LncRNA DLX6-AS1 Contributes to Epithelial-Mesenchymal Transition and Cisplatin Resistance in Triple-negative Breast Cancer via Modulating Mir-199b-5p/Paxillin Axis

Exosomal ncRNAs in reproductive cancers†

Extracellular vesicles, particularly exosomes, play a pivotal role in the cellular mechanisms underlying cancer. This review explores the various functions of exosomes in the progression, growth, and metastasis of cancers affecting the male and female reproductive systems. Exosomes are identified as key mediators in intercellular communication, capable of transferring bioactive molecules such as microRNAs, proteins, and other nucleic acids that influence cancer cell behavior and tumor microenvironment interactions. It has been shown that non-coding RNAs transported by exosomes play an important role in tumor growth processes. Significant molecules that may serve as biomarkers in the development and progression of male reproductive cancers include miR-125a-5p, miR-21, miR-375, the miR-371 ~ 373 cluster, and miR-145-5p. For female reproductive cancers, significant microRNAs include miR-26a-5p, miR-148b, miR-205, and miRNA-423-3p. This review highlights the potential of these noncoding RNAs as biomarkers and prognostics in tumor diagnostics. Understanding the diverse roles of exosomes may hold promise for developing new therapeutic strategies and improving treatment outcomes for cancer patients.

The mechanism underlying metastasis in triple-negative breast cancer: focusing on the interplay between ferroptosis, epithelial-mesenchymal transition, and non-coding RNAs

Triple-negative breast cancer (TNBC) is a type of breast cancer with lack the expression of estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2). It is the most aggressive breast cancer and the most difficult to treat due to its poor response to treatments and extremely invasive characteristics. The typical treatment for TNBC frequently results in relapse because of the lack of particular treatment choices. It is urgent to focus on identifying a workable and effective target for the treatment of TNBC. Cancer metastasis is significantly influenced by epithelial-mesenchymal transition (EMT). Ferroptosis is an iron-dependent cell death form, and changes its key factor to affect the proliferation and metastasis of TNBC. Several reports have established associations between EMT and ferroptosis in TNBC metastasis. Furthermore, non-coding RNA (ncRNA), which has been previously described, can also control cancer cell death and metastasis. Thus, in this review, we summarize the correlation and pathways among the ferroptosis, EMT, and ncRNAs in TNBC metastasis. Also, aim to find out a novel strategy for TNBC treatment through the ncRNA-ferroptosis-EMT axis.

LncRNA-mediated regulation of cisplatin response in breast cancer

Breast cancer is a prevalent and aggressive disease characterized by high metastasis, recurrence, and mortality rates. While cisplatin is an effective chemotherapy drug, its use is limited by its toxic effects on the body. Despite advancements in therapeutic strategies, the therapeutic response is often unsatisfactory due to drug resistance, leading to poor prognosis. Recent studies have shown that cisplatin interacts with long non-coding RNAs (lncRNAs) and accelerates the development of resistance in tumor cells to therapy. This interaction highlights the complex mechanisms involved in the response of cancer cells to chemotherapy. Several lncRNAs have been identified as key players in mediating cisplatin resistance in breast cancer. These lncRNAs include SNHG15, HULC, HCP5, MT1JP, LncMat2B, DLX6-ASL, Linc00665, CARMN, and Lnc-EinRP44-3:6. These lncRNAs have been shown to target microRNAs and mRNAs and modulate the expression of genes involved in cisplatin resistance, which is important in treating breast cancer.

Targeted therapy approaches for epithelial-mesenchymal transition in triple negative breast cancer

Triple-negative breast cancer (TNBC) is distinguished by negative expression of estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2), making it an aggressive subtype of breast cancer and contributes to 15-20% of the total incidence. TNBC is a diverse disease with various genetic variations and molecular subtypes. The tumor microenvironment involves multiple cells, including immune cells, fibroblast cells, extracellular matrix (ECM), and blood vessels that constantly interact with tumor cells and influence each other. The ECM undergoes significant structural changes, leading to induced cell proliferation, migration, adhesion, invasion, and epithelial-to-mesenchymal transition (EMT). The involvement of EMT in the occurrence and development of tumors through invasion and metastasis in TNBC has been a matter of concern. Therefore, EMT markers could be prognostic predictors and potential therapeutic targets in TNBC. Chemotherapy has been one of the primary options for treating patients with TNBC, but its efficacy against TNBC is still limited. Targeted therapy is a critical emerging option with enhanced efficacy and less adverse effects on patients. Various targeted therapy approaches have been developed based on the specific molecules and the signaling pathways involved in TNBC. These include inhibitors of signaling pathways such as TGF-β, Wnt/β-catenin, Notch, TNF-α/NF-κB and EGFR, as well as immune checkpoint inhibitors, such as pembrolizumab, 2laparib, and talazoparib have been widely explored. This article reviews recent developments in EMT in TNBC invasion and metastasis and potential targeted therapy strategies.

Mechanistic insights into cisplatin response in breast tumors: Molecular determinants and drug/nanotechnology-based therapeutic opportunities

Breast cancer continues to be a major global health challenge, driving the need for effective therapeutic strategies. Cisplatin, a powerful chemotherapeutic agent, is widely used in breast cancer treatment. However, its effectiveness is often limited by systemic toxicity and the development of drug resistance. This review examines the molecular factors that influence cisplatin response and resistance, offering crucial insights for the scientific community. It highlights the significance of understanding cisplatin resistance's genetic and epigenetic contributors, which could lead to more personalized treatment approaches. Additionally, the review explores innovative strategies to counteract cisplatin resistance, including combination therapies, nanoparticle-based drug delivery systems, and targeted therapies. These approaches are under intensive investigation and promise to enhance breast cancer treatment outcomes. This comprehensive discussion is a valuable resource to advance breast cancer therapeutics and address the challenge of cisplatin resistance.

Decoding long non‑coding RNAs: Friends and foes in cancer development (Review)

Cancer remains a formidable adversary, challenging medical advancements with its dismal prognosis, low cure rates and high mortality rates. Within this intricate landscape, long non‑coding RNAs (lncRNAs) emerge as pivotal players, orchestrating proliferation and migration of cancer cells. Harnessing the potential of lncRNAs as therapeutic targets and prognostic markers holds immense promise. The present comprehensive review delved into the molecular mechanisms underlying the involvement of lncRNAs in the onset and progression of the top five types of cancer. By meticulously examining lncRNAs across diverse types of cancer, it also uncovered their distinctive roles, highlighting their exclusive oncogenic effects or tumor suppressor properties. Notably, certain lncRNAs demonstrate diverse functions across different cancers, confounding the conventional understanding of their roles. Furthermore, the present study identified lncRNAs exhibiting aberrant expression patterns in numerous types of cancer, presenting them as potential indicators for cancer screening and diagnosis. Conversely, a subset of lncRNAs manifests tissue‑specific expression, hinting at their specialized nature and untapped significance in diagnosing and treating specific types of cancer. The present comprehensive review not only shed light on the intricate network of lncRNAs but also paved the way for further research and clinical applications. The unraveled molecular mechanisms offer a promising avenue for targeted therapeutics and personalized medicine, combating cancer proliferation, invasion and metastasis.

