ZEB1-responsive genes in non-small cell lung cancer

miR-200c-141 induces a hybrid E/M state and promotes collective cell migration in MDA-MB-231 cells

The microRNA-200 (miR-200) family is a potent suppressor of epithelial-to-mesenchymal transition (EMT). While its role as a tumor suppressor has been well documented, recent studies suggested that it can promote cancer progression in several stages. In this study, we investigated whether the miR-200 family members play a role in the acquisition of a hybrid epithelial/mesenchymal (E/M) state, which is reported to be associated with cancer malignancy, in mesenchymal MDA-MB-231 cells. Our results demonstrated that the induction of miR-200c-141, a cluster of the miR-200 family member, can induce the expression of epithelial gene and cell-cell junction while mesenchymal markers are retained. Moreover, induction of miR-200c-141 promoted collective migration accompanied by the formation of F-actin cables anchored by adherens junction. These results suggest that the miR-200 family can induce a hybrid E/M state and endows with the ability of collective cell migration in mesenchymal cancer cells.

Expression Profiling of EMT Transcriptional Regulators ZEB1 and ZEB2 in Different Histopathological Grades of Oral Squamous Cell Carcinoma Patients

Background

Pakistan has a high burden of oral cancers, with a prevalence rate of around 9%. Oral Squamous Cell Carcinoma (OSCC) accounts for about 90% of oral cancer cases. Epithelial to Mesenchymal Transition (EMT) gets highly stimulated in tumor cells by adopting subsequent malignant features of highly invasive cancer populations. Zinc Finger E-Box binding factors, ZEB1 and ZEB2, are regulatory proteins that promote EMT by suppressing the adherent ability of cells transforming into highly motile cancerous cells. The present study aimed to analyze the expression of EMT regulators, ZEB1 and ZEB2, and their association with the clinicopathological features in different grades of OSCC patients.

Methods

Tissue samples were collected for both case and control groups from the recruited study participants. Cancer tissues (cases) were collected from the confirmed OSCC patients, and healthy tissues (controls) were collected from third-molar dental extraction patients. The study participants were recruited with informed consent and brief demographic and clinical characteristics. The case group was further segregated with respect to the histological cancer grading system into well-differentiated (WD), moderately differentiated (MD), and poorly differentiated (PD) squamous cell carcinoma (SCC) groups. RNA was extracted from the tissue samples for expression profiling of ZEB1 and ZEB2 genes through quantitative real-time PCR (qRT-PCR).

Results

All of the recruited participants had a mean age of 46.55 ± 11.7 (years), with most of them belonging to Urdu speaking ethnic group and were married. The BMI (kg/m2) of the healthy participants was in the normal range (18-22 kg/m2). However, BMI was found to be reduced with the proliferation in the pathological state of cancer. The oral hygiene of patients was better than the healthy participants, possibly due to the strict oral hygiene practice concerns of consultants. Every recruited OSCC patient had one or multiple addiction habits for more than a year. Patients reported health frailty (46.6%), unhealed mouth sores (40%), swallowing difficulties and white/reddish marks (80%), and restricted mouth opening (64.4%). Furthermore, 82.2% of the recruited patients observed symptoms within 1-12 months, and buccal mucosa was the most exposed tumor site among 55.6% of the patients. Expression profiling of EMT regulators showed gradual over-expressions of ZEB1 (8, 20, and 42 folds) and ZEB2 (4, 10, and 18 folds) in respective histological cancer grades.

Conclusion

High expressions of ZEBs have been significantly associated with cancer progression and poor health. However, no association was found between OSCC with other clinicopathological features when compared to healthy controls.

FGFR-targeted therapeutics: clinical activity, mechanisms of resistance and new directions

