Non-coding RNAs take centre stage in epithelial-to-mesenchymal transition

MicroRNA-200 Loaded Lipid Nanoparticles Promote Intestinal Epithelium Regeneration in Canonical MicroRNA-Deficient Mice

Intestinal epithelium undergoes regeneration after injuries, and the disruption of this process can lead to inflammatory bowel disease and tumorigenesis. Intestinal stem cells (ISCs) residing in the crypts are crucial for maintaining the intestinal epithelium's homeostasis and promoting regeneration upon injury. However, the precise role of DGCR8, a critical component in microRNA (miRNA) biogenesis, in intestinal regeneration remains poorly understood. In this study, we provide compelling evidence demonstrating the indispensable role of epithelial miRNAs in the regeneration of the intestine in mice subjected to 5-FU or irradiation-induced injury. Through a comprehensive pooled screen of miRNA function in Dgcr8-deficient organoids, we observe that the loss of the miR-200 family leads to the hyperactivation of the p53 pathway, thereby reducing ISCs and impairing epithelial regeneration. Notably, downregulation of the miR-200 family and hyperactivation of the p53 pathway are verified in colonic tissues from patients with active ulcerative colitis (UC). Most importantly, the transient supply of miR-200 through the oral delivery of lipid nanoparticles (LNPs) carrying miR-200 restores ISCs and promotes intestinal regeneration in mice following acute injury. Our study implies the miR-200/p53 pathway as a promising therapeutic target for active UC patients with diminished levels of the miR-200 family. Furthermore, our findings suggest that the clinical application of LNP-miRNAs could enhance the efficacy, safety, and acceptability of existing therapeutic modalities for intestinal diseases.

Reactivation of embryonic genetic programs in tissue regeneration and disease

Embryonic genetic programs are reactivated in response to various types of tissue damage, providing cell plasticity for tissue regeneration or disease progression. In acute conditions, these programs remedy the damage and then halt to allow a return to homeostasis. In chronic situations, including inflammatory diseases, fibrosis and cancer, prolonged activation of embryonic programs leads to disease progression and tissue deterioration. Induction of progenitor identity and cell plasticity, for example, epithelial-mesenchymal plasticity, are critical outcomes of reactivated embryonic programs. In this Review, we describe molecular players governing reactivated embryonic genetic programs, their role during disease progression, their similarities and differences and lineage reversion in pathology and discuss associated therapeutics and drug-resistance mechanisms across many organs. We also discuss the diversity of reactivated programs in different disease contexts. A comprehensive overview of commonalities between development and disease will provide better understanding of the biology and therapeutic strategies.

Long non-coding RNAs and circular RNAs in tumor angiogenesis: From mechanisms to clinical significance

Long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs) execute a wide array of functions in physiological and pathological processes, including tumor progression. Angiogenesis, an elaborate multistep process driving new blood vessel formation, accelerates cancer progression by supplying nutrients and energy. Dysregulated lncRNAs and circRNAs can reportedly impact cancer progression by influencing angiogenesis. However, the expanding landscape of lncRNAs and circRNAs in tumor progression-dependent angiogenesis remains largely unknown. This review summarizes the major functions of angiogenic lncRNAs (Angio-LncRs) and angiogenic circRNAs (termed Angio-CircRs) and their cancer mechanisms. Moreover, we highlight the commonalities of lncRNAs and circRNAs in epigenetic, transcriptional, and post-transcriptional regulation as well as illustrate how Angio-LncRs and Angio-CircRs induce cancer onset and progression. We also discuss their potential clinical applications in diagnosis, prognosis, and anti-angiogenic therapies.

Deletion of Yy1 in mouse lung epithelium unveils molecular mechanisms governing pleuropulmonary blastoma pathogenesis

Pleuropulmonary blastoma (PPB) is a very rare pediatric lung disease. It can progress from abnormal epithelial cysts to an aggressive sarcoma with poor survival. PPB is difficult to diagnose as it can be confounded with other cystic lung disorders, such as congenital pulmonary airway malformation (CPAM). PPB is associated with mutations in DICER1 that perturb the microRNA (miRNA) profile in lung. How DICER1 and miRNAs act during PPB pathogenesis remains unsolved. Lung epithelial deletion of the Yin Yang1 (Yy1) gene in mice causes a phenotype mimicking the cystic form of PPB and affects the expression of key regulators of lung development. Similar changes in expression were observed in PPB but not in CPAM lung biopsies, revealing a distinctive PPB molecular signature. Deregulation of molecules promoting epithelial-mesenchymal transition (EMT) was detected in PPB specimens, suggesting that EMT might participate in tumor progression. Changes in miRNA expression also occurred in PPB lung biopsies. miR-125a-3p, a candidate to regulate YY1 expression and lung branching, was abnormally highly expressed in PPB samples. Together, these findings support the concept that reduced expression of YY1, due to the abnormal miRNA profile resulting from DICER1 mutations, contributes to PPB development via its impact on the expression of key lung developmental genes.This article has an associated First Person interview with the joint first authors of the paper.

Cellular processes driving gastrulation in the avian embryo

Gastrulation consists in the dramatic reorganisation of the epiblast, a one-cell thick epithelial sheet, into a multilayered embryo. In chick, the formation of the internal layers requires the generation of a macroscopic convection-like flow, which involves up to 50,000 epithelial cells in the epiblast. These cell movements locate the mesendoderm precursors into the midline of the epiblast to form the primitive streak. There they acquire a mesenchymal phenotype, ingress into the embryo and migrate outward to populate the inner embryonic layers. This review covers what is currently understood about how cell behaviours ultimately cause these morphogenetic events and how they are regulated. We discuss 1) how the biochemical patterning of the embryo before gastrulation creates compartments of differential cell behaviours, 2) how the global epithelial flows arise from the coordinated actions of individual cells, 3) how the cells delaminate individually from the epiblast during the ingression, and 4) how cells move after the ingression following stereotypical migration routes. We conclude by exploring new technical advances that will facilitate future research in the chick model system.

Long non‑coding RNA ZEB1‑AS1 predicts a poor prognosis and promotes cancer progression through the miR‑200a/ZEB1 signaling pathway in intrahepatic cholangiocarcinoma

Emerging evidence suggests that long non‑coding RNAs (lncRNAs) play pivotal roles in cancer progression, including in intrahepatic cholangiocarcinoma (IHCC). The overexpression of lncRNA ZEB1 antisense 1 (ZEB1‑AS1) has been discovered in several types of cancer; however, the clinical significance and functional role of ZEB1‑AS1 in IHCC have not yet been determined. In the present study, ZEB1‑AS1 was found to be upregulated in IHCC cell lines and tissues. A high ZEB1‑AS1 expression was associated with clinical progression and a poor survival of patients with IHCC, and was identified as an independent risk factor for a poor prognosis. In addition, ZEB1‑AS1 promoted the proliferation and metastasis of IHCC cells both in vitro and in vivo. ZEB1‑AS1 was demonstrated to increase the expression of ZEB1 by sponging miR‑200a and to thereby accelerate epithelial‑mesenchymal transition (EMT). On the whole, the findings of the present study demonstrate that ZEB1‑AS1 promotes proliferation and metastasis in IHCC, and induces EMT through the miR‑200a/ZEB1 signaling pathway. ZEB1‑AS1 may thus be a promising prognostic biomarker and essential therapeutic target for IHCC.

lncRNA-H19/miR-29a axis affected the viability and apoptosis of keloid fibroblasts through acting upon COL1A1 signaling