Lau AT, Xu YM. The regulation of microRNAs on chemoresistance in triple-negative breast cancer: a recent update

Triple-negative breast cancer (TNBC) has negative expressions of ER, PR and HER2. Due to the insensitivity to both endocrine therapy and HER2-targeted therapy, the main treatment method for TNBC is cytotoxic chemotherapy. However, the curative effect of chemotherapy is limited because of the existence of acquired or intrinsic multidrug resistance. MicroRNAs (miRNAs) are frequently dysregulated in malignant tumors and involved in tumor occurrence and progression. Interestingly, growing studies show that miRNAs are involved in chemoresistance in TNBC. Thus, targeting dysregulated miRNAs could be a plausible way for better treatment of TNBC. Here, we present the updated knowledge of miRNAs associated with chemoresistance in TNBC, which may be helpful for the early diagnosis, prognosis and treatment of this life-threatening disease.

Long non-coding RNAs in drug resistance across the top five cancers: Update on their roles and mechanisms

Cancer drug resistance stands as a formidable obstacle in the relentless fight against the top five prevalent cancers: breast, lung, colorectal, prostate, and gastric cancers. These malignancies collectively account for a significant portion of cancer-related deaths worldwide. In recent years, long non-coding RNAs (lncRNAs) have emerged as pivotal players in the intricate landscape of cancer biology, and their roles in driving drug resistance are steadily coming to light. This comprehensive review seeks to underscore the paramount significance of lncRNAs in orchestrating resistance across a spectrum of different cancer drugs, including platinum drugs (DDP), tamoxifen, trastuzumab, 5-fluorouracil (5-FU), paclitaxel (PTX), and Androgen Deprivation Therapy (ADT) across the most prevalent types of cancer. It delves into the multifaceted mechanisms through which lncRNAs exert their influence on drug resistance, shedding light on their regulatory roles in various facets of cancer biology. A comprehensive understanding of these lncRNA-mediated mechanisms may pave the way for more effective and personalized treatment strategies, ultimately improving patient outcomes in these challenging malignancies.

Genomic Alterations Affecting Competitive Endogenous RNAs (ceRNAs) and Regulatory Networks (ceRNETs) with Clinical Implications in Triple-Negative Breast Cancer (TNBC)

The concept of competitive endogenous RNA regulation has brought on a change in the way we think about transcriptional regulation by miRNA-mRNA interactions. Rather than the relatively simple idea of miRNAs negatively regulating mRNA transcripts, mRNAs and other non-coding RNAs can regulate miRNAs and, therefore, broad networks of gene products through competitive interactions. While this concept is not new, its significant roles in and implications on cancer have just recently come to light. The field is now ripe for the extrapolation of technologies with a substantial clinical impact on cancer. With the majority of the genome consisting of non-coding regions encoding regulatory RNAs, genomic alterations in cancer have considerable effects on these networks that have been previously unappreciated. Triple-negative breast cancer (TNBC) is characterized by high mutational burden, genomic instability and heterogeneity, making this aggressive breast cancer subtype particularly relevant to these changes. In the past few years, much has been learned about the roles of competitive endogenous RNA network regulation in tumorigenesis, disease progression and drug response in triple-negative breast cancer. In this review, we present a comprehensive view of the new knowledge and future perspectives on competitive endogenous RNA networks affected by genomic alterations in triple-negative breast cancer. An overview of the competitive endogenous RNA (ceRNA) hypothesis and its bearing on cellular function and disease is provided, followed by a thorough review of the literature surrounding key competitive endogenous RNAs in triple-negative breast cancer, the genomic alterations affecting them, key disease-relevant molecular and functional pathways regulated by them and the clinical implications and significance of their dysregulation. New knowledge of the roles of these regulatory mechanisms and the current acceleration of research in the field promises to generate insights into the diagnosis, classification and treatment of triple-negative breast cancer through the elucidation of new molecular mechanisms, therapeutic targets and biomarkers.

Long noncoding RNAs as regulators of epithelial mesenchymal transition in breast cancer: A recent review

AIMS

Breast cancer (BC) is the most frequently occurring cancer in women worldwide. BC patients are often diagnosed at advanced stages which are characterized by low survival rates. Distant metastasis is considered a leading cause of mortalities among BC patients. Epithelial-to-mesenchymal transition (EMT) is a transdifferentiation program that is necessary for cancer cells to acquire metastatic potential. In the last decade, long noncoding RNAs (lncRNAs) proved their significant contribution to different hallmarks of cancer, including EMT and metastasis. The primary aim of our review is to analyze recent studies concerning the molecular mechanisms of lncRNAs implicated in EMT regulation in BC.

MATERIALS AND METHODS

We adopted a comprehensive search on databases of PubMed, Web of Science, and Google Scholar using the following keywords: lncRNAs, EMT, breast cancer, and therapeutic targeting.

KEY FINDINGS

The different roles of lncRNAs in the mechanisms and signaling pathways governing EMT in BC were summarized. LncRNAs could induce or inhibit EMT through WNT/β-catenin, transforming growth factor-β (TGF-β), Notch, phosphoinositide 3-kinase/protein kinase B (PI3K/AKT), signal transducer and activator of transcription 3 (STAT3), and nuclear factor kappa B (NF-κB) pathways as well as via their interaction with histone modifying complexes and miRNAs.

SIGNIFICANCE

LncRNAs are key regulators of EMT and BC metastasis, presenting potential targets for therapeutic interventions. Further research is necessary to investigate the practical application of lncRNAs in clinical therapeutics.

Exploration of epithelial-mesenchymal transition-related lncRNA signature and drug sensitivity in breast cancer

Background

Breast cancer (BRCA) has become the most diagnosed cancer worldwide for female and seriously endanger female health. The epithelial-mesenchymal transition (EMT) process is associated with metastasis and drug resistance in BRCA patients. However, the prognostic value of EMT-related lncRNA in BRCA still needs to be revealed. The aim of this study is to construct an EMT-related lncRNA (ERL) signature with accuracy predictive ability for the prognosis of BRCA patients.

Methods

RNA-seq expression data and Clinical characteristics obtained from the TCGA (The Cancer Genome Atlas) were used in the study. First, we identified the EMT-related lncRNA by the Pearson correlation analysis. An EMT-related lncRNAs prognostic risk signature was constructed using univariate Cox regression and Lasso-penalized Cox regression analyses. The model's performance was validated using Kaplan-Meier (KM) survival analysis, ROC curve and C-index. Finally, a nomogram was constructed for clinical practice in evaluating the patients with BRCA and validated by calibration curve and decision curve analysis (DCA). We also evaluated the drug sensitivity of signature lncRNA and the tumor immune cell infiltration in breast cancer.

