.

The lncRNAs at X Chromosome Inactivation Center: Not Just a Matter of Sex Dosage Compensation

Non-coding RNAs (ncRNAs) constitute the majority of the transcriptome, as the result of pervasive transcription of the mammalian genome. Different RNA species, such as lncRNAs, miRNAs, circRNA, mRNAs, engage in regulatory networks based on their reciprocal interactions, often in a competitive manner, in a way denominated “competing endogenous RNA (ceRNA) networks” (“ceRNET”): miRNAs and other ncRNAs modulate each other, since miRNAs can regulate the expression of lncRNAs, which in turn regulate miRNAs, titrating their availability and thus competing with the binding to other RNA targets. The unbalancing of any network component can derail the entire regulatory circuit acting as a driving force for human diseases, thus assigning “new” functions to “old” molecules. This is the case of XIST, the lncRNA characterized in the early 1990s and well known as the essential molecule for X chromosome inactivation in mammalian females, thus preventing an imbalance of X-linked gene expression between females and males. Currently, literature concerning XIST biology is becoming dominated by miRNA associations and they are also gaining prominence for other lncRNAs produced by the X-inactivation center. This review discusses the available literature to explore possible novel functions related to ceRNA activity of lncRNAs produced by the X-inactivation center, beyond their role in dosage compensation, with prospective implications for emerging gender-biased functions and pathological mechanisms.

lncRNA CYTOR promotes cell proliferation and tumor growth via miR-125b/SEMA4C axis in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a common malignant tumor worldwide with high morbidity and high mortality rates. Previous studies have demonstrated that cytoskeleton regulator RNA (CYTOR) plays critical roles in the tumorigenesis of various types of cancer. The present study aimed to investigate the clinical significance, biological function and molecular mechanism of CYTOR in the progression of HCC. The expression level of CYTOR was determined by reverse transcription quantitative PCR in HCC tissues and cell lines. The biological function of CYTOR was investigated using CCK-8 assay, EdU immunofluorescence, western blotting and TUNEL assay in vitro. A xenograft tumor model and immunohistochemistry were used to validate the role of CYTOR in vivo. The downstream targets of CYTOR and micro-RNA (miR)-125b were confirmed by RNA immunoprecipitation assay and luciferase reporter assays. The results demonstrated that CYTOR was significantly increased in HCC tissues compared with non-tumor tissues and that CYTOR expression was associated with the poor prognosis of patients with HCC. Furthermore, CYTOR silencing could inhibit the proliferation and promote the apoptosis of HCC cells. CYTOR overexpression had the opposite effects. The results from in vivo xenograft demonstrated that CYTOR knockdown suppressed tumor growth. In addition, CYTOR could directly interact with and negatively regulate miR-125b. Furthermore, semaphorin 4C (SEMA4C) was the target of miR-125b and CYTOR regulated SEMA4C expression by modulating miR-125b. Taken together, the findings from the present study demonstrated that CYTOR could promote cell proliferation and tumor growth by sponging miR-125b and upregulating SEMA4C, which suggested that CYTOR may act as a potential therapeutic target in HCC.

Long non-coding RNA XIST accelerates hepatic carcinoma progression by targeting the microRNA-320a/PIK3CA axis

The aim of the present study was to reveal the new molecular mechanism of long non-coding (lnc)RNA XIST in the development of hepatic carcinoma. A total of 69 patients with hepatic carcinoma were included. Hepatoma cell lines (SUN449), hepatoblastoma cell line (HepG2, Huh-6), liver cancer cell line (HepG2) and transformed human liver epithelial-2 cells (THLE-2) were used in the present study. A total 3 short hairpin RNA (sh)-lncRNA XIST sequences, overexpression vector (oe)-lncRNA XIST, microRNA (miR)-320a mimic, miR-320a inhibitor, PIK3CA inhibitor, and their corresponding controls were transfected in hepatic carcinoma cells. Reverse transcription-quantitative polymerase chain reaction was conducted to detect lncRNA-XIST, miR-320a and PIK3CA expression. Cell Counting Kit-8 assay and flow cytometry were undertaken to measure proliferation and apoptosis. Cell invasion and migration were detected by Transwell assays. Moreover, the binding of lncRNA XIST, PIK3CA and miR-320a were verified by luciferase reporter experiment and pull-down assay. Finally, a rescue assay was processed to confirm the effect of lncRNA-XIST, miR-320a and PIK3CA in the aforementioned processes. lncRNA XIST was highly expressed in hepatic carcinoma tissues and cells. The survival rate was significantly lower in the highly expressed lncRNA XIST group. shlncRNA XIST attenuated cell proliferation, invasion and migration, while increasing the apoptosis of hepatic carcinoma cells. The lncRNA XIST negatively targeted miR-320a, and miR-320a negatively regulated the expression of PIK3CA. The miR-320a mimic and PIK3CA inhibitor could recover the effect of oe-lncRNA in terms of the proliferation, invasion, migration and apoptosis of hepatic carcinoma cells. lncRNA XIST accelerates hepatic carcinoma progression by targeting the miR-320a/PIK3CA axis, which might provide the theoretical basis for the potential targeted therapy of hepatic carcinomas.

The Expression of Circulating miR-497 and Metadherin in Hepatocellular Carcinoma: Relation to the Tumor Characteristics and Patients' Survival

Objectives: This study aimed to evaluate the prognostic significance and relationship of miR-497 and metadherin to hepatocellular carcinoma (HCC) tumor characteristics and patients' survival. Methods: This study enrolled 120 (60 HCC patients and 60 healthy) subjects. Serum miR-497 and metadherin mRNA relative expression were analyzed by real-time quantitative reverse transcription polymerase chain reaction. The overall survival (OS) of HCC patients was assessed using the Kaplan-Meier curve and log-rank test. Results: Serum miR-497 showed statistically significant downregulation in HCC patients compared to controls (p < 0.001). Serum metadherin mRNA relative expression was significantly upregulated in HCC patients compared to controls (p < 0.001). Both serum miR-497 and metadherin mRNA expression were significantly associated with the number of tumor foci (p = 0.028 and 0.001, respectively), tumor size (p = 0.022 and <0.001, respectively), nodal metastasis (p = 0.003 and 0.003, respectively), distant metastasis (p = 0.003 and 0.003, respectively), vascular invasion (p = 0.040 and <0.001, respectively), and BCLC staging (p = 0.043 and 0.004, respectively). The overall survival was lower in patients with low miR-497 expression (p = 0.046) and in patients with high metadherin expression (p < 0.001). Conclusions: The expression levels of miR-497 showed downregulation in HCC patients, but metadherin expression showed upregulation. Both markers were inversely related and closely correlated with tumor characteristics and patients' survival.

