Epithelial-mesenchymal transition transcription factors and miRNAs: “Plastic surgeons” of breast cancer

Navigating the therapeutic landscape for breast cancer: targeting breast cancer stem cells

Breast cancer is a common and deadly malignancy that affects women globally, and breast cancer stem cells (BCSCs) play an important role in tumorigenesis, development, metastasis, and recurrence. Traditional therapies often fail to eliminate BCSCs, leading to treatment resistance and relapse. This review explores the therapeutic strategies which are designed to target BCSCs, including inhibition of key signaling pathway and targeting receptor. This paper also explores the approaches to targeting BCSCs including chemotherapy, phytomedicines, and nanotechnology. Nanotechnology has gained a lot of importance in cancer therapy because of its ability to deliver therapeutic agents with more precision and minimal side effects. Various chemotherapeutic drugs, siRNAs, or gene editing tools are delivered efficiently with the use of nanocarriers which target pathways, receptors, and proteins associated with BCSCs. Over the past few years, stimuli-responsive and receptor-targeted nanocarriers have been explored for better therapeutic effects. In recent times, strategies such as chimeric antigen receptor (CAR) T-cell therapy, ablation therapy, and cell-free therapies are explored for targeting these stem cells. This review provides a recent developmental overview of strategies to attack BCSCs from conventional chemotherapeutic agents to nanotechnological platforms such as polymeric, lipidic, and metal-based nanoparticles and advanced technologies like CAR T cell therapies.

Targeted therapy approaches for epithelial-mesenchymal transition in triple negative breast cancer

Triple-negative breast cancer (TNBC) is distinguished by negative expression of estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2), making it an aggressive subtype of breast cancer and contributes to 15-20% of the total incidence. TNBC is a diverse disease with various genetic variations and molecular subtypes. The tumor microenvironment involves multiple cells, including immune cells, fibroblast cells, extracellular matrix (ECM), and blood vessels that constantly interact with tumor cells and influence each other. The ECM undergoes significant structural changes, leading to induced cell proliferation, migration, adhesion, invasion, and epithelial-to-mesenchymal transition (EMT). The involvement of EMT in the occurrence and development of tumors through invasion and metastasis in TNBC has been a matter of concern. Therefore, EMT markers could be prognostic predictors and potential therapeutic targets in TNBC. Chemotherapy has been one of the primary options for treating patients with TNBC, but its efficacy against TNBC is still limited. Targeted therapy is a critical emerging option with enhanced efficacy and less adverse effects on patients. Various targeted therapy approaches have been developed based on the specific molecules and the signaling pathways involved in TNBC. These include inhibitors of signaling pathways such as TGF-β, Wnt/β-catenin, Notch, TNF-α/NF-κB and EGFR, as well as immune checkpoint inhibitors, such as pembrolizumab, 2laparib, and talazoparib have been widely explored. This article reviews recent developments in EMT in TNBC invasion and metastasis and potential targeted therapy strategies.

MicroRNA-1205 promotes breast cancer cell metastasis by regulating epithelial-to-mesenchymal transition via targeting of CDK3

Metastasis poses a huge obstacle to the survival of breast cancer patients. The microRNA miR-1205 acts as a tumor suppressor in various cancers, but its roles in breast cancer and metastasis remain unclear. To elucidate its function in breast cancer progression, we analyzed miR-1205 expression in human tumor samples and carried out a series of functional studies in in vitro and in vivo. miR-1205 was expressed more highly in metastatic breast tumor samples than in non-metastatic samples and was associated with lymph node metastasis, clinical stage, and poor prognosis. Moreover, miR-1205 promoted breast cancer cell invasiveness in vitro and metastasis in mice by directly targeting CDK3 and reducing CDK3 protein levels. We also showed that CDK3 interacts with Snail protein, inducing Snail degradation via the ubiquitin-proteasome system and potentially affecting epithelial-to-mesenchymal transition. Furthermore, analysis of clinical tissue samples indicated that CDK3 and miR-1205 levels were inversely correlated in lymph node metastasis-positive primary tumors. This study demonstrated the pro-metastatic role of miR-1205 in breast cancer, mediated via a novel miR-1205/CDK3/Snail axis. Moreover, we identified miR-1205 and CDK3 as potential markers of invasion and progression in breast cancer.

Hypericum roeperianum bark extract suppresses breast cancer proliferation via induction of apoptosis, downregulation of PI3K/Akt/mTOR signaling cascade and reversal of EMT

ETHNOPHARMACOLOGICAL RELEVANCE

Hypericum roeperianum is a medicinal spice traditionally used in West Africa to treat female sterility, fungal infections, and cancer. It has previously been reported that H. roeperianum exhibits cytotoxic potential by reducing the viability of cancer cells involving multidrug-resistant phenotypes, but its underlying molecular mechanism remains unknown.

AIM OF THE STUDY

The mechanistic involvement of H. roeperianum methanolic crude extract (HRC) in attenuating breast cancer progression by exploring the effects on mitochondrial apoptosis and epithelial-mesenchymal transition (EMT) was investigated.

MATERIALS AND METHODS

In the present study, we examined the anticancer properties of HRC through MTT assay, colony formation, wound healing assay, spheroid formation, DNA fragmentation and flow cytometry for cell cycle arrest, apoptosis (Annexin V/PI staining) and mitochondrial membrane potential (MMP) (JC-1) detection. In addition, western blot analysis of various proteins and quantitative real time PCR of various genes involved in apoptosis, EMT and the PI3K/Akt/mToR signal transduction pathway were performed.

RESULTS

This study revealed that HRC treatment significantly decreased breast cancer cell viability, colony forming efficiency and reduced the ability of cell migration and spheroid formation. HRC also induced apoptosis in MDA-MB-231 and MCF-7 via promoting G0/G1 cell cycle arrest, disruption of mitochondrial membrane potential and induction of DNA damage. The crude extract induced apoptosis by activating the intrinsic pathway with a stronger effect that relies on the combined potency of associated molecular markers including Bax, Bad, Bcl-2, cytochrome C, caspase-9, and cleaved-PARP. It was also found that HRC regulates the PI3K/Akt/mToR pathway. In addition, HRC inhibited EMT by expressional alteration of Vimentin and E-cadherin, as well as the regulatory transcription factors such as Snail and Slug. The in vitro findings reflected similar mechanistic approach in 4T1 cell induced syngeneic mice model, indicating the reduction of tumor volume along with the significant expressional alteration of EMT and apoptotic markers.

CONCLUSION

Taken together the findings concluded that H. roeperianum is a potential source of cytotoxic phytochemicals that exhibit abortifacient effect on breast cancer, both in vitro and in vivo, thus could further be utilized in breast cancer therapy.

Cancer metastasis under the magnifying glass of epigenetics and epitranscriptomics

Most of the cancer-associated mortality and morbidity can be attributed to metastasis. The role of epigenetic and epitranscriptomic alterations in cancer origin and progression has been extensively demonstrated during the last years. Both regulations share similar mechanisms driven by DNA or RNA modifiers, namely writers, readers, and erasers; enzymes responsible of respectively introducing, recognizing, or removing the epigenetic or epitranscriptomic modifications. Epigenetic regulation is achieved by DNA methylation, histone modifications, non-coding RNAs, chromatin accessibility, and enhancer reprogramming. In parallel, regulation at RNA level, named epitranscriptomic, is driven by a wide diversity of chemical modifications in mostly all RNA molecules. These two-layer regulatory mechanisms are finely controlled in normal tissue, and dysregulations are associated with every hallmark of human cancer. In this review, we provide an overview of the current state of knowledge regarding epigenetic and epitranscriptomic alterations governing tumor metastasis, and compare pathways regulated at DNA or RNA levels to shed light on a possible epi-crosstalk in cancer metastasis. A deeper understanding on these mechanisms could have important clinical implications for the prevention of advanced malignancies and the management of the disseminated diseases. Additionally, as these epi-alterations can potentially be reversed by small molecules or inhibitors against epi-modifiers, novel therapeutic alternatives could be envisioned.

