MicroRNA-141 and microRNA-146b-5p inhibit the prometastatic mesenchymal characteristics through the RNA-binding protein AUF1 targeting the transcription factor ZEB1 and the protein kinase AKT

Unleashing the pathological imprinting of cancer in autoimmunity: Is ZEB1 the answer?

The intriguing scientific relationship between autoimmunity and cancer immunology have been traditionally indulged to throw spotlight on novel pathological targets. Understandably, these "slowly killing" diseases are on the opposite ends of the immune spectrum. However, the immune regulatory mechanisms between autoimmunity and cancer are not always contradictory and sometimes mirror each other based on disease stage, location, and timepoint. Moreover, the blockade of immune checkpoint molecules or signalling pathways that unleashes the immune response against cancer is being leveraged to preserve self-tolerance and treat many autoimmune disorders. Therefore, understanding the common crucial factors involved in cancer is of paramount importance to paint the autoimmune disease spectrum and validate novel drug candidates. In the current review, we will broadly describe how ZEB1, or Zinc-finger E-box Binding Homeobox 1, reinforces immune exhaustion in cancer or contributes to loss of self-tolerance in auto-immune conditions. We made an effort to exchange information about the molecular pathways and pathological responses (immune regulation, cell proliferation, senescence, autophagy, hypoxia, and circadian rhythm) that can be regulated by ZEB1 in the context of autoimmunity. This will help untwine the intricate and closely postured pathogenesis of ZEB1, that is less explored from the perspective of autoimmunity than its counterpart, cancer. This review will further consider several approaches for targeting ZEB1 in autoimmunity.

Interactions between circRNAs and miR-141 in Cancer: From Pathogenesis to Diagnosis and Therapy

The function of non-coding RNAs (ncRNAs) in the pathogenesis and development of cancer is indisputable. Molecular mechanisms underlying carcinogenesis involve the aberrant expression of ncRNAs, including circular RNAs (circRNAs), and microRNAs (miRNAs). CircRNAs are a class of single-stranded, covalently closed RNAs responsible for maintaining cellular homeostasis through their diverse functions. As a part of the competing endogenous RNA (ceRNAs) network, they play a central role in the regulation of accessibility of miRNAs to their mRNA targets. The interplay between these molecular players is based on the primary role of circRNAs that act as miRNAs sponges, and the circRNA/miRNA imbalance plays a central role in different pathologies including cancer. Herein, we present the latest state of knowledge about interactions between circRNAs and miR-141, a well-known member of the miR-200 family, in malignant transformation, with emphasis on the biological role of circRNA/miR-141/mRNA networks as a future target for novel anti-cancer therapies.

Functional Role of RBP in Osteosarcoma: Regulatory Mechanism and Clinical Therapy

Malignant bone neoplasms can be represented by osteosarcoma (OS), which accounts for 36% of all sarcomas. To reduce tumor malignancy, extensive efforts have been devoted to find an ideal target from numerous candidates, among which RNA-binding proteins (RBPs) have shown their unparalleled competitiveness. With the special structure of RNA-binding domains, RBPs have the potential to establish relationships with RNAs or small molecules and are considered regulators of different sections of RNA processes, including splicing, transport, translation, and degradation of RNAs. RBPs have considerable significant roles in various cancers, and experiments revealed that there was a strong association of RBPs with tumorigenesis and tumor cell progression. Regarding OS, RBPs are a new orientation, but achievements in hand are noteworthy. Higher or lower expression of RBPs was first found in tumor cells compared to normal tissue. By binding to different molecules, RBPs are capable of influencing tumor cell phenotypes through different signaling pathways or other axes, and researches on medical treatment have been largely inspired. Exploring the prognostic and therapeutic values of RBPs in OS is a hotspot where diverse avenues on regulating RBPs have achieved dramatical effects. In this review, we briefly summarize the contribution of RBPs and their binding molecules to OS oncogenicity and generally introduce distinctive RBPs as samples. Moreover, we focus on the attempts to differentiate RBP's opposite functions in predicting prognosis and collect possible strategies for treatment. Our review provides forwards insight into improving the understanding of OS and suggests RBPs as potential biomarkers for therapies.

Functional role of MicroRNA/PI3K/AKT axis in osteosarcoma

Osteosarcoma (OS) is a primary malignant bone tumor that occurs in children and adolescents, and the PI3K/AKT pathway is overactivated in most OS patients. MicroRNAs (miRNAs) are highly conserved endogenous non-protein-coding RNAs that can regulate gene expression by repressing mRNA translation or degrading mRNA. MiRNAs are enriched in the PI3K/AKT pathway, and aberrant PI3K/AKT pathway activation is involved in the development of osteosarcoma. There is increasing evidence that miRNAs can regulate the biological functions of cells by regulating the PI3K/AKT pathway. MiRNA/PI3K/AKT axis can regulate the expression of osteosarcoma-related genes and then regulate cancer progression. MiRNA expression associated with PI3K/AKT pathway is also clearly associated with many clinical features. In addition, PI3K/AKT pathway-associated miRNAs are potential biomarkers for osteosarcoma diagnosis, treatment and prognostic assessment. This article reviews recent research advances on the role and clinical application of PI3K/AKT pathway and miRNA/PI3K/AKT axis in the development of osteosarcoma.

The lncRNA THOR interacts with and stabilizes hnRNPD to promote cell proliferation and metastasis in breast cancer

Emerging evidence shows that the lncRNA THOR is deeply involved in the development of various cancers. However, the effects and underlying molecular mechanisms of THOR in breast cancer (BRCA) initiation and progression have not been fully elucidated. Here we show that THOR is critical for BRCA tumorigenesis by interacting with hnRNPD to regulate downstream signaling pathways. THOR expression was significantly higher in BRCA tissues than in normal tissues, and THOR upregulation was associated with a poor prognosis in BRCA patients. Functionally, THOR knockdown impaired cell proliferation, migration and invasion in BRCA cells in vitro and inhibited tumorigenesis and metastasis in a tumor xenograft model and THOR-deficient MMTV-PyMT model in vivo. Mechanistically, THOR bound to the hnRNPD protein and increased hnRNPD protein levels by maintaining hnRNPD protein stability through inhibition of the proteasome-dependent degradation pathway. The increased hnRNPD protein levels led to stabilization of its target mRNAs, including pyruvate dehydrogenase kinase 1 (PDK1), further activating downstream PI3K-AKT and MAPK signaling pathways to regulate BRCA cell proliferation and metastasis. Together, our findings indicate that THOR is a promising prognostic predictor for BRCA patients and that the THOR-hnRNPD-PDK1-MAPK/PI3K-AKT axis might be a potential therapeutic target for BRCA treatment.

RNA-binding proteins and cancer metastasis

RNA-binding proteins (RBPs) can regulate gene expression through post-transcriptionally influencing all manner of RNA biology, including alternative splicing (AS), polyadenylation, stability, and translation of mRNAs, as well as microRNAs (miRNAs) and circular RNAs (circRNAs) processing. There is accumulating evidence reinforcing the perception that dysregulation or dysfunction of RBPs can lead to various human diseases, including cancers. RBPs influence diverse cancer-associated cellular phenotypes, such as proliferation, apoptosis, senescence, migration, invasion, and angiogenesis, contributing to the initiation and development of tumors, as well as clinical prognosis. Metastasis is the leading cause of cancer-related recurrence and death. Therefore, it is necessary to elucidate the molecular mechanisms behind tumor metastasis. In fact, a growing body of published research has proved that RBPs play pivotal roles in cancer metastasis. In this review, we will summarize the recent advances for helping us understand the role of RBPs in tumor metastasis, and discuss dysfunctions and dysregulations of RBPs affecting metastasis-associated processes including epithelial-mesenchymal transition (EMT), migration, and invasion of cancer cells. Furthermore, we will discuss emerging RBP-based strategy for the treatment of cancer metastasis.

