MicroRNAs: critical regulators of epithelial to mesenchymal (EMT) and mesenchymal to epithelial transition (MET) in cancer progression

miR-147b mediated suppression of DUSP8 promotes lung cancer progression

Dual-specificity phosphatase 8 (DUSP8) plays an important role as a selective c-Jun N-terminal kinase (JNK) phosphatase in mitogen-activated protein kinase (MAPK) signaling. In this study, we found that DUSP8 is silenced by miR-147b in patients with lung adenocarcinoma (LUAD), which correlates with poor overall survival. Overexpression of DUSP8 resulted in a tumor-suppressive phenotype in vitro and in vivo experimental models, whereas silencing DUSP8 with a siRNA approach abrogated the tumor-suppressive properties. We found that miR-147b is a posttranscriptional regulator of DUSP8 that is highly expressed in patients with LUAD and is associated with lower survival. NanoString analysis revealed that the MAPK signaling pathway is mainly affected by overexpression of miR-147b, leading to increased proliferation and migration and decreased apoptosis in vitro. Moreover, induction of miR-147b promotes tumor progression in vitro and in vivo experimental models. Knockdown of miR-147b restored DUSP8, decreased tumor progression in vitro, and increased apoptosis via JNK phosphorylation. These results suggest that miR-147b plays a key role in regulating MAPK signaling in LUAD. The link between DUSP8 and miR-147b may provide novel approaches for the treatment of lung cancer.

Cancer Stemness/Epithelial-Mesenchymal Transition Axis Influences Metastasis and Castration Resistance in Prostate Cancer: Potential Therapeutic Target

Prostate cancer (PCa) is a leading cause of cancer death in men, worldwide. Mortality is highly related to metastasis and hormone resistance, but the molecular underlying mechanisms are poorly understood. We have studied the presence and role of cancer stem cells (CSCs) and the Epithelial-Mesenchymal transition (EMT) in PCa, using both in vitro and in vivo models, thereby providing evidence that the stemness-mesenchymal axis seems to be a critical process related to relapse, metastasis and resistance. These are complex and related processes that involve a cooperative action of different cancer cell subpopulations, in which CSCs and mesenchymal cancer cells (MCCs) would be responsible for invading, colonizing pre-metastatic niches, initiating metastasis and an evading treatments response. Manipulating the stemness-EMT axis genes on the androgen receptor (AR) may shed some light on the effect of this axis on metastasis and castration resistance in PCa. It is suggested that the EMT gene SNAI2/Slug up regulates the stemness gene Sox2, and vice versa, inducing AR expression, promoting metastasis and castration resistance. This approach will provide new sight about the role of the stemness-mesenchymal axis in the metastasis and resistance mechanisms in PCa and their potential control, contributing to develop new therapeutic strategies for patients with metastatic and castration-resistant PCa.

Review article epithelial to mesenchymal transition‑associated microRNAs in breast cancer

Despite major advances, breast cancer (BC) is the most commonly diagnosed carcinoma and remains a deadly disease among women worldwide. Many researchers point toward an important role of an epithelial to mesenchymal transition (EMT) in BC development and promoting metastasis. Here, will be discussed that how functional changes of transcription factors, signaling pathways, and microRNAs (miRNA) in BC promote EMT. A thorough understanding the EMT biology can be important to determine reversing the process and design treatment approaches. There are frequent debates as to whether EMT is really relevant to BC in vivo, in which due to the intrinsic heterogeneity and tumor microenvironment. Nevertheless, given the importance of EMT in cancer progression and metastasis, the implementation of therapies against cancer-associated EMT will continue to help us develop and test potential treatments.

Metastasis Inhibition by Cell Type Specific Expression of BRMS1 Gene under The Regulation of miR200 Family Response Elements

Objective

Specific expression of therapeutic genes in cancer therapy has been per used for many years. One of the innovative strategies that have recently been introduced is employing miRNA response elements (MREs) of microRNAs (whose expression are reduced or inhibited in cancerous cells) into the 3´UTR of the therapeutic genes for their specific expression. Accordingly, MREs of anti-metastatic miRNA family have been used in 3´UTR of the metastasis suppressor gene in the corresponding cells to evaluate the level of metastatic behavior.

Material and Methods

In this experimental study, 3´UTR of the ZEB1 gene with 592 bp length, encompassing multiple MREs of miR-141, miR-429, miR-200b and miR-200c, was employed to replace BRMS1 3´UTR. The obtained vector was then assessed in the context of MCF-10A, MDA-MB231 and MCF-7 cells.

Results

It was shown that the employed MREs are able to up-regulate BRMS expression in the metastatic MDA- MB231 cells (almost 3.5-fold increase), while it was significantly reduced within tumorigenic/non-metastatic MCF-7 cells. Specific expression of BRMS1 in metastatic cells led to a significant reduction in their migratory and invasive characteristics (about 65% and 55%, respectively). Two-tailed student’s t test was utilized for statistical analysis.

Conclusion

It was demonstrated that a chimeric vector containing BRMS1 which is regulated by miR-200 family response element may represent a promising therapeutic tool. This is due to the capability of the chimeric vector for cell type-specific expression of anti-metastatic genes with lowest side-effects. It consequently prohibits the invasive characteristics of metastatic cells.

What we can learn from embryos to understand the mesenchymal-to-epithelial transition in tumor progression

Epithelial plasticity involved the terminal and transitional stages that occur during epithelial-to-mesenchymal transition (EMT) and mesenchymal-to-epithelial transition (MET), both are essential at different stages of early embryonic development that have been co-opted by cancer cells to undergo tumor metastasis. These processes are regulated at multiple instances, whereas the post-transcriptional regulation of key genes mediated by microRNAs is gaining major attention as a common and conserved pathway. In this review, we focus on discussing the latest findings of the cellular and molecular basis of the less characterized process of MET during embryonic development, with special attention to the role of microRNAs. Although we take in consideration the necessity of being cautious when extrapolating the obtained evidence, we propose some commonalities between early embryonic development and cancer progression that can shed light into our current understanding of this complex event and might aid in the design of specific therapeutic approaches.

MicroRNA-200c Prevents Progress of Cutaneous Squamous Cell Carcinoma by Targeting Tyrosine-Protein Kinase Fyn (FYN)

Cutaneous squamous cell carcinoma (cSCC), a malignant skin tumor, begins in the epidermis and the keratinocytes of the skin appendages. However, the cause remains unclear. MicroRNA-200c (miR-200c), a key modulator of epithelial-to-mesenchymal transition (EMT), has been reported to act as an anticancer gene in a variety of cancers. However, its role and partial mechanism in cSCC remain undetermined. The results of this study showed depleted levels of miR-200c in cSCC tissues. Its suppressive effects on cell proliferation, and motility, as well as its apoptosis-promoting effect, were observed in the A-431 cells. Additionally, immunofluorescence and qRT-PCR assays revealed that FYN acted as a direct target of miR-200c, and FYN knockdown exerted had similar impact as that of miR-200c overexpression, including increased cellular apoptosis and decreased cellular growth. These results emphasized the onco-suppressive nature of miR-200c, which was evident based on its interaction with FYN in cSCC. This finding could have potential benefits in developing cSCC therapy.

