miR-34 and SNAIL form a double-negative feedback loop to regulate epithelial-mesenchymal transitions

The microRNA Let-7 and its exosomal form: Epigenetic regulators of gynecological cancers

Many types of gynecological cancer (GC) are often silent until they reach an advanced stage, and are therefore often diagnosed too late for effective treatment. Hence, there is a real need for more efficient diagnosis and treatment for patients with GC. During recent years, researchers have increasingly studied the impact of microRNAs cancer development, leading to a number of applications in detection and treatment. MicroRNAs are a particular group of tiny RNA molecules that regulate regular gene expression by affecting the translation process. The downregulation of numerous miRNAs has been observed in human malignancies. Let-7 is an example of a miRNA that controls cellular processes as well as signaling cascades to affect post-transcriptional gene expression. Recent research supports the hypothesis that enhancing let-7 expression in those cancers where it is downregulated may be a potential treatment option. Exosomes are tiny vesicles that move through body fluids and can include components like miRNAs (including let-7) that are important for communication between cells. Studies proved that exosomes are able to enhance tumor growth, angiogenesis, chemoresistance, metastasis, and immune evasion, thus suggesting their importance in GC management.

Epithelial-mesenchymal transition in tissue repair and degeneration

Epithelial-mesenchymal transitions (EMTs) are the epitome of cell plasticity in embryonic development and cancer; during EMT, epithelial cells undergo dramatic phenotypic changes and become able to migrate to form different tissues or give rise to metastases, respectively. The importance of EMTs in other contexts, such as tissue repair and fibrosis in the adult, has become increasingly recognized and studied. In this Review, we discuss the function of EMT in the adult after tissue damage and compare features of embryonic and adult EMT. Whereas sustained EMT leads to adult tissue degeneration, fibrosis and organ failure, its transient activation, which confers phenotypic and functional plasticity on somatic cells, promotes tissue repair after damage. Understanding the mechanisms and temporal regulation of different EMTs provides insight into how some tissues heal and has the potential to open new therapeutic avenues to promote repair or regeneration of tissue damage that is currently irreversible. We also discuss therapeutic strategies that modulate EMT that hold clinical promise in ameliorating fibrosis, and how precise EMT activation could be harnessed to enhance tissue repair.

LINC01021 Attenuates Expression and Affects Alternative Splicing of a Subset of p53-Regulated Genes

BACKGROUND

Loss of the p53-inducible LINC01021 in p53-proficient CRC cell lines results in increased sensitivity to DNA-damaging chemotherapeutics. Here, we comprehensively analyze how LINC01021 affects the p53-induced transcriptional program.

METHODS

Using a CRISPR/Cas9-approach, we deleted the p53 binding site in the LINC01021 promoter of SW480 colorectal cancer cells and subjected them to RNA-Seq analysis after the activation of ectopic p53. RNA affinity purification followed by mass spectrometry was used to identify proteins associated with LINC01021.

RESULTS

Loss of the p53-inducibility of LINC01021 resulted in an ~1.8-fold increase in the number of significantly regulated mRNAs compared to LINC01021 wild-type cells after ectopic activation of p53. A subset of direct p53 target genes, such as NOXA and FAS, displayed significantly stronger induction when the p53-inducibility of LINC01021 was abrogated. Loss of the p53-inducibility of LINC01021 resulted in alternative splicing of a small number of mRNAs, such as ARHGAP12, HSF2, and LYN. Several RNA binding proteins involved in pre-mRNA splicing were identified as interaction partners of LINC01021 by mass spectrometry.

CONCLUSIONS

Our results suggest that LINC01021 may restrict the extent and strength of p53-mediated transcriptional changes via context-dependent regulation of the expression and splicing of a subset of p53-regulated genes.

Pooled CRISPR Screening Identifies P-Bodies as Repressors of Cancer Epithelial-Mesenchymal Transition

Epithelial-mesenchymal transition (EMT) is a fundamental cellular process frequently hijacked by cancer cells to promote tumor progression, especially metastasis. EMT is orchestrated by a complex molecular network acting at different layers of gene regulation. In addition to transcriptional regulation, posttranscriptional mechanisms may also play a role in EMT. Here, we performed a pooled CRISPR screen analyzing the influence of 1,547 RNA-binding proteins on cell motility in colon cancer cells and identified multiple core components of P-bodies (PB) as negative modulators of cancer cell migration. Further experiments demonstrated that PB depletion by silencing DDX6 or EDC4 could activate hallmarks of EMT thereby enhancing cell migration in vitro as well as metastasis formation in vivo. Integrative multiomics analysis revealed that PBs could repress the translation of the EMT driver gene HMGA2, which contributed to PB-meditated regulation of EMT. This mechanism is conserved in other cancer types. Furthermore, endoplasmic reticulum stress was an intrinsic signal that induced PB disassembly and translational derepression of HMGA2. Taken together, this study has identified a function of PBs in the regulation of EMT in cancer.

SIGNIFICANCE

Systematic investigation of the influence of posttranscriptional regulation on cancer cell motility established a connection between P-body-mediated translational control and EMT, which could be therapeutically exploited to attenuate metastasis formation.

Melatonin and Its Role in the Epithelial-to-Mesenchymal Transition (EMT) in Cancer

The epithelial-to-mesenchymal transition (EMT) is a cell-biological program that occurs during the progression of several physiological processes and that can also take place during pathological situations such as carcinogenesis. The EMT program consists of the sequential activation of a number of intracellular signaling pathways aimed at driving epithelial cells toward the acquisition of a series of intermediate phenotypic states arrayed along the epithelial-mesenchymal axis. These phenotypic features include changes in the motility, conformation, polarity and functionality of cancer cells, ultimately leading cells to stemness, increased invasiveness, chemo- and radioresistance and the formation of cancer metastasis. Amongst the different existing types of the EMT, type 3 is directly involved in carcinogenesis. A type 3 EMT occurs in neoplastic cells that have previously acquired genetic and epigenetic alterations, specifically affecting genes involved in promoting clonal outgrowth and invasion. Markers such as E-cadherin; N-cadherin; vimentin; and transcription factors (TFs) like Twist, Snail and ZEB are considered key molecules in the transition. The EMT process is also regulated by microRNA expression. Many miRNAs have been reported to repress EMT-TFs. Thus, Snail 1 is repressed by miR-29, miR-30a and miR-34a; miR-200b downregulates Slug; and ZEB1 and ZEB2 are repressed by miR-200 and miR-205, respectively. Occasionally, some microRNA target genes act downstream of the EMT master TFs; thus, Twist1 upregulates the levels of miR-10b. Melatonin is an endogenously produced hormone released mainly by the pineal gland. It is widely accepted that melatonin exerts oncostatic actions in a large variety of tumors, inhibiting the initiation, progression and invasion phases of tumorigenesis. The molecular mechanisms underlying these inhibitory actions are complex and involve a great number of processes. In this review, we will focus our attention on the ability of melatonin to regulate some key EMT-related markers, transcription factors and micro-RNAs, summarizing the multiple ways by which this hormone can regulate the EMT. Since melatonin has no known toxic side effects and is also known to help overcome drug resistance, it is a good candidate to be considered as an adjuvant drug to conventional cancer therapies.