Study of microRNA expression profiling as biomarkers for colorectal cancer patients in Lebanon

The high incidence and mortality rates of colorectal cancer (CRC) reveal its hazardous effect globally. Thus, it is important to diagnose CRC at an early stage to decrease its burden and improve survival rates. Previous studies have investigated the role of short non-coding microRNAs (miRNAs or miRs) in numerous types of cancer, including CRC. Previous studies have been performed to investigate the role of miRNAs as biomarkers in diagnosis, prognosis and prediction of CRC development. The aim of the present retrospective study was to identify the expression levels of miR-31, miR-145, miR-146b and miR-186 to highlight their role in CRC diagnosis and progression at different stages of the disease (precancerous polyp, adenoma and adenocarcinoma) in a Lebanese population. The expression levels of miRNAs was revealed using TaqMan reverse transcription-quantitative PCR on formalin-fixed paraffin-embedded tissues from Lebanese patients at different stages; their diagnostic value was determined using a receiver operating characteristics curve. Compared with healthy controls, miR-31 was upregulated (P<0.0001) at all stages. By contrast, miR-145, miR-186, and miR-146b were significantly downregulated at all stages (P<0.0001, P=0.0009 and P=0.0241, respectively). Of the four miRNAs studied, miR-31 and miR-145 were identified as potentially useful diagnostic factors, with an area under the curve of 0.7771 and 0.8269 and diagnostic accuracy of 71.3 and 78.5%, respectively. These data suggested that miR-31 and miR-145, upon further clinical validation, may be used as potential diagnostic biomarkers for the early detection of CRC at the polyp stage.

Oncogenic functions of ZEB1 in pediatric solid cancers: interplays with microRNAs and long noncoding RNAs

The transcription factor Zinc finger E-box binding 1 (ZEB1) displays a range of regulatory activities in cell function and embryonic development, including driving epithelial-mesenchymal transition. Several aspects of ZEB1 function can be regulated by its functional interactions with noncoding RNA types, namely microRNAs (miRNAs) and long noncoding RNAs (lncRNAs). Increasing evidence indicates that ZEB1 importantly influences cancer initiation, tumor progression, metastasis, and resistance to treatment. Cancer is the main disease-related cause of death in children and adolescents. Although the role of ZEB1 in pediatric cancer is still poorly understood, emerging findings have shown that it is expressed and regulates childhood solid tumors including osteosarcoma, retinoblastoma, neuroblastoma, and central nervous system tumors. Here, we review the evidence supporting a role for ZEB1, and its interplays with miRNAs and lncRNAs, in pediatric cancers.

Neuropilin and tolloid-like 2 regulates the progression of osteosarcoma

Neuropilin and tolloid-like 2 (NETO2) is aberrantly expressed in various malignancies. However, its role in osteosarcoma (OS) remains to be elucidated. This study aimed to identify the function of NETO2 in OS cells. The expression of NETO2 in sarcoma tissues was determined using the GEPIA database, and the mRNA and protein expression of NETO2 in OS cells and OS tissue was also assessed. The biological effects of NETO2 on OS cells were determined by overexpressing and downregulating NETO2. Cell proliferation, invasion, migration, colony formation, and epithelial-mesenchymal transition in OS cells were evaluated. Consistent with the GEPIA database, expression of NETO2 was upregulated in human OS samples and cell lines. NETO2 overexpression not only promoted the proliferation, colony formation, invasion, and epithelial-mesenchymal transition of OS cells, but also activated the PI3K/AKT signaling. NETO2 downregulation resulted in opposite effects. Furthermore, after using an AKT inhibitor, the effects of NETO2 on OS cells were attenuated. In conclusion, this study showed that NETO2 functions as an oncogene of osteosarcomas by activating the PI3K/AKT pathway.

The overexpression of AUF1 in colorectal cancer predicts a poor prognosis and promotes cancer progression by activating ERK and AKT pathways

Background

AUF1 is one of the AU‐rich binding proteins, which promotes rapid ARE‐mRNA degradation. Recently, it has been reported that AUF1 is involved in regulating the antioxidant system because of its capacity to bind specifically to RNA containing oxidized bases and degrade oxidized RNA. Many antioxidant proteins have been reported to be overexpressed in colorectal cancer (CRC), however, the role of AUF1 in the progression of CRC has not been explored.

Methods

The expression level of AUF1 protein in human CRC cell lines and CRC tissues was detected by western blotting and immunohistochemistry (IHC. The effects of AUF1 knockdown on CRC cell proliferation, migration, invasion and changes in the signaling pathways were evaluated using a cell counting kit‐8 (CCK‐8), Transwell assays and western blotting. Subcutaneous xenograft tumor model was employed to further substantiate the role of AUF1 in CRC.

Results

AUF1 protein was upregulated in CRC tissues and CRC cells, and high expression of AUF1 was significantly associated with advanced AJCC stage (P = .001), lymph node metastasis (P = .007), distant metastasis (P = .038) and differentiation (P = .009) of CRC specimens. CRC patients with the high expression of AUF1 had an extremely poor prognosis. The knockdown of AUF1 suppressed CRC cell line proliferation, migration and invasion, inhibited CRC cells tumorigenesis and growth in nude mice, and reduced phosphorylated‐ERK1/2 and phosphorylated AKT in CRC cells.

Conclusion

Our findings demonstrate that AUF1 is probably involved in the progression of CRC via the activation of the ERK1/2 and AKT pathways. AU‐rich RNA‐binding factor 1 could be used as a novel prognostic biomarker and a potential therapeutic target for CRC.

AUF1 promotes stemness in human mammary epithelial cells through stabilization of the EMT transcription factors TWIST1 and SNAIL1

The AU-rich element RNA-binding protein 1 (AUF1) is an RNA-binding protein, which can both stabilize and destabilize the transcripts of several cancer-related genes. Since epithelial-to-mesenchymal transition (EMT) and the acquisition of cancer stem cell traits are important for cancer onset and progression, we sought to determine the role of AUF1 in these two important processes. We have shown that AUF1 induces EMT and stemness in breast epithelial cells via stabilization of the SNAIL1 and TWIST1 mRNAs, and their consequent upregulation. Indeed, AUF1 binds the transcripts of these two genes at their 3′UTR and reduces their turnover. Ectopic expression of AUF1 also promoted stemness in mammary epithelial cells, and thereby increased the proportion of cancer stem cells. Importantly, breast cancer cells that ectopically express AUF1 were more efficient in forming orthotopic tumor xenografts in nude mice than their corresponding controls with limiting cell inocula. On the other hand, AUF1 downregulation with specific siRNA inhibited EMT and reduced the stemness features in breast cancer cells. Moreover, AUF1 knockdown sensitized breast cancer cells to the killing effect of cisplatin. Together, these findings provide clear evidence that AUF1 is an important inducer of the EMT process through stabilization of SNAIL1 and TWIST1 and the consequent promotion of breast cancer stem cells. Thereby, AUF1 targeted molecules could constitute efficient therapeutics for breast cancer patients.

MicroRNAs and Their Influence on the ZEB Family: Mechanistic Aspects and Therapeutic Applications in Cancer Therapy

Molecular signaling pathways involved in cancer have been intensively studied due to their crucial role in cancer cell growth and dissemination. Among them, zinc finger E-box binding homeobox-1 (ZEB1) and -2 (ZEB2) are molecules that play vital roles in signaling pathways to ensure the survival of tumor cells, particularly through enhancing cell proliferation, promoting cell migration and invasion, and triggering drug resistance. Importantly, ZEB proteins are regulated by microRNAs (miRs). In this review, we demonstrate the impact that miRs have on cancer therapy, through their targeting of ZEB proteins. MiRs are able to act as onco-suppressor factors and inhibit the malignancy of tumor cells through ZEB1/2 down-regulation. This can lead to an inhibition of epithelial-mesenchymal transition (EMT) mechanism, therefore reducing metastasis. Additionally, miRs are able to inhibit ZEB1/2-mediated drug resistance and immunosuppression. Additionally, we explore the upstream modulators of miRs such as long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs), as these regulators can influence the inhibitory effect of miRs on ZEB proteins and cancer progression.