Mesenchymal-Epithelial Transition in Fibroblasts of Human Normal Lungs and Interstitial Lung Diseases

In passages above ten and growing very actively, we observed that some human lung fibroblasts cultured under standard conditions were transformed into a lineage of epithelial-like cells (ELC). To systematically evaluate the possible mesenchymal–epithelial transition (MET) occurrence, fibroblasts were obtained from normal lungs and also from lungs affected by idiopathic interstitial diseases. When an unusual epithelial-like phenotypic change was observed, cultured cells were characterized by confocal immunofluorescence microscopy, immunoblotting, immunocytochemistry, cytofluorometry, gelatin zymography, RT-qPCR, and hybridization in a whole-transcript human microarray. Additionally, microvesicles fraction (MVs) from ELC and fibroblasts were used to induce MET, while the microRNAs (miRNAs) contained in the MVs were identified. Pattern-gene expression of the original fibroblasts and the derived ELC revealed profound changes, upregulating characteristic epithelial-cell genes and downregulating mesenchymal genes, with a marked increase of E-cadherin, cytokeratin, and ZO-1, and the loss of expression of α-SMA, collagen type I, and Thy-1 cell surface antigen (CD90). Fibroblasts, exposed to culture media or MVs from the ELC, acquired ELC phenotype. The miRNAs in MVs shown six expressed exclusively in fibroblasts, and three only in ELC; moreover, twelve miRNAs were differentially expressed between fibroblasts and ELC, all of them but one was overexpressed in fibroblasts. These findings suggest that the MET-like process can occur in human lung fibroblasts, either from normal or diseased lungs. However, the biological implication is unclear.

MicroRNA-15a-5p inhibits endometrial carcinoma proliferation, invasion and migration via downregulation of VEGFA and inhibition of the Wnt/β-catenin signaling pathway

Endometrial carcinoma (EC) is one of the most common malignant gynecological tumors. Dysregulation of microRNAs (miRNAs/miRs) is frequently identified in human tumors, playing key regulatory roles in tumor growth and metastasis. The present study aimed to explore the functions and potential mechanisms of miR-15a-5p in EC progression. RT-qPCR was used to detect the expression levels of miR-15a-5p and vascular endothelial growth factor A (VEGFA) mRNA. Western blot analysis was performed to examine the expression of related proteins. Functional assays, including proliferation and Transwell assays were performed to determine the roles of miR-15a-5p in EC progression. TargetScan and luciferase reporter assays were used to explore the potential target genes of miR-15a-5p. The results revealed that miR-15a-5p was underexpressed in EC tissue samples in comparison with that in matched normal tissue samples. The expression level of miR-15a-5p was associated with the clinicopathologic characteristics of EC patients. Notably, both in vitro and in vivo assays revealed that miR-15a-5p upregulation significantly inhibited EC growth and metastasis. Furthermore, bioinformatics analysis and dual luciferase reporter assay indicated that VEGFA was a candidate target of miR-15a-5p. Mechanistic investigation revealed that miR-15a-5p inhibited EC development via regulation of Wnt/β-catenin pathway and targeting of VEGFA. In summary, the present results demonstrated that miR-15a-5p could inhibit EC development and may serve as a promising therapeutic biomarker in EC.

Microfluidic System to Analyze the Effects of Interleukin 6 on Lymphatic Breast Cancer Metastasis

Metastasis is the primary cause of a large number of cancer-associated deaths. By portraying the precise environment of the metastasis process in vitro, the microfluidic system provides useful insights on the mechanisms underlying cancer cell migration, invasion, colonization, and the procurement of supplemental nutrients. However, current in vitro metastasis models are biased in studying blood vessel-based metastasis pathways and thus the understanding of lymphatic metastasis is limited which is also closely related to the inflammatory system. To understand the effects of inflammatory cytokines in lymphatic metastasis, we developed a three-channel microfluidic system by mimicking the lymph vessel-tissue-blood vessel (LTB) structure. Based on the LTB chip, we successfully confirmed the inflammatory cytokine, interleukin 6 (IL-6), -mediated intercellular communication in the tumor microenvironment during lymphatic metastasis. The IL-6 exposure to different subtypes of breast cancer cells was induced epithelial-mesenchymal transition (EMT) and improved tissue invasion property (8-fold). And the growth of human vein endothelial cells toward the lymph vessel channel was observed by VEGF secretion from human lymphatic endothelial cells with IL-6 treatment. The proposed LTB chip can be applied to analyze the intercellular communication during the lymphatic metastasis process and be a unique tool to understand the intercellular communication in the cancer microenvironment under various extracellular stimuli such as inflammatory cytokines, stromal reactions, hypoxia, and nutrient deficiency.

Cardiac Regeneration and Tumor Growth-What Do They Have in Common?

Acute myocardial infarction is a leading cause of death. Unlike most adult mammals, zebrafish have the capability to almost fully regenerate their hearts after injury. In contrast, ischemic damage in adult human and mouse hearts usually results in scar tissue. mRNA-Sequencing (Seq) and miRNA-Seq analyses of heart regeneration in zebrafish over time showed that the process can be divided into three phases: the first phase represents dedifferentiation and proliferation of cells, the second phase is characterized by migration, and in the third phase cell signals indicate heart development and differentiation. The first two phases seem to share major similarities with tumor development and growth. To gain more insight into these similarities between cardiac regeneration and tumor development and growth, we used patient matched tumor normal (“healthy”) RNA-Seq data for several tumor entities from The Cancer Genome Atlas (TCGA). Subsequently, RNA data were processed using the same pipeline for both the zebrafish samples and tumor datasets. Functional analysis showed that multiple Gene Ontology terms (GO terms) are involved in both early stage cardiac regeneration and tumor development/growth across multiple tumor entities. These GO terms are mostly associated with cell cycle processes. Further analysis showed that orthologous genes are the same key players that regulated these changes in both diseases. We also observed that GO terms associated with heart development in the third late phase of cardiac regeneration are downregulated in the tumor entities. Taken together, our analysis illustrates similarities between cardiac remodeling and tumor progression.

TRANSICIÓN EPITELIO-MESÉNQUIMA INDUCIDA POR VIRUS

La Transición Epitelio-Mesénquima (EMT) es un proceso de dediferenciación altamente conservado en vertebrados. Este ocurre en células epiteliales con la activación progresiva de la pérdida de la polaridad, la adquisición de motilidad individual y la capacidad invasiva a otros tejidos. La EMT es un proceso normal durante el desarrollo; no obstante, en condiciones patológicas está relacionada con la inducción de metástasis, lo cual representa una vía alterna al desarrollo de procesos oncogénicos tempranos. Aunque la EMT es activada principalmente por factores de crecimiento, también se puede desencadenar por infecciones de patógenos intracelulares mediante la activación de rutas moleculares inductoras de este proceso. Por lo tanto, una infección bacteriana o viral pueda generar predisposición al desarrollo de tumores. Nuestro interés está enfocado principalmente encaracterizar la relación virus-hospedero, y en el caso de los virus, varios ya se han descrito como inductores de la EMT. En este artículo de revisión se describenelfenómeno de la plasticidad celular y la ocurrencia detallada del proceso de EMT, los patógenos virales reportados como inductores, los mecanismos moleculares usados para ello y las vías de regulación mediante miRNAs. Por último, se discute cómo esta relación virus-hospedero puede explicar la patogénesis de la enfermedad causada por Dengue virus, favoreciendo la identificación de blancos moleculares para terapia, estrategia conocida como Antivirales dirigidos a blancos celulares o HTA (Host-targeting antivirals).

Current Strategies for Treating NSCLC: From Biological Mechanisms to Clinical Treatment

The identification of specific epidermal growth factor receptor (EGFR)-activating mutations heralded a breakthrough in non-small-cell lung cancer (NSCLC) treatments, with the subsequent development of EGFR-tyrosine kinase inhibitor (TKIs) becoming the first-line therapy for patients harboring EGFR mutations. However, acquired resistance to EGFR-TKIs inevitably occurs in patients following initial TKI treatment, leading to disease progression. Various mechanisms are behind the acquired resistance, and mainly include (1) target gene modification, (2) alternative parallel pathway activation, (3) downstream pathway activation, and (4) histological/phenotypic transformation. Approaches to combat the acquired resistance have been investigated according to these mechanisms. Newer generations of TKIs have been developed to target the secondary/tertiary EGFR mutations in patients with acquired resistance. In addition, combination therapies have been developed as another promising strategy to overcome acquired resistance through the activation of other signaling pathways. Thus, in this review, we summarize the mechanisms for acquired resistance and focus on the potential corresponding therapeutic strategies for acquired resistance.

