Epithelial-mesenchymal transition (EMT) encompasses dynamic changes in cellular organization from epithelial to mesenchymal phenotypes, which leads to functional changes in cell migration and ...invasion. EMT occurs in a diverse range of physiological and pathological conditions and is driven by a conserved set of inducing signals, transcriptional regulators and downstream effectors. With over 5,700 publications indexed by Web of Science in 2019 alone, research on EMT is expanding rapidly. This growing interest warrants the need for a consensus among researchers when referring to and undertaking research on EMT. This Consensus Statement, mediated by 'the EMT International Association' (TEMTIA), is the outcome of a 2-year-long discussion among EMT researchers and aims to both clarify the nomenclature and provide definitions and guidelines for EMT research in future publications. We trust that these guidelines will help to reduce misunderstanding and misinterpretation of research data generated in various experimental models and to promote cross-disciplinary collaboration to identify and address key open questions in this research field. While recognizing the importance of maintaining diversity in experimental approaches and conceptual frameworks, we emphasize that lasting contributions of EMT research to increasing our understanding of developmental processes and combatting cancer and other diseases depend on the adoption of a unified terminology to describe EMT.
Abstract
Drugs targeting a single TK/RTK in the treatment of solid cancers has not had the same success seen in blood cancers. This is, in part, due to acquired resistance in solid cancers arising ...from a range of mechanisms including the upregulation of compensatory RTK signalling. Rather than attempting to inhibit individual compensatory RTK—requiring knowledge of which RTKs are upregulated in any given tumour—strategies to universally inhibit signalling from multiple RTKs may represent an effective alternative. Endosomal trafficking of RTKs is a common conduit that can regulate signalling from multiple RTKs simultaneously. As such, we posit that targeting endosomal trafficking—in particular, aberrant post‐translational modifications in cancers that contribute to dysregulated endosomal trafficking—could inhibit oncogenic signalling driven by multiple RTKs and pave the way for the development of a novel class of inhibitors that shift the trafficking of RTKs to inhibit tumour growth.
Members of the miR‐200 family are critical gatekeepers of the epithelial state, restraining expression of pro‐mesenchymal genes that drive epithelial–mesenchymal transition (EMT) and contribute to ...metastatic cancer progression. Here, we show that miR‐200c and another epithelial‐enriched miRNA, miR‐375, exert widespread control of alternative splicing in cancer cells by suppressing the RNA‐binding protein Quaking (QKI). During EMT, QKI‐5 directly binds to and regulates hundreds of alternative splicing targets and exerts pleiotropic effects, such as increasing cell migration and invasion and restraining tumour growth, without appreciably affecting mRNA levels. QKI‐5 is both necessary and sufficient to direct EMT‐associated alternative splicing changes, and this splicing signature is broadly conserved across many epithelial‐derived cancer types. Importantly, several actin cytoskeleton‐associated genes are directly targeted by both QKI and miR‐200c, revealing coordinated control of alternative splicing and mRNA abundance during EMT. These findings demonstrate the existence of a miR‐200/miR‐375/QKI axis that impacts cancer‐associated epithelial cell plasticity through widespread control of alternative splicing.
Synopsis
miR‐200 and miR‐375 regulate the level of the RNA‐binding protein, Quaking (QKI), which orchestrates widespread control of alternative splicing during epithelial‐mesenchymal transition (EMT), thereby affecting multiple facets of cancer‐associated epithelial cell plasticity.
miR‐200c and miR‐375 control EMT‐associated alternative splicing by suppressing QKI.
QKI‐5 influences cell plasticity, invasion and tumour growth by modulating alternative splicing.
Actin cytoskeleton‐associated genes are targeted both by QKI and miR‐200c, revealing coordinated control of alternative splicing and mRNA abundance during EMT.
While miRNAs of the miR‐200 family are known to promote EMT and cancer progression via target mRNA repression, they exert a separate effect on epithelial cell plasticity by modulating alternative splicing signatures.