MiR-146b-5p suppresses the malignancy of GSC/MSC fusion cells by targeting SMARCA5

Recent studies have confirmed that both cancer-associated bone marrow mesenchymal stem cells (BM-MSCs, MSCs) and glioma stem-like cells (GSCs) contribute to malignant progression of gliomas through their mutual interactions within the tumor microenvironment. However, the exact ways and relevant mechanisms involved in the actions of GSCs and MSCs within the glioma microenvironment are not fully understood. Using a dual-color fluorescence tracing model, our studies revealed that GSCs are able to spontaneously fuse with MSCs, yielding GSC/MSC fusion cells, which exhibited markedly enhanced proliferation and invasiveness. MiR-146b-5p was downregulated in the GSC/MSC fusion cells, and its overexpression suppressed proliferation, migration and invasion by the fusion cells. SMARCA5, which is highly expressed in high-grade gliomas, was a direct downstream target of miR-146b-5p in the GSC/MSC fusion cells. miR-146b-5p inhibited SMARCA5 expression and inactivated a TGF-β pathway, thereby decreasing GSC/MSC fusion cell proliferation, migration and invasion. Collectively, these findings demonstrate that miR-146b-5p suppresses the malignant phenotype of GSC/MSC fusion cells in the glioma microenvironment by targeting a SMARCA5-regulated TGF-β pathway.

MicroRNA-146-5p promotes proliferation, migration and invasion in lung cancer cells by targeting claudin-12

MicroRNAs (miRNAs) have been regarded as important regulators in different pathological processes of cells. Abnormal expression of miRNAs is frequently associated with cell proliferation, metastasis and apoptosis in various cancers. This study aimed to explore the effect of miR-146-5p on cell growth, metastasis and its mechanism in lung cancer cells. The expressions of miR-146-5p and claudin-12 in A549 and WI-38 cells were altered by transient transfection. Cisplatin was used to develop cells for regulation of cisplatin sensitivity. Cell viability, migration, invasion, and apoptosis were analyzed by CCK-8, Transwell and flow cytometry assays. The protein expressions of Wnt/β-catenin and PI3K/AKT/MAPK pathway-related factors were detected. miR-146-5p suppression inhibited cell viability, migration and invasion but promoted apoptosis in A549 cells. Moreover, overexpression of miR-146-5p reduced the sensitivity of A549 cells and WI-38 cells to cisplatin. In addition, claudin-12 was a direct target of miR-146-5p and was negatively regulated by miR-146-5p. Claudin-12 silence significantly reversed miR-146-5p suppression-mediated anti-tumor effects in A549 cells. Furthermore, miR-146-5p overexpression activated Wnt/β-catenin and PI3K/AKT/MAPK signal pathways via down-regulation of claudin-12. The results indicated that miR-146-5p promoted cell viability, migration and invasion, inhibited apoptosis and activated Wnt/β-catenin and PI3K/AKT/MAPK signal pathways by regulating claudin-12 expression in lung cancer cells.

MALAT1 rs619586 polymorphism functions as a prognostic biomarker in the management of differentiated thyroid carcinoma

This study aimed to explore the roles of miR-214 and MALAT1 rs619586 polymorphism in the control and survival of differentiated thyroid carcinoma (DTC) via Cox regression analyses. The levels of MALAT1, miR-214, and CTNNB1 in different experimental groups were compared to study the interaction among MALAT1, miR-214, and CTNNB1. MTT and colony assays were used to investigate the role of rs619586 polymorphism in cell growth. The G allele of rs619586 polymorphism obviously decreased the 5-year survival of patients with DTC. Additionally, compared with AA-genotyped patients, patients carrying the AG/GG genotypes of MALAT1 rs619586 polymorphism showed much higher levels of DTC grade and CTNNB1 expression, along with lower levels of MALAT1 and miR-214 expression. Furthermore, the transcription activity of MALAT1 was significantly lowered by the rs619586G allele or miR-214 mimic, while the miR-214 inhibitor upregulated the luciferase activity of MALAT1. Additionally, miR-214 inhibited CTNNB1 expression by targeting CTNNB1 3'-untranslated region. Finally, the G allele of MALAT1 rs619586 polymorphism apparently promoted cell proliferation. Our study indicated that miR-214 inhibited MALAT1 expression by directly binding to the G allele of MALAT1 rs619586 polymorphism, thus inhibiting CTNNB1 expression and promoting cell proliferation in the pathogenesis of DTC. Therefore, MALAT1 rs619586 polymorphism could be used to predict the prognosis of DTC.

The natural compound neobractatin inhibits tumor metastasis by upregulating the RNA-binding-protein MBNL2

Tumor metastasis is the predominant cause of lethality in cancer. We found that Neobractatin (NBT), a natural compound isolated from Garcinia bracteata, could efficiently inhibit breast and lung cancer cells metastasis. However, the mechanisms of NBT inhibiting cancer metastasis remain unclear. Based on the RNA-sequencing result and transcriptome analysis, Muscleblind-like 2 (MBNL2) was found to be significantly upregulated in the cells treated with NBT. The Cancer Genome Atlas (TCGA) database analysis indicated that the expression of MBNL2 in breast and lung carcinoma tumor tissues was significantly lower compared to normal tissues. We thus conducted to investigate the antimetastatic role of MBNL2. MBNL2 overexpression mimicked the effect of NBT on breast cancer and lung cancer cell motility and metastasis, in addition significantly enhanced the inhibition effect of NBT. MBNL2 knockdown furthermore partially eliminated the inhibitory effect of NBT on metastasis. Mechanistically, we demonstrated that NBT- and MBNL2-mediated antimetastasis regulation significantly correlated with the pAKT/epithelial-mesenchymal transition (EMT) pathway. Subsequent in vivo study showed the same metastasis inhibition effect in NBT and MBNL2 in MDA-MB-231 xenografts mouse model. This study suggest that NBT possesses significant antitumor activity in breast and lung cancer cells that is partly mediated through the MBNL2 expression and enhancement in metastasis via the pAKT/EMT signaling pathway.

Micromanaging aerobic respiration and glycolysis in cancer cells

BACKGROUND

Cancer cells possess a common metabolic phenotype, rewiring their metabolic pathways from mitochondrial oxidative phosphorylation to aerobic glycolysis and anabolic circuits, to support the energetic and biosynthetic requirements of continuous proliferation and migration. While, over the past decade, molecular and cellular studies have clearly highlighted the association of oncogenes and tumor suppressors with cancer-associated glycolysis, more recent attention has focused on the role of microRNAs (miRNAs) in mediating this metabolic shift. Accumulating studies have connected aberrant expression of miRNAs with direct and indirect regulation of aerobic glycolysis and associated pathways.

SCOPE OF REVIEW

This review discusses the underlying mechanisms of metabolic reprogramming in cancer cells and provides arguments that the earlier paradigm of cancer glycolysis needs to be updated to a broader concept, which involves interconnecting biological pathways that include miRNA-mediated regulation of metabolism. For these reasons and in light of recent knowledge, we illustrate the relationships between metabolic pathways in cancer cells. We further summarize our current understanding of the interplay between miRNAs and these metabolic pathways. This review aims to highlight important metabolism-associated molecular components in the hunt for selective preventive and therapeutic treatments.

MAJOR CONCLUSIONS

Metabolism in cancer cells is influenced by driver mutations but is also regulated by posttranscriptional gene silencing. Understanding the nuanced regulation of gene expression in these cells and distinguishing rapid cellular responses from chronic adaptive mechanisms provides a basis for rational drug design and novel therapeutic strategies.

