PVT1-derived miR-1207-5p promotes breast cancer cell growth by targeting STAT6

Mapping the function of MicroRNAs as a critical regulator of tumor-immune cell communication in breast cancer and potential treatment strategies

Among women, breast cancer ranks as the most prevalent form of cancer, and the presence of metastases significantly reduces prognosis and diminishes overall survival rates. Gaining insights into the biological mechanisms governing the conversion of cancer cells, their subsequent spread to other areas of the body, and the immune system's monitoring of tumor growth will contribute to the advancement of more efficient and targeted therapies. MicroRNAs (miRNAs) play a critical role in the interaction between tumor cells and immune cells, facilitating tumor cells' evasion of the immune system and promoting cancer progression. Additionally, miRNAs also influence metastasis formation, including the establishment of metastatic sites and the transformation of tumor cells into migratory phenotypes. Specifically, dysregulated expression of these genes has been associated with abnormal expression of oncogenes and tumor suppressor genes, thereby facilitating tumor development. This study aims to provide a concise overview of the significance and function of miRNAs in breast cancer, focusing on their involvement as tumor suppressors in the antitumor immune response and as oncogenes in metastasis formation. Furthermore, miRNAs hold tremendous potential as targets for gene therapy due to their ability to modulate specific pathways that can either promote or suppress carcinogenesis. This perspective highlights the latest strategies developed for miRNA-based therapies.

Routine molecular applications and recent advances in breast cancer diagnostics

Cancer stands as one of the most common and lethal diseases, imposing a substantial burden on global mortality rates. Breast cancer is distinct from other forms of cancer in which it is the primary cause of death for women. Early detection of breast cancer can significantly lower the risk of mortality, improving the prognosis for those who are affected. The death rate of breast cancer has been steadily rising, according to epidemiological data, especially since the COVID-19 pandemic. This emphasizes the necessity of sensitive and precise technologies that can be utilized in early breast cancer diagnosis. In this process, biomarkers play a pivotal role by facilitating the early detection and diagnosis of breast cancer. Currently, a wide variety of cancer biomarkers have been identified, improving the accuracy of cancer diagnosis. These biomarkers can be applied in liquid biopsies as well as on solid tissues. In the context of breast cancer, biomarkers are particularly valuable for determining who is predisposed to the disease, predicting prognosis at the time of diagnosis, and selecting the best course of therapy. This review comprehensively explores the recently developed gene-based biomarkers from biofluids that are used in the context of breast cancer, as well as the conventional and cutting-edge techniques that have been employed for breast cancer diagnosis.

Impact of MICA 3'UTR allelic variability on miRNA binding prediction, a bioinformatic approach

MicroRNAs (miRNAs) are small non-coding RNAs that participate as powerful genetic regulators. MiRNAs can interfere with cellular processes by interacting with a broad spectrum of target genes under physiological and pathological states, including cancer development and progression. Major histocompatibility complex major histocompatibility complex class I-related chain A (MICA) belongs to a family of proteins that bind the natural-killer group 2, member D (NKG2D) receptor on Natural Killer cells and other cytotoxic lymphocytes. MICA plays a crucial role in the host's innate immune response to several disease settings, including cancer. MICA harbors various single nucleotide polymorphisms (SNPs) located in its 3'-untranslated region (3'UTR), a characteristic that increases the complexity of MICA regulation, favoring its post-transcriptional modulation by miRNAs under physiological and pathological conditions. Here, we conducted an in-depth analysis of MICA 3'UTR sequences according to each MICA allele described to date using NCBI database. We also systematically evaluated interactions between miRNAs and their putative targets on MICA 3'UTR containing SNPs using in silico analysis. Our in silico results showed that MICA SNPs rs9266829, rs 1880, and rs9266825, located in the target sequence of miRNAs hsa-miR-106a-5p, hsa-miR-17-5p, hsa-miR-20a-5p, hsa-miR-20b-5p, hsa-miR-93, hsa-miR-1207.5p, and hsa-miR-711 could modify the binding free energy between -8.62 and -18.14 kcal/mol, which may affect the regulation of MICA expression. We believe that our results may provide a starting point for further exploration of miRNA regulatory effects depending on MICA allelic variability; they may also be a guide to conduct miRNA in silico analysis for other highly polymorphic genes.

Biological Implications of MicroRNAs as Regulators and Biomarkers of Therapeutic Toxicities in Breast Cancer

Contemporary breast cancer management includes surgical resection combined with a multimodal approach, including chemotherapy, radiotherapy, endocrine therapy, and targeted therapies. Breast cancer treatment is now personalised in accordance with disease and host factors, which has translated to enhanced outcomes for the vast majority of patients. Unfortunately, the treatment of the disease involves patients developing treatment-induced toxicities, with cardiovascular and metabolic side effects having negative implications for long-term quality-of-life metrics. MicroRNAs (miRNAs) are a class of small non-coding ribonucleic acids that are 17 to 25 nucleotides in length, which have utility in modifying genetic expression by working at a post-transcriptional cellular level. miRNAs have involvement in modulating breast cancer development, which is well described, with these biomarkers acting as important regulators of disease, as well as potential diagnostic and therapeutic biomarkers. This review focuses on highlighting the role of miRNAs as regulators and biomarkers of disease, particularly in breast cancer management, with a specific mention of the potential value of miRNAs in predicting treatment-related cardiovascular toxicity.

LncRNA PVT1: as a therapeutic target for breast cancer

A significant number of women are identified with breast cancer (BC) every year, making it among the most prevalent malignancies and one of the leading causes of mortality globally. Despite significant progress in understanding BC pathogenesis and treatment options, there is still a need to identify new therapeutic targets and develop more effective treatments. LncRNAs have been discovered as biomarkers and a promising target for various cancers, including BC. PVT1 is a particular one of these lncRNAs, and research has indicated that it has a significant impact on the appearance and progression of BC.PVT1 is an attractive therapeutic target for BC due to its role in promoting cancer cell growth, metastasis and invasion. In addition to its potential as a treatment strategy, PVT1 may also have diagnostic value in BC. In this article, we will discuss targeting PVT1 as a treatment strategy for BC.

17β-estradiol suppresses H2O2-induced senescence in human umbilical vein endothelial cells by inducing autophagy through the PVT1/miR-31/SIRT3 axis

OBJECTIVE

17β-estradiol (17β-E₂) has been implicated in activating autophagy by upregulating SIRT3 (Sirtuin 3) expression, thereby inhibiting the senescence of vascular endothelial cells. Herein, we further examined the molecular mechanisms that regulate SIRT3 expression in 17β-E₂-induced autophagy.

METHODS

Reverse-transcription-polymerase chain reaction was employed to measure the expression of plasmacytoma variant translocation 1 (PVT1), microRNAs (miRNAs), and SIRT3, and the dual-luciferase assay was used to determine their interaction. Electron microscopy observes autophagosomes, green fluorescent protein-microtubule-associated protein 1 light chain 3 (GFP-LC3) staining, and immunoblot analysis with antibodies against LC3，beclin-1, and P62 were conducted to measure autophagy. Cellular senescence was determined using immunoblot analysis with anti-phosphorylated retinoblastoma and senescence-associated β-galactosidase staining.

RESULTS

Women with higher estrogen levels (during the 10-13th day of the menstrual cycle or premenopausal) exhibit markedly higher serum levels of PVT1 than women with lower estrogen levels (during the menstrual period or postmenopausal). The dual-luciferase assay showed that PVT1 acts as a sponge for miR-31, and miR-31 binds to its target gene, SIRT3. The 17β-E₂ treatment increased the expression of PVT1 and SIRT3 and downregulated miR-31 expression in human umbilical vein endothelial cells (HUVECs). Consistently, PVT1 overexpression suppresses miR-31 expression, promotes 17β-E2-induced autophagy, and inhibits H₂O₂-induced senescence. miR-31 inhibitor increases SIRT3 expression and leads to activation of 17β-E₂-induced autophagy and suppression of H₂O₂-induced senescence.

CONCLUSION

Our findings demonstrated that 17β-E₂ upregulates PVT1 gene expression and PVT1 functions as a sponge to inhibit miR-31, resulting in the upregulation of SIRT3 expression and activation of autophagy and subsequent inhibition of H₂O₂-induced senescence in HUVECs.