ADAR1-Dependent RNA Editing Promotes MET and iPSC Reprogramming by Alleviating ER Stress

RNA editing of adenosine to inosine (A to I) is catalyzed by ADAR1 and dramatically alters the cellular transcriptome, although its functional roles in somatic cell reprogramming are largely unexplored. Here, we show that loss of ADAR1-mediated A-to-I editing disrupts mesenchymal-to-epithelial transition (MET) during induced pluripotent stem cell (iPSC) reprogramming and impedes acquisition of induced pluripotency. Using chemical and genetic approaches, we show that absence of ADAR1-dependent RNA editing induces aberrant innate immune responses through the double-stranded RNA (dsRNA) sensor MDA5, unleashing endoplasmic reticulum (ER) stress and hindering epithelial fate acquisition. We found that A-to-I editing impedes MDA5 sensing and sequestration of dsRNAs encoding membrane proteins, which promote ER homeostasis by activating the PERK-dependent unfolded protein response pathway to consequently facilitate MET. This study therefore establishes a critical role for ADAR1 and its A-to-I editing activity during cell fate transitions and delineates a key regulatory layer underlying MET to control efficient reprogramming.

ZEB1: A Critical Regulator of Cell Plasticity, DNA Damage Response, and Therapy Resistance

The predominant way in which conventional chemotherapy kills rapidly proliferating cancer cells is the induction of DNA damage. However, chemoresistance remains the main obstacle to therapy effectivity. An increasing number of studies suggest that epithelial-to-mesenchymal transition (EMT) represents a critical process affecting the sensitivity of cancer cells to chemotherapy. Zinc finger E-box binding homeobox 1 (ZEB1) is a prime element of a network of transcription factors controlling EMT and has been identified as an important molecule in the regulation of DNA damage, cancer cell differentiation, and metastasis. Recent studies have considered upregulation of ZEB1 as a potential modulator of chemoresistance. It has been hypothesized that cancer cells undergoing EMT acquire unique properties that resemble those of cancer stem cells (CSCs). These stem-like cells manifest enhanced DNA damage response (DDR) and DNA repair capacity, self-renewal, or chemoresistance. In contrast, functional experiments have shown that ZEB1 induces chemoresistance regardless of whether other EMT-related changes occur. ZEB1 has also been identified as an important regulator of DDR by the formation of a ZEB1/p300/PCAF complex and direct interaction with ATM kinase, which has been linked to radioresistance. Moreover, ATM can directly phosphorylate ZEB1 and enhance its stability. Downregulation of ZEB1 has also been shown to reduce the abundance of CHK1, an effector kinase of DDR activated by ATR, and to induce its ubiquitin-dependent degradation. In this perspective, we focus on the role of ZEB1 in the regulation of DDR and describe the mechanisms of ZEB1-dependent chemoresistance.

Cancer stem cell and mesenchymal cell cooperative actions in metastasis progression and hormone resistance in prostate cancer: Potential role of androgen and gonadotropin‑releasing hormone receptors (Review)

Prostate cancer (PCa) is the leading cause of male cancer‑associated mortality worldwide. Mortality is associated with metastasis and hormone resistance. Cellular, genetic and molecular mechanisms underlying metastatic progression and hormone resistance are poorly understood. Studies have investigated the local effects of gonadotropin‑releasing hormone (GnRH) analogs (used for androgen deprivation treatments) and the presence of the GnRH receptor (GnRH‑R) on PCa cells. Furthermore, cell subpopulations with stem‑like properties, or cancer stem cells, have been isolated and characterized using a cell culture system derived from explants of human prostate tumors. In addition, the development of preclinical orthotopic models of human PCa in a nonobese diabetic/severe combined immunodeficiency mouse model of compromised immunity has enabled the establishment of a reproducible system of metastatic progression in vivo. There is increasing evidence that metastasis is a complex process involving the cooperative actions of different cancer cell subpopulations, in which cancer stem‑like cells would be responsible for the final step of colonizing premetastatic niches. It has been hypothesized that PCa cells with stemness and mesenchymal signatures act cooperatively in metastatic progression and the inhibition of stemness genes, and that overexpression of androgen receptor (AR) and GnRH‑R decreases the rate the metastasis and sensitizes tumors to hormone therapy. The aim of the present review is to analyze the evidence regarding this cooperative process and the possible influence of stem‑like cell phenotypes, AR and GnRH‑R in metastatic progression and hormone resistance. These aspects may represent an important contribution in the understanding of the mechanisms underlying metastasis and hormone resistance in PCa, and potential routes to blocking these processes, enabling the development of novel therapies that would be particularly relevant for patients with metastatic and castration‑resistant PCa.

Magnolol Suppresses TGF-β-Induced Epithelial-to-Mesenchymal Transition in Human Colorectal Cancer Cells

Tumor metastasis is the end state of a multistep process that includes dissemination of tumor cells to distant organs and requires tumor cells to adapt to different tissue microenvironments. During metastasis, tumor cells undergo a morphological change known as transdifferentiation or the epithelial-to-mesenchymal transition (EMT). In normal embryonic development, the EMT occurs in the context of morphogenesis in a variety of tissues. Over the course of this process, epithelial cells lose their cell-cell adhesion and polarity properties. In this study, we investigated whether magnolol could suppress the EMT in human colorectal cancer cells. To this end, we examined the epithelial markers E-cadherin, ZO-1, and claudin and the mesenchymal markers N-cadherin, TWIST1, Slug, and Snail. Magnolol effectively inhibited EMT in human colon cancer cell lines by upregulating epithelial markers and downregulating mesenchymal markers. The EMT is induced by the TGF-β signaling pathway. To determine whether magnolol disrupts TGF-β signaling, we examined several mediators of this pathway, and found that magnolol decreased the levels of phosphorylated (i.e., active) ERK, GSK3β, and Smad. We conclude that magnolol blocks migration in HCT116 cells by suppressing TGF-β signaling.

MicroRNA-200c-3p/ZEB2 loop plays a crucial role in the tumor progression of prostate carcinoma

Background

The microRNA (miRNA) miR-200c-3p is involved in the tumorigenesis and progression of a variety of cancers. However, the underlying regulatory role of miR-200c-3p in prostate cancer (PCa) remains unclear.

Methods

Online databases including Oncomine, Linkedomics and StarBase were used to investigate the clinical significance of miR-200c-3p, along with associated gene targets. PCa tissues and adjacent normal tissues were used for the detection of miR-200c-3p expression. A lentivirus overexpressing miR-200c-3p was constructed and transfected into PC3 and DU145 cells. Cell formation of proliferation, migration, and invasion were determined by cell viability and colony-formation assay, wound healing assay, and Matrigel invasion assay, respectively. Epithelial-mesenchymal transition (EMT)-associated markers were determined by qRT-PCR and Western blot. A luciferase reporter assay was performed to determine the direct relationship of miR-200c-3p and ZEB2. The tumor-suppressive role of miR-200c-3p was further confirmed by a xenograft tumor model and immunohistochemical (IHC) staining.