Clinical Relevancy of Circulating Tumor Cells in Breast Cancer: Epithelial or Mesenchymal Characteristics, Single Cells or Clusters?

Metastatic breast cancer (MBC) is typically an incurable disease with high mortality rates; thus, early identification of metastatic features and disease recurrence through precise biomarkers is crucial. Circulating tumor cells (CTCs) consisting of heterogeneous subpopulations with different morphology and genetic, epigenetic, and gene expression profiles represent promising candidate biomarkers for metastatic potential. The experimentally verified role of epithelial-to-mesenchymal transition in cancer dissemination has not been clearly described in BC patients, but the stemness features of CTCs strongly contributes to metastatic potency. Single CTCs have been shown to be protected in the bloodstream against recognition by the immune system through impaired interactions with T lymphocytes and NK cells, while associations of heterotypic CTC clusters with platelets, leucocytes, neutrophils, tumor-associated macrophages, and fibroblasts improve their tumorigenic behavior. In addition to single CTC and CTC cluster characteristics, we reviewed CTC evaluation methods and clinical studies in early and metastatic BCs. The variable CTC tests were developed based on specific principles and strategies. However, CTC count and the presence of CTC clusters were shown to be most clinically relevant in existing clinical trials. Despite the known progress in CTC research and sampling of BC patients, implementation of CTCs and CTC clusters in routine diagnostic and treatment strategies still requires improvement in detection sensitivity and precise molecular characterizations, focused predominantly on the role of CTC clusters for their higher metastatic potency.

The Role of ECM Remodeling, EMT, and Adhesion Molecules in Cancerous Neural Invasion: Changing Perspectives

Perineural invasion (PNI) refers to the cancerous invasion of nerves. It provides an alternative route for metastatic invasion and can exist independently in the absence of lymphatic or vascular invasion. It is a prominent characteristic of specific aggressive malignancies where it correlates with poor prognosis. The clinical significance of PNI is widely recognized despite a lack of understanding of the molecular mechanisms underlying its pathogenesis. The interaction between the nerve and the cancer cells is the most pivotal PNI step which is mediated by the activation or inhibition of multiple signaling pathways that include chemokines, interleukins, nerve growth factors, and matrix metalloproteinases, to name a few. The nerve-cancer cell interaction brings about specific changes in the perineural niche, which not only affects the regular nerve functions, but also enhances the migratory, invasive, and adherent properties of the tumor cells. This review aims to elucidate the vital role of adhesion molecules, extracellular matrix, and epithelial-mesenchymal proteins that promote PNI, which may serve as therapeutic targets in the future.

MicroRNA expression profiling of endocrine sensitive and resistant breast cancer cell lines

Background

Methods

Results

Conclusions

•

Around 50–60% of microRNAs were significantly differentially expressed between ER- and ER + breast cancer cell lines.

•

Transfection of miR-200c-3p mimic into ER -ve cells induced MET and reduced cell motility.

•

Transfecting of miR-449a inhibitor into ER -ve cells reduced cell invasion but did not induce EMT.

Heterogeneity and dynamic of EMT through the plasticity of ribosome and mRNA translation

Growing evidence exposes translation and its translational machinery as key players in establishing and maintaining physiological and pathological biological processes. Examining translation may not only provide new biological insight but also identify novel innovative therapeutic targets in several fields of biology, including that of epithelial-to-mesenchymal transition (EMT). EMT is currently considered as a dynamic and reversible transdifferentiation process sustaining the transition from an epithelial to mesenchymal phenotype, known to be mainly driven by transcriptional reprogramming. However, it seems that the characterization of EMT plasticity is challenging, relying exclusively on transcriptomic and epigenetic approaches. Indeed, heterogeneity in EMT programs was reported to depend on the biological context. Here, by reviewing the involvement of translational control, translational machinery and ribosome biogenesis characterizing the different types of EMT, from embryonic and adult physiological to pathological contexts, we discuss the added value of integrating translational control and its machinery to depict the heterogeneity and dynamics of EMT programs.

Epithelial-to-Mesenchymal Transition Signaling Pathways Responsible for Breast Cancer Metastasis

Breast carcinoma is highly metastatic and invasive. Tumor metastasis is a convoluted and multistep process involving tumor cell disseminating from their primary site and migrating to the secondary organ. Epithelial-mesenchymal transition (EMT) is one of the crucial steps that initiate cell progression, invasion, and metastasis. During EMT, epithelial cells alter their molecular features and acquire a mesenchymal phenotype. The regulation of EMT is centered by several signaling pathways, including primary mediators TGF-β, Notch, Wnt, TNF-α, Hedgehog, and RTKs. It is also affected by hypoxia and microRNAs (miRNAs). All these pathways are the convergence on the transcriptional factors such as Snail, Slug, Twist, and ZEB1/2. In addition, a line of evidence suggested that EMT and cancer stem like cells (CSCs) are associated. EMT associated cancer stem cells display mesenchymal phenotypes and resist to chemotherapy or targeted therapy. In this review, we highlighted recent discoveries in these signaling pathways and their regulation in breast cancer metastasis and invasion. While the clinical relevance of EMT and breast cancers remains controversial, we speculated a convergent signaling network pivotal to elucidating the transition of epithelial to mesenchymal phenotypes and onset of metastasis of breast cancer cells.

miR-205-5p Downregulation and ZEB1 Upregulation Characterize the Disseminated Tumor Cells in Patients with Invasive Ductal Breast Cancer

Background: Dissemination of breast cancer (BC) cells through the hematogenous or lymphogenous vessels leads to metastatic disease in one-third of BC patients. Therefore, we investigated the new prognostic features for invasion and metastasis. Methods: We evaluated the expression of miRNAs and epithelial-to-mesenchymal transition (EMT) genes in relation to CDH1/E-cadherin changes in samples from 31 patients with invasive ductal BC including tumor centrum (TU-C), tumor invasive front (TU-IF), lymph node metastasis (LNM), and CD45-depleted blood (CD45-DB). Expression of miRNA and mRNA was quantified by RT-PCR arrays and associations with clinico-pathological characteristics were statistically evaluated by univariate and multivariate analysis. Results: We did not verify CDH1 regulating associations previously described in cell lines. However, we did detect extremely high ZEB1 expression in LNMs from patients with distant metastasis, but without regulation by miR-205-5p. Considering the ZEB1 functions, this overexpression indicates enhancement of metastatic potential of lymphogenously disseminated BC cells. In CD45-DB samples, downregulated miR-205-5p was found in those expressing epithelial and/or mesenchymal markers (CTC+) that could contribute to insusceptibility and survival of hematogenously disseminated BC cells mediated by increased expression of several targets including ZEB1. Conclusions: miR-205-5p and potentially ZEB1 gene are promising candidates for markers of metastatic potential in ductal BC.