MicroRNA-146b Overexpression Promotes Human Bladder Cancer Invasion via Enhancing ETS2-Mediated mmp2 mRNA Transcription

Although microRNAs have been validated to play prominent roles in the occurrence and development of human bladder cancer (BC), alterations and function of many microRNAs (miRNAs) in bladder cancer invasion are not fully explored yet. miR-146b was reported to be a tumor suppressor or oncomiRNA in various types of cancer. However, its accurate expression, function, and mechanism in bladder cancer remain unclear. Here we discovered that miR-146b was frequently upregulated in bladder cancer tissues compared with adjacent non-cancerous tissues. Inhibition of miR-146b resulted in a significant inhibitory effect on the invasion of bladder cancer cells by reducing mmp2 mRNA transcription and protein expression. We further demonstrated that knockdown of miR-146b attenuated ETS2 expression, which was the transcription factor of matrix metalloproteinase (MMP)2. Moreover, mechanistic studies revealed that miR-146b inhibition stabilized ARE/poly(U)-binding/degradation factor 1 (auf1) mRNA by directly binding to its mRNA 3′ UTR, further reduced ets2 mRNA stability, and finally inhibited mmp2 transcription and attenuated bladder cancer invasion abilities. The identification of the miR-146b/AUF1/ETS2/MMP2 mechanism for promoting bladder cancer invasion provides significant insights into understanding the nature of bladder cancer metastasis. Targeting the pathway described here may be a novel approach for inhibiting invasion and metastasis of bladder cancer.

Long non-coding RNA DLX6-AS1/miR-141-3p axis regulates osteosarcoma proliferation, migration and invasion through regulating Rab10

Long non-coding RNA (lncRNAs) DLX6-AS1 plays significant roles in various types of malignant tumors, including osteosarcoma (OS), the most prevalent primary malignant bone tumor.

MicroRNA-146b-5p as an oncomiR promotes papillary thyroid carcinoma development by targeting CCDC6

The microRNA-146b-5p (miR-146b-5p) is known to be involved in the development of papillary thyroid cancer (PTC); however, the underlying mechanism is unclear. Here we have investigated the biological functions and underlying molecular mechanisms of miR-146b-5p in PTC. The expression of miR-146b-5p was assessed in 92 pairs of PTC and adjacent normal tissues and showed correlation with the clinicopathological status such as the tumour size. Effects of miR-146b-5p and its direct target, coiled-coil domain containing 6 (CCDC6), on cell proliferation, migration, invasion, and cell cycle were evaluated through gain- and loss-of-function studies in vitro and in vivo. The expression of CCDC6 was further examined in 187 PTC cases and was found to be correlated with the clinicopathological status. Overexpression of miR-146b-5p was observed in PTC tissues that correlated with advanced PTC. miR-146b-5p promoted cell proliferation, migration, invasion, and cell cycle progression in vitro, whereas CCDC6 reversed this effect. miR-146b-5p promoted PTC growth in a subcutaneous mouse model in vivo, whereas overexpression of CCDC6 exerted the opposite effect. In conclusion, miR-146b-5p expression correlated with advanced PTC and promoted PTC development by targeting CCDC6 in vitro and in vivo; it could, therefore, serve as a promising target for PTC treatment.

Long non-coding RNA MIAT competitively binds miR-150-5p to regulate ZEB1 expression in osteosarcoma

Long non-coding RNAs (LncRNAs), are significant in a number of biological stages and illnesses. The myocardial infarction associated transcript (MIAT) serves a function in numerous types of illness and physiological and pathological processes, including paranoid schizophrenia, diabetic retinopathy, myocardial infarction and neuroendocrine prostate cancer. However, the function of the lncRNA MIAT in the development of osteosarcoma is unknown. It has been identified that during the development of osteosarcoma, MIAT is upregulated in tumor tissues compared to adjacent non-tumor tissues. The spreading and proliferation of osteosarcoma cells was reduced by MIAT knockdown. These findings indicate that MIAT functions by competing with critical RNAs to target miR-150-5p and activate zinc finger E-box binding homeobox 1 to modulate the function of osteosarcoma cells. Together, the present findings may contribute to the understanding of the pathogenesis of osteosarcoma.

Phosphoinositide-dependent kinase 1-associated glycolysis is regulated by miR-409-3p in clear cell renal cell carcinoma

Clear cell renal cell carcinoma (ccRCC) is the most popular kidney cancer in adults. Metabolic shift toward aerobic glycolysis is a fundamental factor for ccRCC therapy. MicroRNAs (miRNAs) are thought to be important regulators in ccRCC development and progression. Phosphoinositide-dependent kinase 1 (PDK1) is required for metabolic activation; however, the role of PDK1-induced glycolytic metabolism regulated by miRNAs is unclear in ccRCC. So, the purpose of the current study is to elucidate the underlying mechanism in ccRCC cell metabolism mediated by PDK1. Our results revealed that miR-409-3p inhibited glycolysis by regulating PDK1 expression in ccRCC cells. We also found that miR-409-3p was regulated by hypoxia. Our results indicated that PDK1 facilitated ccRCC cell glycolysis, regulated by miR-409-3p in hypoxia.

Functional Role of Non-Coding RNAs during Epithelial-To-Mesenchymal Transition

Epithelial-to-mesenchymal transition (EMT) is a key biological process involved in a multitude of developmental and pathological events. It is characterized by the progressive loss of cell-to-cell contacts and actin cytoskeletal rearrangements, leading to filopodia formation and the progressive up-regulation of a mesenchymal gene expression pattern enabling cell migration. Epithelial-to-mesenchymal transition is already observed in early embryonic stages such as gastrulation, when the epiblast undergoes an EMT process and therefore leads to the formation of the third embryonic layer, the mesoderm. Epithelial-to-mesenchymal transition is pivotal in multiple embryonic processes, such as for example during cardiovascular system development, as valve primordia are formed and the cardiac jelly is progressively invaded by endocardium-derived mesenchyme or as the external cardiac cell layer is established, i.e., the epicardium and cells detached migrate into the embryonic myocardial to form the cardiac fibrous skeleton and the coronary vasculature. Strikingly, the most important biological event in which EMT is pivotal is cancer development and metastasis. Over the last years, understanding of the transcriptional regulatory networks involved in EMT has greatly advanced. Several transcriptional factors such as Snail, Slug, Twist, Zeb1 and Zeb2 have been reported to play fundamental roles in EMT, leading in most cases to transcriptional repression of cell⁻cell interacting proteins such as ZO-1 and cadherins and activation of cytoskeletal markers such as vimentin. In recent years, a fundamental role for non-coding RNAs, particularly microRNAs and more recently long non-coding RNAs, has been identified in normal tissue development and homeostasis as well as in several oncogenic processes. In this study, we will provide a state-of-the-art review of the functional roles of non-coding RNAs, particularly microRNAs, in epithelial-to-mesenchymal transition in both developmental and pathological EMT.

Microrna-139-5p inhibits epithelial-mesenchymal transition and fibrosis in post-menopausal women with interstitial cystitis by targeting LPAR4 via the PI3K/Akt signaling pathway

The study explores whether miR-139-5p targeting LPAR4 affects epithelial-mesenchymal transition (EMT) and fibrosis in post-menopausal women with interstitial cystitis (IC) via the PI3K/Akt signaling pathway. Bladder tissues of IC and normal bladder tissues were collected. The pathology of bladder tissues was observed by HE, Masson and Picrosirius red staining. LPAR4 positive expression rate were determined by IHC. ELISA was performed to detect the levels of IL-6, IL-8, IL-10, and TNF-α. Rat IC models were randomized into seven different groups. miR-139-5p, LPAR1, LPAR2, LPAR3, LPAR4, LPAR5, P13K, Akt, E-cadherin, N-cadherin, Vimentin, TGF-β1, and CTGF expression were determined by RT-qPCR and Western blotting. Dual luciferase reporter gene assay verified that LPAR4 is a target gene of miR-139-5p. Fibrosis was a pathological manifestation of IC. The IC group showed higher LPAR4, PI3K, Akt, p-PI3K, p-Akt, N-cadherin, Vimentin, TGF-β1, and CTGF expression but lower miR-139-5p and E-cadherin expression than the normal group. The levels of IL-6, IL-8, IL-10, and TNF-α expression decreased while HB-EGF increased in the IC group in comparison of the normal group. Compared with the blank and NC groups, E-cadherin expression was increased in the miR-139-5p mimic and siRNA-LPAR4 groups, while LPAR4, PI3K, Akt, p-P13K, p-Akt, N-cadherin, Vimentin, TGF-β1, and CTGF expression were decreased. An opposite trend was found in the miR-139-5p inhibitor group. The miR-139-5p decreased in the miR-139-5p inhibitor + siRNA-LPAR4 and miR-139-5p inhibitor + wortmannin groups. Conclusively, miR-139-5p targeting LPAR4 inhibits EMT and fibrosis in post-menopausal IC women through the PI3K/Akt signaling pathway.