Impact of Long-Lasting Environmental Factors on Regulation Mediated by the miR-34 Family

The present review focuses on the interactions of newly emerging environmental factors with miRNA-mediated regulation. In particular, we draw attention to the effects of phthalates, electromagnetic fields (EMFs) and a disrupted light/dark cycle. miRNAs are small non-coding RNA molecules with a tremendous regulatory impact, which is usually executed via gene expression inhibition. To address the capacity of environmental factors to influence miRNA-mediated regulation, the miR-34 family was selected for its well-described oncostatic and neuro-modulatory properties. The expression of miR-34 is in a tissue-dependent manner to some extent under the control of the circadian system. There is experimental evidence implicating that phthalates, EMFs and the circadian system interact with the miR-34 family, in both lines of its physiological functioning. The inhibition of miR-34 expression in response to phthalates, EMFs and light contamination has been described in cancer tissue and cell lines and was associated with a decline in oncostatic miR-34a signalling (decrease in p21 expression) and a promotion of tumorigenesis (increases in Noth1, cyclin D1 and cry1 expressions). The effects of miR-34 on neural functions have also been influenced by phthalates, EMFs and a disrupted light/dark cycle. Environmental factors shifted the effects of miR-34 from beneficial to the promotion of neurodegeneration and decreased cognition. Moreover, the apoptogenic capacity of miR-34 induced via phthalate administration in the testes has been shown to negatively influence germ cell proliferation. To conclude, as the oncostatic and positive neuromodulatory functions of the miR-34 family can be strongly influenced by environmental factors, their interactions should be taken into consideration in translational medicine.

MicroRNA signatures differentiate types, grades, and stages of breast invasive ductal carcinoma (IDC): miRNA-target interacting signaling pathways

BACKGROUND

Invasive ductal carcinoma (IDC) is the most common form of breast cancer which accounts for 85% of all breast cancer diagnoses. Non-invasive and early stages have a better prognosis than late-stage invasive cancer that has spread to lymph nodes. The involvement of microRNAs (miRNAs) in the initiation and progression of breast cancer holds great promise for the development of molecular tools for early diagnosis and prognosis. Therefore, developing a cost effective, quick and robust early detection protocol using miRNAs for breast cancer diagnosis is an imminent need that could strengthen the health care system to tackle this disease around the world.

METHODS

We have analyzed putative miRNAs signatures in 100 breast cancer samples using two independent high fidelity array systems. Unique and common miRNA signatures from both array systems were validated using stringent double-blind individual TaqMan assays and their expression pattern was confirmed with tissue microarrays and northern analysis. In silico analysis were carried out to find miRNA targets and were validated with q-PCR and immunoblotting. In addition, functional validation using antibody arrays was also carried out to confirm the oncotargets and their networking in different pathways. Similar profiling was carried out in Brca2/p53 double knock out mice models using rodent miRNA microarrays that revealed common signatures with human arrays which could be used for future in vivo functional validation.

RESULTS

Expression profile revealed 85% downregulated and 15% upregulated microRNAs in the patient samples of IDC. Among them, 439 miRNAs were associated with breast cancer, out of which 107 miRNAs qualified to be potential biomarkers for the stratification of different types, grades and stages of IDC after stringent validation. Functional validation of their putative targets revealed extensive miRNA network in different oncogenic pathways thus contributing to epithelial-mesenchymal transition (EMT) and cellular plasticity.

CONCLUSION

This study revealed potential biomarkers for the robust classification as well as rapid, cost effective and early detection of IDC of breast cancer. It not only confirmed the role of these miRNAs in cancer development but also revealed the oncogenic pathways involved in different progressive grades and stages thus suggesting a role in EMT and cellular plasticity during breast tumorigenesis per se and IDC in particular. Thus, our findings have provided newer insights into the miRNA signatures for the classification and early detection of IDC.

Identifying critical regulatory interactions in cell fate decision and transition by systematic perturbation analysis

One of the most significant challenges in biology is to elucidate the roles of various regulatory interactions in cell fate decision and transition. However, it remains to be fully clarified how they cooperate and determine fate transition. Here, a general framework based on statistical analysis and bifurcation theory is proposed to identify crucial regulatory interactions and how they play decisive roles in fate transition. More exactly, specific feedback loops determine occurrence of bifurcations by which cell fate transition can be realized. While regulatory interactions in the feedback loops determine the direction of transition. In addition, two-parameter bifurcation analysis further provides detailed understanding of how the fate transition based on statistical analysis occurs. Statistical analysis can also be used to reveal synergistic combinatorial perturbations by which fate transition can be more efficiently realized. The integrative analysis approach can be used to identify critical regulatory interactions in cell fate transition and reveal how specific cell fate transition occurs. To verify feasibility of the approach, the epithelial to mesenchymal transition (EMT) network is chosen as an illustrative example. In agreement with experimental observations, the approach reveals some critical regulatory interactions and underlying mechanisms in cell fate determination and transitions between three states. The approach can also be applied to analyze other regulatory networks related to cell fate decision and transition.

Cellular Transdifferentiation: A Crucial Mechanism of Fibrosis in Systemic Sclerosis

Systemic Sclerosis (SSc) is a systemic autoimmune disease of unknown etiology with a highly complex pathogenesis that despite extensive investigation is not completely understood. The clinical and pathologic manifestations of the disease result from three distinct processes: 1) Severe and frequently progressive tissue fibrosis causing exaggerated and deleterious accumulation of interstitial collagens and other extracellular matrix molecules in the skin and various internal organs; 2) extensive fibroproliferative vascular lesions affecting small arteries and arterioles causing tissue ischemic alterations; and 3) cellular and humoral immunity abnormalities with the production of numerous autoantibodies, some with very high specificity for SSc. The fibrotic process in SSc is one of the main causes of disability and high mortality of the disease. Owing to its essentially universal presence and the severity of its clinical effects, the mechanisms involved in the development and progression of tissue fibrosis have been extensively investigated, however, despite intensive investigation, the precise molecular mechanisms have not been fully elucidated. Several recent studies have suggested that cellular transdifferentiation resulting in the phenotypic conversion of various cell types into activated myofibroblasts may be one important mechanism. Here, we review the potential role that cellular transdifferentiation may play in the development of severe and often progressive tissue fibrosis in SSc.

Docetaxel Inhibits Epithelial-Mesenchymal Transition in Human Mammary Cells

Epithelial-mesenchymal transition (EMT) is a reversible and dynamic biological process in which epithelial cells acquire mesenchymal characteristics including enhanced stemness and migratory ability. EMT can facilitate cancer metastasis and is a known driver of cellular resistance to common chemotherapeutic drugs, such as docetaxel. Current chemotherapeutic practices such as docetaxel treatment can promote EMT and increase the chance of tumor recurrence and resistance, calling for new approaches in cancer treatment. Here we show that prolonged docetaxel treatment at a sub-IC50 concentration inhibits EMT in immortalized human mammary epithelial (HMLE) cells. Using immunofluorescence, flow cytometry, and bulk transcriptomic sequencing to assess EMT progression, we analyzed a range of cellular markers of EMT in docetaxel-treated cells and observed an upregulation of epithelial markers and downregulation of mesenchymal markers in the presence of docetaxel. This finding suggests that docetaxel may have clinical applications not only as a cytotoxic drug but also as an inhibitor of EMT-driven metastasis and multidrug resistance depending on the concentration of its use.

Mutual regulation of TGFβ-induced oncogenic EMT, cell cycle progression and the DDR

TGFβ signaling and the DNA damage response (DDR) are two cellular toolboxes with a strong impact on cancer biology. While TGFβ as a pleiotropic cytokine affects essentially all hallmarks of cancer, the multifunctional DDR mostly orchestrates cell cycle progression, DNA repair, chromatin remodeling and cell death. One oncogenic effect of TGFβ is the partial activation of epithelial-to-mesenchymal transition (EMT), conferring invasiveness, cellular plasticity and resistance to various noxae. Several reports show that both individual networks as well as their interface affect chemo-/radiotherapies. However, the underlying mechanisms remain poorly resolved. EMT often correlates with TGFβ-induced slowing of proliferation, yet numerous studies demonstrate that particularly the co-activated EMT transcription factors counteract anti-proliferative signaling in a partially non-redundant manner. Collectively, evidence piled up over decades underscore a multifaceted, reciprocal inter-connection of TGFβ signaling / EMT with the DDR / cell cycle progression, which we will discuss here. Altogether, we conclude that full cell cycle arrest is barely compatible with the propagation of oncogenic EMT traits and further propose that 'EMT-linked DDR plasticity' is a crucial, yet intricate facet of malignancy, decisively affecting metastasis formation and therapy resistance.