Epigenetic Reprogramming and Landscape of Transcriptomic Interactions: Impending Therapeutic Interference of Triple-Negative Breast Cancer in Molecular Medicine

The mechanisms governing the development and progression of cancers are believed to be the consequence of hereditary deformities and epigenetic modifications. Accordingly, epigenetics has become an incredible and progressively explored field of research to discover better prevention and therapy for neoplasia, especially triple-negative breast cancer (TNBC). It represents 15-20% of all invasive breast cancers and will, in general, have bellicose histological highlights and poor clinical outcomes. In the early phases of triple-negative breast carcinogenesis, epigenetic deregulation modifies chromatin structure and influences the plasticity of cells. It up-keeps the oncogenic reprogramming of malignant progenitor cells with the acquisition of unrestrained selfrenewal capacities. Genomic impulsiveness in TNBC prompts mutations, copy number variations, as well as genetic rearrangements, while epigenetic remodeling includes an amendment by DNA methylation, histone modification, and noncoding RNAs of gene expression profiles. It is currently evident that epigenetic mechanisms assume a significant part in the pathogenesis, maintenance, and therapeutic resistance of TNBC. Although TNBC is a heterogeneous malaise that is perplexing to describe and treat, the ongoing explosion of genetic and epigenetic research will help to expand these endeavors. Latest developments in transcriptome analysis have reformed our understanding of human diseases, including TNBC at the molecular medicine level. It is appealing to envision transcriptomic biomarkers to comprehend tumor behavior more readily regarding its cellular microenvironment. Understanding these essential biomarkers and molecular changes will propel our capability to treat TNBC adequately. This review will depict the different aspects of epigenetics and the landscape of transcriptomics in triple-negative breast carcinogenesis and their impending application for diagnosis, prognosis, and treatment decision with the view of molecular medicine.

Progesterone receptor antagonists reverse stem cell expansion and the paracrine effectors of progesterone action in the mouse mammary gland

Background

The ovarian hormones estrogen and progesterone (EP) are implicated in breast cancer causation. A specific consequence of progesterone exposure is the expansion of the mammary stem cell (MSC) and luminal progenitor (LP) compartments. We hypothesized that this effect, and its molecular facilitators, could be abrogated by progesterone receptor (PR) antagonists administered in a mouse model.

Methods

Ovariectomized FVB mice were randomized to 14 days of treatment: sham, EP, EP + telapristone (EP + TPA), EP + mifepristone (EP + MFP). Mice were then sacrificed, mammary glands harvested, and mammary epithelial cell lineages separated by flow cytometry using cell surface markers. RNA from each lineage was sequenced and differential gene expression was analyzed using DESeq. Quantitative PCR was performed to confirm the candidate genes discovered in RNA seq. ANOVA with Tukey post hoc analysis was performed to compare relative expression. Alternative splicing events were examined using the rMATs multivariate analysis tool.

Results

Significant increases in the MSC and luminal mature (LM) cell fractions were observed following EP treatment compared to control (p < 0.01 and p < 0.05, respectively), whereas the LP fraction was significantly reduced (p < 0.05). These hormone-induced effects were reversed upon exposure to TPA and MFP (p < 0.01 for both). Gene Ontology analysis of RNA-sequencing data showed EP-induced enrichment of several pathways, with the largest effect on Wnt signaling in MSC, significantly repressed by PR inhibitors. In LP cells, significant induction of Wnt4 and Rankl, and Wnt pathway intermediates Lrp2 and Axin2 (confirmed by qRTPCR) were reversed by TPA and MFP (p < 0.0001). Downstream signaling intermediates of these pathways (Lrp5, Mmp7) showed similar effects. Expression of markers of epithelial-mesenchymal transition (Cdh1, Cdh3) and the induction of EMT regulators (Zeb1, Zeb2, Gli3, Snai1, and Ptch2) were significantly responsive to progesterone. EP treatment was associated with large-scale alternative splicing events, with an enrichment of motifs associated with Srsf, Esrp, and Rbfox families. Exon skipping was observed in Cdh1, Enah, and Brd4.

Conclusions

PR inhibition reverses known tumorigenic pathways in the mammary gland and suppresses a previously unknown effect of progesterone on RNA splicing events. In total, our results strengthen the case for reconsideration of PR inhibitors for breast cancer prevention.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13058-021-01455-2.

Upregulation of miR-206 is a potential diagnostic biomarker in breast cancer

Breast cancer is one of the most common malignancies, and like most cancers, most cases are caused by somatic mutations. Due to estrogen's role in the growth, differentiation, and division of breast and endometrial cancer cells, tamoxifen is used as an estrogen receptor antagonist in breast cancer cells with estrogen receptor (ER +) has a special place, which unfortunately in one-third of the Cases are resisted. This study aimed to investigate the effect of tamoxifen-treated tumor-derived exosomes on the expression pattern of Twist and Bcl-2 oncogenic genes in fibroblast cells. MCF-7 breast cancer cell line and fibroblast cells were purchased and cultured in a complete culture medium. After the appropriate number of cells was reached, they were treated with the appropriate concentration of tamoxifen. Cellular supernatant was then gathered in flasks, and exosomes were extracted from them. After extracting RNA from exosomes and cDNA synthesis, the expression level of miR-206, Twist-1, and Bcl-2 genes were evaluated using the Real-Time PCR method. The electronic microscope results confirmed the correctness of the exosomes isolated from the tumor cell culture medium. It has also been shown that tamoxifen treatment increases the expression of miR-206 in exosomes derived from breast tumor cells. The control group which has been kept untreated induced the expression level of Twist-1 and Bcl-2 genes time-dependently. However, when tamoxifen-treated tumor-derived exosomes treated the target cells, the expression level of oncogenic miRs Twist-1 and Bcl-2 were declined over time. Overall, this study showed that tamoxifen treatment on breast cancer cells could apply its antioncogenic effects on tumor stromal cells, such as fibroblasts, by altering the expression levels of exosomal microRNAs in tumor cells.

Determining Factors in the Therapeutic Success of Checkpoint Immunotherapies against PD-L1 in Breast Cancer: A Focus on Epithelial-Mesenchymal Transition Activation

Breast cancer is the most common neoplasm diagnosed in women around the world. Checkpoint inhibitors, targeting the programmed death receptor-1 or ligand-1 (PD-1/PD-L1) axis, have dramatically changed the outcome of cancer treatment. These therapies have been recently considered as alternatives for treatment of breast cancers, in particular those with the triple-negative phenotype (TNBC). A further understanding of the regulatory mechanisms of PD-L1 expression is required to increase the benefit of PD-L1/PD-1 checkpoint immunotherapy in breast cancer patients. In this review, we will compile the most recent studies evaluating PD-1/PD-L1 checkpoint inhibitors in breast cancer. We review factors that determine the therapeutic success of PD-1/PD-L1 immunotherapies in this pathology. In particular, we focus on pathways that interconnect the epithelial-mesenchymal transition (EMT) with regulation of PD-L1 expression. We also discuss the relationship between cellular metabolic pathways and PD-L1 expression that are involved in the promotion of resistance in TNBC.

Anti-tumor effects of Artemisia nilagirica extract on MDA-MB-231 breast cancer cells: deciphering the biochemical and biomechanical properties via TGF-β upregulation

Purpose

Artemisia nilagirica (AN), which is known to have antimicrobial, antioxidant, antiulcer, and anti-asthmatic properties, has been recently shown to have anti-cancer activity. However, the mechanism responsible for the anti-cancer property and its effect on cellular properties and functions are not known.

Material and methods

We have characterized the biochemical and biomechanical properties of MDA-MB-231 cells treated with the methanolic extract from AN.

Results

We show that AN-treatment decreases cell-eccentricity, increases expression of actin and microtubules, and do not affect cell-area. Increased expression of cytoskeletal proteins is known to change the mechanical properties of the cells, which was confirmed using micropipette aspiration and Atomic Force Microscopy. We identified the upregulation of the tumorigenic pathway (TGF-β) leading to activation of Rho-A as the molecular mechanism responsible for actin upregulation. Since the initial stages of TGF-β upregulation are known to suppress tumor growth by activating apoptosis, we hypothesized that the mechanism of cell death due to AN-treatment is through TGF-β activation. We have validated this hypothesis by partially recuing cell death through inhibition of TGF-β using Alk-5.

Conclusion

In summary, our study reveals the mechanism of action of Artemisia nilagirica using a synergy between biochemical and biomechanical techniques.