Identification of prognostic long non-coding RNA signature with potential drugs in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the primary malignancy in the liver with high rate of death and recurrence. Novel prognostic model would be crucial for early diagnosis and improved clinical decision. The study aims to provide an effective lncRNA-based signature to predict survival time and tumor recurrence for HCC. Based on public database, lncRNA-based classifiers for overall survival and tumor recurrence were built with regression analysis and cross validation strategy. According to the risk-score of the classifiers, the whole cohorts were divided into groups with high and low risk. Afterwards, the efficiency of the lncRNA-based classifiers was evaluated and compared with other clinical factors. Finally, candidate small molecules for high risk groups were further screened using drug response databases to explore potential drugs for HCC treatment.

lncRNA MALAT1/miR‑26a/26b/ST8SIA4 axis mediates cell invasion and migration in breast cancer cell lines

Metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) is a long non-coding RNA that is overexpressed in various human cancers, including breast cancer. Evidence has associated the function of the α-2,8-sialyltransferase (ST8SIA) family with breast cancer. The present study aimed to investigate the potential roles of MALAT1 in breast cancer development and progression using analyses of both breast cancer tissues and cell lines. The mRNA levels of MALAT1, microRNA (miR)-26a/26b and ST8SIA4 were detected by reverse transcription-quantitative PCR (RT-qPCR) and the protein level of ST8SIA4 was assessed by western blot analysis. Cell proliferation, invasion and migration were detected by CCK-8, wound healing and Transwell assays, respectively. Interactions between MALAT1 and miR-26a/26b were assessed using fluorescence in situ hybridization, RNA immunoprecipitation and luciferase reporter assays. Herein, different levels of MALAT1 were primarily observed in human breast cancer samples and cells. Upregulated MALAT1 was a crucial predictor of poor breast cancer prognosis. Altered MALAT1 modulated cell progression in breast cancer. Moreover, miR-26a/26b was confirmed as a direct regulator of MALAT1, and ST8SIA4 was predicted as a target of miR-26a/26b. Functional analysis in human breast cancer cell lines demonstrated that MALAT1 modulated breast cancer cell tumorigenicity by acting as a competing endogenous lncRNA (ceRNA) to regulate ST8SIA4 levels by sponging miR-26a/26b. The identification of the MALAT1/miR-26a/26b/ST8SIA4 axis which contributes to breast cancer progression may constitute a potential new therapeutic target.

lncRNA MT1JP-overexpression abolishes the silencing of PTEN by miR-32 in hepatocellular carcinoma

Previous studies have shown that long non-coding RNA (lncRNA) MT1JP plays a role as a tumor suppressor in several types of cancer. The present study aimed to explore the role of MT1JP in hepatocellular carcinoma (HCC). Paired HCC and non-tumor tissues from 64 patients with HCC were subjected to RNA isolation and reverse transcription-quantitative PCR (RT-qPCR) to analyze the differential expression of MT1JP, microRNA (miR)-32 and phosphatase and tensin homolog (PTEN) in HCC. Cell transfections, followed by RT-qPCR and western blotting, were carried out to investigate the interactions among MT1JP, miR-32 and PTEN. The role of MT1JP, miR-32 and PTEN in regulating HCC cell proliferation was assessed using a Cell Counting Kit-8 assay. It was found that MT1JP was downregulated in HCC cancer tissues compared with that in non-cancer tissues. Survival analysis showed that patients with low MT1JP expression levels exhibited a significantly higher 5-year overall survival rate compared with patients with high MT1JP levels. The expression of MT1JP in HCC tissues was positively associated with PTEN and negatively associated with miR-32. Overexpression of MT1JP increased the expression levels of PTEN and decreased the expression levels of miR-32. Overexpression of miR-32 did not affect the expression of MT1JP but decreased the expression levels of PTEN and attenuated the effect of overexpression of MT1JP on the expression of PTEN. Overexpression of MT1JP and PTEN decreased the proliferation of HCC cells. Overexpression of miR-32 played an opposite role and attenuated the effects of overexpression of MT1JP. Therefore, MT1JP may upregulate PTEN by downregulating miR-32 to regulate HCC cell proliferation.

X-Inactive-Specific Transcript: Review of Its Functions in the Carcinogenesis

X-inactive-specific transcript (XIST) is one of the firstly discovered long non-coding RNAs with prominent roles in the process of X inactivation. Moreover, this transcript contributes in the carcinogenic process in different tissues. In addition to interacting with chromatin modifying molecules, XIST can be served as a molecular sponge for miRNAs to modulate expression of miRNA targets. Most of the studies have indicated an oncogenic role for XIST. However, in prostate cancer, a single study has indicated a tumor suppressor role for this lncRNA. Similar result has been reported for XIST in oral squamous cell carcinoma. In hepatocellular carcinoma, breast cancer, ovarian cancer, osteosarcoma, and renal cell carcinoma, different studies have reported inconsistent results. In the present manuscript, we review function of XIST in the carcinogenesis.

