Long noncoding RNA Linc00339 promotes triple‐negative breast cancer progression through miR‐377‐3p/HOXC6 signaling pathway

Circ_0004676 exacerbates triple-negative breast cancer progression through regulation of the miR-377-3p/E2F6/PNO1 axis

BACKGROUND

The significant roles of circular RNAs (circRNAs) in different cancers and diseases have been reported. We now focused on the possible role of a newly recognized circRNA, circ_0004674 in triple-negative breast cancer (TNBC), and the related downstream mechanism.

METHODS

The expression of circ_0004674 in TNBC tissues and cells was determined followed by analysis of the correlation between circ_0004674 and TNBC patients' prognosis. The interaction between circ_0004674, miR-377-3p, E2F6, and PNO1 was then identified using bioinformatics analysis combined with FISH, RIP, RNA pull-down, RT-qPCR, and Western blot analysis. Using gain-of-function and loss-of-function methods, we analyzed the effect of circ_0004674, miR-377-3p, E2F6, and PNO1 on TNBC in vivo and in vitro.

RESULTS

Increased circ_0004674 and E2F6 but decreased miR-377-3p were observed in TNBC tissues and MDA-MB-231 TNBC cells, all of which findings were associated with poor prognosis in patients with TNBC. Silencing of circ_0004676 remarkably suppressed the proliferation, cell cycle progression, and migration of TNBC cells in vitro, as well as inhibiting tumorigenesis and metastasis in vivo. Additionally, circ_0004676 served as a sponge of miR-377-3p which bound to the transcription factor E2F6. In the presence of overexpression of circ_0004676, E2F6 expression and its target PNO1 expression were elevated, while miR-377-3p expression was decreased. Interestingly, overexpression of E2F6 could reverse the inhibitory effect on tumor growth caused by downregulation of circ_0004676.

CONCLUSION

Our study highlighted the carcinogenic effect of circ_0004676 on TNBC through regulation of the miR-377-3p/E2F6/PNO1 axis. 1. Circ_0004674 is highly expressed in TNBC tissues and cells. 2. Circ_0004674 upregulates the expression of E2F6 by sponging miR-377-3p. 3. E2F6 upregulates PNO1 by binding to the PNO1 promoter. 4. Circ_0004674 favors TNBC progression by regulating the miR-377-3p/E2F6/PNO1 axis. 5. This study provides a new target for the treatment of TNBC.

Exploiting Long Non-Coding RNAs and Circular RNAs as Pharmacological Targets in Triple-Negative Breast Cancer Treatment

Breast cancer is one of the most frequent causes of cancer death among women worldwide. In particular, triple-negative breast cancer (TNBC) represents the most aggressive breast cancer subtype because it is characterized by the absence of molecular targets, thus making it an orphan type of malignancy. The discovery of new molecular druggable targets is mandatory to improve treatment success. In that context, non-coding RNAs represent an opportunity for modulation of cancer. They are RNA molecules with apparently no protein coding potential, which have been already demonstrated to play pivotal roles within cells, being involved in different processes, such as proliferation, cell cycle regulation, apoptosis, migration, and diseases, including cancer. Accordingly, they could be used as targets for future TNBC personalized therapy. Moreover, the peculiar characteristics of non-coding RNAs make them reliable biomarkers to monitor cancer treatment, thus, to monitor recurrence or chemoresistance, which are the most challenging aspects in TNBC. In the present review, we focused on the oncogenic or oncosuppressor role of long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs) mostly involved in TNBC, highlighting their mode of action and depicting their potential role as a biomarker and/or as targets of new non-coding RNA-based therapeutics.

A lncRNA-disease association prediction model based on the two-step PU learning and fully connected neural networks

Long non-coding RNAs (lncRNAs) have been shown to play a regulatory role in various processes of human diseases. However, lncRNA experiments are inefficient, time-consuming and highly subjective, so that the number of experimentally verified associations between lncRNA and diseases is limited. In the era of big data, numerous machine learning methods have been proposed to predict the potential association between lncRNA and diseases, but the characteristics of the associated data were seldom explored. In these methods, negative samples are randomly selected for model training and the model is prone to learn the potential positive association error, thus affecting the prediction accuracy. In this paper, we proposed a cyclic optimization model of predicting lncRNA-disease associations (COPTLDA in short). In COPTLDA, the two-step training strategy is adopted to search for the samples with the greater probability of being negative examples from unlabeled samples and the determined samples are treated as negative samples, which are combined together with known positive samples to train the model. The searching and training steps are repeated until the best model is obtained as the final prediction model. In order to evaluate the performance of the model, 30% of the known positive samples are used to calculate the model accuracy and 10% of positive samples are used to calculate the recall rate of the model. The sampling strategy used in this paper can improve the accuracy and the AUC value reaches 0.9348. The results of case studies showed that the model could predict the potential associations between lncRNA and malignant tumors such as colorectal cancer, gastric cancer, and breast cancer. The predicted top 20 associated lncRNAs included 10 colorectal cancer lncRNAs, 2 gastric cancer lncRNAs, and 8 breast cancer lncRNAs.

MicroRNA-377: A therapeutic and diagnostic tumor marker

Cancer is considered as one of the main causes of human deaths globally. Despite the recent progresses in therapeutic modalities, there is still a high rate of mortality among cancer patients. Late diagnosis in advanced tumor stages is one of the main reasons for treatment failure in cancer patients. Therefore, it is required to suggest the novel strategies for the early tumor detection. MicroRNAs (miRNAs) have critical roles in neoplastic transformation by regulation of cell proliferation, migration, and apoptosis. They are always considered as non-invasive markers due to their high stability in body fluids. Since, all of the miRNAs have tissue-specific functions in different tumors as tumor suppressor or oncogene; it is required to investigate the molecular mechanisms of every miRNA in different tumors to introduce that as a suitable non-invasive diagnostic marker in cancer patients. For the first time in the present review, we discussed the role of miR-377 during tumor progression. It has been reported that miR-377 mainly functions as a tumor suppressor through the regulation of signaling pathways and transcription factors. This review is an important step toward introducing the miR-377 as a novel diagnostic marker as well as a therapeutic target in cancer patients.

Coding roles of long non-coding RNAs in breast cancer: Emerging molecular diagnostic biomarkers and potential therapeutic targets with special reference to chemotherapy resistance

Dysregulation of epigenetic mechanisms have been depicted in several pathological consequence such as cancer. Different modes of epigenetic regulation (DNA methylation (hypomethylation or hypermethylation of promotor), histone modifications, abnormal expression of microRNAs (miRNAs), long non-coding RNAs, and small nucleolar RNAs), are discovered. Particularly, lncRNAs are known to exert pivot roles in different types of cancer including breast cancer. LncRNAs with oncogenic and tumour suppressive potential are reported. Differentially expressed lncRNAs contribute a remarkable role in the development of primary and acquired resistance for radiotherapy, endocrine therapy, immunotherapy, and targeted therapy. A wide range of molecular subtype specific lncRNAs have been assessed in breast cancer research. A number of studies have also shown that lncRNAs may be clinically used as non-invasive diagnostic biomarkers for early detection of breast cancer. Such molecular biomarkers have also been found in cancer stem cells of breast tumours. The objectives of the present review are to summarize the important roles of oncogenic and tumour suppressive lncRNAs for the early diagnosis of breast cancer, metastatic potential, and chemotherapy resistance across the molecular subtypes.

LOC554202 contributes to chordoma progression by sponging miR-377-3p and up-regulating SMAD3

Chordoma is a rare malignant bone tumor originating from the remnants of the notochord. Here, the role of long noncoding LOC554202 in chordoma progression and its associated mechanism were explored. Cell proliferation was analyzed by 3-(4, 5-dimethylthiazol-2-yl)-2, 5 diphenyltetrazolium bromide and colony formation assays. Flow cytometry was conducted to analyze cell apoptosis rate. The migration and invasion of chordoma cells were analyzed by transwell migration and invasion assays and wound healing assays. A xenograft tumor model was established in nude mice to explore the role of LOC554202 in regulating tumor growth in vivo . The interaction between microRNA-377-3p (miR-377-3p) and LOC554202 or sekelsky mothers against d PP (SMAD) family member 3 (SMAD3) was verified by dual-luciferase reporter and RNA immunoprecipitation assays. The glycolytic rate of chordoma cells was analyzed using glucose assay kit, lactic acid kit and ApoSENSOR ADP/ATP ratio assay kit. LOC554202 expression was upregulated in chordoma tissues and cell lines. LOC554202 silencing suppressed the proliferation, migration and invasion and induced the apoptosis of chordoma cells. LOC554202 knockdown restrained xenograft tumor growth in vivo . miR-377-3p was confirmed as a target of LOC554202, and miR-377-3p silencing largely overturned LOC554202 knockdown-mediated anti-tumor effects in chordoma cells. miR-377-3p interacted with the 3' untranslated region (3'UTR) of SMAD3 and miR-377-3p overexpression-mediated antitumor effects in chordoma cells were largely attenuated by SMAD3 overexpression. LOC554202 could positively regulate SMAD3 expression by sponging miR-377-3p in chordoma cells. LOC554202 contributed to the glycolysis of chordoma cells by targeting binding to miR-377-3p/SMAD3 axis. LOC554202 facilitated the proliferation, migration, invasion and glycolysis and inhibited the apoptosis of chordoma cells by mediating miR-377-3p/SMAD3 axis.

