To differentiate or not--routes towards metastasis

ARID1A prevents squamous cell carcinoma initiation and chemoresistance by antagonizing pRb/E2F1/c-Myc-mediated cancer stemness

Squamous cell carcinoma (SCC) is defined as a category of aggressive malignancies arising from the squamous epithelium of various organs. Resistance to chemotherapies is a common feature of SCCs, which leads to a poor prognosis among SCC patients. Recently, studies have illustrated the essential tumor suppressive role of ARID1A in several cancer types, but its role in SCCs remains unclear. Cancer stemness has been recognized as a main reason for tumorigenesis and is commonly correlated with chemoresistance, yet the relationship between ARID1A and cancer stemness remains unknown. In this study, we showed that Arid1a conditional knockout mice had a high incidence of SCCs occurring in the tongue and esophagus. ARID1A depletion promoted tumor initiation and cancer stemness in human SCC cells. Mechanistic studies revealed that ARID1A blocked the interaction between cyclin-dependent kinases (CDKs) and retinoblastoma protein (Rb), reducing the phosphorylation of Rb. Dephosphorylated Rb suppressed E2F1 activity and then suppressed cancer stemness by inactivating c-Myc. Furthermore, we showed that ARID1A depletion significantly increased the chemoresistance of SCC and that a CDK inhibitor exhibited a favorable effect on rescuing the chemoresistance caused by ARID1A loss. Collectively, our study showed that ARID1A inhibits the cancer stemness of SCCs by competing with CDKs to bind with Rb to inhibit the E2F1/c-Myc pathway.

Metastasis and the evolution of dispersal

Despite significant progress in oncology, metastasis remains the leading cause of mortality of cancer patients. Understanding the foundations of this phenomenon could help contain or even prevent it. As suggested by many ecologists and cancer biologists, metastasis could be considered through the lens of biological dispersal: the movement of cancer cells from their birth site (the primary tumour) to other habitats where they resume proliferation (metastatic sites). However, whether this model can consistently be applied to the emergence and dynamics of metastasis remains unclear. Here, we provide a broad review of various aspects of the evolution of dispersal in ecosystems. We investigate whether similar ecological and evolutionary principles can be applied to metastasis, and how these processes may shape the spatio-temporal dynamics of disseminating cancer cells. We further discuss complementary hypotheses and propose experimental approaches to test the relevance of the evolutionary ecology of dispersal in studying metastasis.

Silencing expression of PHF14 in glioblastoma promotes apoptosis, mitigates proliferation and invasiveness via Wnt signal pathway

Background

The plant homeodomain (PHD) finger protein 14 (PHF14) is a vital member of PHD finger protein families. Abnormal expression of PHF14 has been identified in various cancers and is known to be implicated in the pathogenesis of tumors. This study investigates the role and the underlying mechanisms of PHF14 in GBM (glioblastoma multiforme).

Methods

Tissue microarrays and public databases interrogation were used to explore the relationship between the expression of PHF14 and GBM. Three stable PHF14-silenced cell lines (U251, U87MG and A172) were constructed to assess the biological functions changes of GBM cells in vitro. In addition, tumorigenicity in vivo was also performed using U87MG cell line. To understand the mechanism of action of PHF14, RNA-Seq, qRT-PCR, Western blot, IC50 assay and subsequent pathway analysis were performed.

Results

Our results showed that the expression of PHF14 was upregulated in glioma, especially in GBM. Overexpression of PHF14 translated to poor prognosis in glioma patients. In vitro assays revealed that silencing expression of PHF14 in glioma cells inhibited migration, invasiveness and proliferation and promoted cell apoptosis. Animal assay further confirmed that over-expression of PHF14 was a dismal prognostic factor. Analysis based on RNA-Seq suggested a PHF14-dependent regulation of Wnt signaling networks, which was further validated by qRT-PCR, Western blot and IC50 analysis. In addition, the mRNA expression of several key markers of EMT (epithelial–mesenchymal transition) and angiogenesis was found to change upon PHF14 silencing.

Conclusions

Our data provide a new insight into the biological significance of PHF14 in glioma and its potential application in therapy and diagnosis.

Distinct roles of PIK3CA in the enrichment and maintenance of cancer stem cells in head and neck squamous cell carcinoma

Recurrence and metastasis are the major causes of mortality in head and neck squamous cell carcinoma (HNSCC). It is suggested that cancer stem cells (CSCs) play pivotal roles in recurrence and metastasis. Thus, a greater understanding of the mechanisms of CSC regulation may provide opportunities to develop novel therapies for improving survival by controlling recurrence or metastasis. Here, we report that overexpression of the gene encoding the catalytic subunit of PI3K (PIK3CA), the most frequently amplified oncogene in HNSCC, promotes epithelial‐to‐mesenchymal transition and enriches the CSC population. However, PIK3CA is not required to maintain these traits and inhibition of the phosphatidylinositol 3‐kinase (PI3K) signaling pathway paradoxically promotes CSC population. Molecular analysis revealed that overexpression of PIK3CA activates multiple receptor tyrosine kinases (RTKs), in which ephrin receptors (Ephs), tropomyosin receptor kinases (TRK) and mast/stem cell growth factor receptor (c‐Kit) contribute to maintain CSC population. Accordingly, simultaneous inhibition of these RTKs using a multi‐kinase inhibitor ponatinib has a superior effect at eliminating the CSC population and reduces metastasis of PIK3CA‐overexpressing HNSCC cells. Our result suggests that co‐targeting of Ephs, TRKs and the c‐Kit pathway may be effective at eliminating the PI3K‐independent CSC population, thereby providing potential targets for future development of a novel anti‐CSC therapeutic approach for HNSCC patients, particularly for patients with PIK3CA amplification.

Epigenetic activation of hepatocyte growth factor is associated with epithelial-mesenchymal transition and clinical outcome in non-small cell lung cancer

Hepatocyte growth factor (HGF) expression is repressed in normal differentiated lung epithelial cells, but its expression is aberrantly upregulated in non-small cell lung cancer (NSCLC) and acts as a poor prognostic factor. The underlying molecular mechanisms of aberrant HGF expression are unclear. In this study, a novel differential methylation region located in the HGF promoter was identified, which was associated with aberrant HGF expression in NSCLC. The correlations of HGF promoter methylation detected by methylation specific PCR and HGF expression detected by immunohistochemistry with clinical outcomes were assessed in NSCLC patients. DNA methylation of the HGF promoter was correlated with the activation of HGF expression, which induced epithelial-mesenchymal transition, cell migration and invasion. According to the clinical correlation analysis in 63 NSCLC patients, those with high methylation were more likely to have stages III and IV (51.6% vs. 25.0%, P<0.05) and metastasis (57.5% vs. 16.7%, P<0.05) than patients with low methylation. In addition, compared with the protein marker of HGF expression, the DNA methylation marker of the HGF promoter had higher specificity for prognostic analysis of metastases in NSCLC. Our study indicated the regulatory mechanisms related to DNA methylation of the HGF promoter for HGF expression in NSCLC epithelial cells, and suggested that the DNA methylation signature of the HGF promoter could potentially be employed as a biomarker to improve the prognostic accuracy of NSCLC.

Why Be One Protein When You Can Affect Many? The Multiple Roles of YB-1 in Lung Cancer and Mesothelioma

Lung cancers and malignant pleural mesothelioma (MPM) have some of the worst 5-year survival rates of all cancer types, primarily due to a lack of effective treatment options for most patients. Targeted therapies have shown some promise in thoracic cancers, although efficacy is limited only to patients harboring specific mutations or target expression. Although a number of actionable mutations have now been identified, a large population of thoracic cancer patients have no therapeutic options outside of first-line chemotherapy. It is therefore crucial to identify alternative targets that might lead to the development of new ways of treating patients diagnosed with these diseases. The multifunctional oncoprotein Y-box binding protein-1 (YB-1) could serve as one such target. Recent studies also link this protein to many inherent behaviors of thoracic cancer cells such as proliferation, invasion, metastasis and involvement in cancer stem-like cells. Here, we review the regulation of YB-1 at the transcriptional, translational, post-translational and sub-cellular levels in thoracic cancer and discuss its potential use as a biomarker and therapeutic target.