Results

We constructed a 10-lncRNA risk score signature based on the lncRNAs associated with the EMT process. We could assign BRCA patients to the high- and low-risk group according to the median risk score. The prognostic risk signature showed excellent accuracy and demonstrated sufficient independence from other clinical characteristics. The immune cell infiltration analysis showed that the prognostic risk signature was related to the infiltration of the immune cell subtype. Drug sensitivity analysis proved ERLs signature could effectively predict the sensitivity of patients to common chemotherapy drugs in BRCA and provide guidance for chemotherapy drugs for high-risk and low-risk patients.

Conclusion

Our ERL signature and nomogram have excellent prognostic value and could become reliable tools for clinical guidance.

The Role of Paxillin Aberrant Expression in Cancer and Its Potential as a Target for Cancer Therapy

Paxillin is a multi-domain adaptor protein. As an important member of focal adhesion (FA) and a participant in regulating cell movement, paxillin plays an important role in physiological processes such as nervous system development, embryonic development, and vascular development. However, increasing evidence suggests that paxillin is aberrantly expressed in many cancers. Many scholars have also recognized that the abnormal expression of paxillin is related to the prognosis, metastases, invasion, survival, angiogenesis, and other aspects of malignant tumors, suggesting that paxillin may be a potential cancer therapeutic target. Therefore, the study of how aberrant paxillin expression affects the process of tumorigenesis and metastasis will help to develop more efficacious antitumor drugs. Herein, we review the structure of paxillin and its function and expression in tumors, paying special attention to the multifaceted effects of paxillin on tumors, the mechanism of tumorigenesis and progression, and its potential role in tumor therapy. We also hope to provide a reference for the clinical prognosis and development of new tumor therapeutic targets.

Interplay between LncRNAs and microRNAs in Breast Cancer

(1) Although long noncoding RNAs (lncRNAs) are known to be precursors of microRNAs (miRNAs), they frequently act as competing endogoneous RNAs (ceRNAs), yet still their interplay with miRNA is not well known. However, their interaction with miRNAs may result in the modulation of miRNA action. (2) To determine the contribution of these RNA molecules in tumor resistance to chemotherapeutic drugs, it is essential to consider not only the oncogenic and tumor suppressive function of miRNAs but also the impact of lncRNAs on miRNAs. Therefore, we performed an extensive search in different databases including PubMed. (3) The present study concerns the interplay between lncRNAs and miRNAs in the regulatory post-transcriptional network and their impact on drugs used in the treatment of breast cancer. (4) Consideration of this interplay may improve the search for new drugs to circumvent chemoresistance.

The Clinical Utility of lncRNAs and Their Application as Molecular Biomarkers in Breast Cancer

Given their tumor-specific and stage-specific gene expression, long non-coding RNAs (lncRNAs) have demonstrated to be potential molecular biomarkers for diagnosis, prognosis, and treatment response. Particularly, the lncRNAs DSCAM-AS1 and GATA3-AS1 serve as examples of this because of their high subtype-specific expression profile in luminal B-like breast cancer. This makes them candidates to use as molecular biomarkers in clinical practice. However, lncRNA studies in breast cancer are limited in sample size and are restricted to the determination of their biological function, which represents an obstacle for its inclusion as molecular biomarkers of clinical utility. Nevertheless, due to their expression specificity among diseases, such as cancer, and their stability in body fluids, lncRNAs are promising molecular biomarkers that could improve the reliability, sensitivity, and specificity of molecular techniques used in clinical diagnosis. The development of lncRNA-based diagnostics and lncRNA-based therapeutics will be useful in routine medical practice to improve patient clinical management and quality of life.

Paxillin is a potential prognostic biomarker associated with immune cell infiltration in ovarian cancer

Objective

To investigate the expression, prognosis, and underlying mechanism of Paxillin (PXN) in ovarian cancer.

Materials and methods

By comprehensive use of various bioinformatics tools, we analyzed the expression of PXN and its prognostic value in ovarian cancer. Then, the enrichment analyses were conducted to determine the possible regulatory pathways PXN involved in ovarian cancer. Finally, the associations of PXN expression with immune cell infiltration and immune checkpoints were analyzed.

Results

PXN was highly expressed in ovarian cancer and its expression could independently predict the overall survival of ovarian cancer patients. More importantly, PXN had a superior ability in predicting long-term survival than age and tumor residual disease in ovarian cancer patients. In addition, PXN was positively related to adherens junction and tight junction pathways. Significant negative relationships between PXN expression and immune infiltrates were observed, however, PXN was positively connected with immune checkpoint (VSIR) in ovarian cancer.

Conclusions

PXN serves as a reliable prognostic biomarker and may be a potent therapeutic target for ovarian cancer. Moreover, high PXN expression may affect ovarian cancer progression via positive regulation of metastasis-related pathways.

Long non-coding RNA DLX6-AS1 is the key mediator of glomerular podocyte injury and albuminuria in diabetic nephropathy by targeting the miR-346/GSK-3β signaling pathway

Progressive albuminuria is the primary clinical symptom of diabetic nephropathy (DN), leading to a gradual decline in kidney function. DLX6-AS1 was the first reported long non-coding RNA (lncRNA) to participate in organogenesis and play crucial roles in the brain or neural cell development. Herein, we investigated the DLX6-AS1 (Dlx6-os1 in mice) role in DN pathogenesis. We found that DLX6-AS1 expression in DN patients correlated with the extent of albuminuria. Dlx6-os1 overexpression induced cellular damage and inflammatory responses in cultured podocytes through miR-346-mediated regulation of the GSK-3β pathway. In various established diabetic and newly developed knockout mouse models, Dlx6-os1 knockdown/knockout significantly reduced podocyte injury and albuminuria. The Dlx6-os1 effects were remarkably modulated by miR-346 mimics or mutants and significantly diminished in podocyte-specific GSK-3β-knockout mice. Thus, DLX6-AS1 (Dlx6-os1) promotes DN development by accelerating podocyte injury and inflammation through the upregulation of the GSK-3β pathway, providing a novel molecular target for DN therapy.

Metformin and long non-coding RNAs in breast cancer

Breast cancer (BC) is the second most common cancer and cause of death in women. In recent years many studies investigated the association of long non-coding RNAs (lncRNAs), as novel genetic factors, on BC risk, survival, clinical and pathological features. Recent studies also investigated the roles of metformin treatment as the firstline treatment for type 2 diabetes (T2D) played in lncRNAs expression/regulation or BC incidence, outcome, mortality and survival, separately. This comprehensive study aimed to review lncRNAs associated with BC features and identify metformin-regulated lncRNAs and their mechanisms of action on BC or other types of cancers. Finally, metformin affects BC by regulating five BC-associated lncRNAs including GAS5, HOTAIR, MALAT1, and H19, by several molecular mechanisms have been described in this review. In addition, metformin action on other types of cancers by regulating ten lncRNAs including AC006160.1, Loc100506691, lncRNA-AF085935, SNHG7, HULC, UCA1, H19, MALAT1, AFAP1-AS1, AC026904.1 is described.

Characterization of protein-based risk signature to predict prognosis and evaluate the tumor immune environment in breast cancer

BACKGROUND

Proteomics profiles have enabled a systematic insight into the prognosis of cancer. This study aimed to establish a valuable protein-based risk signature to assess the prognosis and immune status in patients with breast cancer (BC).