Down-regulation of miR-146b-5p by long noncoding RNA MALAT1 in hepatocellular carcinoma promotes cancer growth and metastasis

MicroRNAs play an important role in liver cancer genesis and progression. In this study, we identified down-regulation of miR-146b-5p associated with tumor growth, metastasis and poor survival in hepatocellular carcinoma (HCC) patients. miR-146b-5p could suppress proliferation, migration, and invasion and induced apoptosis in vitro and in vivo. Remarkably, TNF receptor associated factor 6 (TRAF6) was confirmed as a direct target of miR-146b-5p in HCC and miR-146b-5p exerted the tumor suppression roles through inhibiting the phosphorylation of Akt mediated by TRAF6. Furthermore, we identified long non-coding RNA MALAT1 as a molecular sponge of miR-146b-5p to down-regulate its expression in HCC. In general, our results indicate that miR-146b-5p inhibits tumor growth and metastasis of HCC by targeting TRAF6 mediated Akt phosphorylation.

Induction of epithelial-mesenchymal transition (EMT) by Beclin 1 knockdown via posttranscriptional upregulation of ZEB1 in thyroid cancer cells

Beclin 1 has emerged as a haploinsufficient tumor suppression gene in a variety of human carcinomas. In order to clarify the role of Beclin 1 in thyroid cancer, Beclin 1 was knockdown in thyroid cancer cell lines. The current study demonstrated that knockdown of Beclin 1 resulted in morphological and molecular changes of thyroid cancer cells consistent with epithelial-mesenchymal transition (EMT), a morphogenetic procedure during which cells lose their epithelial characteristics and acquire mesenchymal properties concomitantly with gene expression reprogramming. In addition, the current study presented evidence demonstrating that Beclin 1 knockdown triggered this prometastatic process via stabilization of the EMT inducer ZEB1 mRNA through upregulation of AU-binding factor 1 (AUF1), which is recruited to the 3′-untranslated region (UTR) of the ZEB1 mRNA and decreases its degradation. We also found a negative correlation of Beclin 1 with AUF1 or ZEB1 in thyroid cancer tissues. These results indicated that at least some tumor suppressor functions of Beclin 1 were mediated through posttranscriptional regulation of ZEB1 via AUF1 in thyroid cancers.

ZEB1 confers chemotherapeutic resistance to breast cancer by activating ATM

Although zinc finger E-box binding homeobox 1 (ZEB1) has been identified as a key factor in the regulation of breast cancer differentiation and metastasis, its potential role in modulating tumor chemoresistance has not been fully understood. Here, through the study of specimens from a large cohort of human breast cancer subjects, we showed that patients with tumors that expressed high levels of ZEB1 responded poorly to chemotherapy. Moreover, ZEB1 expression was positively correlated with expression of B-cell lymphoma-extra large (Bcl-xL) and cyclin D1, which are key components of tumor chemoresistant mechanisms. At the molecular level, ectopic expression of ZEB1 impaired the responsiveness of breast cancer cells to genotoxic drug treatment, such as epirubicin (EPI). During this process, ZEB1 transcriptionally activated the expression of ataxia-telangiectasia mutated (ATM) kinase by forming a ZEB1/p300/PCAF complex on its promoter, leading to increased homologous recombination (HR)-mediated DNA damage repair and the clearance of DNA breaks. Using a nude mouse xenograft model, we further confirmed that ectopic expression of ZEB1 decreased breast cancer responsiveness to EPI treatment in vivo. Collectively, our findings suggest that ZEB1 is a crucial determinant of chemotherapeutic resistance in breast cancer.

Obesity and p16INK4A Downregulation Activate Breast Adipocytes and Promote Their Protumorigenicity

Obesity is increasingly recognized as a risk factor for breast cancer development. However, the molecular basis of obesity-related breast carcinogenesis remains elusive. In this study, we have shown that obesity reduces the level of the tumor suppressor p16^INK4A protein in breast adipocytes, which showed active features and strong procarcinogenic potential both in vitro and in orthotopic tumor xenografts compared to mature adipocytes from lean women. Furthermore, obesity triggered epithelial-to-mesenchymal transition (EMT) in breast ductal epithelial cells. Interestingly, specific downregulation of p16^INK4A increased the expression/secretion levels of various adipokines, including leptin, and activated breast adipocytes from lean women. Consequently, like breast adipocytes from obese women, p16-deficient adipocytes induced EMT in normal primary breast luminal cells in a leptin-dependent manner and enhanced tumor growth. Additionally, we have shown that p16^INK4A negatively controls leptin at the mRNA level through microRNAs 141 and 146b-5p (miR-141 and miR-146b-5p), which bind the leptin mRNA at a specific sequence in the 3' untranslated region (UTR). These results show that obesity activates breast stromal adipocytes through p16 downregulation, which upregulates leptin and promotes procarcinogenic processes.

MiR-146b-5p functions as a suppressor miRNA and prognosis predictor in non-small cell lung cancer

Non-small cell lung cancer (NSCLC) is the leading cause of cancer-related death worldwide. However, science has not yet been able to substantially improve the prognosis of lung cancer patients. Accumulating evidence suggests that microRNAs (miRNAs) are key players in the regulation of tumor development and metastasis. Expression of six miRNAs previously shown to play roles in tumor development (miR-146b-5p, miR-128b, miR-21, miR-221, miR-34a, and Let-7a) in other tumor types was examined using real-time RT-PCR in 78 specimens of NSCLC. The results revealed that patients with low expression of miR-146b-5p had significant shorter median and mean survival time than those with high miR-146b-5p expression (33.00 and 30.44 months versus 42.0 and 36.90 months, respectively; log-rank test P=0.048), thus low miR-146b-5p expression level was associated with poor prognosis in NSCLC patients. Univariate Cox hazard regression analysis demonstrated that miR-146b-5p expression levels tended to be a significant prognostic indicator of NSCLC (adjusted hazard ratio=0.482, 95% CI: 1.409- 29.593, P=0.016). Multivariate Cox proportional hazard regression analysis showed that miR-146b-5p expression levels were an independent prognostic factor for NSCLC patients (hazard ratio=0.259, 95% CI: 0.083-0.809, P=0.020). Furthermore, the effects of miR-146b-5p and miR-146b-3p on NSCLC cell growth and invasion in vitro were investigated. Our findings demonstrate that ectopic expression of miR-146b-5p suppressed cell proliferation, clonogenicity, migration/ invasion and also induced G1 arrest in vitro, but did not induce cell apoptosis; whereas enforced expression of miR-146b-3p did not have a significant effect on cell growth and metastasis. Further experiments indicated that miR-146b-5p could reduce mRNA levels of MMP16 and TRAF6 in vitro and was negatively related to the expression of TRAF6 in human NSCLC tissues. In a mouse model, Ago-miR-146b-5p could significantly inhibit the growth of lung cancer xenografts in nude mice. In conclusion, our findings demonstrate that miR-146b-5p functions as a suppressor miRNA and prognosis predictor in NSCLC.

