Upregulation of miR-27a contributes to the malignant transformation of human bronchial epithelial cells induced by SV40 small T antigen

Molecular insights and clinical implications for the tumor suppressor role of SCFFBXW7 E3 ubiquitin ligase

FBXW7 is one of the most well-characterized F-box proteins, serving as substrate receptor subunit of SKP1-CUL1-F-box (SCF) E3 ligase complexes. SCFFBXW7 is responsible for the degradation of various oncogenic proteins such as cyclin E, c-MYC, c-JUN, NOTCH, and MCL1. Therefore, FBXW7 functions largely as a major tumor suppressor. In keeping with this notion, FBXW7 gene mutations or downregulations have been found and reported in many types of malignant tumors, such as endometrial, colorectal, lung, and breast cancers, which facilitate the proliferation, invasion, migration, and drug resistance of cancer cells. Therefore, it is critical to review newly identified FBXW7 regulation and tumor suppressor function under physiological and pathological conditions to develop effective strategies for the treatment of FBXW7-altered cancers. Since a growing body of evidence has revealed the tumor-suppressive activity and role of FBXW7, here, we updated FBXW7 upstream and downstream signaling including FBXW7 ubiquitin substrates, the multi-level FBXW7 regulatory mechanisms, and dysregulation of FBXW7 in cancer, and discussed promising cancer therapies targeting FBXW7 regulators and downstream effectors, to provide a comprehensive picture of FBXW7 and facilitate the study in this field.

Protein phosphatase 2A modulation and connection with miRNAs and natural products

Protein phosphatase 2A (PP2A), a heterotrimeric holoenzyme (scaffolding, catalytic, and regulatory subunits), regulates dephosphorylation for more than half of serine/threonine phosphosites and exhibits diverse cellular functions. Although several studies on natural products and miRNAs have emphasized their impacts on PP2A regulation, their connections lack systemic organization. Moreover, only part of the PP2A family has been investigated. This review focuses on the PP2A-modulating effects of natural products and miRNAs' interactions with potential PP2A targets in cancer and non-cancer cells. PP2A-modulating natural products and miRNAs were retrieved through a literature search. Utilizing the miRDB database, potential PP2A targets of these PP2A-modulating miRNAs for the whole set (17 members) of the PP2A family were retrieved. Finally, PP2A-modulating natural products and miRNAs were linked via a literature search. This review provides systemic directions for assessing natural products and miRNAs relating to the PP2A-modulating functions in cancer and disease treatments.

Inhibitors Targeting the F-BOX Proteins

F-box proteins are involved in multiple cellular processes through ubiquitylation and consequent degradation of targeted substrates. Any significant mutation in F-box protein-mediated proteolysis can cause human malformations. The various cellular processes F-box proteins involved include cell proliferation, apoptosis, invasion, angiogenesis, and metastasis. To target F-box proteins and their associated signaling pathways for cancer treatment, researchers have developed thousands of F-box inhibitors. The most advanced inhibitor of FBW7, NVD-BK M120, is a powerful P13 kinase inhibitor that has been proven to bring about apoptosis in cancerous human lung cells by disrupting levels of the protein known as MCL1. Moreover, F-box Inhibitors have demonstrated their efficacy for treating certain cancers through targeting particular mutated proteins. This paper explores the key studies on how F-box proteins act and their contribution to malignancy development, which fabricates an in-depth perception of inhibitors targeting the F-box proteins and their signaling pathways that eventually isolate the most promising approach to anti-cancer treatments.

MiRNA-related metastasis in oral cancer: moving and shaking

Across the world, oral cancer is a prevalent tumor. Over the years, both its mortality and incidence have grown. Oral cancer metastasis is a complex process involving cell invasion, migration, proliferation, and egress from cancer tissue either by lymphatic vessels or blood vessels. MicroRNAs (miRNAs) are essential short non-coding RNAs, which can act either as tumor suppressors or as oncogenes to control cancer development. Cancer metastasis is a multi-step process, in which miRNAs can inhibit or stimulate metastasis at all stages, including epithelial-mesenchymal transition, migration, invasion, and colonization, by targeting critical genes in these pathways. On the other hand, long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs), two different types of non-coding RNAs, can regulate cancer metastasis by affecting gene expression through cross-talk with miRNAs. We reviewed the scientific literature (Google Scholar, Scopus, and PubMed) for the period 2000-2023 to find reports concerning miRNAs and lncRNA/circRNA-miRNA-mRNA networks, which control the spread of oral cancer cells by affecting invasion, migration, and metastasis. According to these reports, miRNAs are involved in the regulation of metastasis pathways either by directly or indirectly targeting genes associated with metastasis. Moreover, circRNAs and lncRNAs can induce or suppress oral cancer metastasis by acting as competing endogenous RNAs to inhibit the effect of miRNA suppression on specific mRNAs. Overall, non-coding RNAs (especially miRNAs) could help to create innovative therapeutic methods for the control of oral cancer metastases.

Epigenetic regulation of stem cells in lung cancer oncogenesis and therapy resistance

Epigenetics plays an important role in regulating stem cell signaling, as well as in the oncogenesis of lung cancer and therapeutic resistance. Determining how to employ these regulatory mechanisms to treat cancer is an intriguing medical challenge. Lung cancer is caused by signals that cause aberrant differentiation of stem cells or progenitor cells. The different pathological subtypes of lung cancer are determined by the cells of origin. Additionally, emerging studies have demonstrated that the occurrence of cancer treatment resistance is connected to the hijacking of normal stem cell capability by lung cancer stem cells, especially in the processes of drug transport, DNA damage repair, and niche protection. In this review, we summarize the principles of the epigenetic regulation of stem cell signaling in relation to the emergence of lung cancer and resistance to therapy. Furthermore, several investigations have shown that the tumor immune microenvironment in lung cancer affects these regulatory pathways. And ongoing experiments on epigenetics-related therapeutic strategies provide new insight for the treatment of lung cancer in the future.

Clinical significance of FBXW7 loss of function in human cancers

FBXW7 (F-Box and WD Repeat Domain Containing 7) (also referred to as FBW7 or hCDC4) is a component of the Skp1-Cdc53 / Cullin-F-box-protein complex (SCF/β-TrCP). As a member of the F-box protein family, FBXW7 serves a role in phosphorylation-dependent ubiquitination and proteasome degradation of oncoproteins that play critical role(s) in oncogenesis. FBXW7 affects many regulatory functions involved in cell survival, cell proliferation, tumor invasion, DNA damage repair, genomic instability and telomere biology. This thorough review of current literature details how FBXW7 expression and functions are regulated through multiple mechanisms and how that ultimately drives tumorigenesis in a wide array of cell types. The clinical significance of FBXW7 is highlighted by the fact that FBXW7 is frequently inactivated in human lung, colon, and hematopoietic cancers. The loss of FBXW7 can serve as an independent prognostic marker and is significantly correlated with the resistance of tumor cells to chemotherapeutic agents and poorer disease outcomes. Recent evidence shows that genetic mutation of FBXW7 differentially affects the degradation of specific cellular targets resulting in a distinct and specific pattern of activation/inactivation of cell signaling pathways. The clinical significance of FBXW7 mutations in the context of tumor development, progression, and resistance to therapies as well as opportunities for targeted therapies is discussed.