Results

Online database analyses showed that miR-200c-3p was associated with pathologic T and N stage in PCa, and miR-200c-3p was downregulated in PCa tissues. Overexpression of miR-200c-3p was considered a tumor suppressor and was found to significantly suppress the formation of migration and invasion in PCa cells via repression of E-cadherin-induced EMT. The bioinformatic database indicated that ZEB2 has a significant correlation with miR-200c-3p and was upregulated in PCa tissues. Further, ZEB2 expression was suppressed by the upregulation of miR-200c-3p and was identified as a direct target of miR-200c-3p. In addition, repression of ZEB2 could restore the levels of miR-200c-3p in PCa cells in turn, suggesting a potential negative loop between miR-200c-3p and ZEB2. miR-200c-3p also had an antitumor effect by negatively regulating ZEB2 in a xenograft mouse model.

Conclusions

Taken together, the results of our study demonstrated the novel regulatory loop of miR-200c-3/ZEB2 in PCa progression, providing effective therapeutic strategies for PCa in the future.

Overview on Epigenetic Re-programming: A Potential Therapeutic Intervention in Triple Negative Breast Cancers

Breast cancer treatments leads to variable responses. Hormonal therapy is beneficial to receptor positive breast cancer subtypes and display better clinical outcome than triple negative breast cancers (TNBCs) with FEC (5-Fluorouracil, Epirubicin and Cyclophosphamide) the mainstay chemotherapy regiment. Owning to their negative expressions of estrogen (ER), progesterone (PR) and HER2 receptors, disease recurrence and metastasis befalls some patients indicating resistance to FEC. Involvement of epigenetic silencing through DNA methylation, histone methylation, acetylation and sumoylation may be the key player in FEC chemoresistance. Epigenetic and molecular profiling successfully classified breast cancer subtypes, indicating potential driver mechanisms to the progression of TNBCs but functional mechanisms behind chemoresistance of these molecular markers are not well defined. Several epigenetic inhibitors and drugs have been used in the management of cancers but these attempts are mainly beneficial in hematopoietic cancers and not specifically favourable in solid tumours. Hypothetically, upon administration of epigenetic drugs, recovery of tumour suppressor genes is expected. However, high tendency of switching on global metastatic genes is predicted. Polycomb repressive complex (PRC) such as EZH2, SETD1A, DNMT, is known to have repressive effects in gene regulation and shown to inhibit cell proliferation and invasion in breast cancers. Individual epigenetic regulators may be an option to improve chemo-drug delivery in cancers. This review discussed on molecular signatures of various breast cancer subtypes and on-going attempts in understanding underlying molecular mechanisms of epigenetic regulators as well as providing insights on possible ways to utilize epigenetic enzymes/inhibitors with responses to chemotherapeutic drugs to re-program cellular and biological outcome in TNBCs.

Association between sunlight exposure and risk of age-related macular degeneration: a meta-analysis

Background

A substantial number of epidemiological studies have investigated the possible associations between sunlight exposure and Age-related Macular Degeneration (AMD), but the results from studies are inconsistent. The aim of this meta-analysis was to evaluate the association between sunlight exposure and the risk of AMD.

Methods

Relevant studies were searched using databases including PubMed, EMBASE, and Web of Science database. Two authors independently extracted data and assessed study quality. The random-effects model was used to calculate the pooled covariates-adjusted odds ratio (OR). Subgroup analyses based on study design, stage of AMD, method of exposure assessment, and study latitude were carried out. The heterogeneity across the studies was tested, as was publication bias.

Results

Fourteen eligible studies including 43,934 individuals based on the inclusion criteria were analyzed. The pooled OR for sunlight exposure and AMD was 1.10 (95% CI = 0.98–1.23). In addition, similar insignificant results were observed in further subgroup analyses based on stage of AMD, method of exposure assessment, and study latitude. Sun-avoidance behavior did not decrease the risk of AMD (OR = 1.12, 95% CI = 0.76–1.67). Moderate heterogeneity was observed in most of analyses.

Conclusion

The results indicate that sunlight exposure may not be associated with increased risk of AMD based on current published data.

The Epigenetic Regulation of HCC Metastasis

Epigenetic alterations, such as histone modification, DNA methylation, and miRNA-mediated processes, are critically associated with various mechanisms of proliferation and metastasis in several types of cancer. To overcome the side effects and limited effectiveness of drugs for cancer treatment, there is a continuous need for the identification of more effective drug targets and the execution of mechanism of action (MOA) studies. Recently, epigenetic modifiers have been recognized as important therapeutic targets for hepatocellular carcinoma (HCC) based on their reported abilities to suppress HCC metastasis and proliferation in both in vivo and in vitro studies. Therefore, here, we introduce epigenetic modifiers and alterations related to HCC metastasis and proliferation, and their molecular mechanisms in HCC metastasis. The existing data suggest that the study of epigenetic modifiers is important for the development of specific inhibitors and diagnostic targets for HCC treatment.

MicroRNA-183 induces epithelial-mesenchymal transition and promotes endometrial cancer cell migration and invasion in by targeting CPEB1

The aim of this study is to evaluate the ability of microRNA-183 (miR-183) to influence epithelial-mesenchymal transition (EMT) and cell proliferation, migration, invasion, and apoptosis in endometrial cancer (EC) by targeting cytoplasmic polyadenylation element binding protein 1(CPEB1). EC tissues with matched nonmalignant tissues were collected from 208 EC patients. Ishikawa and RL95-2 cells were selected for cell experiments in vitro and each kind of cells were grouped into blank, negative control (NC), miR-183 mimic, miR-183 inhibitor, CPEB1 overexpression, and miR-183 mimic + CPEB1 overexpression groups. Expressions of miR-183, CPEB1, E-cadherin, and Vimentin were determined by reverse transcription quantitative polymerase chain reaction (RT-qPCR) and Western blotting. Cell viability, colony formation ability, migration, invasion, and apoptosis were assessed by MTT assay, clone formation assay, scratch test, Transwell assay, and flow cytometry. In vivo tumorigenesis of Ishikawa cells was evaluated by tumor formation in nude mice. The miR-183 expression was higher, but the CPEB1 expression was lower in EC tissues than in adjacent nonmalignant tissues. CPEB1 was confirmed as the target of miR-183 by dual-luciferase reporter assay. The miR-183 mimic group had increased cell viability, colony formation ability, cell invasion and migration, tumor volume and weight in nude mice, but decreased cell apoptosis when compared with the blank group. The expression of E-cadherin was down-regulate, but expression of Vimentin was up-regulate in the miR-183 mimic group in comparison with the blank group. In terms of a comparison between the blank group and CPEB1 overexpression group, the CPEB1 overexpression group had suppressed cell viability, colony formation ability, cell invasion and migration, tumor volume and weight, but increased cell apoptosis. The expression of E-cadherin was up-regulated, but the expression of Vimentin was down-regulated in the CPEB1 overexpression group in comparison with the blank group. The miR-183 mimic + CPEB1 overexpression group had higher miR-183 expression than the blank group. These findings indicate that miR-183 induces EMT, inhibits apoptosis, and promotes cell proliferation, migration, invasion, and in vivo tumorigenesis in EC by targeting CPEB1.

Effect of simvastatin and microRNA-21 inhibitor on metastasis and progression of human salivary adenoid cystic carcinoma

Salivary adenoid cystic carcinoma (SACC) is a common malignancy of the salivary glands. Epithelial-mesenchymal transition (EMT) and P53 signaling pathway are associated with SACC metastasis and progression. Although simvastatin (SIM) is effective against the growth of many cancer types, its side effects limit its use. microRNA-21 (miR-21) is highly expressed in a variety of tumors and has a role in promoting tumor development. Therefore, the aim of the present study was to evaluate the effect of SIM in combination with miR-21 inhibitor (miR-21i) against lung metastatic SACC cells (SACC-LM). Our results showed that miR-21i was effective in reducing the resistance of SACC-LM to SIM, resulting in SACC-LM acquisition of epithelial traits, cell migration and invasion reduction, growth inhibition and induction of apoptosis. The expression of proteins associated to metastasis and tumor progression were regulated by the combined use of SIM and miR-21i. Thus, our findings demonstrated that such combination was effective in inhibiting SACC-LM progression, suggesting that multi-target therapy against SACC might represent a potentially successful approach in clinical treatment.