Comparison of the miRNA expression profiles in fresh frozen and formalin-fixed paraffin-embedded tonsillar tumors

MicroRNAs are considered as promising prognostic and diagnostic biomarkers of human cancer since their profiles differ between tumor types. Most of the tumor profiling studies were performed on rarely available fresh frozen (FF) samples. Alternatively, archived formalin-fixed paraffin-embedded (FFPE) tissue samples are also well applicable to larger-scale retrospective miRNA profiling studies. The aim of this study was to perform systematic comparison of the miRNA expression profiles between FF and macrodissected FFPE tonsillar tumors using the TaqMan Low Density Array system, with the data processed by different software programs and two types of normalization methods. We observed a marked correlation between the miRNA expression profiles of paired FF and FFPE samples; however, only 27-38% of the differentially deregulated miRNAs overlapped between the two source systems. The comparison of the results with regard to the distinct modes of data normalization revealed an overlap in 58-67% of differentially expressed miRNAs, with no influence of the choice of software platform. Our study highlights the fact that for an accurate comparison of the miRNA expression profiles from published studies, it is important to use the same type of clinical material and to test and select the best-performing normalization method for data analysis.

LncRNA-MALAT1 Promotes Angiogenesis of Thyroid Cancer by Modulating Tumor-Associated Macrophage FGF2 Protein Secretion

Tumor-associated macrophages (TAMs) in the tumor microenvironment have been associated with enhanced tumor progression. In this study, we investigated the role and molecular mechanisms of MALAT1 in TAMs derived from thyroid cancer. The expression of MALAT1 and FGF2 in thyroid cancer tissues and cells were measured by quantitative real-time PCR and Western blot. TAMs were transfected with indicated constructs. Then the culture medium (CM) from TAMs was harvested for assay. Secreted FGF2 protein levels and TNF-α, IL-12, and IL-10 levels were detected by ELISA. The cell proliferation, migration, and invasion of FTC133 cells were determined with a CCK-8 assay and a Transwell assay, respectively. In addition, HUVEC vasculature formation was measured by matrigel angiogenesis assay. The higher levels of MALAT-1 and FGF2 were observed in thyroid cancer tissues and in thyroid cancer cells compared to that in the control. Besides, in the presence of si-MALAT1, the levels of TNF-α and IL-12 were significantly up-regulated whereas IL-10 was down-regulated in the CM from TAMs. Moreover, down-regulation of MALAT1 in TAMs reduced proliferation, migration, and invasion of FTC133 cells and inhibited angiogenesis. However, overexpression of FGF2 blocked the effects of MALAT1 siRNAs on cell migration, invasion, and angiogenesis. Our results suggest that MALAT1-mediated FGF2 protein secretion from TAMs inhibits inflammatory cytokines release, promotes proliferation, migration, and invasion of FTC133 cells and induces vasculature formation. J. Cell. Biochem. 118: 4821-4830, 2017. © 2017 Wiley Periodicals, Inc.

miR-146b-5p regulates cell growth, invasion, and metabolism by targeting PDHB in colorectal cancer

MiRNA have been found to play a role in a plethora of cellular processes of cancer cells such as cell apoptosis, cell proliferation, invasion, migration metabolism and stem cell differentiation. Dysregulation of miR-146b-5p has been documented in a variety of human malignancies. However, the biological functions and molecular mechanisms of miR-146b-5p in ovarian cancer remain unknown. In this study, our results show that miR-146b-5p was unregulated in colorectal cancer (CRC) tissues compared with the adjacent non-cancerous tissues. Ectopic overexpression of miR-146b-5p in CRC promoted cell growth, invasion and glycolysis, while knockdown of miR-146b-5p inhibited the growth, invasion and glycolysis of CRC cells. The oncogenic effect of miR-146b-5p is also confirmed in vivo. Mechanically, miR-146b-5p targets the 3'-UTR of pyruvate dehydrogenase B (PDHB) and exerts oncogenic effect. Overexpression of PDHB abolished the oncogenic effects of miR-146b-5p on the growth, invasion and glycolysis of CRC cells. Taken together, our results show that miR-146b-5p is an oncogenic miRNA in CRC which exerts its effect by directly targeting PDHB.

Interplay Between Long Noncoding RNA ZEB1-AS1 and miR-200s Regulates Osteosarcoma Cell Proliferation and Migration

In our previous study, we found long noncoding RNA ZEB1-AS1 is upregulated and functions as an oncogene in osteosarcoma. MiR-200 family (miR-200s) functions as tumor suppressor via directly targeting ZEB1 in various cancers. In this study, we further investigate the potential interplay between ZEB1-AS1, miR-200s, and ZEB1 in osteosarcoma. Our results showed that ZEB1-AS1 functions as a molecular sponge for miR-200s and relieves the inhibition of ZEB1 caused by miR-200s. ZEB1-AS1 and miR-200s reciprocally negatively regulate each other. MiR-200s are downregulated in osteosarcoma tissues, and negatively correlated with ZEB1-AS1 and ZEB1 expression levels in osteosarcoma. Functional experiments showed that consistent with ZEB1-AS1 depletion, miR-200s overexpression and ZEB1 depletion both inhibit osteosarcoma cell proliferation and migration. Overexpression of miR-200s partially abolished the effects of ZEB1-AS1 on osteosarcoma cell proliferation and migration. Moreover, the combination of ZEB1-AS1 depletion and miR-200s overexpression significantly inhibits osteosarcoma cell proliferation and migration. In conclusion, this study revealed a novel regulatory mechanism between ZEB1-AS1, miR-200s, and ZEB1. The interplay between ZEB1-AS1 and miR-200s contributes to osteosarcoma cell proliferation and migration, and targeting this interplay could be a promising strategy for osteosarcoma treatment. J. Cell. Biochem. 118: 2250-2260, 2017. © 2017 Wiley Periodicals, Inc.

MALAT1 Long Non-coding RNA Expression in Thyroid Tissues: Analysis by In Situ Hybridization and Real-Time PCR

Long non-coding RNAs (lncRNAs) are important for transcription and for epigenetic or posttranscriptional regulation of gene expression and may contribute to carcinogenesis. Metastasis-associated lung adenocarcinoma transcript 1 (MALAT1), an lncRNA involved in the regulation of the cell cycle, cell proliferation, and cell migration, is known to be deregulated in multiple cancers. Here, we analyzed the expression of MALAT1 on 195 cases of benign and malignant thyroid neoplasms by using tissue microarrays for RNA in situ hybridization (ISH) and real-time PCR. MALAT1 is highly expressed in normal thyroid (NT) tissues and thyroid tumors, with increased expression during progression from NT to papillary thyroid carcinomas (PTCs) but is downregulated in poorly differentiated thyroid cancers (PDCs) and anaplastic thyroid carcinomas (ATCs) compared to NT. Induction of epithelial to mesenchymal transition (EMT) by transforming growth factor (TGF)-beta in a PTC cell line (TPC1) led to increased MALAT1 expression, supporting a role for MALAT1 in EMT in thyroid tumors. This is the first ISH study of MALAT1 expression in thyroid tissues. It also provides the first piece of evidence suggesting MALAT1 downregulation in certain thyroid malignancies. Our findings support the notion that ATCs may be molecularly distinct from low-grade thyroid malignancies and suggest that MALAT1 may function both as an oncogene and as a tumor suppressor in different types of thyroid tumors.