Endotoxin stabilizes protein arginine methyltransferase 4 (PRMT4) protein triggering death of lung epithelia

Lung epithelial cell death is a prominent feature of acute lung injury and acute respiratory distress syndrome (ALI/ARDS), which results from severe pulmonary infection leading to respiratory failure. Multiple mechanisms are believed to contribute to the death of epithelia; however, limited data propose a role for epigenetic modifiers. In this study, we report that a chromatin modulator protein arginine N-methyltransferase 4/coactivator-associated arginine methyltransferase 1 (PRMT4/CARM1) is elevated in human lung tissues with pneumonia and in experimental lung injury models. Here PRMT4 is normally targeted for its degradation by an E3 ubiquitin ligase, SCF^FBXO9, that interacts with PRMT4 via a phosphodegron to ubiquitinate the chromatin modulator at K228 leading to its proteasomal degradation. Bacterial-derived endotoxin reduced levels of SCF^FBXO9 thus increasing PRMT4 cellular concentrations linked to epithelial cell death. Elevated PRMT4 protein caused substantial epithelial cell death via caspase 3-mediated cell death signaling, and depletion of PRMT4 abolished LPS-mediated epithelial cell death both in cellular and murine injury models. These findings implicate a unique molecular interaction between SCF^FBXO9 and PRMT4 and its regulation by endotoxin that impacts the life span of lung epithelia, which may play a key role in the pathobiology of tissue injury observed during critical respiratory illness.

FBXW7 induces apoptosis in glioblastoma cells by regulating HDAC7

Glioblastoma is an aggressive type of brain cancer with an extremely poor prognosis. Additionally, the F-box WD repeat-containing protein 7 (FBXW7) is a component of the ubiquitin-proteasome system that has been widely implicated in human cancers. In this study, we investigated the role and mechanism of FBXW7 in glioblastoma. FBXW7 expression was analyzed in normal and glioblastoma tissue samples using The Cancer Genome Atlas Glioblastoma Multiforme (TCGA-GBM) database. Then, quantitative reverse transcription-polymerase chain reaction (RT-PCR) was used to examine mRNA expression, whereas, western blot analysis was conducted to determine protein levels of the samples. Furthermore, cell apoptosis was assessed using the Annexin V staining method, followed by flow cytometry analysis. Immunoprecipitation (IP) assay was conducted as well to test protein-protein interactions. Lastly, protein expression in tissues was examined by conducting immunohistochemistry (IHC). Results showed that the glioblastoma tissue samples displayed an FBXW7 downregulation compared with normal tissues. In vitro, the overexpression of FBXW7 in glioblastoma cells induced apoptosis, whereas, its knockdown displayed the opposite effect. Mechanistically, FBXW7 interacted with HDAC7 to promote HDAC7 ubiquitination, however, the overexpression of HDAC7 in glioblastoma cells blocked FBXW7-induced apoptosis. Finally, FBXW7 and HDAC7 displayed an inverse correlation in glioblastoma tissues in vivo. Therefore, our data demonstrated an important function of FBXW7 in promoting glioblastoma apoptosis by interacting with HDAC7 and promoting HDAC7 ubiquitination.

The impact of microRNAs on myeloid-derived suppressor cells in cancer

Inflammation promotes cancer development. To a large extent, this can be attributed to the recruitment of myeloid-derived suppressor cells (MDSCs) to tumors. These cells are known for establishing an immunosuppressive tumor microenvironment by suppressing T cell activities. However, MDSCs also promote metastasis and angiogenesis. Critically, as small non-coding RNAs that regulate gene expression, microRNAs (miRNAs) control MDSC activities. In this review, we discuss how miRNA networks regulate key MDSC signaling pathways, how they shape MDSC development, differentiation and activation, and how this impacts tumor development. By targeting the expression of miRNAs in MDSCs, we can alter their main signaling pathways. In turn, this can compromise their ability to promote multiple hallmarks of cancer. Therefore, this may represent a new powerful strategy for cancer immunotherapy.

The FBXW7-NOTCH interactome: A ubiquitin proteasomal system-induced crosstalk modulating oncogenic transformation in human tissues

BACKGROUND

Ubiquitin ligases or E3 ligases are well programmed to regulate molecular interactions that operate at a post-translational level. Skp, Cullin, F-box containing complex (or SCF complex) is a multidomain E3 ligase known to mediate the degradation of a wide range of proteins through the proteasomal pathway. The three-dimensional domain architecture of SCF family proteins suggests that it operates through a novel and adaptable "super-enzymatic" process that might respond to targeted therapeutic modalities in cancer.

RECENT FINDINGS

Several F-box containing proteins have been characterized either as tumor suppressors (FBXW8, FBXL3, FBXW8, FBXL3, FBXO1, FBXO4, and FBXO18) or as oncogenes (FBXO5, FBXO9, and SKP2). Besides, F-box members like βTrcP1 and βTrcP2, the ones with context-dependent functionality, have also been studied and reported. FBXW7 is a well-studied F-box protein and is a tumor suppressor. FBXW7 regulates the activity of a range of substrates, such as c-Myc, cyclin E, mTOR, c-Jun, NOTCH, myeloid cell leukemia sequence-1 (MCL1), AURKA, NOTCH through the well-known ubiquitin-proteasome system (UPS)-mediated degradation pathway. NOTCH signaling is a primitive pathway that plays a crucial role in maintaining normal tissue homeostasis. FBXW7 regulates NOTCH protein activity by controlling its half-life, thereby maintaining optimum protein levels in tissue. However, aberrations in the FBXW7 or NOTCH expression levels can lead to poor prognosis and detrimental outcomes in patients. Therefore, the FBXW7-NOTCH axis has been a subject of intense study and research over the years, especially around the interactome's role in driving cancer development and progression. Several studies have reported the effect of FBXW7 and NOTCH mutations on normal tissue behavior. The current review attempts to critically analyze these mutations prognostic value in a wide range of tumors. Furthermore, the review summarizes the recent findings pertaining to the FBXW7 and NOTCH interactome and its involvement in phosphorylation-related events, cell cycle, proliferation, apoptosis, and metastasis.

CONCLUSION

The review concludes by positioning FBXW7 as an effective diagnostic marker in tumors and by listing out recent advancements made in cancer therapeutics in identifying protocols targeting the FBXW7-NOTCH aberrations in tumors.

Cigarette Smoke Extract induces H19 in Esophageal Squamous Cell Carcinoma in Smoking Patients: Based on A Chronic Exposed Cell Model

Cigarette smoking is a factor capable of inducing esophageal squamous cell carcinoma (ESCC). However, the biological pathways that are responsible for tumor development and are directly affected by cigarette smoking remain unknown. To explore the role of cigarette smoking in ESCC, we developed a long-term cigarette smoke extract (CSE) exposed cell model using the normal immortalized SHEE esophageal epithelial cell line, which would malignantly transform after long-term cultivation without carcinogens. CSE-exposed cells displayed higher malignancy and differently expressed several lncRNAs. Among them, H19, a lncRNA responsible for proliferation and invasion, was upregulated in CSE-exposed SHEE cells. In tumors from ESCC patients, H19 was significantly increased in smoking ESCC patients compared to non-smoking patients, and H19 was overexpressed and correlated with pathological tumor size in smokers. These results indicated that cigarette smoking lead to a different biological change from non-smoking induced ESCC and H19 related to cancer development during CSE-induced carcinogenesis.