Biological Function of Long Non-coding RNA (LncRNA) Xist

Long non-coding RNAs (lncRNAs) regulate gene expression in a variety of ways at epigenetic, chromatin remodeling, transcriptional, and translational levels. Accumulating evidence suggests that lncRNA X-inactive specific transcript (lncRNA Xist) serves as an important regulator of cell growth and development. Despites its original roles in X-chromosome dosage compensation, lncRNA Xist also participates in the development of tumor and other human diseases by functioning as a competing endogenous RNA (ceRNA). In this review, we comprehensively summarized recent progress in understanding the cellular functions of lncRNA Xist in mammalian cells and discussed current knowledge regarding the ceRNA network of lncRNA Xist in various diseases. Long non-coding RNAs (lncRNAs) are transcripts that are more than 200 nt in length and without an apparent protein-coding capacity (Furlan and Rougeulle, 2016; Maduro et al., 2016). These RNAs are believed to be transcribed by the approximately 98-99% non-coding regions of the human genome (Derrien et al., 2012; Fu, 2014; Montalbano et al., 2017; Slack and Chinnaiyan, 2019), as well as a large variety of genomic regions, such as exonic, tronic, and intergenic regions. Hence, lncRNAs are also divided into eight categories: Intergenic lncRNAs, Intronic lncRNAs, Enhancer lncRNAs, Promoter lncRNAs, Natural antisense/sense lncRNAs, Small nucleolar RNA-ended lncRNAs (sno-lncRNAs), Bidirectional lncRNAs, and non-poly(A) lncRNAs (Ma et al., 2013; Devaux et al., 2015; St Laurent et al., 2015; Chen, 2016; Quinn and Chang, 2016; Richard and Eichhorn, 2018; Connerty et al., 2020). A range of evidence has suggested that lncRNAs function as key regulators in crucial cellular functions, including proliferation, differentiation, apoptosis, migration, and invasion, by regulating the expression level of target genes via epigenomic, transcriptional, or post-transcriptional approaches (Cao et al., 2018). Moreover, lncRNAs detected in body fluids were also believed to serve as potential biomarkers for the diagnosis, prognosis, and monitoring of disease progression, and act as novel and potential drug targets for therapeutic exploitation in human disease (Jiang W. et al., 2018; Zhou et al., 2019a). Long non-coding RNA X-inactive specific transcript (lncRNA Xist) are a set of 15,000-20,000 nt sequences localized in the X chromosome inactivation center (XIC) of chromosome Xq13.2 (Brown et al., 1992; Debrand et al., 1998; Kay, 1998; Lee et al., 2013; da Rocha and Heard, 2017; Yang Z. et al., 2018; Brockdorff, 2019). Previous studies have indicated that lncRNA Xist regulate X chromosome inactivation (XCI), resulting in the inheritable silencing of one of the X-chromosomes during female cell development. Also, it serves a vital regulatory function in the whole spectrum of human disease (notably cancer) and can be used as a novel diagnostic and prognostic biomarker and as a potential therapeutic target for human disease in the clinic (Liu et al., 2018b; Deng et al., 2019; Dinescu et al., 2019; Mutzel and Schulz, 2020; Patrat et al., 2020; Wang et al., 2020a). In particular, lncRNA Xist have been demonstrated to be involved in the development of multiple types of tumors including brain tumor, Leukemia, lung cancer, breast cancer, and liver cancer, with the prominent examples outlined in Table 1. It was also believed that lncRNA Xist (Chaligne and Heard, 2014; Yang Z. et al., 2018) contributed to other diseases, such as pulmonary fibrosis, inflammation, neuropathic pain, cardiomyocyte hypertrophy, and osteoarthritis chondrocytes, and more specific details can be found in Table 2. This review summarizes the current knowledge on the regulatory mechanisms of lncRNA Xist on both chromosome dosage compensation and pathogenesis (especially cancer) processes, with a focus on the regulatory network of lncRNA Xist in human disease.

LncRNA XIST serves as a diagnostic biomarker in gestational diabetes mellitus and its regulatory effect on trophoblast cell via miR-497-5p/FOXO1 axis

Background

Gestational diabetes mellitus (GDM) is increasingly common in pregnancy. This study's purpose was to identify the expression of XIST and manifest the potential mechanism of XIST in GDM.

Methods

Ninety-three patients with GDM and 93 normal pregnant women were included in this investigation. qRT-PCR was conducted to evaluate the expression of miR-497-5p and XIST and the relationship between XIST and fasting blood glucose (FBG) was explored by Pearson assay. The clinical diagnosis of XIST on GDM patients was validated by the receiver operator characteristic (ROC) curve. Cell counting kit-8 (CCK-8) was applied to elucidate cell viability. Luciferase reporter assay was performed to document the relationship among XIST, miR-497-5p, and FOXO1.

Results

The expression of XIST was increased in GDM patients and HTR-8/SVneo cell models caused by high glucose (HG). The expression of XIST was associated with the FBG levels and appeared to be a feasible indicator in discriminating GDM patients. The expression of miR-497-5p was prominently reduced in GDM patients and cell models. Inhibition of XIST might alleviate the adverse function of HG on cell viability via sponging miR-497-5p. FOXO1 was proved to be a downstream target gene of miR-497-5p.

Conclusions

Overexpression of XIST and downregulation of miR-497-5p were indicated in this publication. XIST might serve as a promising diagnostic marker for GDM patients. XIST/miR-497-5p/FOXO1 axis played a critical role in the regulation of trophoblast cells.

Genome-Wide Screening Identifies Prognostic Long Noncoding RNAs in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is a common malignancy with a poor prognosis. Therefore, there is an urgent call for the investigation of novel biomarkers in HCC. In the present study, we identified 6 upregulated lncRNAs in HCC, including LINC01134, RHPN1-AS1, NRAV, CMB9-22P13.1, MKLN1-AS, and MAPKAPK5-AS1. Higher expression of these lncRNAs was correlated to a more advanced cancer stage and a poorer prognosis in HCC patients. Enrichment analysis revealed that these lncRNAs played a crucial role in HCC progression, possibly through a series of cancer-related biological processes, such as cell cycle, DNA replication, histone acetyltransferase complex, fatty acid oxidation, and lipid modification. Moreover, competing endogenous RNA (ceRNA) network analysis revealed that these lncRNAs could bind to certain miRNAs to promote HCC progression. Loss-of-function assays indicated that silencing of RHPN1-AS1 significantly suppressed HCC proliferation and migration. Though further validations are still needed, these identified lncRNAs could serve as valuable potential biomarkers for HCC prognosis.

Comprehensive analyses of competing endogenous RNA networks reveal potential biomarkers for predicting hepatocellular carcinoma recurrence

Background

Hepatocellular carcinoma (HCC) is one of the most common and deadly malignant tumors, with a high rate of recurrence worldwide. This study aimed to investigate the mechanism underlying the progression of HCC and to identify recurrence-related biomarkers.