Potential Role of MSC/Cancer Cell Fusion and EMT for Breast Cancer Stem Cell Formation

Solid tumors comprise of maturated cancer cells and self-renewing cancer stem-like cells (CSCs), which are associated with various other nontumorigenic cell populations in the tumor microenvironment. In addition to immune cells, endothelial cells, fibroblasts, and further cell types, mesenchymal stroma/stem-like cells (MSC) represent an important cell population recruited to tumor sites and predominantly interacting with the different cancer cells. Breast cancer models were among the first to reveal distinct properties of CSCs, however, the cellular process(es) through which these cells are generated, maintained, and expanded within neoplastic tissues remains incompletely understood. Here, we discuss several possible scenarios that are not mutually exclusive but may even act synergistically: fusion of cancer cells with MSC to yield hybrid cells and/or the induction of epithelial-mesenchymal transition (EMT) in breast cancer cells by MSC, which can relay signals for retrodifferentiation and eventually, the generation of breast CSCs (BCSCs). In either case, the consequences may be promotion of self-renewal capacity, tumor cell plasticity and heterogeneity, an increase in the cancer cells’ invasive and metastatic potential, and the acquisition of resistance mechanisms towards chemo- or radiotherapy. While specific signaling mechanisms involved in each of these properties remain to be elucidated, the present review article focusses on a potential involvement of cancer cell fusion and EMT in the development of breast cancer stem cells.

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

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

Protein kinase C inhibitors override ZEB1-induced chemoresistance in HCC

Epithelial-mesenchymal transition (EMT) is a process by which tumour cells lose epithelial characteristics, become mesenchymal and highly motile. EMT pathways also induce stem cell features and resistance to apoptosis. Identifying and targeting this pool of tumour cells is a major challenge. Protein kinase C (PKC) inhibition has been shown to eliminate breast cancer stem cells but has never been assessed in hepatocellular cancer (HCC). We investigated ZEB family of EMT inducer expression as a biomarker for metastatic HCC and evaluated the efficacy of PKC inhibitors for HCC treatment. We showed that ZEB1 positivity predicted patient survival in multiple cohorts and also validated as an independent biomarker of HCC metastasis. ZEB1-expressing HCC cell lines became resistant to conventional chemotherapeutic agents and were enriched in CD44high/CD24low cell population. ZEB1- or TGFβ-induced EMT increased PKCα abundance. Probing public databases ascertained a positive association of ZEB1 and PKCα expression in human HCC tumours. Inhibition of PKCα activity by small molecule inhibitors or by PKCA knockdown reduced viability of mesenchymal HCC cells in vitro and in vivo. Our results suggest that ZEB1 expression predicts survival and metastatic potential of HCC. Chemoresistant/mesenchymal HCC cells become addicted to PKC pathway and display sensitivity to PKC inhibitors such as UCN-01. Stratifying patients according to ZEB1 and combining UCN-01 with conventional chemotherapy may be an advantageous chemotherapeutic strategy.

Bone Metastases in Neuroendocrine Neoplasms: From Pathogenesis to Clinical Management

Bone represents a common site of metastases for several solid tumors. However, the ability of neuroendocrine neoplasms (NENs) to localize to bone has always been considered a rare and late event. Thanks to the improvement of therapeutic options, which results in longer survival, and of imaging techniques, particularly after the introduction of positron emission tomography (PET) with gallium peptides, the diagnosis of bone metastases (BMs) in NENs is increasing. The onset of BMs can be associated with severe skeletal complications that impair the patient’s quality of life. Moreover, BMs negatively affect the prognosis of NEN patients, bringing out the lack of curative treatment options for advanced NENs. The current knowledge on BMs in gastro-entero-pancreatic (GEP) and bronchopulmonary (BP) NENs is still scant and is derived from a few retrospective studies and case reports. This review aims to perform a critical analysis of the evidence regarding the role of BMs in GEP- and BP-NENs, focusing on the molecular mechanisms underlining the development of BMs, as well as clinical presentation, diagnosis, and treatment of BMs, in an attempt to provide suggestions that can be used in clinical practice.

Downregulated IGFBP7 facilitates liver metastasis by modulating epithelial‑mesenchymal transition in colon cancer

Distant metastasis is a major cause of cancer-associated mortality in patients with colon cancer. Insulin-like growth factor binding protein 7 (IGFBP7) has been identified as a crucial inhibitor of human cancer. However, the role of IGFBP7 in the pathogenesis of metastatic colon cancer has not been investigated. In the present study, the expression of IGFBP7 in 81 pairs of colon cancer tissues and adjacent normal tissues were investigated using immunohistochemistry. Furthermore, 24 pairs of primary colon cancer and matched liver metastasis tissues were analyzed. LοVο cells with IGFBP7-knockdown and HT-29 cells with IGFBP7-overexpression were employed. The expression levels of E-cadherin, N-cadherin and Vimentin were quantified and compared. Significant alterations in the expression of IGFBP7 between late stage (III + IV) colon cancer and adjacent normal colonic mucosa were observed. (P=0.031). The association between IGFBP7 and epithelial-mesenchymal transition (EMT) markers were validated in primary colon cancer and matched liver metastasis tissues. The invasive front of liver metastatic colon tissues revealed reduced IGFBP7 expression. Additionally, knockdown of IGFBP7 in LοVο cells resulted in decreased E-cadherin, and increased N-cadherin and Vimentin expression compared with the control group. Overexpression of IGFBP7 in HT-29 cells induced an upregulation of E-cadherin; however, the N-cadherin and Vimentin levels were decreased. In conclusion, the results of the present study suggested that IGFBP7 may prevent colon cancer metastasis by inhibiting EMT, and serves as a potential diagnostic marker and therapeutic target for patients with colon cancer.

E-cadherin is required for metastasis in multiple models of breast cancer

Metastasis is the major driver of cancer deaths and begins when cancer cells invade surrounding tissues. Invasion and metastasis have been proposed to initiate following loss of the intercellular adhesion protein, E-cadherin (E-cad)^1,2, based upon inverse correlations between in vitro migration and E-cad levels³. This hypothesis is inconsistent, however, with the observation that most breast cancers are invasive ductal carcinomas (IDC) and express E-cad in primary tumors and metastases⁴. To resolve this discrepancy, we tested the genetic requirement for E-cad in metastasis using murine and human models of both luminal and basal IDC. Here we show that E-cad promotes metastasis in IDC. While loss of E-cad increased invasion, it also reduced cancer cell proliferation and survival, circulating tumor cell number, seeding of cancer cells in distant organs, and metastasis formation. Transcriptionally, loss of E-cad was associated with upregulation of TGFβ, reactive oxygen, and apoptosis signaling pathways. At the cellular level, disseminating E-cad-negative cells exhibited nuclear enrichment of SMAD2/3, oxidative stress, and elevated apoptosis rates. Colony formation of E-cad-negative cells was rescued by inhibition of TGFβ receptor signaling, reactive oxygen accumulation, or apoptosis. Our results reveal that E-cad acts as a survival factor in IDC during the detachment, systemic dissemination, and seeding phases of metastasis by limiting reactive oxygen-mediated apoptosis. Identifying molecular strategies to inhibit E-cad mediated survival in metastatic breast cancer cells could potentially be a new therapeutic approach for breast cancer.

FAM83A signaling induces epithelial-mesenchymal transition by the PI3K/AKT/Snail pathway in NSCLC

Family with sequence similarity 83, member A (FAM83A), as a potential tumor promoter, was reported to contribute to the progression of several malignant tumors. However, the significance of FAM83A in invasion and metastasis of non-small cell lung cancer (NSCLC) remains largely unknown. In this study, we found that FAM83A expression was significantly increased in NSCLC tissues. High expression of FAM83A was positively associated with tumor metastasis and poor survival of NSCLC patients. Functional experiments revealed that FAM83A knockdown could suppress NSCLC cell migration and invasion both in vivo and in vitro. While opposite results were observed in FAM83A-transfected cells. Mechanically, we found that FAM83A promoted NSCLC cell migration and invasion by inducing epithelial-mesenchymal transition (EMT) via PI3K/ATK/Snail signaling. Rescue experiment demonstrated that inhibition of either AKT or Snail could partially counteract the promoting effect of FAM83A overexpression in NSCLC metastasis. Taken together, our findings are the first time to demonstrate that increased expression of FAM83A in NSCLC was correlated with EMT and tumor metastasis, which may provide a novel therapeutic target in NSCLC treatment.