RNA-binding protein CELF1 promotes tumor growth and alters gene expression in oral squamous cell carcinoma

The RNA binding protein CELF1 (also known as CUGBP1) is emerging as a critical regulator of cancer cell proliferation and apoptosis. Here, to provide a global prospective of CELF1 regulation of oral squamous cell carcinoma, we performed RNA-sequencing in oral cancer cells and CELF1 overexpression analysis in non-malignant human oral keratinocytes. Our approaches identified 1283 mRNAs differentially regulated as a function of CELF1 expression and more importantly CELF1 promoted alternative splicing of several target pre-mRNAs, which are known to be involved in various cancer biological processes. Overexpression of CELF1 in non-malignant human oral keratinocytes protected cells against oxidative damage and altered gene expression patterns. Finally, we provide evidence that reduction of CELF1 protein using a xenograft tumorigenesis mouse model decreased tumor growth. Altogether, these data provided a comprehensive view of the CELF1 mRNA regulatory network in oral cancer and suggests that CELF1 and/or its target mRNAs are viable candidates for therapeutic intervention.

AUF1 regulation of coding and noncoding RNA

AUF1 is a family of four RNA-binding proteins (RBPs) generated by alternative pre-messenger RNA (pre-mRNA) splicing, with canonical roles in controlling the stability and/or translation of mRNA targets based on recognition of AU-rich sequences within mRNA 3' untranslated regions. However, recent studies identifying AUF1 target sites across the transcriptome have revealed that these canonical functions are but a subset of its roles in posttranscriptional regulation of gene expression. In this review, we describe recent developments in our understanding of the RNA-binding properties of AUF1 together with their biochemical implications and roles in directing mRNA decay and translation. This is then followed by a survey of newly discovered activities for AUF1 proteins in control of miRNA synthesis and function, including miRNA assembly into microRNA (miRNA)-loaded RNA-induced silencing complexes (miRISCs), miRISC targeting to mRNA substrates, interplay with an expanding network of other cellular RBPs, and reciprocal regulatory relationships between miRNA and AUF1 synthesis. Finally, we discuss recently reported relationships between AUF1 and long noncoding RNAs and regulatory roles on viral RNA substrates. Cumulatively, these findings have significantly expanded our appreciation of the scope and diversity of AUF1 functions in the cell, and are prompting an exciting array of new questions moving forward. WIREs RNA 2017, 8:e1393. doi: 10.1002/wrna.1393 For further resources related to this article, please visit the WIREs website.

MiR-146b negatively regulates migration and delays progression of T-cell acute lymphoblastic leukemia

Previous results indicated that miR-146b-5p is downregulated by TAL1, a transcription factor critical for early hematopoiesis that is frequently overexpressed in T-cell acute lymphoblastic leukemia (T-ALL) where it has an oncogenic role. Here, we confirmed that miR-146b-5p expression is lower in TAL1-positive patient samples than in other T-ALL cases. Furthermore, leukemia T-cells display decreased levels of miR-146b-5p as compared to normal T-cells, thymocytes and other hematopoietic progenitors. MiR-146b-5p silencing enhances the in vitro migration and invasion of T-ALL cells, associated with increased levels of filamentous actin and chemokinesis. In vivo, miR-146b overexpression in a TAL1-positive cell line extends mouse survival in a xenotransplant model of human T-ALL. In contrast, knockdown of miR-146b-5p results in leukemia acceleration and decreased mouse overall survival, paralleled by faster tumor infiltration of the central nervous system. Our results suggest that miR-146b-5p is a functionally relevant microRNA gene in the context of T-ALL, whose negative regulation by TAL1 and possibly other oncogenes contributes to disease progression by modulating leukemia cell motility and disease aggressiveness.

miR-146b-5p mediates p16-dependent repression of IL-6 and suppresses paracrine procarcinogenic effects of breast stromal fibroblasts

Increasing evidence support the critical roles of active stromal fibroblasts in breast cancer development and spread. However, the mediators and the mechanisms of regulation are still not well defined. We have shown here that the tumor suppressor p16^INK4A protein inhibits the pro-carcinogenic effects of breast stromal fibroblasts through repressing the expression/secretion of IL-6. Indeed, p16^INK4A suppresses IL-6 at the mRNA and protein levels. This effect is mediated trough miR-146b-5p, which inhibits IL-6 expression through a specific sequence at the IL-6 3′UTR. In addition, we present clear evidence that miR-146b-5p inhibition is sufficient to transactivate breast stromal fibroblasts, which promote epithelial-to-mesenchymal-transition in breast cancer cells in a paracrine manner. By contrast, ectopic expression of miR-146b-5p in active fibroblasts abrogated their pro-carcinogenic effects. The physiological importance of miR-146b-5p inhibition was revealed by showing that the levels of pre-miR-146b-5p as well as its mature form are reduced in cancer-associated fibroblasts as compared with their normal adjacent counterparts from cancer-free tissues isolated from the same patients. Interestingly, treatment of active breast stromal fibroblasts with curcumin increased the level of the p16^INK4A coding CDKN2A mRNA and miR-146b-5p and suppressed IL-6, which confirms the repressive effect of these two tumor suppressor molecules on IL-6, and shows the possible “normalization” of cancer-related active fibroblasts. These results show that miR-146b-5p has non-cell-autonomous tumor suppressor function through inhibition of IL-6, suggesting that targeting this microRNA in breast stromal fibroblasts could be of great therapeutic value.

miRNAs Related to Skeletal Diseases

miRNAs as non-coding, short, double-stranded RNA segments are important for cellular biological functions, such as proliferation, differentiation, and apoptosis. miRNAs mainly contribute to the inhibition of important protein translations through their cleavage or direct repression of target messenger RNAs expressions. In the last decade, miRNAs got in the focus of interest with new publications on miRNAs in the context of different diseases. For many types of cancer or myocardial damage, typical signatures of local or systemically circulating miRNAs have already been described. However, little is known about miRNA expressions and their molecular effect in skeletal diseases. An overview of published studies reporting miRNAs detection linked with skeletal diseases was conducted. All regulated miRNAs were summarized and their molecular interactions were illustrated. This review summarizes the involvement and interaction of miRNAs in different skeletal diseases. Thereby, 59 miRNAs were described to be deregulated in tissue, cells, or in the circulation of osteoarthritis (OA), 23 miRNAs deregulated in osteoporosis, and 107 miRNAs deregulated in osteosarcoma (OS). The molecular influences of miRNAs regarding OA, osteoporosis, and OS were illustrated. Specific miRNA signatures for skeletal diseases are described in the literature. Some overlapped, but also unique ones for each disease exist. These miRNAs may present useful targets for the development of new therapeutic approaches and are candidates for diagnostic evaluations.

Comparison of the miRNA profiles in HPV-positive and HPV-negative tonsillar tumors and a model system of human keratinocyte clones

BACKGROUND

Better insights into the molecular changes involved in virus-associated and -independent head and neck cancer may advance our knowledge of HNC carcinogenesis and identify critical disease biomarkers. Here we aimed to characterize the expression profiles in a matched set of well-characterized HPV-dependent and HPV-independent tonsillar tumors and equivalent immortalized keratinocyte clones to define potential and clinically relevant biomarkers of HNC of different etiology.

METHODS

Fresh frozen tonsillar cancer tissues were analyzed together with non-malignant tonsillar tissues and compared with cervical tumors and normal cervical tissues. Furthermore, relative miRNAs abundance levels of primary and immortalized human keratinocyte clones were evaluated. The global quantitation of miRNA gene abundance was performed using a TaqMan Low Density Array system. The confirmation of differentially expressed miRNAs was performed on a set of formalin-fixed paraffin-embedded tumor samples enriched for the tumor cell fraction by macrodissection.

RESULTS

We defined 46 upregulated and 31 downregulated miRNAs characteristic for the HPV-positive tonsillar tumors and 42 upregulated miRNAs and 42 downregulated miRNAs characteristic for HPV-independent tumors. In comparison with the expression profiles in cervical tumors, we defined miR-141-3p, miR-15b-5p, miR-200a-3p, miR-302c-3p, and miR-9-5p as specific for HPV induced malignancies. MiR-335-5p, miR-579-3p, and miR-126-5p were shared by the expression profiles of HPV-positive tonsillar tumors and of the HPV immortalized keratinocyte clones, whereas miR-328-3p, miR-34c-3p, and miR-885-5p were shared by the miRNA profiles of HPV-negative tonsillar tumors and the HPV-negative keratinocytes.