METHODS

Protein expression profile, RNA expression data, and clinical information were acquired from The Cancer Genome Atlas (TCGA). The whole cohort was randomly split into two cohorts, one for establishing the risk signature and the other for testing. Univariate Cox analysis and Least absolute shrinkage and selection operator (LASSO) Cox regression were utilized to construct the protein-based risk signature. All cohorts were divided into high- and low-risk groups, which were applied to investigate the clinical relevance, tumor microenvironment, and therapeutic response.

RESULTS

The prognostic proteomics signature was established based on prognostic proteins, thus categorizing patients into low-risk and high-risk groups with different prognoses. A predictive nomogram was also developed to predict 1, 3, and 5-year survival possibility for BC patients, and the calibration curves confirmed the predictive significance of this signature. Afterward, the low-risk group displayed higher immune activities, immune checkpoint expression, and immunotherapeutic response. Moreover, GSEA analysis indicated that immune-associated pathways were rich in the low-risk group. Additionally, this prognostic signature demonstrated potential predict significance for chemotherapeutic agents.

CONCLUSION

This study established an effective prognostic proteomics signature with reliable predictive performance for survival, immune activity, and drug sensitivity. It might provide a novel perspective into the protein function in BC, and guide the individual treatment strategies for BC patients.

Tamoxifen resistance-related ceRNA network for breast cancer

Background: Tamoxifen (TMX) is one of the most widely used drugs to treat breast cancer (BC). However, acquired drug resistance is still a major obstacle to its application, rendering it crucial to explore the mechanisms of TMX resistance in BC. This aims of this study were to identify the mechanisms of TMX resistance and construct ceRNA regulatory networks in breast cancer. Methods: GEO2R was used to screen for differentially expressed mRNAs (DEmRNAs) leading to drug resistance in BC cells. MiRTarbase and miRNet were used to predict miRNAs and lncRNAs upstream, and the competing endogenous RNA (ceRNA) regulatory network of BC cell resistance was constructed by starBase. We used the Kaplan-Meier plotter and Gene Expression Profiling Interactive Analysis (GEPIA) to analyze the expression and prognostic differences of genes in the ceRNA network with core axis, and qRT-PCR was used to further verify the above conclusions. Results: We found that 21 DEmRNAs were upregulated and 43 DEmRNA downregulated in drug-resistant BC cells. DEmRNAs were noticeably enriched in pathways relevant to cancer. We then constructed a protein-protein interaction (PPI) network based on the STRING database and defined 10 top-ranked hub genes among the upregulated and downregulated DEmRNAs. The 20 DEmRNAs were predicted to obtain 113 upstream miRNAs and 501 lncRNAs. Among them, 7 mRNAs, 22 lncRNAs, and 11 miRNAs were used to structure the ceRNA regulatory network of drug resistance in BC cells. 4 mRNAs, 4 lncRNAs, and 3 miRNAs were detected by GEPIA and the Kaplan-Meier plotter to be significantly associated with BC expression and prognosis. The differential expression of the genes in BC cells was confirmed by qRT-PCR. Conclusion: The ceRNA regulatory network of TMX-resistant BC was successfully constructed and confirmed. This will provide an important resource for finding therapeutic targets for TMX resistance, where the discovery of candidate conventional mechanisms can aid clinical decision-making. In addition, this resource will help discover the mechanisms behind this type of resistance.

Docetaxel-resistant triple-negative breast cancer cell-derived exosomal lncRNA LINC00667 reduces the chemosensitivity of breast cancer cells to docetaxel <em>via</em> targeting miR-200b-3p/Bcl-2 axis

Development of docetaxel (TXT) resistance is a major obstacle for triple-negative breast cancer (TNBC) treatment. Additionally, chemoresistant cell-derived exosomes were able to change the chemo-response of chemosensitive recipient cells via transportation of lncRNAs. It has been shown that lncRNA LINC00667 level was significantly elevated in breast cancer tissues. Therefore, we explored whether LINC00667 level is increased in TXT-resistant TNBC cell-derived exosomes. In addition, whether exosomal LINC00667 derived from TXT-resistant TNBC cell could affect TXT sensitivity in TXT-sensitive TNBC cells was investigated as well. In the present study, exosomes were isolated from the TXT-resistant TNBC cells and from TXT-sensitive TNBC cells. Next, the level of LINC00667 in the isolated exosomes was detected with RT-qPCR. We found that LINC00667 expression was obviously elevated in TXT-resistant TNBC cell-derived exosomes compared to that in TXT-sensitive TNBC cell-derived exosomes. In addition, LINC00667 could be transferred from TXT-resistant TNBC cells to TNBC cells via exosomes. Moreover, TXT-resistant TNBC cell secreted exosomal LINC00667 markedly reduced the sensitivity of TNBC cells to TXT via upregulation of Bcl-2. Meanwhile, downregulation of LINC00667 notably enhanced the sensitivity of TXT-resistant TNBC cells to TXT through downregulation of Bcl-2. Additionally, LINC00667 was considered to be a ceRNA to sponge miR-200b-3p, thereby elevating Bcl-2 expression. Collectively, TXT-resistant TNBC cell-derived exosomal LINC00667 could decrease the chemosensitivity of TNBC cells to TXT via regulating miR-200b-3p/Bcl-2 axis. These findings suggested that LINC00667 might serve as a promising target for enhancing sensitivity of TNBC cells to TXT therapy.

Non-coding RNAs, another side of immune regulation during triple-negative breast cancer

Triple-negative breast cancer (TNBC) is considered about 12-24 % of all breast cancer cases. Patients experience poor overall survival, high recurrence rate, and distant metastasis compared to other breast cancer subtypes. Numerous studies have highlighted the crucial roles of non-coding RNAs (ncRNAs) in carcinogenesis and proliferation, migration, and metastasis of tumor cells in TNBC. Recent research has demonstrated that long non-coding RNAs (lncRNAs) and microRNAs (miRNAs) play a role in the regulation of the immune system by affecting the tumor microenvironment, the epithelial-mesenchymal transition, the regulation of dendritic cells and myeloid-derived stem cells, and T and B cell activation and differentiation. Immune-related miRNAs and lncRNAs, which have been established as predictive markers for various cancers, are strongly linked to immune cell infiltration and could be a viable therapeutic target for TNBC. In the current review, we discuss the recent updates of ncRNAs, including miRNAs and lncRNAs in TNBC, including their biogenesis, target genes, and biological function of their targets, which are mostly involved in the immune response.