Identification of miRNAs and related hub genes associated with the triple negative breast cancer using integrated bioinformatics analysis and in vitro approach

Triple negative breast cancer (TNBC) is an aggressive breast cancer subtype generally associated with younger women. Due to the lack of suitable drugable targets in TNBC, the microRNAs are considered as a better hope as therapeutic agents for the management of the disease. In this study, we identified differentially expressed miRNAs (DEMs) and associated hub genes in TNBC microarray data (GSE38167, GSE60714, and GSE10833) using bioinformatics tools. The identified miRNAs and genes were validated in the TNBC cell line model (MDA-MB-231) compared with the normal breast cells (MCF-10A) using the qRT-PCR technique. False-positive DEMs were avoided by comparing the DEMs profile of TNBC and triple positive breast cancer (TPBC) cell line model (BT474) compared with the MCF-10A cells data. In addition, we studied the effect of anticancer phytochemicals on the differential expression of miRNAs and genes in MDA-MB-231 cells. Furthermore, target predictions, functional enrichment and KEGG pathway analysis, mutation and copy number alterations, and overall survival analysis of DEMs in TNBC sample was investigated using standard computational tools. The study identifies first time the association of hsa-miR-1250, has-miR-1273, and has-miR-635 with the TNBC. DEMs showed significant association with the Wnt, ErbB, PI3-Akt and cAMP signaling pathways having clinical implications in TNBC tumorigenesis. The DEMs and hub genes (HOXC6 and ACVR2B) showed survival disadvantages in TNBC patients. In summary, the identified miRNAs and hub genes show important implications in TNBC tumorigenesis and patient survival. We recommend further experimental studies on pathophysiological mechanism of the identified miRNAs and hub genes in TNBC.Communicated by Ramaswamy H. Sarma.

ceRNA network of lncRNA MIR210HG/miR-377-3p/LMX1A in malignant proliferation of glioma cells

BACKGROUND

Glioma represents the most heterogeneous and malignant form of brain tumor with a poor prognosis. The long non-coding RNA (LncRNA)-mediated competing endogenous RNA (ceRNA) network plays a regulatory role in cancer progression.

OBJECTIVES

The present study was conducted to expound on the role of lncRNA MIR210 host gene (MIR210HG)-mediated ceRNA mechanism in the malignant proliferation of glioma cells and provide a novel theoretical basis for the treatment of glioma.

METHODS

Expression levels of lncRNA MIR210HG, microRNA (miR)-377-3p, and LIM homeobox transcription factor 1 alpha (LMX1A) in glioma tissues and cells were determined by reverse-transcription quantitative polymerase chain reaction. Then, cell proliferation was assessed by cell counting kit-8 and colony formation assays. After that, the subcellular localization of lncRNA MIR210HG was analyzed by subcellular fractionation assay and the bindings of miR-377-3p to lncRNA MIR210HG and LMX1A were analyzed by the dual-luciferase assay. Glioma cells were transfected with si-MIR210HG, miR-377-3p inhibitor, or overexpressed-LMX1A vectors to evaluate their effects on the malignant proliferation of glioma cells.

RESULTS

LncRNA MIR210HG was elevated in glioma tissues and cells and inhibition of lncRNA MIR210HG reduced the proliferation potential of glioma cells. LncRNA MIR210HG targeted and inhibited miR-377-3p and miR-377-3p targeted and inhibited LMX1A transcription. miR-377-3p downregulation or LMX1A overexpression reversed the inhibition of silencing lncRNA MIR210HG on glioma cell proliferation.

CONCLUSION

LncRNA MIR210HG was upregulated in glioma tissues and cells and inhibition of lncRNA MIR210HG suppressed glioma cell proliferation through promoting miR-377-3p and repressing LMX1A.

The Role of Hypoxia-Associated Long Non-Coding RNAs in Breast Cancer

Breast cancer is the leading cause of cancer-related deaths in women worldwide. In the United States, even with earlier diagnosis and treatment improvements, the decline in mortality has stagnated in recent years. More research is needed to provide better diagnostic, prognostic, and therapeutic tools for these patients. Long non-coding RNAs are newly described molecules that have extensive roles in breast cancer. Emerging reports have shown that there is a strong link between these RNAs and the hypoxic response of breast cancer cells, which may be an important factor for enhanced tumoral progression. In this review, we summarize the role of hypoxia-associated lncRNAs in the classic cancer hallmarks, describing their effects on the upstream and downstream hypoxia signaling pathway and the use of them as diagnostic and prognostic tools.

A Novel Necroptosis-Associated lncRNA Signature Can Impact the Immune Status and Predict the Outcome of Breast Cancer

Breast cancer (BRCA) is one of the leading causes of death among women worldwide, and drug resistance often leads to a poor prognosis. Necroptosis is a type of programmed cell death (PCD) and exhibits regulatory effects on tumor progression, but few studies have focused on the relationships between necroptosis-associated lncRNAs and BRCA. In this study, we established a signature basis of 7 necroptosis-related lncRNAs associated with prognosis and divided BRCA patients into high- and low-risk groups. Kaplan-Meier curves all showed an adverse prognosis for patients in the high-risk group. Cox assays confirmed that risk score was an independent prognostic factor for BRCA patients. The receiver operating characteristic (ROC) curve proved the predictive accuracy of the signature and the area under the curve (AUC) values of the risk score reached 0.722. The nomogram relatively accurately predicted the prognosis of the patients. GSEA analysis suggested that the related signaling pathways and biological processes enriched in the high- and low-risk groups may influence the tumor microenvironment (TME) of BRCA. ssGSEA showed the difference in immune cell infiltration, immune pathway activation, and immune checkpoint expression between the two risk groups, with the low-risk group more suitable for immunotherapy. According to the significant difference in IC50 between risk groups, patients can be guided for an individualized treatment plan. Overall, the authors established a prognostic signature consisting of 7 necroptosis-associated lncRNAs that can independently predict the clinical outcome of BRCA patients. The difference in the tumor immune microenvironment between the low- and high-risk populations may be the reason for the resistance to immunotherapy in some patients.

LINC00339: An emerging major player in cancer and metabolic diseases

Long noncoding RNAs (lncRNAs) are a series of RNA molecules without ability to code proteins. LncRNAs have emerged as significant players in almost all aspects of gene function and regulation and play crucial roles in many human diseases. Particular lncRNAs are deemed to be promising molecular biomarkers used for diagnosing diseases and determining patient prognoses and treatment efficacies. LINC00339 is a new budding lncRNA and much of evidence shows that it is abnormally expressed in multifarious diseases, including endometriosis, cardiomyocyte apoptosis, osteoporosis, digestive-system tumors, respiratory-system tumors, nervous-system tumors, and diseases involving other systems. Additionally, LINC00339 is remarkably associated with different clinical features, such as tumor size, TNM stage, and pathological grade. LINC00339 expression has been proved to upregulate in the aforementioned diseases and has been identified to promote disease occurrence and development. It is also reported that LINC00339 is associated with various cellular events, such as tumor cell proliferation, motility and invasiveness, the expression has also been proved that it is closely related to clinical symptoms in cancer patients. This review summarizes the relationships among expression levels, biological features, clinical symptoms, and regulatory mechanisms of LINC00339 in several diseases and discusses the clinical applications of LINC00339 as a cancer diagnostic, prognostic and treatment efficacy biomarker.

lncRNA GHET1 Promotes the Progression of Triple-Negative Breast Cancer via Regulation of miR-377-3p/GRSF1 Signaling Axis

Objective

This study is aimed at investigating the role of lncRNA GHET1 in the progression of triple-negative breast cancer (TNBC).