Molecular regulation of epithelial-to-mesenchymal transition in tumorigenesis (Review)

Numerous studies over the past two decades have focused on the epithelial-to-mesenchymal transition (EMT) and its role in the development of metastasis. Certain studies highlighted the importance of EMT in the dissemination of tumor cells and metastasis of epithelium-derived carcinomas. Tumor metastasis is a multistep process during which tumor cells change their morphology, and start to migrate and invade distant sites. The present review discusses the current understanding of the molecular mechanisms contributing to EMT in embryogenesis, fibrosis and tumorigenesis. Additionally, the signaling pathways that initiate EMT through transcriptional factors responsible for the activation and suppression of various genes associated with cancer cell migration were investigated. Furthermore, the important role of the epigenetic modifications that regulate EMT and the reverse process, mesenchymal-to-epithelial transition (MET) are discussed. MicroRNAs are key regulators of various intracellular processes and current knowledge of EMT has significantly improved due to microRNA characterization. Their effect on signaling pathways and the ensuing events that occur during EMT at the molecular level is becoming increasingly recognized. The current review also highlights the role of circulating tumor cells (CTCs) and CTC clusters, and their ability to form metastases. In addition, the biological properties of different types of circulating cells based on their tumor-forming potential are compared.

MicroRNA-30a increases tight junction protein expression to suppress the epithelial-mesenchymal transition and metastasis by targeting Slug in breast cancer

The epithelial-to-mesenchymal (EMT) transition is a prerequisite for conferring metastatic potential during tumor progression. microRNA-30a (miR-30a) expression was significantly lower in aggressive breast cancer cell lines compared with non-invasive breast cancer and non-malignant mammary epithelial cell lines. In contrast, miR-30a overexpression reversed the mesenchymal appearance of cancer cells to result in a cobblestone-like epithelial phenotype. We identified Slug, one of the master regulators of EMT, as a target of miR-30a using in silico prediction. Reporter assays indicated that miR-30a could bind to the 3'-untranslted region of Slug mRNA. Furthermore, we linked miR-30a to increased expression of claudins, a family of tight junction transmembrane proteins. An interaction between Slug and E-box in the claudin promoter sequences was reduced upon miR-30a overexpression, further leading to reduction of filopodia formation and decreased invasiveness/metastasis capabilities of breast cancer cells. Consistently, delivery of miR-30a in xenografted mice decreased tumor invasion and migration. In patients with breast cancer, a significantly elevated risk of the miR-30alow/CLDN2low/FSCNhigh genotype was observed, linking to a phenotypic manifestation of larger tumor size, lymph node metastasis, and advanced tumor stage among patients. In conclusion, the miR-30a/Slug axis inhibits mesenchymal tumor development by interfering with metastatic cancer cell programming and may be a potential target for therapy in breast cancer.

Expression and significance of secreted protein acidic and rich in cysteine in human osteosarcoma

Osteosarcoma is the most common primary malignancy of bone, and is a high-grade malignant mesenchymal tumor with high recurrence and metastatic rates. Increased expression of secreted protein, acidic and rich in cysteine (SPARC) indicates poor prognosis in a number of malignances. However, the expression level of SPARC in human osteosarcoma and its associated mechanism remains unclear. To analyze the expression of SPARC in human osteosarcoma and its potential application in the diagnosis and treatment of osteosarcoma, the clinical records and samples of 20 cases of osteosarcoma were collected. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) analysis applied to detect SPARC expression levels in osteosarcoma tissues, with normal bone tissue as control. Immunofluorescence detection was used to examine the distribution of SPARC. The association between SPARC level and clinical factors was analyzed. RT-qPCR (P=0.002) indicated that the SPARC level in osteosarcoma tissues was significantly increased compared with that in normal tissues. Immunofluorescence detection indicated that SPARC was widely distributed in tumor tissues. SPARC protein expression level was positively associated with lung metastasis (P=0.016). The results indicated that SPARC tends to be highly expressed in human osteosarcoma tissues. The expression level of SPARC is associated with lung metastasis, which may be an indicator of prognosis. Thus, SPARC may be a potential tumor marker and therapeutic target in osteosarcoma.

miR-31 Functions as an Oncomir Which Promotes Epithelial-Mesenchymal Transition via Regulating BAP1 in Cervical Cancer

MicroRNA-31 (miR-31) functions as tumor suppressors or oncogenes that are involved in tumor behavior. However, the function of miR-31 in cervical carcinogenesis remains unclear. The aim of this study was to validate the potential role of miR-31 and BRCA1-associated protein-1 (BAP1) on regulating epithelial-mesenchymal transition (EMT) in cervical cancer. In the present study, qRT-PCR assay revealed that the expression of miR-31 was upregulated in human cervical cancer cells and clinical tissues. Results of wound healing and cell migration assay revealed that knockdown of miR-31 inhibited cell metastasis and migration. Bioinformatic and dual-luciferase reporter gene assay showed that BAP1 was the direct target of miR-31. Furthermore, the results revealed that miR-31 promoted proliferation and EMT in cervical cancer cells and accelerated the development of tumor growth in vivo xenograft experiment by inhibiting BAP1 expression. Overall, these results highlight an important role of miR-31 functioning as an oncomir which could promote EMT in cervical cancer via downregulating BAP1 expression. Thus, downregulation of miR-31 could be a novel approach for the molecular treatment of cervical cancers and other malignancies.

The crosstalk between lncRNA and microRNA in cancer metastasis: orchestrating the epithelial-mesenchymal plasticity

Noncoding RNAs (ncRNAs) have been demonstrated to closely associate with gene regulation and encompass the well-known microRNAs (miRNAs), as well as the most recently acknowledged long noncoding RNAs (lncRNAs). Current evidence indicates that lncRNAs can interact with miRNAs and these interactions play crucial roles in cancer metastasis, through regulating critical events especially the epithelial-mesenchymal transition (EMT). This review summarizes the types of lncRNA-miRNA crosstalk identified to-date and discusses their influence on the epithelial-mesenchymal plasticity and clinical metastatic implication.

Role of Forkhead Box Class O proteins in cancer progression and metastasis

It is now widely accepted that several gene alterations including transcription factors are critically involved in cancer progression and metastasis. Forkhead Box Class O proteins (FoxOs) including FoxO1/FKHR, FoxO3/FKHRL1, FoxO4/AFX and FoxO6 transcription factors are known to play key roles in proliferation, apoptosis, metastasis, cell metabolism, aging and cancer biology through their phosphorylation, ubiquitination, acetylation and methylation. Though FoxOs are proved to be mainly regulated by upstream phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3 K)/Akt signaling pathway, the role of FoxOs in cancer progression and metastasis still remains unclear so far. Thus, with previous experimental evidences, the present review discussed the role of FoxOs in association with metastasis related molecules including cannabinoid receptor 1 (CNR1), Cdc25A/Cdk2, Src, serum and glucocorticoid inducible kinases (SGKs), CXCR4, E-cadherin, annexin A8 (ANXA8), Zinc finger E-box-binding homeobox 2 (ZEB2), human epidermal growth factor receptor 2 (HER2) and mRNAs such as miR-182, miR-135b, miR-499-5p, miR-1274a, miR-150, miR-34b/c and miR-622, subsequently analyzed the molecular mechanism of some natural compounds targeting FoxOs and finally suggested future research directions in cancer progression and metastasis.