Methods

We first analyzed 132 HCC patients with paired tumor and adjacent normal tissue samples from the Gene Expression Omnibus (GEO) database to identify differentially expressed genes (DEGs). The expression profiles and clinical information of 372 HCC patients from The Cancer Genome Atlas (TCGA) database were next analyzed to further validate the DEGs, construct competing endogenous RNA (ceRNA) networks and discover the prognostic genes associated with recurrence. Finally, several recurrence-related genes were evaluated in two external cohorts, consisting of fifty-two and forty-nine HCC patients, respectively.

Results

With the comprehensive strategies of data mining, two potential interactive ceRNA networks were constructed based on the competitive relationships of the ceRNA hypothesis. The ‘upregulated’ ceRNA network consists of 6 upregulated lncRNAs, 3 downregulated miRNAs and 5 upregulated mRNAs, and the ‘downregulated’ network includes 4 downregulated lncRNAs, 12 upregulated miRNAs and 67 downregulated mRNAs. Survival analysis of the genes in the ceRNA networks demonstrated that 20 mRNAs were significantly associated with recurrence-free survival (RFS). Based on the prognostic mRNAs, a four-gene signature (ADH4, DNASE1L3, HGFAC and MELK) was established with the least absolute shrinkage and selection operator (LASSO) algorithm to predict the RFS of HCC patients, the performance of which was evaluated by receiver operating characteristic curves. The signature was also validated in two external cohort and displayed effective discrimination and prediction for the RFS of HCC patients.

Conclusions

In conclusion, the present study elucidated the underlying mechanisms of tumorigenesis and progression, provided two visualized ceRNA networks and successfully identified several potential biomarkers for HCC recurrence prediction and targeted therapies.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-021-08173-0.

MicroRNA-183-5p contributes to malignant progression through targeting PDCD4 in human hepatocellular carcinoma

Hepatocellular carcinoma (HCC) remains one of the most common malignant tumors worldwide. The present study aimed to investigate the biological role of microRNA-183-5p (miR-183-5p), a novel tumor-related microRNA (miRNA), in HCC and illuminate the possible molecular mechanisms. The expression patterns of miR-183-5p in clinical samples were characterized using qPCR analysis. Kaplan–Meier survival curve was applied to evaluate the correlation between miR-183-5p expression and overall survival of HCC patients. Effects of miR-183-5p knockdown on HCC cell proliferation, apoptosis, migration and invasion capabilities were determined via Cell Counting Kit-8 (CCK8) assays, flow cytometry, scratch wound healing assays and Transwell invasion assays, respectively. Mouse neoplasm transplantation models were established to assess the effects of miR-183-5p knockdown on tumor growth in vivo. Bioinformatics analysis, dual-luciferase reporter assays and rescue assays were performed for mechanistic researches. Results showed that miR-183-5p was highly expressed in tumorous tissues compared with adjacent normal tissues. Elevated miR-183-5p expression correlated with shorter overall survival of HCC patients. Moreover, miR-183-5p knockdown significantly suppressed proliferation, survival, migration and invasion of HCC cells compared with negative control treatment. Consistently, miR-183-5p knockdown restrained tumor growth in vivo. Furthermore, programmed cell death factor 4 (PDCD4) was identified as a direct target of miR-183-5p. Additionally, PDCD4 down-regulation was observed to abrogate the inhibitory effects of miR-183-5p knockdown on malignant phenotypes of HCC cells. Collectively, our data suggest that miR-183-5p may exert an oncogenic role in HCC through directly targeting PDCD4. The current study may offer some new insights into understanding the role of miR-183-5p in HCC.

MicroRNA-497-5p Is Downregulated in Hepatocellular Carcinoma and Associated with Tumorigenesis and Poor Prognosis in Patients

Background

MicroRNAs (miRNAs) have been demonstrated to exhibit important regulatory roles in multiple malignancies, including hepatocellular carcinoma (HCC). hsa-miR-497-5p was reported to involve in cancer progression and poor prognosis in many kinds of tumors. However, the expression and its clinical significance of hsa-miR-497-5p in HCC remain unclear.

Methods

In the present study, we investigated the expression of hsa-miR-497-5p in HCC and analyzed the correction of clinical features with prognosis. The expression levels of hsa-miR-497-5p and potential target genes were analyzed in HCC and adjacent noncancerous tissues using The Cancer Genome Atlas (TCGA) database and Gene Expression Omnibus (GEO) datasets. Real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR) was used to analyze hsa-miR-497-5p levels in 328 HCC tissues and 30 paired adjacent noncancer tissues. Overall survival (OS) and progression-free survival (PFS) of patients with HCC were assessed using the Kaplan-Meier method and the log-rank test.

Results

The hsa-miR-497-5p expression levels were decreased, and its target genes ACTG1, CSNK1D, PPP1CC, and BIRC5 were upregulated in HCC tissues compared with normal tissues. Lower levels of hsa-miR-497-5p expression and higher levels of the four target genes were significantly associated with higher tumor diameter. Moreover, patients with lower hsa-miR-497-5p expression and higher target genes levels had shorter OS.

Conclusion

The expression levels of hsa-miR-497-5p may play an important regulatory role in HCC and are closely correlated with HCC progression and poor prognosis in patients. The hsa-miR-497-5p may be a specific therapeutic target for the treatment of HCC.

LncRNA-SNHG6 promotes the progression of hepatocellular carcinoma by targeting miR-6509-5p and HIF1A

Background

Accumulating evidences have been reported that long noncoding RNAs play crucial roles in the progression of hepatocellular carcinoma (HCC). SnoRNA host gene 6 (SNHG6) is believed to be involved in several human cancers, but the specific molecular mechanism of SNHG6 in HCC is not well studied.

Methods

In this study, we experimentally down-regulated the SNHG6 in two hepatocellular carcinoma cell lines in vitro, and then measured the proliferation, migration and invasion abilities and the apoptotic levels. Also, we performed the xenograft assay to investigate the function of SNHG6 during the tumor growth in vivo.