Nidogen-1/NID1 Function and Regulation during Progression and Metastasis of Colorectal Cancer

We have previously shown that the extracellular matrix and basement membrane protein Nidogen1 (NID1) is secreted by more malignant, mesenchymal-like CRC cells and induces the epithelial-mesenchymal transition (EMT) and promotes the migration and invasion of less malignant, epithelial-like CRC cells. Here, we performed a comprehensive bioinformatics analysis of multiple datasets derived from CRC patients and showed that elevated expression of NID1 and the genes ITGA3, ITGB1, and ITGAV, which encode NID1 receptors, is associated with poor prognosis and advanced tumor stage. Accordingly, the expression of NID1, ITGA3, ITGB1, and ITGAV was associated with an EMT signature, which included SNAIL/SNAI1, an EMT-inducing transcription factor. In CRC cells, ectopic SNAIL expression induced NID1 and SNAIL occupancy was detected at an E-box upstream of the NID1 transcription start site. Therefore, NID1 represents a direct target of SNAIL. Ectopic expression of NID1 or treatment with NID1-containing medium endowed non-metastatic CRC cells with the capacity to form lung metastases after xenotransplantation into mice. Suppression of the NID1 receptor ITGAV decreased cell viability, particularly in CMS/consensus molecular subtype 4 CRC cells. Taken together, our results show that NID1 is a direct target of EMT-TF SNAIL and is associated with and promotes CRC progression and metastasis. Furthermore, the NID1 receptor ITGAV represents a candidate therapeutic target in CMS4 colorectal tumors.

Dynamical hallmarks of cancer: Phenotypic switching in melanoma and epithelial-mesenchymal plasticity

Phenotypic plasticity was recently incorporated as a hallmark of cancer. This plasticity can manifest along many interconnected axes, such as stemness and differentiation, drug-sensitive and drug-resistant states, and between epithelial and mesenchymal cell-states. Despite growing acceptance for phenotypic plasticity as a hallmark of cancer, the dynamics of this process remains poorly understood. In particular, the knowledge necessary for a predictive understanding of how individual cancer cells and populations of cells dynamically switch their phenotypes in response to the intensity and/or duration of their current and past environmental stimuli remains far from complete. Here, we present recent investigations of phenotypic plasticity from a systems-level perspective using two exemplars: epithelial-mesenchymal plasticity in carcinomas and phenotypic switching in melanoma. We highlight how an integrated computational-experimental approach has helped unravel insights into specific dynamical hallmarks of phenotypic plasticity in different cancers to address the following questions: a) how many distinct cell-states or phenotypes exist?; b) how reversible are transitions among these cell-states, and what factors control the extent of reversibility?; and c) how might cell-cell communication be able to alter rates of cell-state switching and enable diverse patterns of phenotypic heterogeneity? Understanding these dynamic features of phenotypic plasticity may be a key component in shifting the paradigm of cancer treatment from reactionary to a more predictive, proactive approach.

Salicylate induces AMPK and inhibits c-MYC to activate a NRF2/ARE/miR-34a/b/c cascade resulting in suppression of colorectal cancer metastasis

Aspirin and its active metabolite salicylate have emerged as promising agents for the chemoprevention of colorectal cancer (CRC). Moreover, aspirin suppresses the progression of established CRCs. However, the underlying molecular mechanisms are not completely understood. Here we found that salicylate induces the expression of the miR-34a and miR-34b/c genes, which encode tumor suppressive microRNAs, in a p53-independent manner. Salicylate activated AMPK, thereby activating NRF2, which directly induced miR-34a/b/c expression via ARE motifs. In addition, salicylate suppressed c-MYC, a known repressor of NRF2-mediated transactivation, via activating AMPK. The suppression of c-MYC by salicylate was necessary for NRF2-mediated activation of miR-34a/b/c. Inactivation of miR-34a/b/c largely abrogated the inhibitory effects of salicylate on migration, invasion and metastasis formation by CRC cells. In the future, aspirin and its derivates may be used therapeutically to activate miR-34a and miR-34b/c in tumors that have lost p53.

A logical model of Ewing sarcoma cell epithelial-to-mesenchymal transition supports the existence of hybrid cellular phenotypes

Ewing sarcoma (ES) is a highly aggressive pediatric tumor driven by the RNA-binding protein EWS (EWS)/friend leukemia integration 1 transcription factor (FLI1) chimeric transcription factor, which is involved in epithelial-mesenchymal transition (EMT). EMT stabilizes a hybrid cell state, boosting metastatic potential and drug resistance. Nevertheless, the mechanisms underlying the maintenance of this hybrid phenotype in ES remain elusive. Our study proposes a logical EMT model for ES, highlighting zinc finger E-box-binding homeobox 2 (ZEB2), miR-145, and miR-200 circuits that maintain hybrid states. The model aligns with experimental findings and reveals a previously unknown circuit supporting the mesenchymal phenotype. These insights emphasize the role of ZEB2 in the maintenance of the hybrid state in ES.

The epithelial-mesenchymal plasticity landscape: principles of design and mechanisms of regulation

Epithelial-mesenchymal plasticity (EMP) enables cells to interconvert between several states across the epithelial-mesenchymal landscape, thereby acquiring hybrid epithelial/mesenchymal phenotypic features. This plasticity is crucial for embryonic development and wound healing, but also underlies the acquisition of several malignant traits during cancer progression. Recent research using systems biology and single-cell profiling methods has provided novel insights into the main forces that shape EMP, which include the microenvironment, lineage specification and cell identity, and the genome. Additionally, key roles have emerged for hysteresis (cell memory) and cellular noise, which can drive stochastic transitions between cell states. Here, we review these forces and the distinct but interwoven layers of regulatory control that stabilize EMP states or facilitate epithelial-mesenchymal transitions (EMTs) and discuss the therapeutic potential of manipulating the EMP landscape.

CRISPR/Cas9-mediated inactivation of miR-34a and miR-34b/c in HCT116 colorectal cancer cells: comprehensive characterization after exposure to 5-FU reveals EMT and autophagy as key processes regulated by miR-34

The miR-34a and miR-34b/c encoding genes represent direct targets of the p53 transcription factor, and presumably mediate part of the tumor suppressive effects of p53. Here, we sought to determine their functional relevance by inactivating miR-34a and/or miR-34b/c using a CRISPR/Cas9 approach in the colorectal cancer (CRC) cell line HCT116. Concomitant deletion of miR-34a and miR-34b/c resulted in significantly reduced suppression of proliferation after p53 activation, enhanced migration, invasion and EMT, as well as reduced sensitivity to chemotherapeutics, increased stress-induced autophagic flux, decreased apoptosis and upregulation of autophagy-related genes after 5-FU treatment. However, inactivation of singular miR-34a or miR-34b/c had little effects on the aforementioned processes. RNA-Seq analysis revealed that concomitant deletion of miR-34a/b/c caused EMT signature enrichment, impaired gene repression by the p53-DREAM pathway and elevated autophagy after 5-FU treatment. A gene signature comprised of mRNAs significantly upregulated after combined inactivation of miR-34a and miR-34b/c showed a significant association with the invasive colon cancer subtype CMS4 and poor overall survival in two CRC patient cohorts, and with 5-FU resistance in CRC cell lines. In miR-34a/b/c-deficient cells the upregulated miR-34 target FOXM1 directly induced p62 and ATG9A, which increased autophagy and consequently attenuated apoptosis and rendered the miR-34a/b/c-KO cells more resistant to 5-FU. Inhibition of autophagy by depletion of ATG9A or chloroquine re-sensitized miR-34a/b/c-deficient HCT116 cells to 5-FU. In summary, our findings show a complementary role of miR-34a and miR-34b/c in the regulation of EMT and autophagy which may be relevant for CRC therapy in the future.