Multi-Omics Characterization of the Spontaneous Mesenchymal-Epithelial Transition in the PMC42 Breast Cancer Cell Lines

Epithelial-mesenchymal plasticity (EMP), encompassing epithelial-mesenchymal transition (EMT) and mesenchymal-epithelial transition (MET), are considered critical events for cancer metastasis. We investigated chromosomal heterogeneity and chromosomal instability (CIN) profiles of two sister PMC42 breast cancer (BC) cell lines to assess the relationship between their karyotypes and EMP phenotypic plasticity. Karyotyping by GTG banding and exome sequencing were aligned with SWATH quantitative proteomics and existing RNA-sequencing data from the two PMC42 cell lines; the mesenchymal, parental PMC42-ET cell line and the spontaneously epithelially shifted PMC42-LA daughter cell line. These morphologically distinct PMC42 cell lines were also compared with five other BC cell lines (MDA-MB-231, SUM-159, T47D, MCF-7 and MDA-MB-468) for their expression of EMP and cell surface markers, and stemness and metabolic profiles. The findings suggest that the epithelially shifted cell line has a significantly altered ploidy of chromosomes 3 and 13, which is reflected in their transcriptomic and proteomic expression profiles. Loss of the TGFβR2 gene from chromosome 3 in the epithelial daughter cell line inhibits its EMT induction by TGF-β stimulus. Thus, integrative 'omics' characterization established that the PMC42 system is a relevant MET model and provides insights into the regulation of phenotypic plasticity in breast cancer.

The Transcription Factor Elf3 Is Essential for a Successful Mesenchymal to Epithelial Transition

The epithelial to mesenchymal transition (EMT) and the mesenchymal to epithelial transition (MET) are two critical biological processes that are involved in both physiological events such as embryogenesis and development and also pathological events such as tumorigenesis. They present with dramatic changes in cellular morphology and gene expression exhibiting acute changes in E-cadherin expression. Despite the comprehensive understanding of EMT, the regulation of MET is far from being understood. To find novel regulators of MET, we hypothesized that such factors would correlate with Cdh1 expression. Bioinformatics examination of several expression profiles suggested Elf3 as a strong candidate. Depletion of Elf3 at the onset of MET severely impaired the progression to the epithelial state. This MET defect was explained, in part, by the absence of E-cadherin at the plasma membrane. Moreover, during MET, ELF3 interacts with the Grhl3 promoter and activates its expression. Our findings present novel insights into the regulation of MET and reveal ELF3 as an indispensable guardian of the epithelial state. A better understanding of MET will, eventually, lead to better management of metastatic cancers.

Intracellular calprotectin (S100A8/A9) controls epithelial differentiation and caspase-mediated cleavage of EGFR in head and neck squamous cell carcinoma

OBJECTIVES

Calprotectin (S100A8/A9) appears to function as a tumor suppressor in head and neck squamous cell carcinoma (HNSCC) and expression in the carcinoma cells and patient survival rates are directly related. We seek to characterize the suppressive role of calprotectin in HNSCC.

AIMS

(1) Investigate changes in S100A8/A9 expression as oral carcinogenesis progresses and (2) determine whether intracellular calprotectin can regulate epidermal growth factor receptor (EGFR), a negative prognostic factor, in HNSCC.

MATERIALS AND METHODS

Using immunohistochemistry (IHC), S100A8/A9 was analyzed in HNSCC specimens (N = 46), including well-differentiated (WD, N = 19), moderately-differentiated (MD, N = 14), poorly-differentiated (PD, N = 5) and non-keratinizing/basaloid (NK/BAS, N = 8), and premalignant epithelial dysplasias (PED, N = 16). Similarly, EGFR was analyzed in HNSCCs (N = 21). To determine whether calprotectin and EGFR expression are mechanistically linked, TR146 HNSCC cells that are S100A8/A9-expressing or silenced (shRNA) were compared for EGFR levels and caspase-3/7 activity using western blotting and immunofluorescence microscopy.

RESULTS

In normal oral mucosal epithelium, S100A8/A9 stained strongly in the cytoplasm and nucleus of suprabasal cells; basal cells were consistently S100A8/A9 negative. In PED and HNSCC, S100A8/A9 expression was lower than in adjacent normal epithelial tissues (NAT) and declined progressively in WD, MD, PD and NK/BAS HNSCCs. S100A8/A9 and EGFR levels appeared inversely related, which was simulated in vitro when S100A8/A9 was silenced in TR146 cells. Silencing S100A8/A9 significantly reduced caspase-3/7 activity, whereas EGFR levels increased.

CONCLUSIONS

In HNSCC, S100A8/A9 is directly associated with cellular differentiation and appears to promote caspase-3/7-mediated cleavage of EGFR, which could explain why patients with S100A8/A9-high tumors survive longer.

Targeting Cancer Cell Metastasis by Converting Cancer Cells into Fat

Cancer is a systemic heterogeneous disease that can undergo several rounds of latency and activation. Malignant tumors evolve through dynamic responses to microenvironmental signals and development of resistance following therapeutic interventions. Cancer cell adaptation is required for cell survival during metastatic dissemination and outgrowth. Epithelial-mesenchymal transition (EMT) plays a major role in facilitating cell plasticity in cancer and allows cancer cells to escape chemotherapies and targeted therapies through dedifferentiation and signaling adaptation processes. In our recent study, we showed that breast cancer cells that have undergone EMT can be terminally differentiated into adipocytes using the PPARγ agonist rosiglitazone combined with the MEK inhibitor trametinib. The conversion of invasive cancer cells into adipocytes repressed primary tumor invasion and metastasis formation in mouse models of breast cancer. The transdifferentiated cancer cell-derived adipocytes were growth-arrested and lost their cellular plasticity. These results indicate the high potential of utilizing the increased cell plasticity inherent to invasive cancer cells for transdifferentiation therapy.

Expression of endoplasmic reticulum oxidoreductase 1-α in cholangiocarcinoma tissues and its effects on the proliferation and migration of cholangiocarcinoma cells

Abstract

Endoplasmic reticulum oxidoreductase 1-α (ERO1A) is a kind of hypoxia-induced endoplasmic reticulum oxidase that regulates translation and folding of oxidized proteins. This study aimed to explore the clinicopathological significance of ERO1A and the effect on the biological behavior of cholangiocarcinoma (CCA) cells.

Methods

Immunohistochemical staining was used to detect the expression of ERO1A, carcinoembryonic antigen (CEA), and carbohydrate antigen 19–9 (CA19-9) in cholangiocarcinoma. Immunofluorescence staining was performed to detect the subcellular localization of ERO1A in CCA cells. The expression of ERO1A in CAA cells after depletion or overexpression was verified by Western blot assay. Then, the effect of ERO1A on proliferation in CCA cells was verified by MTT assay and colony formation assay. Wound healing assays and migration assays were performed to detect the effect of ERO1A on cell migration ability. Finally, we explored the role of ERO1A in EMT and Akt/mTOR signaling pathway.

Results

In this study, our data demonstrated that ERO1A, CEA, and CA19-9 were expressed in cholangiocarcinoma tissues, and the positive rates were 95%, 95%, and 55%, respectively. The high expression of ERO1A is associated with clinical stage and pathological stage of CCA. In vitro data indicate that deletion of ERO1A can inhibit the proliferation and migration of CCA cells and vice versa. In addition, ERO1A has been shown to be closely related to EMT and Akt/mTOR pathways.

Conclusion

In summary, we found that high expression of ERO1A is associated with poor prognosis in patients, and ERO1A can promote the proliferation and migration of CCA cells. In conclusion, ERO1A can be used as an independent biomarker for predicting the prognosis of CCA.

Sleeping beauty genetic screen identifies miR-23b::BTBD7 gene interaction as crucial for colorectal cancer metastasis

Background

Metastatic colorectal cancer (CRC) remains a deadly disease. Identifying locally advanced CRC patients with high risk of developing metastasis and improving outcome of metastatic CRC patients require discovering master regulators of metastasis. In this context, the non-coding part of the human genome is still largely unexplored.

Methods

To interrogate the non-coding part of the human genome and disclose regulators of CRC metastasis, we combined a transposon-based forward genetic screen with a novel in vitro assay, which forces cells to grow deprived of cell-substrate and cell-cell contacts (i.e. forced single cell suspension assay - fSCS).

Findings

We proved that fSCS selects CRC cells with mesenchymal and pro-metastatic traits. Moreover, we found that the transposon insertions conferred CRC cells resistance to fSCS and thus metastatic advantage. Among the retrieved transposon insertions, we demonstrated that the one located in the 3′UTR of BTBD7 disrupts miR-23b::BTBD7 interaction and contributes to pro-metastatic traits. In addition, miR-23b and BTBD7 correlate with CRC metastasis both in preclinical experiments and in clinical samples.

Interpretation

fSCS is a simple and scalable in vitro assay to investigate pro-metastatic traits and transposon-based genetic screens can interrogate the non-coding part of the human genome (e.g. miRNA::target interactions). Finally, both Btbd7 and miR-23b represent promising prognostic biomarkers and therapeutic targets in CRC.

Fund

This work was supported by Marie Curie Actions (CIG n. 303877) and Friuli Venezia Giulia region (Grant Agreement n°245574), Italian Association for Cancer Research (AIRC, MFAG n°13589), Italian Ministry of Health (GR-2010-2319387 and PE-2016-02361040) and 5x1000 to CRO Aviano.