Function and regulation of F-box/WD repeat-containing protein 7

The ubiquitin-proteasome system is an important post-translational modification system involved in numerous biological processes, such as cell cycle regulation, gene transcription, signal transduction, apoptosis, differentiation and development. F-box/WD repeat-containing protein 7 (FBXW7) is one of the most studied F-box (FBX) proteins, serving as substrate recognition component of S phase kinase-associated protein 1-Cullin 1-FBX protein complexes. As a tumor suppressor, FBXW7 recognizes numerous proto-oncoproteins and promotes their ubiquitination and subsequent proteasomal degradation. FBXW7 is regulated at different levels, leading to tunable and specific control of the activity and abundance of its substrates. Therefore, genetic mutations or decreases in its expression serve an important biological role in tumor development. In-depth studies and identification of additional substrates targeted by FBXW7 have suggested a signaling network regulated by FBXW7, including its tumor-inhibitory role. The present review focused on the role of FBXW7 in tumor suppression and its application in cancer therapy.

RASA1 inhibits the progression of renal cell carcinoma by decreasing the expression of miR-223-3p and promoting the expression of FBXW7

RAS p21 protein activator 1 (RASA1), also known as p120-RasGAP, is a RasGAP protein that functions as a signaling scaffold protein, regulating pivotal signal cascades. However, its biological mechanism in renal cell carcinoma (RCC) remains unknown. In the present study, RASA1, F-box/WD repeat-containing protein 7 (FBXW7), and miR-223-3p expression were assessed via quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and Western blot. Then, the targeted correlations of miR-223-3p with FBXW7 and RASA1 were verified via a dual-luciferase reporter gene assay. CCK-8, flow cytometry, and Transwell assays were implemented independently to explore the impact of RASA1 on cell proliferation, apoptosis, migration, and cell cycle progression. Finally, the influence of RASA1 on tumor formation in RCC was assessed in vivo through the analysis of tumor growth in nude mice. Results showed that FBXW7 and RASA1 expression were decreased in RCC tissues and cell lines, while miR-223-3p was expressed at a higher level. Additionally, FBXW7 and RASA1 inhibited cell proliferation but facilitated the population of RCC cells in the G0/G1 phase. Altogether, RASA1 may play a key role in the progression of RCC by decreasing miR-223-3p and subsequently increasing FBXW7 expression.

CTBP1‑AS2 inhibits proliferation and induces autophagy in ox‑LDL‑stimulated vascular smooth muscle cells by regulating miR‑195‑5p/ATG14

Atherosclerosis (AS) is a chronic progressive disease caused by injury and functional changes in vascular smooth muscle cells (VSMCs). Long non‑coding RNAs (lncRNAs) are pivotal regulators in AS development. The present study aimed to explore the roles and molecular mechanisms of lncRNA CTBP1‑AS2 in AS progression. A dual‑luciferase reporter assay confirmed that miR‑195‑5p is a downstream target miRNA of lncRNA CTBP1‑AS2 and miR‑195‑5p was increased in AS. The expression levels of miR‑195‑5p and CTBP1‑AS2 in the serums of patients with AS and human aorta vascular smooth muscle cells was increased or decreased, respectively, following treatment with oxidized low‑density lipoprotein (ox‑LDL). Functional experiments showed that the overexpression of lncRNA CTBP1‑AS2 inhibited the proliferation of HA‑VSMCs and promoted their autophagy following ox‑LDL treatment. This effect could be reversed by treatment with ROC‑325, the inhibitor of autophagy, or miR‑195‑5p mimics. Autophagy related 14 (ATG14) was identified to be a target of miR‑195‑5p, and lncRNA CTBP1‑AS2 promoted ATG14 expression by serving as a competing endogenous RNA of miR‑195‑5p. The present study revealed that lncRNA CTBP1‑AS2 may serve a role in AS by inhibiting the proliferation and promoting the autophagy of VSMCs through ATG14 modulation via miR‑195‑5p. These data may provide a novel therapeutic target for AS.

Non-Coding RNAs in Lung Tumor Initiation and Progression

Lung cancer is one of the deadliest forms of cancer affecting society today. Non-coding RNAs, such as microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs), through the transcriptional, post-transcriptional, and epigenetic changes they impose, have been found to be dysregulated to affect lung cancer tumorigenesis and metastasis. This review will briefly summarize hallmarks involved in lung cancer initiation and progression. For initiation, these hallmarks include tumor initiating cells, immortalization, activation of oncogenes and inactivation of tumor suppressors. Hallmarks involved in lung cancer progression include metastasis and drug tolerance and resistance. The targeting of these hallmarks with non-coding RNAs can affect vital metabolic and cell signaling pathways, which as a result can potentially have a role in cancerous and pathological processes. By further understanding non-coding RNAs, researchers can work towards diagnoses and treatments to improve early detection and clinical response.

Recent insight into the role of FBXW7 as a tumor suppressor

FBXW7 (also known as Fbw7, Sel10, hCDC4, or hAgo) is a tumor suppressor and the most frequently mutated member of the F-box protein family in human cancers. FBXW7 functions as the substrate recognition component of an SCF-type E3 ubiquitin ligase. It specifically controls the proteasome-mediated degradation of many oncoproteins such as c-MYC, NOTCH, KLF5, cyclin E, c-JUN, and MCL1. In this review, we summarize the molecular and biological features of FBXW7 and its substrates as well as the impact of mutations of FBXW7 on cancer development. We also address the clinical potential of anticancer therapy targeting FBXW7.

MiR-223 promotes oral squamous cell carcinoma proliferation and migration by regulating FBXW7

Abnormally expressed microRNAs (miRNAs) contribute widely to human cancer, including oral squamous cell carcinoma (OSCC), by regulating their downstream targets. MiR-223 has been proved to be up-regulated in both gastric cancer and ovarian cancer. However, the effect of miR-223 on OSCC is still unclear. Here, we showed that miR-223 was over-expressed in OSCC tissues using qRT-PCR. Next, we investigated the biological mechanism of miR-223 in OSCC. The results demonstrated that miR-223 facilitated the cell proliferation and migration of OSCC using MTT assay and Transwell assay. Furthermore, we stated that the FBXW7 expression was decreased in OSCC and re-expression of FBXW7 inhibited the proliferation and migration of OSCC. In addition, FBXW7 mimic inversed the promotion effect of miR-223 in regulating of OSCC cells. In short, miR-223 promoted OSCC cell proliferation and migration by downregulating FBXW7, which provided a novel therapeutic strategy for OSCC.

MiR-27a: A Novel Biomarker and Potential Therapeutic Target in Tumors

MicroRNAs (miRNAs) are endogenous, time sequencing, conserved and small non-coding RNA molecules (19-25 bp long) that regulate gene expression at the post-transcriptional level by binding to the partial sequence homology of the 3'-untranslated region of target messenger (m)RNA. The miRNA-27 family consists of miR-27a and miR-27b, which are transcribed from different chromosomes and different in nucleotide at the 3' end. It has been reported that miR-27a was located on chromosome 19 and played a vital role in tumor development. Increasing evidences support a vital role for miR-27a in modulating polymorphisms, tumorigenesis, proliferation, apoptosis, invasion, migration and angiogenesis. Apart from it, miR-27a could affect drug sensitivity, treatment of cancer and patients prognosis. The miR-27a could be an oncogene or a tumor suppressor in several types of cancer, including colon cancer, pancreatic cancer, breast cancer, bladder cancer and hepatocellular carcinoma. In this review, we discuss the role of miR-27a in tumor biology and clinical significance in detail and offer novel insights into molecular targeting therapy for human cancers.