Functional In Vivo Screening Identifies microRNAs Regulating Metastatic Dissemination of Prostate Cancer Cells to Bone Marrow

Distant metastasis is the major cause of cancer-related deaths in men with prostate cancer (PCa). An in vivo functional screen was used to identify microRNAs (miRNAs) regulating metastatic dissemination of PCa cells. PC3 cells transduced with pooled miRZiP™ lentivirus library (anti-miRNAs) were injected intraprostatic to 13 NSG mice followed by targeted barcode/anti-miR sequencing. PCa cells in the primary tumours showed a homogenous pattern of anti-miRNAs, but different anti-miRNAs were enriched in liver, lung, and bone marrow, with anti-miR-379 highly enriched in the latter. The bone metastasis-promoting phenotype induced by decreased miR-379 levels was also confirmed in a less metastatic PCa cell line, 22Rv1, where all mice injected intracardially with anti-miR-379-22Rv1 cells developed bone metastases. The levels of miR-379 were found to be lower in bone metastases compared to primary tumours and non-cancerous prostatic tissue in a patient cohort. In vitro functional studies suggested that the mechanism of action was that reduced levels of miR-379 gave an increased colony formation capacity in conditions mimicking the bone microenvironment. In conclusion, our data suggest that specific miRNAs affect the establishment of primary tumours and metastatic dissemination, with a loss of miR-379 promoting metastases in bone.

Can Dietary Actives Affect miRNAs and Alter the Course or Prevent Colorectal Cancer?

Colorectal cancer is a diet-related cancer. There is much research into the effects of nutrients on the prevention, modulation, and treatment of colorectal cancer. Researchers are trying to find a correlation between epidemiological observations indicating certain dietary components as the originator in the process of developing colorectal cancer, such as a diet rich in saturated animal fats, and dietary components that could eliminate the impact of harmful elements of the daily nutritional routine, i.e., substances such as polyunsaturated fatty acids, curcumin, or resveratrol. Nevertheless, it is very important to understand the mechanisms underlying how food works on cancer cells. In this case, microRNA (miRNA) seems to be a very significant research target. MiRNAs participate in many biological processes connected to carcinogenesis, progression, and metastasis. However, this is a field with development prospects ahead. In this paper, we review the most significant and well-studied food ingredients and their effects on various miRNAs involved in colorectal cancer.

Unpacking the Complexity of Epithelial Plasticity: From Master Regulator Transcription Factors to Non-Coding RNAs

Cellular plasticity in cancer enables adaptation to selective pressures and stress imposed by the tumor microenvironment. This plasticity facilitates the remodeling of cancer cell phenotype and function (such as tumor stemness, metastasis, chemo/radio resistance), and the reprogramming of the surrounding tumor microenvironment to enable immune evasion. Epithelial plasticity is one form of cellular plasticity, which is intrinsically linked with epithelial-mesenchymal transition (EMT). Traditionally, EMT has been regarded as a binary state. Yet, increasing evidence suggests that EMT involves a spectrum of quasi-epithelial and quasi-mesenchymal phenotypes governed by complex interactions between cellular metabolism, transcriptome regulation, and epigenetic mechanisms. Herein, we review the complex cross-talk between the different layers of epithelial plasticity in cancer, encompassing the core layer of transcription factors, their interacting epigenetic modifiers and non-coding RNAs, and the manipulation of cancer immunogenicity in transitioning between epithelial and mesenchymal states. In examining these factors, we provide insights into promising therapeutic avenues and potential anti-cancer targets.

EMT/MET plasticity in cancer and Go-or-Grow decisions in quiescence: the two sides of the same coin?

Epithelial mesenchymal transition (EMT) and mesenchymal epithelial transition (MET) are genetic determinants of cellular plasticity. These programs operate in physiological (embryonic development, wound healing) and pathological (organ fibrosis, cancer) conditions. In cancer, EMT and MET interfere with various signalling pathways at different levels. This results in gross alterations in the gene expression programs, which affect most, if not all hallmarks of cancer, such as response to proliferative and death-inducing signals, tumorigenicity, and cell stemness. EMT in cancer cells involves large scale reorganisation of the cytoskeleton, loss of epithelial integrity, and gain of mesenchymal traits, such as mesenchymal type of cell migration. In this regard, EMT/MET plasticity is highly relevant to the Go-or-Grow concept, which postulates the dichotomous relationship between cell motility and proliferation. The Go-or-Grow decisions are critically important in the processes in which EMT/MET plasticity takes the central stage, mobilisation of stem cells during wound healing, cancer relapse, and metastasis. Here we outline the maintenance of quiescence in stem cell and metastatic niches, focusing on the implication of EMT/MET regulatory networks in Go-or-Grow switches. In particular, we discuss the analogy between cells residing in hybrid quasi-mesenchymal states and G_Alert, an intermediate phase allowing quiescent stem cells to enter the cell cycle rapidly.

Curcumin activates a ROS/KEAP1/NRF2/miR-34a/b/c cascade to suppress colorectal cancer metastasis

Curcumin, a natural phytochemical isolated from tumeric roots, represents a candidate for prevention and therapy of colorectal cancer/CRC. However, the exact mechanism of action and the downstream mediators of curcumin's tumor suppressive effects have remained largely unknown. Here we used a genetic approach to determine the role of the p53/miR-34 pathway as mediator of the effects of curcumin. Three isogenic CRC cell lines rendered deficient for the p53, miR-34a and/or miR-34b/c genes were exposed to curcumin and subjected to cell biological analyses. siRNA-mediated inhibition and ectopic expression of NRF2, as well as Western blot, qPCR and qChIP analyses of its target genes were performed. CRC cells were i.v. injected into NOD/SCID mice and lung-metastases formation was determined by longitudinal, non-invasive imaging. In CRC cells curcumin induced apoptosis and senescence, and suppressed migration and invasion in a p53-independent manner. Curcumin activated the KEAP1/NRF2/ARE pathway by inducing ROS. Notably, curcumin induced miR-34a and miR-34b/c expression in a ROS/NRF2-dependent and p53-independent manner. NRF2 directly induced miR-34a and miR-34b/c via occupying multiple ARE motifs in their promoter regions. Curcumin reverted repression of miR-34a and miR-34b/c induced by IL6 and hypoxia. Deletion of miR-34a and miR-34b/c significantly reduced curcumin-induced apoptosis and senescence, and prevented the inhibition of migration and invasion by curcumin or ectopic NRF2. In CRC cells curcumin induced MET and prevented the formation of lung-metastases in mice in a miR-34a-dependent manner. In addition, we found that curcumin may enhance the therapeutic effects of 5-FU on CRC cells deficient for p53 and miR-34a/b/c. Activation of the KEAP1/NRF2/miR-34a/b/c axis mediates the tumor suppressive activity of curcumin and suggests a new approach for activating miR-34 genes in tumors for therapeutic purposes.

Exosomes in metastasis of colorectal cancers: Friends or foes?

Colorectal cancer (CRC), the third most common type of cancer worldwide, threaten human health and quality of life. With multidisciplinary, including surgery, chemotherapy and/or radiotherapy, patients with an early diagnosis of CRC can have a good prognosis. However, metastasis in CRC patients is the main risk factor causing cancer-related death. To elucidate the underlying molecular mechanisms of CRC metastasis is the difficult and research focus on the investigation of the CRC mechanism. On the other hand, the tumor microenvironment (TME) has been confirmed as having an essential role in the tumorigenesis and metastasis of malignancies, including CRCs. Among the different factors in the TME, exosomes as extracellular vesicles, function as bridges in the communication between cancer cells and different components of the TME to promote the progression and metastasis of CRC. MicroRNAs packaged in exosomes can be derived from different sources and transported into the TME to perform oncogenic or tumor-suppressor roles accordingly. This article focuses on CRC exosomes and illustrates their role in regulating the metastasis of CRC, especially through the packaging of miRNAs, to evoke exosomes as novel biomarkers for their impact on the metastasis of CRC progression.