MicroRNAs target the Wnt/β‑catenin signaling pathway to regulate epithelial‑mesenchymal transition in cancer (Review)

Epithelial‑mesenchymal transition (EMT), during which cancer cells lose the epithelial phenotype and gain the mesenchymal phenotype, has been verified to result in tumor migration and invasion. Numerous studies have shown that dysregulation of the Wnt/β‑catenin signaling pathway gives rise to EMT, which is characterized by nuclear translocation of β‑catenin and E‑cadherin suppression. Wnt/β‑catenin signaling was confirmed to be affected by microRNAs (miRNAs), several of which are down‑ or upregulated in metastatic cancer cells, indicating their complex roles in Wnt/β‑catenin signaling. In this review, we demonstrated the targets of various miRNAs in altering Wnt/β‑catenin signaling to promote or inhibit EMT, which may elucidate the underlying mechanism of EMT regulation by miRNAs and provide evidence for potential therapeutic targets in the treatment of invasive tumors.

Fusobacterium nucleatum produces cancer stem cell characteristics via EMT-resembling variations

OBJECTIVE

To explore the involvement of epithelial-mesenchymal transition (EMT) and cancer stem cell (CSC) characteristics induced by Fusobacterium nucleatum (Fn) in colorectal cancer (CRC) in vitro.

METHODS

SW480 and HCT116 cells were co-cultivated with Fn. Western blot (WB) and real-time PCR were used for detecting EMT markers' expression. CSC-resembling phenotypes were observed through migration, intrusion, and spherical colony formation assays. Flow cytometry was employed for sorting, based on the expression of CD44.

RESULTS

It was displayed that Fn infection was responsible for an EMT phenotype associated with an increase in mesenchymal markers (Snail1, Vimentin, and ZEB1) as well as CD44 expression. Fn treatment induced stronger expressions of such markers when MOI increased. Furthermore, infection resulted in augmented migration, intrusion, and tumorsphere formation capacities. Cell classification implicated that mere CD44^high cells exhibited CSC characteristics and mesenchymal phenotype (MP) in vitro, accompanied with augmented tumor-causing capacity over CD44^low cells. Finally, we demonstrated IL-6/STAT3 pathway was involved in EMT-CSC-resembling behavior of CRC cells.

CONCLUSION

All of these data suggest that Fn reveals CSC-resembling characteristics through activating IL-6/STAT3 and eliciting EMT-resembling variations in colorectal epithelial cells (CECs).

The A818-6 system as an in-vitro model for studying the role of the transportome in pancreatic cancer

Background

The human pancreatic cancer cell line A818–6 can be grown in vitro either as a highly malignant, undifferentiated monolayer (ML) or as three-dimensional (3D) single layer hollow spheres (HS) simulating a benign, highly differentiated, duct-like pancreatic epithelial structure. This characteristic allowing A818–6 cells to switch from one phenotype to another makes these cells a unique system to characterize the cellular and molecular modifications during differentiation on one hand and malignant transformation on the other hand. Ion channels and transport proteins (transportome) have been implicated in malignant transformation. Therefore, the current study aimed to analyse the transportome gene expression profile in the A818–6 cells growing as a monolayer or as hollow spheres.

Methods & Results

The study identified the differentially expressed transportome genes in both cellular states of A818–6 using Agilent and Nanostring arrays and some targets were validated via immunoblotting. Additionally, these results were compared to a tissue Affymetrix microarray analysis of pancreatic adenocarcinoma patients’ tissues. The overall transcriptional profile of the ML and HS cells confirmed the formerly described mesenchymal features of ML and epithelial nature of HS which was further verified via high expression of E-cadherin and low expression of vimentin found in HS in comparison to ML. Among the predicted features between HS and ML was the involvement of miRNA-9 in this switch. Importantly, the bioinformatics analysis also revealed substantial number (n = 126) of altered transportome genes. Interestingly, three genes upregulated in PDAC tissue samples (GJB2, GJB5 and SLC38A6) were found to be also upregulated in ML and 3 down-regulated transportome genes (KCNQ1, TRPV6 and SLC4A) were also reduced in ML.

Conclusion

This reversible HS/ML in vitro system might help in understanding the pathophysiological impact of the transportome in the dedifferentiation process in pancreatic carcinogenesis. Furthermore, the HS/ML model represents a novel system for studying the role of the transportome during the switch from a more benign, differentiated (HS) to a highly malignant, undifferentiated (ML) phenotype.

Recent Advances in Microfluidic Platforms Applied in Cancer Metastasis: Circulating Tumor Cells' (CTCs) Isolation and Tumor-On-A-Chip

Cancer remains the leading cause of death worldwide despite the enormous efforts that are made in the development of cancer biology and anticancer therapeutic treatment. Furthermore, recent studies in oncology have focused on the complex cancer metastatic process as metastatic disease contributes to more than 90% of tumor-related death. In the metastatic process, isolation and analysis of circulating tumor cells (CTCs) play a vital role in diagnosis and prognosis of cancer patients at an early stage. To obtain relevant information on cancer metastasis and progression from CTCs, reliable approaches are required for CTC detection and isolation. Additionally, experimental platforms mimicking the tumor microenvironment in vitro give a better understanding of the metastatic microenvironment and antimetastatic drugs' screening. With the advancement of microfabrication and rapid prototyping, microfluidic techniques are now increasingly being exploited to study cancer metastasis as they allow precise control of fluids in small volume and rapid sample processing at relatively low cost and with high sensitivity. Recent advancements in microfluidic platforms utilized in various methods for CTCs' isolation and tumor models recapitulating the metastatic microenvironment (tumor-on-a-chip) are comprehensively reviewed. Future perspectives on microfluidics for cancer metastasis are proposed.

MicroRNAs Contribute to Breast Cancer Invasiveness

Cancer statistics in 2018 highlight an 8.6 million incidence in female cancers, and 4.2 million cancer deaths globally. Moreover, breast cancer is the most frequent malignancy in females and twenty percent of these develop metastasis. This provides only a small chance for successful therapy, and identification of new molecular markers for the diagnosis and prognostic prediction of metastatic disease and development of innovative therapeutic molecules are therefore urgently required. Differentially expressed microRNAs (miRNAs) in cancers cause multiple changes in the expression of the tumorigenesis-promoting genes which have mostly been investigated in breast cancers. Herein, we summarize recent data on breast cancer-specific miRNA expression profiles and their participation in regulating invasive processes, in association with changes in cytoskeletal structure, cell-cell adhesion junctions, cancer cell-extracellular matrix interactions, tumor microenvironments, epithelial-to-mesenchymal transitions and cancer cell stem abilities. We then focused on the epigenetic regulation of individual miRNAs and their modified interactions with other regulatory genes, and reviewed the function of miRNA isoforms and exosome-mediated miRNA transfer in cancer invasiveness. Although research into miRNA’s function in cancer is still ongoing, results herein contribute to improved metastatic cancer management.

P53-R273H mutation enhances colorectal cancer stemness through regulating specific lncRNAs

Background

TP53 is one of the most frequently mutated genes among all cancer types, and TP53 mutants occur more than 60% in colorectal cancer (CRC). Among all mutants, there are three hot spots, including p53-R175H, p53-R248W and p53-R273H. Emerging evidence attributes cancer carcinogenesis to cancer stem cells (CSCs). Long noncoding RNAs (lncRNAs) play crucial roles in maintaining the stemness of CSCs. However, it is unknown if mutant p53-regulated lncRNAs are implicated in the maintenance of CSC stemness.