CONCLUSIONS

We identified the miRNAs characteristic for HPV-induced tumors and tonsillar tumors of different etiology, and the results were compared with those of the model system. Our report presents the basis for further investigations leading to the identification of clinically relevant diagnostic and/or therapeutic biomarkers for tumors of viral and non-viral etiology.

Crystal Structure of the N-Terminal RNA Recognition Motif of mRNA Decay Regulator AUF1

AU-rich element binding/degradation factor 1 (AUF1) plays a role in destabilizing mRNAs by forming complexes with AU-rich elements (ARE) in the 3′-untranslated regions. Multiple AUF1-ARE complexes regulate the translation of encoded products related to the cell cycle, apoptosis, and inflammation. AUF1 contains two tandem RNA recognition motifs (RRM) and a Gln- (Q-) rich domain in their C-terminal region. To observe how the two RRMs are involved in recognizing ARE, we obtained the AUF1-p37 protein covering the two RRMs. However, only N-terminal RRM (RRM1) was crystallized and its structure was determined at 1.7 Å resolution. It appears that the RRM1 and RRM2 separated before crystallization. To demonstrate which factors affect the separate RRM1-2, we performed limited proteolysis using trypsin. The results indicated that the intact proteins were cleaved by unknown proteases that were associated with them prior to crystallization. In comparison with each of the monomers, the conformations of the β2-β3 loops were highly variable. Furthermore, a comparison with the RRM1-2 structures of HuR and hnRNP A1 revealed that a dimer of RRM1 could be one of the possible conformations of RRM1-2. Our data may provide a guidance for further structural investigations of AUF1 tandem RRM repeat and its mode of ARE binding.

Hallmarks of cancer and AU-rich elements

Post‐transcriptional control of gene expression is aberrant in cancer cells. Sustained stabilization and enhanced translation of specific mRNAs are features of tumor cells. AU‐rich elements (AREs), cis‐acting mRNA decay determinants, play a major role in the posttranscriptional regulation of many genes involved in cancer processes. This review discusses the role of aberrant ARE‐mediated posttranscriptional processes in each of the hallmarks of cancer, including sustained cellular growth, resistance to apoptosis, angiogenesis, invasion, and metastasis. WIREs RNA 2017, 8:e1368. doi: 10.1002/wrna.1368

For further resources related to this article, please visit the WIREs website.

MicroRNA-200b acts as a tumor suppressor in osteosarcoma via targeting ZEB1

Osteosarcoma is the most common type of cancer that develops in bone, mainly arising from the metaphysis of the long bones. MicroRNA (miR)-200b has been found to generally act as a tumor suppressor in multiple types of human cancers. However, the detailed role of miR-200b in osteosarcoma still remains to be fully understood. This study aimed to investigate the exact role of miR-200b in the progression of osteosarcoma and the underlying mechanism. Real-time reverse transcription-polymerase chain reaction data showed that miR-200b was significantly downregulated in osteosarcoma tissues compared to their matched adjacent nontumor tissues. Low miR-200b level was associated with the advanced clinical stage and positive distant metastasis. Besides, it was also downregulated in osteosarcoma cell lines (U2OS, Saos2, HOS, and MG63) compared to normal osteoblast cell line NHOst. In vitro study showed that restoration of miR-200b led to a significant decrease in proliferation, migration, and invasion of osteosarcoma cells. Moreover, ZEB1 was identified as a target gene of miR-200b, and its expression levels were negatively mediated by miR-200b in osteosarcoma cells. In addition, ZEB1 was significantly upregulated in osteosarcoma cells compared to the normal osteoblast cell line NHOst, and inhibition of ZEB1 expression also suppressed the proliferation, migration, and invasion in osteosarcoma cells. Finally, we showed that ZEB1 was frequently upregulated in osteosarcoma tissues compared to their matched adjacent normal tissues, and its expression was reversely correlated to the miR-200b levels in osteosarcoma tissues. Based on these findings, our study suggests that miR-200b inhibits the proliferation, migration, and invasion of osteosarcoma cells, probably via the inhibition of ZEB1 expression. Therefore, miR-200b/ZEB1 may become a potential target for the treatment of osteosarcoma.

MicroRNA profiling of cisplatin-resistant oral squamous cell carcinoma cell lines enriched with cancer-stem-cell-like and epithelial-mesenchymal transition-type features

Oral cancer is of major public health problem in India. Current investigation was aimed to identify the specific deregulated miRNAs which are responsible for development of resistance phenotype through regulating their resistance related target gene expression in oral squamous cell carcinoma (OSCC). Cisplatin-resistant OSCC cell lines were developed from their parental human OSCC cell lines and subsequently characterised. The resistant cells exhibited enhanced proliferative, clonogenic capacity with significant up-regulation of P-glycoprotein (ABCB1), c-Myc, survivin, β-catenin and a putative cancer-stem-like signature with increased expression of CD44, whereas the loss of E-cadherin signifies induced EMT phenotype. A comparative analysis of miRNA expression profiling in parental and cisplatin-resistant OSCC cell lines for a selected sets (deregulated miRNAs in head and neck cancer) revealed resistance specific signature. Moreover, we observed similar expression pattern for these resistance specific signature miRNAs in neoadjuvant chemotherapy treated and recurrent tumours compared to those with newly diagnosed primary tumours in patients with OSCC. All these results revealed that these miRNAs play an important role in the development of cisplatin-resistance mainly through modulating cancer stem-cell-like and EMT-type properties in OSCC.

MiRNA-146b-5p upregulates migration and invasion of different Papillary Thyroid Carcinoma cells

Background

Tumor invasiveness is directly related to the ability of tumor cells to migrate and invade surrounding tissues, usually degrading extracellular matrix. Despite significant progress in the knowledge about migration and invasion, there is much more to elucidate about their regulatory mechanisms, especially in cancer cells. MicroRNAs (miRs) were recently described as important regulators of migration. Differential expression of miRs in cancer is frequently associated with progression, invasion and metastasis. In papillary thyroid carcinoma (PTC), miR-146b-5p is highly expressed and positively correlated to the degree of malignancy.

Methods

This study aimed to investigate the role of miR-146b-5p on the migratory and invasive behaviors of thyroid cells, using a non tumor rat thyroid follicular cell line (PCCl3) transfected with the miR-146b-5p genomic region, and two PTC cell lines (TPC-1 and BCPAP, bearing distinct oncogenic backgrounds), which express high levels of miR-146b-5p, after miR-146b inhibition by antagomiR and miR-146b overexpression by mimics-miR. Migration and invasion were studied by time-lapse and transwell assays (with and without Matrigel®). Gelatin degradation assays were also employed, as well as F-actin staining.

Results

Migration and invasion of PCCl3 were increased 2-3x after miR-146b-5p overexpression (10X) and large lamellipodia were evident in those cells. After miR-146b-5p inhibition, TPC-1 and BCPAP migration and invasion were significantly reduced, with cells showing several simultaneous processes and low polarity. Gelatin degradation was inhibited in TPC-1 cells after inhibition of miR-146b-5p, but was unaffected in BCPAP cells, which did not degrade gelatin. The inhibition of miR-146b-5p in PCCl3 also inhibited migration and invasion, and additional (exogenous) overexpression of this miR in TPC-1 and BCPAP cells increased migration and invasion, without effects on cell morphology or gelatin degradation. The overexpression of SMAD4 in BCPAP cells, a validated target of miR-146b-5p and key protein in the TGF-β signaling pathway, inhibited migration similarly to the effects observed with the antagomiR 146b-5p.

Conclusions

miR-146b-5p positively regulates migration and invasion of thyroid normal and tumor follicular cells (independently from their original mutation, either BRAF or RET/PTC), through a mechanism that involves the actin cytoskeleton but not an increased capacity of matrix degradation.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-016-2146-z) contains supplementary material, which is available to authorized users.