Results

We found SNHG6 was highly expressed in HCC tissues. Next, using Hep3B and Huh7 cells, we confirmed knockdown of SNHG6 reduced the proliferation, migration and invasion abilities in vitro. Also, by bioinformatics analysis, further molecular and cellular experiments, we found miR-6509-5p bound to SNHG6 directly, and the expression level of HIF1A was regulated through SNHG6/miR-6509-5p axis. Finally, we found that down-regulation of SNHG6 dramatically reduced the tumor growth ability of Huh7 cells in vivo.

Conclusions

We concluded that SNHG6/miR-6509-5p/HIF1A axis functioned in the progression of hepatocellular carcinoma, and could be the promising therapeutic targets during the development of hepatocellular carcinoma drugs.

Regulatory Effect of miR497-5p-CCNE1 Axis in Triple-Negative Breast Cancer Cells and Its Predictive Value for Early Diagnosis

OBJECTIVE

To explore the regulatory role of miR497-5p-CCNE1 axis in triple-negative breast cancer (TNBC) cells and its predictive value for early diagnosis.

METHODS

Cancer tissue and adjacent tissue samples were collected from 86 patients with TNBC.RT-PCR was used to detect the expression of miR497-5p and CCNE1 (target gene) mRNA, determined by biological prediction in tissue and TNBC cells. ROC was used to analyze the diagnostic value of miR497-5p in TNBC. MTT, invasion, and flow cytometry were used to detect the proliferation, invasion, cycle, apoptosis rate, and expression of related proteins of TNBC cells with overexpression of miR497-5p or knockdown of CCNE1.

RESULTS

RT-qPCR results showed that miR497-5p levels were significantly downregulated in TNBC tissue and cells, while CCNE1 expression was significantly upregulated, and miR497-5p expression was negatively correlated with that of CCNE1 (P<0.001). ROC analysis showed that the AUC of miR497-5p for TNBC was >0.9, which had better diagnostic value. The cell tests revealed that miR497-5p played a role in tumor inhibition, including inhibiting proliferation and invasion of TNBC cells, blocking the cell cycle, and promoting apoptosis. Bioinformatic prediction and subsequent experiments revealed that CCNE1 was the direct target of miR497-5p. Furthermore, after knocking down the expression of CCNE1 in TNBC cells, the proliferation and invasion of TNBC cells were significantly inhibited, the cell cycle blocked, and the apoptosis rate significantly increased (P<0.001), and expression of the proapoptosis-related proteins Bax and caspase 3 (cleaved) were upregulated, while expression of the antiapoptosis-related protein BCL2 was downregulated (P<0.001).

CONCLUSION

miR497-5p inhibited the proliferation and invasion of TNBC cells by targeting CCNE1, blocked the cell cycle and promoted the apoptosis of TNBC cells, and had better diagnostic value for TNBC. miR497-5p can be used as a new potential target for the treatment of TNBC.

DLG1-AS1 is activated by MYC and drives the proliferation and migration of hepatocellular carcinoma cells through miR-497-5p/SSRP1 axis

Background

Long non-coding RNAs (lncRNAs) have been reported to be biological regulators in hepatocellular carcinoma (HCC). DLG1 antisense RNA 1 (DLG1-AS1) has been found to be up-regulated in cervical cancer. However, its function and underlying mechanism in HCC remains unknown.

Methods

DLG1-AS1 expression was assessed in HCC cells and normal cell by RT-qPCR. Luciferase reporter assay, RNA pull down assay and RIP assay were used to demonstrate the interaction between DLG1-AS1 and miR-497-5p.

Results

DLG1-AS1 was highly expressed in HCC cells. Silencing of DLG1-AS1 led to the inhibition of HCC cell growth and migration. Besides, MYC induced the transcriptional activation of DLG1-AS1. MYC could facilitate HCC cellular processes by up-regulating DLG1-AS1. MiR-497-5p could interact with DLG1-AS1 in HCC cells. Down-regulation of miR-497-5p could reverse the impacts of DLG1-AS1 silencing on HCC cells. SSRP1 expression could be positively regulated by DLG1-AS1 but was negatively regulated by miR-497-5p. Knockdown of DLG1-AS1 suppressed tumor growth in nude mice.

Conclusions

DLG1-AS1 is activated by MYC and functions as an oncogene in HCC via miR-497-5p/SSRP1 axis.

Upregulation of tissue long noncoding RNA X inactive specific transcript predicts poor postoperative survival in patients with non-small cell lung cancer

X inactive specific transcript (XIST) is a novel long noncoding RNA (lncRNA) which has been reported to be frequently upregulated in various human cancer types and to function as an oncogene. It has been reported that the expression of lncRNA XIST was upregulated in non-small cell lung cancer (NSCLC). In the present study, we aimed to investigate the clinical significance and prognostic value of XIST in patients with NSCLC.A total of 156 pairs of NSCLC and corresponding adjacent normal lung tissue samples were obtained from NSCLC patients who had undergone surgery from July 2014 to March 2019. The Student's t test was used in different treated groups for statistical analysis. The association between XIST expression and clinicopathological features of NSCLC patients was evaluated using the chi-squared test. Survival curves were plotted using Kaplan-Meier method and compared by log-rank test.The expression of XIST was significantly higher in NSCLC samples compared to non-cancerous samples (P < .001). Statistically significant correlations were observed between high tissue XIST expression level and lymph node metastasis (P = .036) and high Tumor Node Metastasis (TNM) stage (P = .002). The log-rank test indicated that patients with increased XIST expression experienced poor overall survival (P = .006). Multivariate Cox regression analysis showed that XIST expression level (hazard ratio = 2.645, 95% confidence interval: 1.672-7.393, P = .029) was an independent factors in predicting the overall survival of NSCLC patients.The present study found that XIST expression level was significantly associated with advanced pathological stage and high TNM stage in NSCLC. Furthermore, upregulation of tissue lncRNA XIST predicts poor postoperative survival in patients with NSCLC.

lncRNA-Xist/miR-101-3p/KLF6/C/EBPα axis promotes TAM polarization to regulate cancer cell proliferation and migration