Persistence of smoking induced non-small cell lung carcinogenesis by decreasing ERBB pathway-related microRNA expression

Background

Tobacco use is responsible for approximately 80–90% of non‐small cell lung cancer cases. A large evidence base has shown that the ERBB pathway is associated with the occurrence of lung cancer. However, the mechanisms of how smoking activates the ERBB pathway have yet to be explained. We hypothesized that microRNAs may induce ERBB pathway activity during the process of lung cancer carcinogenesis.

Methods

We analyzed microRNA array data from the Gene Expression Omnibus and the Kyoto Encyclopedia of Genes and Genomes to determine any associations between genes and smoking in three groups of patients with NSCLC: smokers, former smokers, and non‐smokers.

Results

The interaction network among miRNAs, including hsa‐mir‐185‐3p, hsa‐mir‐4295, hsa‐mir‐4288, and hsa‐mir‐613, promotes lung cancer development by affecting the ERBB pathway.

Conclusion

Our findings provide evidence to explain the mechanism of lung cancer development in smokers.

Regulation of the phosphoprotein phosphatase 2A system and its modulation during oxidative stress: A potential therapeutic target?

Phosphoprotein phosphatases are of growing interest in the pathophysiology of many diseases and are often the neglected partner of protein kinases. One family member, PP2A, accounts for dephosphorylation of ~55-70% of all serine/threonine phosphosites. Interestingly, dysregulation of kinase signalling is a hallmark of many diseases in which an increase in oxidative stress is also noted. With this in mind, we assess the evidence to support oxidative stress-mediated regulation of the PP2A system In this article, we first present an overview of the PP2A system before providing an analysis of the regulation of PP2A by endogenous inhibitors, post translational modification, and miRNA. Next, a detailed critique of data implicating reactive oxygen species, ischaemia, ischaemia-reperfusion, and hypoxia in regulating the PP2A holoenzyme and associated regulators is presented. Finally, the pharmacological targeting of PP2A, its endogenous inhibitors, and enzymes responsible for its post-translational modification are covered. There is extensive evidence that oxidative stress modulates multiple components of the PP2A system, however, most of the data pertains to the catalytic subunit of PP2A. Irrespective of the underlying aetiology, free radical-mediated attenuation of PP2A activity is an emerging theme. However, in many instances, a dichotomy exists, which requires clarification and mechanistic insight. Nevertheless, this raises the possibility that pharmacological activation of PP2A, either through small molecule activators of PP2A or CIP2A/SET antagonists may be beneficial in modulating the cellular response to oxidative stress. A better understanding of which, will have wide ranging implications for cancer, heart disease and inflammatory conditions.

FBXW7 in Cancer: What Has Been Unraveled Thus Far?

: The FBXW7 (F-box with 7 tandem WD40) protein encoded by the gene FBXW7 is one of the crucial components of ubiquitin ligase called Skp1-Cullin1-F-box (SCF) complex that aids in the degradation of many oncoproteins via the ubiquitin-proteasome system (UPS) thus regulating cellular growth. FBXW7 is considered as a potent tumor suppressor as most of its target substrates can function as potential growth promoters, including c-Myc, Notch, cyclin E, c-JUN, and KLF5. Its regulators include p53, C/EBP-δ, Numb, microRNAs, Pin 1, Hes-5, BMI1, Ebp2. Mounting evidence has indicated the involvement of aberrant expression of FBXW7 for tumorigenesis. Moreover, numerous studies have also shown its role in cancer cell chemosensitization, thereby demonstrating the importance of FBXW7 in the development of curative cancer therapy. This comprehensive review emphasizes on the targets, functions, regulators and expression of FBXW7 in different cancers and its involvement in sensitizing cancer cells to chemotherapeutic drugs.

The Diverse Roles of microRNAs at the Host⁻Virus Interface

MicroRNAs (miRNAs) are small, non-coding RNAs that regulate gene expression at the post-transcriptional level. Through this activity, they are implicated in almost every cellular process investigated to date. Hence, it is not surprising that miRNAs play diverse roles in regulation of viral infections and antiviral responses. Diverse families of DNA and RNA viruses have been shown to take advantage of cellular miRNAs or produce virally encoded miRNAs that alter host or viral gene expression. MiRNA-mediated changes in gene expression have been demonstrated to modulate viral replication, antiviral immune responses, viral latency, and pathogenesis. Interestingly, viruses mediate both canonical and non-canonical interactions with miRNAs to downregulate specific targets or to promote viral genome stability, translation, and/or RNA accumulation. In this review, we focus on recent findings elucidating several key mechanisms employed by diverse virus families, with a focus on miRNAs at the host–virus interface during herpesvirus, polyomavirus, retroviruses, pestivirus, and hepacivirus infections.

miR-27a induced by colon cancer cells in HLECs promotes lymphangiogenesis by targeting SMAD4

Aim

Metastasis of tumor cells occurs through lymphatic vessels, blood vessels and transcoelomic spreading. Growing evidence from in vivo and in vitro studies has indicated that tumor lymphangiogenesis facilitates metastasis. However, the regulation of lymphangiogenesis in colon cancer remains unclear. The aims of this study were to identify key miRNAs in colon cancer lymphangiogenesis and to investigate its target and mechanism.

Methods

miRNA microarray analysis was conducted to identify miRNAs in human lymphatic endothelial cells (HLECs) that were regulated by co-cultured human colon cancer cells. Gain- and loss-of-function studies were performed to determine the function of miR-27a, a top hint, on lymphangiogenesis and migration in HLECs. Furthermore, bioinformatics prediction and experimental validation were performed to identify miR-27a target genes in lymphangiogenesis.

Results

We found that expression of miR-27a in HLECs was induced by co-culturing with colon cancer cells. Over-expression of miR-27a in HLECs enhanced lymphatic tube formation and migration, whereas inhibition of miR-27a reduced lymphatic tube formation and migration. Luciferase reporter assays showed that miR-27a directly targeted SMAD4, a pivotal component of the TGF-β pathway. In addition, gain-of-function and loss-of-function experiments showed that SMAD4 negatively regulated the length of lymphatic vessels formed by HLECs and migration.

Conclusions

Our data indicated that colon cancer cell induced the expression of miR-27a in HLECs, which promoted lymphangiogenesis by targeting SMAD4. Our finding implicated miR-27a as a potential target for new anticancer therapies in colon cancer.