Strategies of LncRNA DLX6-AS1 on Study and Therapeutics

Accumulating evidence has revealed the vital regulatory roles of lncRNA DLX6-AS1 in various tumors at pre-transcriptional, transcriptional, and post-transcriptional levels, which makes it a potential prognosis factor and therapeutic target. In addition, the presence of lncRNA DLX6-AS1 in the exosomes of peripheral blood of patients with tumors may also contribute to it being a possible cancer-related biomarker. However, most literature studies are devoted to studying the effect of lncRNA DLX6-AS1 as a sponging molecule of miRNAs, the research of which is likely to get stuck into a dilemma. Literature studies published already have demonstrated an exciting cell malignant phenotype inhibition with the knockdown of lncRNA DLX6-AS1 in various tumor cell lines. With the comprehensive development of delivery systems, high-throughput sequencing, and aptamers, the problems of finding novel research methods and exploring the therapeutic options which are based on lncRNA DLX6-AS1 in vivo could come into a period to deal with. This review aims to summarize the research statuses of lncRNA DLX6-AS1, discuss other study methodologies and therapeutic strategies on it, which might be of help to the deep learning of lncRNA DLX6-AS1 and its application from basic to clinical research.

LncRNA DLX6-AS1 promotes microglial inflammatory response in Parkinson's disease by regulating the miR-223-3p/NRP1 axis

Parkinson's disease (PD) is a prevailing neurodegenerative disorder. This study discussed the mechanism of lncRNA distal-less homeobox 6 antisense 1 (DLX6-AS1) on inflammatory responses in PD. With healthy male C57BL/6 mice (8-10 weeks) and BV2 microglia as study subjects, we established PD models in vivo/in vitro by injection of 1-methyl-4-phenyl-2, 3, 6-tetrahydropyridine (MPTP) for 4 weeks and treatment of lipopolysaccharide (LPS) for 24hours, respectively. DLX6-AS1 expression in PD mice and BV2 microglia was examined using reverse transcription quantitative-polymerase chain reaction and then down-regulated via stereotaxic catheter injection or cell transfection to evaluate its effect on neurological function. Meanwhile, the cell number of TH+/Caspase3+/IBA1+ in substantia nigra, cell viability, and apoptosis rate of BV2 microglia, inflammatory levels, and NLR family pyrin domain containing 3 (NLRP3) inflammasome were determined using immunohistochemistry, MTT assay, flow cytometry, ELISA assay, and Western blot. The binding relationship between miR-223-3p and DLX6-AS1/Neuropilin-1 (NRP1) was verified by dual-luciferase assay and RNA immunoprecipitation assay. After down-regulation of DLX6-AS1, we down-regulated/overexpressed miR-223-3p/NRP1 levels in BV2 microglia. DLX6-AS1 was overexpressed in PD mice. Silencing DLX6-AS1 improved neurological function and alleviated microglial inflammation in PD mice. Specifically, the latency of mice falling from the rotating rod was longer, and the latency of climbing rod test was shorter; TH+ cells increased, while Caspase3+/IBA1+ cells decreased; the levels of inflammatory were lowered. Silencing DLX6-AS1 inhibited LPS-induced inflammation of BV2 microglia. DLX6-AS1 acted as the ceRNA of miR-223-3p to promote NRP1. Down-regulation of miR-223-3p or overexpression of NRP1 partially annulled the effect of silencing DLX6-AS1 on BV2 microglial inflammation. Overall, DLX6-AS1 promotes the microglial inflammatory response in PD through the ceRNA mechanism of miR-223-3p/NRP1.

Yin Yang 1-induced activation of LINC01133 facilitates the progression of pancreatic cancer by sponging miR-199b-5p to upregulate myelin regulatory factor expression

Increasing evidence has reported that long non-coding RNA (lncRNA) plays a vital role in the development of pancreatic cancer (PC). However, the function and mechanism of LINC01133 in PC tumorigenesis are still unknown. Herein, we found that LINC01133 was highly expressed in PC tissues and cell lines, and LINC01133 knockdown could block the growth and metastasis of PC cells. Besides, upregulated LINC01133 in PC cells was induced by Yin Yang 1 (YY1). Furthermore, LINC01133 directly targeted miR-199b-5p and promoted cancer malignancy by suppressing miR-199b-5p. It was also discovered that myelin regulatory factor (MYRF) was targeted by miR-199b-5p and positively correlated with LINC01133 expression in PC, and LINC01133 modulated PC progression through miR-199b-5p/MYRF pathway. In conclusion, we demonstrated that YY1-mediated the upregulation of LINC0113 increased MYRF expression by sponging miR-199b-5p, resulting in the accelerated development of PC. These findings might offer a novel insight into the development of efficient therapeutics for PC patients.

The Mechanisms of lncRNA-Mediated Multidrug Resistance and the Clinical Application Prospects of lncRNAs in Breast Cancer

Simple Summary

Multidrug resistance (MDR) is a major cause of breast cancer (BC) chemotherapy failure. Long noncoding RNAs (lncRNAs) have been shown closely related to the chemoresistance of BC. In this work, the mechanisms of lncRNA-mediated MDR in BC were elaborated from eight sections, including apoptosis, autophagy, DNA repair, cell cycle, drug efflux, epithelial-mesenchymal transition, epigenetic modification and the tumor microenvironment. Additionally, we also discuss the clinical significance of lncRNAs, which may be biomarkers for diagnosis, therapy and prognosis.

Abstract

Breast cancer (BC) is a highly heterogeneous disease and presents a great threat to female health worldwide. Chemotherapy is one of the predominant strategies for the treatment of BC; however, multidrug resistance (MDR) has seriously affected or hindered the effect of chemotherapy. Recently, a growing number of studies have indicated that lncRNAs play vital and varied roles in BC chemoresistance, including apoptosis, autophagy, DNA repair, cell cycle, drug efflux, epithelial-mesenchymal transition (EMT), epigenetic modification and the tumor microenvironment (TME). Although thousands of lncRNAs have been implicated in the chemoresistance of BC, a systematic review of their regulatory mechanisms remains to be performed. In this review, we systematically summarized the mechanisms of MDR and the functions of lncRNAs mediated in the chemoresistance of BC from the latest literature. These findings significantly enhance the current understanding of lncRNAs and suggest that they may be promising prognostic biomarkers for BC patients receiving chemotherapy, as well as therapeutic targets to prevent or reverse chemoresistance.

Contribution of MicroRNAs in Chemoresistance to Cisplatin in the Top Five Deadliest Cancer: An Updated Review

Cisplatin (DDP) is a well-known anticancer drug used for the treatment of numerous human cancers in solid organs, including bladder, breast, cervical, head and neck squamous cell, ovarian, among others. Its most important mode of action is the DNA-platinum adducts formation, inducing DNA damage response, silencing or activating several genes to induce apoptosis; these mechanisms result in genetics and epigenetics modifications. The ability of DDP to induce tumor cell death is often challenged by the presence of anti-apoptotic regulators, leading to chemoresistance, wherein many patients who have or will develop DDP-resistance. Cancer cells resist the apoptotic effect of chemotherapy, being a problem that severely restricts the successful results of treatment for many human cancers. In the last 30 years, researchers have discovered there are several types of RNAs, and among the most important are non-coding RNAs (ncRNAs), a class of RNAs that are not involved in protein production, but they are implicated in gene expression regulation, and representing the 98% of the human genome non-translated. Some ncRNAs of great interest are long ncRNAs, circular RNAs, and microRNAs (miRs). Accumulating studies reveal that aberrant miRs expression can affect the development of chemotherapy drug resistance, by modulating the expression of relevant target proteins. Thus, identifying molecular mechanisms underlying chemoresistance development is fundamental for setting strategies to improve the prognosis of patients with different types of cancer. Therefore, this review aimed to identify and summarize miRs that modulate chemoresistance in DDP-resistant in the top five deadliest cancer, both in vitro and in vivo human models.