Methods

Tumor tissues and paracancerous tissues (normal) of TNBC patients were collected. Human normal breast cells (MCF10A) and TNBC cells (MDA-MB-468 and HCC1937) were employed for in vitro analysis. The expression of lncRNA GHET1, miR-377-3p, and GRSF1 was detected by qRT-PCR. The lncRNA GHET1 and miR-377-3p were overexpressed or knocked down in the TNBC cells, respectively. To determine the specific biological activities of the TNBC cells, MTT, flow cytometry, and wound healing assay were adopted to evaluate the cellular proliferation, apoptosis, and migration abilities, respectively. MMP-9 and MMP-2 protein expression levels were detected as well by Western blot in the cells. The relationship between miR-377-3p and lncRNA GHET1, miR-377-3p, and GRSF1 was validated using dual-luciferase reporter assay.

Results

lncRNA GHET1 was significantly upregulated in the TNBC patients' tissues and the TNBC cell lines. Overexpression of lncRNA GHET1 significantly increased the proliferation and migration ability, but decreased apoptosis in the TNBC cells. Additionally, overexpression of lncRNA GHET1 upregulated both MMP-9 and MMP-2 protein expression levels. Correlation analysis found that miR-377-3p had a positive relationship with GRSF1, but had a negative relationship with lncRNA GHET1. miR-377-3p mimic attenuated the effects of lncRNA GHET1 on cellular proliferation, apoptosis, and migration of the TNBC cells.

Conclusion

lncRNA GHET1 promotes TNBC progression through the miR-377-3p/GRSF1 signaling axis.

circ-CFH promotes the development of HCC by regulating cell proliferation, apoptosis, migration, invasion, and glycolysis through the miR-377-3p/RNF38 axis

Circular RNAs (circRNAs) have previously been confirmed to function as vital regulators in multiple human cancers, including hepatocellular carcinoma (HCC). This study aimed to clarify the role and underlying molecular mechanisms of circ-CFH in HCC. circ-CFH was overexpressed in HCC tissues and cells, and the downregulation of circ-CFH inhibited the development of HCC by repressing cell proliferation, migration, invasion, and glycolysis while enhancing apoptosis in vitro, as well as inhibited tumor growth in vivo. miR-377-3p was negatively regulated by circ-CFH, and silencing of miR-377-3p abolished circ-CFH knockdown-mediated effects on HCC cells. Moreover, overexpression of miR-377-3p could impede the HCC process by targeting RNF38. Mechanistically, the circ-CFH/miR-377-3p/RNF38 axis regulated the progression of HCC cells, which might provide new diagnostic markers for HCC.

The functional significance and cross-talk of non-coding RNAs in triple negative and quadruple negative breast cancer

One of the leading causes of cancer-related deaths worldwide is breast cancer, among which triple-negative breast cancer (TNBC) is the most malignant and lethal subtype. This cancer accounts for 10-20% of all breast cancer deaths. Proliferation, tumorigenesis, and prognosis of TNBC are affected when the androgen receptor (AR) is not expressed, and it is classified as quadruple negative breast cancer (QNBC). Non-coding RNAs, such as microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs), play a significant role in tumorigenesis by virtue of their oncogenic and tumor-suppressive properties. To regulate tumorigenesis, miRNAs interact with their target mRNAs and modulate their expression, whereas lncRNAs can either act alone or interact with miRNAs or other molecules through various signaling pathways. Conversely, circRNAs regulate tumorigenesis by acting as miRNA sponges predominantly. Recently, non-coding RNAs were studied comprehensively for their roles in tumor proliferation, progression, and metastasis. As a result of existing studies and research progress, non-coding RNAs have been implicated in TNBC, necessitating their use as biomarkers for future diagnostic applications. In this review, the non-coding RNAs are explicitly implicated in the regulation of breast cancer, and their cross-talk between TNBC and QNBC is also discussed.

Development and validation of a circulating microRNA panel for the early detection of breast cancer

BACKGROUND

Mammography is widely used for breast cancer screening but suffers from a high false-positive rate. Here, we perform the largest comprehensive, multi-center study to date involving diverse ethnic groups, for the identification of circulating miRNAs for breast cancer screening.

METHODS

This study had a discovery phase (n = 289) and two validation phases (n = 374 and n = 379). Quantitative PCR profiling of 324 miRNAs was performed on serum samples from breast cancer (all stages) and healthy subjects to identify miRNA biomarkers. Two-fold cross-validation was used for building and optimising breast cancer-associated miRNA panels. An optimal panel was validated in cohorts with Caucasian and Asian samples. Diagnostic ability was evaluated using area under the curve (AUC) analysis.

RESULTS

The study identified and validated 30 miRNAs dysregulated in breast cancer. An optimised eight-miRNA panel showed consistent performance in all cohorts and was successfully validated with AUC, accuracy, sensitivity, and specificity of 0.915, 82.3%, 72.2% and 91.5%, respectively. The prediction model detected breast cancer in both Caucasian and Asian populations with AUCs ranging from 0.880 to 0.973, including pre-malignant lesions (stage 0; AUC of 0.831) and early-stage (stages I-II) cancers (AUC of 0.916).

CONCLUSIONS

Our panel can potentially be used for breast cancer screening, in conjunction with mammography.

Role of MicroRNAs and Long Non-Coding RNAs in Regulating Angiogenesis in Human Breast Cancer- A Molecular Medicine Perspective

MicroRNAs (miRNAs) and long non-coding RNAs (lncRNAs) are proficient in regulating gene expression post-transcriptionally. Considering the recent trend in exploiting non-coding RNAs (ncRNAs) as cancer therapeutics, the potential use of miRNAs and lncRNAs as biomarkers and novel therapeutic agents against angiogenesis is an important scientific aspect. An estimated 70% of the genome is actively transcribed, only 2% of which codes for known protein-coding genes. Long noncoding RNAs (lncRNAs) are a large and diverse class of RNAs > 200 nucleotides in length, and not translated into protein, and are of utmost importance and it governs the expression of genes in a temporal, spatial, and cell context-dependent manner. Angiogenesis is an essential process for organ morphogenesis and growth during development, and it is relevant during the repair of wounded tissue in adults. It is coordinated by an equilibrium of pro-and anti-angiogenic factors; nevertheless, when affected, it promotes several diseases, including breast cancer. Signaling pathways involved here are tightly controlled systems that regulate the appropriate timing of gene expression required for the differentiation of cells down a particular lineage essential for proper tissue development. Lately, scientific reports are indicating that ncRNAs, such as miRNAs, and lncRNAs, play critical roles in angiogenesis related to breast cancer. The specific roles of various miRNAs and lncRNAs in regulating angiogenesis in breast cancer, with particular focus on the downstream targets and signaling pathways regulated by these ncRNAs with molecular medicine perspective, are highlighted in this write-up.

Serum exosomal miR-377-3p and miR-381-3p as diagnostic biomarkers in colorectal cancer

Aim: This study aimed to identify specific and sensitive exosomal miRNAs in diagnosing patients with colorectal cancer (CRC). Methods: Serum exosomes were isolated from 175 CRC patients and 172 healthy donors by ultracentrifugation and identified by transmission electron microscopy, nanoparticle tracking analysis and western blotting. Exosomal miRNA expression was detected by qPCR and the results analyzed by receiver operating characteristic analysis to illuminate the diagnostic accuracy. Results: Both exosomal miR-377-3p and miR-381-3p were downregulated in CRC patients as well as in early-stage patients compared with healthy donors; they could serve as circulating biomarkers of diagnosis, including early diagnosis, for CRC, possessing favorable diagnostic efficiency. Conclusion: Exosomal miR-377-3p and miR-381-3p levels were downregulated in CRC patients and may be useful as novel and specific biomarkers for the diagnosis of CRC, especially early-stage CRC.

Circular RNA circ-ERBB2 promotes HER2-positive breast cancer progression and metastasis via sponging miR-136-5p and miR-198

Background

Circular RNAs (circRNAs) are pivotal regulators of various human cancers and circ-ERBB2 is abnormally expressed in breast cancer cells. However, the role and mechanism of circ-ERBB2 in HER2-positive breast cancer are still unknown.

Methods

The circ-ERBB2 expressions in the tumor tissues of HER2-positive breast cancer patients were tested using quantitative real-time PCR. The circ-ERBB2 function was investigated by cell counting kit 8 assay, Transwell, flow cytometry and Western blot. Mechanistically, fluorescence in situ hybridization, RNA immunoprecipitation, RNA pull-down and dual-luciferase reporter gene assays were conducted to confirm the interaction between circ-ERBB2 and miR-136-5p or miR-198 in HER2-positive breast cancer cells.