Unravelling the complexity of signalling networks in cancer: A review of the increasing role for computational modelling

Cancer induction is a highly complex process involving hundreds of different inducers but whose eventual outcome is the same. Clearly, it is essential to understand how signalling pathways and networks generated by these inducers interact to regulate cell behaviour and create the cancer phenotype. While enormous strides have been made in identifying key networking profiles, the amount of data generated far exceeds our ability to understand how it all "fits together". The number of potential interactions is astronomically large and requires novel approaches and extreme computation methods to dissect them out. However, such methodologies have high intrinsic mathematical and conceptual content which is difficult to follow. This review explains how computation modelling is progressively finding solutions and also revealing unexpected and unpredictable nano-scale molecular behaviours extremely relevant to how signalling and networking are coherently integrated. It is divided into linked sections illustrated by numerous figures from the literature describing different approaches and offering visual portrayals of networking and major conceptual advances in the field. First, the problem of signalling complexity and data collection is illustrated for only a small selection of known oncogenes. Next, new concepts from biophysics, molecular behaviours, kinetics, organisation at the nano level and predictive models are presented. These areas include: visual representations of networking, Energy Landscapes and energy transfer/dissemination (entropy); diffusion, percolation; molecular crowding; protein allostery; quinary structure and fractal distributions; energy management, metabolism and re-examination of the Warburg effect. The importance of unravelling complex network interactions is then illustrated for some widely-used drugs in cancer therapy whose interactions are very extensive. Finally, use of computational modelling to develop micro- and nano- functional models ("bottom-up" research) is highlighted. The review concludes that computational modelling is an essential part of cancer research and is vital to understanding network formation and molecular behaviours that are associated with it. Its role is increasingly essential because it is unravelling the huge complexity of cancer induction otherwise unattainable by any other approach.

Long Non-Coding RNAs: Key Regulators of Epithelial-Mesenchymal Transition, Tumour Drug Resistance and Cancer Stem Cells

Epithelial mesenchymal transition (EMT), the adoption by epithelial cells of a mesenchymal-like phenotype, is a process co-opted by carcinoma cells in order to initiate invasion and metastasis. In addition, it is becoming clear that is instrumental to both the development of drug resistance by tumour cells and in the generation and maintenance of cancer stem cells. EMT is thus a pivotal process during tumour progression and poses a major barrier to the successful treatment of cancer. Non-coding RNAs (ncRNA) often utilize epigenetic programs to regulate both gene expression and chromatin structure. One type of ncRNA, called long non-coding RNAs (lncRNAs), has become increasingly recognized as being both highly dysregulated in cancer and to play a variety of different roles in tumourigenesis. Indeed, over the last few years, lncRNAs have rapidly emerged as key regulators of EMT in cancer. In this review, we discuss the lncRNAs that have been associated with the EMT process in cancer and the variety of molecular mechanisms and signalling pathways through which they regulate EMT, and finally discuss how these EMT-regulating lncRNAs impact on both anti-cancer drug resistance and the cancer stem cell phenotype.

microRNA-802 inhibits epithelial-mesenchymal transition through targeting flotillin-2 in human prostate cancer

miRNAs are a class of non-coding RNAs that exert critical roles in various biological processes. The aim of the present study was to identify the functional roles of miR-802 in regulating epithelial-mesenchymal transition (EMT) in prostate cancer (PCa). miR-802 expression was detected in 73 pairs of PCa samples and PCa cell lines (PC3 and DU145 cells) by qRT-PCR. Cell proliferation was detected using MTT assay, and cell apoptosis was evaluated using flow cytometry. Transwell assay was conducted to investigate cell migration and invasion. Expression analysis of a set of EMT markers was performed to explore whether miR-802 is involved in EMT program. Xenograft model was established to investigate the function of miR-802 in carcinogenesis in vivo The direct regulation of Flotillin-2 (Flot2) by miR-802 was identified using luciferase reporter assay. miR-802 was remarkably down-regulated in PCa tissues and cell lines. Gain-of-function trails showed that miR-802 serves as an 'oncosuppressor' in PCa through inhibiting cell proliferation and promoting cell apoptosis in vitro Overexpression of miR-802 significantly suppressed in vivo PCa tumor growth. Luciferase reporter analysis identified Flot2 as a direct target of miR-802 in PCa cells. Overexpressed miR-802 significantly suppressed EMT, migration and invasion in PCa cells by regulating Flot2. We identified miR-802 as a novel tumor suppressor in PCa progression and elucidated a novel mechanism of the miR-802/Flot2 axis in the regulation of EMT, which may be a potential therapeutic target.

Epithelial-mesenchymal-transition regulators in prostate cancer: Androgens and beyond

Castration resistant prostate cancer (CRPC) remains one of the leading causes of cancer deaths among men. Conventional therapies targeting androgen signaling driven tumor growth have provided limited survival benefit in patients. Recent identification of the critical molecular and cellular events surrounding tumor progression, invasion, and metastasis to the bone as well as other sites provide new insights in targeting advanced disease. Epithelial mesenchymal transition (EMT) is a process via which epithelial cells undergo morphological changes to a motile mesenchymal phenotype, a phenomenon implicated in cancer metastasis but also therapeutic resistance. Therapeutic targeting of EMT has the potential to open a new avenue in the treatment paradigm of CRPC through the reversion of the invasive mesenchymal phenotype to the well differentiated tumor epithelial tumor phenotype. Overcoming therapeutic resistance in metastatic prostate cancer is an unmet need in today's clinical management of advanced disease. This review outlines our current understanding of the contribution of EMT and its reversal to MET in prostate cancer progression and therapeutic resistance, and the impact of selected targeting of mechanisms of resistance via EMT towards a therapeutic benefit in patients with CRPC.

The Hydroalcoholic Extract of Matricaria chamomilla Suppresses Migration and Invasion of Human Breast Cancer MDA-MB-468 and MCF-7 Cell Lines

Background:

Matricaria chamomilla is an aromatic plant with antioxidant, anticancer, and anti-inflammatory properties. However, the inhibitory role of M. chamomilla on migration and invasion of human breast cancer cells remains unclear.

Objective:

This study investigated the methods to evaluate these anticancer mechanisms of M. chamomilla on human breast cancer MCF-7 and MDA-MB-468 cell lines.

Materials and Methods:

The cells were treated with hydroalcoholic extract of M. chamomilla at different concentrations (50–1300 μg/mL) for 24, 48, and 72 h in a culture medium containing 10% fetal bovine serum. This study quantified the 50% growth inhibition concentrations (IC₅₀) by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay; apoptosis and necrosis through Hoechst 33342/propidium iodide staining; cell proliferation and clone formation by clonogenic assay as well as cellular migration, invasion, and attachment. After 24, 48, and 72 h of treatment, the IC₅₀levels were 992 ± 2.3 μg/mL, 893 ± 5.4 μg/mL, and 785 ± 4.8 μg/mL against MDA-MB-468, respectively, and 1288 ± 5.6 μg/mL, 926 ± 2.5 μg/mL, and 921 ± 3.5 μg/mL, against MCF-7, respectively. Furthermore, increasing the extract concentrations induced cellular apoptosis and necrosis and decreased cellular invasion or migration through 8 μm pores, colonization and attachment in a dose-dependent manner.

Results:

It indicated time- and dose-dependent anti-invasive and antimigrative or proliferative and antitoxic effects of hydroalcoholic extract of aerial parts of chamomile on breast cancer cells.

Conclusion:

This study demonstrated an effective plant in preventing or treating breast cancer.

SUMMARY

Antioxidant compounds in Matricaria chamomilla have anticancer effects.

Hydroalcoholic extract of M. chamomilla controls cellular proliferation and apoptosis induction.

Hoechst 33342/propidium iodide staining suggested that the extract induces apoptosis more than necrosis.

Hydroalcoholic extract of M. chamomilla prevents colonization and cellular migration of human breast cancer MDA-MB-468 and MCF-7 cell lines in a time- and dose-dependent manner.