Methods

RNA-sequencing (RNA-seq) and ChIP-sequencing (ChIP-seq) were used to trace the lncRNA network regulated by p53-R273H in HCT116 endogenous p53 point mutant spheroid cells generated by the somatic cell knock-in method. RT-qPCR was used to detect lncRNA expression patterns, verifying the bioinformatics analysis. Transwell, spheroid formation, fluorescence activated cell sorter (FACS), xenograft nude mouse model, tumor frequency assessed by extreme limiting dilution analysis (ELDA), Western blot assays and chemoresistance analysis were performed to elucidate the functions and possible mechanism of lnc273–31 and lnc273–34 in cancer stem cells.

Results

p53-R273H exhibited more characteristics of CSC than p53-R175H and p53-R248W. RNA-seq profiling identified 37 up regulated and 4 down regulated differentially expressed lncRNAs regulated by p53-R273H. Combined with ChIP-seq profiling, we further verified two lncRNAs, named as lnc273–31 and lnc273–34, were essential in the maintenance of CSC stemness. Further investigation illustrated that lnc273–31 or lnc273–34 depletion dramatically diminished colorectal cancer migration, invasion, cancer stem cell self-renewal and chemoresistance in vitro. Moreover, the absence of lnc273–31 or lnc273–34 dramatically delayed cancer initiation and tumorigenic cell frequency in vivo. Also, lnc273–31 and lnc273–34 have an impact on epithelial-to mesenchymal transition (EMT). Finally, lnc273–31 and lnc273–34 were significantly highly expressed in CRC tissues with p53-R273H mutation compared to those with wildtype p53.

Conclusions

The present study unveiled a high-confidence set of lncRNAs regulated by p53-R273H specific in colorectal CSCs. Furthermore, we demonstrated that two of them, lnc273–31 and lnc273–34, were required for colorectal CSC self-renewal, tumor propagation and chemoresistance. Also, the expression of these two lncRNAs augmented in colorectal cancer patient samples with p53-R273H mutation. These two lncRNAs may serve as promising predictors for patients with p53-R273H mutation and are vital for chemotherapy.

Electronic supplementary material

The online version of this article (10.1186/s13046-019-1375-9) contains supplementary material, which is available to authorized users.

miR-23b-3p and miR-130a-5p affect cell growth, migration and invasion by targeting CB1R via the Wnt/β-catenin signaling pathway in gastric carcinoma

Background

Gastric cancer (GC) is the most common malignancy and third leading cause of cancer mortality worldwide. The identification of a sensitive biomarker as well as effective therapeutic targets for the treatment of GC is of critical importance. microRNAs play significant roles in the development of cancer and may serve as promising therapeutic targets.

Methods

The mRNA and protein expression of CB1R were studied both in GC cells and tissues. GC cell lines with specific gene overexpression and knockdown vectors were constructed. CCK-8 assay, matrigel invasion and colony formation assays were performed to evaluate the proliferation and invasion abilities. The binding and regulatory effects of miR-23b-3 and miR-130a-5p on CB1R mRNA were investigated using a luciferase reporter assay. Western blot analysis was performed to explore the potential interaction proteins of CB1R.

Results

In the present study, it was demonstrated that the cannabinoid receptor 1 (CB1R) was overexpressed, and miR-23b-3p and miR-130a-5p were downregulated, in GC cells. In addition, the results revealed that these effects are associated with malignant biological behaviors exhibited by GC cells. Furthermore, miR-23b-3p and miR-130a-5p may regulate CB1R expression via the Wnt/β-catenin signaling pathway.

Conclusion

Our results suggested dysregulation of CB1R expression is closely related to the malignant biological behavior of gastric cancer cells. miRNA/CB1R-based therapy may represent a promising therapeutic strategy for the clinical treatment of GC patients.

Fisetin Inhibited Growth and Metastasis of Triple-Negative Breast Cancer by Reversing Epithelial-to-Mesenchymal Transition via PTEN/Akt/GSK3β Signal Pathway

Triple negative breast cancer (TNBC), characterized by its highly aggressive and metastatic features, is associated with poor prognosis and high mortality partly due to lack of effective treatment. Fisetin, a natural flavonoid compound, has been demonstrated to possess anti-cancer effects in various cancers. However, the effects and mechanisms of fisetin on metastasis of TNBC remain uncovered. In this study, we found that fisetin dose-dependently inhibited cell proliferation, migration and invasion in TNBC cell lines MDA-MB-231 and BT549 cells. In addition, fisetin reversed epithelial to mesenchymal transition (EMT) as evaluated by cell morphology and EMT markers in MDA-MB-231 and BT549 cells. Furthermore, fisetin suppressed phosphoinositol 3-kinase (PI3K)-Akt-GSK-3β signaling pathway but upregulated the expression of PTEN mRNA and protein in a concentration-dependent manner. Further, silence of PTEN by siRNA abolished these benefits of fisetin on proliferation and metastasis of TNBCs. In vivo, using the metastatic breast cancer xenograft model bearing MDA-MB-231 cells, we found that fisetin dramatically inhibited growth of primary breast tumor and reduced lung metastasis, meanwhile, the expression of EMT molecules and PTEN/Akt/GSK-3β in primary and metastatic tissues changed in the same way as those in vitro experiments. In conclusion, all these results indicated that fisetin could effectively suppress proliferation and metastasis of TNBC and reverse EMT process, which might be mediated by PTEN/Akt/GSK-3β signaling pathway.

Epithelial mesenchymal transition Transcription Factor (TF): The structure, function and microRNA feedback loop

Epithelial to mesenchymal transition (EMT) is a phenomenon in which epithelial cells lose their cell to cell adhesion and detach from the base of the membrane. EMT is a fundamental process which occurs during tumor progression and metastasis. Cancer genomics is a complex network which involves a variety of factors such as transcription factors (TFs), coding genes and microRNAs (miRs). Both TFs and miRs are trans-regulatory elements that crosstalk. Due to a wide range of targets, TF-miR interaction provides a feedback or feedforward loop and cross-gene regulation consequently. In this review, we focused on the structure and function of two TF families involved in EMT, zinc finger and β helix loop helix and p53. Subsequently we analyzed recent findings on TF-miR interaction in EMT.

Targeting epithelial-mesenchymal plasticity in cancer: clinical and preclinical advances in therapy and monitoring

The concept of epithelial-mesenchymal plasticity (EMP), which describes the dynamic flux within the spectrum of phenotypic states that invasive carcinoma cells may reside, is being increasingly recognised for its role in cancer progression and therapy resistance. The myriad of events that are able to induce EMP, as well as the more recently characterised control loops, results in dynamic transitions of cancerous epithelial cells to more mesenchymal-like phenotypes through an epithelial-mesenchymal transition (EMT), as well as the reverse transition from mesenchymal phenotypes to an epithelial one. The significance of EMP, in its ability to drive local invasion, generate cancer stem cells and facilitate metastasis by the dissemination of circulating tumour cells (CTCs), highlights its importance as a targetable programme to combat cancer morbidity and mortality. The focus of this review is to consolidate the existing knowledge on the strategies currently in development to combat cancer progression via inhibition of specific facets of EMP. The prevalence of relapse due to therapy resistance and metastatic propensity that EMP endows should be considered when designing therapy regimes, and such therapies should synergise with existing chemotherapeutics to benefit efficacy. To further improve upon EMP-targeted therapies, it is imperative to devise monitoring strategies to assess the impact of such treatments on EMP-related phenomenon such as CTC burden, chemosensitivity/-resistance and micrometastasis in patients.