Results

Circ-ERBB2 was elevated in the tumor tissues of HER2-positive breast cancer patients. Functionally, the interference with circ-ERBB2 repressed HER2-positive breast cancer cell proliferation, migration, invasion and accelerated cell apoptosis. Furthermore, the mechanistic analysis corroborated that circ-ERBB2 acted as a competing endogenous RNA for miR-136-5p or miR-198 to relieve the repressive influence of miR-136-5p or miR-198 on its target transcription factor activator protein 2C (TFAP2C). Meanwhile, in vivo assays further corroborated the oncogenic function of circ-ERBB2 in HER2-positive breast cancer.

Conclusions

Circ-ERBB2 accelerated HER2-positive breast cancer progression through the circ-ERBB2/miR-136-5p/TFAP2C axis or the circ-ERBB2/miR-198/TFAP2C axis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-021-03114-8.

lncRNA and breast cancer: Progress from identifying mechanisms to challenges and opportunities of clinical treatment

Breast cancer is a malignant tumor that has a high mortality rate and mostly occurs in women. Although significant progress has been made in the implementation of personalized treatment strategies for molecular subtypes in breast cancer, the therapeutic response is often not satisfactory. Studies have reported that long non-coding RNAs (lncRNAs) are abnormally expressed in breast cancer and closely related to the occurrence and development of breast cancer. In addition, the high tissue and cell-type specificity makes lncRNAs particularly attractive as diagnostic biomarkers, prognostic factors, and specific therapeutic targets. Therefore, an in-depth understanding of the regulatory mechanisms of lncRNAs in breast cancer is essential for developing new treatment strategies. In this review, we systematically elucidate the general characteristics, potential mechanisms, and targeted therapy of lncRNAs and discuss the emerging functions of lncRNAs in breast cancer. Additionally, we also highlight the advantages and challenges of using lncRNAs as biomarkers for diagnosis or therapeutic targets for drug resistance in breast cancer and present future perspectives in clinical practice.

Multifaceted roles of long non-coding RNAs in triple-negative breast cancer: biology and clinical applications

Triple-negative breast cancer (TNBC) is a heterogeneous breast cancer subtype that lacks targeted therapy due to the absence of estrogen, progesterone, and HER2 receptors. Moreover, TNBC was shown to have a poor prognosis, since it involves aggressive phenotypes that confer significant hindrance to therapeutic treatments. Recent state-of-the-art sequencing technologies have shed light on several long non-coding RNAs (lncRNAs), previously thought to have no biological function and were considered as genomic junk. LncRNAs are involved in various physiological as well as pathological conditions, and play a key role in drug resistance, gene expression, and epigenetic regulation. This review mainly focuses on exploring the multifunctional roles of candidate lncRNAs, and their strong association with TNBC development. We also summarise various emerging research findings that establish novel paradigms of lncRNAs function as oncogenes and/or tumor suppressors in TNBC development, suggesting their role as prospective therapeutic targets.

Roles of miRNA and lncRNA in triple-negative breast cancer

Triple-negative breast cancer (TNBC) is currently the most malignant subtype of breast cancer without effective targeted therapies, which makes its pathogenesis an important target for research. A growing number of studies have shown that non-coding RNA (ncRNA), including microRNA (miRNA) and long non-coding RNA (lncRNA), plays a significant role in tumorigenesis. This review summarizes the roles of miRNA and lncRNA in the progression, diagnosis, and neoadjuvant chemotherapy of TNBC. Aberrantly expressed miRNA and lncRNA are listed according to their roles. Further, it describes the multiple mechanisms that lncRNA shows for regulating gene expression in the nucleus and cytoplasm, and more importantly, describes lncRNA-regulated TNBC progression through complete combining with miRNA at the post-transcriptional level. Focusing on miRNA and lncRNA associated with TNBC can provide new insights for early diagnosis and treatment-they can be targeted in the future as a novel anticancer target of TNBC.

lncRNA LOXL1-AS1 promotes liver cancer cell proliferation and migration by regulating the miR-377-3p/NFIB axis

Liver cancer is becoming one of the most lethal malignancies due to its high incidence and mortality. Accumulating studies have indicated that long non-coding RNAs (lncRNAs) are critical regulators of the tumorigenesis and development of various types of cancer, including liver cancer. LncRNA LOXL1-antisense RNA 1 (LOXL1-AS1) has been identified as an oncogene in some types of human cancer; however, its role in liver cancer remains obscure. Reverse transcription-quantitative PCR was used to measure LOXL1-AS1 expression in liver cancer tissues and cells. Western blot, MTT, colony formation, glucose uptake and wound healing assays were used to explore the biological function of LOXL1-AS1 in liver cancer cells. Bioinformatics analysis and RNA pull-down and luciferase reporter assays were used to explore the molecular mechanism of LOXL1-AS1 in liver cancer cells. Statistical analysis was used to compare the experimental results of different groups. In the present study, LOXL1-AS1 expression was significantly upregulated in liver cancer tissues and cells compared with in normal liver tissues and cells, respectively. High LOXL1-AS1 expression was associated with poor clinical outcomes in patients with liver cancer. Furthermore, LOXL1-AS1-knockdown suppressed glucose metabolism, proliferation, migration and epithelial-mesenchymal transition (EMT) of liver cancer cells. Subsequently, LOXL1-AS1 acted as a microRNA (miR)-377-3p sponge, and nuclear factor I B (NFIB) was confirmed as the downstream target of miR-377-3p in liver cancer cells. Additionally, rescue assays suggested that NFIB overexpression countervailed the inhibitory influence of LOXL1-AS1 silencing on liver cancer cellular processes. The present study demonstrated that LOXL1-AS1 promoted glucose metabolism, proliferation, migration and EMT of liver cancer cells by sponging miR-377-3p and modulating NFIB, which may provide a novel insight for the treatment of liver cancer.

Long noncoding RNAs in triple-negative breast cancer: A new frontier in the regulation of tumorigenesis

In recent years, triple-negative breast cancer (TNBC) has emerged as the most aggressive subtype of breast cancer and is usually associated with increased mortality worldwide. The severity of TNBC is primarily observed in younger women, with cases ranging from approximately 12%-24% of all breast cancer cases. The existing hormonal therapies offer limited clinical solutions in completely circumventing the TNBC, with chemoresistance and tumor recurrences being the common hurdles in the path of TNBC treatment. Accumulating evidence has correlated the dysregulation of long noncoding RNAs (lncRNAs) with increased cell proliferation, invasion, migration, tumor growth, chemoresistance, and decreased apoptosis in TNBC. Various clinical studies have revealed that aberrant expression of lncRNAs in TNBC tissues is associated with poor prognosis, lower overall survival, and disease-free survival. Due to these specific characteristics, lncRNAs have emerged as novel diagnostic and prognostic biomarkers for TNBC treatment. However, the underlying mechanism through which lncRNAs perform their actions remains unclear, and extensive research is being carried out to reveal it. Therefore, understanding of mechanisms regulating the modulation of lncRNAs will be a substantial breakthrough in effective treatment therapies for TNBC. This review highlights the association of several lncRNAs in TNBC progression and treatment, along with their possible functions and mechanisms.

HOXD Antisense Growth-Associated Long Noncoding RNA Promotes Triple-Negative Breast Cancer Progression by Activating Wnt Signaling Pathway

PURPOSE

Triple-negative breast cancer (TNBC) is the most lethal subtype of breast cancer owing to high heterogeneity, aggressive nature, and lack of treatment options, which has a substantial deleterious effect on patients' lives. HOXD antisense growth-associated long noncoding RNA (lncRNA) (HAGLR) plays tumor-promoting roles in many cancers. In this study, we aimed to explore the role of HAGLR in TNBC.

METHODS

Quantitative real-time polymerase chain reaction assays were used to examine the expression of RNAs. Functional experiments were conducted to test the biological behavior of TNBC cells. Moreover, MS2-RNA immunoprecipitation, luciferase reporter, and RNA pull-down assays were conducted to verify the binding relationship between HAGLR, microRNA-143-5p (miR-143-5p), and serine- and arginine-rich splicing factor 1 (SRSF1).