This study was intended to clarify the potential of applying the long-chain noncoding RNA H19/miR-29a axis in keloid treatment by elucidating its correlation with the activity of fibroblasts. In this study, 80 keloid tissues, 63 normal fibrous tissues, and 91 normal skin tissues were collected in advance, and concurrently, fibroblasts separated from the tissues were cultured. Besides this, the si-H19, pcDNA3.1-H19, miR-29a mimic, and miR-29a inhibitor were transfected to keloid fibroblasts, whose proliferation, apoptosis, and metastasis were appraised by employing the colony formation assay, flow cytometry, and transwell assay. In addition, the luciferase reporter gene assay was carried out to determine whether targeted regulation was present between H19 and miR-29a, as well as between miR-29a and COL1A1. The study results demonstrated that keloid tissues and fibroblasts exhibited observably upregulated H19 expression and downregulated miR-29a expression, relative to normal skin tissues and fibroblasts (P < .05). Also observed was a negative correlation between H19 expression and miR-29a expression among the gathered keloid tissues (r_s  = -.267, P = .017). Furthermore, in vitro transfection of pcDNA3.1-H19 or miR-29a inhibitor could intensify viability, proliferation, migration, and invasion of the fibroblasts (P < .05), while silencing of H19 and overexpression of miR-29a hindered both metastasis and multiplication of the fibroblasts significantly (P < .05). In addition, H19 was capable of altering miR-29a expression within fibroblasts by directly sponging it, and overexpression of COL1A1 could deter the impact of miR-29a on viability, proliferation, migration, and invasion of fibroblasts (P < .05). In conclusion, H19 might facilitate proliferation and metastasis of fibroblasts by modifying downstream miR-29a and COL1A1, which was expected to allow for development of keloid-targeted treatments.

Epigenetic Regulation of Inflammatory Cytokine-Induced Epithelial-To-Mesenchymal Cell Transition and Cancer Stem Cell Generation

The neoplastic transformation of normal to metastatic cancer cells is a complex multistep process involving the progressive accumulation of interacting genetic and epigenetic changes that alter gene function and affect cell physiology and homeostasis. Epigenetic changes including DNA methylation, histone modifications and changes in noncoding RNA expression, and deregulation of epigenetic processes can alter gene expression during the multistep process of carcinogenesis. Cancer progression and metastasis through an ‘invasion–metastasis cascade’ involving an epithelial-to-mesenchymal cell transition (EMT), the generation of cancer stem cells (CSCs), invasion of adjacent tissues, and dissemination are fueled by inflammation, which is considered a hallmark of cancer. Chronic inflammation is generated by inflammatory cytokines secreted by the tumor and the tumor-associated cells within the tumor microenvironment. Inflammatory cytokine signaling initiates signaling pathways leading to the activation of master transcription factors (TFs) such as Smads, STAT3, and NF-κB. Moreover, the same inflammatory responses also activate EMT-inducing TF (EMT-TF) families such as Snail, Twist, and Zeb, and epigenetic regulators including DNA and histone modifying enzymes and micoRNAs, through complex interconnected positive and negative feedback loops to regulate EMT and CSC generation. Here, we review the molecular regulatory feedback loops and networks involved in inflammatory cytokine-induced EMT and CSC generation.

Traditional Chinese Medicine and regulatory roles on epithelial-mesenchymal transitions

Epithelial–mesenchymal transition (EMT) is a critical biological process allowing epithelial cells to de-differentiate into mesenchymal cells. Orchestrated signaling pathways cooperatively induce EMT and effect physiological, sometimes pathological outcomes. Traditional Chinese Medicine (TCM) has been clinically prescribed for thousands of years and recent studies have found that TCM therapies can participate in EMT regulation. In this review, the historical discovery of EMT will be introduced, followed by a brief overview of its major roles in development and diseases. The second section will focus on EMT in organ fibrosis and tissue regeneration. The third section discusses EMT-induced cancer metastasis, and details how EMT contribute to distant dissemination. Finally, new EMT players are described, namely microRNA, epigenetic modifications, and alternative splicing. TCM drugs that affect EMT proven through an evidence-based research approach will be presented in each section.

The mir-200 family regulates key pathogenic events in ascending aortas of individuals with bicuspid aortic valves

BACKGROUND

An individual with a bicuspid aortic valve (BAV) runs a substantially higher risk of developing aneurysm in the ascending aorta compared to the normal population with tricuspid aortic valves (TAV). Aneurysm formation in patients with BAV and TAV is known to be distinct at the molecular level but the underlying mechanisms are undefined. Here, we investigated the still incompletely described role of microRNAs (miRNAs), important post-transcriptional regulators of gene expression, in such aortic disease of patients with BAV as compared with TAV.

METHODS AND RESULTS

Using a system biology approach, based on data obtained from proteomic analysis of non-dilated aortas from BAV and TAV patients, we constructed a gene-interaction network of regulatory microRNAs associated with the observed differential protein signature. The miR-200 family was the highest ranked miRNA, hence potentially having the strongest effect on the signalling network associated with BAV. Further, qRT-PCR and ChIP analyses showed lower expression of miR-200c, higher expression of miR-200 target genes, ZEB1/ZEB2 transcription factors, and higher chromatin occupancy of the miR-200c promoter by ZEB1/ZEB2 in BAV patients, indicating a miR-200c/ZEBs negative feedback loop and induction of endothelial/epithelial mesenchymal transition (EndMT/EMT).

CONCLUSION

We propose that a miR-200-dependent process of EndMT/EMT is a plausible biological mechanism rendering the BAV ascending aorta more prone to aneurysm development. Although initially supported by a miR-200c/ZEB feedback loop, this process is most probably advanced by cooperation of other miRNAs.

Contribution of epithelial-mesenchymal transitions to organogenesis and cancer metastasis

The epithelial-to-mesenchymal transition (EMT) plays crucial roles during development, and inappropriate activation of EMTs are associated with tumor progression and promoting metastasis. In recent years, increasing studies have identified developmental contexts where cells undergo an EMT and transition to a partial-state, downregulating just a subset of epithelial characteristics and increasing only some mesenchymal traits, such as invasive motility. In parallel, recent studies have shown that EMTs are rarely fully activated in tumor cells, generating a diverse array of transition states. As our appreciation of the full spectrum of intermediate phenotypes and the huge diversity in underlying mechanisms grows, cross-disciplinary collaborations investigating developmental-EMTs and cancer-EMTs will be fundamental in order to achieve a full mechanistic understanding of this complex cell process.

The Kindlin-2 regulation of epithelial-to-mesenchymal transition in breast cancer metastasis is mediated through miR-200b

Metastasis is the main cause of death in cancer patients, including breast cancer (BC). Despite recent progress in understanding the biological and molecular determinants of BC metastasis, effective therapeutic treatments are yet to be developed. Among the multitude of molecular mechanisms that regulate cancer metastasis, the epithelial-to-mesenchymal transition (EMT) program plays a key role in the activation of the biological steps leading to the metastatic phenotype. Kindlin-2 has been associated with the pathogenesis of several types of cancers, including BC. The role of Kindlin-2 in the regulation of BC metastasis, and to a lesser extent in EMT is not well understood. In this study, we show that Kindlin-2 is closely associated with the development of the metastatic phenotype in BC. We report that knockout of Kindlin-2 in either human or mouse BC cells, significantly inhibits metastasis in both human and mouse models of BC metastasis. We also report that the Kindlin-2-mediated inhibition of metastasis is the result of inhibition of expression of key molecular markers of the EMT program. Mechanistically, we show that miR-200b, a master regulator of EMT, directly targets and inhibits the expression of Kindlin-2, leading to the subsequent inhibition of EMT and metastasis. Together, our data support the targeting of Kindlin-2 as a therapeutic strategy against BC metastasis.