Mechanisms of Long Non-Coding RNA in Breast Cancer

The landscape of pervasive transcription in eukaryotic genomes has made space for the identification of thousands of transcripts that are difficult to frame in a specific functional category. A new class has been broadly named as long non-coding RNAs (lncRNAs) and shortly defined as transcripts that are longer than 200 nucleotides with no or limited coding potential. So far, about 19,000 lncRNAs genes have been annotated in the human genome (Gencode 41), nearly matching the number of protein-coding genes. A key scientific priority is the functional characterization of lncRNAs, a major challenge in molecular biology that has encouraged many high-throughput efforts. LncRNA studies have been stimulated by the enormous clinical potential that these molecules promise and have been based on the characterization of their expression and functional mechanisms. In this review, we illustrate some of these mechanisms as they have been pictured in the context of breast cancer.

Upregulation of the c-MYC oncogene and adjacent long noncoding RNAs PVT1 and CCAT1 in esophageal squamous cell carcinoma

BACKGROUND

All cell types express long non-coding RNAs (lncRNAs), which have the potential to play a role in carcinogenesis by altering the levels of their expression. Squamous cell carcinoma of the esophagus (ESCC) is a deadly disease with a poor prognosis and a high frequency of lymphatic metastases. Understanding the functional role and signaling pathways of two neighboring lncRNAs, CCAT1 and PVT1, in this oncogene's pathogenesis may help us determine ESCC. Furthermore, it is still unclear whether these lncRNAs are linked to the clinicopathological characteristics of patients with ESCC.

METHODS

For this study, we used biopsy from the Imam Khomeini Cancer Institute's tumor bank in Tehran, Iran to obtain 40 ESCC tumor samples and their normal margin counterparts. The expression levels of the CCAT1, PVT1, and c-MYC genes were assessed using quantitative Real-Time RT-PCR. Additionally, demographic data and clinical-pathologic characteristics, such as tumor grade, tumor stage, lymph node, and metastasis, were taken into consideration. Graphpad prism version 8 was used for bioinformatics analyses.

RESULTS

Comparing ESCC tissues to non-tumor tissues, we found significant upregulation of PVT1, CCAT1, and c-MYC. Patients with ESCC who had increased PVT1 expression also had higher rates of advanced stage and lymph node metastasis, whereas increased CCAT1 expression was only linked to advanced stage and wasn't associated with lymph node metastasis. In predicting ESCC, CCAT1 (p < 0.05) was found to be an important factor. Overall survival was reduced by c-MYC and PVT1 overexpression (p < 0.001), according to Kaplan-Meier analysis. PVT1, CCAT1, and c-MYC were found to interact with 23 miRNAs with high and medium score classes, as shown in a bioinformatics study. We summarized the experimentally proven interactions between c-MYC, PVT1, and CCAT1 and other miRNAs, lncRNAs, and proteins.

CONCLUSION

This is the first report that CCAT1, PVT1 and c-MYC have been found to be up-regulated simultaneously in ESCC. It is possible that these genes may be involved in ESCC as a result of these findings. Therefore, as consequence, more research is needed to determine whether or not these lncRNAs play an oncogenic role in ESCC development and progression, as well as the regulatory mechanisms that control them.

Cell cycle related long non-coding RNAs as the critical regulators of breast cancer progression and metastasis

Cell cycle is one of the main cellular mechanisms involved in tumor progression. Almost all of the active molecular pathways in tumor cells directly or indirectly target the cell cycle progression. Therefore, it is necessary to assess the molecular mechanisms involved in cell cycle regulation in tumor cells. Since, early diagnosis has pivotal role in better cancer management and treatment, it is required to introduce the non-invasive diagnostic markers. Long non-coding RNAs (LncRNAs) have higher stability in body fluids in comparison with mRNAs. Therefore, they can be used as efficient non-invasive markers for the early detection of breast cancer (BCa). In the present review we have summarized all of the reported lncRNAs involved in cell cycle regulation in BCa. It has been reported that lncRNAs mainly affect the cell cycle in G1/S transition through the CCND1/CDK4-6 complex. Present review paves the way of introducing the cell cycle related lncRNAs as efficient markers for the early detection of BCa.

MiRNAs Overexpression and Their Role in Breast Cancer: Implications for Cancer Therapeutics

MicroRNAs have a plethora of roles in various biological processes in the cells and most human cancers have been shown to be associated with dysregulation of the expression of miRNA genes. MiRNA biogenesis involves two alternative pathways, the canonical pathway which requires the successful cooperation of various proteins forming the miRNA-inducing silencing complex (miRISC), and the non-canonical pathway, such as the mirtrons, simtrons, or agotrons pathway, which bypasses and deviates from specific steps in the canonical pathway. Mature miRNAs are secreted from cells and circulated in the body bound to argonaute 2 (AGO2) and miRISC or transported in vesicles. These miRNAs may regulate their downstream target genes via positive or negative regulation through different molecular mechanisms. This review focuses on the role and mechanisms of miRNAs in different stages of breast cancer progression, including breast cancer stem cell formation, breast cancer initiation, invasion, and metastasis as well as angiogenesis. The design, chemical modifications, and therapeutic applications of synthetic anti-sense miRNA oligonucleotides and RNA mimics are also discussed in detail. The strategies for systemic delivery and local targeted delivery of the antisense miRNAs encompass the use of polymeric and liposomal nanoparticles, inorganic nanoparticles, extracellular vesicles, as well as viral vectors and viruslike particles (VLPs). Although several miRNAs have been identified as good candidates for the design of antisense and other synthetic modified oligonucleotides in targeting breast cancer, further efforts are still needed to study the most optimal delivery method in order to drive the research beyond preclinical studies.

STAT family of transcription factors in breast cancer: Pathogenesis and therapeutic opportunities and challenges

Breast cancer is the most commonly diagnosed cancer and second-leading cause of cancer deaths in women. Breast cancer stem cells (BCSCs) promote metastasis and therapeutic resistance contributing to tumor relapse. Through activating genes important for BCSCs, transcription factors contribute to breast cancer metastasis and therapeutic resistance, including the signal transducer and activator of transcription (STAT) family of transcription factors. The STAT family consists of six major isoforms, STAT1, STAT2, STAT3, STAT4, STAT5, and STAT6. Canonical STAT signaling is activated by the binding of an extracellular ligand to a cell-surface receptor followed by STAT phosphorylation, leading to STAT nuclear translocation and transactivation of target genes. It is important to note that STAT transcription factors exhibit diverse effects in breast cancer; some are either pro- or anti-tumorigenic while others maintain dual, context-dependent roles. Among the STAT transcription factors, STAT3 is the most widely studied STAT protein in breast cancer for its critical roles in promoting BCSCs, breast cancer cell proliferation, invasion, angiogenesis, metastasis, and immune evasion. Consequently, there have been substantial efforts in developing cancer therapeutics to target breast cancer with dysregulated STAT3 signaling. In this comprehensive review, we will summarize the diverse roles that each STAT family member plays in breast cancer pathobiology, as well as, the opportunities and challenges in pharmacologically targeting STAT proteins and their upstream activators in the context of breast cancer treatment.

lncRNA PVT1: a novel oncogene in multiple cancers

Long noncoding RNAs are involved in epigenetic gene modification, including binding to the chromatin rearrangement complex in pre-transcriptional regulation and to gene promoters in gene expression regulation, as well as acting as microRNA sponges to control messenger RNA levels in post-transcriptional regulation. An increasing number of studies have found that long noncoding RNA plasmacytoma variant translocation 1 (PVT1) plays an important role in cancer development. In this review of a large number of studies on PVT1, we found that PVT1 is closely related to tumor onset, proliferation, invasion, epithelial–mesenchymal transformation, and apoptosis, as well as poor prognosis and radiotherapy and chemotherapy resistance in some cancers. This review comprehensively describes PVT1 expression in various cancers and presents novel approaches to the diagnosis and treatment of cancer.