RESULTS

HAGLR was found to be highly expressed in TNBC tissues and cells, and inhibiting HAGLR suppressed cell proliferation, migration, and invasion and promoted cell apoptosis in TNBC. Meanwhile, miR-93-5p was shown to bind to HAGLR and SRSF1. In addition, SRSF1 plays an oncogenic role in TNBC. Importantly, HAGLR could activate the Wnt signaling pathway by sponging miR-93-5p to upregulate SRSF1; thus, accelerating TNBC progression.

CONCLUSION

HAGLR could promote the progression of TNBC through the miR-93-5p/SRSF1 axis to activate the Wnt signaling pathway.

HomeoboxC6 affects the apoptosis of human vascular endothelial cells and is involved in atherosclerosis

Apoptosis of vascular endothelial cells (VECs) is highly important in the occurrence and development of atherosclerosis (AS). HomeboxC6 (HOXC6) is expressed in higher levels in multiple malignant tissues, and it influences the malignant biological behavior of the cancer cells. However, the effects of HOXC6 on AS and the apoptosis of VECs have not been fully elucidated. In this study, we demonstrated that HOXC6 expression was increased in aortic wall of AS rats and peripheral blood monocytes of patients with coronary heart disease. Furthermore, it was uncovered that BAX expression was upregulated, while BCL-2 expression was downregulated in the aortic wall of AS rats. The apoptosis of human VECs (HVECs) cultured normally or treated with oxidized low-density lipoprotein in vitro was decreased after transfection with HOXC6-siRNA. Moreover, the results of Western blot analysis unveiled that the expressions of proapoptotic proteins, such as BAX, caspase-3, cleaved-caspase-3, and caspase-9 were reduced, while the expression of antiapoptotic protein, BCL-2, was elevated. Meanwhile, mRNA and protein expressions of phospholipase C beta (PLCβ) were decreased, the phosphorylation levels of protein kinase C zeta (PKCζ) and nuclear transcription factor-κB-p65 (NF-κBp65) and the membrane translocation of PKCζ were reduced as well. Besides, the expression of interleukin-18 (IL-18) protein was downregulated. However, after overexpression of HOXC6, the opposite trends of the abovementioned indices were observed. Furthermore, the inhibition of apoptosis induced by HOXC6-siRNA was reversed by lysophosphatidylcholine, an activator of PKCζ. Taken together, our results indicated that HOXC6 can promote the apoptosis of HVECs and may be involved in the occurrence and development of AS, which may be partially associated with the activation of PLCβ/PKCζ/NF-κBp65/IL-18 signaling pathway.

LncRNA PRNCR1 Promotes Breast Cancer Proliferation and Inhibits Apoptosis by Modulating microRNA-377/CCND2/MEK/MAPK Axis

BACKGROUND

Long non-coding RNAs (lncRNAs) have recently become the vital gene regulators in diverse cancers. In our study, we purposed to inquiry into the mechanisms of lncRNA PRNCR1 in breast cancer via microRNA-377 (miR-377)/CCND2/MEK/MAPK axis.

METHODS

PRNCR1 expression in breast cancer tissues was detected, and the correlation between PRNCR1 expression and prognostic survival was analyzed. The expressions of PRNCR1 and miR-377 in breast cancer cell lines were detected. Relationships among PRNCR1, miR-377 and CCND2 were confirmed by luciferase activity, RNA pull-down or RIP assays. Breast cancer cells were introduced with silenced PRNCR1 or restored miR-377 to explore their functions in malignant phenotype of breast cancer cells. The expression of MEK/MAPK pathway-related proteins was determined by western blot analysis.

RESULTS

PRNCR1 was highly expressed and miR-377 was poorly expressed in patients with breast cancer, and patients with high expression of PRNCR1 had a poor prognosis. PRNCR1 silencing or miR-377 overexpression resulted in suppressed breast cancer cell proliferation ability, blocked cell cycle process and induced apoptosis. PRNCR1 regulated CCND2 expression by competitively binding to miR-377. CCND2 activated the MEK/MAPK pathway, and after treatment with Mirdametinib, the MEK/MAPK pathway was inhibited, which was found to retard breast cancer growth.

CONCLUSION

Our study highlights that lncRNA PRNCR1 may competitively bind to miR-377, leading to upregulated CCND2, which in turn activated MEK/MAPK pathway to promote breast cancer growth.

Elucidating the role of long intergenic non-coding RNA 339 in human endometrium and endometriosis

Endometriosis is a complex disease, influenced by genetic factors. Genetic markers associated with endometriosis exist at chromosome 1p36.12 and lead to altered expression of the long intergenic non-coding RNA 339 (LINC00339), however, the role of LINC00339 in endometriosis pathophysiology remains unknown. The aim of this work was to characterize the expression patterns of LINC00339 mRNA in endometrium and endometriotic lesions in situ and to determine the functional role of LINC00339 in human endometrium. We employed RNA-sequencing (RNA-seq), quantitative RT-PCR and in situ hybridization to investigate the abundance of LINC00339 transcripts in endometrium and endometrial cell lines and to describe the pattern and localization of LINC00339 expression in endometrium and endometriotic lesions. LINC00339 mRNA expression was manipulated (overexpressed and silenced) in endometrial stromal cell lines and RNA-seq data from overexpression models were analysed using online bioinformatics platforms (STRING and Ingenuity Pathway Analysis) to determine functional processes. We demonstrated the expression of LINC00339 in endometriotic lesions for the first time; we found LINC00339 expression was restricted to the lesion foci and absent in surrounding non-lesion tissue. Furthermore, manipulation of LINC00339 expression in endometrial stromal cell lines significantly impacted the expression of genes involved in immune defence pathways. These studies identify a novel mechanism for LINC00339 activity in endometrium and endometriosis, paving the way for future work, which is essential for understanding the pathogenesis of endometriosis.

The role of EMT-related lncRNA in the process of triple-negative breast cancer metastasis

Triple-negative breast cancer (TNBC) is the most malignant and fatal subtype of breast cancer, which has characterized by negativity expression of ER, PR, and HER2. Metastasis is the main factor affecting the prognosis of TNBC, and the process of metastasis is related to abnormal activation of epithelial–mesenchymal transition (EMT). Recent studies have shown that long non-coding RNA (LncRNA) plays an important role in regulating the metastasis and invasion of TNBC. Therefore, based on the metastasis-related EMT signaling pathway, great efforts have confirmed that LncRNA is involved in the molecular mechanism of TNBC metastasis, which will provide new strategies to improve the treatment and prognosis of TNBC. In this review, we summarized many signal pathways related to EMT involved in the transfer process. The advances from the most recent studies of lncRNAs in the EMT-related signal pathways of TNBC metastasis. We also discussed the clinical research, application, and challenges of LncRNA in TNBC.

The long non-coding RNA landscape in triple-negative breast cancer

Triple-negative breast cancer (TNBC) is a type of breast cancer that has a higher risk of distant recurrence and metastasis, leading to a relatively aggressive biological behaviour and poor outcome. So far, the clinical management of TNBC is challenging because of its heterogeneity and paucity of specific targeted therapy. Recently, various studies have identified a lot of differently expressed long non-coding RNAs (lncRNAs) in TNBC. Those lncRNAs have been reported to play important roles in the multistep process of TNBC tumorigenesis. Here, we review the biological characteristics of lncRNAs, and present the current state of knowledge concerning the expression, function and regulation of lncRNAs in TNBC. Accumulating studies explored the potential lncRNAs-based therapeutics in TNBC, including the techniques of genetic modification using antisense oligonucleotides, locked nucleic acid and RNA nanotechnology. In current review, we also discuss the future prospects of studies about lncRNAs in TNBC and development of lncRNA-based strategies for clinical TNBC patients.

A novel circular RNA hsa_circRNA_103809/miR-377-3p/GOT1 pathway regulates cisplatin-resistance in non-small cell lung cancer (NSCLC)

Background

Cisplatin is the first-line chemotherapeutic drug for non-small cell lung cancer (NSCLC), and emerging evidences suggests that targeting circular RNAs (circRNAs) is an effective strategy to increase cisplatin-sensitivity in NSCLC, but the detailed mechanisms are still not fully delineated.

Methods

Cell proliferation, viability and apoptosis were examined by using the cell counting kit-8 (CCK-8) assay, trypan blue staining assay and Annexin V-FITC/PI double staining assay, respectively. The expression levels of cancer associated genes were measured by using the Real-Time qPCR and Western Blot analysis at transcriptional and translated levels. Dual-luciferase reporter gene system assay was conducted to validated the targeting sites among hsa_circRNA_103809, miR-377-3p and 3′ untranslated region (3’UTR) of GOT1 mRNA. The expression status, including expression levels and localization, were determined by immunohistochemistry (IHC) assay in mice tumor tissues.