M. chamomilla has low cytotoxic effects on natural cells.

Abbreviations Used: IARC: International Agency for Research on Cancer; WHO: World Health Organization; FBS: Fetal bovine serum; MTT: 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide; DMSO: Dimethyl sulfoxide; PI: Propidium iodide; LN: Live cells with normal nucleus; LA: Live cells with apoptized nucleus; DN: Dead cells with normal nucleus; DA: Dead cells with apoptized nucleus; BSA: Bovine serum albumin; ANOVA: Analysis of variance; IC₅₀: 50% growth inhibition concentration; GSE: Grape seed extract

MiR-150 promotes cellular metastasis in non-small cell lung cancer by targeting FOXO4

Previous studies have shown that dysregulation of microRNA-150 (miR-150) is associated with aberrant proliferation of human non-small cell lung cancer (NSCLC) cells. However, whether miR-150 has a critical role in NSCLC cell metastasis is unknown. Here, we reveal that the critical pro-metastatic role of miR-150 in the regulation of epithelial-mesenchymal-transition (EMT) through down-regulation of FOXO4 in NSCLC. In vitro, miR-150 targets 3'UTR region of FOXO4 mRNA, thereby negatively regulating its expression. Clinically, the expression of miR-150 was frequently up-regulated in metastatic NSCLC cell lines and clinical specimens. Contrarily, FOXO4 was frequently down-regulated in NSCLC cell lines and clinical specimens. Functional studies show that ectopic expression of miR-150 enhanced tumor cell metastasis in vitro and in a mouse xenograft model, and triggered EMT-like changes in NSCLC cells (including E-cadherin repression, N-cadherin and Vimentin induction, and mesenchymal morphology). Correspondingly, FOXO4 knockdown exhibited pro-metastatic and molecular effects resembling the effect of miR-150 over-expression. Moreover, NF-κB/snail/YY1/RKIP circuitry regulated by FOXO4 were likely involved in miR-150-induced EMT event. Simultaneous knockdown of miR-150 and FOXO4 abolished the phenotypic and molecular effects caused by individual knockdown of miR-150. Therefore, our study provides previously unidentified pro-metastatic roles and mechanisms of miR-150 in NSCLC.

Population Heterogeneity in the Epithelial to Mesenchymal Transition Is Controlled by NFAT and Phosphorylated Sp1

Epithelial to mesenchymal transition (EMT) is an essential differentiation program during tissue morphogenesis and remodeling. EMT is induced by soluble transforming growth factor β (TGF-β) family members, and restricted by vascular endothelial growth factor family members. While many downstream molecular regulators of EMT have been identified, these have been largely evaluated individually without considering potential crosstalk. In this study, we created an ensemble of dynamic mathematical models describing TGF-β induced EMT to better understand the operational hierarchy of this complex molecular program. We used ordinary differential equations (ODEs) to describe the transcriptional and post-translational regulatory events driving EMT. Model parameters were estimated from multiple data sets using multiobjective optimization, in combination with cross-validation. TGF-β exposure drove the model population toward a mesenchymal phenotype, while an epithelial phenotype was enhanced following vascular endothelial growth factor A (VEGF-A) exposure. Simulations predicted that the transcription factors phosphorylated SP1 and NFAT were master regulators promoting or inhibiting EMT, respectively. Surprisingly, simulations also predicted that a cellular population could exhibit phenotypic heterogeneity (characterized by a significant fraction of the population with both high epithelial and mesenchymal marker expression) if treated simultaneously with TGF-β and VEGF-A. We tested this prediction experimentally in both MCF10A and DLD1 cells and found that upwards of 45% of the cellular population acquired this hybrid state in the presence of both TGF-β and VEGF-A. We experimentally validated the predicted NFAT/Sp1 signaling axis for each phenotype response. Lastly, we found that cells in the hybrid state had significantly different functional behavior when compared to VEGF-A or TGF-β treatment alone. Together, these results establish a predictive mechanistic model of EMT susceptibility, and potentially reveal a novel signaling axis which regulates carcinoma progression through an EMT versus tubulogenesis response.

Long non-coding RNAs: potential new biomarkers for predicting tumor invasion and metastasis

Long non-coding RNAs (lncRNAs) play important roles in malignant neoplasia. Indeed, many hallmarks of cancer define that the malignant phenotype of tumor cells are controlled by lncRNAs. Despite a growing number of studies highlighting their importance in cancer, there has been no systematic review of metastasis-associated lncRNAs in various cancer types. Accordingly, we focus on the key metastasis-related lncRNAs and outline their expression status in cancer tissues by reviewing the previous stuides, in order to summarize the nowadays research achivements for lncRNAs related to cancer metastasis. Medline, EMBASE, as well as PubMed databases were applied to study lncRNAs which were tightly associated with tumor invasion and metastasis. Up to now, a substantial number of lncRNAs have been found to have important biological functions. In this review, according to their various features in cancer, lncRNAs were roughly divided into three categories: promoting tumor invasion and metastasis, negative regulation of tumor metastasis and with dual regulatory roles. The present studies may establish the foundation for both further research on the mechanisms of cancer progression and future lncRNA-based clinical applications.

The biological role of epithelial-mesenchymal transition in lung cancer (Review)

Epithelial-mesenchymal transition (EMT) is a process whereby epithelial cells gradually transform into mesenchymal-like cells losing their epithelial functionality and characteristics. EMT is thought to be involved in the pathogenesis of numerous lung diseases ranging from developmental disorders and fibrotic tissue remodeling to lung cancer. Lung cancer is the most lethal form of cancer worldwide, and despite significant therapeutic improvements, the patient survival rate still remains low. Activation of EMT endows invasive and metastatic properties upon cancer cells that favor successful colonization of distal target organs. The present review provides a brief insight into the mechanism and biological assessment methods of EMT in lung cancer and summarizes the recent literature highlighting the controversial experimental data and conclusions.

Fractionated irradiation-induced EMT-like phenotype conferred radioresistance in esophageal squamous cell carcinoma

The efficacy of radiotherapy, one major treatment modality for esophageal squamous cell carcinoma (ESCC) is severely attenuated by radioresistance. Epithelial-to-mesenchymal transition (EMT) is a cellular process that determines therapy response and tumor progression. However, whether EMT is induced by ionizing radiation and involved in tumor radioresistance has been less studied in ESCC. Using multiple fractionated irradiation, the radioresistant esophageal squamous cancer cell line KYSE-150R had been established from its parental cell line KYSE-150. We found KYSE-150R displayed a significant EMT phenotype with an elongated spindle shape and down-regulated epithelial marker E-cadherin and up-regulated mesenchymal marker N-cadherin in comparison with KYSE-150. Furthermore, KYSE-150R also possessed some stemness-like properties characterized by density-dependent growth promotion and strong capability for sphere formation and tumorigenesis in NOD-SCID mice. Mechanical studies have revealed that WISP1, a secreted matricellular protein, is highly expressed in KYSE-150R and mediates EMT-associated radioresistance both in ESCC cells and in xenograft tumor models. Moreover, WISP1 has been demonstrated to be closely associated with the EMT phenotype observed in ESCC patients and to be an independent prognosis factor of ESCC patients treated with radiotherapy. Our study highlighted WISP1 as an attractive target to reverse EMT-associated radioresistance in ESCC and can be used as an independent prognostic factor of patients treated with radiotherapy.