LncRNA PVT1 Regulates miR-1207-5p to Affect Colon Cancer Proliferation and Migration via the Wnt6/β-catenin2 Pathway

Background: We aimed to evaluate the effects of lncRNA PTV1 on colon cancer proliferation and migration via the Wnt6/β-catenin2 pathway. Materials and Methods: A total of 117 colon cancer and normal adjacent tissue samples were collected. LncRNA PVT1 and miR-1207-5p expressions in these samples and colon cancer cell lines were detected by Quantitative reverse transcription-polymerase chain reaction (qRT-PCR). LncRNA PVT1-silencing cells and miR-1207-5p-overexpressing Caco-2-siPVT1 cells were constructed, respectively. The effects of lncRNA PVT1 silencing on cell proliferation were assessed by MTT and colony formation assays. The effects on invasion and migration were tested by Transwell and scratch assays respectively. The targeting regulatory relationship between miR-1207-5p and Wnt6 was analyzed by a dual-luciferase reporter assay. The relationship between lncRNA PVT1 and miR-1207-5p was studied by RNA-binding protein immunoprecipitation and RNA pull-down assays. The expressions of proteins in the Wnt6/β-catenin2 pathway were detected by Western blotting. Results: The lncRNA PVT1 mRNA expression in colon cancer tissue was significantly higher than that in normal adjacent tissue (p < 0.05). The expression in lncRNA PVT1-silencing cells was significantly down-regulated (p < 0.05). The colonies of Caco-2-siPVT1 cells decreased, accompanied by a reduced number of cells penetrating Matrigel and migration (p < 0.05). Compared with siPVT1 + NC group, the number of colonies and migration of siPVT1 + miR-1207-5p-overexpressing group increased significantly (p < 0.05). There was a targeting relationship between miR-1207-5p and PVT1. MiR-1207-5p had a targeted binding site with Wnt6. The protein expressions of Wnt6/β-catenin2 in Caco-2-siPVT1 group were significantly lower than those of control and Caco-2-siNC groups (p < 0.05). Conclusion: LncRNA PVT1 was highly expressed in colon cancer. It may enhance the proliferation and migration of colon cancer cells by up-regulating miR-1207-5p level and enhancing the Wnt6/β-catenin2 pathway.

Molecular and cellular functions of long non-coding RNAs in prostate and breast cancer

Long noncoding RNAs (lncRNAs) are defined as noncoding RNA transcripts with a length greater than 200 nucleotides. Research over the last decade has made great strides in our understanding of lncRNAs, especially in the biology of their role in cancer. In this article, we will briefly discuss the biogenesis and characteristics of lncRNAs, then review their molecular and cellular functions in cancer by using prostate and breast cancer as examples. LncRNAs are abundant, diverse, and evolutionarily, less conserved than protein-coding genes. They are often expressed in a tumor and cell-specific manner. As a key epigenetic factor, lncRNAs can use a wide variety of molecular mechanisms to regulate gene expression at each step of the genetic information flow pathway. LncRNAs display widespread effects on cell behavior, tumor growth, and metastasis. They act intracellularly and extracellularly in an autocrine, paracrine and endocrine fashion. Increased understanding of lncRNA's role in cancer has facilitated the development of novel biomarkers for cancer diagnosis, led to greater understanding of cancer prognosis, enabled better prediction of therapeutic responses, and promoted identification of potential targets for cancer therapy.

Long non-coding RNA PVT1 facilitates cell migration and invasion by regulating miR-148a-3p and ROCK1 in breast cancer

PURPOSE

Breast cancer (BC) is one of the most common malignant tumors for women. The role and potential mechanisms of long non-coding RNA plasmacytoma variant translocation 1 (lncRNA PVT1) were explored in BC cell migration and invasion.

METHODS

PVT1, miR-148a-3p and Rho‑associated, coiled‑coil containing protein kinase 1 (ROCK1) mRNA expressions were detected using real-time fluorescent quantitative polymerase chain reaction (qRT-PCR). The ROCK1 protein expression was detected by Western blotting. The relationship of PVT1, miR-148a-3p and ROCK1 was analyzed by Dual Luciferase activity, RNA immunoprecipitation (RIP) and Spearman correlation analysis. Cell invasion and migration were detected by Transwell assay.

RESULTS

Upregulation of PVT1 and ROCK1, and downregulation of miR-148a-3p were observed in BC tissues and cell lines. According to the analysis of Dual Luciferase activity, RIP and Spearman correlation analysis, miR-148a-3p directly binds to PVT1, and ROCK1 is a target of miR-148a-3p. In addition, PVT1 regulated the cells migration and invasion by regulating miR-148a-3p and ROCK1 expression.

CONCLUSION

These data demonstrated that PVT1 was upregulated and facilitated to the cell migration and invasion of BC by the regulation of miR-148a-3p and ROCK1, indicating that PVT1 may be a potential biomarker of BC diagnosis and treatment.

Identification and Validation of an Immune-Related lncRNA Signature to Facilitate Survival Prediction in Gastric Cancer

Background

Long noncoding RNAs (lncRNAs) are versatile in functions and can regulate cancer development, including the modulation of cancer immunity. Immune-related lncRNA signatures predicting prognosis have been reported in multiple cancers, but relevant studies in gastric cancer (GC) are still lacking.

Methods

We performed a comprehensive analysis using TCGA and Immport databases and identified an immune-related lncRNA signature by univariate and multivariate Cox regression analysis. qRT-PCR and immunohistochemistry assays were used for further validation. KEGG and GO analysis and ceRNA network establishment were carried out to explore the regulatory functions.

Results

We first identified an immune-related lncRNA signature, which can stratify gastric cancer patients into high- and low-risk subgroups and the high-risk cases frequently suffered from shorter overall survival time. Next, we validated the reliability of the lncRNA signature in an independent 75 gastric cancer samples and demonstrated that the three-year survival rate in high-risk patients was only 30.8% versus 66.5% in low-risk counterparts. Functional exploration indicated that the lncRNA signature might participate in multiple cancer-associated processes including cell adhesion and migration, cytokine-receptor interaction and immune evasion. Additionally, we observed that high-risk samples tended to form an immunosuppressive microenvironment, which had more M2-polarized macrophages and Tregs, but fewer CD8 effector T cells within tumors. Moreover, we found that PD-1 and PD-L1 were dramatically upregulated in a subset of high-risk patients with abundant M2 and Treg infiltration, implying these patients may benefit from anti-PD-1 and PD-L1 immunotherapy.

Conclusions

These results showed that the immune-related lncRNA signature had a prominent capacity to predict overall survival and the immune status of microenvironment in gastric cancer. Our findings may be useful for the risk-stratification management and provide a valuable clue to identify proper patients potentially benefit from immune checkpoint therapy in gastric cancer.

miR-1207-5p suppresses laryngeal squamous cell carcinoma progression by downregulating SKA3 and inhibiting epithelial-mesenchymal transition

Laryngeal squamous cell carcinoma (LSCC) is the second most common head and neck cancer. Previously, we discovered that miR-1207-5p was downregulated in LSCC. In this study, the clinical significance, function, and mechanism of miR-1207-5p in LSCC were investigated. Downregulation of miR-1207-5p was found to be strongly linked to the malignant progression of LSCC. Functional studies revealed that miR-1207-5p upregulation suppressed LSCC cell proliferation, invasion, migration, and xenograft tumor growth. Bioinformatics analysis revealed that miR-1207-5p target genes were involved in cell cycle regulation, proliferation, adhesion, and the phosphatidylinositol 3-kinase (PI3K)/Akt pathway. Mechanistic studies revealed that miR-1207-5p interacts directly with the 3′ untranslated region of spindle and kinetochore associated complex subunit 3 (SKA3) and downregulates SKA3 expression. Furthermore, SKA3 was found to be overexpressed in LSCC, and its high expression was associated with tumor progression and a poor prognosis. Rescue experiments demonstrated that miR-1207-5p inhibited the malignant phenotypes of LSCC via SKA3. Furthermore, miR-1207-5p upregulation or knockdown of SKA3 inhibited the epithelial-mesenchymal transition (EMT). Collectively, miR-1207-5p inhibited LSCC malignant progression by downregulating SKA3 and preventing EMT. These findings provide new insights into the mechanism of LSCC progression, as well as new potential biomarkers and therapeutic targets for LSCC diagnosis and treatment.