Results

Here we identified a novel hsa_circRNA_103809/miR-377-3p/GOT1 signaling cascade which contributes to cisplatin-resistance in NSCLC in vitro and in vivo. Mechanistically, parental cisplatin-sensitive NSCLC (CS-NSCLC) cells were subjected to continuous low-dose cisplatin treatment to generate cisplatin-resistant NSCLC (CR-NSCLC) cells, and we found that hsa_circRNA_103809 and GOT1 were upregulated, while miR-377-3p was downregulated in CR-NSCLC cells but not in CS-NSCLC cells. In addition, hsa_circRNA_103809 sponged miR-337-3p to upregulate GOT1 in CS-NSCLC cells, and knock-down of hsa_circRNA_103809 enhanced the inhibiting effects of cisplatin on cell proliferation and viability, and induced cell apoptosis in CR-NSCLC cells, which were reversed by downregulating miR-377-3p and overexpressing GOT1. Consistently, overexpression of hsa_circRNA_103809 increased cisplatin-resistance in CS-NSCLC cells by regulating the miR-377-3p/GOT1 axis. Finally, silencing of hsa_circRNA_103809 aggravated the inhibiting effects of cisplatin treatment on NSCLC cell growth in vivo.

Conclusions

Analysis of data suggested that targeting the hsa_circRNA_103809/miR-377-3p/GOT1 pathway increased susceptibility of CR-NSCLC cells to cisplatin, and this study provided novel targets to improve the therapeutic efficacy of cisplatin for NSCLC treatment in clinic.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-020-07680-w.

MiRNA and LncRNA as Potential Biomarkers in Triple-Negative Breast Cancer: A Review

Noncoding RNAs (ncRNAs) include a diverse range of RNA species, including microRNAs (miRNAs) and long noncoding RNAs (lncRNAs). MiRNAs, ncRNAs of approximately 19-25 nucleotides in length, are involved in gene expression regulation either via degradation or silencing of the messenger RNAs (mRNAs) and have roles in multiple biological processes, including cell proliferation, differentiation, migration, angiogenesis, and apoptosis. LncRNAs, which are longer than 200 nucleotides, comprise one of the largest and most heterogeneous RNA families. LncRNAs can activate or repress gene expression through various mechanisms, acting alone or in combination with miRNAs and other molecules as part of various pathways. Until recently, most research has focused on individual lncRNA and miRNA functions as regulators, and there is limited available data on ncRNA interactions relating to the tumor growth, metastasis, and therapy of cancer, acting either on mRNA alone or as competing endogenous RNA (ceRNA) networks. Triple-negative breast cancer (TNBC) represents approximately 10%-20% of all breast cancers (BCs) and is highly heterogenous and more aggressive than other types of BC, for which current targeted treatment options include hormonotherapy, PARP inhibitors, and immunotherapy; however, no targeted therapies for TNBC are available, partly because of a lack of predictive biomarkers. With advances in proteomics, new evidence has emerged demonstrating the implications of dysregulation of ncRNAs in TNBC etiology. Here, we review the roles of lncRNAs and miRNAs implicated in TNBC, including their interactions and regulatory networks. Our synthesis provides insight into the mechanisms involved in TNBC progression and has potential to aid the discovery of new diagnostic and therapeutic strategies.

The SP1-Induced Long Noncoding RNA, LINC00339, Promotes Tumorigenesis in Colorectal Cancer via the miR-378a-3p/MED19 Axis

Introduction

Accumulating evidence has indicated that long noncoding RNAs (lncRNAs) are pivotal regulators involved in the pathogenesis of cancer; however, the molecular mechanism of LINC00339 in colorectal cancer (CRC) remains unclear.

Methods

The quantitative real-time polymerase chain reaction for the expression of LINC00339 and miR-378a-3p and Western blots for MED19 were performed. A dual-luciferase assay was used to investigate the interaction between LIN00339 and miR-378a-3p, as well as between miR-378a-3p and MED19. Cell proliferation was determined by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) and 5-ethynyl-2ʹ-deoxyuridine (EdU) assay. The cell cycle was analyzed by propidium iodide staining followed by flow cytometry analysis. The wound-healing and transwell invasion assays were used to evaluate cell migration and invasion.

Results

The expression of LINC00339 was significantly upregulated in CRC cells and tissues, and high LINC00339 expression indicated an advanced tumor stage. Further experiments demonstrated that SP1 activated LINC00339 expression by binding to its promoter region. Luciferase activity and RNA pull-down assays demonstrated a direct interaction between LINC00339 and miR-378a-3p. miR-378a-3p expression was decreased in CRC samples and negatively correlated with LINC00339 expression in tumors. Gain- and loss-of-function assays indicated that LINC00339 contributed to cell proliferation, cell cycle progression, migration, and invasion, while miR-378a-3p reversed these effects. Furthermore, cotransfection of wild-type MED19 3ʹ-UTR reporters and miR-378a-3p significantly reduced luciferase activity. MED19 mRNA and protein expression was inhibited and enhanced by miR-378a-3p and LINC00339, respectively. MED19 overexpression reversed the effect of miR-378a-3p on cellular processes. Moreover, LINC00339 promoted tumor growth in vivo and induced epithelial–mesenchymal transition (EMT) and activated the Wnt/β-catenin signaling pathway in cells.

Conclusion

Our findings demonstrate the regulatory role of the SP1/LINC00339/miR-378a-3p/MED19 axis in CRC tumorigenesis and provide novel insight into the molecular mechanism underlying CRC.

Upregulated circPDK1 Promotes RCC Cell Migration and Invasion by Regulating the miR-377-3P-NOTCH1 Axis in Renal Cell Carcinoma

Background

Circular RNAs (circRNAs) are novel clusters of endogenous noncoding RNAs (ncRNAs) that are involved in the regulation of multiple biological processes in diverse types of cancers. However, the roles and precise mechanisms of circRNAs in renal cell carcinoma (RCC) occurrence and progression have not been clearly elucidated.

Methods

We identified the aberrantly expressed circRNAs in RCC by high-throughput RNA-seq assay and used qRT-PCR to test the expression level of circRNAs in RCC tissues. Loss-of-function experiments were executed to detect the biological roles of circPDK1 in the RCC cells both in vivo and in vitro. RNA Fish, luciferase reporter assays and Western blotting were used to explore the molecular mechanism of circPDK1 function. All data were expressed as the means ± standard error of the mean (SEM). Student’s t-test, one-way ANOVA, Cox regression, an LSD-t-test, Pearson’s chi-squared test, a Log-rank test, and linear regression analyses were used to evaluate the group differences. P < 0.05 was considered significant.

Results

CircPDK1 was overexpressed in RCC tissues and positively associated with patient tumor metastasis and renal cell invasion. The in vivo functional assays also revealed that circPDK1 drove RCC xenograft metastasis. CircPDK1 was mainly located in the cytoplasm, serving as a sponge of miR-377-3P to regulate RCC invasion and metastasis through NOTCH1 (Notch Homolog 1). Ectopic express of NOTCH1 in RCC cell lines will block the metastasis inhibition effect after circPDK1 knockdown.

Conclusion

CircPDK1 is aberrantly expressed in RCC and promotes the metastasis of RCC cells mainly through sponging miR-377-3P and reducing its negative regulation of NOTCH1. Thus, circPDK1 may act as a therapeutic target and biomarker for RCC.

CircZFR serves as a prognostic marker to promote bladder cancer progression by regulating miR-377/ZEB2 signaling

Circular RNAs (circRNAs) have been identified as crucial regulators of gene expression in human cancer biology. CircZFR is a novel identified circRNA and its effect in bladder cancer remains unclearly. In the present study, we aimed to investigate the role of circZFR in the progression of bladder cancer. First, we demonstrated that the expression of circZFR was higher in bladder cancer tissues and cells compared with adjacent non-tumor tissues and normal bladder epithelial cells. And higher circZFR levels were positively correlated with bladder cancer patients’ pathological T stage, grade, lymphatic metastasis, recurrence, progression-free survival (PFS) and overall survival (OS). Functionally, knockdown of circZFR could significantly prohibit cell growth, migration and invasion, arrest cell cycle as well as promote apoptosis of bladder cancer cells in vitro study. Mechanistically, we observed that circZFR could directly bind to miR-377 as sponge to promote ZEB2 expression in bladder cancer cells. In addition, rescue assays demonstrated that restoration of ZEB2 significantly impaired the suppressive effects of circZFR silencing on bladder cancer cells growth, migration and invasion. Taken together, our results illuminated that circZFR could be a prognostic biomarker in bladder cancer and exerted oncogenic roles through regulating miR-377/ZEB2 axis in bladder cancer, which indicated that circZFR could be a potential therapeutic target for bladder cancer patients treatment.