Non-coding RNAs as emerging regulators of epithelial to mesenchymal transition in non-small cell lung cancer

Non-small cell lung cancer (NSCLC) remains a major health problem that patients suffer from around the world. The epithelial to mesenchymal transition (EMT) has attractive roles in increasing malignant potential and reducing sensitivity to conventional therapeutics in NSCLC cells. Meanwhile, it is now evident that non-coding RNAs (ncRNAs), primarily microRNAs and long non-coding RNAs contribute to tumorigenesis partially via regulating EMT. This article briefly summarizes current researches about EMT-related ncRNAs in NSCLC and discusses their crucial roles in the complex regulatory network. Also, the authors will show the evidence that ncRNAs not only contribute to cancer cells migration and invasion, but also take charge of the resistance of chemotherapy, radiotherapy and EGFR-TIKs. Then, we will further discuss the potential of inhibition of EMT via manipulating relevant ncRNAs to change our current treatment of NSCLC patients.

MicroRNA profiling study reveals miR-150 in association with metastasis in nasopharyngeal carcinoma

MicroRNAs (miRNAs) are small non-coding RNAs that play a crucial role in pathogenesis of human cancers. Several miRNAs have been shown to involve in nasopharyngeal carcinoma (NPC) pathogenesis through alteration of gene networks. A global view of the miRNA expression profile of clinical specimens would be the best way to screen out the possible miRNA candidates that may be involved in disease pathogenesis. In this study, we investigated the expression profiles of miRNA in formalin-fixed paraffin-embedded tissues from patients with undifferentiated NPC versus non-NPC controls using a miRNA real-time PCR platform, which covered a total of 95 cancer-related miRNAs. Hierarchical cluster analysis revealed that NPC and non-NPC controls were clearly segregated. Promisingly, 10 miRNA candidates were differentially expressed. Among them, 9 miRNAs were significantly up-regulated of which miR-205 and miR-196a showed the most up-regulated in NPC with the highest incidence percentage of 94.1% and 88.2%, respectively, while the unique down-regulated miR-150 was further validated in patient sera. Finally, the in vitro gain-of-function and loss-of-function assays revealed that miR-150 can modulate the epithelial-mesenchymal-transition property in NPC/HK-1 cells and led to the cell motility and invasion. miR-150 may be a potential biomarker for NPC and plays a critical role in NPC tumourigenesis.

Up-regulation of long non-coding RNA XLOC_010235 regulates epithelial-to-mesenchymal transition to promote metastasis by associating with Snail1 in gastric cancer

We previously performed long non-coding RNA (lncRNA) expression microarray analyses to identify novel indicators for gastric cancer (GC) metastasis and prognosis in which we identified lncRNA XLOC_010235 (XLOC) as a candidate RNA. However, XLOC_010235 molecular mechanism of action remains unclear. Gain and loss of function approaches were used to investigate the biological role of XLOC in vitro. The effects of XLOC on cell viability were assessed by CCK-8 proliferation assays. Real-time PCR, western-blot and immunofluorescence were used to evaluate the mRNA and protein expression of Snail and multiple EMT related molecules. The positive XLOC/Snail1 interaction was identified and verified by immunohistochemistry assay and bivariate correlation analysis. Ectopic expression of XLOC facilitate cell viability, migration and invasion, leading to the acceleration of metastasis, while depletion of XLOC expression hindered cell migration and invasion. Moreover, over-expression of XLOC was found to play a important role in epithelial-to-mesenchymal transition (EMT) through the regulation of E-cadherin, N-cadherin and Vimentin expression, in which transcriptional factor Snail1 was involved. These results advance our understanding of the role of lncRNA XLOC_010235 as a active regulator of EMT by associating with Snail1, which may help in the development of new therapeutics.

Re-expression of miR-200c suppresses proliferation, colony formation and in vivo tumor growth of murine claudin-low mammary tumor cells

Claudin-low breast cancer is a relatively rare breast cancer subtype. These cancers are typically ER-/PR-/HER2- and express high levels of mesenchymal genes as well as genes associated with inflammation, angiogenesis and stem cell function. In addition to alterations in gene expression, it was recently demonstrated that claudin-low breast cancers express very low levels of the miR-200 family of miRNAs. Given that each miRNA can regulate tens, hundreds or even thousands of genes, miRNAs are being evaluated as therapeutic targets. In this study we show that mammary tumors from MTB-IGFIR transgenic mice and cell lines derived from these tumors represent a model of human claudin-low breast cancer and murine claudin-low mammary tumors and cell lines express only very low levels of all five members of the miR-200 family. Reduced miR-200 family expression appears to be regulated via methylation as cells and tumors expressing low levels of miR-200 family members had higher levels of CpG methylation in a putative promoter region than tumors and cells expressing high levels of miR-200 family members. Re-expression of miR-200c in murine claudin-low mammary tumor cells inhibited tumor cell proliferation and colony formation in vitro and tumor growth in vivo. With respect to tumor growth in vivo, re-expression of miR-200c was associated with a reduction in tumor vasculature and expression of Flt1 and Vegfc. Therefore, miR-200c is an important regulator of mesenchymal tumor cell growth.

Altered microRNA expression patterns during the initiation and promotion stages of neonatal diethylstilbestrol-induced dysplasia/neoplasia in the hamster (Mesocricetus auratus) uterus

Treatment of Syrian hamsters on the day of birth with the prototypical endocrine disruptor and synthetic estrogen, diethylstilbestrol (DES), leads to 100% occurrence of uterine hyperplasia/dysplasia in adulthood, a large proportion of which progress to neoplasia (endometrial adenocarcinoma). Consistent with our prior gene expression analyses at the mRNA and protein levels, we now report (based on microarray, real-time polymerase chain reaction, and in situ hybridization analyses) that progression of the neonatal DES-induced dysplasia/neoplasia phenomenon in the hamster uterus also includes a spectrum of microRNA expression alterations (at both the whole-organ and cell-specific level) that differ during the initiation (upregulated miR-21, 200a, 200b, 200c, 29a, 29b, 429, 141; downregulated miR-181a) and promotion (downregulated miR-133a) stages of the phenomenon. The biological processes targeted by those differentially expressed miRNAs include pathways in cancer and adherens junction, plus regulation of the cell cycle, apoptosis, and miRNA functions, all of which are consistent with our model system phenotype. These findings underscore the need for continued efforts to identify and assess both the classical genetic and the more recently recognized epigenetic mechanisms that truly drive this and other endocrine disruption phenomena.

ΔNp63α and microRNAs: leveraging the epithelial-mesenchymal transition

The epithelial-mesenchymal transition (EMT) is a cellular reprogramming mechanism that is an underlying cause of cancer metastasis. Recent investigations have uncovered an intricate network of regulation involving the TGFβ, Wnt, and Notch signaling pathways and small regulatory RNA species called microRNAs (miRNAs). The activity of a transcription factor vital to the maintenance of epithelial stemness, ΔNp63α, has been shown to modulate the activity of these EMT pathways to either repress or promote EMT. Furthermore, ΔNp63α is a known regulator of miRNA, including those directly involved in EMT. This review discusses the evidence of ΔNp63α as a master regulator of EMT components and miRNA, highlighting the need for a deeper understanding of its role in EMT. This expanded knowledge may provide a basis for new developments in the diagnosis and treatment of metastatic cancer.

MiRNA-221-3p desensitizes pancreatic cancer cells to 5-fluorouracil by targeting RB1

Pancreatic cancer is a highly lethal disease due to its rapid dissemination and resistance to conventional chemotherapy. MicroRNAs (miRNAs) are emerging as novel regulators of chemoresistance, which modulate the expression of drug resistance-related genes. MiRNA-221 has been reported to be associated with chemoresistance in various types of cancer. But the detailed molecular mechanism about miR-221-3p regulating 5-fluorouracil (5-FU) resistance in human pancreatic cancer remains to be clarified. In this study, we investigated the association between miR-221-3p expression and 5-FU sensitivity. Studies on pancreatic cancer cell lines suggested an increased 5-FU resistance with miR-221-3p over-expression. In addition, the results indicated that miR-221-3p down-regulated RB1 expression by directly binding to its 3'-UTR and therefore caused increased several aspects of pancreatic cancer pathogenesis, including proliferation, migration, invasion, and epithelial-mesenchymal transition (EMT). Collectively, our findings revealed the important role of miR-221-3p in promoting 5-FU resistance of pancreatic cancer cells and provided a potential therapeutic target for pancreatic cancer.