Uncoupling Traditional Functionalities of Metastasis: The Parting of Ways with Real-Time Assays

The experimental evaluation of metastasis overly focuses on the gain of migratory and invasive properties, while disregarding the contributions of cellular plasticity, extra-cellular matrix heterogeneity, niche interactions, and tissue architecture. Traditional cell-based assays often restrict the inclusion of these processes and warrant the implementation of approaches that provide an enhanced spatiotemporal resolution of the metastatic cascade. Time lapse imaging represents such an underutilized approach in cancer biology, especially in the context of disease progression. The inclusion of time lapse microscopy and microfluidic devices in routine assays has recently discerned several nuances of the metastatic cascade. Our review emphasizes that a complete comprehension of metastasis in view of evolving ideologies necessitates (i) the use of appropriate, context-specific assays and understanding their inherent limitations; (ii) cautious derivation of inferences to avoid erroneous/overestimated clinical extrapolations; (iii) corroboration between multiple assay outputs to gauge metastatic potential; and (iv) the development of protocols with improved in situ implications. We further believe that the adoption of improved quantitative approaches in these assays can generate predictive algorithms that may expedite therapeutic strategies targeting metastasis via the development of disease relevant model systems. Such approaches could potentiate the restructuring of the cancer metastasis paradigm through an emphasis on the development of next-generation real-time assays.

Tspan8 is expressed in breast cancer and regulates E-cadherin/catenin signalling and metastasis accompanied by increased circulating extracellular vesicles

Tspan8 exhibits a functional role in many cancer types including pancreatic, colorectal, oesophagus carcinoma, and melanoma. We present a first study on the expression and function of Tspan8 in breast cancer. Tspan8 protein was present in the majority of human primary breast cancer lesions and metastases in the brain, bone, lung, and liver. In a syngeneic rat breast cancer model, Tspan8⁺ tumours formed multiple liver and spleen metastases, while Tspan8⁻ tumours exhibited a significantly diminished ability to metastasise, indicating a role of Tspan8 in metastases. Addressing the underlying molecular mechanisms, we discovered that Tspan8 can mediate up‐regulation of E‐cadherin and down‐regulation of Twist, p120‐catenin, and β‐catenin target genes accompanied by the change of cell phenotype, resembling the mesenchymal–epithelial transition. Furthermore, Tspan8⁺ cells exhibited enhanced cell–cell adhesion, diminished motility, and decreased sensitivity to irradiation. As a regulator of the content and function of extracellular vesicles (EVs), Tspan8 mediated a several‐fold increase in EV number in cell culture and the circulation of tumour‐bearing animals. We observed increased protein levels of E‐cadherin and p120‐catenin in these EVs; furthermore, Tspan8 and p120‐catenin were co‐immunoprecipitated, indicating that they may interact with each other. Altogether, our findings show the presence of Tspan8 in breast cancer primary lesion and metastases and indicate its role as a regulator of cell behaviour and EV release in breast cancer. © 2019 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

The Role of Epithelial-to-Mesenchymal Plasticity in Ovarian Cancer Progression and Therapy Resistance

Ovarian cancer is the most lethal of all gynecologic malignancies and the eighth leading cause of cancer-related deaths among women worldwide. The main reasons for this poor prognosis are late diagnosis; when the disease is already in an advanced stage, and the frequent development of resistance to current chemotherapeutic regimens. Growing evidence demonstrates that apart from its role in ovarian cancer progression, epithelial-to-mesenchymal transition (EMT) can promote chemotherapy resistance. In this review, we will highlight the contribution of EMT to the distinct steps of ovarian cancer progression. In addition, we will review the different types of ovarian cancer resistance to therapy with particular attention to EMT-mediated mechanisms such as cell fate transitions, enhancement of cancer cell survival, and upregulation of genes related to drug resistance. Preclinical studies of anti-EMT therapies have yielded promising results. However, before anti-EMT therapies can be effectively implemented in clinical trials, more research is needed to elucidate the mechanisms leading to EMT-induced therapy resistance.

Next Viable Routes to Targeting Pancreatic Cancer Stemness: Learning from Clinical Setbacks

Pancreatic ductal adenocarcinoma (PDAC) is a devastating and highly aggressive malignancy. Existing therapeutic strategies only provide a small survival benefit in patients with PDAC. Laboratory and clinical research have identified various populations of stem-cell-like cancer cells or cancer stem cells (CSCs) as the driving force of PDAC progression, treatment-resistance, and metastasis. Whilst a number of therapeutics aiming at inhibiting or killing CSCs have been developed over the past decade, a series of notable clinical trial setbacks have led to their deprioritization from the pipelines, triggering efforts to refine the current CSC model and exploit alternative therapeutic strategies. This review describes the current and the evolving models of pancreatic CSCs (panCSCs) and the potential factors that hamper the clinical development of panCSC-targeted therapies, emphasizing the heterogeneity, the plasticity, and the non-binary pattern of cancer stemness, as well as the desmoplastic stroma impeding drug penetration. We summarized novel and promising therapeutic strategies implicated by the works of our groups and others' that may overcome these hurdles and have shown efficacies in preclinical models of PDAC, emphasizing the unique advantages of targeting the stroma-engendered panCSC-niches and metronomic chemotherapy. Finally, we proposed feasible clinical trial strategies and biomarkers that can guide the next-generation clinical trials.

Tucidinostat plus exemestane for postmenopausal patients with advanced, hormone receptor-positive breast cancer (ACE): a randomised, double-blind, placebo-controlled, phase 3 trial

BACKGROUND

Tucidinostat (formerly known as chidamide) is an oral subtype-selective histone deacetylase inhibitor. In an exploratory study, the combination of tucidinostat with exemestane showed preliminary signs of encouraging anti-tumour activity in patients with advanced hormone receptor-positive breast cancer. To build on these findings, we aimed to assess the efficacy and safety of this combination in a randomised trial in a larger population of postmenopausal patients with advanced, hormone receptor-positive breast cancer.

METHODS

We did the randomised, double-blind, placebo-controlled, phase 3 ACE trial at 22 specialist cancer centres in China. Eligible patients were postmenopausal women (aged ≥60 years or aged <60 years if their serum follicle-stimulating hormone and oestradiol concentrations were within postmenopausal ranges) with hormone receptor-positive, HER2-negative breast cancer, whose disease had relapsed or progressed after at least one endocrine therapy (either in advanced or metastatic or adjuvant setting), and who had at least one measurable lesion, adequate organ function, Eastern Cooperative Oncology Group (ECOG) performance status of 0-1, and adequate haematological and biochemical parameters. Endocrine therapy did not have to be the most recent therapy before randomisation, but recurrence or progression after the most recent therapy was a prerequisite. Patients were randomly assigned (2:1) by a dynamic randomisation scheme via an interactive web-response system to receive 30 mg oral tucidinostat or placebo twice weekly. All patients in both groups also received 25 mg oral exemestane daily. Randomisation was stratified according to the presence of visceral metastases (yes vs no). Patients, investigators, study site staff, and the sponsor were masked to treatment assignment. The primary endpoint was investigator-assessed progression-free survival. Efficacy analyses were done in the full analysis set population, comprising all patients who received at least one dose of any study treatment, and safety analyses were done in all patients who received at least one dose of any study treatment and for whom at least one safety case report form was available. This study is registered with ClinicalTrials.gov, number NCT02482753. The study has reached the required number of events for final analysis of the primary endpoint. The trial is no longer enrolling patients, but follow-up for investigation of overall survival is ongoing.

FINDINGS

Between July 20, 2015, and June 26, 2017, 365 patients were enrolled and randomly assigned, 244 to the tucidinostat group and 121 to the placebo group. The median duration of follow-up was 13·9 months (IQR 9·8-17·5). Investigator-assessed median progression-free survival was 7·4 months (95% CI 5·5-9·2) in the tucidinostat group and 3·8 months (3·7-5·5) in the placebo group (HR 0·75 [95% CI 0·58-0·98]; p=0·033). The most common grade 3 or 4 adverse events in either group were neutropenia (124 [51%] of 244 patients in the tucidinostat group vs three [2%] of 121 patients in the placebo group), thrombocytopenia (67 [27%] vs three [2%]), and leucopenia (46 [19%] vs three [2%]). Serious adverse events of any cause occurred in 51 (21%) of 244 patients in the tucidinostat group and seven (6%) of 121 patients in the placebo group. No treatment-related deaths were reported.

INTERPRETATION

Tucidinostat plus exemestane improved progression-free survival compared with placebo plus exemestane in patients with advanced, hormone receptor-positive, HER2-negative breast cancer that progressed after previous endocrine therapy. Grade 3-4 haematological adverse events were more common in the tucidinostat plus exemestane group than in the placebo plus exemestane group. Tucidinostat plus exemestane could represent a new treatment option for these patients.