Circulating microRNAs and their role in the immune response in triple-negative breast cancer

Breast cancer (BC) is the most common type of cancer in women worldwide, and despite advances in treatments, its incidence and mortality are increasing. Therefore, it is necessary to develop new, non-invasive tests that provide more accurate diagnosis and prognosis in a timely manner. A promising approach is measuring the presence of biomarkers to detect tumors at various stages and determine their specific characteristics, thus allowing for more personalized treatment. MicroRNAs (miRNAs) serve a role in gene expression, primarily by interacting with messenger RNAs, and may be potential biomarkers for detecting cancer. They are detectable in tissues and blood, including plasma and/or serum, are stable and often tumor specific. Also, different miRNAs are associated with specific BC molecular subtypes. Triple-negative BC (TNBC) is a type of BC in which the primary targets for hormonal therapy are absent. It is an aggressive phenotype, which frequently metastasizes and is associated with an unfavorable prognosis. The present review focuses on circulating miRNAs in patients with TNBC, with an emphasis on their interaction with the immune response checkpoint genes PD-1, PD-L1 and CTLA4. Modulation and response of the immune system are of interest in cancer treatment due to the success of immunotherapy in the treatment of various neoplasms. Based on the findings of this literature review and the in silico analysis performed as part of this review, it is concluded that circulating hsa-miR-195 and hsa-miR-155 in TNBC interact with checkpoint genes involved in the immune response. Further analysis of the expression of these circulating miRNAs and their association with prognosis in patients with TNBC treated with immunotherapy should be assessed to evaluate their possible use as non-invasive predictive biomarkers. In addition, functional studies to analyze biologically relevant targets in the development and prognosis of TNBC, which could be therapeutic targets, are also recommended.

Abnormal expression of homeobox c6 in the atherosclerotic aorta and its effect on proliferation and migration of rat vascular smooth muscle cells

Homeobox c6 (Hoxc6) affects the proliferation, migration, and infiltration of malignant tumor cells; however, the effect of Hoxc6 on atherosclerosis (AS) as well as the proliferation and migration of vascular smooth muscle cells (VSMCs), which play a role in promoting AS, has not yet been well clarified. In the present study, we tested the hypothesis that Hoxc6 affects the proliferation and migration of rat VSMCs, and hence is involved in AS. The results showed that the expression of Hoxc6 mRNA and protein was higher in normal rat aortic wall than in the myocardium. Subsequently, a rat model of AS was established by high-fat feeding for 2 months. The expression of Hoxc6 mRNA and protein was increased significantly in AS lesions, while the expression of p53 protein was decreased and that of proliferating cell nuclear antigen (PCNA) was increased. Moreover, not only the proliferation and mobility of cells in normal culture were decreased, but also the proliferation was stimulated by oxidized low-density lipoprotein, which was decreased after downregulation of Hoxc6 expression in VSMCs in rat. Consecutively, the expression of PCNA protein was decreased, while that of p53 was increased. These results indicated that Hoxc6 is probably involved in AS via p53 and PCNA by affecting the proliferation and migration of VSMCs.

Long noncoding RNA LINC00339 promotes the oncogenicity of gastric cancer by regulating SRY-box 9 expression via sponging of microRNA-539

Differential expression of LINC00339 is involved in the malignancy of multiple human cancer types. Nonetheless, the expression profile, functions, and potential mechanisms of action of LINC00339 in gastric cancer are yet to be fully elucidated. This study aimed at measuring LINC00339 expression in gastric cancer and examining the prognostic significance of LINC00339 in patients with gastric cancer. The detailed functions of LINC00339 with regard to the aggressive characteristics of gastric cancer cells and the underlying molecular mechanisms were investigated. Here, we found that LINC00339 expression was aberrantly high in gastric cancer and significantly associated with lymph node metastasis, invasive depth, and TNM stage. Patients with gastric cancer in a LINC00339 high-expression group showed shorter overall survival than patients in a LINC00339 low-expression group. A knockdown of LINC00339 suppressed gastric cancer cell proliferation, migration, and invasion and induced apoptosis in vitro and slowed tumor growth in vivo. In terms of the mechanism, LINC00339 was found to act as a molecular sponge on microRNA-539 (miR-539). SRY-box 9 (SOX9) was confirmed as a direct target gene of miR-539 in gastric cancer cells. An miR-539 knockdown attenuated the effects of the LINC00339 knockdown on the malignant characteristics of gastric cancer cells. Overall, LINC00339 plays a critical role in the malignancy of gastric cancer by regulating SOX9 via sponging of miR‑539. Our findings highlight the importance of the LINC00339-miR-539-SOX9 pathway in gastric cancer pathogenesis and may point to novel targets for the diagnosis, prognosis, and/or treatment of gastric cancer.

Systematic characterization of non-coding RNAs in triple-negative breast cancer

Triple‐negative breast cancer (TNBC) is one of the most aggressive subtypes of breast cancer with negativity for oestrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor (HER2). Non‐coding RNAs (ncRNAs) make up most of the transcriptome and are widely present in eukaryotic cells. In recent years, emerging evidence suggests that ncRNAs, mainly microRNAs (miRNAs), long ncRNAs (lncRNAs) and circular RNAs (circRNAs), play prominent roles in the tumorigenesis and development of TNBC, but the functions of most ncRNAs have not been fully described. In this review, we systematically elucidate the general characteristics and biogenesis of miRNAs, lncRNAs and circRNAs, discuss the emerging functions of these ncRNAs in TNBC and present future perspectives in clinical practice.

Dysregulated lncRNA-miRNA-mRNA Network Reveals Patient Survival-Associated Modules and RNA Binding Proteins in Invasive Breast Carcinoma

Breast cancer is the most common cancer in women, but few biomarkers are effective in clinic. Previous studies have shown the important roles of non-coding RNAs in diagnosis, prognosis, and therapy selection for breast cancer and have suggested the significance of integrating molecules at different levels to interpret the mechanism of breast cancer. Here, we collected transcriptome data including long non-coding RNA (lncRNA), microRNA (miRNA), and mRNA for ~1,200 samples, including 1079 invasive breast carcinoma samples and 104 normal samples, from The Cancer Genome Atlas (TCGA) project. We identified differentially expressed lncRNAs, miRNAs, and mRNAs that distinguished invasive carcinoma samples from normal samples. We further constructed an integrated dysregulated network consisting of differentially expressed lncRNAs, miRNAs, and mRNAs and found housekeeping and cancer-related functions. Moreover, 58 RNA binding proteins (RBPs) involved in biological processes that are essential to maintain cell survival were found in the dysregulated network, and 10 were correlated with overall survival. In addition, we identified two modules that stratify patients into high- and low-risk subgroups. The expression patterns of these two modules were significantly different in invasive carcinoma versus normal samples, and some molecules were high-confidence biomarkers of breast cancer. Together, these data demonstrated an important clinical application for improving outcome prediction for invasive breast cancers.

ZEB1 induced-upregulation of long noncoding RNA ZEB1-AS1 facilitates the progression of triple negative breast cancer by binding with ELAVL1 to maintain the stability of ZEB1 mRNA

Triple-negative breast cancer (TNBC) is one of the malignant type of breast cancer. Previous study indicated that long noncoding RNA (lncRNA) ZEB1-AS1 was associated with the progression of several cancers. However, its underlying molecular mechanism in TNBC remains to be elucidated. In this study, ZEB1-AS1 expression was boosted in TNBC tissues and cell lines according to reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Inhibition of ZEB1-AS1 suppressed cell proliferation, migration, invasion, and promoted cell apoptosis in TNBC. Moreover, ZEB1-AS1 positively regulated ZEB1 expression. RT-qPCR disclosed ZEB1 expression was elevated in TNBC tissues and ZEB1 silence blocked TNBC progression. RNA pull-down and RNA immunoprecipitation assays revealed ZEB1-AS1 and ZEB1 both could bind with ELAVL1. ZEB1-AS1 maintained ZEB1 messenger RNA (mRNA) stability by binding with ELAVL1. In addition chromatin, immunoprecipitation and luciferase reporter assays confirmed that ZEB1 could bind with ZEB1-AS1 promoter and promoted ZEB1-AS1 expression. Rescue assays manifested ZEB1 overexpression could abolish the inhibitory effect caused by ZEB1-AS1 inhibition on TNBC progression. To sum up, ZEB1 induced-upregulation of ZEB1-AS1 maintained the stability of ZEB1 mRNA by binding with ELAVL1, which formed a feedback loop to facilitate TNBC progression. These findings might provide a new target for TNBC treatment.