Epithelial, mesenchymal and hybrid epithelial/mesenchymal phenotypes and their clinical relevance in cancer metastasis

Cancer metastasis occurs through local invasion of circulating tumour cells (CTCs), intravasation, transportation to distant sites, and their extravasation followed by colonisation at secondary sites. Epithelial-mesenchymal transition (EMT) is a normal developmental phenomenon, but its aberrant activation confers tumour cells with enhanced cell motility, metastatic properties, resistant to therapies and cancer stem cell (CSC) phenotype in epithelium-derived carcinoma. Experimental studies from various research papers have been reviewed to determine the factors, which interlink cancer stemness and cellular plasticity with EMT. Although existence of CSCs has been linked with EMT, nevertheless, there are controversies with the involvement of type of tumour cells, including cells with E (epithelial) and M (mesenchymal) phenotype alone or hybrid E/M phenotype in different types of cancers. Studies on CTCs with hybrid E/M phenotypes during different stages of cancer metastasis reveal strong association with tumour -initiation potential, cellular plasticity and types of cancer cells. Cells with the hybrid E/M state are strictly controlled by phenotypic stability factors coupled to core EMT decision-making circuits, miR200/ZEB and miR-34/Snail. Understanding the regulatory functions of EMT program in cancer metastasis can help us to characterise the biomarkers of prognostic and therapeutic potential. These biomarkers when targeted may act as metastatic suppressors, inhibit cellular plasticity and stemness ability of tumour cells and can block metastatic growth.

Downregulation of microRNA-145 promotes epithelial-mesenchymal transition via regulating Snail in osteosarcoma

Metastasis is the principal cause of cancer death and occurs through multiple, complex processes. Epithelial to mesenchymal transition (EMT) is an important process during embryonic development and has also been hypothesized to exhibit a significant role in cancer cell invasion and metastasis. MicroRNAs (miRNAs) are a class of widespread noncoding RNAs. In recent years, many studies have shown that miRNAs could influence the signaling pathways and downstream events that define EMT on a molecular level. However, the exact role and mechanisms of miR-145 in EMT of osteosarcoma (OS) was unknown. In the present study, miR-145 was downregulated in OS tissues and cell lines and it was shown that miR-145 expression was closely correlated with advanced tumor progression in patients of OS. In addition, miR-145 upregulation by miR-145 agomir significantly inhibited MG63 cells invasion and migration ability. MiR-145 was reported to be able to inhibit EMT in cancers. Following the examination of changes in cell epithelial and mesenchymal markers, it was found that upregulation of miR-145 strongly reversed EMT in MG63 cells. Meanwhile, the expression of Snail, a strong E-cadherin transcription repressor was also attenuated by miR-145 agomir. Furthermore, the decreased EMT and invasion and metastasis caused by miR-145 agomir could be restored by Snail siRNA. In conclusion, the results demonstrated that miR-145 could mediate EMT by targeting Snail and miR-145 might be a novel EMT regulating transcription factor that involved in the progression of OS. The specific drugs targeting miR-145-mediated EMT process might be new promising cancer therapies.

Epithelial-mesenchymal transition in cholangiocarcinoma: From clinical evidence to regulatory networks

Cholangiocarcinoma (CCA) is an aggressive tumor with a poor prognosis due to its late clinical presentation and the lack of effective non-surgical therapies. Unfortunately, most of the patients are not eligible for curative surgery owing to the presence of metastases at the time of diagnosis. Therefore, it is important to understand the steps leading to cell dissemination in patients with CCA. To metastasize from the primary site, cancer cells must acquire migratory and invasive properties by a cell plasticity-promoting phenomenon known as epithelial-mesenchymal transition (EMT). EMT is a reversible dynamic process by which epithelial cells gradually adopt structural and functional characteristics of mesenchymal cells, and has lately become a centre of attention in the field of metastatic dissemination. In the present review, we aim to provide an extensive overview of the current clinical data and the prognostic value of different EMT markers that have been analysed in CCA. We summarize all the regulatory networks implicated in EMT from the membrane receptors to the main EMT-inducing transcription factors (SNAIL, TWIST and ZEB). Furthermore, since a tumor is a complex structure not exclusively formed by tumor cells, we also address the prominent role of the main cell types of the desmoplastic stroma that characterizes CCA in the regulation of EMT. Finally, we discuss the therapeutic considerations and difficulties faced to develop an effective anti-EMT treatment due to the redundancies and bypasses among the pathways regulating EMT.

Epithelial Plasticity During Human Breast Morphogenesis and Cancer Progression

Understanding the complex events leading to formation of an epithelial-based organ such as the breast requires a detailed insight into the crosstalk between epithelial and stromal compartments. These interactions occur both through heterotypic cellular interactions and between cells and matrix components. While in vivo models may partially capture these complex interactions, there is a need for in- vitro models to study these events. In this review we discuss cell-cell interactions in breast development focusing on the stem cell niche and branching morphogenesis. Given the recent understanding that the basic developmental events underlying branching morphogenesis are closely related to pathways important to cancer progression, i.e. epithelial plasticity and epithelial to mesenchymal transition (EMT), we will also discuss aspects relevant to cancer progression. In cancer, the adoption of mesenchymal phenotype by the malignant cells allows stromal invasion and subsequent intravasation to blood- or lymphatic vessels, a route that is a prerequisite for metastasis. A number of publications have demonstrated that tumor initiating cells, sometimes referred to as cancer stem cells adapt an EMT phenotype that renders them more resistant to apoptosis and drug therapy. The mechanism behind this phenomenon is currently unknown but this may partially explain relapse in breast cancer patients. Increased understanding of branching morphogenesis in the breast gland and the regulation of EMT and its reverse process mesenchymal to epithelial transition (MET) may hold the keys for future development of methods/drugs that neutralize the invading properties of cancer cells.

Biomarkers for EMT and MET in breast cancer: An update

Metastasis and recurrence are the leading cause of mortality due to breast cancer, but the underlying mechanisms are still poorly understood. Understanding the breast cancer metastasis mechanism is important for early diagnosis and treatment of breast cancer. The seeding and growth of breast cancer cells at sites distinct from the primary tumor is a complex and multistage process. Recently, it has been reported that the epithelial-mesenchymal transition (EMT) and the mesenchymal-epithelial transition (MET) are the main mechanisms for breast cancer metastasis. During EMT, carcinoma cells shed their differentiated epithelial characteristics, including cell-cell adhesion, polarity and lack of motility, and acquire mesenchymal traits, including motility and invasiveness. This review has summarized the studies of known EMT biomarkers in the context of breast cancer progression. These biomarkers include EMT-related genes, proteins, microRNAs and kinases. In general, the findings of these studies suggest that EMT markers are associated with the invasion and metastasis of breast cancer. Further studies on the link between EMT markers and breast cancer will contribute to identify biomarkers for predicting early breast cancer metastasis as well as to provide new ideas for the treatment of breast cancer.

Tackling Cancer Stem Cells via Inhibition of EMT Transcription Factors

Cancer stem cell (CSC) has become recognized for its role in both tumorigenesis and poor patient prognosis in recent years. Traditional therapeutics are unable to effectively eliminate this group of cells from the bulk population of cancer cells, allowing CSCs to persist posttreatment and thus propagate into secondary tumors. The therapeutic potential of eliminating CSCs, to decrease tumor relapse, has created a demand for identifying mechanisms that directly target and eliminate cancer stem cells. Molecular profiling has shown that cancer cells and tumors that exhibit the CSC phenotype also express genes associated with the epithelial-to-mesenchymal transition (EMT) feature. Ample evidence has demonstrated that upregulation of master transcription factors (TFs) accounting for the EMT process such as Snail/Slug and Twist can reprogram cancer cells from differentiated to stem-like status. Despite being appealing therapeutic targets for tackling CSCs, pharmacological approaches that directly target EMT-TFs remain impossible. In this review, we will summarize recent advances in the regulation of Snail/Slug and Twist at transcriptional, translational, and posttranslational levels and discuss the clinical implication and application for EMT blockade as a promising strategy for CSC targeting.