FUNDING

Chipscreen Biosciences.

The Crosstalk Between Cell Adhesion and Cancer Metabolism

Cancer cells preferentially use aerobic glycolysis over mitochondria oxidative phosphorylation for energy production, and this metabolic reprogramming is currently recognized as a hallmark of cancer. Oncogenic signaling frequently converges with this metabolic shift, increasing cancer cells' ability to produce building blocks and energy, as well as to maintain redox homeostasis. Alterations in cell-cell and cell-extracellular matrix (ECM) adhesion promote cancer cell invasion, intravasation, anchorage-independent survival in circulation, and extravasation, as well as homing in a distant organ. Importantly, during this multi-step metastatic process, cells need to induce metabolic rewiring, in order to produce the energy needed, as well as to impair oxidative stress. Although the individual implications of adhesion molecules and metabolic reprogramming in cancer have been widely explored over the years, the crosstalk between cell adhesion molecular machinery and metabolic pathways is far from being clearly understood, in both normal and cancer contexts. This review summarizes our understanding about the influence of cell-cell and cell-matrix adhesion in the metabolic behavior of cancer cells, with a special focus concerning the role of classical cadherins, such as Epithelial (E)-cadherin and Placental (P)-cadherin.

NMIIA promotes tumor growth and metastasis by activating the Wnt/β-catenin signaling pathway and EMT in pancreatic cancer

Non-muscle myosin IIA (NMIIA) protein plays an important role in cell cytokinesis and cell migration. The role and underlying regulatory mechanisms of NMIIA in pancreatic cancer (PC) remain elusive. We found that NMIIA is highly expressed in PC tissues and contributes to PC poor progression by using open microarray datasets from the Gene Expression Omnibus (GEO), The Cancer Genome Atlas (TCGA), and PC tissue arrays. NMIIA regulates β-catenin mediated EMT to promote the proliferation, migration, invasion, and sphere formation of PC cells in vitro and in vivo. NMIIA controls the β-catenin transcriptional activity by interacting with β-catenin. Moreover, MEK/ERK signaling is critical in MLC2 (Ser19) phosphorylation, which can mediate NMIIA activity and regulate Wnt/β-catenin signaling. These findings highlight the significance of NMIIA in tumor regression and implicate NMIIA as a promising candidate for PC treatment.

Epithelial Mesenchymal Transition in Tumor Metastasis

Metastasis is the major cause of cancer-related deaths; therefore, the prevention and treatment of metastasis are fundamental to improving clinical outcomes. Epithelial mesenchymal transition (EMT), an evolutionarily conserved developmental program, has been implicated in carcinogenesis and confers metastatic properties upon cancer cells by enhancing mobility, invasion, and resistance to apoptotic stimuli. Furthermore, EMT-derived tumor cells acquire stem cell properties and exhibit marked therapeutic resistance. Given these attributes, the complex biological process of EMT has been heralded as a key hallmark of carcinogenesis, and targeting EMT pathways constitutes an attractive strategy for cancer treatment. However, demonstrating the necessity of EMT for metastasis in vivo has been technically challenging, and recent efforts to demonstrate a functional contribution of EMT to metastasis have yielded unexpected results. Therefore, determining the functional role of EMT in metastasis remains an area of active investigation. Studies using improved lineage tracing systems, dynamic in vivo imaging, and clinically relevant in vivo models have the potential to uncover the direct link between EMT and metastasis. This review focuses primarily on recent advances in and emerging concepts of the biology of EMT in metastasis in vivo and discusses future directions in the context of novel diagnostic and therapeutic opportunities.

Concomitant Expression of Prolactin Receptor and TGFβ Receptors in Breast Cancer: Association with Less Aggressive Phenotype and Favorable Patient Outcome

The epithelial–mesenchymal transition (EMT) process is known to play an essential role in tumor progression, metastasis and resistance to therapy. This report evaluated the prognostic value of co-expression of the receptor for prolactin (PRLR), a suppressor of EMT, and the receptors for transforming growth factor β (TGFβRI and TGFβRII), an inducer of EMT, in association with different clinicopathological parameters using TMA of 102 breast cancer patients and publicly available data on breast cancer patients. Interestingly, the results revealed that malignant tissues had significantly lower levels of concomitant protein expression of these receptors in comparison to normal/benign breast tissue. In addition, a higher level of concomitant expression was also observed in less aggressive breast cancer phenotypes, including low grade tumors, luminal breast cancer subtype, and less advanced stages of the disease (lymph node negative and early stages). Moreover, the results also showed that the expression of a gene signature composed of PRLR/TGFβRI/TGFβRII correlates more with differentiated grade I tumors, and identified a subset of patients showing better survival outcomes evident in luminal B and HER-2 enriched molecular subtypes. Together, these results indicate that loss of the co-expression of PRLR, TGFβRI and TGFβRII is indicative of aggressiveness and poor patient survival outcomes in breast cancer.

Acquisition of a hybrid E/M state is essential for tumorigenicity of basal breast cancer cells

As carcinoma cells progress toward high-grade malignancy, they often if not invariably activate the cell-biological program termed the epithelial–mesenchymal transition (EMT). We discovered that, both in vitro and in vivo, certain breast cancer cells can reside stably and thus with low cell plasticity in a highly tumorigenic, hybrid epithelial/mesenchymal state driven by Snail and canonical Wnt signaling. However, if such cells are forced into a fully mesenchymal state, this results in a poorly tumorigenic cell population under the control of Zeb1 and noncanonical Wnt signaling. These findings suggest that the design of future therapeutic approaches will need to consider the various subpopulations of carcinoma cells that reside at various positions along the E–M spectrum.

Carcinoma cells residing in an intermediate phenotypic state along the epithelial–mesenchymal (E–M) spectrum are associated with malignant phenotypes, such as invasiveness, tumor-initiating ability, and metastatic dissemination. Using the recently described CD104⁺/CD44^hi antigen marker combination, we isolated highly tumorigenic breast cancer cells residing stably—both in vitro and in vivo—in an intermediate phenotypic state and coexpressing both epithelial (E) and mesenchymal (M) markers. We demonstrate that tumorigenicity depends on individual cells residing in this E/M hybrid state and cannot be phenocopied by mixing two cell populations that reside stably at the two ends of the spectrum, i.e., in the E and in the M state. Hence, residence in a specific intermediate state along the E–M spectrum rather than phenotypic plasticity appears critical to the expression of tumor-initiating capacity. Acquisition of this E/M hybrid state is facilitated by the differential expression of EMT-inducing transcription factors (EMT-TFs) and is accompanied by the expression of adult stem cell programs, notably, active canonical Wnt signaling. Furthermore, transition from the highly tumorigenic E/M state to a fully mesenchymal phenotype, achieved by constitutive ectopic expression of Zeb1, is sufficient to drive cells out of the E/M hybrid state into a highly mesenchymal state, which is accompanied by a substantial loss of tumorigenicity and a switch from canonical to noncanonical Wnt signaling. Identifying the gatekeepers of the various phenotypic states arrayed along the E–M spectrum is likely to prove useful in developing therapeutic approaches that operate by shifting cancer cells between distinct states along this spectrum.

IL-6 promotes endometrial cancer cells invasion and migration through signal transducers and activators of transcription 3 signaling pathway

Interleukin (IL)-6 is the most well-known traditional activator of activating signal transducers and activators of transcription 3 (Stat3). They have been proved to promote cancer progression in several human cancers. However, their exact roles in endometrial cancer have not been elucidated clearly. In this study, we aimed to investigate the role of IL-6/Stat3 signaling pathway in human endometrial cancer cells invasion and migration. We demonstrated that Stat3 is activated in endometrial cancer cell lines. To investigate the role of Stat3 in endometrial cancer invasive capacity, we used Stat3 inhibitor Stattic and found that Stattic significantly inhibited the migration and invasion of endometrial cancer cells elevated by IL-6. Furthermore, we showed that Stat3 inhibitor significantly decreased the expression of MMP2 enhanced by IL-6, indicating that IL-6 promoted endometrial cancer invasion and migration by Stat3-induced MMP2 upregulation. Taken together, our findings indicate that targeting IL-6/Stat3 pathway might be a potentially effective therapeutic strategy for treating endometrial cancer.

Pancreatic cancer-initiating cell exosome message transfer into noncancer-initiating cells: the importance of CD44v6 in reprogramming

BACKGROUND

Cancer-initiating cell (CIC) exosomes (CIC-TEX) are suggested reprogramming Non-CIC. Mode of message transfer and engagement of CIC-markers being disputed, we elaborated the impact of CD44v6 and Tspan8 on the response of Non-CIC.