Long Non-Coding RNAs as Potential Diagnostic and Prognostic Biomarkers in Breast Cancer: Progress and Prospects

Breast cancer is the most common malignancy among women worldwide, excluding non-melanoma skin cancer. It is now well understood that breast cancer is a heterogeneous entity that exhibits distinctive histological and biological features, treatment responses and prognostic patterns. Therefore, the identification of novel ideal diagnostic and prognostic biomarkers is of utmost importance. Long non-coding RNAs (lncRNAs) are commonly defined as transcripts longer than 200 nucleotides that lack coding potential. Extensive research has shown that lncRNAs are involved in multiple human cancers, including breast cancer. LncRNAs with dysregulated expression can act as oncogenes or tumor-suppressor genes to regulate malignant transformation processes, such as proliferation, invasion, migration and drug resistance. Intriguingly, the expression profiles of lncRNAs tend to be highly cell-type-specific, tissue-specific, disease-specific or developmental stage-specific, which makes them suitable biomarkers for breast cancer diagnosis and prognosis.

Exosomal lncRNA PVT1/VEGFA Axis Promotes Colon Cancer Metastasis and Stemness by Downregulation of Tumor Suppressor miR-152-3p

Background

Treating advanced colon cancer remains challenging in clinical settings because of the development of drug resistance and distant metastasis. Mechanisms underlying the metastasis of colon cancer are complex and unclear.

Methods

Computational analysis was performed to determine genes associated with the exosomal long noncoding (lncRNA) plasmacytoma variant translocation 1 (PVT1)/vascular endothelial growth factor A (VEGFA) axis in patients with colon cancer. The biological importance of the exosomal lncRNA PVT1/VEGFA axis was examined in vitro by using HCT116 and LoVo cell lines and in vivo by using a patient-derived xenograft (PDX) mouse model through knockdown (by silencing of PVT1) and overexpression (by adding serum exosomes isolated from patients with distant metastasis (M-exo)).

Results

The in silico analysis demonstrated that PVT1 overexpression was associated with poor prognosis and increased expression of metastatic markers such as VEGFA and epidermal growth factor receptor (EGFR). This finding was further validated in a small cohort of patients with colon cancer in whom increased PVT1 expression was correlated with colon cancer incidence, disease recurrence, and distant metastasis. M-exo were enriched with PVT1 and VEGFA, and both migratory and invasive abilities of colon cancer cell lines increased when they were cocultured with M-exo. The metastasis-promoting effect was accompanied by increased expression of Twist1, vimentin, and MMP2. M-exo promoted metastasis in PDX mice. In vitro silencing of PVT1 reduced colon tumorigenic properties including migratory, invasive, colony forming, and tumorsphere generation abilities. Further analysis revealed that PVT1, VEGFA, and EGFR interact with and are regulated by miR-152-3p. Increased miR-152-3p expression reduced tumorigenesis, where increased tumorigenesis was observed when miR-152-3p expression was downregulated.

Conclusion

Exosomal PVT1 promotes colon cancer metastasis through its association with EGFR and VEGFA expression. miR-152-3p targets both PVT1 and VEGFA, and this regulatory pathway can be explored for drug development and as a prognostic biomarker.

Identification and Roles of miR-29b-1-3p and miR29a-3p-Regulated and Non-Regulated lncRNAs in Endocrine-Sensitive and Resistant Breast Cancer Cells

Despite improvements in the treatment of endocrine-resistant metastatic disease using combination therapies in patients with estrogen receptor α (ERα) primary tumors, the mechanisms underlying endocrine resistance remain to be elucidated. Non-coding RNAs (ncRNAs), including microRNAs (miRNA) and long non-coding RNAs (lncRNA), are targets and regulators of cell signaling pathways and their exosomal transport may contribute to metastasis. Previous studies have shown that a low expression of miR-29a-3p and miR-29b-3p is associated with lower overall breast cancer survival before 150 mos. Transient, modest overexpression of miR-29b1-3p or miR-29a-3p inhibited MCF-7 tamoxifen-sensitive and LCC9 tamoxifen-resistant cell proliferation. Here, we identify miR-29b-1/a-regulated and non-regulated differentially expressed lncRNAs in MCF-7 and LCC9 cells using next-generation RNA seq. More lncRNAs were miR-29b-1/a-regulated in LCC9 cells than in MCF-7 cells, including DANCR, GAS5, DSCAM-AS1, SNHG5, and CRND. We examined the roles of miR-29-regulated and differentially expressed lncRNAs in endocrine-resistant breast cancer, including putative and proven targets and expression patterns in survival analysis using the KM Plotter and TCGA databases. This study provides new insights into lncRNAs in endocrine-resistant breast cancer.

Potential Therapeutic Effects of Melatonin Mediate via miRNAs in Cancer

miRNAs are evolutionarily conserved non-coding ribonucleic acids with a length of between 19 and 25 nucleotides. Because of their ability to regulate gene expression, miRNAs have an important function in the controlling of various biological processes, such as cell cycle, differentiation, proliferation, and apoptosis. Owing to the long-standing regulative potential of miRNAs in tumor-suppressive pathways, scholars have recently paid closer attention to the expression profile of miRNAs in various types of cancer. Melatonin, an indolic compound secreted from pineal gland and some peripheral tissues, has been considered as an effective anti-tumor hormone in a wide spectrum of cancers. Furthermore, it induces apoptosis, inhibits tumor metastasis and invasion, and also angiogenesis. A growing body of evidence indicates the effects of melatonin on miRNAs expression in broad spectrum of diseases, including cancer. Due to the long-term effects of the regulation of miRNAs expression, melatonin could be a promising therapeutic factor in the treatment of cancers via the regulation of miRNAs. Therefore, in this review, we will discuss the effects of melatonin on miRNAs expression in various types of cancers.

MicroRNA Regulation of Breast Cancer Stemness

Recent advances in our understanding of breast cancer have demonstrated that cancer stem-like cells (CSCs, also known as tumor-initiating cell (TICs)) are central for progression and recurrence. CSCs are a small subpopulation of cells present in breast tumors that contribute to growth, metastasis, therapy resistance, and recurrence, leading to poor clinical outcome. Data have shown that cancer cells can gain characteristics of CSCs, or stemness, through alterations in key signaling pathways. The dysregulation of miRNA expression and signaling have been well-documented in cancer, and recent studies have shown that miRNAs are associated with breast cancer initiation, progression, and recurrence through regulating CSC characteristics. More specifically, miRNAs directly target central signaling nodes within pathways that can drive the formation, maintenance, and even inhibition of the CSC population. This review aims to summarize these research findings specifically in the context of breast cancer. This review also discusses miRNAs as biomarkers and promising clinical therapeutics, and presents a comprehensive summary of currently validated targets involved in CSC-specific signaling pathways in breast cancer.

miRNA-independent function of long noncoding pri-miRNA loci

Among the large, diverse set of mammalian long noncoding RNAs (lncRNAs), long noncoding primary microRNAs (lnc-pri-miRNAs) are those that host miRNAs. Whether lnc-pri-miRNA loci have important biological function independent of their cognate miRNAs is poorly understood. From a genome-scale lncRNA screen, lnc-pri-miRNA loci were enriched for function in cell proliferation, and in glioblastoma (i.e., GBM) cells with DGCR8 or DROSHA knockdown, lnc-pri-miRNA screen hits still regulated cell growth. To molecularly dissect the function of a lnc-pri-miRNA locus, we studied LOC646329 (also known as MIR29HG), which hosts the miR-29a/b1 cluster. In GBM cells, LOC646329 knockdown reduced miR-29a/b1 levels, and these cells exhibited decreased growth. However, genetic deletion of the miR-29a/b1 cluster (LOC646329-miR29Δ) did not decrease cell growth, while knockdown of LOC646329-miR29Δ transcripts reduced cell proliferation. The miR-29a/b1-independent activity of LOC646329 corresponded to enhancer-like activation of a neighboring oncogene (MKLN1), regulating cell propagation. The LOC646329 locus interacts with the MKLN1 promoter, and antisense oligonucleotide knockdown of the lncRNA disrupts these interactions and reduces the enhancer-like activity. More broadly, analysis of genome-wide data from multiple human cell types showed that lnc-pri-miRNA loci are significantly enriched for DNA looping interactions with gene promoters as well as genomic and epigenetic characteristics of transcriptional enhancers. Functional studies of additional lnc-pri-miRNA loci demonstrated cognate miRNA-independent enhancer-like activity. Together, these data demonstrate that lnc-pri-miRNA loci can regulate cell biology via both miRNA-dependent and miRNA-independent mechanisms.