The microRNAs of the miR‐200 family maintain the central characteristics of epithelia and inhibit tumor cell motility and invasiveness. Using the Ago‐HITS‐CLIP technology for transcriptome‐wide ...identification of direct microRNA targets in living cells, along with extensive validation to verify the reliability of the approach, we have identified hundreds of miR‐200a and miR‐200b targets, providing insights into general features of miRNA target site selection. Gene ontology analysis revealed a predominant effect of miR‐200 targets in widespread coordinate control of actin cytoskeleton dynamics. Functional characterization of the miR‐200 targets indicates that they constitute subnetworks that underlie the ability of cancer cells to migrate and invade, including coordinate effects on Rho‐ROCK signaling, invadopodia formation, MMP activity, and focal adhesions. Thus, the miR‐200 family maintains the central characteristics of the epithelial phenotype by acting on numerous targets at multiple levels, encompassing both cytoskeletal effectors that control actin filament organization and dynamics, and upstream signals that locally regulate the cytoskeleton to maintain cell morphology and prevent cell migration.
Synopsis
miR‐200 microRNAs are involved in the maintenance of epithelial integrity. Direct, transcriptome‐wide target detection and validation identifies genes functionally grouped as regulators of Rho GTPase signaling, invadopodia formation, metalloprotease activity and cell adhesion, which together regulate cell motility, migration and cancer metastasis.
The global profile of miR‐200 targets in breast cancer cells reveals a network of cytoskeletal regulators
miR‐200 is found to control invadopodia, focal adhesions and Rho GTPase signaling.
Canonical seed‐3′UTR target site interactions are dominant, but target sites in coding regions and non‐canonical interactions are also detected.
Target genes identified in cell lines negatively correlate with miR‐200 across human breast cancer samples as well.
miR‐200 microRNAs are involved in the maintenance of epithelial integrity. Direct, transcriptome‐wide target detection and validation identifies genes functionally grouped as regulators of Rho GTPase signaling, invadopodia formation, metalloprotease activity and cell adhesion, which together regulate cell motility, migration and cancer metastasis.
Kidney disease progression can be affected by Na
abundance. A key regulator of Na
homeostasis is the ubiquitin ligase NEDD4-2 and its deficiency leads to increased Na
transport activity and ...salt-sensitive progressive kidney damage. However, the mechanisms responsible for high Na
induced damage remain poorly understood. Here we show that a high Na
diet compromised kidney function in Nedd4-2-deficient mice, indicative of progression toward end-stage renal disease. Injury was characterized by enhanced tubule dilation and extracellular matrix accumulation, together with sustained activation of both Wnt/β-catenin and TGF-β signaling. Nedd4-2 knockout in cortical collecting duct cells also activated these pathways and led to epithelial-mesenchymal transition. Furthermore, low dietary Na
rescued kidney disease in Nedd4-2-deficient mice and silenced Wnt/β-catenin and TGF-β signaling. Our study reveals the important role of NEDD4-2-dependent ubiquitination in Na
homeostasis and protecting against aberrant Wnt/β-catenin/TGF-β signaling in progressive kidney disease.
Epithelial to mesenchymal transition (EMT) facilitates tissue remodelling during embryonic development and is viewed as an essential early step in tumour metastasis. We found that all five members of ...the microRNA-200 family (miR-200a, miR-200b, miR-200c, miR-141 and miR-429) and miR-205 were markedly downregulated in cells that had undergone EMT in response to transforming growth factor (TGF)-β or to ectopic expression of the protein tyrosine phosphatase Pez. Enforced expression of the miR-200 family alone was sufficient to prevent TGF-β-induced EMT. Together, these microRNAs cooperatively regulate expression of the E-cadherin transcriptional repressors ZEB1 (also known as δEF1) and SIP1 (also known as ZEB2), factors previously implicated in EMT and tumour metastasis. Inhibition of the microRNAs was sufficient to induce EMT in a process requiring upregulation of ZEB1 and/or SIP1. Conversely, ectopic expression of these microRNAs in mesenchymal cells initiated mesenchymal to epithelial transition (MET). Consistent with their role in regulating EMT, expression of these microRNAs was found to be lost in invasive breast cancer cell lines with mesenchymal phenotype. Expression of the miR-200 family was also lost in regions of metaplastic breast cancer specimens lacking E-cadherin. These data suggest that downregulation of the microRNAs may be an important step in tumour progression.