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.

DLX6-AS1: A Long Non-coding RNA With Oncogenic Features

Long non-coding RNAs (lncRNAs) are a heterogeneous group of ncRNAs with characteristic size of more than 200 nucleotides. An increasing number of lncRNAs have been found to be dysregulated in many human diseases particularly cancer. However, their role in carcinogenesis is not precisely understood. DLX6-AS1 is an lncRNAs which has been unveiled to be up-regulated in various number of cancers. In different cell studies, DLX6-AS1 has shown oncogenic role via promoting oncogenic phenotype of cancer cell lines. Increase in tumor cell proliferation, migration, invasion, and EMT while suppressing apoptosis in cancer cells are the effects of DLX6-AS1 in development and progression of cancer. In the majority of cell experiment, mediator miRNAs have been identified which are sponged and negatively regulated by DLX6-AS1, and they in turn regulate expression of a number of transcription factors, eventually affecting signaling pathways involved in carcinogenesis. These pathways form axes through which DLX6-AS1 promotes carcinogenicity of cancer cells. Xenograft animal studies, also have confirmed enhancing effect of DLX6-AS1 on tumor growth and metastasis. Clinical evaluations in cancerous patients have also shown increased expression of DLX6-AS1 in tumor tissues compared to healthy tissues. High DLX6-AS1 expression has shown positive association with advanced clinicopathological features in cancerous patients. Survival analyses have demonstrated correlation between high DLX6-AS1 expression and shorter survival. In cox regression analysis, DLX6-AS1 has been found as an independent prognostic factor for patients with various types of cancer.

Molecular Mechanisms, Biomarkers and Emerging Therapies for Chemotherapy Resistant TNBC

Triple-negative breast cancer (TNBC) is associated with high recurrence rates, high incidence of distant metastases, and poor overall survival (OS). Taxane and anthracycline-containing chemotherapy (CT) is currently the main systemic treatment option for TNBC, while platinum-based chemotherapy showed promising results in the neoadjuvant and metastatic settings. An early arising of intrinsic or acquired CT resistance is common and represents the main hurdle for successful TNBC treatment. Numerous mechanisms were uncovered that can lead to the development of chemoresistance. These include cancer stem cells (CSCs) induction after neoadjuvant chemotherapy (NACT), ATP-binding cassette (ABC) transporters, hypoxia and avoidance of apoptosis, single factors such as tyrosine kinase receptors (EGFR, IGFR1), a disintegrin and metalloproteinase 10 (ADAM10), and a few pathological molecular pathways. Some biomarkers capable of predicting resistance to specific chemotherapeutic agents were identified and are expected to be validated in future studies for a more accurate selection of drugs to be employed and for a more tailored approach, both in neoadjuvant and advanced settings. Recently, based on specific biomarkers, some therapies were tailored to TNBC subsets and became available in clinical practice: olaparib and talazoparib for BRCA1/2 germline mutation carriers larotrectinib and entrectinib for neurotrophic tropomyosin receptor kinase (NTRK) gene fusion carriers, and anti-trophoblast cell surface antigen 2 (Trop2) antibody drug conjugate therapy for heavily pretreated metastatic TNBC (mTNBC). Further therapies targeting some pathologic molecular pathways, apoptosis, miRNAS, epidermal growth factor receptor (EGFR), insulin growth factor 1 receptor (IGF-1R), and androgen receptor (AR) are under investigation. Among them, phosphatidylinositol 3 kinase (PI3K)/protein kinase B (Akt)/mammalian target of rapamycin (mTOR) and EGFR inhibitors as well as antiandrogens showed promising results and are under evaluation in Phase II/III clinical trials. Emerging therapies allow to select specific antiblastics that alone or by integrating the conventional therapeutic approach may overcome/hinder chemoresistance.

Identification of miR-199-5p and miR-199-3p Target Genes: Paxillin Facilities Cancer Cell Aggressiveness in Head and Neck Squamous Cell Carcinoma

Our previous study revealed that the miR-199 family (miR-199a-5p/-3p and miR-199b-5p/-3p) acts as tumor-suppressive miRNAs in head and neck squamous cell carcinoma (HNSCC). Furthermore, recent studies have indicated that the passenger strands of miRNAs are involved in cancer pathogenesis. The aim of this study was to identify cancer-promoting genes commonly regulated by miR-199-5p and miR-199-3p in HNSCC cells. Our in silico analysis and luciferase reporter assay identified paxillin (PXN) as a direct target of both miR-199-5p and miR-199-3p in HNSCC cells. Analysis of the cancer genome atlas (TCGA) database showed that expression of PXN significantly predicted a worse prognosis (5-year overall survival rate; p = 0.0283). PXN expression was identified as an independent factor predicting patient survival according to multivariate Cox regression analyses (p = 0.0452). Overexpression of PXN was detected in HNSCC clinical specimens by immunostaining. Functional assays in HNSCC cells showed that knockdown of PXN expression attenuated cancer cell migration and invasion, suggesting that aberrant expression of PXN contributed to HNSCC cell aggressiveness. Our miRNA-based approach will provide new insights into the molecular pathogenesis of HNSCC.

DLX6-AS1: a putative lncRNA candidate in multiple human cancers

Long non-coding RNAs (lncRNAs) have important roles in regulating the expression of genes and act as biomarkers in the initial development of different cancers. Increasing research studies have verified that dysregulation of lncRNAs occurs in various pathological processes including tumorigenesis and cancer progression. Among the different lncRNAs, DLX6-AS1 has been reported to act as an oncogene in the development and prognoses of different cancers, by affecting many different signalling pathways. This review summarises and analyses the recent research studies describing the biological functions of DLX6-AS1, its overall effect on signalling pathways and the molecular mechanisms underlying its action on the expression of genes in multiple human cancers. Our critical analysis suggests that different signalling pathways associated to this lncRNA may be used as a biomarker for diagnosis, or targets of treatment in cancers.

The curcumin analog EF24 inhibits proliferation and invasion of triple-negative breast cancer cells by targeting the lncRNA HCG11/Sp1 axis

EF24, a curcumin analog, exerts a potent anti-tumor effect on various cancers. However, whether EF24 retards the progression of triple-negative breast cancer (TNBC) remains unclear. In this study, we explored the role of EF24 in TNBC and clarified the underlying mechanism. In a mouse model of TNBC xenograft, EF24 administration reduced the tumor volume, suppressed cell proliferation, promoted cell apoptosis, and downregulated long non-coding RNA human leukocyte antigen complex group 11 (HCG11) expression. In TNBC cell lines, EF24 administration reduced cell viability, suppressed cell invasion, and downregulated HCG11 expression. HCG11 overexpression re-enhanced the proliferation and invasion of TNBC cell lines suppressed by EF24. The following mechanism research revealed that HCG11 overexpression elevated Sp1 transcription factor (Sp1) expression by reducing its ubiquitination, thereby enhanced Sp1-mediated cell survival and invasion in the TNBC cell line. Finally, the in vivo study showed that HCG11-overexpressed TNBC xenografts exhibited lower responsiveness in response to EF24 treatment. In conclusion, EF24 treatment reduced HCG11 expression, resulting in the degradation of Sp1 expression, thereby inhibiting the proliferation and invasion of TNBC cells.