hsa_circ_001653 Implicates in the Development of Pancreatic Ductal Adenocarcinoma by Regulating MicroRNA-377-Mediated HOXC6 Axis

Pancreatic ductal adenocarcinoma (PDAC) is an extremely aggressive pancreatic cancer with poor survival rate. Circular RNAs (circRNAs) signatures have been identified in some human cancers, but there are little data concerning their presence in PDAC. We investigated the role of hsa_circ_001653, a newly identified circRNA, in the development of PDAC. hsa-circ-001653 expression was measured in 83 paired normal and tumor tissues surgically resected from PDAC patients. Phenotypic changes of PDAC cells were evaluated by assays for cell viability, cell cycle, invasion, and apoptosis. Tube-like structure formation of human umbilical vein endothelial cells (HUVECs) was examined in the presence of PDAC cells. Cross-talk between hsa_circ_001653 and microRNA-377 (miR-377)/human homeobox C6 (HOXC6) was assessed using dual-luciferase reporter assay, Ago2 immunoprecipitation, and northern blot analysis. Nude mice were inoculated with human PDAC cells for in vivo analysis. hsa_circ_001653 was an upregulated circRNA in PDAC. Silencing of hsa_circ_001653 in PDAC cells via RNA interference inhibited cell viability, cell-cycle progression, in vitro angiogenesis, and invasive properties, showing a pro-apoptotic effect. hsa_circ_001653 was found to bind to miR-377, which in turn repressed HOXC6 expression. Inhibition of miR-377 by its specific inhibitor restored cell viability, cell-cycle progression, in vitro angiogenesis, and invasive properties in PDAC cells lacking endogenous hsa_circ_001653. When nude mice were inoculated with human PDAC cells, inhibition of hsa_circ_001653 had a therapeutic effect. Collectively, the present study provides an enhanced understanding of hsa_circ_001653 as a therapeutic target for PDAC.

Long Non-coding RNA LOXL1-AS1 Drives Breast Cancer Invasion and Metastasis by Antagonizing miR-708-5p Expression and Activity

LOXL1-AS1, a recently characterized long non-coding RNA (lncRNA), has been reported to modulate tumor progression in several types of cancer. However, the expression and role of LOXL1-AS1 in breast cancer remain unclear. In this study, we sought to identify novel lncRNA regulators engaged in breast cancer metastasis. To this end, we examined 42 cancer-related lncRNAs between MCF7 (with low metastatic potential) and MDA-MB-231 (with high metastatic potential) cells. These lncRNAs have been found to affect the invasiveness of several cancer types, but they are still undefined in breast cancer. Among the 42 candidates, LOXL1-AS1 is significantly increased in MDA-MB-231 cells relative to MCF7 cells. We also show that LOXL1-AS1 is upregulated in breast cancer tissues and cells compared to noncancerous counterparts. Increased LOXL1-AS1 expression is correlated with tumor stage and lymph node metastasis in breast cancer patients. Biologically, overexpression of LOXL1-AS1 enhances and knockdown of LOXL1-AS1 suppresses breast cancer cell migration and invasion. In vivo studies demonstrate that depletion of LOXL1-AS1 inhibits breast cancer metastasis. Mechanistically, LOXL1-AS1 sponges miR-708-5p to increase nuclear factor κB (NF-κB) activity. LOXL1-AS1 can also interact with EZH2 protein to enhance EZH2-mediated transcriptional repression of miR-708-5p. Rescue experiments indicate that co-expression of miR-708-5p attenuates LOXL1-AS1-induced invasiveness in breast cancer. In addition, there is a negative correlation between LOXL1-AS1 and miR-708-5p expression in breast cancer specimens. Overall, LOXL1-AS1 upregulation facilitates breast cancer invasion and metastasis by blocking miR-708-5p expression and activity. LOXL1-AS1 serves as a potential therapeutic target for breast cancer treatment.

Recent treatment progress of triple negative breast cancer

Breast cancer (BC) is a serious worldwide disease that threatens women's health. Particularly, the morbidity of triple-negative breast cancer (TNBC) is higher than that of other BC types due to its high molecular heterogeneity, metastatic potential and poor prognosis. TNBC lacks of estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER2), so there are still no effective treatment methods for TNBC. Here, we reviewed the classification of TNBC, its molecular mechanisms of pathogenesis, treatment methods and prognosis. Finding effective targets is critical for the treatment of TNBC. Also, refining the classification of TNBC is benefited to choose the treatment of TNBC, because the sensitivity of chemotherapy is different in different TNBC. Some new treatment methods have been proposed in recent years, such as nutritional therapy and noncoding RNA treatment methods. There are some disadvantages, such as the side effect on normal cells after nutrient deprivation, low specificity and instability of noncoding RNA. More studies are necessary to improve the treatment of TNBC.

Huaier Suppresses Breast Cancer Progression via linc00339/miR-4656/CSNK2B Signaling Pathway

Huaier, as known as Trametes robiniophila Murr, is a traditional Chinese medicine. Various studies have demonstrated that Huaier could inhibit cancer progression and improve the prognosis of patients. In the present study, we comprehensively screened the expression profiles of lncRNAs, miRNAs, and mRNAs in Huaier-treated breast cancer cells. Using bioinformatic analysis, hub genes were identified and functionally annotated. Weighted gene coexpression network analysis was applied to construct the molecular network influenced by Huaier. Linc00339 was then found to play a critical role in Huaier-mediated cancer suppression. To validate the effects of linc00339 and identify the downstream targets, we performed in vitro and in vivo experiments. Finally, we identified that Huaier could inhibit the proliferation of breast cancer cells through modulating linc00339/miR-4656/CSNK2B signaling pathway.

Circular RNA circVAPA Promotes Cell Proliferation in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is the most common malignancy in liver and is one of the leading causes of cancer-induced deaths all over the world. Circular RNAs (circRNAs) have been proven to be related to cancer initiation and progression in mounting reports. However, research on the role of circRNAs in human cancers, including HCC, is still in its infancy. circVAPA has been unmasked as oncogenic in colorectal cancer. Yet the function of circVAPA in HCC has never been elucidated. circVAPA, miR-377-3p, and prosaposin (PSAP) mRNA expression levels were detected by real-time quantitative PCR. PSAP protein levels were measured by Western blot. Cell proliferation was evaluated by CCK-8, colony formation, and EdU assays. Binding capacity was assessed by dual-luciferase reporter assay. circVAPA was upregulated in HCC cell lines and circVAPA depletion was associated with decreased HCC cell proliferation. circVAPA promotes PSAP expression through sequestering miR-377-3p. The suppression of HCC cell proliferation caused by circVAPA silence was revived by PSAP overexpression. This study revealed that circVAPA contributes to HCC cell proliferation through sponging miR-377-3p and thereby disinhibiting PSAP, shedding light on a new insight into HCC initiation and progression.

LINC00339 promotes growth and invasiveness of hepatocellular carcinoma by the miR-1182/SKA1 pathway

Background: Extensive research has shown that long noncoding RNA (lncRNA) is involved in tumorigenesis, including hepatocellular carcinoma (HCC). The lncRNA LINC00339 was reported to regulate the development of lung cancer or breast cancer. However, whether LINC00339 participates in HCC progression remains unclear. Here, our results showed that LINC00339 was upregulated in HCC.

Methods: qRT-PCR and in situ hybridization (ISH) was used to analyze LINC00339 expression in tumor tissues and cell lines. CCK8 and colony formation assays were used to analyze cell proliferation. Transwell assay was used to analyze cell migration and invasion. Xenograft experiment was used to test tumor growth in vivo.

Results: LINC00339 overexpression was correlated with an advanced stage, metastasis, and bad prognosis in HCC patients. Functional investigation showed that LINC00339 knockdown significantly suppressed HCC cell proliferation, migration, and invasion. Moreover, decreased LINC00339 expression inhibited HCC growth in vivo. Mechanistically, LINC00339 could interact with miR-1182 to promote SKA1 expression. We also demonstrated that SKA1 acted as an oncogene and SKA1 upregulation reversed the effect of LINC00339 silencing.

Conclusion: Our results illustrated that the LINC00339/miR-1182/SKA1 axis plays an essential role in HCC progression.