Fibroblast growth factor (FGF) signalling via FGF receptors (FGFR1-4) orchestrates fetal development and contributes to tissue and whole-body homeostasis, but can also promote tumorigenesis. Various agents, including pan-FGFR inhibitors (erdafitinib and futibatinib), FGFR1/2/3 inhibitors (infigratinib and pemigatinib), as well as a range of more-specific agents, have been developed and several have entered clinical use. Erdafitinib is approved for patients with urothelial carcinoma harbouring FGFR2/3 alterations, and futibatinib and pemigatinib are approved for patients with cholangiocarcinoma harbouring FGFR2 fusions and/or rearrangements. Clinical benefit from these agents is in part limited by hyperphosphataemia owing to off-target inhibition of FGFR1 as well as the emergence of resistance mutations in FGFR genes, activation of bypass signalling pathways, concurrent TP53 alterations and possibly epithelial-mesenchymal transition-related isoform switching. The next generation of small-molecule inhibitors, such as lirafugratinib and LOXO-435, and the FGFR2-specific antibody bemarituzumab are expected to have a reduced risk of hyperphosphataemia and the ability to overcome certain resistance mutations. In this Review, we describe the development and current clinical role of FGFR inhibitors and provide perspective on future research directions including expansion of the therapeutic indications for use of FGFR inhibitors, combination of these agents with immune-checkpoint inhibitors and the application of novel technologies, such as artificial intelligence.

Loss of ESRP2 Activates TAK1-MAPK Signaling through the Fetal RNA-Splicing Program to Promote Hepatocellular Carcinoma Progression

Tumors usually display fetal-like characteristics, and many oncofetal proteins have been identified. However, fetal-like reprogramming of RNA splicing in hepatocellular carcinoma (HCC) is poorly understood. Here, it is demonstrated that the expression of epithelial splicing regulatory protein 2 (ESRP2), an RNA splicing factor, is suppressed in fetal hepatocytes and HCC, in parallel with tumor progression. By combining RNA-Seq with splicing analysis, it is identified that ESRP2 controls the fetal-to-adult switch of multiple splice isoforms in HCC. Functionally, ESRP2 suppressed cell proliferation and migration by specifically switching the alternative splicing (AS) of the TAK1 gene and restraining the expression of the fetal and oncogenic isoform, TAK1_ΔE12. Notably, aberrant TAK1 splicing led to the activation of p38MAPK signaling and predicted poor prognosis in HCC patients. Further investigation revealed that TAK1_ΔE12 protein interacted closely with TAB3 and formed liquid condensation in HCC cells, resulting in p38MAPK activation, enhanced cell migration, and accelerated tumorigenesis. Loss of ESRP2 sensitized HCC cells to TAK1 kinase inhibitor (TAK1i), promoting pyroptotic cell death and CD8+ T cell infiltration. Combining TAK1i with immune checkpoint therapy achieved potent tumor regression in mice. Overall, the findings reveal a previously unexplored onco-fetal reprogramming of RNA splicing and provide novel therapeutic avenues for HCC.

Oncoviruses: Induction of cancer development and metastasis by increasing anoikis resistance

The phenomenon of cell death is a vital aspect in the regulation of aberrant cells such as cancer cells. Anoikis is a kind of cell death that occurs when cells get separated from the extracellular matrix. Some cancer cells can inhibit anoikis in order to progress metastasis. One of the key variables that might be implicated in anoikis resistance (AR) is viral infections. The most important viruses involved in this process are Epstein-Barr virus, human papillomavirus, hepatitis B virus, human herpes virus 8, human T-cell lymphotropic virus type 1, and hepatitis C virus. A better understanding of how carcinogenic viruses suppress anoikis might be helpful in developing an effective treatment for virus-associated cancers. In the current study, we review the role of the mentioned viruses and their gene products in anoikis inhibition.

ZEB1 Is Regulated by K811 Acetylation to Promote Stability, NuRD Complex Interactions, EMT, and NSCLC Metastasis

Epithelial-to-mesenchymal transition results in loss of specialized epithelial cell contacts and acquisition of mesenchymal invasive capacity. The transcription repressor zinc finger E-box-binding homeobox 1 (ZEB1) binds to E-boxes of gene promoter regions to suppress the expression of epithelial genes. ZEB1 has inconsistent molecular weights, which have been attributed to posttranslational modifications (PTM). We performed mass spectrometry and identified K811 acetylation as a novel PTM in ZEB1. To define the role of ZEB1 acetylation in regulating function, we generated ZEB1 acetyl-mimetic (K811Q) and acetyl-deficient (K811R) mutant-expressing non-small cell lung cancer cell lines (NSCLC). We demonstrate that the K811R ZEB1 (125 kDa) has a shorter protein half-life than wild-type (WT) ZEB1 and K811Q ZEB1 (∼225 kDa), suggesting that lack of ZEB1 acetylation in the lower molecular weight form affects protein stability. Further, the acetylated form of ZEB1 recruits the nucleosome remodeling and deacetylase (NuRD) complex to bind the promoter of its target genes mir200c-141 and SEMA3F. RNA-sequencing revealed that WT ZEB1 and K811Q ZEB1 downregulate the expression of epithelial genes to promote lung adenocarcinoma invasion and metastasis, whereas the K811R ZEB1 does not. Our findings establish that the K811 acetylation promotes ZEB1 protein stability, interaction with other protein complexes, and subsequent invasion/metastasis of lung adenocarcinoma via epithelial-to-mesenchymal transition.