Serum MicroRNA-150 Predicts Prognosis for Early-Stage Non-Small Cell Lung Cancer and Promotes Tumor Cell Proliferation by Targeting Tumor Suppressor Gene SRCIN1

This integrative multistage study was aimed to identify circulating microRNAs (miRNAs) as prognostic biomarkers and investigate the treatment target for early-stage non-small cell lung cancer (NSCLC) patients. In stage I-II NSCLC patients, we screened and validated the miRNA ratio signatures predictive of prognosis in serum. In tumor, we found that the expression of miR-150 in identified miRNA signatures was also associated with survival. Increased miR-150 expression promoted NSCLC cell proliferation and migration and vice versa. Specific mRNA cleavage sites targeted by endogenous miR-150 in 3' untranslated region (UTR) of SRCIN1 was identified by utilizing our recently developed novel Stem-Loop-Array reverse-transcription polymerase chain reaction (SLA-RT-PCR) assay. The blocking action of miR-150 resulted in repressed NSCLC cell growth in vitro and knockdown of miR-150 caused substantial tumor volume reduction in vivo. Our findings suggest that miR-150 binding on specific recognition sites in 3' UTR of tumor suppressor gene SRCIN1 present a potential therapeutic target for NSCLC.

TRIM36 hypermethylation is involved in polycyclic aromatic hydrocarbons-induced cell transformation

Long term exposure to polycyclic aromatic hydrocarbons (PAHs) is associated with the increasing risk of lung cancer. To identify differentially hypermethylated genes associated with PAHs-induced carcinogenicity, we performed genome-wide DNA methylation analysis in 20 μM benzo(a)pyrene (BaP)-transformed human bronchial epithelial (HBE) cells at different stages of cell transformation. Several methylated genes (CNGA4, FLT1, GAREM1, SFMBT2, TRIM36) were differentially hypermethylated and their mRNA was suppressed in cells at both pre-transformed and transformed stages. Similar results were observed in HBE cells transformed by 20 μg/mL coke oven emissions (COEs) mixture collected from a coking manufacturing facility. In particular, hypermethylation of TRIM36 and suppression of TRIM36 expression were gradually enhanced over the time of COEs treatment. We developed bisulfite pyrosequencing assay and assessed TRIM36 methylation quantitatively. We found that hypermethylation of TRIM36 and reduced gene expression was prevalent in several types of human cancers. TRIM36 hypermethylation appeared in 90.0% (23/30) of Non-Small Cell Lung Cancer (NSCLCs) tissues compared to their paired adjacent tissues with an average increase of 1.32 fold. Furthermore, an increased methylation rate (5.90% v.s 7.38%) and reduced levels of TRIM36 mRNA were found in peripheral lymphocytes (PBLCs) of 151 COEs-exposed workers. In all subjects, TRIM36 hypermethylation was positively correlated with the level of urinary 1-hydroxypyrene (P < 0.001), an internal exposure marker of PAHs, and the DNA damage (P = 0.013). These findings suggest that aberrant hypermethylation of TRIM36 might be involved in the acquisition of malignant phenotype and could be served as a biomarker for risk assessment of PAHs exposure.

Smoker extracellular vesicles influence status of human bronchial epithelial cells

Cigarette smoking is a habit that has spread all over the world and is a significant risk factor for many diseases including cardiovascular disease, chronic obstructive pulmonary disease (COPD), asthma and lung cancer. Evaluation and understanding of tobacco health effects are of major interest worldwide and answer to important societal concerns. Identification of new biomarkers of exposure to tobacco smoke potentially implicated in COPD or lung carcinogenesis would allow a better observation of tobacco exposed population, thanks to screening establishment at reversible stages of pathological processes. In this study, we questioned whether cigarette smoking alters miRNA profiles of Extracellular Vesicles (EVs) present in human Broncho Alveolar Lavages (BALs), which could affect surrounding normal bronchial epithelial cells status. To this aim, BALs were carried out on 10 Smokers and 10 Non-Smokers, and EVs were isolated from the supernatants and characterized. We then compared the amount of 10 microRNAs (miRNAs) present in Smokers versus Non-Smokers BAL EVs and performed statistical analysis to discuss the biological significance by the smoking status and to evaluate BAL EV miRNAs as potential biomarkers of tobacco exposure. Finally, we tested the effects of smokers versus non-smokers EVs on human bronchial epithelial cells (BEAS-2B) to compare their influence on the cells status. Our study shows for the first time in human samples that smoking can alter lung EV profile that can influence surrounding bronchial epithelial cells.

microRNA-25 Inhibits Cell Apoptosis of Human Gastric Adenocarcinoma Cell Line AGS via Regulating CCNE1 and MYC

BACKGROUND Gastric carcinoma is the second leading cause of cancer death. microRNAs play vital roles in regulating expression of related oncogenes. microRNA-25 (miR-25) has been found to be up-regulated in gastric carcinoma. However, its roles in affecting cell apoptosis of gastric carcinoma and the related mechanism remain elusive. This study aimed to uncover the influences of miR-25 on gastric carcinoma cell apoptosis and the possible functional mechanisms involved. MATERIAL AND METHODS Human gastric adenocarcinoma cell line AGS was used and transfected with lentivirus containing miR-25-specifc inhibitor sponge or expression vector to analyze the effects of miR-25. RESULTS miR-25 had higher expression in AGS than in human gastric epithelial cell line GES-1 (P<0.01). Inhibition of miR-25 by its sponge in AGS cells resulted in suppressed cell viability (P<0.01) and promoted cell apoptosis (P<0.01), while overexpression of miR-25 abrogated these effects (P<0.01 and P<0.05), indicating that miR-25 can promote cell viability and inhibit cell apoptosis in AGS cells. Expression analysis of related factors by Western blot showed that inhibiting miR-25 led to the up-regulation of F-box and WD repeat domain-containing 7 (FBXW7, P<0.01) and the down-regulation of FBXW7 substrates, cyclin E1 (CCNE1, P<0.01), and v-myc avian myelocytomatosis viral oncogene homolog (MYC, P<0.001). CONCLUSIONS These results indicate that miR-25 has anti-apoptosis roles in AGS cells, possibly via inhibiting FBXW7 and thus promoting oncogenes, such as CCNE1 and MYC. This study provides basic evidence for using miR-25 as a possible therapeutic target in treating gastric carcinoma.

MiR-27a regulates Wnt/beta-catenin signaling through targeting SFRP1 in glioma

Glioma is one of the most common intracranial tumors, and the prognosis is poor, although more and more treatments are employed. Wnt/beta-catenin signaling has been reported to be associated with glioma. SFRP1 acts as an antagonist and inhibits Wnt signaling by binding to Wnt molecules. In the present study, we aimed to investigate miRNA-27a as an antineoplastic factor that inhibits the Wnt/beta-catenin pathway by binding to the SFRP1 3'-UTR in glioma in vitro. We first showed that the expression of miR-27a was elevated in both glioma samples and cell lines. Furthermore, downregulation of miR-27a induced growth inhibition, cycle arrest, and apoptosis, and suppressed invasion/migration in glioma cell lines. Quantitative real-time PCR, western blot, and luciferase assay analysis showed that SFRP1 is a direct target of miR-27a. Overexpression of SFRP1 inhibited the malignancy of glioma cell lines. Our investigation showed that downregulation of miR-27a suppressed beta-catenin/TCF-4 transcription activity by targeting SFRP1. Our findings identify a role for miR-27a in glioma cell viability, cycle, apoptosis, and invasion/migration after activation of Wnt/beta-catenin signaling through SFRP1.