The phenotypic switch in tumor-associated macrophages (TAMs) mediates immunity escape of cancer. However, the underlying mechanisms in the TAM phenotypic switch have not been systematically elucidated. In this study, long noncoding RNA (lncRNA)-Xist, CCAAT/enhancer-binding protein (C/EBP)α, and Kruppel-like factor 6 (KLF6) were upregulated, whereas microRNA (miR)-101 was downregulated in M1 macrophages-type (M1). Knockdown of Xist or overexpression of miR-101 in M1 could induce M1-to-M2 macrophage-type (M2) conversion to promote cell proliferation and migration of breast and ovarian cancer by inhibiting C/EBPα and KLF6 expression. Furthermore, miR-101 could combine with both Xist and C/EBPα and KLF6 through the same microRNA response element (MRE) predicted by bioinformatics and verified by luciferase reporter assays. Moreover, we found that miR-101 knockdown restored the decreased M1 marker and the increased M2 marker expression and also reversed the promotion of proliferation and migration of human breast cancer cells (MCF-7) and human ovarian cancer (OV) cells caused by silencing Xist. Generally, the present study indicates that Xist could mediate macrophage polarization to affect cell proliferation and migration of breast and ovarian cancer by competing with miR-101 to regulate C/EBPα and KLF6 expression. The promotion of Xist expression in M1 macrophages and inhibition of miR-101 expression in M2 macrophages might play an important role in inhibiting breast and ovarian tumor proliferation and migration abilities.

Long Non-coding RNA X-Inactive Specific Transcript Mediates Cell Proliferation and Intrusion by Modulating the miR-497/Bcl-w Axis in Extranodal Natural Killer/T-cell Lymphoma

The present study was directed toward laying new findings for Extranodal natural killer/T-cell lymphoma (ENKL)-oriented therapy with a focus on long non-coding RNA (lncRNA)–microRNAs (miRNAs)–mRNA interaction. The expression and function of XIST (X-inactive specific transcript) were analyzed both in vivo and in vitro. The online database of lncRNA-miRNA interaction was used to screen the target of XIST, and miR-497 was selected. Next, the predicted binding between XIST and miR-497, and the dynamic effect of XIST and miR-497 on downstream Bcl-w was evaluated. We found that XIST dramatically increased in the blood of ENKL patients and cell lines. XIST knockdown suppressed the cell proliferation and migration in vivo and in vitro. Herein, we confirmed the negative interaction between XIST and miR-497. Moreover, XIST knockdown reduced the protein levels of Bcl-w, a downstream target of miR-497. XIST sponges miR-497 to promote Bcl-w expression, and finally modulating ENKL cell proliferation and migration. To be interested, inhibition of Bcl-w by ABT737 can overcome the high expression of XIST, and suppressed the ENKL proliferation and migration by inducing apoptosis. This study provided a novel experimental basis for ENKL-oriented therapy with a focus on the lncRNA–miRNA–mRNA interaction.

Regulation of microRNA-497 expression in human cancer

MicroRNAs (miRNAs/miRs) are a type of non-coding single-stranded RNA, with a length of ~22 nt, which are encoded by endogenous genes and are involved in the post-transcriptional regulation of gene expression in animals and plants. Studies have demonstrated that miRNAs play an important role in the occurrence, development, metastasis, diagnosis and treatment of cancer. In recent years, miR-497 has been identified as one of the key miRNAs in a variety of cancer types and has been shown to be downregulated in a variety of solid tumors. However, the regulation of miR-497 expression involves a complex network, which is affected by several factors. The aim of the present review was to summarize the mechanism of regulation of miR-497 expression at the pre-transcriptional and transcriptional levels in cancer, as well as the role of miR-497 expression imbalance in cancer diagnosis, treatment and prognosis. The regulatory mechanisms of miR-497 expression may aid in our understanding of the causes of miR-497 expression imbalance and provide a reference value for further research on the diagnosis and treatment of cancer.

MicroRNA: Promising Roles in Cancer Therapy

MicroRNAs (miRNA) are small non-coding RNAs that act as one of the main regulators of gene expression. They are involved in maintaining a proper balance of diverse processes, including differentiation, proliferation, and cell death in normal cells. Cancer biology can also be affected by these molecules by modulating the expression of oncogenes or tumor suppressor genes. Thus, miRNA based anticancer therapy is currently being developed either alone or in combination with chemotherapy agents used in cancer management, aiming at promoting tumor regression and increasing cure rate. Access to large quantities of RNA agents can facilitate RNA research and development. In addition to currently used in vitro methods, fermentation-based approaches have recently been developed, which can cost-effectively produce biological RNA agents with proper folding needed for the development of RNA-based therapeutics. Nevertheless, a major challenge in translating preclinical studies to clinical for miRNA-based cancer therapy is the efficient delivery of these agents to target cells. Targeting miRNAs/anti-miRNAs using antibodies and/or peptides can minimize cellular and systemic toxicity. Here, we provide a brief review of miRNA in the following aspects: biogenesis and mechanism of action of miRNAs, the role of miRNAs in cancer as tumor suppressors or oncogenes, the potential of using miRNAs as novel and promising therapeutics, miRNA-mediated chemo-sensitization, and currently utilized methods for the in vitro and in vivo production of RNA agents. Finally, an update on the viral and non-viral delivery systems is addressed.

Programmed cell death factor 4 (PDCD4), a novel therapy target for metabolic diseases besides cancer

Programmed cell death factor 4 (PDCD4) is originally described as a tumor suppressor gene that exerts antineoplastic effects by promoting apoptosis and inhibiting tumor cell proliferation, invasion, and metastasis. Several investigations have probed the aberrant expression of PDCD4 with the progression of metabolic diseases, such as polycystic ovary syndrome (PCOS), obesity, diabetes, and atherosclerosis. It has been ascertained that PDCD4 causes glucose and lipid metabolism disorders, insulin resistance, oxidative stress, chronic inflammatory response, and gut flora disorders to regulate the progression of metabolic diseases. This review aims to summarize the latest researches to uncover the structure, expression regulation, and biological functions of PDCD4 and to elucidate the regulatory mechanism of the development of tumors and metabolic diseases. This review has emphasized the understanding of the PDCD4 role and to provide new ideas for the research, diagnosis, and treatment of tumors and metabolic diseases.