Ubiquitin-Conjugating Enzyme E2T is an Independent Prognostic Factor and Promotes Gastric Cancer Progression

Ubiquitin-conjugating enzyme E2T (UBE2T) is a member of the E2 family that mediates the ubiquitin-proteasome system and regulates gene expression. It is a major oncogene in several cancers such as lung cancer and breast cancer, while the potential functions of UBE2T in gastric cancer (GC) remains largely unknown. Here, we identified the roles of UBE2T in GC progression and its potential to act as a prognostic marker of GC. Our data demonstrated that UBE2T was significantly upregulated in gastric cancer tissues, and the high expression of UBE2T was significantly correlated with poor differentiation, high T classification, and poor prognosis. In vitro experiments indicated that UBE2T promoted cell proliferation and inhibited cell cycle arrest. In addition, we observed that UBE2T modulated cell mobility by inducing epithelial-mesenchymal transition. Collectively, these findings suggest that UBE2T plays an important role in the tumorigenesis of gastric cancer and could act as a potential independent prognostic factor for cancer therapy.

Snail heterogeneity in clear cell renal cell carcinoma

Background

Intratumor heterogeneity may be responsible of the unpredictable aggressive clinical behavior that some clear cell renal cell carcinomas display. This clinical uncertainty may be caused by insufficient sampling, leaving out of histological analysis foci of high grade tumor areas. Although molecular approaches are providing important information on renal intratumor heterogeneity, a focus on this topic from the practicing pathologist’ perspective is still pending.

Methods

Four distant tumor areas of 40 organ-confined clear cell renal cell carcinomas were selected for histopathological and immunohistochemical evaluation. Tumor size, cell type (clear/granular), Fuhrman’s grade, Staging, as well as immunostaining with Snail, ZEB1, Twist, Vimentin, E-cadherin, β-catenin, PTEN, p-Akt, p110α, and SETD2, were analyzed for intratumor heterogeneity using a classification and regression tree algorithm.

Results

Cell type and Fuhrman’s grade were heterogeneous in 12.5 and 60 % of the tumors, respectively. If cell type was homogeneous (clear cell) then the tumors were low-grade in 88.57 % of cases. Immunostaining heterogeneity was significant in the series and oscillated between 15 % for p110α and 80 % for Snail. When Snail immunostaining was homogeneous the tumor was histologically homogeneous in 100 % of cases. If Snail was heterogeneous, the tumor was heterogeneous in 75 % of the cases. Average tumor diameter was 4.3 cm. Tumors larger than 3.7 cm were heterogeneous for Vimentin immunostaining in 72.5 % of cases. Tumors displaying negative immunostaining for both ZEB1 and Twist were low grade in 100 % of the cases.

Conclusions

Intratumor heterogeneity is a common event in clear cell renal cell carcinoma, which can be monitored by immunohistochemistry in routine practice. Snail seems to be particularly useful in the identification of intratumor heterogeneity. The suitability of current sampling protocols in renal cancer is discussed.

Tumour progression and metastasis

The two biological mechanisms that determine types of malignancy are infiltration and metastasis, for which tumour microenvironment plays a key role in developing and establishing the morphology, growth and invasiveness of a malignancy. The microenvironment is formed by complex tissue containing the extracellular matrix, tumour and non-tumour cells, a signalling network of cytokines, chemokines, growth factors, and proteases that control autocrine and paracrine communication among individual cells, facilitating tumour progression. During the development of the primary tumour, the tumour stroma and continuous genetic changes within the cells makes it possible for them to migrate, having to count on a pre-metastatic niche receptor that allows the tumour’s survival and distant growth. These niches are induced by factors produced by the primary tumour; if it is eradicated, the active niches become responsible for activating the latent disseminated cells. Due to the importance of these mechanisms, the strategies that develop tumour cells during tumour progression and the way in which the microenvironment influences the formation of metastasis are reviewed. It also suggests that the metastatic niche can be an ideal target for new treatments that make controlling metastasis possible.

Epithelial-Mesenchymal Transition and Breast Cancer

Breast cancer is the most common cancer in women and distant site metastasis is the main cause of death in breast cancer patients. There is increasing evidence supporting the role of epithelial-mesenchymal transition (EMT) in tumor cell progression, invasion, and metastasis. During the process of EMT, epithelial cancer cells acquire molecular alternations that facilitate the loss of epithelial features and gain of mesenchymal phenotype. Such transformation promotes cancer cell migration and invasion. Moreover, emerging evidence suggests that EMT is associated with the increased enrichment of cancer stem-like cells (CSCs) and these CSCs display mesenchymal characteristics that are resistant to chemotherapy and target therapy. However, the clinical relevance of EMT in human cancer is still under debate. This review will provide an overview of current evidence of EMT from studies using clinical human breast cancer tissues and its associated challenges.

microRNA miR-200b affects proliferation, invasiveness and stemness of endometriotic cells by targeting ZEB1, ZEB2 and KLF4

Endometriosis is characterized by growth of endometrial tissue at ectopic locations. Down-regulation of microRNA miR-200b is observed in endometriosis and malignant disease, driving tumour cells towards an invasive state by enhancing epithelial-to-mesenchymal transition (EMT). miR-200b up-regulation may inhibit EMT and invasive growth in endometriosis. To study its functional impact on the immortalized endometriotic cell line 12Z, the stromal cell line ST-T1b, and primary endometriotic stroma cells, a transient transfection approach with microRNA precursors was employed. Expression of bioinformatically predicted targets of miR-200b was analysed by qPCR. The cellular phenotype was monitored by Matrigel invasion assays, digital-holographic video microscopy and flow cytometry. qPCR revealed significant down-regulation of ZEB1 (P < 0.05) and ZEB2 (P < 0.01) and an increase in E-cadherin (P < 0.01). miR-200b overexpression decreased invasiveness (P < 0.0001) and cell motility (P < 0.05). In contrast, cell proliferation (P < 0.0001) and the stemness-associated side population phenotype (P < 0.01) were enhanced following miR-200b transfection. These properties were possibly due to up-regulation of the pluripotency-associated transcription factor KLF4 (P < 0.05) and require attention when considering therapeutic strategies. In conclusion, up-regulation of miR-200b reverts EMT, emerging as a potential therapeutic approach to inhibit endometriotic cell motility and invasiveness.

Epithelial-mesenchymal transition in glioblastoma progression

Epithelial-mesenchymal transition (EMT) is a reversible biological process that occurs in epithelial cells. EMT ultimately leads to the acquisition of a mesenchymal phenotype, characterized by increased cell motility and resistance to genotoxic agents. These processes mostly overlap with the acquirement of stem cell properties in differentiated tumor cells. With regard to gliomas, the clinical picture is heterogeneous, even within the same grades and histological categories of the disease. Furthermore, the areas of invasion and responses to radiochemotherapy are markedly different among cases, and occasionally even in the same patient. Such phenotypic diversity in glioma tissues may be caused by various microenvironmental factors, as well as intrinsic genetic alterations. The current review focuses on the EMT-inducing factors that are present in gliomas; these typically vary from those observed in epithelial cancers, as no basement membrane is present. Furthermore, the most important cell-cell contact factor, E-cadherin, is rarely expressed in gliomas. The microenvironment that induces EMT in gliomas is characterized by hypoxia and the enrichment of myeloid cells following stimulation by transforming growth factor-β. Anti-vascular endothelial growth factor therapy, including the use of bevacizumab, may be a suitable candidate to modulate the glioma microenvironment.

Translating epithelial mesenchymal transition markers into the clinic: Novel insights from proteomics

The growing understanding of the molecular mechanisms underlying epithelial-to-mesenchymal transition (EMT) may represent a potential source of clinical markers. Despite EMT drivers have not yet emerged as candidate markers in the clinical setting, their association with established clinical markers may improve their specificity and sensitivity. Mass spectrometry-based platforms allow analyzing multiple samples for the expression of EMT candidate markers, and may help to diagnose diseases or monitor treatment efficiently. This review highlights proteomic approaches applied to elucidate the differences between epithelial and mesenchymal tumors and describes how these can be used for target discovery and validation.

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.