Research progress of DLX6-AS1 in human cancers

Long non-coding RNAs (lncRNAs) are a kind of translational-repressor RNAs composed of more than 200 nucleotides and formerly considered as "transcriptional noise". Recently studies have shown that lncRNAs could bind to multiple biomolecules such as DNA, transcription factors, RNA, chromatin complexes and proteins, and regulate target gene expression at multi-levels, thus playing an essential role in human tumors. DLX6-AS1, a recently discovered oncogenic lncRNA, is highly expressed in various human tumors, including lung cancer, liver cancer and pancreatic cancer. This paper mainly reviewed the regulatory mechanism of DLX6-AS1 as a competitive endogenous RNA (ceRNA) in tumor cell proliferation, cell apoptosis, angiogenesis, epithelial-mesenchymal transformation, chemotherapy resistance and metabolic changes. Furthermore, the translational value of DLX6-AS1 in cancer was also elucidated, which suggested its potential as a diagnostic or prognostic biomarker in cancer. In summary, this present article not only makes an in-depth analysis of the expression changes and carcinogenic mechanism of DLX6-AS1 in various human cancers, but also provides a new breakthrough for the diagnosis and treatment of cancers.

The regulatory role of antisense lncRNAs in cancer

Antisense long non-coding RNAs (antisense lncRNAs), transcribed from the opposite strand of genes with either protein coding or non-coding function, were reported recently to play a crucial role in the process of tumor onset and development. Functionally, antisense lncRNAs either promote or suppress cancer cell proliferation, migration, invasion, and chemoradiosensitivity. Mechanistically, they exert their regulatory functions through epigenetic, transcriptional, post-transcriptional, and translational modulations. Simultaneously, because of nucleotide sequence complementarity, antisense lncRNAs have a special role on its corresponding sense gene. We highlight the functions and molecular mechanisms of antisense lncRNAs in cancer tumorigenesis and progression. We also discuss the potential of antisense lncRNAs to become cancer diagnostic biomarkers and targets for tumor treatment.

Keep your eyes peeled for long noncoding RNAs: Explaining their boundless role in cancer metastasis, drug resistance, and clinical application

Cancer metastasis and drug resistance are two major obstacles in the treatment of cancer and therefore, the leading cause of cancer-associated mortalities worldwide. Hence, an in-depth understanding of these processes and identification of the underlying key players could help design a better therapeutic regimen to treat cancer. Earlier thought to be merely transcriptional junk and having passive or secondary function, recent advances in the genomic research have unravelled that long noncoding RNAs (lncRNAs) play pivotal roles in diverse physiological as well as pathological processes including cancer metastasis and drug resistance. LncRNAs can regulate various steps of the complex metastatic cascade such as epithelial-mesenchymal transition (EMT), invasion, migration and metastatic colonization, and also affect the sensitivity of cancer cells to various chemotherapeutic drugs. A substantial body of literature for more than a decade of research evince that lncRNAs can regulate gene expression at different levels such as epigenetic, transcriptional, posttranscriptional, translational and posttranslational levels, depending on their subcellular localization and through their ability to interact with DNA, RNA and proteins. In this review, we mainly focus on how lncRNAs affect cancer metastasis by modulating expression of key metastasis-associated genes at various levels of gene regulation. We also discuss how lncRNAs confer cancer cells either sensitivity or resistance to various chemo-therapeutic drugs via different mechanisms. Finally, we highlight the immense potential of lncRNAs as prognostic and diagnostic biomarkers as well as therapeutic targets in cancer.

Formononetin relieves the facilitating effect of lncRNA AFAP1-AS1-miR-195/miR-545 axis on progression and chemo-resistance of triple-negative breast cancer

This investigation attempted to discern whether formononetin restrained progression of triple-negative breast cancer (TNBC) by blocking lncRNA AFAP1-AS1-miR-195/miR-545 axis. We prepared TNBC cell lines (i.e. MDA-MB-231 and BT-549) and normal human mammary epithelial cell line (i.e. MCF-10A) in advance, and the TNBC cell lines were, respectively, transfected by pcDNA3.1-lncRNA AFAP1-AS1, si-lncRNA AFAP1-AS1, pcDNA6.2/GW/EmGFP-miR-545 or pcDNA6.2/GW/EmGFP-miR-195. Resistance of TNBC cells in response to 5-Fu, adriamycin, paclitaxel and cisplatin was evaluated through MTT assay, while potentials of TNBC cells in proliferation, migration and invasion were assessed via CCK8 assay and Transwell assay. Consequently, silencing of lncRNA AFAP1-AS1 impaired chemo-resistance, proliferation, migration and invasion of TNBC cells (P<0.05), and over-expression of miR-195 and miR-545, which were sponged and down-regulated by lncRNA AFAP1-AS1 (P<0.05), significantly reversed the promoting effect of pcDNA3.1-lncRNA AFAP1-AS1 on proliferation, migration, invasion and chemo-resistance of TNBC cells (P<0.05). Furthermore, CDK4 and Raf-1, essential biomarkers of TNBC progression, were, respectively, subjected to target and down-regulation of miR-545 and miR-195 (P<0.05), and they were promoted by pcDNA3.1-lncRNA AFAP1-AS1 at protein and mRNA levels (P<0.05). Additionally, formononetin significantly decreased expressions of lncRNA AFAP1-AS1, CDK4 and Raf-1, while raised miR-195 and miR-545 expressions in TNBC cells (P<0.05), and exposure to it dramatically contained malignant behaviors of TNBC cells (P<0.05). In conclusion, formononetin alleviated TNBC malignancy by suppressing lncRNA AFAP1-AS1-miR-195/miR-545 axis, suggesting that molecular targets combined with traditional Chinese medicine could yield significant clinical benefits in TNBC.

Pan-cancer analysis reveals an immunological role and prognostic potential of PXN in human cancer

Paxillin (PXN) is a protein involved in numerous physiological processes, and its presence is closely related to the occurrence and development of many types of tumors. However, no studies have analyzed PXN from a pan-cancer perspective. We analyzed PXN expression, immune cell infiltration, prognosis, and biological function across different types of tumors included in The Cancer Genome Atlas and Gene Expression Omnibus datasets. The results showed that expression of PXN varies in different tumors. Expression of PXN strongly correlated with prognosis in patients with tumors; higher PXN expression usually was linked to poor overall and disease-free survival. Expression of PXN in breast invasive carcinoma and lymphoid neoplasm diffuse large B-cell lymphoma was related to the degree of CD8+ T-cell infiltration, and infiltration of cancer-associated fibroblasts, such as kidney renal papillary cell carcinoma and brain lower-grade glioma, was also observed in other tumors. The results of pan-cancer analysis showed that abnormal PXN expression was related to poor prognosis, immune infiltration, and protein phosphorylation in different tumor types. Therefore, the PXN gene may become a potential biomarker of clinical tumor prognosis.