microRNAs (miRNA) are well suited to the task of regulating gene expression networks, because any given miRNA has the capacity to target dozens, if not hundreds, of genes. The simultaneous targeting ...of multiple genes within a pathway may enable miRNAs to more strongly regulate the pathway, or to achieve more subtle control through the targeting of distinct subnetworks of genes. Therefore, as our capacity to discover miRNA targets en masse increases, so must our consideration of the complex networks in which these genes participate. We highlight recent studies in which the comprehensive identification of targets has been used to elucidate miRNA-regulated gene networks in cancer, focusing especially upon miRNAs such as members of the miR-200 family that regulate epithelial-mesenchymal transition (EMT), a reversible phenotypic switch whereby epithelial cells take on the more invasive properties of their mesenchymal counterparts. These studies have expanded our understanding of the roles of miRNAs in EMT, which were already known to form important regulatory loops with key transcription factors to regulate the epithelial or mesenchymal properties of cells.
Abstract Cancer progression is a complex series of events thought to incorporate the reversible developmental process of epithelial-to-mesenchymal transition (EMT). In vitro , the microRNA-200 family ...maintains the epithelial phenotype by posttranscriptionally inhibiting the E-cadherin repressors, ZEB1 and ZEB2 . Here, we used in situ hybridization and immunohistochemistry to assess expression of miR-200 and EMT biomarkers in formalin-fixed paraffin-embedded human colorectal adenocarcinomas. In addition, laser capture microdissection and quantitative real-time polymerase chain reaction were employed to quantify levels of miR-200 in the normal epithelium, tumor core, invasive front, and stroma. We find that miR-200 is downregulated at the invasive front of colorectal adenocarcinomas that have destroyed and invaded beyond the basement membrane. However, regional lymph node metastases and vascular carcinoma deposits show strong expression of miR-200, suggesting this family of miRNAs is involved in the recapitulation of the primary tumor phenotype at metastatic sites. In contrast, adenomas and adenocarcinomas with intact basement membranes showed uniform miR-200 expression from the tumor core to the tumor-host interface. Taken together, these data support the involvement of EMT and mesenchymal-to-epithelial transition (MET) in the metastasis cascade and show that miR-200 is downregulated in the initial stages of stromal invasion but is restored at metastatic sites.
Stathmin mediates cell migration and invasion in vitro, and metastasis in vivo. To investigate stathmin's role on the metastatic process, we performed integrated mRNA-miRNA expression analysis to ...identify pathways regulated by stathmin.
MiRNA and gene arrays followed by miRNA-target-gene integration were performed on stathmin-depleted neuroblastoma cells (Ctrl
vs. Stmn Seq2
). The expression of the predicted target PTPN14 was evaluated by RT-qPCR, western blot and immunohistochemistry. Gene-silencing technology was used to assess the role of PTPN14 on proliferation, migration, invasion and signalling pathway.
Stathmin levels modulated the expression of genes and miRNA in neuroblastoma cells, leading to a deregulation of migration and invasion pathways. Consistent with gene array data, PTPN14 mRNA and protein expression were downregulated in stathmin- depleted neuroblastoma cells and xenografts. In two independent neuroblastoma cells, suppression of PTPN14 expression led to an increase in cell migration and invasion. PTPN14 and stathmin expression did not act in a feedback regulatory loop in PTPN14- depleted cells, suggesting a complex interplay of signalling pathways. The effect of PTPN14 on YAP pathway activation was cell-type dependent.
Our findings demonstrate that stathmin levels can regulate PTPN14 expression, which can modulate neuroblastoma cell migration and invasion.
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