A Polycomb-mir200 loop regulates clinical outcome in bladder cancer

Bladder cancer (BC) is a highly prevalent disease, ranking fifth in the most common cancers worldwide. Various miRNAs have recently emerged as potential prognostic biomarkers in cancer. The miR-200 family, which repressed the epithelial-to-mesenchymal transition (EMT), is repressed in multiple advanced cancers. However, its expression and function in BC is still poorly understood. Here we show that miR-200 family displays increased expression, probably due to the activation of specific oncogenic signaling pathways, and reduced promoter methylation, in BC compared to normal bladder samples. Furthermore, we show that the expression of these miRNAs is decreased in high grade and stage tumors, and the down-regulation is associated with patient's poor clinical outcome. Our data indicate that the miR-200 family plays distinct roles in Non-Muscle (NMIBC) and Muscle-Invasive BC (MIBC). In MIBC, miR-200 expression post transcriptionally regulates EMT-promoting transcription factors ZEB1 and ZEB2, whereas suppresses BMI1 expression in NMIBC. Interestingly, we show that increased EZH2 and/or BMI1 expression repress the expression of miR-200 family members. Collectively, these findings support a model of BC progression through a coordinated action between the Polycomb Repression Complex (PRC) members repressing the miR-200 expression, which ultimately favors invasive BC development. Since pharmacological inhibition of EZH2 in BC cell lines lead to increased miR-200 expression, our findings may support new therapeutic strategies for BC clinical management.

MicroRNA-320a promotes 5-FU resistance in human pancreatic cancer cells

The drug-resistance of pancreatic cancer cells results in poor therapeutic effect. To predict the therapeutic effect of the chemotherapy drugs to specific patients and to reverse the resistance of pancreatic cancer cells are critical for chemotherapy of pancreatic cancer. MicroRNAs (miRNAs) have been reported to play important roles in the genesis of drug-resistance of various cancer types. There are also many advantages of miRNAs in diagnosis and therapy of disease. Although several miRNAs regulating 5-Fluorouracil (5-FU) resistance in human pancreatic cancer have been reported, the detailed molecular mechanism remains to be determined. In this study, we found that miR-320a was significantly up-regulated in 5-FU resistant pancreatic cancer cells. Over-expression of miR-320a strongly contributed to pathogenesis of pancreatic cancer, which was represented by the increased proliferation, invasion, metastasis, drug-resistance characteristics and the epithelial-to-mesenchymal transition. Furthermore, we demonstrated that miR-320a was able to bind to 3'UTR of PDCD4 mRNA, and mediated its down-regulation in 5-FU resistance of human pancreatic cancer cells. Whereas restoration of PDCD4 expression could partially attenuate the function of miR-320a in pancreatic cancer. Taken together, our study demonstrated that miR-320a played important role in regulating 5-FU resistance by targeting PDCD4 and might be developed as new therapeutic target for pancreatic cancer.

High-throughput mRNA and miRNA profiling of epithelial-mesenchymal transition in MDCK cells

BACKGROUND

Epithelial-mesenchymal transition (EMT) is an important process in embryonic development, especially during gastrulation and organ formation. Furthermore EMT is widely observed in pathological conditions, e.g., fibrosis, tumor progression and metastasis. Madin-Darby Canine Kidney (MDCK) cells are widely used for studies of EMT and epithelial plasticity. MDCK cells show an epithelial phenotype, while oncogenic Ras-transformed MDCK (MDCK-Ras) cells undergo EMT and show a mesenchymal phenotype.

METHODS

RNA-Seq and miRNA-Seq analyses were performed on MDCK and MDCK-Ras cells. Data were validated by qRT-PCR. Gene signature analyses were carried out to identify pathways and gene ontology terms. For selected miRNAs target prediction was performed.

RESULTS

With RNA-Seq, mRNAs of approximately half of the genes known for dog were detected. These were screened for differential regulation during Ras-induced EMT. We went further and performed gene signature analyses and found Gene Ontology (GO) terms and pathways important for epithelial polarity and implicated in EMT. Among the identified pathways, TGFβ1 emerged as a central signaling factor in many EMT related pathways and biological processes. With miRNA-Seq, approximately half of the known canine miRNAs were found expressed in MDCK and MDCK-Ras cells. Furthermore, among differentially expressed miRNAs, miRNAs that are known to be important regulators of EMT were detected and new candidates were predicted. New dog miRNAs were discovered after aligning our reads to that of other species in miRBase. Importantly, we could identify 25 completely novel miRNAs with a stable hairpin structure. Two of these novel miRNAs were differentially expressed. We validated the two novel miRNAs with the highest read counts by RT-qPCR. Target prediction of a particular novel miRNA highly expressed in mesenchymal MDCK-Ras cells revealed that it targets components of epithelial cell junctional complexes. Combining target prediction for the most upregulated miRNAs and validation of the targets in MDCK-Ras cells with pathway analysis allowed us to identify two novel pathways, e.g., JAK/STAT signaling and pancreatic cancer pathways. These pathways could not be detected solely by gene set enrichment analyses of RNA-Seq data.

CONCLUSION

With deep sequencing data of mRNAs and miRNAs of MDCK cells and of Ras-induced EMT in MDCK cells, differentially regulated mRNAs and miRNAs are identified. Many of the identified genes are within pathways known to be involved in EMT. Novel differentially upregulated genes in MDCK cells are interferon stimulated genes and genes involved in Slit and Netrin signaling. New pathways not yet linked to these processes were identified. A central pathway in Ras induced EMT is TGFβ signaling, which leads to differential regulation of many target genes, including miRNAs. With miRNA-Seq we identified miRNAs involved in either epithelial cell biology or EMT. Finally, we describe completely novel miRNAs and their target genes.

Role of BioResponse 3,3'-Diindolylmethane in the Treatment of Human Prostate Cancer: Clinical Experience

Castration-resistant prostate cancer (CRPC) progression after androgen deprivation therapy shows upregulated expression of androgen receptor (AR) splice variants, induced epithelial-to-mesenchymal transition phenotypes and enhanced stem cell characteristics, all of which are associated with resistance to enzalutamide. Since there is no curative treatment for CRPC, innovative treatments are urgently needed. In our recent study, we found that resistance to enzalutamide was partly due to deregulated expression of microRNAs such as miR-34a, miR-124, miR-27b, miR-320 and let-7, which play important roles in regulating AR and stem cell marker gene expression that appears to be linked with resistance to enzalutamide. Importantly, we found that BioResponse 3,3'-diindolylmethane (BR-DIM) treatment in vitro and in vivo caused downregulation in the expression of wild-type AR. The AR splice variants, Lin28B and EZH2, appear to be deregulated through the re-expression of let-7, miR-27b, miR-320 and miR-34a in human prostate cancer (PCa). BR-DIM administered in clinical trials was well tolerated, and 93% of patients had detectable prostatic DIM levels. The inhibitory effects of BR-DIM on AR and AR target gene such as prostate-specific antigen were also observed in the clinical trial. Our preclinical and clinical studies provide the scientific basis for a 'proof-of-concept' clinical trial in CRPC patients treated with enzalutamide in combination with BR-DIM. This strategy could be expanded in future clinical trials in patients with PCa to determine whether or not they could achieve a better treatment outcome which could be partly mediated by delaying or preventing the development of CRPC.