METHODS

Non-metastasizing CD44v6- and Tspan8-knockdown (kd) pancreatic cancer cells served as Non-CIC. CIC-TEX coculture-induced changes were evaluated by deep-sequencing and functional assays. Tumor progression was surveyed during in vivo CIC-TEX treatment.

RESULTS

Deep-sequencing of CIC-TEX-cocultured CD44v6kd-Non-CIC revealed pronounced mRNA changes in signaling, transport, transcription and translation; altered miRNA affected metabolism, signaling and transcription. CIC-TEX coculture-induced changes in Tspan8kd-Non-CIC mostly relied on CIC-TEX-Tspan8 being required for targeting. CIC-TEX transfer supported apoptosis resistance and significantly promoted epithelial mesenchymal transition, migration, invasion and (lymph)angiogenesis of the kd Non-CIC in vitro and in vivo, deep-sequencing allowing individual mRNA and miRNA assignment to altered functions. Importantly, CIC-TEX act as a hub, initiated by CD44v6-dependent RTK, GPCR and integrin activation and involving CD44v6-assisted transcription and RNA processing. Accordingly, a kinase inhibitor hampered CIC-TEX-fostered tumor progression, which was backed by an anti-Tspan8 blockade of CIC-TEX binding.

CONCLUSIONS

This in depth report on the in vitro and in vivo impact of CIC-TEX on CD44v6kd and Tspan8kd Non-CIC unravels hub CIC-TEX activity, highlighting a prominent contribution of the CIC-markers CD44v6 to signaling cascade activation, transcription, translation and miRNA processing in Non-CIC and of Tspan8 to CIC-TEX targeting. Blocking CIC-TEX binding/uptake and uptake-initiated target cell activation significantly mitigated the deleterious CIC-TEX impact on CD44v6kd and Tspan8kd Non-CIC.

CUL4B promotes prostate cancer progression by forming positive feedback loop with SOX4

How to distinguish indolent from aggressive disease remains a great challenge in prostate cancer (PCa) management. Cullin 4B (CUL4B) is a scaffold protein and exhibits oncogenic activity in a variety of human malignancies. In this study, we utilized PCa tissue specimens, cell lines and xenograft models to determine whether CUL4B contributes to PCa progression and metastasis. Here, we show that CUL4B expression highly correlates with the aggressiveness of PCa. CUL4B expression promotes proliferation, epithelial−mesenchymal transition, and metastatic potential of PCa cells, whereas CUL4B knockdown inhibits. Mechanically, CUL4B positively regulates SOX4, a key regulator in PCa, through epigenetic silencing of miR-204. In turn, SOX4 upregulates CUL4B expression through transcriptional activation, thereby fulfilling a positive feedback loop. Clinically, CUL4B+/SOX4+ defines a subset of PCa patients with poor prognosis. Bioinformatics analysis further reveals that Wnt/ß-catenin activation signature is enriched in CUL4B+/SOX4+ patient subgroup. Intriguingly, Wnt inhibitors significantly attenuates oncogenic capacities of CUL4B in vitro and in vivo. Together, our study identifies CUL4B as a key modulator of aggressive PCa by a positive feedback loop that interacts with SOX4. This regulatory circuit may have a crucial role in PCa progression.

HERC3-Mediated SMAD7 Ubiquitination Degradation Promotes Autophagy-Induced EMT and Chemoresistance in Glioblastoma

PURPOSE

Glioblastoma, a common malignant intracranial tumor, has the most dismal prognosis. Autophagy was reported to act as a survival-promoting mechanism in gliomas by inducing epithelial-to-mesenchymal transition (EMT). Here, we determined the critical molecules involved in autophagy-induced EMT and elucidated the possible mechanism of chemoradiotherapy resistance and tumor recurrence.

EXPERIMENTAL DESIGN

We used isobaric tags for relative and absolute quantitation to identify the critical proteins and pathway mediating EMT via autophagy inducer treatment, and tested the expression of these proteins using tissue microarray of gliomas and clinical glioblastoma samples as well as tissues and cells separated from the core lesion and tumor-peripheral region. Analysis of the Cancer Genome Atlas database and 110 glioblastoma cases revealed the prognostic value of these molecules. The functional role of these critical molecules was further confirmed by in vitro experiments and intracranial xenograft in nude mice.

RESULTS

Autophagy inducers significantly upregulated the expression of HERC3, which promotes ubiquitination-mediated degradation of SMAD7 in an autolysosome-dependent manner. The corresponding increase in p-SMAD2/3 level and TGFβ pathway activation finally induced EMT in cell lines and primary glioblastoma cells. Moreover, HERC3 overexpression was observed in pseudo-palisade cells surrounding tumor necrosis and in tumor-adjacent tissue; high HERC3 and low SMAD7 levels predicted poor clinical outcome in glioblastoma; xenograft of nude mice and in vitro experiments confirmed these findings.

CONCLUSIONS

Together, our findings reveal the indispensable role of HERC3 in regulating canonical SMAD2/3-dependent TGFβ pathway involvement in autophagy-induced EMT, providing insights toward a better understanding of the mechanism of resistance to temozolomide and peripheral recurrence of glioblastoma.

EMT Regulation by Autophagy: A New Perspective in Glioblastoma Biology

Epithelial-to-mesenchymal transition (EMT) and its reverse process MET naturally occur during development and in tissue repair in vertebrates. EMT is also recognized as the crucial event by which cancer cells acquire an invasive phenotype through the activation of specific transcription factors and signalling pathways. Even though glial cells have a mesenchymal phenotype, an EMT-like process tends to exacerbate it during gliomagenesis and progression to more aggressive stages of the disease. Autophagy is an evolutionary conserved degradative process that cells use in order to maintain a proper homeostasis, and defects in autophagy have been associated to several pathologies including cancer. Besides modulating cell resistance or sensitivity to therapy, autophagy also affects the migration and invasion capabilities of tumor cells. Despite this evidence, few papers are present in literature about the involvement of autophagy in EMT-like processes in glioblastoma (GBM) so far. This review summarizes the current understanding of the interplay between autophagy and EMT in cancer, with special regard to GBM model. As the invasive behaviour is a hallmark of GBM aggressiveness, defining a new link between autophagy and EMT can open a novel scenario for targeting these processes in future therapeutical approaches.

Apical-basal polarity inhibits epithelial-mesenchymal transition and tumour metastasis by PAR-complex-mediated SNAI1 degradation

Loss of apical-basal polarity and activation of epithelial-mesenchymal transition (EMT) both contribute to carcinoma progression and metastasis. Here, we report that apical-basal polarity inhibits EMT to suppress metastatic dissemination. Using mouse and human epithelial three-dimensional organoid cultures, we show that the PAR-atypical protein kinase C (aPKC) polarity complex inhibits EMT and invasion by promoting degradation of the SNAIL family protein SNAI1. Under intact apical-basal polarity, aPKC kinases phosphorylate S249 of SNAI1, which leads to protein degradation. Loss of apical-basal polarity prevents aPKC-mediated SNAI1 phosphorylation and stabilizes the SNAI1 protein to promote EMT and invasion. In human breast tumour xenografts, inhibition of the PAR-complex-mediated SNAI1 degradation mechanism promotes tumour invasion and metastasis. Analyses of human breast tissue samples reveal negative correlations between PAR3 and SNAI1 protein levels. Our results demonstrate that apical-basal polarity functions as a critical checkpoint of EMT to precisely control epithelial-mesenchymal plasticity during tumour metastasis.

The prognostic value of Tiam1 correlates with its roles in epithelial-mesenchymal transition progression and angiogenesis in lung adenocarcinoma

Background

Tiam1 has been identified as an oncogene and acts as an activator of GTPase Rac. Tiam1 was reported to be a promoter of cancer progression in various cancer types, while in lung adenocarcinoma, its mechanism of action is poorly understood.

Materials and Methods

Immunohistochemistry staining and Western blot assay were used to determine Tiam1 expression in lung adenocarcinoma tissues, and its association with prognosis was determined by statistical analysis. We depleted Tiam1 in both A549 and H1975 cancer cell lines. Carboxyfluorescein diacetate succinimidyl ester staining and colony formation assays were used to evaluate its impact on cell proliferation ability after depletion. Transwell migration assay and wound healing assays were performed to determine its impact on migration ability of both cell lines. Western blot assay and immunofluorescence staining were used to analyze the association between Tiam1 and epithelial-mesenchymal transition (EMT) progression. Tube formation assay and vasculogenic mimicry assay were used to show the impact of Tiam1 depletion on cancer angiogenesis.