Microengineered cancer-on-a-chip platforms to study the metastatic microenvironment

More than 90% of cancer-related deaths can be attributed to the occurrence of metastatic diseases. Recent studies have highlighted the importance of the multicellular, biochemical and biophysical stimuli from the tumor microenvironment during carcinogenesis, treatment failure, and metastasis. Therefore, there is a need for experimental platforms that are able to recapitulate the complex pathophysiological features of the metastatic microenvironment. Recent advancements in biomaterials, microfluidics, and tissue engineering have led to the development of living multicellular microculture systems, which are maintained in controllable microenvironments and function with organ level complexity. The applications of these "on-chip" technologies for detection, separation, characterization and three dimensional (3D) propagation of cancer cells have been extensively reviewed in previous works. In this contribution, we focus on integrative microengineered platforms that allow the study of multiple aspects of the metastatic microenvironment, including the physicochemical cues from the tumor associated stroma, the heterocellular interactions that drive trans-endothelial migration and angiogenesis, the environmental stresses that metastatic cancer cells encounter during migration, and the physicochemical gradients that direct cell motility and invasion. We discuss the application of these systems as in vitro assays to elucidate fundamental mechanisms of cancer metastasis, as well as their use as human relevant platforms for drug screening in biomimetic microenvironments. We then conclude with our commentaries on current progress and future perspectives of microengineered systems for fundamental and translational cancer research.

[Cancer cell plasticity and metastatic dissemination]

Metastatic dissemination consists of a sequence of events resulting in the invasion by cancer cells of tissues located away from the primary tumour. This process is highly inefficient, since each event represents an obstacle that only a limited number of cells can overcome. However, two biological phenomena intrinsically linked with tumour development facilitate the dissemination of cancer cells throughout the body and promote the formation of metastases, namely the genetic diversity of cancer cells within a given tumour, which arises from their genetic instability and from successive clonal expansions, and cellular plasticity conveyed to the cells by micro-environmental signals. Genetic diversity increases the probability of selecting cells that are intrinsically resistant to biological and physical constraints encountered during metastatic dissemination, whereas cellular plasticity provides cells with the capacity to adapt to stressful conditions and to changes in the microenvironment. The epithelial-mesenchymal transition, an embryonic trans-differentiation process frequently reactivated during tumour development, plays an important role in that context by endowing tumor cells with a unique capacity of motility, survival and adaptability to the novel environments and stresses encountered during the invasion-metastasis cascade.

Interaction between Wnt/β-catenin pathway and microRNAs regulates epithelial-mesenchymal transition in gastric cancer (Review)

Gastric cancer (GC) is the third primary cause of cancer-related mortality and one of the most common type of malignant diseases worldwide. Despite remarkable progress in multimodality therapy, advanced GC with high aggressiveness always ends in treatment failure. Epithelial-mesenchymal transition (EMT) has been widely recognized to be a key process associating with GC evolution, during which cancer cells go through phenotypic variations and acquire the capability of migration and invasion. Wnt/β-catenin pathway has established itself as an EMT regulative signaling due to its maintenance of epithelial integrity as well as tight adherens junctions while mutations of its components will lead to GC initiation and diffusion. The E-cadherin/β-catenin complex plays an important role in stabilizing β-catenin at cell membrane while disruption of this compound gives rise to nuclear translocation of β-catenin, which accounts for upregulation of EMT biomarkers and unfavorable prognosis. Additionally, several microRNAs positively or negatively modify EMT by reciprocally acting with certain target genes of Wnt/β-catenin pathway in GC. Thus, this review centers on the strong associations between Wnt/β-catenin pathway and microRNAs during alteration of EMT in GC, which may induce advantageous therapeutic strategies for human gastric cancer.

Let-7d miRNA Shows Both Antioncogenic and Oncogenic Functions in Osteosarcoma-Derived 3AB-OS Cancer Stem Cells

Osteosarcoma (OS), an aggressive highly invasive and metastatic bone-malignancy, shows therapy resistance and recurrence, two features that likely depend on cancer stem cells (CSCs), which hold both self-renewing and malignant potential. So, effective anticancer therapies against OS should specifically target and destroy CSCs. We previously found that the let-7d microRNA was downregulated in the 3AB-OS-CSCs, derived from the human OS-MG63 cells. Here, we aimed to assess whether let-7d modulation affected tumorigenic and stemness properties of these OS-CSCs. We found that let-7d-overexpression reduced cell proliferation by decreasing CCND2 and E2F2 cell-cycle-activators and increasing p21 and p27 CDK-inhibitors. Let-7d also decreased sarcosphere-and-colony forming ability, two features associated with self-renewing, and it reduced the expression of stemness genes, including Oct3/4, Sox2, Nanog, Lin28B, and HMGA2. Moreover, let-7d induced mesenchymal-to-epithelial-transition, as shown by both N-Cadherin-E-cadherin-switch and decrease in vimentin. Surprisingly, such switch was accompanied by enhanced migratory/invasive capacities, with a strong increase in MMP9, CXCR4 and VersicanV1. Let-7d- overexpression also reduced cell sensitivity to apoptosis induced by both serum-starvation and various chemotherapy drugs, concomitant with decrease in caspase-3 and increase in BCL2 expression. Our data suggest that let-7d in 3AB-OS-CSCs could induce plastic-transitions from CSCs-to-non-CSCs and vice-versa. To our knowledge this is the first study to comprehensively examine the expression and functions of let-7d in OS-CSCs. By showing that let-7d has both tumor suppressor and oncogenic functions in this context, our findings suggest that, before prospecting new therapeutic strategies based on let-7d modulation, it is urgent to better define its multiple functions. J. Cell. Physiol. 231: 1832-1841, 2016. © 2015 Wiley Periodicals, Inc.

HER2 induced EMT and tumorigenicity in breast epithelial progenitor cells is inhibited by coexpression of EGFR

The members of the epidermal growth factor receptor (EGFR) kinase family are important players in breast morphogenesis and cancer. EGFR2/HER2 and EGFR expression have a prognostic value in certain subtypes of breast cancer such as HER2-amplified, basal-like and luminal type B. Many clinically approved small molecular inhibitors and monoclonal antibodies have been designed to target HER2, EGFR or both. There is, however, still limited knowledge on how the two receptors are expressed in normal breast epithelium, what effects they have on cellular differentiation and how they participate in neoplastic transformation. D492 is a breast epithelial cell line with stem cell properties that can undergo epithelial to mesenchyme transition (EMT), generate luminal- and myoepithelial cells and form complex branching structures in three-dimensional (3D) culture. Here, we show that overexpression of HER2 in D492 (D492^HER2) resulted in EMT, loss of contact growth inhibition and increased oncogenic potential in vivo. HER2 overexpression, furthermore, inhibited endogenous EGFR expression. Re-introducing EGFR in D492^HER2 (D492^HER2/EGFR) partially reversed the mesenchymal state of the cells, as an epithelial phenotype reappeared both in 3D cultures and in vivo. The D492^HER2/EGFR xenografts grow slower than the D492^HER2 tumors, while overexpression of EGFR alone (D492^EGFR) was not oncogenic in vivo. Consistent with the EGFR-mediated epithelial phenotype, overexpression of EGFR drove the cells toward a myoepithelial phenotype in 3D culture. The effect of two clinically approved anti-HER2 and EGFR therapies, trastuzumab and cetuximab, was tested alone and in combination on D492^HER2 xenografts. While trastuzumab had a growth inhibitory effect compared with untreated control, the effect of cetuximab was limited. When administered in combination, the growth inhibitory effect of trastuzumab was less pronounced. Collectively, our data indicate that in HER2-overexpressing D492 cells, EGFR can behave as a tumor suppressor, by pushing the cells towards epithelial differentiation.