Targeted therapy using nanocomposite delivery systems in cancer treatment: highlighting miR34a regulation for clinical applications

The clinical application of microRNAs in modern therapeutics holds great promise to uncover molecular limitations and conquer the unbeatable castle of cancer metastasis. miRNAs play a decisive role that regulating gene expression at the post-transcription level while controlling both the stability and translation capacity of mRNAs. Specifically, miR34a is a master regulator of the tumor suppressor gene, cancer progression, stemness, and drug resistance at the cell level in p53-dependent and independent signaling. With changing, trends in nanotechnology, in particular with the revolution in the field of nanomedicine, nano drug delivery systems have emerged as a prominent strategy in clinical practices coupled with miR34a delivery. Recently, it has been observed that forced miR34a expression in human cancer cell lines and model organisms limits cell proliferation and metastasis by targeting several signaling cascades, with various studies endorsing that miR34a deregulation in cancer cells modulates apoptosis and thus requires targeted nano-delivery systems for cancer treatment. In this sense, the present review aims to provide an overview of the clinical applications of miR34a regulation in targeted therapy of cancer.

A role for partial epithelial-to-mesenchymal transition in enabling stemness in homeostasis and cancer

Stem cells have self-renewal capacities and the ability to give rise to differentiated cells thereby sustaining tissues during homeostasis and injury. This structural hierarchy extends to tumours which harbor stem-like cells deemed cancer stem cells that propagate the tumour and drive metastasis and relapse. The process of epithelial-to-mesenchymal transition (EMT), which plays an important role in development and cancer cell migration, was shown to be correlated with stemness in both homeostasis and cancer indicating that stemness can be acquired and is not necessarily an intrinsic trait. Nowadays it is experimentally proven that the activation of an EMT program does not necessarily drive cells towards a fully mesenchymal phenotype but rather to hybrid E/M states. This review offers the latest advances in connecting the EMT status and stem-cell state of both non-transformed and cancer cells. Recent literature clearly shows that hybrid EMT states have a higher probability of acquiring stem cell traits. The position of a cell along the EMT-axis which coincides with a stem cell-like state is known as the stemness window. We show how the original EMT-state of a cell dictates the EMT/MET inducing programmes required to reach stemness. Lastly we present the mechanism of stemness regulation and the regulatory feedback loops which position cells at a certain EMT state along the EMT axis.

The role of LIN28B in tumor progression and metastasis in solid tumor entities

LIN28B is an RNA-binding protein that targets a broad range of microRNAs and modulates their maturation and activity. Under normal conditions, LIN28B is exclusively expressed in embryogenic stem cells, blocking differentiation and promoting proliferation. In addition, it can play a role in epithelial-to-mesenchymal transition by repressing the biogenesis of let-7 microRNAs. In malignancies, LIN28B is frequently overexpressed, which is associated with increased tumor aggressiveness and metastatic properties. In this review, we discuss the molecular mechanisms of LIN28B in promoting tumor progression and metastasis in solid tumor entities and its potential use as a clinical therapeutic target and biomarker.

EMT-activated secretory and endocytic vesicular trafficking programs underlie a vulnerability to PI4K2A antagonism in lung cancer

Hypersecretory malignant cells underlie therapeutic resistance, metastasis, and poor clinical outcomes. However, the molecular basis for malignant hypersecretion remains obscure. Here, we showed that epithelial-mesenchymal transition (EMT) initiates exocytic and endocytic vesicular trafficking programs in lung cancer. The EMT-activating transcription factor zinc finger E-box-binding homeobox 1 (ZEB1) executed a PI4KIIIβ-to-PI4KIIα (PI4K2A) dependency switch that drove PI4P synthesis in the Golgi and endosomes. EMT enhanced the vulnerability of lung cancer cells to PI4K2A small-molecule antagonists. PI4K2A formed a MYOIIA-containing protein complex that facilitated secretory vesicle biogenesis in the Golgi, thereby establishing a hypersecretory state involving osteopontin (SPP1) and other prometastatic ligands. In the endosomal compartment, PI4K2A accelerated recycling of SPP1 receptors to complete an SPP1-dependent autocrine loop and interacted with HSP90 to prevent lysosomal degradation of AXL receptor tyrosine kinase, a driver of cell migration. These results show that EMT coordinates exocytic and endocytic vesicular trafficking to establish a therapeutically actionable hypersecretory state that drives lung cancer progression.

Tumor cell plasticity in targeted therapy-induced resistance: mechanisms and new strategies

Despite the success of targeted therapies in cancer treatment, therapy-induced resistance remains a major obstacle to a complete cure. Tumor cells evade treatments and relapse via phenotypic switching driven by intrinsic or induced cell plasticity. Several reversible mechanisms have been proposed to circumvent tumor cell plasticity, including epigenetic modifications, regulation of transcription factors, activation or suppression of key signaling pathways, as well as modification of the tumor environment. Epithelial-to-mesenchymal transition, tumor cell and cancer stem cell formation also serve as roads towards tumor cell plasticity. Corresponding treatment strategies have recently been developed that either target plasticity-related mechanisms or employ combination treatments. In this review, we delineate the formation of tumor cell plasticity and its manipulation of tumor evasion from targeted therapy. We discuss the non-genetic mechanisms of targeted drug-induced tumor cell plasticity in various types of tumors and provide insights into the contribution of tumor cell plasticity to acquired drug resistance. New therapeutic strategies such as inhibition or reversal of tumor cell plasticity are also presented. We also discuss the multitude of clinical trials that are ongoing worldwide with the intention of improving clinical outcomes. These advances provide a direction for developing novel therapeutic strategies and combination therapy regimens that target tumor cell plasticity.

Heterogeneity and plasticity of epithelial-mesenchymal transition (EMT) in cancer metastasis: Focusing on partial EMT and regulatory mechanisms

Epithelial-mesenchymal transition (EMT) or mesenchymal-epithelial transition (MET) plays critical roles in cancer metastasis. Recent studies, especially those based on single-cell sequencing, have revealed that EMT is not a binary process, but a heterogeneous and dynamic disposition with intermediary or partial EMT states. Multiple double-negative feedback loops involved by EMT-related transcription factors (EMT-TFs) have been identified. These feedback loops between EMT drivers and MET drivers finely regulate the EMT transition state of the cell. In this review, the general characteristics, biomarkers and molecular mechanisms of different EMT transition states were summarized. We additionally discussed the direct and indirect roles of EMT transition state in tumour metastasis. More importantly, this article provides direct evidence that the heterogeneity of EMT is closely related to the poor prognosis in gastric cancer. Notably, a seesaw model was proposed to explain how tumour cells regulate themselves to remain in specific EMT transition states, including epithelial state, hybrid/intermediate state and mesenchymal state. Additionally, this article also provides a review of the current status, limitations and future perspectives of EMT signalling in clinical applications.

Single-copy Snail upregulation causes partial epithelial-mesenchymal transition in colon cancer cells

BACKGROUND

Epithelial-mesenchymal transition (EMT) is an embryonic programme implicated in cancer stem cells, metastasis and therapeutic resistance. Its role in cancer progression remains controversial because the transition can be partial or complete in different models and contexts.

METHODS

Using human colon cancer DLD-1 cells, we engineered a cell line with a single-copy of Snail that was doxycycline-inducible and compared it to existing EMT models in DLD-1. The effect of Snail upregulation was characterised functionally, morphologically, and by transcriptional profiling and protein expression.

RESULTS

Induction with doxycycline increased Snail expression to a level similar to that observed in cancer cell lines spontaneously expressing Snail and results in partial EMT. In comparison, higher levels of overexpression arising from introduction of episomal-Snail, results in complete EMT. DLD-1 cells with partial EMT show chemoresistance in vitro, increased tumour growth in vivo and decreased apoptosis.

CONCLUSIONS

These findings highlight that the amount of bioavailable Snail can dictate phenotypic outcome and that partial EMT may be a preferred outcome of models operating within a natural range of Snail overexpression.