MicroRNAs 24 and 27 Suppress Allergic Inflammation and Target a Network of Regulators of T Helper 2 Cell-Associated Cytokine Production

MicroRNAs (miRNAs) are important regulators of cell fate decisions in immune responses. They act by coordinate repression of multiple target genes, a property that we exploited to uncover regulatory networks that govern T helper-2 (Th2) cells. A functional screen of individual miRNAs in primary T cells uncovered multiple miRNAs that inhibited Th2 cell differentiation. Among these were miR-24 and miR-27, miRNAs coexpressed from two genomic clusters, which each functioned independently to limit interleukin-4 (IL-4) production. Mice lacking both clusters in T cells displayed increased Th2 cell responses and tissue pathology in a mouse model of asthma. Gene expression and pathway analyses placed miR-27 upstream of genes known to regulate Th2 cells. They also identified targets not previously associated with Th2 cell biology which regulated IL-4 production in unbiased functional testing. Thus, elucidating the biological function and target repertoire of miR-24 and miR-27 reveals regulators of Th2 cell biology.

Early and late effects of prenatal corticosteroid treatment on the microRNA profiles of lung tissue in rats

Glucocorticoids have been administered to mothers at risk of premature delivery to induce maturation of preterm fetal lungs and prevent the development of respiratory distress syndrome. Micro (mi)RNAs serve various crucial functions in cell proliferation, differentiation and organ development; however, few studies have demonstrated an association between miRNAs and lung development. The aim of the present study was to investigate alterations in the miRNA profiles of rat lung tissue following prenatal glucocorticoid therapy for fetal lung development. The differences in miRNA expression profiles were compared between postnatal days 7 (D7) and 120 (D120) rat lung tissues, followed by validation using reverse transcription-quantitative polymerase chain reaction. The miRNA profiles of rat lung tissues following prenatal dexamethasone (DEX) therapy were also investigated. miRNAs with 2-fold changes were selected for further analysis. At D120, 6 upregulated and 6 downregulated miRNAs were detected, compared with D7. Among these differentially expressed miRNAs, miR-101-3p and miR-99b-5p were associated with the lowest and highest expressions of miRNA at D7, respectively. A limited impact on the miRNA profiles of rat lung tissues was observed following prenatal DEX treatment, which may help to further clarify the mechanisms underlying normal lung development. However, the results of the present study cannot entirely elucidate the effects of prenatal DEX treatment on the lung development of premature infants, and further studies investigating the impact of prenatal corticosteroids on fetal lung miRNA profiles are required.

mRNAs and miRNAs in whole blood associated with lung hyperplasia, fibrosis, and bronchiolo-alveolar adenoma and adenocarcinoma after multi-walled carbon nanotube inhalation exposure in mice

Inhalation exposure to multi-walled carbon nanotubes (MWCNT) in mice results in inflammation, fibrosis and the promotion of lung adenocarcinoma; however, the molecular basis behind these pathologies is unknown. This study determined global mRNA and miRNA profiles in whole blood from mice exposed by inhalation to MWCNT that correlated with the presence of lung hyperplasia, fibrosis, and bronchiolo-alveolar adenoma and adenocarcinoma. Six-week-old, male, B6C3F1 mice received a single intraperitoneal injection of either the DNA-damaging agent methylcholanthrene (MCA, 10 µg g(-1) body weight) or vehicle (corn oil). One week after injections, mice were exposed by inhalation to MWCNT (5 mg m(-3), 5 hours per day, 5 days per week) or filtered air (control) for a total of 15 days. At 17 months post-exposure, mice were euthanized and examined for the development of pathological changes in the lung, and whole blood was collected and analyzed using microarray analysis for global mRNA and miRNA expression. Numerous mRNAs and miRNAs in the blood were significantly up- or down-regulated in animals developing pathological changes in the lung after MCA/corn oil administration followed by MWCNT/air inhalation, including fcrl5 and miR-122-5p in the presence of hyperplasia, mthfd2 and miR-206-3p in the presence of fibrosis, fam178a and miR-130a-3p in the presence of bronchiolo-alveolar adenoma, and il7r and miR-210-3p in the presence of bronchiolo-alveolar adenocarcinoma, among others. The changes in miRNA and mRNA expression, and their respective regulatory networks, identified in this study may potentially serve as blood biomarkers for MWCNT-induced lung pathological changes.

Rs895819 within miR-27a might be involved in development of non small cell lung cancer in the Chinese Han population

MicroRNA-27a (miR-27a) is deemed to be an oncogene that plays an important role in development of various cancers, and single nucleotide polymorphism (SNP) of miR-27a can influence the maturation or aberrant expression of hsa-miR27a, resulting in increased risk of cancer and poor prognosis for non-small cell lung cancer (NSCLC). This study aimed to assess the effects of rs895819 within miR-27a on susceptibility and prognosis of NSCLC patients in 560 clinical confirmed cases and 568 healthy check-up individuals. Adjusted odds/hazard ratios (ORs/HRs) and 95% confidential intervals (CIs) were calculated to evaluate the association between rs895819 and the risk and prognosis of NSCLC. The results showed that allele A and genotype GG of rs895819 were significantly associated with an increased risk of NSCLC (38.9% vs 30.8%, adjusted OR=1.26, 95%CI=1.23-1.29 for allele G vs A; 18.1% vs 11.7%, adjusted OR=1.67, 95%CI=1.59-1.75 for genotype GG vs AA). Moreover, positive associations were also observed in dominant and recessive models (53.7% vs 49.9%, adjusted OR=1.17, 95%CI=1.13-1.20 for GG/AG vs AA; 18.1% vs 11.7%, adjusted=1.65, 95%CI=1.58-1.73). However, no significant association was found between rs895819 and the prognosis of NSCLC in genotype, dominant and recessive models. These results suggested that miR-27a might be involved in NSCLC carcinogenesis, but not in progression of NSCLC. The allele G, genotype GG and allele G carrier (GG/AG vs AA) of rs895819 might be genetic susceptible factors for NSCLC. Further multi-central, large sample size and well-designed prospective studies as well as functional studies are warranted to verify our findings.

Regulating Fbw7 on the road to cancer

The F-box protein Fbw7 targets for degradation critical cellular regulators, thereby controlling essential processes in cellular homeostasis, including cell cycle, differentiation and apoptosis. Most Fbw7 substrates are strongly associated with tumorigenesis and Fbw7 can either suppress or promote tumor development in mouse models. Fbw7 activity is controlled at different levels, resulting in specific and tunable regulation of the abundance and activity of its substrates. Here we highlight recent studies on the role of Fbw7 in controlling tumorigenesis and on the mechanisms that modulate Fbw7 function.

MicroRNA regulation of F-box proteins and its role in cancer

MicroRNAs (miRNAs) are small endogenous non-coding RNAs, which play critical roles in cancer development by suppressing gene expression at the post-transcriptional level. In general, oncogenic miRNAs are upregulated in cancer, while miRNAs that act as tumor suppressors are downregulated, leading to decreased expression of tumor suppressors and upregulated oncogene expression, respectively. F-box proteins function as the substrate-recognition components of the SKP1-CUL1-F-box (SCF)-ubiquitin ligase complex for the degradation of their protein targets by the ubiquitin-proteasome system. Therefore F-box proteins and miRNAs both negatively regulate target gene expression post-transcriptionally. Since each miRNA is capable of fine-tuning the expression of multiple target genes, multiple F-box proteins may be suppressed by the same miRNA. Meanwhile, one F-box proteins could be regulated by several miRNAs in different cancer types. In this review, we will focus on miRNA-mediated downregulation of various F-box proteins, the resulting stabilization of F-box protein substrates and the impact of these processes on human malignancies. We provide insight into how the miRNA: F-box protein axis may regulate cancer progression and metastasis. We also consider the broader role of F-box proteins in the regulation of pathways that are independent of the ubiquitin ligase complex and how that impacts on oncogenesis. The area of miRNAs and the F-box proteins that they regulate in cancer is an emerging field and will inform new strategies in cancer treatment.