Targeting PVT1 Exon 9 Re-Expresses Claudin 4 Protein and Inhibits Migration by Claudin-Low Triple Negative Breast Cancer Cells

PVT1 is a long non-coding RNA transcribed from a gene located at the 8q24 chromosomal region that has been implicated in multiple cancers including breast cancer (BC). Amplification of the 8q24 chromosomal region is a common event in BC and is associated with poor clinical outcomes. Claudin-low (CL) triple negative breast cancer (TNBC) is a subtype of BC with a particularly dismal outcome. We assessed PVT1 exon 9 expression in the T47D estrogen receptor positive BC cell line, and in the MDA MB 468 and MDA MB 231 TNBC cell lines, followed by the assessment of the expression of claudins 1, 3, 4 and 7, in MDA MB 468 and MDA MB 231 (TNBC) cells. We found that MDA MB 231 TNBC cells significantly express less claudin 1, 3, 4, and 7 than MDA MB 468 TNBC cells. PVT1 exon 9 is significantly upregulated in MDA MB 231 CL TNBC cells, and significantly downregulated in MDA MB 468 claudin high (CH) TNBC cells, in comparison to T47D estrogen receptor positive BC cells. We then analyzed the functional consequences of siRNA targeting of PVT1 exon 9 expression in the MDA MB 231 CL TNBC cells. Notably, siRNA targeting of PVT1 exon 9 expression in the MDA MB 231 CL TNBC cells led to a significant reduction in migration and the re-expression of claudin 4. Taken together, our data indicate that PVT1 exon 9 regulates claudin 4 expression and migration in CL TNBC cells, and may have clinical implications in CL TNBC.

8q24.21 Locus: A Paradigm to Link Non-Coding RNAs, Genome Polymorphisms and Cancer

The majority of the human genome is comprised of non-protein-coding genes, but the relevance of non-coding RNAs in complex diseases has yet to be fully elucidated. One class of non-coding RNAs is long non-coding RNAs or lncRNAs, many of which have been identified to play a range of roles in transcription and translation. While the clinical importance of the majority of lncRNAs have yet to be identified, it is puzzling that a large number of disease-associated genetic variations are seen in lncRNA genes. The 8q24.21 locus is rich in lncRNAs and very few protein-coding genes are located in this region. Interestingly, the 8q24.21 region is also a hot spot for genetic variants associated with an increased risk of cancer. Research focusing on the lncRNAs in this area of the genome has indicated clinical relevance of lncRNAs in different cancers. In this review, we summarise the lncRNAs in the 8q24.21 region with respect to their role in cancer and discuss the potential impact of cancer-associated genetic polymorphisms on the function of lncRNAs in initiation and progression of cancer.

miR-301b-3p Regulates Breast Cancer Cell Proliferation, Migration, and Invasion by Targeting NR3C2

Objectives

Breast cancer is the most common malignant tumor among females, and miRNAs have been reported to play an important regulatory role in breast cancer progression. This study aimed to explore the function and underlying molecular mechanism of miR-301b-3p in breast cancer.

Methods

Differential analysis and survival analysis were performed based on the data accessed from the TCGA-BRCA dataset for identification of the target miRNA. Bioinformatics analysis was conducted to predict the downstream target gene of the miRNA. Real-time quantitative PCR was carried out to detect the expression of miR-301b-3p and nuclear receptor subfamily 3 group C member 2 (NR3C2). Western blot was used to assess the protein expression of NR3C2. Cell counting kit-8 assay was performed to evaluate the proliferation of breast cancer cells. Transwell assay was conducted to determine the migratory and invasive abilities of breast cancer cells. Dual-luciferase reporter assay was employed to verify the targeting relationship between miR-301b-3p and NR3C2.

Results

miR-301b-3p was elevated in breast cancer cell lines and promoted cell proliferation, migration, and invasion in terms of its biological function in breast cancer. NR3C2 was validated as a direct target of miR-301b-3p via bioinformatics analysis and dual-luciferase reporter assay, and NR3C2 was downregulated in breast cancer cell lines. The rescue experiment indicated that NR3C2 was involved in the mechanism by which miR-301b-3p regulated the malignant phenotype of breast cancer cells.

Conclusion

The present study revealed for the first time that miR-301b-3p could foster breast cancer cell proliferation, migration, and invasion by targeting NR3C2, unveiling that miR-301b-3p is a novel carcinogen in breast cancer.

GPER1 and microRNA: Two Players in Breast Cancer Progression

Breast cancer is the main cause of morbidity and mortality in women worldwide. However, the molecular pathogenesis of breast cancer remains poorly defined due to its heterogeneity. Several studies have reported that G Protein-Coupled Estrogen Receptor 1 (GPER1) plays a crucial role in breast cancer progression, by binding to estrogens or synthetic agonists, like G-1, thus modulating genes involved in diverse biological events, such as cell proliferation, migration, apoptosis, and metastasis. In addition, it has been established that the dysregulation of short sequences of non-coding RNA, named microRNAs (miRNAs), is involved in various pathophysiological conditions, including breast cancer. Recent evidence has indicated that estrogens may regulate miRNA expression and therefore modulate the levels of their target genes, not only through the classical estrogen receptors (ERs), but also activating GPER1 signalling, hence suggesting an alternative molecular pathway involved in breast tumor progression. Here, the current knowledge about GPER1 and miRNA action in breast cancer is recapitulated, reporting recent evidence on the liaison of these two players in triggering breast tumorogenic effects. Elucidating the role of GPER1 and miRNAs in breast cancer might provide new tools for innovative approaches in anti-cancer therapy.

LncRNA MIR194-2HG Promotes Cell Proliferation and Metastasis via Regulation of miR-1207-5p/TCF19/Wnt/β-Catenin Signaling in Liver Cancer

Purpose

LncRNAs play an important role in tumorigenesis and cancer progression in liver cancer. Although many lncRNAs have been reported, the role of MIR194-2HG and the underlying mechanism mediated by it are still largely unknown in HCC. This study aimed to investigate the biological role and mechanism of MIR194-2HG in liver cancer.

Materials and Methods

The expression of MIR194-2HG was determined in liver cancer tissues and cells by RT-qPCR. The overall survival rate of MIR194-2HG was analyzed by Kaplan–Meier survival analysis. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), colony formation, and Transwell assays were carried out to detect cell migration and invasion. Western blotting was used to quantify the levels of all proteins. The regulatory mechanism of the MIR194-2HG/miR-1207-5p/TCF19 axis in liver cancer was investigated by dual-luciferase activity reporter assay, Kaplan-Meier survival analysis, and Western blotting.

Results

MIR194-2HG was upregulated in liver cancer tissues and cell lines. Liver cancer patients with higher expression of MIR194-2HG revealed poor overall survival compared with those who had lower expression of MIR194-2HG. MIR194-2HG promoted the proliferation, migration, and invasion of HepG2 and Huh7 cells by acting as a ceRNA mechanism for the miR-1207-5p/TCF19 axis to activate the Wnt/β-catenin signaling pathway.

Conclusion

MIR194-2HG acts in an oncogenic role and activates the Wnt/β-catenin signaling pathway via a miR-1207-5p/TCF19 axis-mediated mechanism, which provides a novel avenue for diagnostic or therapeutic interventions in liver cancer.

Long noncoding RNA PVT1 promotes tumor cell proliferation, invasion, migration and inhibits apoptosis in oral squamous cell carcinoma by regulating miR‑150‑5p/GLUT‑1

Oral squamous cell carcinoma (OSCC) is a cancer with high morbidity and mortality. Research has demonstrated that long non-coding RNAs (lncRNAs) are critical for tumor initiation and development. In the present study, we aimed to ascertain the functions and potential mechanisms of lncRNA plasmacytoma variant translocation 1 (PVT1) in OSCC. Firstly, we found that the expression of PVT1 was increased in human OSCC tumor tissues and it was related to reduced survival of the patients. Furthermore, miR-150-5p expression was downregulated in OSCC tumor tissues and it was negatively related with PVT1. Moreover, GLUT-1 protein expression was upregulated in human OSCC tumor tissues. In addition, cell proliferation capacity was measured by CCK-8 assay and cell invasion and migration were measured by Transwell assay. PVT1 overexpression promoted cell proliferation, invasion and migration, while these effects were abrogated by PVT1 downregulation. In addition, luciferase gene reporter assay verified the miR-150-5p directly binds with PVT1, which regulates the biological functions of OSCC. Additionally, luciferase gene reporter assay confirmed that GLUT-1 was a target for miR-150-5p. The promotion of cell proliferation, invasion and migration in LV-PVT1-transfected cells was eliminated following miR-150-5p overexpression. Finally, in vivo nude mouse xenograft model further verified that PVT1 knockdown inhibited tumor growth, formation, invasion and migration. According to the results, PVT1 is increased in human OSCC tumor tissues, and is related to the poor prognosis of human OSCC patients. We uncovered a previously unappreciated PVT1/miR-150-5p/GLUT-1 signaling axis that promotes cell proliferation, invasion, migration and inhibits apoptosis in OSCC cell lines and in vivo, which suggests that this axis could be a target for the treatment of OSCC.