Transcription Factor Hepatocyte Nuclear Factor-1β (HNF-1β) Regulates MicroRNA-200 Expression through a Long Noncoding RNA

The transcription factor hepatocyte nuclear factor-1β (HNF-1β) regulates tissue-specific gene expression in the kidney and other epithelial organs. Mutations of HNF-1β produce kidney cysts, and previous studies have shown that HNF-1β regulates the transcription of cystic disease genes, including Pkd2 and Pkhd1. Here, we combined chromatin immunoprecipitation and next-generation sequencing (ChIP-Seq) with microarray analysis to identify microRNAs (miRNAs) that are directly regulated by HNF-1β in renal epithelial cells. These studies identified members of the epithelial-specific miR-200 family (miR-200b/200a/429) as novel transcriptional targets of HNF-1β. HNF-1β binds to two evolutionarily conserved sites located 28 kb upstream to miR-200b. Luciferase reporter assays showed that the HNF-1β binding sites were located within a promoter that was active in renal epithelial cells. Mutations of the HNF-1β binding sites abolished promoter activity. RT-PCR analysis revealed that a long noncoding RNA (lncRNA) is transcribed from the promoter and encodes the miR-200 cluster. Inhibition of the lncRNA with siRNAs decreased the levels of miR-200 but did not affect expression of the Ttll10 host gene. The expression of the lncRNA and miR-200 was decreased in kidneys from HNF-1β knock-out mice and renal epithelial cells expressing dominant-negative mutant HNF-1β. The expression of miR-200 targets, Zeb2 and Pkd1, was increased in HNF-1β knock-out kidneys and in cells expressing mutant HNF-1β. Overexpression of miR-200 decreased the expression of Zeb2 and Pkd1 in HNF-1β mutant cells. These studies reveal a novel pathway whereby HNF-1β directly contributes to the control of miRNAs that are involved in epithelial-mesenchymal transition and cystic kidney disease.

Proteasome inhibitor-resistant cells cause EMT-induction via suppression of E-cadherin by miR-200 and ZEB1

Downregulation of E-cadherin (gene: CDH1) plays an important role in epithelial-mesenchymal transition (EMT), which is critical for normal development and disease states. As a result of long-term treatment of endometrial carcinoma Ishikawa cells with epoxomicin (EXM), the cells exhibited the phenotype for EXM-resistance (Ish/EXM cells). Moreover, CDH1 mRNA and its protein were suppressed and EMT was induced in Ish/EXM cells. Ish/EXM cells exhibited drug-resistance to other proteasome inhibitors, MG-132, PSI and PS-341 (Bortezomib). The proteasome inhibitor-resistant cells acquired invasiveness as a result of the chemotherapy. In Ish/EXM cells, E-cadherin was suppressed by upregulation of its transcriptional repressor ZEB1. Furthermore, expression of the miR-200 family (miR-200a, miR-200b, miR-200c and miR-141) found in Ishikawa cells was suppressed in Ish/EXM cells. Overexpression of the miR-200 family in Ish/EXM cells caused by transfection with the pre-miR-200 family induced downregulation of ZEB1 and enhanced expression of E-cadherin. Conversely, suppression of miR-200 expression in the Ishikawa cells by transfection with anti-miR-200 elevated the expression of ZEB1 and suppressed the expression of E-cadherin. These results suggest that acquirement of EXM-resistance in Ish/EXM cells induces up regulation of ZEB1 via suppression of the miR-200 family following suppression of E-cadherin. Since suppression of ZEB1 in Ish/EXM cells by treatment with its siRNA did not restore the miR-200 family expression, miR-200 family was placed upstream of ZEB1 to regulate the expression.

Zeb1 and Snail1 engage miR-200f transcriptional and epigenetic regulation during EMT

Cell plasticity is emerging as a key regulator of tumor progression and metastasis. During carcinoma dissemination epithelial cells undergo epithelial to mesenchymal transition (EMT) processes characterized by the acquisition of migratory/invasive properties, while the reverse, mesenchymal to epithelial transition (MET) process, is also essential for metastasis outgrowth. Different transcription factors, called EMT-TFs, including Snail, bHLH and Zeb families are drivers of the EMT branch of epithelial plasticity, and can be post-transcriptionally downregulated by several miRNAs, as the miR-200 family. The specific or redundant role of different EMT-TFs and their functional interrelations are not fully understood. To study the interplay between different EMT-TFs, comprehensive gain and loss-of-function studies of Snail1, Snail2 and/or Zeb1 factors were performed in the prototypical MDCK cell model system. We here describe that Snail1 and Zeb1 are mutually required for EMT induction while continuous Snail1 and Snail2 expression, but not Zeb1, is needed for maintenance of the mesenchymal phenotype in MDCK cells. In this model system, EMT is coordinated by Snail1 and Zeb1 through transcriptional and epigenetic downregulation of the miR-200 family. Interestingly, Snail1 is involved in epigenetic CpG DNA methylation of the miR-200 loci, essential to maintain the mesenchymal phenotype. The present results thus define a novel functional interplay between Snail and Zeb EMT-TFs in miR-200 family regulation providing a molecular link to their previous involvement in the generation of EMT process in vivo.

Friend or foe: Endoplasmic reticulum protein 29 (ERp29) in epithelial cancer

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ERp29 regulates epithelial cell plasticity and the mesenchymal–epithelial transition.

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ERp29 shows a tumor suppressive function in primary tumor development.

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ERp29 is potentially associated with distant metastasis in cancer.

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ERp29 modulates cell survival against genotoxic stress.

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Thus, ERp29 displays dual functions as a “friend or foe” in epithelial cancer.

The endoplasmic reticulum (ER) protein 29 (ERp29) is a molecular chaperone that plays a critical role in protein secretion from the ER in eukaryotic cells. Recent studies have also shown that ERp29 plays a role in cancer. It has been demonstrated that ERp29 is inversely associated with primary tumor development and functions as a tumor suppressor by inducing cell growth arrest in breast cancer. However, ERp29 has also been reported to promote epithelial cell morphogenesis, cell survival against genotoxic stress and distant metastasis. In this review, we summarize the current understanding on the biological and pathological functions of ERp29 in cancer and discuss the pivotal aspects of ERp29 as “friend or foe” in epithelial cancer.

Deletion of the miR-143/145 cluster leads to hydronephrosis in mice

Obstructive nephropathy, the leading cause of kidney failure in children, can be anatomic or functional. The underlying causes of functional hydronephrosis are not well understood. miRNAs, which are small noncoding RNAs, regulate gene expression at the post-transcriptional level. We found that miR-145-5p, a member of the miR-143/145 cluster that is highly expressed in smooth muscle cells of the renal vasculature, was present in the pelvicalyceal system and the ureter. To evaluate whether the miR-143/145 cluster is involved in urinary tract function we performed morphologic, functional, and gene expression studies in mice carrying a whole-body deletion of miR-143/145. miR-143/145-deficient mice developed hydronephrosis, characterized by severe papillary atrophy and dilatation of the pelvicalyceal system without obvious physical obstruction. Moreover, mutant mice showed abnormal ureteral peristalsis. The number of ureter contractions was significantly higher in miR-143/145-deficient mice. Peristalsis was replaced by incomplete, short, and more frequent contractions that failed to completely propagate in a proximal-distal direction. Microarray analysis showed 108 differentially expressed genes in ureters of miR-143/145-deficient mice. Ninety genes were up-regulated and 18 genes were down-regulated, including genes with potential regulatory roles in smooth muscle contraction and extracellular matrix-receptor interaction. We show that miR-143/145 are important for the normal peristalsis of the ureter and report an association between the expression of these miRNAs and hydronephrosis.