Results

In this study, we demonstrated that Tiam1 overexpression in lung adenocarcinoma was significantly associated with advanced tumor grade and poor prognosis. In vitro assays indicated that Tiam1 depletion significantly inhibited cell proliferation, colony formation, and migration capacities in A549 and H1975 cells. Further investigations revealed that Tiam1 plays an important role in EMT program enhancement, angiogenesis, and accelerated tumor progression. Notably, Tiam1 depletion in cancer cells strongly inhibited human umbilical vein endothelial cell angiogenesis and vasculogenic mimicry capacities of both cancer cell lines.

Conclusion

Tiam1 overexpression is associated with lung adenocarcinoma progression and may indicate poor prognosis. Tiam1 accelerated tumor progression due to EMT and angiogenesis enhancement. Our data may provide a novel therapeutic target for lung adenocarcinoma.

TOX3 inhibits cancer cell migration and invasion via transcriptional regulation of SNAI1 and SNAI2 in clear cell renal cell carcinoma

Studies on the mechanism of clear cell renal cell carcinoma (ccRCC) progression are lacking. In this study, TOX3 was identified as a novel cancer suppressor gene in ccRCC. Hypermethylation of CpG probes in the promoter region was associated with the functional loss of TOX3 in ccRCC cancer tissues. Downregulation of TOX3 mRNA was strongly associated with poor clinical outcomes in ccRCC. Immunohistochemistry confirmed TOX3 was downregulated in primary tumors without metastasis (n = 126) and further downregulated in primary metastatic tumors (n = 23) compared with adjacent noncancerous tissues (n = 92). In vitro, overexpression of TOX3 inhibited RCC cell growth, migration and invasion. Mechanistic investigations showed that TOX3 deficiency facilitates the epithelial-mesenchymal transition due to impairment of transcriptional repression of SNAIL members SNAI1 and SNAI2 and promotes cancer cell migration and invasion. In vivo, restoring TOX3 expression reduced lung metastatic lesions and prolonged survival of mice. TOX3 combined with SNAI1 or SNAI2 predicted overall survival in ccRCC patients. Blockage of this pathway could be a promising therapeutic target for advanced ccRCC.

Gain Fat-Lose Metastasis: Converting Invasive Breast Cancer Cells into Adipocytes Inhibits Cancer Metastasis

Cancer cell plasticity facilitates the development of therapy resistance and malignant progression. De-differentiation processes, such as an epithelial-mesenchymal transition (EMT), are known to enhance cellular plasticity. Here, we demonstrate that cancer cell plasticity can be exploited therapeutically by forcing the trans-differentiation of EMT-derived breast cancer cells into post-mitotic and functional adipocytes. Delineation of the molecular pathways underlying such trans-differentiation has motivated a combination therapy with MEK inhibitors and the anti-diabetic drug Rosiglitazone in various mouse models of murine and human breast cancer in vivo. This combination therapy provokes the conversion of invasive and disseminating cancer cells into post-mitotic adipocytes leading to the repression of primary tumor invasion and metastasis formation.

PRRX1 Regulates Cellular Phenotype Plasticity and Dormancy of Head and Neck Squamous Cell Carcinoma Through miR-642b-3p

BACKGROUND: Dormancy is one characteristic of cancer cells to make patients remain asymptomatic before metastasis and relapse, which is closely related to the survival rate of cancer patients, including head and neck squamous cell carcinoma (HNSCC). PRRX1 has previously been implicated in the invasion and metastasis of the epithelial-mesenchymal transition (EMT) process in different types of human carcinoma. However, whether PRRX1 can regulate cancer dormancy and its reactivation, leading to the migration and invasion of HNSCC cells, remains elusive. The aim of this study was to determine the role of PRRX1 in cellular phenotype plasticity and cancer dormancy of HNSCC cells and its association with miRNAs in HNSCC. METHODS: The expression of PRRX1 was detected by immunohistochemical staining in primary HNSCC samples and the metastatic lymph nodes. Meanwhile, the role of PRRX1 and its relationship with miR-642b-3p and EMT in cellular phenotype plasticity and cancer dormancy of HNSCC were investigated in vitro and in vivo. RESULTS: PRRX1 was significantly higher at the invasive front of HNSCC samples compared with the metastatic lymph nodes, and such switch process was accompanied by the cellular phenotype plasticity and cell dormancy activation. In HNSCC cell lines, PRRX1 positively promoted the expression of known EMT inducers and cooperated with activated TGF-β1 to contribute to EMT and migration and invasion of HNSCC cells. Then, we found that overexpression of miR-642b-3p, one of the most significantly downregulated miRNAs in PRRX1-overexpressed cells, significantly reduced the migration and invasion, and increased cell proliferation and apoptosis. And miR-642b-3p restoration reversed PRRX1-induced cell dormancy and EMT of HNSCC cells through TGF-β2 and p38. Finally, we demonstrated that overexpressed PRRX1 was closely correlated with miR-642b-3p downregulation and the upregulation of TGF-β2 and p38 in a xenograft model of HNSCC. CONCLUSIONS: Our findings showed that PRRX1 may be one of the main driving forces for the cellular phenotype plasticity and tumor dormancy of HNSCC. Therefore, we can raise the possibility that EMT may help to keep cancer cell in dormant state and mesenchymal-epithelial transition may resurge dormancy in HNSCC.

Epithelial-to-mesenchymal transition status of primary breast carcinomas and its correlation with metastatic behavior

Background

Epithelial-to-mesenchymal transition (EMT) has been implicated as an important step in the development of distant metastases. We therefore wished to study EMT status of primary breast carcinomas from patients who during follow-up developed distant metastases.

Methods

mRNA expression profiles of primary breast carcinoma samples (n = 151) from patients who developed metastatic disease were analyzed and EMT status was designated using a previously described EMT-core signature. EMT status of the primary tumor was correlated to clinicopathological characteristics, molecular subtypes, metastasis pattern, chemotherapy response and survival outcomes. In addition, using immunohistochemistry, the expression levels of several proteins implicated in EMT were studied (CDH1, CDH2, NAT1, SNAI2, TWIST1, VIM, and ZEB1) compared with the designated EMT status and survival.

Results

Utilizing the 130-gene-EMT-core signature, 66.2% of the primary tumors in the current study was assessed as EMT-activated. In contrast to our expectations, analyses revealed that 84.6% of Luminal A tumors, 65.1% of Luminal B tumors, and 55.6% of HER2-like had an activated EMT status, compared to only 25% of the basal-type tumors (p < 0.001). EMT status was not correlated to the pattern of metastatic disease, metastasis-specific survival, and overall survival. Similarly, there was not a significant association between EMT status of the primary tumor and chemotherapy response in the metastatic setting. Immunostaining for NAT1 and TWIST1 correlated with the EMT status (p 0.003 and p 0.047, respectively). Multivariate analyses showed that NAT1 and TWIST1 staining was significantly associated with EMT status regardless of the estrogen receptor status of the tumors (p values: 0.020 and 0.027, respectively).

Conclusions

The EMT status of breast cancers, as defined by the presence of a core EMT gene expression signature is associated with non-basal-type tumors, but not with the pattern of distant metastasis. Of several potential immunohistochemical EMT markers, only NAT1 and TWIST1 expression levels were associated with the gene expression-based EMT status.

Electronic supplementary material

The online version of this article (10.1007/s10549-018-05089-5) contains supplementary material, which is available to authorized users.

Non-redundant functions of EMT transcription factors

Epithelial-mesenchymal transition (EMT) is a crucial embryonic programme that is executed by various EMT transcription factors (EMT-TFs) and is aberrantly activated in cancer and other diseases. However, the causal role of EMT and EMT-TFs in different disease processes, especially cancer and metastasis, continues to be debated. In this Review, we identify and describe specific, non-redundant functions of the different EMT-TFs and discuss the reasons that may underlie disputes about EMT in cancer.