The emerging roles of non-coding competing endogenous RNA in hepatocellular carcinoma

Accumulating evidence has emerged revealing that noncoding RNAs (ncRNAs) play essential roles in the occurrence and development of hepatocellular carcinoma (HCC). However, the complicated regulatory interactions among various ncRNAs in the development of HCC are not entirely understood. The newly discovered mechanism of competing endogenous RNAs (ceRNAs) uncovered regulatory interactions among different varieties of RNAs. In recent years, a growing number of studies have suggested that ncRNAs, including long ncRNAs, circular RNAs and pseudogenes, play major roles in the biological functions of the ceRNA network in HCC. These ncRNAs can share microRNA response elements to affect microRNA affinity with target RNAs, thus regulating gene expression at the transcriptional level and both physiological and pathological processes. The ncRNAs that function as ceRNAs are involved in diverse biological processes in HCC cells, such as tumor cell proliferation, epithelial-mesenchymal transition, invasion, metastasis and chemoresistance. Based on these findings, ncRNAs that act as ceRNAs may be promising candidates for clinical diagnosis and treatments. In this review, we discuss the mechanisms and research methods of ceRNA networks. We also reviewed the recent advances in studying the roles of ncRNAs as ceRNAs in HCC and highlight possible directions and possibilities of ceRNAs as diagnostic biomarkers or therapeutic targets. Finally, the limitations, gaps in knowledge and opportunities for future research are also discussed.

AZIN1-AS1, A Novel Oncogenic LncRNA, Promotes the Progression of Non-Small Cell Lung Cancer by Regulating MiR-513b-5p and DUSP11

Background

Emerging researches have demonstrated that aberrantly expressed long non-coding RNAs (lncRNAs) have great significance in non-small cell lung cancer (NSCLC) progression. The aim of this study was to explore the role of lncRNA AZIN1 antisense RNA 1 (AZIN1-AS1) in NSCLC and the related mechanism.

Methods

Expressions of AZIN1-AS1 and miR-513b-5p in NSCLC samples were detected by qRT-PCR. NSCLC cell lines (H1299 and HCC827) were used in vitro assays. CCK-8 assay, EdU assay, wound healing test and Transwell assay were carried out to test the biological influence of AZIN1-AS1 on NSCLC cells. Subcutaneous xenotransplanted tumor model and tail vein injection model were established to test the role of AZIN1-AS1 in vivo. Interactions between AZIN1-AS1 and miR-513b-5p, miR-513b-5p and dual-specificity phosphatase 11 (DUSP11) were determined by bioinformatic analysis, qRT-PCR, Western blot, and luciferase reporter assay.

Results

AZIN1-AS1 was up-regulated in NSCLC cells and tissues, while miR-513b-5p was significantly down-regulated. Silencing of AZIN1-AS1 or overexpression of miR-513b-5p markedly inhibited proliferation, migration and invasion of NSCLC cells, while overexpression of AZIN1-AS1 or inhibition of miR-513b-5p functioned oppositely. Importantly, AZIN1-AS1 mediated the promotion of malignancy of NSCLC cells was reversed by miR-513b-5p mimics. What’s more, AZIN1-AS1 could down-regulate miR-513b-5p via sponging it, and there existed a negative correlation between AZIN1-AS1 expression and miR-513b-5p expression in NSCLC samples. AZIN1-AS1 also enhanced the expression levels of DUSP11, which was proved as a target gene of miR-513b-5p. Further in vivo experiments showed that silencing of AZIN1-AS1 decreased tumor growth and metastasis, which was accompanied by overexpression of miR-513b-5p and inhibition of DUSP11 in tumor tissues.

Conclusion

AZIN1-AS1 acts as a tumor promoter in NSCLC, which is ascribed to the regulation of miR-513b-5p and DUSP11.

Epigenetic Associations between lncRNA/circRNA and miRNA in Hepatocellular Carcinoma

Simple Summary

Non-coding RNAs such as microRNAs, long non-coding RNAs, and circular RNAs contribute to the development and progression of hepatocellular carcinoma through epigenetic association. Long non-coding RNAs and circular RNAs act as competing endogenous RNAs that contain binding sites for miRNAs and thus compete with the miRNAs, which results in promotion of miRNA target gene expression, thereby leading to proliferation and metastasis of hepatocellular carcinoma. Competing endogenous RNAs have the potential to become diagnostic biomarkers and therapeutic targets for treatment of hepatocellular carcinoma.

Abstract

The three major members of non-coding RNAs (ncRNAs), named microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs), play an important role in hepatocellular carcinoma (HCC) development. Recently, the competing endogenous RNA (ceRNA) regulation model described lncRNA/circRNA as a sponge for miRNAs to indirectly regulate miRNA downstream target genes. Accumulating evidence has indicated that ceRNA regulatory networks are associated with biological processes in HCC, including cancer cell growth, epithelial to mesenchymal transition (EMT), metastasis, and chemoresistance. In this review, we summarize recent discoveries, which are specific ceRNA regulatory networks (lncRNA/circRNA-miRNA-mRNA) in HCC and discuss their clinical significance.

LncRNA RHPN1-AS1 Promotes Cell Proliferation, Migration and Invasion Through Targeting miR-7-5p and Activating PI3K/AKT/mTOR Pathway in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is a severe disease with high mortality in the world. Emerging evidence has suggested that lncRNAs play an important role in cancer progression, including HCC. This study aimed to comprehensively investigate the effect of lncRNA RHPN1 antisense RNA 1 (RHPN1-AS1) on HCC and its underlying molecular mechanism. In this study, we evaluated the expressions of lncRNA RHPN1-AS1 and miR-7-5p by qRT-RCR in both HCC tissue and HCC cells. Our findings showed that lncRNA RHPN1-AS1 was upregulated in HCC tissue and HCC cells, while miR-7-5p was downregulated. LncRNA RHPN1-AS1 expression in HCC patients was closely related to vascular invasion, tumor-node-metastasis (TNM) stage and barcelona clinic liver cancer (BCLC) stage. Furthermore, we quantified cell clone-formation ability, proliferation, migration and invasion of HCCLM3 and MHCC97 H cells using several assays (colony formation assay, 5-Ethynyl-2′-deoxyuridine (EdU) assay and transwell assay, respectively). Functional experiments confirmed that silencing lncRNA RHPN1-AS1 inhibited cell proliferation, migration and invasion in HCCLM3 and MHCC97 H cells. After that, bioinformatics analysis, dual luciferase reporter gene assay, qRT-PCR and western blot were used to investigate the molecular mechanism of lncRNA RHPN1-AS1 on HCC. Mechanistically, the rescue experiments demonstrated that miR-7-5p inhibitor reversed the inhibition effect of silencing lncRNA RHPN1-AS1 on HCCLM3 cells proliferation, migration and invasion. Moreover, silencing lncRNA RHPN1-AS1 also inhibited the activation of PI3K/AKT/mTOR pathway. Taken together our findings demonstrated that lncRNA RHPN1-AS1 could facilitate cell proliferation, migration and invasion via targeting miR-7-5p and activating PI3K/AKT/mTOR pathway in HCC.