Dysregulation of ubiquitin ligases in cancer

Ubiquitin ligases (UBLs) are critical components of the ubiquitin proteasome system (UPS), which governs fundamental processes regulating normal cellular homeostasis, metabolism, and cell cycle in response to external stress signals and DNA damage. Among multiple steps of the UPS system required to regulate protein ubiquitination and stability, UBLs define specificity, as they recognize and interact with substrates in a temporally- and spatially-regulated manner. Such interactions are required for substrate modification by ubiquitin chains, which marks proteins for recognition and degradation by the proteasome or alters their subcellular localization or assembly into functional complexes. UBLs are often deregulated in cancer, altering substrate availability or activity in a manner that can promote cellular transformation. Such deregulation can occur at the epigenetic, genomic, or post-translational levels. Alterations in UBL can be used to predict their contributions, affecting tumor suppressors or oncogenes in select tumors. Better understanding of mechanisms underlying UBL expression and activities is expected to drive the development of next generation modulators that can serve as novel therapeutic modalities. This review summarizes our current understanding of UBL deregulation in cancer and highlights novel opportunities for therapeutic interventions.

Fbw7 and its counteracting forces in stem cells and cancer: Oncoproteins in the balance

Fbw7 is well characterised as a stem cell regulator and tumour suppressor, powerfully positioned to control proliferation, differentiation and apoptosis by targeting key transcription factors for ubiquitination and destruction. Evidence in support of these roles continues to accumulate from in vitro studies, mouse models and human patient data. Here we summarise the latest of these findings, highlighting the tumour-suppressive role of Fbw7 in multiple tissues, and the rare circumstances where Fbw7 activity can be oncogenic. We discuss mechanisms that regulate ubiquitination by Fbw7, including ubiquitin-specific proteases such as USP28 that counteract Fbw7 activity and thereby stabilise oncoproteins. Deubiquitination of key Fbw7 substrates to prevent their destruction is beginning to be appreciated as an important pro-tumourigenic mechanism. As the ubiquitin-proteasome system represents a largely untapped field for drug development, the interplay between Fbw7 and its counterpart deubiquitinating enzymes in tumours is likely to attract increasing interest and influence future treatment strategies.

Cardioprotective Signature of Short-Term Caloric Restriction

Objective

To understand the molecular pathways underlying the cardiac preconditioning effect of short-term caloric restriction (CR).

Background

Lifelong CR has been suggested to reduce the incidence of cardiovascular disease through a variety of mechanisms. However, prolonged adherence to a CR life-style is difficult. Here we reveal the pathways that are modulated by short-term CR, which are associated with protection of the mouse heart from ischemia.

Methods

Male 10-12 wk old C57bl/6 mice were randomly assigned to an ad libitum (AL) diet with free access to regular chow, or CR, receiving 30% less food for 7 days (d), prior to myocardial infarction (MI) via permanent coronary ligation. At d8, the left ventricles (LV) of AL and CR mice were collected for Western blot, mRNA and microRNA (miR) analyses to identify cardioprotective gene expression signatures. In separate groups, infarct size, cardiac hemodynamics and protein abundance of caspase 3 was measured at d2 post-MI.

Results

This short-term model of CR was associated with cardio-protection, as evidenced by decreased infarct size (18.5±2.4% vs. 26.6±1.7%, N=10/group; P=0.01). mRNA and miR profiles pre-MI (N=5/group) identified genes modulated by short-term CR to be associated with circadian clock, oxidative stress, immune function, apoptosis, metabolism, angiogenesis, cytoskeleton and extracellular matrix (ECM). Western blots pre-MI revealed CR-associated increases in phosphorylated Akt and GSK3ß, reduced levels of phosphorylated AMPK and mitochondrial related proteins PGC-1α, cytochrome C and cyclooxygenase (COX) IV, with no differences in the levels of phosphorylated eNOS or MAPK (ERK1/2; p38). CR regimen was also associated with reduced protein abundance of cleaved caspase 3 in the infarcted heart and improved cardiac function.

MicroRNA-Specificity Protein (Sp) Transcription Factor Interactions and Significance in Carcinogenesis

Specificity protein (Sp) transcription factors (TFs) such as Sp1, Sp3 and Sp4 are overexpressed in tumors and Sp1 is a negative prognostic factor for multiple tumor types. Sp TFs regulate expression of pro-oncogenic factors important for cell proliferation, survival, angiogenesis, migration/invasion and inflammation and the high expression of Sp TFs in tumors is primarily due to miRNAs. For example, expression of tumor-suppressor-like miRNAs such as miR-200b/c, miR-335, miR-22, miR-149 and others that inactivate Sp1 expression is low in many tumor types. Research in our laboratory has also demonstrated that high expression of Sp TFs is also due to miRNA-dependent inhibition of the transcriptional repressors ZBTB10 and ZBTB4 by miR-27a and miR-20a/miR-17p, respectively. Thus, miRNAs play a critical role in maintaining high levels of Sp1, Sp3, Sp4 and pro-oncogenic Sp-regulated genes in tumors and cancer cells, and there is ample evidence that anticancer agents targeting the miRNASp TF axis can be highly effective for cancer chemotherapy.

Aberrant regulation of FBW7 in cancer

FBW7 (F-box and WD repeat domain-containing 7) or Fbxw7 is a tumor suppressor, which promotes the ubiquitination and subsequent degradation of numerous oncoproteins including Mcl-1, Cyclin E, Notch, c- Jun, and c-Myc. In turn, FBW7 is regulated by multiple upstream factors including p53, C/EBP-δ, EBP2, Pin1, Hes-5 and Numb4 as well as by microRNAs such as miR-223, miR-27a, miR-25, and miR-129-5p. Given that the Fbw7 tumor suppressor is frequently inactivated or deleted in various human cancers, targeting FBW7 regulators is a promising anti-cancer therapeutic strategy.

Non-coding RNAs in lung cancer

The discovery that protein-coding genes represent less than 2% of all human genome, and the evidence that more than 90% of it is actively transcribed, changed the classical point of view of the central dogma of molecular biology, which was always based on the assumption that RNA functions mainly as an intermediate bridge between DNA sequences and protein synthesis machinery. Accumulating data indicates that non-coding RNAs are involved in different physiological processes, providing for the maintenance of cellular homeostasis. They are important regulators of gene expression, cellular differentiation, proliferation, migration, apoptosis, and stem cell maintenance. Alterations and disruptions of their expression or activity have increasingly been associated with pathological changes of cancer cells, this evidence and the prospect of using these molecules as diagnostic markers and therapeutic targets, make currently non-coding RNAs among the most relevant molecules in cancer research. In this paper we will provide an overview of non-coding RNA function and disruption in lung cancer biology, also focusing on their potential as diagnostic, prognostic and predictive biomarkers.