Ping-Pong-Tumor and Host in Pancreatic Cancer Progression

Metastasis is the main cause of high pancreatic cancer (PaCa) mortality and trials dampening PaCa mortality rates are not satisfying. Tumor progression is driven by the crosstalk between tumor cells, predominantly cancer-initiating cells (CIC), and surrounding cells and tissues as well as distant organs, where tumor-derived extracellular vesicles (TEX) are of major importance. A strong stroma reaction, recruitment of immunosuppressive leukocytes, perineural invasion, and early spread toward the peritoneal cavity, liver, and lung are shared with several epithelial cell-derived cancer, but are most prominent in PaCa. Here, we report on the state of knowledge on the PaCIC markers Tspan8, alpha6beta4, CD44v6, CXCR4, LRP5/6, LRG5, claudin7, EpCAM, and CD133, which all, but at different steps, are engaged in the metastatic cascade, frequently via PaCIC-TEX. This includes the contribution of PaCIC markers to TEX biogenesis, targeting, and uptake. We then discuss PaCa-selective features, where feedback loops between stromal elements and tumor cells, including distorted transcription, signal transduction, and metabolic shifts, establish vicious circles. For the latter particularly pancreatic stellate cells (PSC) are responsible, furnishing PaCa to cope with poor angiogenesis-promoted hypoxia by metabolic shifts and direct nutrient transfer via vesicles. Furthermore, nerves including Schwann cells deliver a large range of tumor cell attracting factors and Schwann cells additionally support PaCa cell survival by signaling receptor binding. PSC, tumor-associated macrophages, and components of the dysplastic stroma contribute to perineural invasion with signaling pathway activation including the cholinergic system. Last, PaCa aggressiveness is strongly assisted by the immune system. Although rich in immune cells, only immunosuppressive cells and factors are recovered in proximity to tumor cells and hamper effector immune cells entering the tumor stroma. Besides a paucity of immunostimulatory factors and receptors, immunosuppressive cytokines, myeloid-derived suppressor cells, regulatory T-cells, and M2 macrophages as well as PSC actively inhibit effector cell activation. This accounts for NK cells of the non-adaptive and cytotoxic T-cells of the adaptive immune system. We anticipate further deciphering the molecular background of these recently unraveled intermingled phenomena may turn most lethal PaCa into a curatively treatable disease.

Heterogeneity and Plasticity of Breast Cancer Stem Cells

In the last 20 years, the conventional view of breast cancer as a homogeneous collection of highly proliferating malignant cells was totally replaced by a model of increased complexity, which points out that breast carcinomas are tissues composed of multiple populations of transformed cells. A large diversity of host cells and structural components of the extracellular matrix constitute the mammary tumour microenvironment, which supports its growth and progression, where individual cancer cells evolve with cumulative phenotypic and genetic heterogeneity. Moreover, contributing to this heterogeneity, it has been demonstrated that breast cancers can exhibit a hierarchical organization composed of tumour cells displaying divergent lineage biomarkers and where, at the apex of this hierarchy, some neoplastic cells are able to self-renew and to aberrantly differentiate. Breast cancer stem cells (BCSCs), as they were entitled, not only drive tumourigenesis, but also mediate metastasis and contribute to therapy resistance.Recently, adding more complexity to the system, it has been demonstrated that BCSCs maintain high levels of plasticity, being able to change between mesenchymal-like and epithelial-like states in a process regulated by the tumour microenvironment. These stem cell state transitions play a fundamental role in the process of tumour metastasis, as well as in the resistance to putative therapeutic strategies to target these cells. In this chapter, it will be mainly discussed the emerging knowledge regarding the contribution of BCSCs to tumour heterogeneity, their plasticity, and the role that this plasticity can play in the establishment of distant metastasis. A major focus will also be given to potential clinical implications of these discoveries in breast cancer recurrence and to possible BCSC targeted therapeutics by the use of specific biomarkers.

EMT Transition States during Tumor Progression and Metastasis

Epithelial-mesenchymal transition (EMT) is a process in which epithelial cells acquire mesenchymal features. In cancer, EMT is associated with tumor initiation, invasion, metastasis, and resistance to therapy. Recently, it has been demonstrated that EMT is not a binary process, but occurs through distinct cellular states. Here, we review the recent studies that demonstrate the existence of these different EMT states in cancer and the mechanisms regulating their functions. We discuss the different functional characteristics, such as proliferation, propagation, plasticity, invasion, and metastasis associated with the distinct EMT states. We summarize the role of the transcriptional and epigenetic landscapes, gene regulatory network and their surrounding niche in controlling the transition through the different EMT states.

Tspan8 and Tspan8/CD151 knockout mice unravel the contribution of tumor and host exosomes to tumor progression

BACKGROUND

The tetraspanins Tspan8 and CD151 promote metastasis, exosomes (Exo) being suggested to be important in the crosstalk between tumor and host. The contribution of Tspan8 and CD151 to host versus tumor-derived exosome (TEX) activities being not defined, we approached the questions using 3-methylcholanthrene-induced (MCA) tumors from wt, Tspan8ko, CD151ko and Tspan8/CD151 (db)ko mice, implanted into tetraspanin-competent and deficient hosts.

METHODS

Tumor growth and dissemination, hematopoiesis and angiogenesis were surveyed in wild type (wt), Tspan8ko, CD151ko and dbko mice bearing tetraspanin-competent and -deficient MCA tumors. In vitro studies using tumor cells, bone marrow cells (BMC) and endothelial cells (EC) elaborated the mechanism of serum (s)Exo- and TEX-induced target modulation.

RESULTS

Tumors grew in autochthonous and syngeneic hosts differing in Tspan8- and/or CD151-competence. However, Tspan8ko- and/or CD151ko-tumor cell dissemination and settlement in metastatic organs was significantly reduced in the autochthonous host, and less severely in the wt-host. Impaired wt-MCA tumor dissemination in the ko-host confirmed a contribution of host- and tumor-Tspan8/-CD151 to tumor cell dissemination, delivery of sExo and TEX being severely impaired by a Tspan8ko/CD151ko. Coculturing tumor cells, BMC and EC with sExo and TEX revealed minor defects in epithelial mesenchymal transition and apoptosis resistance of ko tumors. Strongly reduced migratory and invasive capacity of Tspan8ko/CD151ko-MCA relies on distorted associations with integrins and CAM and missing Tspan8/CD151-promoted recruitment of proteases. The defects, differing between Tspan8ko- and CD151ko-MCA, were rescued by wt-TEX and, less efficiently Tspan8ko- and CD151ko-TEX. Minor defects in hematopoietic progenitor maturation were based on the missing association of hematopoietic growth factors /- receptors with CD151 and, less pronounced, Tspan8. Rescue of impaired angiogenesis in ko mice by wt-sExo and promotion of angiogenesis by TEX depended on the association of Tspan8 and CD151 with GPCR and RTK in EC and tumor cells.

CONCLUSIONS

Tspan8-/CD151-TEX play central roles in tumor progression. Tspan8-/CD151-sExo and TEX contribute by stimulating angiogenesis. Tspan8 and CD151 fulfill these tasks by associating with function-relevant proteins, the additive impact of Tspan8 and CD151 relying on differences in preferred associations. The distinct Tspan8 and CD151 contributions suggest a blockade of TEX-Tspan8 and -CD151 promising for therapeutic intervention.

Tumor budding and adjacent tissue at the invasive front correlate with delayed neck metastasis in clinical early-stage tongue squamous cell carcinoma

Background and Objectives

Some patients with early‐stage oral cancer have a poor prognosis owing to the delayed neck metastasis (DNM). Tumor budding is reportedly a promising prognostic marker in many cancers. Moreover, the tissue surrounding a tumor is also considered to play a prognostic role. In this study, we evaluated whether tumor budding and adjacent tissue at the invasive front can be potential novel predictors of DNM in early tongue cancer.

Methods

In total, 337 patients with early‐stage tongue squamous cell carcinoma were retrospectively reviewed. The patient characteristics and histopathological factors were evaluated for association with DNM. DNM rates were calculated; items which were significant in the univariate analysis were used as explanatory variables, and independent factors for DNM were identified by the multivariate analysis.

Results

The univariate analysis identified T classification, depth of invasion, tumor budding, vascular invasion, and adjacent tissue at the invasive front as significant predictors of DNM; the multivariate analysis using these factors revealed all the above variables except vascular invasion, which are independent predictors of DNM.

Conclusion

In addition to conventional predictors, high grade tumor budding and adjacent tissue at the invasive front can serve as useful predictors of DNM in early tongue cancer.

Genetic dissection of the miR-200-Zeb1 axis reveals its importance in tumor differentiation and invasion

The epithelial-to-mesenchymal transition (EMT) is an important mechanism for cancer progression and metastasis. Numerous in vitro and tumor-profiling studies point to the miR-200-Zeb1 axis as crucial in regulating this process, yet in vivo studies involving its regulation within a physiological context are lacking. Here, we show that miR-200 ablation in the Rip-Tag2 insulinoma mouse model induces beta-cell dedifferentiation, initiates an EMT expression program, and promotes tumor invasion. Strikingly, disrupting the miR-200 sites of the endogenous Zeb1 locus causes a similar phenotype. Reexpressing members of the miR-200 superfamily in vitro reveals that the miR-200c family and not the co-expressed and closely related miR-141 family is responsible for regulation of Zeb1 and EMT. Our results thus show that disrupting the in vivo regulation of Zeb1 by miR-200c is sufficient to drive EMT, thus highlighting the importance of this axis in tumor progression and invasion and its potential as a therapeutic target.