IMPLICATIONS

The molecular mechanisms by which ZEB1 is regulated by K811 acetylation to promote protein stability, NuRD complex and promoter interactions, and function are relevant to the development of treatment strategies to prevent and treat metastasis in patients with NSCLC.

Transcriptional dynamics of delaminating neuroblasts in the mouse otic vesicle

An abundance of research has recently highlighted the susceptibility of cochleovestibular ganglion (CVG) neurons to noise damage and aging in the adult cochlea, resulting in hearing deficits. Furthering our understanding of the transcriptional cascades that contribute to CVG development may provide insight into how these cells can be regenerated to treat inner ear dysfunction. Here we perform a high-depth single-cell RNA sequencing analysis of the E10.5 otic vesicle and its surrounding tissues, including CVG precursor neuroblasts and emerging CVG neurons. Clustering and trajectory analysis of otic-lineage cells reveals otic markers and the changes in gene expression that occur from neuroblast delamination toward the development of the CVG. This dataset provides a valuable resource for further identifying the mechanisms associated with CVG development from neurosensory competent cells within the otic vesicle.

Aberrant expression of UBE2C in endometrial cancer and its correlation to epithelial mesenchymal transition

Ubiquitin-conjugating enzyme E2C (UBE2C), its overexpression promotes tumor progression, is a key component of the ubiquitin conjugating proteasome complex. Epithelial-mesenchymal transition, which is lost epithelial features and gained mesenchymal features in some epithelial cancers, is involved in epithelial cancers' invasiveness and metastasis. The aim of this study is to detect the expression of UBE2C, WNT5α, and E-cad in endometrial cancer (EC) and their clinical significance. The expression of UBE2C, WNT5α, and ZEB1 in 125 cases EC tissues were detected by immunohistochemistry. Patients clinicopathological, demography, and follow-up data were also collected. Positive rates of expression of UBE2C and ZEB1 were significantly higher in EC tissues when compared with the control tissues. The positive expression of UBE2C and ZEB1 were positively associated with tumor stages, local lymph node metastasis, and International Federation of Gynecology and Obstetrics (FIGO) stages. The positive rate of expression of WNT5a was significantly lower in EC tissues when compared with the control tissues. And positive expression of E-cad was inversely related to tumor stages, lymph node metastasis stages, and FIGO stages. Kaplan-Meier analyses demonstrated that positive expression of UBE2C or ZEB1 for EC patients had unfavorably overall survival time when compared with patients with negative expression of UBE2C or ZEB1. And EC patients with positive expression of WNT5a had favorably overall survival time when compared with EC patients with negative expression of WNT5a. Multivariate analysis demonstrated that positive expression UBE2C, WNT5α, and ZEB1, as well as FIGO stages were independent prognostic factors for EC patients. UBE2C, ZEB1, and WNT5a should be considered promising biomarkers for EC patients' prognosis.

Cytosolic EpCAM cooperates with H-Ras to regulate epithelial to mesenchymal transition through ZEB1

Next generation sequencing of human cancer mutations has identified novel therapeutic targets. Activating Ras oncogene mutations play a central role in oncogenesis, and Ras-driven tumorigenesis upregulates an array of genes and signaling cascades that can transform normal cells into tumor cells. In this study, we investigated the role of altered localization of epithelial cell adhesion molecule (EpCAM) in Ras-expressing cells. Analysis of microarray data demonstrated that Ras expression induced EpCAM expression in normal breast epithelial cells. Fluorescent and confocal microscopy showed that H-Ras mediated transformation also promoted epithelial-to-mesenchymal transition (EMT) together with EpCAM. To consistently localize EpCAM in the cytosol, we generated a cancer-associated EpCAM mutant (EpCAM-L240A) that is retained in the cytosol compartment. Normal MCF-10A cells were transduced with H-Ras together with EpCAM wild-type (WT) or EpCAM-L240A. WT-EpCAM marginally effected invasion, proliferation, and soft agar growth. EpCAM-L240A, however, markedly altered cells and transformed to mesenchymal phenotype. Ras-EpCAM-L240A expression also promoted expression of EMT factors FRA1, ZEB1 with inflammatory cytokines IL-6, IL-8, and IL1. This altered morphology was reversed using MEK-specific inhibitors and to some extent JNK inhibition. Furthermore, these transformed cells were sensitized to apoptosis using paclitaxel and quercetin, but not other therapies. For the first time, we have demonstrated that EpCAM mutations can cooperate with H-Ras and promote EMT. Collectively, our results highlight future therapeutic opportunities in EpCAM and Ras mutated cancers.