Dissecting miRNA facilitated physiology and function in human breast cancer for therapeutic intervention

MicroRNAs (miRNAs) are key epigenomic regulators of biological processes in animals and plants. These small non coding RNAs form a complex networks that regulate cellular function and development. MiRNAs prevent translation by either inactivation or inducing degradation of mRNA, a major concern in post-transcriptional gene regulation. Aberrant regulation of gene expression by miRNAs is frequently observed in cancer. Overexpression of various 'oncomiRs' and silencing of tumor suppressor miRNAs are associated with various types of human cancers, although overall downregulation of miRNA expression is reported as a hallmark of cancer. Modulations of the total pool of cellular miRNA by alteration in genetic and epigenetic factors associated with the biogenesis of miRNA machinery. It also depends on the availability of cellular miRNAs from its store in the organelles which affect tumor development and cancer progression. Here, we have dissected the roles and pathways of various miRNAs during normal cellular and molecular functions as well as during breast cancer progression. Recent research works and prevailing views implicate that there are two major types of miRNAs; (i) intracellular miRNAs and (ii) extracellular miRNAs. Concept, that the functions of intracellular miRNAs are driven by cellular organelles in mammalian cells. Extracellular miRNAs function in cell-cell communication in extracellular spaces and distance cells through circulation. A detailed understanding of organelle driven miRNA function and the precise role of extracellular miRNAs, pre- and post-therapeutic implications of miRNAs in this scenario would open several avenues for further understanding of miRNA function and can be better exploited for the treatment of breast cancers.

Non-Coding RNAs as Regulators and Markers for Targeting of Breast Cancer and Cancer Stem Cells

Breast cancer is regarded as a heterogeneous and complicated disease that remains the prime focus in the domain of public health concern. Next-generation sequencing technologies provided a new perspective dimension to non-coding RNAs, which were initially considered to be transcriptional noise or a product generated from erroneous transcription. Even though understanding of biological and molecular functions of noncoding RNA remains enigmatic, researchers have established the pivotal role of these RNAs in governing a plethora of biological phenomena that includes cancer-associated cellular processes such as proliferation, invasion, migration, apoptosis, and stemness. In addition to this, the transmission of microRNAs and long non-coding RNAs was identified as a source of communication to breast cancer cells either locally or systemically. The present review provides in-depth information with an aim at discovering the fundamental potential of non-coding RNAs, by providing knowledge of biogenesis and functional roles of micro RNA and long non-coding RNAs in breast cancer and breast cancer stem cells, as either oncogenic drivers or tumor suppressors. Furthermore, non-coding RNAs and their potential role as diagnostic and therapeutic moieties have also been summarized.

Oncogenic Role of PVT1 and Therapeutic Implications

PVT1, a long non-coding RNA has been implicated in a variety of human cancers. Recent advancements have led to increasing discovery of the critical roles of PVT1 in cancer initiation and progression. Novel insight is emerging about PVT1's mechanism of action in different cancers. Identifying and understanding the variety of activities of PVT1 involved in cancers is a necessity for the development of PVT1 as a diagnostic biomarker or therapeutic target in cancers where PVT1 is dysregulated. PVT1's varied activities include overexpression, modulation of miRNA expression, protein interactions, targeting of regulatory genes, formation of fusion genes, functioning as a competing endogenous RNA (ceRNA), and interactions with MYC, among many others. Furthermore, bioinformatic analysis of PVT1 interactions in cancers has aided understanding of the numerous pathways involved in PVT1 contribution to carcinogenesis in a cancer type-specific manner. However, these recent findings show that there is much more to be learned to be able to fully exploit PVT1 for cancer prognostication and therapy. In this review, we summarize some of the latest findings on PVT1's oncogenic activities, signaling networks and how targeting these networks can be a strategy for cancer therapy.

LncRNA MIR503HG Promotes High-Glucose-Induced Proximal Tubular Cell Apoptosis by Targeting miR-503-5p/Bcl-2 Pathway

AIM

More than half of microRNAs are located in genes. LncRNAs are host genes of intronic microRNAs that regulate intracellular splicing to form pre-miRNAs that are processed to mature miRNAs. MicroRNAs work as partners or antagonists of their host lncRNAs by fine-tuning their target genes. However, whether lncRNA-MIR503HG (miR-503 host gene) is co-transcribed with miR-503 and affects miR-503 splicing, thereby affecting its target gene Bcl-2 expression and cell mitochondrial apoptotic pathway in diabetic nephropathy (DN) is currently unknown.

METHODS

Human proximal tubular (HK-2) cells cultured in high glucose were transfected with lncRNA MIR503HG overexpression/inhibition plasmid and miR-503 mimics/inhibitor. Real-time quantitative PCR was used to measure the expression levels of lncRNA MIR503HG, pre-miR-503, miR-503 and Bcl-2. Western blot was used to measure the protein expressions of Bcl-2, Bax, Cytc and cleaved-caspase 9/3. Annexin V/PI flow cytometry was used to measure apoptosis.

RESULTS

Host lncRNA MIR503HG was co-transcribed with miR-503. MIR503HG regulated the expression of miR-503 by affecting miR-503 splicing synthesis. In the presence of high glucose, the expression levels of lncRNA MIR503HG and miR-503 were up-regulated in HK-2 cells cultured in high glucose. Bcl-2 expression was inhibited and levels of apoptosis-related proteins Cytc and Bax were increased in HK-2 cells cultured in high glucose, all of which promoted the caspase cascade reaction, leading to increased caspase-9 and caspase-3 shear fragments inducing apoptosis of the mitochondrial pathway. Inhibition of MIR503HG led to a reduction in miR-503 expression, up-regulated its target gene Bcl-2, inhibited the expression levels of Bax and other apoptosis-related proteins and attenuated HK-2 cell apoptosis induced by high glucose. Co-transfection of miRNA-503 partially offset the effect of MIR503HG-siRNA.

CONCLUSION

MIR503HG indirectly regulates Bcl-2 by promoting the co-transcription of miRNA-503 to participate high-glucose-induced proximal tubular cell apoptosis, providing a new target for diabetic nephropathy treatment.

Tanshinol inhibits growth of malignant melanoma cells via regulating miR-1207-5p/CHPF pathway

Tanshinol possesses anti-tumor activity in melanoma both in vitro and in vivo, and miR-1207-5p is involved in tumor progression in melanoma. However, whether miR-1207-5p can be affected by tanshinol treatment in melanoma is not clear. The expression levels of miR-1207-5p were detected by RT-qPCR. The validation of the direct target of miR-1207-5p was through dual-luciferase reporter assay and western blotting assay. The cell viability rate was determined using MTT assay and colony formation assay. The cell mobility was assessed using Transwell migration/invasion assay. Downregulation of miR-1207-5p was found in melanoma cell lines and tissues and was associated with tumor stages, presence of ulceration, lymph node metastasis, and poor overall survival rate of melanoma patients. Tanshinol treatment and miR-1207-5p overexpression suppressed melanoma cell growth and cell mobility. Chondroitin polymerizing factor (CHPF) is a direct target of miR-1207-5p. Tanshinol exerted anti-tumor activity to melanoma through the regulation of miR-1207-5p/CHPF signaling. Our study highlighted the potential therapeutic application of tanshinol and miR-1207-5p as a supplement to enhance the effect of the traditional cancer treatment methods against melanoma.