Is overexpression of TWIST, a transcriptional factor, a prognostic biomarker of head and neck carcinoma? Evidence from fifteen studies

TWIST, a basic helix-loop-helix transcription factor, has been indicated to play a critical role in the progression of numerous malignant disorders. Published data on the significance of TWIST expression in head and neck carcinoma (HNC) risk have yielded conflicting results. Thus, we conducted a quantitative meta-analysis to obtain a precise estimate of this subject. After systematic searching and screening, a total of fifteen studies using immunohistochemistry for TWIST detection were included. The results showed that TWIST positive expression rate in HNC tissues was higher than that in normal tissues. TWIST expression might have a correlation with clinical features such as low differentiation, advanced clinical stage, presence of lymph node metastasis, distant metastasis and local recurrence (P < 0.05) , but not with age, gender, T stage and smoking as well as drinking (P > 0.05). In addition, over-expression of TWIST was a prognostic factor for HNC (HR = 1.92, 95% CI = 1.13–3.25). The data suggested that TWIST might play critical roles in cancer progression and act as a prognostic factor for HNC patients.

Dicer ablation promotes a mesenchymal and invasive phenotype in bladder cancer cells

Dicer expression is frequently altered in cancer and affects a wide array of cellular functions acting as an oncogene or tumor suppressor in varying contexts. It has been shown that Dicer expression is also deregulated in urothelial cell carcinoma of the bladder (UCCB) but the nature of this deregulation differs between reports. The aim of the present study was to gain a better understanding of the role of Dicer in bladder cancer to help determine its contribution to the disease. The results showed that Dicer transcript levels were decreased in UCCB tumor tissues as compared to normal tissues, suggesting that Dicer is a tumor suppressor. However, consistent with previous results, we demonstrated that knockdown of Dicer decreases cell viability and increases the induction of apoptosis, suggesting that Dicer is an oncogene. To resolve this discrepancy, we assessed the effects of decreased Dicer expression on epithelial-to‑mesenchymal transition, migration and invasion. We showed that decreased Dicer levels promoted a mesenchymal phenotype and increased migration. Additionally, the results showed that Dicer protein ablation leads to increased cell invasion, higher levels of matrix metalloproteinase-2, and decreased levels of key miRNAs shown to inhibit invasion. The results of this study suggest that decreased Dicer levels may portend a more malignant phenotype.

Over-expression of TWIST, an epithelial-mesenchymal transition inducer, predicts poor survival in patients with oral carcinoma

TWIST, an epithelial-mesenchymal transition inducer, has been thought to play a critical role in the progression of a number of malignancies. Published studies reporting the association of TWIST expression with oral carcinoma risk has yielded conflicting results. Thus, we conducted a meta-analysis to address this controversy. After rigorous searching and screening, a total of seven studies were included. The results showed that the TWIST positive expression rate in oral cancer tissues was higher than that in the normal tissues. TWIST expression might have a correlation with clinical features such as low differentiation, advanced clinical stage, presence of lymph node metastasis and local recurrence, but not age, gender, T stage and smoking and drinking. The data suggested that TWIST might play critical roles in the cancer progression and act as a prognostic factor in oral cancer patients.

Interplay between microRNAs and WNT/β-catenin signalling pathway regulates epithelial-mesenchymal transition in cancer

The WNT/β-catenin signalling implies its significance in maintaining an epithelial cell phenotype, proper cell-cell junctions, and tissue homeostasis. Dysregulation of the members of this pathway involves in the development of cancer and an epithelial-mesenchymal transition (EMT) required for metastasis. Loss of E-cadherin is the major contributor to an EMT process and is largely influenced by the WNT/β-catenin signalling. An E-cadherin/β-catenin complex maintains epithelial integrity and disturbance of this complex and WNT/β-catenin pathway will ultimately lead to the nuclear translocation of β-catenin and transcription of EMT-promoting genes. WNT/β-catenin signalling is controlled by microRNAs (miRNAs), several of which are either up- or downregulated during EMT. The strong association between the expression of the WNT signalling components with miRNAs in the initiation and achievement of an EMT phenotype is suggestive of introducing these miRNAs as therapeutic targets against metastatic tumours. Therefore, this review aims to describe these putative miRNAs in altering the WNT/β-catenin signalling in EMT, and whether targeting them is a useful therapeutic option for human invasive tumours.

Pancreatic cancer stem cells: new insight into a stubborn disease

Resistance to conventional therapy and early distant metastasis contribute to the unsatisfactory prognosis of patients with pancreatic cancer. The concept of cancer stem cells (CSCs) brings new insights into cancer biology and therapy. Many studies have confirmed the important role of these stem cells in carcinogenesis and the development of hematopoietic and solid cancers. Recent studies have shown that CSCs regulate aggressive behavior, recurrence, and drug resistance in pancreatic cancer. Here, we review recent advances in pancreatic cancer stem cells (PCSCs) research. Particular attention is paid to the regulation mechanisms of pancreatic cancer stem cell functions, such as stemness-related signaling pathways, microRNAs, the epithelial-mesenchymal transition (EMT), and the tumor microenvironment, and the development of novel PCSCs targeted therapy. We seek to further understand PCSCs and explore potential therapeutic targets for pancreatic cancer.

EIF2C, Dicer, and Drosha are up-regulated along tumor progression and associated with poor prognosis in bladder carcinoma

EIF2C, Dicer, and Drosha are microRNA-regulating machinery components, which participate in microRNA intracellular process and transfer. Our research demonstrated the expression and clinical role of the microRNA-regulating machinery in bladder cancer. EIF2C1, EIF2C2, Dicer, and Drosha mRNA and protein levels were analyzed in 100 bladder carcinomas and 50 normal bladder tissues using quantitative polymerase chain reaction and Western blotting. EIF2C2, Dicer, and Drosha mRNAs and proteins were overexpressed in carcinoma compared with normal tissues, whereas EIF2C1 mRNA and protein were not obviously different. Moreover, immunohistochemistry was used to detect the expressions of EIF2C2, Dicer, and Drosha in 100 bladder carcinomas. There were higher EIF2C2, Dicer, and Drosha expressions in carcinomas than in the adjacent normal tissues, positive correlations being noted with clinical stage, histopathologic grade, and recurrence. Higher EIF2C2, Dicer, and Drosha expressions were related to shorter cancer-specific survival and shorter recurrence-free survival. Multivariate Cox analysis showed that EIF2C2 was an important risk factor in bladder cancer. In conclusion, EIF2C2, Dicer, and Drosha are more highly expressed in bladder carcinoma, promote the development of bladder cancer, and suggested a poor prognosis. Their clinical role in bladder carcinoma merits further research.

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

•

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

•

ERp29 shows a tumor suppressive function in primary tumor development.

•

ERp29 is potentially associated with distant metastasis in cancer.

•

ERp29 modulates cell survival against genotoxic stress.

•

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

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

Protein interactions of cortactin in relation to invadopodia formation in metastatic renal clear cell carcinoma

In the present study, we wanted to examine the predominant factor/s in the initiation of metastasis. We used samples of advanced grades of renal clear cell carcinoma with documented clinical history of vena caval spread as the experimental group. The major rationale for this selection is the fact that renal cell carcinoma metastasize extensively through the inferior vena cava up to the pulmonary bed and often exist as a continuous mass of metastatic tissue. As cortactin plays a significant role in invadopodia formation during initiation of metastasis, in the present study, we tested expression of cortactin and phospho(tyr421)-cortactin in different grades of renal cell clear carcinoma and examined its property to bind to actin. The findings of the present study suggest that the variations of the local physiological milieu are the driving forces for metastasis by enhancing molecular mechanisms for lamellipodia formation. We conclude that localization of cortactin in cancer cells and interaction between actin and its nucleators are crucial for cancer progression.