In silico analysis reveals hypoxia-induced miR-210-3p specifically targets SARS-CoV-2 RNA

Human coronaviruses (HCoVs) until the emergence of SARS in 2003 were associated with mild cold and upper respiratory tract infections. The ongoing pandemic caused by SARS-CoV-2 has enhanced the potential for infection and transmission as compared to other known members of this family. MicroRNAs (miRNA) are 21-25 nucleotides long non-coding RNA that bind to 3' UTR of genes and regulate almost every aspect of cellular function. Several human miRNAs have been known to target viral genomes, mostly to downregulate their expression and sometimes to upregulate also. In some cases, host miRNAs could be sequestered by the viral genome to create a condition for favourable virus existence. The ongoing SARS CoV-2 pandemic is unique based on its transmissibility and severity and we hypothesised that there could be a unique mechanism for its pathogenesis. In this study, we exploited in silico approach to identify human respiratory system-specific miRNAs targeting the viral genome of three highly pathogenic HCoVs (SARS-CoV-2 Wuhan strain, SARS-CoV, and MERS-CoV) and three low pathogenic HCoVs (OC43, NL63, and HKU1). We identified ten common microRNAs that target all HCoVs studied here. In addition, we identified unique miRNAs which targeted specifically one particular HCoV. miR-210-3p was the single unique lung-specific miRNA, which was found to target the NSP3, NSP4, and NSP13 genes of SARS-CoV-2. Further miR-210-NSP3, miR-210-NSP4, and miR-210-NSP13 SARS-CoV-2 duplexes were docked with the hAGO2 protein (PDB ID 4F3T) which showed Z-score values of -1.9, -1.7, and -1.6, respectively. The role of miR-210-3p as master hypoxia regulator and inflammation regulation may be important for SARS-CoV-2 pathogenesis. Overall, this analysis advocates that miR-210-3p be investigated experimentally in SARS-CoV-2 infection.Communicated by Ramaswamy H. Sarma.

Dynamic changes of the EMT spectrum between circulating tumor cells and the tumor microenvironment in human papillomavirus-positive head and neck squamous cell carcinoma

OBJECTIVES

Human papillomavirus (HPV)-positive head and neck squamous cell carcinoma (HNSCC) differs in terms of cellular and molecular biological characteristics from HPV-negative HNSCC. However, differences in circulating tumor cells (CTCs) between HPV-positive and -negative HNSCC remain unclear.

MATERIALS AND METHODS

We first analyzed eight epithelial-mesenchymal transition (EMT)-related genes (VIM, CDH1, CDH2, SNAI1, SNAI2, TWIST1, ZEB1, and ZEB2) using The Cancer Genome Atlas (TCGA) database. Next, we isolated CTCs from patients with HNSCC using CD45-negative selection and expression analysis of epithelial-related genes (EPCAM, EGFR, and MET) by RT-qPCR. CTC-positive samples were further analyzed for EMT-related genes. In addition, we investigated the proportion of circulating T cell subsets and CD38+ T cells using flow cytometry and their involvement in CTCs.

RESULTS

Compared with HPV-negative HNSCC, expression of CDH1, SNAI1, SNAI2, TWIST1, and ZEB1 was downregulated in HPV-positive HNSCC, as determined by TCGA analysis. CTCs were detected in 19 (52.8 %) of 36 HPV-positive and 26 (68.4 %) of 38 HPV-negative patients with HNSCC. EPCAM-positive and MET-positive CTCs were significantly more frequent in patients with HPV-negative HNSCC. HPV-positive patients with HNSCC exhibited significantly high SNAI1 and ZEB2 expression in CTCs. Interestingly, differences in SNAI1 expression levels differed markedly between CTCs and TCGA based on HPV status. Moreover, HPV-positive patients with HNSCC exhibiting SNAI1-high CTCs showed a superior prognosis and a lower proportion of CD38+ T cells than those with SNAI1-low CTCs.

CONCLUSION

Our results provide novel insights into the EMT-MET spectrum of CTCs and may contribute to the development of prognostic biomarkers for HPV-positive HNSCC.

A comprehensive review on RNA interference-mediated targeting of interleukins and its potential therapeutic implications in colon cancer

Colon cancer is the world's fourth leading cause of death. It is cancer of the latter part of the large intestine, i.e. the colon. Chronic inflammation over a long period also leads to the development of cancer. Cancer in the colon region is arduous to diagnose and is detected at a later stage when it metastasizes to other parts of the body like the liver, lungs, peritoneum, etc. Colon cancer is a great example of solid tumours associated with chronic inflammation. Although conventional therapies are effective, they lose their effectiveness beyond a certain point. Relapse of the disease occurs frequently. RNA interference (RNAi) is emerging as a great tool to specifically attack the cancer cells of a target site like the colon. RNAi deals with epigenetic changes made in the defective cells which ultimately leads to their death without harming the healthy cells. In this review, two types of epigenetic modulators have been considered, namely siRNA and miRNA, and their effect on interleukins. Interleukins, a class of cytokines, are major inflammatory responses of the body that are released by immune cells like leukocytes and macrophages. Some of these interleukins are pro-inflammatory, thereby promoting inflammation which eventually causes cancer. RNAi can prevent colon cancer by inhibiting pro-inflammatory interleukins.

Regulation of epithelial-mesenchymal transition by tumor microenvironmental signals and its implication in cancer therapeutics

Epithelial-mesenchymal transition (EMT) has been implicated in various aspects of tumor development, including tumor invasion and metastasis, cancer stemness, and therapy resistance. Diverse stroma cell types along with biochemical and biophysical factors in the tumor microenvironment impinge on the EMT program to impact tumor progression. Here we provide an in-depth review of various tumor microenvironmental signals that regulate EMT in cancer. We discuss the molecular mechanisms underlying the role of EMT in therapy resistance and highlight new therapeutic approaches targeting the tumor microenvironment to impact EMT and tumor progression.

Innate Immunity, Epithelial Plasticity, and Remodeling in Asthma

Innate immune responses (IIR) of the epithelium play a critical role in the initiation and progression of asthma. The core of the IIR is an intracellular signaling pathway activated by pattern recognition receptors (PRRs) to limit the spread of infectious organisms. This chapter will focus on the epithelium as the major innate sentinel cell and its role in acute exacerbations (AEs). Although the pathways of how the IIR activates the NFκB transcription factor, triggering cytokine secretion, dendritic cell activation, and Th2 polarization are well-described, recent exciting work has developed mechanistic insights into how chronic activation of the IIR is linked to mucosal adaptive responses. These adaptations include changes in cell state, now called epithelial-mesenchymal plasticity (EMP). EMP is a coordinated, genomic response to airway injury disrupting epithelial barrier function, expanding the basal lamina, and producing airway remodeling. EMP is driven by activation of the unfolded protein response (UPR), a transcriptional response producing metabolic shunting of glucose through the hexosamine biosynthetic pathway (HBP) to protein N-glycosylation. NFκB signaling and UPR activation pathways potentiate each other in remodeling the basement membrane. Understanding of injury-repair process of epithelium provides new therapeutic targets for precision approaches to the treatment of asthma exacerbations and their sequelae.

Therapeutic potential of targeting mirnas to prostate cancer tumors: using psma as an active target

Prostate cancer (PC) is a commonly diagnosed malignancy in men and is associated with high mortality rates. Current treatments for PC include surgery, chemotherapy, and radiation therapy. However, recent advances in targeted delivery systems have yielded promising new approaches to PC treatment. As PC epithelial cells express high levels of prostate-specific membrane antigen (PSMA) on the cell surface, new drug conjugates focused on PSMA targeting have been developed. microRNAs (miRNAs) are small noncoding RNAs that regulate posttranscriptional gene expression in cells and show excellent possibilities for use in developing new therapeutics for PC. PSMA-targeted therapies based on a miRNA payload and that selectively target PC cells enhances therapeutic efficacy without eliciting damage to normal surrounding tissue. This review discusses the rationale for utilizing miRNAs to target PSMA, revealing their potential in therapeutic approaches to PC treatment. Different delivery systems for miRNAs and challenges to miRNA therapy are also explored.