Functional linc-POU3F3 is overexpressed and contributes to tumorigenesis in glioma

Growing number of long intergenic noncoding RNAs (lincRNAs) have recently been identified in mammals as new modulators in cancer origination and progression involved in a broad range of biological processes. Long intergenic noncoding RNA POU3F3 (linc-POU3F3) has been characterized as a highly conserved functional transcription regulator in esophageal squamous cell carcinoma. The contributions of this lincRNA to glioblastoma remain unknown. In this present study, we investigated the expression pattern and functional role of linc-POU3F3 in glioma by using real-time PCR and gain-/loss-of-function studies. The results revealed that linc-POU3F3 levels were extraordinarily associated with the tumor WHO grade. In related biochemical assays, overexpression of linc-POU3F3 promotes cell viability and proliferation in glioma cells, whereas knockdown of linc-POU3F3 showed the opposite effect. As expected, we also found that linc-POU3F3 expression was negatively correlated with the mRNA level of POU3F3 (the evolutionarily conserved neighbor gene of linc-POU3F3). Our results indicate that linc-POU3F3 might affect glioma development via altering expression level of POU3F3, and lead us to believe that linc-POU3F3 may also have a crucial regulatory role in glioma progression.

Uncovering molecular events associated with the chemosuppressive effects of flaxseed: a microarray analysis of the laying hen model of ovarian cancer

Background

The laying hen model of spontaneous epithelial ovarian cancer (EOC) is unique in that it is the only model that enables observations of early events in disease progression and is therefore also uniquely suited for chemoprevention trials. Previous studies on the effect of dietary flaxseed in laying hens have revealed the potential for both amelioration and prevention of ovarian cancer. The objective of this study was to assess the effect of flaxseed on genes and pathways that are dysregulated in tumors. We have used a bioinformatics approach to identify these genes, followed by qPCR validation, immunohistochemical localization, and in situ hybridization to visualize expression in normal ovaries and tumors from animals fed a control diet or a diet containing 10% flaxseed.

Results

Bioinformatic analysis of ovarian tumors in hens led to the identification of a group of highly up-regulated genes that are involved in the embryonic process of branching morphogenesis. Expression of these genes coincides with expression of E-cadherin in the tumor epithelium. Levels of expression of these genes in tumors from flax-fed animals are reduced 40-60%. E-cadherin and miR200 are both up-regulated in tumors from control-fed hens, whereas their expression is decreased 60-75% in tumors from flax-fed hens. This does not appear to be due to an increase in ZEB1 as mRNA levels are increased five-fold in tumors, with no significant difference between control-fed and flax-fed hens.

Conclusions

We suggest that nutritional intervention with flaxseed targets the pathways regulating branching morphogenesis and thereby alters the progression of ovarian cancer.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2164-15-709) contains supplementary material, which is available to authorized users.

The decalog of long non-coding RNA involvement in cancer diagnosis and monitoring

Long non-coding RNAs (lncRNAs) are transcripts without protein-coding capacity; initially regarded as "transcriptional noise", lately they have emerged as essential factors in both cell biology and mechanisms of disease. In this article, we present basic knowledge of lncRNA molecular mechanisms, associated physiological processes and cancer association, as well as their diagnostic and therapeutic value in the form of a decalog: (1) Non-coding RNAs (ncRNAs) are transcripts without protein-coding capacity divided by size (short and long ncRNAs), function (housekeeping RNA and regulatory RNA) and direction of transcription (sense/antisense, bidirectional, intronic and intergenic), containing a broad range of molecules with diverse properties and functions, such as messenger RNA, transfer RNA, microRNA and long non-coding RNAs. (2) Long non-coding RNAs are implicated in many molecular mechanisms, such as transcriptional regulation, post-transcriptional regulation and processing of other short ncRNAs. (3) Long non-coding RNAs play an important role in many physiological processes such as X-chromosome inactivation, cell differentiation, immune response and apoptosis. (4) Long non-coding RNAs have been linked to hallmarks of cancer: (a) sustaining proliferative signaling; (b) evading growth suppressors; (c) enabling replicative immortality; (d) activating invasion and metastasis; (e) inducing angiogenesis; (f) resisting cell death; and (g) reprogramming energy metabolism. (5) Regarding their impact on cancer cells, lncRNAs are divided into two groups: oncogenic and tumor-suppressor lncRNAs. (6) Studies of lncRNA involvement in cancer usually analyze deregulated expression patterns at the RNA level as well as the effects of single nucleotide polymorphisms and copy number variations at the DNA level. (7) Long non-coding RNAs have potential as novel biomarkers due to tissue-specific expression patterns, efficient detection in body fluids and high stability. (8) LncRNAs serve as novel biomarkers for diagnostic, prognostic and monitoring purposes. (9) Tissue specificity of lncRNAs enables the development of selective therapeutic options. (10) Long non-coding RNAs are emerging as commercial biomarkers and therapeutic agents.

Role of microRNA in epithelial to mesenchymal transition and metastasis and clinical perspectives

The microRNAs (miRNAs) are a class of small, 20–22 nucleotides in length, endogenously expressed noncoding RNAs that regulate multiple targets posttranscriptionally. Interestingly, miRNAs have emerged as regulators of most physiological and pathological processes, including metastatic tumor progression, in part by controlling a reversible process called epithelial-to-mesenchymal transition (EMT). The activation of EMT increases the migratory and invasive properties fundamental for tumor cell spread while activation of the reverse mesenchymal-to-epithelial transition is required for metastasis outgrowth. The EMT triggering leads to the activation of a core of transcription factors (EMT-TFs) – SNAIL1/SNAIL2, bHLH (E47, E2-2, and TWIST1/TWIST2), and ZEB1/ZEB2 – that act as E-cadherin repressors and, ultimately, coordinate EMT. Recent evidence indicates that several miRNAs regulate the expression of EMT-TFs or EMT-activating signaling pathways. Interestingly, some miRNAs and EMT-TFs form tightly interconnected negative feedback loops that control epithelial cell plasticity, providing self-reinforcing signals and robustness to maintain the epithelial or mesenchymal cell status. Among the most significant feedback loops, we focus on the ZEB/miR-200 and the SNAIL1/miR-34 networks that hold a clear impact in the regulation of the epithelial-mesenchymal state. Recent insights into the p53 modulation of the EMT-TF/miRNA loops and epigenetic regulatory mechanisms in the context of metastasis dissemination will also be discussed. Understanding the regulation of EMT by miRNAs opens new avenues for the diagnosis and prognosis of tumors and identifies potential therapeutic targets that might help to negatively impact on metastasis dissemination and increasing patient survival.

Downregulation of BRAF activated non-coding RNA is associated with poor prognosis for non-small cell lung cancer and promotes metastasis by affecting epithelial-mesenchymal transition

Background

Recent evidence indicates that long noncoding RNAs (lncRNAs) play a critical role in the regulation of cellular processes, such as differentiation, proliferation and metastasis. These lncRNAs are found to be dysregulated in a variety of cancers. BRAF activated non-coding RNA (BANCR) is a 693-bp transcript on chromosome 9 with a potential functional role in melanoma cell migration. The clinical significance of BANCR, and its’ molecular mechanisms controlling cancer cell migration and metastasis are unclear.

Methods

Expression of BANCR was analyzed in 113 non-small cell lung cancer (NSCLC) tissues and seven NSCLC cell lines using quantitative polymerase chain reaction (qPCR) assays. Gain and loss of function approaches were used to investigate the biological role of BANCR in NSCLC cells. The effects of BANCR on cell viability were evaluated by MTT and colony formation assays. Apoptosis was evaluated by Hoechst staining and flow cytometry. Nude mice were used to examine the effects of BANCR on tumor cell metastasis in vivo. Protein levels of BANCR targets were determined by western blotting and fluorescent immunohistochemistry.

Results

BANCR expression was significantly decreased in 113 NSCLC tumor tissues compared with normal tissues. Additionally, reduced BANCR expression was associated with larger tumor size, advanced pathological stage, metastasis distance, and shorter overall survival of NSCLC patients. Reduced BANCR expression was found to be an independent prognostic factor for NSCLC. Histone deacetylation was involved in the downregulation of BANCR in NSCLC cells. Ectopic expression of BANCR impaired cell viability and invasion, leading to the inhibition of metastasis in vitro and in vivo. However, knockdown of BANCR expression promoted cell migration and invasion in vitro. Overexpression of BANCR was found to play a key role in epithelial-mesenchymal transition (EMT) through the regulation of E-cadherin, N-cadherin and Vimentin expression.