A novel Chr1-miR-200 driven whole transcriptome signature shapes tumor immune microenvironment and predicts relapse in early-stage lung adenocarcinoma

BACKGROUND

In Lung adenocarcinoma (LUAD), targeted therapies and immunotherapies have moved from metastatic to early stage and stratification of the relapse risk becomes mandatory. Here we identified a miR-200 based RNA signature that delineates Epithelial-to-mesenchymal transition (EMT) heterogeneity and predicts survival beyond current classification systems.

METHODS

A miR-200 signature was identified using RNA sequencing. We scored the miR-200 signature by WISP (Weighted In Silico Pathology), used GSEA to identify pathway enrichments and MCP-counter to characterize immune cell infiltrates. We evaluate the clinical value of this signature in our series of LUAD and using TCGA and 7 published datasets.

RESULTS

We identified 3 clusters based on supervised classification: I is miR-200-sign-down and enriched in TP53 mutations IIA and IIB are miR-200-sign-up: IIA is enriched in EGFR (p < 0.001), IIB is enriched in KRAS mutation (p < 0.001). WISP stratified patients into miR-200-sign-down (n = 65) and miR-200-sign-up (n = 42). Several biological processes were enriched in MiR-200-sign-down tumors, focal adhesion, actin cytoskeleton, cytokine/receptor interaction, TP53 signaling and cell cycle pathways. Fibroblast, immune cell infiltration and PDL1 expression were also significantly higher suggesting immune exhaustion. This signature stratified patients into high-vs low-risk groups, miR-200-sign-up had higher DFS, median not reached at 60 vs 41 months and within subpopulations with stage I, IA, IB, or II. Results were validated on TCGA data on 7 public datasets.

CONCLUSION

This EMT and miR-200-related prognostic signature refines prognosis evaluation independently of tumor stage and paves the way towards assessing the predictive value of this LUAD clustering to optimize perioperative treatment.

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

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

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

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

Prognostic impact of tumor microenvironment-related markers in patients with adenocarcinoma of the lung

Cancer-associated fibroblasts (CAFs) are a prominent component in the tumor microenvironment (TME), which plays an important role in lung carcinogenesis. Here, we investigated microenvironmental markers expressed by CAFs, including α-smooth muscle actin, CD10, podoplanin, fibroblast-specific protein 1, platelet-derived growth factor α and β, fibroblast-associated protein, tenascin-C, zinc finger E-box binding homeobox 1 (ZEB1), and twist-related protein 1 expression levels. We evaluated samples from 257 patients with lung adenocarcinoma (LAD) to assess the associations of CAF-related protein expression patterns with prognosis. LAD cases were stratified using cluster analysis. To determine the utility of prognostic markers in LAD, univariate and multivariate analyses were performed. LAD cases were classified into subgroups 1 and 2. Subgroup 2 was shown to be significantly correlated with disease-free and overall survival using univariate and multivariate analyses in this group. Upregulation of podoplanin was identified as a single prognostic marker in this study by univariate and multivariate analyses. In addition, ZEB1 overexpression was correlated with disease-free survival. Our current results suggested that the specific CAF phenotype (e.g., the expression pattern of CAF-related proteins) could predict outcomes in patients with LAD. In addition, podoplanin upregulation may predict outcomes in these patients.