Meta-analysis of miR-34 target mRNAs using an integrative online application

Members of the microRNA-34/miR-34 family are induced by the p53 tumor suppressor and themselves possess tumor suppressive properties, as they inhibit the translation of mRNAs that encode proteins involved in processes, such as proliferation, migration, invasion, and metastasis. Here we performed a comprehensive integrative meta-analysis of multiple computational and experimental miR-34 related datasets and developed tools to identify and characterize novel miR-34 targets. A miR-34 target probability score was generated for every mRNA to estimate the likelihood of representing a miR-34 target. Experimentally validated miR-34 targets were strongly enriched among mRNAs with the highest scores providing a proof of principle for our analysis. We integrated the results from the meta-analysis in a user-friendly METAmiR34TARGET website (www.metamir34target.com/) that allows to graphically represent the meta-analysis results for every mRNA. Moreover, the website harbors a screen function, which allows to select multiple miR-34-related criteria/analyses and cut-off values to facilitate the stringent and comprehensive prediction of relevant miR-34 targets in expression data obtained from cell lines and tumors/tissues. Furthermore, information on more than 200 miR-34 target mRNAs, that have been experimentally validated so far, has been integrated in the web-tool. The website and datasets provided here should facilitate further investigation into the mechanisms of tumor suppression by the p53/miR-34 connection and identification of potential cancer drug targets.

Hsa-microRNA-370-3p targeting Snail and Twist1 suppresses IL-8/STAT3-driven hepatocellular carcinoma metastasis

The pro-inflammatory factor interleukin-8 (IL-8) is related to poor prognosis in hepatocellular carcinoma (HCC) patients. Interleukin-8 enhanced HCC invasion by upregulating Snail and Twist1, whether this modulation relies on microRNAs (miR) is unclear. In this study, hsa-miR-370-3p was screened as candidate miRNA targeting Snail and Twist1, and its expression was downregulated by IL-8. Luciferase assays and RNA electrophoretic mobility shift assays were used to evaluate the interaction between miR-370-3p and targeted mRNAs. Coimmunoprecipitation, luciferase, and ChIP assays were undertaken to investigate the mechanisms underlying IL-8-mediated modification of miR-370-3p. Gain- and loss-of-function studies, Transwell assays, and a xenograft nude mouse model were used to investigate pro- and antitumor activities. Interleukin-8 and miR-370-3p levels were analyzed for clinical relevance in HCC patients. Our results showed that HCC patients with high levels of IL-8 experienced more metastasis and shorter survival. Interleukin-8 induced epithelial-mesenchymal transition and promoted liver cancer cell migration, invasion, and metastasis both in vitro and in vivo. MicroRNA-370-3p interacted with its cognate mRNA within the 3'-UTR regions of Twist1 and Snail mRNA directly and specifically and attenuated IL-8 protumoral effects on liver cancer cells. Interleukin-8 negatively modulated miR-370-3p through signal transducer and activator of transcription 3 (STAT3) activation by recruiting histone deacetylase 1 (HDAC1) to miR-370-3p promoter. The STAT3 and HDAC antagonists inhibited liver cancer cell migration and invasion. Patients with high miR-370-3p and low IL-8 levels had longer overall survival. In conclusion, our study elucidated a novel axis IL-8/STAT3/miR-370-3p/Twist1 and Snail relying on HDAC1 recruitment, which showed both diagnostic and therapeutic potentials of miR-370-3p in HCC metastasis.

Non-coding RNAs and epithelial mesenchymal transition in cancer: molecular mechanisms and clinical implications

Epithelial-mesenchymal transition (EMT) is a fundamental process for embryonic development during which epithelial cells acquire mesenchymal characteristics, and the underlying mechanisms confer malignant features to carcinoma cells such as dissemination throughout the organism and resistance to anticancer treatments. During the past decades, an entire class of molecules, called non-coding RNA (ncRNA), has been characterized as a key regulator of almost every cellular process, including EMT. Like protein-coding genes, ncRNAs can be deregulated in cancer, acting as oncogenes or tumor suppressors. The various forms of ncRNAs, including microRNAs, PIWI-interacting RNAs, small nucleolar RNAs, transfer RNA-derived RNA fragments, long non-coding RNAs, and circular RNAs can orchestrate the complex regulatory networks of EMT at multiple levels. Understanding the molecular mechanism underlying ncRNAs in EMT can provide fundamental insights into cancer metastasis and may lead to novel therapeutic approaches. In this review, we describe recent advances in the understanding of ncRNAs in EMT and provide an overview of recent ncRNA applications in the clinic.

The molecular mechanisms and therapeutic strategies of EMT in tumor progression and metastasis

Epithelial–mesenchymal transition (EMT) is an essential process in normal embryonic development and tissue regeneration. However, aberrant reactivation of EMT is associated with malignant properties of tumor cells during cancer progression and metastasis, including promoted migration and invasiveness, increased tumor stemness, and enhanced resistance to chemotherapy and immunotherapy. EMT is tightly regulated by a complex network which is orchestrated with several intrinsic and extrinsic factors, including multiple transcription factors, post-translational control, epigenetic modifications, and noncoding RNA-mediated regulation. In this review, we described the molecular mechanisms, signaling pathways, and the stages of tumorigenesis involved in the EMT process and discussed the dynamic non-binary process of EMT and its role in tumor metastasis. Finally, we summarized the challenges of chemotherapy and immunotherapy in EMT and proposed strategies for tumor therapy targeting EMT.

Long noncoding RNA SNHG7-miRNA-mRNA axes crosstalk with oncogenic signaling pathways in human cancers

LncRNAs and miRNAs are the two most important non-coding RNAs, which have been identified to be associated with cancer progression or prevention. The dysregulation of lncRNAs conducts tumorigenesis and metastasis in different ways. One of the mechanisms is that lncRNAs interact with miRNAs to regulate distinct cellular and genomic processes and cancer progression. LncRNA SNHG7 as an oncogene sponges miRNAs and develops lncRNA-miRNA-mRNA axes, leading to the regulation of several signaling pathways such as Wnt/β-Catenin, PI3K/AKT/mTOR, SIRT1, and Snail-EMT. Therefore, in this article, after a brief overview of lncRNA SNHG7-miRNA-mRNA axes' contribution to cancer development, we will discuss the role of lncRNA SNHG7 in the genes expression and signaling pathways related to cancers development via acting as a ceRNA.

Engaging plasticity: Differentiation therapy in solid tumors

Cancer is a systemic heterogeneous disease that can undergo several rounds of latency and activation. Tumor progression evolves by increasing diversity, adaptation to signals from the microenvironment and escape mechanisms from therapy. These dynamic processes indicate necessity for cell plasticity. Epithelial-mesenchymal transition (EMT) plays a major role in facilitating cell plasticity in solid tumors by inducing dedifferentiation and cell type transitions. These two practices, plasticity and dedifferentiation enhance tumor heterogeneity creating a key challenge in cancer treatment. In this review we will explore cancer cell plasticity and elaborate treatment modalities that aspire to overcome such dynamic processes in solid tumors. We will further discuss the therapeutic potential of utilizing enhanced cell plasticity for differentiation therapy.

miRNA-34c-5p targets Fra-1 to inhibit pulmonary fibrosis induced by silica through p53 and PTEN/PI3K/Akt signaling pathway

Silica dust particles are representative of air pollution and long-term inhalation of silicon-containing dust through the respiratory tract can cause pulmonary fibrosis. Epithelial-mesenchymal transformation (EMT) plays an important role in the development of fibrosis. This process can relax cell-cell adhesion complexes and enhance cell migration and invasion properties of these cells. Dysregulation of microRNA-34c (miR-34c) is highly correlated with organ fibrosis including pulmonary fibrosis. In this study, we found that miR-34c-5p could alleviate the occurrence and development of silica-mediated EMT. Fos-related antigen 1 was identified as a functional target of miR-34c-5p by bioinformatics analysis and the dual luciferase gene reporting assay. Importantly, chemically induced up-regulation of hsa-miR-34c-5p correlated inversely with the expression of Fra-1 and further exploration found that the miR-34c-5p/Fra-1 axis inhibits the activation of the phosphatase and tensin homolog deleted on chromosome 10/phosphatidylinositol-4,5-bisphosphate3-kinase/protein kinase B (PTEN/PI3K/AKT) signaling pathway. In addition, through interaction with PTEN/p53 it inhibits the proliferation and migration of human bronchial epithelial cells stimulated by silica, and promotes cell apoptosis, thereby preventing EMT. This finding provides a promising biomarker for the diagnosis and prognosis of pulmonary fibrosis. Furthermore, overexpression of miR-34c-5p represents a potential therapeutic approach.