Long Non-coding RNA PVT1 as a Prognostic and Therapeutic Target in Pediatric Cancer

In recent decades, biomedical research has focused on understanding the functionality of the human translated genome, which represents a minor part of all genetic information transcribed from the human genome. However, researchers have become aware of the importance of non-coding RNA species that constitute the vast majority of the transcriptome. In addition to their crucial role in tissue development and homeostasis, mounting evidence shows non-coding RNA to be deregulated and functionally contributing to the development and progression of different types of human disease including cancer both in adults and children. Small non-coding RNAs (i.e., microRNA) are in the vanguard of clinical research which revealed that RNA could be used as disease biomarkers or new therapeutic targets. Furthermore, many more expectations have been raised for long non-coding RNAs, by far the largest fraction of non-coding transcripts, and still fewer findings have been translated into clinical applications. In this review, we center on PVT1, a large and complex long non-coding RNA that usually confers oncogenic properties on different tumor types. We focus on the compilation of early advances in the field of pediatric tumors which often lags behind clinical improvements in adult tumors, and provide a rationale to continue studying PVT1 as a possible functional contributor to pediatric malignancies and as a potential prognostic marker or therapeutic target.

The Regulatory Role of MicroRNAs in Breast Cancer

MicroRNAs (miRNAs) are small non-coding RNA molecules which function as critical post-transcriptional gene regulators of various biological functions. Generally, miRNAs negatively regulate gene expression by binding to their selective messenger RNAs (mRNAs), thereby leading to either mRNA degradation or translational repression, depending on the degree of complementarity with target mRNA sequences. Aberrant expression of these miRNAs has been linked etiologically with various human diseases including breast cancer. Different cellular pathways of breast cancer development such as cell proliferation, apoptotic response, metastasis, cancer recurrence and chemoresistance are regulated by either the oncogenic miRNA (oncomiR) or tumor suppressor miRNA (tsmiR). In this review, we highlight the current state of research into miRNA involved in breast cancer, with particular attention to articles published between the years 2000 to 2019, using detailed searches of the databases PubMed, Google Scholar, and Scopus. The post-transcriptional gene regulatory roles of various dysregulated miRNAs in breast cancer and their potential as therapeutic targets are also discussed.

Long noncoding RNA HAGLR acts as a microRNA-143-5p sponge to regulate epithelial-mesenchymal transition and metastatic potential in esophageal cancer by regulating LAMP3

Homeobox D gene cluster antisense growth-associated long noncoding RNA (HAGLR) functions as a crucial regulator in the progression and development of human cancers. We analyzed effects of HAGLR, microRNA (miR)-143-5p and lysosome-associated membrane glycoprotein (LAMP)3 on esophageal cancer (EC) and the related mechanisms. Microarray analysis was used to screen out EC-related genes and the regulation network among HAGLR, miR-143-5p, and LAMP3. The regulatory mechanisms of HAGLR and miR-143-5p in EC were analyzed following the treatment of miR-143-5p mimic, miR-143-5p inhibitor, HAGLR vector, or small interfering RNA against HAGLR in EC cells. The expression of N-cadherin, vimentin, Twist1, Snail1, and E-cadherin as well as the abilities of cell proliferation, invasion, and migration were measured. The effects of the HAGLR/miR-143-5p/LAMP3 axis were determined in vivo by assessing tumor formation in nude mice. The expression of HAGLR and LAMP3 was increased, whereas that of miR-143-5p was diminished in EC tissues and cells. HAGLR could competitively bind to miR-143-5p, and miR-143-5p targeted LAMP3. Down-regulated HAGLR or up-regulated miR-143-5p increased E-cadherin expression and significantly diminished expression of LAMP3, N-cadherin, vimentin, Twist1, and Snail1. Moreover, down-regulated HAGLR inhibited cell proliferation, invasion, migration, epithelial-mesenchymal transition (EMT), and tumor growth. Moreover, down-regulation of HAGLR inhibited LAMP3 expression by sponging miR-143-5p, thereby suppressing the progression of EC. Taken together, our results suggest HAGLR acts as a competing endogenous RNA of miR-143-5p to increase the expression of LAMP3, thus promoting EMT, proliferation, invasion, and migration in EC cells.-Yang, C., Shen, S., Zheng, X., Ye, K., Sun, Y., Lu, Y., Ge, H. Long noncoding RNA HAGLR acts as a microRNA-143-5p sponge to regulate epithelial-mesenchymal transition and metastatic potential in esophageal cancer by regulating LAMP3.

Chemoresistance Mediated by ceRNA Networks Associated With the PVT1 Locus

Competitive endogenous RNA (ceRNA) networks have emerged as critical regulators of carcinogenesis. Their activity is mediated by various non-coding RNAs (ncRNAs), including long non-coding RNAs and microRNAs, which competitively bind to targets, thereby modulating gene expression and activity of proteins. Of particular interest, ncRNAs encoded by the 8q24 chromosomal region are associated with the development and progression of several human cancers, most prominently lncPVT1. Chemoresistance presents a significant obstacle in the treatment of cancer and is associated with dysregulation of normal cell processes, including abnormal proliferation, differentiation, and epithelial-mesenchymal transition. CeRNA networks have been shown to regulate these processes via both direct sponging/repression and epigenetic mechanisms. Here we present a review of recent literature examining the contribution of ncRNAs encoded by the PVT1 locus and their associated ceRNA networks to the development of resistance to common chemotherapeutic agents used to treat human cancers.

Regulatory Mechanisms and Clinical Applications of the Long Non-coding RNA PVT1 in Cancer Treatment

Cancer is the second leading cause of death worldwide, and no obvious decline in incidence and mortality has occurred in recent years. It is imperative to further investigate the mechanisms underlying tumor progression. Long non-coding RNAs have received considerable attention in recent years because of their major regulatory roles in gene expression. Among them, PVT1 is well-studied, and substantial evidence indicates that PVT1 plays critical roles in the onset and development of cancers. Normally, PVT1 acts as an oncogenic factor by promoting cancer cell proliferation, invasion, metastasis, and drug resistance. Herein, we summarize current knowledge regarding the regulatory effects of PVT1 in cancer progression, as well as the related underlying mechanisms, such as interaction with Myc, modulation of miRNAs, and regulation of gene transcription and protein expression. In extracellular fluid, PVT1 mainly promotes cancer initiation, and it normally enhances cellular cancer characteristics in the cytoplasm and cell nucleus. Regarding clinical applications, its role in drug resistance and its potential use as a diagnostic and prognostic marker have received increasing attention. We hope that this review will contribute to a better understanding of the regulatory role of PVT1 in cancer progression, paving the way for the development of PVT1-based therapeutic approaches in cancer treatment.

PVT1 Promotes Cancer Progression via MicroRNAs

Non-coding RNA (ncRNA) plays a regulatory role in a variety of cellular activities. And long non-coding RNA (lncRNA) is one of the important kinds of ncRNA. Previous studies have shown that various lncRNAs are involved in the progression of cancer. LncRNA plasmacytoma variant translocation 1 (PVT1) is a newly discovered oncogenic factor that has been confirmed to be overexpressed in many cancer cells. Moreover, the role of PVT1 in cancer development is closely linked to microRNAs (miRNAs). PVT1 can act as a "sponge" for miRNAs to inhibit their activities, thereby affecting proliferation, invasion, and angiogenesis of cancer. In addition, PVT1 itself can be spliced and processed into several miRNAs such as miR-1204 and miR-1207, which can also regulate the development of cancer. This review summarizes various pathways through which PVT1 regulates the progression of cancer via miRNAs. We also propose additional regulatory mechanisms of PVT1 and their potential clinical applications.

PVT1 Signaling Is a Mediator of Cancer Progression

There is increasing evidence that PVT1 has oncogenic properties and regulates proliferation and growth of many cancers. Themolecular mechanisms of action of PVT1 are mediated, in part, by microRNAs (miRNAs). However, some well-established transcription factors involved in cancer cell proliferation share a common thread of microRNA associations with PVT1. Furthermore, these microRNAs are also involved in mechanisms that lead to the development of drug resistance in cancer cells. While several microRNAs have been implicated directly in PVT1-mediated tumorigenesis, significant steps need to be taken to elucidate these important relationships. We synthesize the current knowledge of the miRNAs and associated genes by which PVT1 contributes to tumorigenesis. Overall, the trend suggests a negative correlation of microRNA expression with PVT1. It is clear that future studies involving PVT1 should be carried out in conjunction with microRNA analysis and should include large scale lncRNA-miRNA-mRNA network analysis. Likewise, the relationship between established transcription factors such as p53 and MYC, and processes like epithelial-mesenchymal transition may offer valuable insight into the yet unknown mechanisms of PVTI-mediated cancer progression via microRNA-dependent signaling networks.