Conclusion

We determined that BANCR actively functions as a regulator of EMT during NSCLC metastasis, suggesting that BANCR could be a biomarker for poor prognosis of NSCLC.

The anti-tumor activity of E1A and its implications in cancer therapy

The adenovirus type 5 E1A protein (E1A) plays a critical role in anti-cancer gene therapy and has been tested in clinical trials. The expression of E1A significantly reduces tumorigenesis, promotes cell death, and inhibits cancer cell mobility. Chemosensitization is one of the anti-tumor effects of E1A, increasing in vitro and in vivo sensitization of anti-cancer drugs, including cisplatin, gemcitabine, etoposide, doxorubicin, paclitaxel, and tumor necrosis factor-related apoptosis-inducing ligand and histone deacetylase inhibitors in different types of cancer cells. E1A also demonstrates anti-metastasis activity through various molecular mechanisms such as the repression of protease expression, suppression of HER2/neu and downregulation of microRNA (miR-520h). Moreover, E1A has been reported to reprogram transcription in tumor cells and stabilize tumor suppressors such as PP2A/C, p21 and p53. Because E1A plays a potentially significant role in anti-tumor therapy, there exists an urgent need to study the anti-cancer activities of E1A. This paper presents a review of our current understanding of the tumor-suppressive functions and molecular regulation of E1A, as well as the potential clinical applications of E1A.

FOXM1 and its oncogenic signaling in pancreatic cancer pathogenesis

Pancreatic cancer is a devastating disease with an overall 5-year survival rate less than 5%. Multiple signaling pathways are implicated in the pathogenesis of pancreatic cancer, such as Wnt/β-catenin, Notch, Hedgehog, hypoxia-inducible factor, signal transducer and activator of transcription, specificity proteins/Krüppel-like factors, and Forkhead box (FOX). Recently, increasing evidence has demonstrated that the transcription factor FOXM1 plays important roles in the initiation, progression, and metastasis of a variety of human tumors, including pancreatic cancer. In this review, we focus on the current understanding of the molecular pathogenesis of pancreatic cancer with a special focus on the function and regulation of FOXM1 and rationale for FOXM1 as a novel molecular target for pancreatic cancer prevention and treatment.

Cells susceptible to epithelial-mesenchymal transition are enriched in stem-like side population cells from prostate cancer

Accumulating evidence suggests that epithelial-mesenchymal transition (EMT) acts as an important factor for the promotion of tumor progression. Strategies for suppressing EMT remain the subject of ongoing research. In the present study, fluorescence-activated cell sorting (FACS) was used to isolate side population (SP) cells from human prostate cancer (PCa) cell lines and xenograft tissues. After identifying their molecular and functional stem-like characteristics, stem-like SP cells from a cell line and from xenograft tissue were transfected with hypoxia inducible factor-1α (HIF-1α). The potential of the prostate stem-like SP cells to undergo EMT was compared with that in their bulk counterparts after HIF-1α introduction. Stem-like SP cells acquired more complete EMT molecular features and exhibited stronger aggressive capability than the homologous bulk population cells both in vitro (proliferation and invasion) and in vivo (tumorigenesis and metastasis formation). We, therefore, concluded that EMT is closely associated with tumor heterogeneity, and that PCa cells susceptible to EMT are enriched in stem-like SP cells. These findings disclose a new approach, targeting the cellular basis of the EMT process that may help to identify effective and accurate methods for suppressing tumor growth and preventing distant dissemination.

miR-320a suppresses colorectal cancer progression by targeting Rac1

MicroRNAs (miRNAs) have emerged as critical epigenetic regulators involved in cancer progression. miR-320a has been identified to be a novel tumour suppressive miRNA in colorectal cancer (CRC). However, the detailed molecular mechanisms are not fully understood. Here, we reported that miR-320a inversely associated with CRC aggressiveness in both cell lines and clinical specimens. Functional studies demonstrated that miR-320a significantly decreased the capability of cell migration/invasion and induced G0/G1 growth arrest in vitro and in vivo. Furthermore, Rac1 was identified as one of the direct downstream targets of miR-320a and miR-320a specifically binds to the conserved 8-mer at position 1140-1147 of Rac1 3'-untranslated region to regulate Rac1 protein expression. Over-expression of miR-320a in SW620 cells inhibited Rac1 expression, whereas reduction of miR-320a by anti-miR-320a in SW480 cells enhanced Rac1 expression. Re-expression of Rac1 in the SW620/miR-320a cells restored the cell migration/invasion inhibited by miR-320a, whereas knockdown of Rac1 in the SW480/anti-miR-320a cells repressed these cellular functions elevated by anti-miR-320a. Conclusively, our results demonstrate that miR-320a functions as a tumour-suppressive miRNA through targeting Rac1 in CRC.

MiR-200, a new star miRNA in human cancer

MicroRNAs (miRNAs) are a set of non-coding small RNA molecules in control of gene expression at posttranscriptional/translational level. They not only play crucial roles in normal developmental progress, but also are commonly dysregulated in human diseases, including cancer. MiR-200 is a family of tumor suppressor miRNAs consisting of five members, which are significantly involved in inhibition of epithelial-to-mesenchymal transition (EMT), repression of cancer stem cells (CSCs) self-renewal and differentiation, modulation of cell division and apoptosis, and reversal of chemoresistance. In this article, we summarize the latest findings with regard to the tumor suppressor signatures of miR-200 and the regulatory mechanisms of miR-200 expression. The collected evidence supports that miR-200 is becoming a new star miRNA in study of human cancer.

Cancer Stem Cells and Epithelial-to-Mesenchymal Transition (EMT)-Phenotypic Cells: Are They Cousins or Twins?

Cancer stem cells (CSCs) are cells within a tumor that possess the capacity to self-renew and maintain tumor-initiating capacity through differentiation into the heterogeneous lineages of cancer cells that comprise the whole tumor. These tumor-initiating cells could provide a resource for cells that cause tumor recurrence after therapy. Although the cell origin of CSCs remains to be fully elucidated, mounting evidence has demonstrated that Epithelial-to-Mesenchymal Transition (EMT), induced by different factors, is associated with tumor aggressiveness and metastasis and these cells share molecular characteristics with CSCs, and thus are often called cancer stem-like cells or tumor-initiating cells. The acquisition of an EMT phenotype is a critical process for switching early stage carcinomas into invasive malignancies, which is often associated with the loss of epithelial differentiation and gain of mesenchymal phenotype. Recent studies have demonstrated that EMT plays a critical role not only in tumor metastasis but also in tumor recurrence and that it is tightly linked with the biology of cancer stem-like cells or cancer-initiating cells. Here we will succinctly summarize the state-of-our-knowledge regarding the molecular similarities between cancer stem-like cells or CSCs and EMT-phenotypic cells that are associated with tumor aggressiveness focusing on solid tumors.

HOTAIR, a cell cycle-associated long noncoding RNA and a strong predictor of survival, is preferentially expressed in classical and mesenchymal glioma

BACKGROUND

Long noncoding RNA Hox transcript antisense intergenic RNA (HOTAIR) has been characterized as a negative prognostic factor in breast and colon cancer patients. The clinical significance and function of HOTAIR in glioma remains unclear.

METHODS

We analyzed the clinical significance of HOTAIR in 3 different glioma cohorts with gene expression data, including correlation with tumor grade, prognosis, and molecular subtype. The function of HOTAIR in glioma was explored by performing gene set enrichment analysis and in vitro and in vivo experiments.