Underlying mechanisms of epithelial splicing regulatory proteins in cancer progression

Cancer is the second-leading disease-related cause of global mortality after cardiovascular disease. Despite significant advances in cancer therapeutic strategies, cancer remains one of the major obstacles to human life extension. Cancer pathogenesis is extremely complicated and not fully understood. Epithelial splicing regulatory proteins (ESRPs), including ESRP1 and ESRP2, belong to the heterogeneous nuclear ribonucleoprotein family of RNA-binding proteins and are crucial regulators of the alternative splicing of messenger RNAs (mRNAs). The expression and activity of ESRPs are modulated by various mechanisms, including post-translational modifications and non-coding RNAs. Although a growing body of evidence suggests that ESRP dysregulation is closely associated with cancer progression, the detailed mechanisms remain inconclusive. In this review, we summarize recent findings on the structures, functions, and regulatory mechanisms of ESRPs and focus on their underlying mechanisms in cancer progression. We also highlight the clinical implications of ESRPs as prognostic biomarkers and therapeutic targets in cancer treatment. The information reviewed herein could be extremely beneficial to the development of individualized therapeutic strategies for cancer patients.

The EMT-activator ZEB1 is unrelated to platinum drug resistance in ovarian cancer but is predictive of survival

The IGROVCDDP cisplatin-resistant ovarian cancer cell line is an unusual model, as it is also cross-resistant to paclitaxel. IGROVCDDP, therefore, models the resistance phenotype of serous ovarian cancer patients who have failed frontline platinum/taxane chemotherapy. IGROVCDDP has also undergone epithelial-mesenchymal transition (EMT). We aim to determine if alterations in EMT-related genes are related to or independent from the drug-resistance phenotypes. EMT gene and protein markers, invasion, motility and morphology were investigated in IGROVCDDP and its parent drug-sensitive cell line IGROV-1. ZEB1 was investigated by qPCR, Western blotting and siRNA knockdown. ZEB1 was also investigated in publicly available ovarian cancer gene-expression datasets. IGROVCDDP cells have decreased protein levels of epithelial marker E-cadherin (6.18-fold, p = 1.58e-04) and higher levels of mesenchymal markers vimentin (2.47-fold, p = 4.43e-03), N-cadherin (4.35-fold, p = 4.76e-03) and ZEB1 (3.43-fold, p = 0.04). IGROVCDDP have a spindle-like morphology consistent with EMT. Knockdown of ZEB1 in IGROVCDDP does not lead to cisplatin sensitivity but shows a reversal of EMT-gene signalling and an increase in cell circularity. High ZEB1 gene expression (HR = 1.31, n = 2051, p = 1.31e-05) is a marker of poor overall survival in high-grade serous ovarian-cancer patients. In contrast, ZEB1 is not predictive of overall survival in high-grade serous ovarian-cancer patients known to be treated with platinum chemotherapy. The increased expression of ZEB1 in IGROVCDDP appears to be independent of the drug-resistance phenotypes. ZEB1 has the potential to be used as biomarker of overall prognosis in ovarian-cancer patients but not of platinum/taxane chemoresistance.

Resistance to mutant KRASV12-induced senescence in a hTERT/Cdk4-immortalized normal human bronchial epithelial cell line

Mutant KRAS, the most frequently occurring (∼30%) driver oncogene in lung adenocarcinoma, induces normal epithelial cells to undergo senescence. This phenomenon, called "oncogene-induced senescence (OIS)", prevents mutant KRAS-induced malignant transformation. We have previously reported that mutant KRAS^V12 induces OIS in a subset of normal human bronchial epithelial cell line immortalized with hTERT and Cdk4. Understanding the mechanism and efficacy of this important cancer prevention mechanism is a key knowledge gap. Therefore, this study investigates mutant KRAS^V12-induced OIS in upregulated telomerase combined with the p16/RB pathway inactivation in normal bronchial epithelial cells. The normal (non-transformed and non-tumorigenic) human bronchial epithelial cell line HBEC3 (also called "HBEC3KT"), immortalized with hTERT ("T") and Cdk4 ("K"), was used in this study. HBEC3 that expressed mutant KRAS^V12 in a doxycycline-regulated manner was established (designated as HBEC3-RIN2). Controlled induction of mutant KRAS^V12 expression induced partial epithelial-to-mesenchymal transition in HBEC3-RIN2 cells, which was associated with upregulated expression of ZEB1 and SNAIL. Mutant KRAS^V12 caused the majority of HBEC3-RIN2 to undergo morphological changes; suggestive of senescence, which was associated with enhanced autophagic flux, evaluated by LC-3 Western blot and CYTO-ID, an autophagosome-specific staining kit. Upon mutant KRAS^V12 expression, only a small HBEC3-RIN2 cell subset underwent senescence, as shown by a senescence-associated β-galactosidase staining (SA-βG) method. Furthermore, mutant KRAS^V12 enhanced cell growth, evaluated by colorimetric proliferation assay, and liquid and soft agar colony formation assays, partially through increased phosphorylated AKT and ERK expression but did not affect cell division, or cell cycle status. Intriguingly, mutant KRAS^V12 reduced p53 protein expression but increased p21 protein expression by prolonging its half-life. These results indicate that a hTERT/Cdk4 -immortalized normal bronchial epithelial cell line is partially resistant to mutant KRAS^V12-induced senescence. This suggests that OIS does not efficiently suppress KRAS^V12-induced transformation in the context of the simultaneous occurrence of telomerase upregulation and inactivation of the p16/Rb pathway.