Knockdown of long non-coding RNA PVT1 inhibits the proliferation of Raji cells through cell cycle regulation

Long non-coding RNA plasmacytoma variant translocation 1 (PVT1) has been reported to be associated with oncogenesis. However, the functional role of PVT1 in Burkitt lymphoma has not yet been addressed. The purpose of the present study was to investigate the effect of PVT1 knockdown by small interfering RNA (siRNA) on the proliferation of Burkitt lymphoma Raji cells and to explore its possible mechanism of action. An effective siRNA targeting PVT1 was screened and the corresponding short hairpin RNA (shRNA) was reconstructed into a lentiviral vector. Cell proliferation and cell cycle distribution were assessed by Cell Counting kit-8 assay and flow cytometry, respectively. Protein expression levels of c-Myc, cyclin-dependent kinase inhibitor1A (CDKN1A, P21) and cyclin E1 (CCNE1) were detected by western blotting. A polymerase chain reaction (PCR) array was used to analyse the expression of genes associated with the cell cycle. PVT1 knockdown markedly suppressed proliferation, and induced cell cycle arrest at the G₀/G₁ phase in Raji cells. Protein expression levels of c-Myc and CCNE1 were reduced, whereas P21 protein expression was markedly increased following downregulation of PVT1 in Raji cells. The cell cycle PCR array revealed that 54 genes were upregulated and 26 genes were downregulated in Raji cells following PVT1 knockdown. Reverse transcription-quantitative PCR demonstrated that cyclin G2 (CCNG2), CDKN1A, Retinoblastoma-like 2 (RBL2, p130), HUS1 checkpoint homolog, cyclin dependent kinase inhibitor 3 (CDKN3) and cyclin dependent kinase inhibitor 1B (CDKN1B) expression were upregulated, whereas the expression levels of CCNE1, cyclin D1 (CCND1) and cell division cycle 20 (CDC20) were downregulated in Raji cells with PVT1 knockdown. In conclusion, PVT1 knockdown may inhibit the proliferation of Raji cells by arresting cells in G₀/G₁ phase. Furthermore, inhibition of cell proliferation may be associated with a reduction inc-Myc expression and alterations in the expression levels of cell cycle-associated genes.

Long non-coding RNA SNHG6 promotes cell proliferation and migration through sponging miR-4465 in ovarian clear cell carcinoma

Dysregulation of small nucleolar RNA host gene 6 (SNHG6) exerts critical oncogenic effects and facilitates tumourigenesis in human cancers. However, little information about the expression pattern of SNHG6 in ovarian clear cell carcinoma (OCCC) is available, and the contributions of this long non‐coding RNA to the tumourigenesis and progression of OCCC are unclear. In the present study, we showed via quantitative real‐time PCR that SNHG6 expression was abnormally up‐regulated in OCCC tissues relative to that in unpaired normal ovarian tissues. High SNHG6 expression was correlated with vascular invasion, distant metastasis and poor survival. Further functional experiments demonstrated that knockdown of SNHG6 in OCCC cells inhibited cell proliferation, migration and invasion in vitro as well as tumour growth in vivo. Moreover, SNHG6 functioned as a competing endogenous RNA (ceRNA), effectively acting as a sponge for miR‐4465 and thereby modulating the expression of enhancer of zeste homolog 2 (EZH2). Taken together, our data suggest that SNHG6 is a novel molecule involved in OCCC progression and that targeting the ceRNA network involving SNHG6 may be a treatment strategy in OCCC.

STAT6 phosphorylation upregulates microRNA-155 expression and subsequently enhances the pathogenesis of chronic lymphocytic leukemia

Chronic lymphocytic leukemia (CLL), a clonal expansion of CD5⁺ B cells, is the most common form of adult leukemia; however, the molecular mechanisms underlying its pathogenesis remain undetermined. It has been previously suggested that numerous biological factors, including cytokines, may be involved in the proliferation of malignant cells. For example, interleukin (IL)-4, IL-2, interferon-γ and tumor necrosis factor serve roles as inhibitors of cellular apoptosis; whereas IL-5 and IL-10 are inducers of cellular apoptosis. In the present study, the results demonstrated that the phosphorylation and activation of signal transducer and activator of transcription 6 (STAT6) was induced by IL-4 in a time-dependent manner. Notably, the expression level of microRNA (miR)-155 was increased in MEC-1 cells following treatment with IL-4; however, this effect was attenuated following STAT6 knockdown via RNA interference. In addition, STAT6 knockdown promoted cell apoptosis, which was partly attenuated by treatment with IL-4. Inhibition of miR-155 expression significantly increased cell apoptosis despite the presence of IL-4. The results of the present study suggested that treatment with IL-4 enhanced the expression of miR-155, which regulated CLL cell survival via the enhanced phosphorylation of STAT6.

MicroRNA-1205, encoded on chromosome 8q24, targets EGLN3 to induce cell growth and contributes to risk of castration-resistant prostate cancer

The chromosome 8q24.21 locus, which contains the proto-oncogene c-MYC, long non-coding RNA PVT1, and microRNAs (miRs), is the most commonly amplified region in human prostate cancer. A long-range interaction of genetic variants with c-MYC or long non-coding PVT1 at this locus contributes to the genetic risk of prostate cancer. At this locus is a cluster of genes for six miRs (miR-1204, −1205, −1206, −1207–3p, −1207–5p, and −1208), but their functional role remains elusive. Here, the copy numbers and expressions of miRs-1204~1208 were investigated using quantitative PCR for prostate cancer cell lines and primary tumors. The data revealed that copy numbers and expression of miR-1205 were increased in both castration-resistant prostate cancer cell lines and in primary tumors. In castration-resistant prostate cancer specimens, the copy number at the miR-1205 locus correlated with expression of miR-1205. Furthermore, functional analysis with an miR-1205 mimic, an miR-1205 inhibitor, and CRISPR/Cas9 knockout revealed that, in human prostate cancer cells, miR-1205 promoted cell proliferation and cell cycle progression and inhibited hydrogen peroxide-induced apoptosis. In these cells, miR-1205 downregulated expression of the Egl-9 family hypoxia inducible factor 3 (EGLN3) gene and targeted a site in its 3’-untranslated region to downregulate its transcriptional activity. Thus, by targeting EGLN3, miR-1205 has an oncogenic role and may contribute to the genetic risk of castration-resistant prostate cancer.

Prognostic roles of signal transducers and activators of transcription family in human breast cancer

Signal transducers and activators of transcription (STAT) family are critical transcription factors, which have been proved as prognostic predictors for a number of cancers. However, the prognostic roles of STAT family in breast cancer patients remain in dispute. In the present study, we mined the ‘Kaplan–Meier plotter’ (KM plotter) online database to explore the prognostic roles of STAT family mRNA expression in breast cancer including overall survival (OS), progression-free survival (PFS), as well as post-progression survival (PPS). The results suggest high mRNA expression of all the individual STATs, except STAT1 and STAT2, are significantly associated with favorable OS in breast cancer patients; high STAT1 mRNA expression is significantly associated with worse RFS and all the other individual STATs, except STAT3, are significantly associated with better RFS in breast cancer patients; only high STAT5b mRNA expression is significantly related to better PPS in breast cancer patients. Additionally, we explored the prognostic values of individual STATs in other clinicopathological features, such as pathological grades, estrogen receptor (ER) status and so on. The results suggest, except STAT2 and STAT6, high mRNA expression of STATs is related to a favorable prognosis especially for high pathological grade; high STAT5 mRNA expression indicates a favorable prognosis no matter under ER positive or negative status; high STAT4 mRNA expression suggests a favorable prognosis under human epidermal growth factor receptor 2 (HER2) negative status. Our results indicate that individual STATs, except STAT1 and STAT2, may act as a favorable prognostic biomarker in breast cancer. Nevertheless, further investigations on a larger population are warranted.