The sensitivity of gastric cancer to trastuzumab is regulated by the miR-223/FBXW7 pathway

A recent large-scale phase III study (the ToGA trial) demonstrated the significant efficacy of trastuzumab combined with chemotherapy in patients with HER2-positive gastric cancer. Although trastuzumab has become a key drug in cancer treatment, the resistance of breast cancer to trastuzumab is a major problem in clinical practice. However, it is unclear whether similar mechanisms of trastuzumab resistance are involved in gastric cancer (GC). The aim of the current study was to identify a novel micro-RNA (miR)/gene pathway that regulates the sensitivity of HER2-positive GC cells to trastuzumab. We focused on F-box and WD repeat domain-containing 7 (FBXW7), which is one of the major causes of drug resistance. We also identified miR-223, which can regulate FBXW7, using miR quantitative reverse transcription-PCR array analysis using by resistance cell line, which we established. Overexpression of miR-223 decreased FBXW7 expression and the sensitivity of GC cells to trastuzumab, while suppression of miR-223 restored FBXW7 expression and the sensitivity of GC cells to trastuzumab. Moreover, overexpression of miR-223 significantly suppressed trastuzumab-induced apoptosis. This study is the first report to reveal that the miR-223/FBXW7 pathway regulates the sensitivity of a HER2-positive GC cell line to trastuzumab through the modulation of apoptosis. These findings suggest that this pathway can be crucial for the mechanism of trastuzumab resistance in GC, which may lead to the development of individualized treatment in clinical practice.

AntagomiR-27a targets FOXO3a in glioblastoma and suppresses U87 cell growth in vitro and in vivo

OBJECTIVE

To study the effect of the antagomiR-27a inhibitor on glioblastoma cells.

METHODS

The miR- 27a expression level in specimens of human glioblastoma and normal human brain tissues excised during decompression for traumatic brain injury was assessed using qRT-PCR; The predicted target gene of miR-27a was screened out through bioinformatics databases, and the predicted gene was verified using genetic report assays; the effect of antagomiR-27a on the invasion and proliferation of glioma cells was analyzed using MTT assays and 5-ethynyl-2'-deoxyuridine (EdU) labeling. A xenograft glioblastoma model in BALB-c nude mice was established to detect the effect of antagomiR-27a on tumour growth.

RESULTS

qRT-PCR results showed that miR-27a significantly increased in specimens from glioblastoma comparing with normal human brain tissues. Th miR-27a inhibitor significantly suppressed invasion and proliferation of glioblastoma cells. FOXO3a was verified as a new target of miR-27a by Western blotting and reporter analyzes. Tumor growth in vivo was suppressed by administration of the miR-27a inhibitor.

CONCLUSION

MiR-27a may be up-regulated in human glioblastoma, and antagomiR-27a could inhibit the proliferation and invasion ability of glioblastoma cells.

Coordinated targeting of the EGFR signaling axis by microRNA-27a*

Epidermal growth factor receptor (EGFR) has been characterized as a critical factor in the development and progression of multiple solid tumors, including head and neck squamous cell carcinoma (HNSCC). However, monotherapy with EGFR-specific agents has not been as dramatic as preclinical studies have suggested. Since complex regulation of the EGFR signaling axis might confound current attempts to inhibit EGFR directly, we searched for microRNAs (miRNAs) that may target the EGFR signaling axis. We identified miR-27a (miR-27a-3p) and its complementary or star (*) strand, miR-27a* (miR-27a-5p), as novel miRNAs targeting EGFR, which were significantly downregulated in multiple HNSCC cell lines. Analysis of human specimens demonstrated that miR-27a* is significantly underexpressed in HNSCC as compared to normal mucosa. Increased expression of miR-27a* in HNSCC produced a profound cytotoxic effect not seen with miR-27a. Analysis for potential targets of miR-27a* led to the identification of AKT1 (protein kinase B) and mTOR (mammalian target of rapamycin) within the EGFR signaling axis. Treatment with miR-27a* led to coordinated downregulation of EGFR, AKT1 and mTOR. Overexpression of EGFR signaling pathway components decreased the overall effect of miR-27a* on HNSCC cell viability. Constitutive and inducible expression of miR-27a* in a murine orthotopic xenograft model of oral cavity cancer led to decreased tumor growth. Direct intratumoral injection of miR-27a* inhibited tumor growth in vivo. These findings identify miR-27a* as a functional star sequence that exhibits novel coordinated regulation of the EGFR pathway in solid tumors and potentially represents a novel therapeutic option.

miR-27a regulates inflammatory response of macrophages by targeting IL-10

Although microRNAs were shown to participate in innate immune responses, it is not completely understood how they regulate negative immunomodulatory events. IL-10 is an important anti-inflammatory mediator that prevents excessive inflammation and associated immunological pathologies. Although the regulation of IL-10 expression has been well studied at both the transcriptional and translational levels, it is less clear how microRNAs control IL-10 expression during inflammation. In this study, we found that miR-27a is downregulated in macrophages following stimulation through TLR2 and TLR4, but not TLR3. Upregulation of miR-27a enhanced the expression of proinflammatory cytokines in TLR2/4-activated macrophages. Conversely, knockdown of miR-27a diminished cytokine expression. Mechanistically, we found that miR-27a negatively regulates IL-10 expression; upregulation of miR-27a decreases, whereas downregulation of miR-27a increases, IL-10 expression in activated macrophages. Likely due to the decreased expression of IL-10, upregulation of miR-27a diminished IL-10-dependent STAT3 phosphorylation in TLR4-activated macrophages. Consistent with IL-10 being a potential mediator for the role of miR-27a in the immune response, blocking IL-10 abolished the enhancing effect of miR-27a on TLR4-activated inflammation. In conclusion, our study identified miR-27a downregulation as a negative-regulatory mechanism that prevents overly exuberant TLR2- and TLR4-driven inflammatory responses.

Imperfect centered miRNA binding sites are common and can mediate repression of target mRNAs

Background

MicroRNAs (miRNAs) bind to mRNAs and target them for translational inhibition or transcriptional degradation. It is thought that most miRNA-mRNA interactions involve the seed region at the 5′ end of the miRNA. The importance of seed sites is supported by experimental evidence, although there is growing interest in interactions mediated by the central region of the miRNA, termed centered sites. To investigate the prevalence of these interactions, we apply a biotin pull-down method to determine the direct targets of ten human miRNAs, including four isomiRs that share centered sites, but not seeds, with their canonical partner miRNAs.

Results

We confirm that miRNAs and their isomiRs can interact with hundreds of mRNAs, and that imperfect centered sites are common mediators of miRNA-mRNA interactions. We experimentally demonstrate that these sites can repress mRNA activity, typically through translational repression, and are enriched in regions of the transcriptome bound by AGO. Finally, we show that the identification of imperfect centered sites is unlikely to be an artifact of our protocol caused by the biotinylation of the miRNA. However, the fact that there was a slight bias against seed sites in our protocol may have inflated the apparent prevalence of centered site-mediated interactions.

Conclusions

Our results suggest that centered site-mediated interactions are much more frequent than previously thought. This may explain the evolutionary conservation of the central region of miRNAs, and has significant implications for decoding miRNA-regulated genetic networks, and for predicting the functional effect of variants that do not alter protein sequence.