Epigenetic Alterations in Triple-Negative Breast Cancer-The Critical Role of Extracellular Matrix

Triple-negative breast cancer (TNBC) is an aggressive subgroup of breast cancer characterized by genomic complexity and therapeutic options limited to only standard chemotherapy. Although it has been suggested that stratifying TNBC patients by pathway-specific molecular alterations may predict benefit from specific therapeutic agents, application in routine clinical practice has not yet been established. There is a growing body of the literature supporting that epigenetic modifications comprised by DNA methylation, chromatin remodeling and non-coding RNAs play a fundamental role in TNBC pathogenesis. Extracellular matrix (ECM) is a highly dynamic 3D network of macromolecules with structural and cellular regulatory roles. Alterations in the expression of ECM components result in uncontrolled matrix remodeling, thus affecting its ability to regulate vital functions of cancer cells, including proliferation, migration, adhesion, invasion and epithelial-to-mesenchymal transition (EMT). Recent molecular data highlight the major role of tumor microenvironment and ECM alterations in TNBC and approaches for targeting tumor microenvironment have recently been recognized as potential therapeutic strategies. Notably, many of the ECM/EMT modifications in cancer are largely driven by epigenetic events, highlighting the pleiotropic effects of the epigenetic network in TNBC. This article presents and critically discusses the current knowledge on the epigenetic alterations correlated with TNBC pathogenesis, with emphasis on those associated with ECM/EMT modifications, their prognostic and predictive value and their use as therapeutic targets.

LINC00665 Stimulates Breast Cancer Progression via Regulating miR-551b-5p

Introduction

Long intergenic non-protein coding RNA 665 (LINC00665) has been revealed to contribute cancer progression in many cancer types including liver and gastric cancer. However, the roles of LINC00665 in breast cancer (BC) remain to be explored.

Methods

We explored LINC00665 expression in BC tissues and normal tissues at GEPIA. Then, its expression in BC cells (HCC-1937, MDA-MB-231, and MCF-7) and normal cells (MCF10A) was analyzed with qRT-PCR. In addition, the mechanisms of LINC00665 in BC were explored using bioinformatic analyses, luciferase activity reporter assay, RNA pull-down assay, and rescue experiments.

Results

We showed LINC00665 expression was significantly increased in both BC tissues and cells. The knockdown of LINC00625 significantly inhibits BC cell growth and promotes cell apoptosis in vitro, while the overexpression of LINC00625 has the opposite effects on BC progression. LINC00665 could affect BC progression via regulating miR-551b-5p.

Discussion

Taken together, our study showed that the LINC00665/miR-551b-5p axis was involved in the progression of BC.

The Biological Roles of Exosomal Long Non-Coding RNAs in Cancers

Although it has many treatment strategies, cancer is still one of the most common causes of morbidity and mortality in the world. Exosomes are small extracellular vesicles (EVs) that can be secreted by almost all cells. Exosomes can encapsulate various types of molecules, including lipids, proteins, DNA, messenger RNAs, and non-coding RNAs [microRNAs (miRNAs) and long non-coding RNAs (lncRNAs)]. Exosome release is a way of communication between cells. They act as powerful signaling molecules between cancer cells and the surrounding cells that make up the cancer microenvironment. lncRNAs are a class of non-coding P, with a length of more than 200 bp, which are differentially expressed in many cancers. lncRNAs have been widely regarded as a new medium for cancer behavior. The presence of lncRNAs in circulation can be acellular or encapsulated in exosomal bodies released by cancer cells. Exosomal lncRNAs are functional and can transmit different phenotypic patterns to neighboring cells. Here, we reviewed the molecular mechanism of exosomal lncRNAs in regulating cancer progression, angiogenesis, and chemotherapy resistance, as well as the prospective applications of exosomal lncRNAs in cancer diagnosis, treatment and prognosis. These findings potentially promote the current understanding of exosomal lncRNAs and provide a new research direction for exosomal lncRNAs in cancer prevention, diagnosis, and treatment.

Promising long noncoding RNA DLX6-AS1 in malignant tumors

Although its diagnosis and treatment have greatly improved in recent decades, cancer remains the major cause of death worldwide. Thus, there is an urgent need to find novel biomarkers and therapeutic targets to improve efficiency of diagnosis and treatment of patients with cancer. Long noncoding RNAs (lncRNAs), a new class of noncoding RNAs (ncRNAs), have been found to play a salient role in human tumorigenesis and progression. Distal-less homeobox 6 antisense RNA 1 (DLX6-AS1) is a novel lncRNA with aberrant expression in various cancers tissues and cell lines compared with nontumor tissues and normal cell lines. Importantly, DLX6-AS1 is closely associated with tumor cell proliferation, apoptosis, invasion, and migration. Patients with high DLX6-AS1 expression often had poorer prognosis than those with low expression. The oncogenicity of DLX6-AS1 mainly (indirectly or indirectly) interacts with targeting genes, and then regulates downstream genes and signaling pathways. Together with the findings of animal model studies, these data suggest that DLX6-AS1 may serve as a feasible predictor or therapeutic target in different cancers. Herein, we summarize the main findings concerning the function and molecular mechanisms of DLX6-AS1 to identify a molecular basis for future clinical application.

Regulation of Oncogenic Targets by the Tumor-Suppressive miR-139 Duplex (miR-139-5p and miR-139-3p) in Renal Cell Carcinoma

We previously found that both the guide and passenger strands of the miR-139 duplex (miR-139-5p and miR-139-3p, respectively) were downregulated in cancer tissues. Analysis of TCGA datasets revealed that low expression of miR-139-5p (p < 0.0001) and miR-139-3p (p < 0.0001) was closely associated with 5-year survival rates of patients with renal cell carcinoma (RCC). Ectopic expression assays showed that miR-139-5p and miR-139-3p acted as tumor-suppressive miRNAs in RCC cells. Here, 19 and 22 genes were identified as putative targets of miR-139-5p and miR-139-3p in RCC cells, respectively. Among these genes, high expression of PLXDC1, TET3, PXN, ARHGEF19, ELK1, DCBLD1, IKBKB, and CSF1 significantly predicted shorter survival in RCC patients according to TCGA analyses (p < 0.05). Importantly, the expression levels of four of these genes, PXN, ARHGEF19, ELK1, and IKBKB, were independent prognostic factors for patient survival (p < 0.05). We focused on PXN (paxillin) and investigated its potential oncogenic role in RCC cells. PXN knockdown significantly inhibited cancer cell migration and invasion, possibly by regulating epithelial-mesenchymal transition. Involvement of the miR-139-3p passenger strand in RCC molecular pathogenesis is a new concept. Analyses of tumor-suppressive-miRNA-mediated molecular networks provide important insights into the molecular pathogenesis of RCC.