RESULTS

HOTAIR expression was closely associated with glioma grade and poor prognosis. Multivariate Cox regression analysis revealed that HOTAIR was an independent prognostic factor in glioblastoma multiforme patients. HOTAIR expression correlated with glioma molecular subtype, including those of The Cancer Genome Atlas. HOTAIR was preferentially expressed in the classical and mesenchymal subtypes compared with the neural and proneural subtypes. A gene set enrichment analysis designed to show gene set differences between patients with high and low HOTAIR expression indicated that HOTAIR expression was associated with gene sets involved in cell cycle progression. HOTAIR reduction induced colony formation suppression, cell cycle G0/G1 arrest, and orthotopic tumor growth inhibition.

CONCLUSION

Our data establish that HOTAIR is an important long noncoding RNA that primarily serves as a prognostic factor for glioma patient survival, as well as a biomarker for identifying glioma molecular subtypes, a critical regulator of cell cycle progression.

NF-κB-mediated inflammation leading to EMT via miR-200c is involved in cell transformation induced by cigarette smoke extract

Cigarette smoking constitutes a major human health hazard because it is the most important risk factor for lung cancer. Although evidence for smoking-induced lung cancer in humans is strong, the molecular mechanisms by which smoking causes cancer remain to be established. In this investigation, we evaluated the roles of inflammation and the epithelial-mesenchymal transition (EMT) in cigarette smoke extract (CSE)-induced transformation of human bronchial epithelial (HBE) cells. The results showed that chronic exposure to CSE induced EMT and transformation of these cells. Activation of nuclear factor-κB (NF-κB) by CSE increased levels of the proinflammatory interleukin-6 (IL-6), and acute and chronic exposures to CSE caused decreases in miR-200c levels. By blocking NF-κB with Bay11-7082 and IL-6 with anti-IL-6 antibody and enhancement of IL-6 with human recombinant IL-6, we found that the NF-κB signal pathway was involved in CSE-induced increases of IL-6, which suppressed miR-200c expression and promoted EMT. Moreover, IL-6 was necessary for maintenance of CSE-induced transformation and for malignant progression of HBE cells. Finally, blocking of NF-κB with Bay11-7082 prevented CSE-induced EMT and malignant transformation due to decreases of E-cadherin and miR-200c and elevations of IL-6, N-cadherin, and vimentin. Thus, we have defined a link between inflammation and EMT, processes involved in the malignant transformation of cells caused by CSE. This link, mediated through miRNAs, establishes a mechanism for CSE-induced lung carcinogenesis.

MicroRNA-221 mediates the effects of PDGF-BB on migration, proliferation, and the epithelial-mesenchymal transition in pancreatic cancer cells

The platelet-derived growth factor (PDGF) signaling pathway has been found to play important roles in the development and progression of human cancers by regulating the processes of cell proliferation, apoptosis, migration, invasion, metastasis, and the acquisition of the epithelial-mesenchymal transition (EMT) phenotype. Moreover, PDGF signaling has also been found to alter the expression profile of miRNAs, leading to the reversal of EMT phenotype. Although the role of miRNAs in cancer has been documented, there are very few studies documenting the cellular consequences of targeted re-expression of specific miRNAs. Therefore, we investigated whether the treatment of human pancreatic cancer cells with PDGF could alter the expression profile of miRNAs, and we also assessed the cellular consequences. Our study demonstrates that miR-221 is essential for the PDGF-mediated EMT phenotype, migration, and growth of pancreatic cancer cells. Down-regulation of TRPS1 by miR-221 is critical for PDGF-mediated acquisition of the EMT phenotype. Additionally, the PDGF-dependent increase in cell proliferation appears to be mediated by inhibition of a specific target of miR-221 and down-regulation of p27Kip1.

The rejuvenated scenario of epithelial-mesenchymal transition (EMT) and cancer metastasis

The molecular mechanisms underlying cancer progression and metastasis are still poorly understood. In recent years, the epithelial-to-mesenchymal transition (EMT), a traditional phenomenon revealed in embryonic development, has been gradually accepted as a potential mechanism underlying cancer progression and metastasis. Many cell signaling pathways involved in development have been shown to contribute to EMT. An increasing number of genetic and epigenetic elements have been discovered, and their cross-talk relationship in EMT remains to be explored. In addition, accumulating experimental evidence suggests that EMT plays a critical role in different aspects of cancer progression, such as metastasis, stem cell traits, and chemoresistance. However, there are some disagreements and debate about these studies, which raise critical questions worthy of further investigation. Solving these questions will lead to a more complete understanding of cancer metastasis. Due to the close relationship of EMT to cancer metastasis and chemoresistance, targeting EMT or reversing EMT is likely to lead to novel therapeutic approaches for the treatment of human cancers.

The proto-oncogene TWIST1 is regulated by microRNAs

Upregulation of the proto-oncogene Twist1 is highly correlated with acquired drug resistance and poor prognosis in human cancers. Altered expression of this multifunctional transcription factor is also associated with inherited skeletal malformations. The mammalian Twist1 3′UTRs are highly conserved and contain a number of potential regulatory elements including miRNA target sites. We analyzed the translational regulation of TWIST1 using luciferase reporter assays in a variety of cell lines. Among several miRNAs tested, miR-145a-5p, miR-151-5p and a combination of miR-145a-5p + miR-151-5p and miR-151-5p + miR-337-3p were able to significantly repress Twist1 translation. This phenomena was confirmed with both exogenous and endogenous miRNAs and was dependent on the presence of the predicted target sites in the 3′UTR. Furthermore, the repression was sensitive to LNA-modified miRNA antagonists and resulted in decreased migratory potential of murine embryonic fibroblast cells. Understanding the in vivo mechanisms of this oncogene's regulation might open up a possibility for therapeutic interference by gene specific cancer therapies.

Long Noncoding RNAs: Insights from Biological Features and Functions to Diseases

Over the past decade, genome-wide transcriptomic studies have shown that the mammalian genome is pervasively transcribed and produces many thousands of transcriptomes without bias from previous genome annotations. This finding, together with the discovery of a plethora of unexpected RNAs that have no obvious coding capacities, have challenged the traditional views that proteins are the main protagonists of cellular functions and that RNA is merely an intermediary between DNA sequence and its encoded protein. There are many different kinds of products that are generated by this pervasive transcription; this review focuses on long noncoding RNAs (lncRNAs) that have shown spatial and temporal specific patterns of expression and regulation in a wide variety of cells and tissues, adding significant complexity to the understanding of their biological roles. Recent research has shed new light onto the biological function significance of lncRNAs. Here, we review the rapidly advancing field of lncRNAs, describing their biological features and their roles in regulation of gene expression. Moreover, we highlight some recent advances in our understanding of ncRNA-mediated regulation of stem cell pluripotency, morphogenesis, and development, focusing mainly on the regulatory roles of lncRNAs. Finally, we consider the potential medical implications, and the potential use of lncRNAs in drug development and discovery and in the identification of molecular markers of diseases, including cancer.

MicroRNAs in human cancer

Mature microRNAs (miRNAs) are single-stranded RNA molecules of 20-23-nucleotide (nt) length that control gene expression in many cellular processes. These molecules typically reduce the translation and stability of mRNAs, including those of genes that mediate processes in tumorigenesis, such as inflammation, cell cycle regulation, stress response, differentiation, apoptosis, and invasion. miRNA targeting is initiated through specific base-pairing interactions between the 5' end ("seed" region) of the miRNA and sites within coding and untranslated regions (UTRs) of mRNAs; target sites in the 3' UTR lead to more effective mRNA destabilization. Since miRNAs frequently target hundreds of mRNAs, miRNA regulatory pathways are complex. To provide a critical overview of miRNA dysregulation in cancer, we first discuss the methods currently available for studying the role of miRNAs in cancer and then review miRNA genomic organization, biogenesis, and mechanism of target recognition, examining how these processes are altered in tumorigenesis. Given the critical role miRNAs play in tumorigenesis processes and their disease specific expression, they hold potential as therapeutic targets and novel biomarkers.