SNAIL driven by a feed forward loop motif promotes TGFβinduced epithelial to mesenchymal transition

Epithelial to Mesenchymal Transition (EMT) plays an important role in tissue regeneration, embryonic development, and cancer metastasis. Several signaling pathways are known to regulate EMT, among which the modulation of TGFβ(Transforming Growth Factor-β) induced EMT is crucial in several cancer types. Several mathematical models were built to explore the role of core regulatory circuit of ZEB/miR-200, SNAIL/miR-34 double negative feedback loops in modulating TGFβinduced EMT. Different emergent behavior including tristability, irreversible switching, existence of hybrid EMT states were inferred though these models. Some studies have explored the role of TGFβreceptor activation, SMADs nucleocytoplasmic shuttling and complex formation. Recent experiments have revealed that MDM2 along with SMAD complex regulates SNAIL expression driven EMT. Encouraged by this, in the present study we developed a mathematical model for p53/MDM2 dependent TGFβinduced EMT regulation. Inclusion of p53 brings in an additional mechanistic perspective in exploring the EM transition. The network formulated comprises a C1FFL moderating SNAIL expression involving MDM2 and SMAD complex, which functions as a noise filter and persistent detector. The C1FFL was also observed to operate as a coincidence detector driving the SNAIL dependent downstream signaling into phenotypic switching decision. Systems modelling and analysis of the devised network, displayed interesting dynamic behavior, systems response to various inputs stimulus, providing a better understanding of p53/MDM2 dependent TGF-βinduced Epithelial to Mesenchymal Transition.

Opposing Roles of Wild-type and Mutant p53 in the Process of Epithelial to Mesenchymal Transition

The central role of an aberrantly activated EMT program in defining the critical features of aggressive carcinomas is well documented and includes cell plasticity, metastatic dissemination, drug resistance, and cancer stem cell-like phenotypes. The p53 tumor suppressor is critical for leashing off all the features mentioned above. On the molecular level, the suppression of these effects is exerted by p53 via regulation of its target genes, whose products are involved in cell cycle, apoptosis, autophagy, DNA repair, and interactions with immune cells. Importantly, a set of specific mutations in the TP53 gene (named Gain-of-Function mutations) converts this tumor suppressor into an oncogene. In this review, we attempted to contrast different regulatory roles of wild-type and mutant p53 in the multi-faceted process of EMT.

The Role of MicroRNA in the Regulation of Tumor Epithelial–Mesenchymal Transition

Consistently, the high metastasis of cancer cells is the bottleneck in the process of tumor treatment. In this process of metastasis, a pivotal role is executed by epithelial–mesenchymal transition (EMT). The epithelial-to-mesenchymal transformation was first proposed to occur during embryonic development. Later, its important role in explaining embryonic developmental processes was widely reported. Recently, EMT and its intermediate state were also identified as crucial drivers in tumor progression with the gradual deepening of research. To gain insights into the potential mechanism, increasing attention has been focused on the EMT-related transcription factors. Correspondingly, miRNAs target transcription factors to control the EMT process of tumor cells in different types of cancers, while there are still many exciting and challenging questions about the phenomenon of microRNA regulation of cancer EMT. We describe the relevant mechanisms of miRNAs regulating EMT, and trace the regulatory roles and functions of major EMT-related transcription factors, including Snail, Twist, zinc finger E-box-binding homeobox (ZEB), and other families. In addition, on the basis of the complex regulatory network, we hope that the exploration of the regulatory relationship of non-transcription factors will provide a better understanding of EMT and cancer metastasis. The identification of the mechanism leading to the activation of EMT programs during diverse disease processes also provides a new protocol for the plasticity of distinct cellular phenotypes and possible therapeutic interventions. Here, we summarize the recent progress in this direction, with a promising path for further insight into this fast-moving field.

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.

Exosomal microRNAs synergistically trigger stromal fibroblasts in breast cancer

Triple-negative breast cancer (TNBC) is the most aggressive breast cancer subtype. TNBC progression is sustained by recruitment of a strong tumor microenvironment (TME) mainly composed of cancer-associated fibroblasts (CAFs) able to endorse tumor hallmarks. Increasing evidences demonstrate that exosomes mediate the crosstalk between cancer cells and the TME. We examined TNBC-derived exosomes and their microRNA (miRNA) cargo in activation of normal fibroblasts (NFs) toward CAFs. We demonstrated that TNBC cell-derived exosomes increased NF collagen contraction and migration alongside CAF molecular markers. Exosome-activated fibroblasts promoted the invasion potential of normal breast epithelial cells, as assessed by an organotypic co-culture assay that resembled the in vivo context. We also investigated TNBC cell-derived exosome cargo in activating NFs to CAFs by performing small RNA sequencing. We found that the synergistic action of miR-185-5p, miR-652-5p, and miR-1246 boosted fibroblast migration and contraction, promoting specific CAF subspecialization toward a pro-migratory functional state. These data highlight the role of breast cancer cells in re-education of the TME and their contribution to tumor evolution.

The Wnt pathway can stabilize hybrid phenotypes in the epithelial-mesenchymal transition: A logical modeling approach

The Wnt pathway is important to regulate a variety of biochemical functions and can contribute to cancer development through its influence on the epithelial-mesenchymal transition (EMT). Multiple circuits have been reported to participate in the regulation of the Wnt signaling, however, the way these circuits coordinately regulate this signaling is still unclear. Moreover, the mechanisms responsible for the appearance of hybrid phenotypes (cells presenting both E and M features) are not well determined. The hybrid phenotype can present much higher metastatic potential than the mesenchymal phenotype. In this study, we propose a Boolean model of the Wnt pathway signaling contemplating recent published biochemical information on hepatocarcinoma. The model presents good coherence with experimental data for perturbed and wild-type cases. With the model, we propose two new molecular circuits involving several molecules that can stabilize hybrid states during the EMT. Moreover, we found that the two well studied circuits, AKT1/β-catenin and SNAIL1/miR-34, can cooperate with the predicted ones to favor the stabilization of the hybrid states. These findings highlight some possible unrecognized mechanisms during Wnt signaling and may provide alternative therapeutic strategies to control cancer metastatization.

Sirtuins and Hypoxia in EMT Control

Epithelial–mesenchymal transition (EMT), a physiological process during embryogenesis, can become pathological in the presence of different driving forces. Reduced oxygen tension or hypoxia is one of these forces, triggering a large number of molecular pathways with aberrant EMT induction, resulting in cancer and fibrosis onset. Both hypoxia-induced factors, HIF-1α and HIF-2α, act as master transcription factors implicated in EMT. On the other hand, hypoxia-dependent HIF-independent EMT has also been described. Recently, a new class of seven proteins with deacylase activity, called sirtuins, have been implicated in the control of both hypoxia responses, HIF-1α and HIF-2α activation, as well as EMT induction. Intriguingly, different sirtuins have different effects on hypoxia and EMT, acting as either activators or inhibitors, depending on the tissue and cell type. Interestingly, sirtuins and HIF can be activated or inhibited with natural or synthetic molecules. Moreover, recent studies have shown that these natural or synthetic molecules can be better conveyed using nanoparticles, representing a valid strategy for EMT modulation. The following review, by detailing the aspects listed above, summarizes the interplay between hypoxia, sirtuins, and EMT, as well as the possible strategies to modulate them by using a nanoparticle-based approach.