LINC00657 promotes colorectal cancer stem-like cell invasion by functioning as a miR-203a sponge

Recently, the role of long non-coding RNAs (lncRNAs) in regulating multiple cancer types has attracted increasing interest because of their involvement in cell metastasis in different cancer types. Previous studies indicated that LINC00657 may work as an oncogene in gastric and colon cancer. However, the functional role and mechanistic action of LINC00657 on colorectal cancer (CRC) remains unknown. Therefore, in this study, the role of LINC00657 in CRC was evaluated. Our results showed that LINC00657 was enriched in CRC stem-like cells (CSCs) and significantly promoted CSCs invasion ability. LINC00657 expression resulted frequently up-regulated in CRC patient tissue, and high expression of LINC00657 was correlated with an advanced clinical stage, lymph node metastasis, distant metastasis and poor overall survival of CRC patients. Furthermore, LINC00657 worked as a competing endogenous RNA (ceRNA) for miR-203a, antagonizing its function as a tumor suppressor and leading to the de-repression of CSCs invasion. Collectively, our observations revealed that LINC00657 is involved in CRC invasion by acting as a competing endogenous RNA. Thus, LINC00657 may serve as a potential prognostic factor and/or therapeutic target for CRC.

Long noncoding RNA LINC00324 promotes retinoblastoma progression by acting as a competing endogenous RNA for microRNA-769-5p, thereby increasing STAT3 expression

Long intergenic non–protein-coding RNA 324 (LINC00324) is abnormally expressed in multiple human cancer types and plays an important role in cancer initiation and progression. This study showed that LINC00324 was expressed at higher levels in retinoblastoma (RB) tumors and cell lines than in control samples. Increased LINC00324 expression closely correlated with the TNM stage, optic nerve invasion, and shorter overall survival among patients with RB. The knockdown of LINC00324 decreased RB cell proliferation, colony formation, migration, and invasion, and promoted apoptosis and cell cycle arrest in vitro as well as hindered tumor growth in vivo. With respect to the mechanism, LINC00324 acted as a competing endogenous RNA for microRNA-769-5p (miR-769-5p) in RB cells. The mRNA of signal transducer and activator of transcription 3 (STAT3) was identified as a direct target of miR-769-5p in RB cells. Rescue experiments indicated that restoration of STAT3 expression attenuated the tumor-suppressive actions of miR-769-5p in RB cells. Downregulation of miR-769-5p or restoration of STAT3 almost completely reversed the effects of LINC00324 knockdown on RB cells. Our findings describe a novel RB-related LINC00324–miR-769-5p–STAT3 axis that is implicated in the malignancy of RB in vitro and in vivo. This study may point to innovative therapeutic targets in RB.

Research progress on the interactions between long non-coding RNAs and microRNAs in human cancer

Numerous types of molecular mechanisms mediate the development of cancer. Non-coding RNAs (ncRNAs) are being increasingly recognized to play important role in mediating the development of diseases, including cancer. Long non-coding RNAs (lncRNAs) and microRNAs (miRNAs) are the two most widely studied ncRNAs. Thus far, lncRNAs are known to have biological roles through a variety of mechanisms, including genetic imprinting, chromatin remodeling, cell cycle control, splicing regulation, mRNA decay and translational regulation, and miRNAs regulate gene expression through the degradation of mRNAs and lncRNAs. Although ncRNAs account for a major proportion of the total RNA, the mechanisms underlying the physiological or pathological processes mediated by various types of ncRNAs, and the specific interaction mechanisms between miRNAs and lncRNAs in various physiological and pathological processes, remain largely unknown. Thus, further research in this field is required. In general, the interaction mechanisms between miRNAs and lncRNAs in human cancer have become important research topics, and the study thereof has led to the recent development of related technologies. By providing examples and descriptions, and performing chart analysis, the present study aimed to review the interaction mechanisms and research approaches for these two types of ncRNAs, as well as their roles in the occurrence and development of cancer. These details have far-reaching significance for the utilization of these molecules in the diagnosis and treatment of cancer.

Role of miRNA sponges in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a leading cause of cancer-related deaths worldwide. HCC patients are commonly diagnosed at an advanced stage, for which highly effective therapies are limited. Hence, there is a growing need to discover promising biomarkers for HCC diagnosis, and in this context, microRNAs (miRNAs) hold great promise. MiRNAs function as gene expression regulators by directly binding messenger RNAs (mRNAs) and subsequently causing suppression of mRNA translation or degradation of target mRNAs. Two major types of noncoding RNAs act as competing endogenous sponges: circular RNAs and long non-coding RNAs.They can competitively bind to miRNA through miRNA response elements (MREs), thereby reducing the number of miRNAs binding mRNAs and regulating the expression of downstream target genes of miRNAs at the posttranscriptional level. The relationship between single miRNA sponge and HCC has been explored. However, comprehensive reviews on the sponge's function in HCC are lacking. In this review, we describe the methods to find endogenous sponges and construct exogenous sponges, and briefly compare endogenous and exogenous sponges. We also summarize the current progress on the functional role of miRNA sponges in HCC pathogenesis and present their potential value as diagnostic biomarkers and therapeutic targets. In-depth investigations on the function and mechanism of miRNA sponges in HCC will enrich our knowledge of HCC pathogenesis and contribute to the development of effective diagnostic biomarkers and therapeutic targets for HCC.