USP18 promotes tumor metastasis in esophageal squamous cell carcinomas via deubiquitinating ZEB1

The dysregulation of deubiquitinating enzymes (DUBs), which regulate the stability of most cellular proteins, have been implicated in many human diseases, including cancers. Ubiquitin-specific protease 18 (USP18), a member of the DUBs family, functions as a potential tumour promoter in various cancers. However, the biological function and clinical significance of USP18 in esophageal squamous cell carcinomas (ESCC) are still unclear. Here, we found that ESCC tumors had higher USP18 expression compared with that of normal esophageal epithelial tissues, and high USP18 level was significantly correlated with malignant phenotype and shorter survival in patients with ESCC. In functional experiments, USP18 knockdown significantly inhibited ESCC invasion and metastasis in vitro. Consistently, a xenograft assay showed that knockdown of USP18 in ESCC cell suppressed their dissemination to lung tissue in vivo. Furthermore, we showed that USP18 promoted ESCC cell metastasis by inducing ZEB1 mediated epithelial-mesenchymal transition (EMT). Importantly, our results demonstrated that the oncogenic effect of USP18 in ESCC is partially dependent on ZEB1 enhancement. Mechanistic investigations revealed that USP18 directly bound ZEB1 and decreased its ubiquitination to enhance the protein stability of ZEB1 in ESCC cells. Overall, our data highlighted an essential role of USP18 in ESCC metastasis, suggesting that it could be a potential diagnostic and therapeutic target for ESCC.

Clinical assessment of the miR-34, miR-200, ZEB1 and SNAIL EMT regulation hub underlines the differential prognostic value of EMT miRs to drive mesenchymal transition and prognosis in resected NSCLC

BACKGROUND

Patients with non-small cell lung cancer (NSCLC) receiving curative surgery have a risk of relapse, and adjuvant treatments only translate into a 5% increase in 5-year survival. We assessed the clinical significance of epithelial-mesenchymal transition (EMT) and explored its association with the [SNAIL/miR-34]:[ZEB/miR-200] regulation hub to refine prognostic information.

METHODS

We validated a 7-gene EMT score using a consecutive series of 176 resected NSCLC. We quantified EMT transcription factors, microRNAs (miRs) of the miR-200, miR-34 families and miR-200 promoter hypermethylation to identify outcome predictors.

RESULTS

Most tumours presented with an EMT-hybrid state and the EMT score was not predictive of outcome. Individually, all miR-200 were inversely associated with the EMT score, but only chromosome-1 miRs, miR-200a, b, 429, were associated with disease-free survival (p = 0.08, 0.05 and 0.025) and overall survival (p = 0.013, 0.003 and 0.006). We validated these associations on The Cancer Genome Atlas data. Tumour unsupervised clustering based on miR expression identified two good prognostic groups, unrelated to the EMT score, suggesting that miR profiling may have an important clinical value.

CONCLUSION

miR-200 family members do not have similar predictive value. Core EMT-miR, regulators and not EMT itself, identify NSCLC patients with a low risk of relapse after surgery.

The RNA-Binding Protein ESRP1 Modulates the Expression of RAC1b in Colorectal Cancer Cells

Simple Summary

Colorectal cancer (CRC) ranks third for incidence and second for number of deaths among cancer types worldwide. Poor patient survival due to inadequate response to currently available treatment regimens points to the urgent requirement for personalized therapy in CRC patients. Our aim was to provide mechanistic insights into the pro-tumorigenic role of the RNA-binding protein ESRP1, which is highly expressed in a subset of CRC patients. We show that, in CRC cells, ESRP1 binds to and has the same trend in expression as RAC1b, a well-known tumor promoter. Thus, RAC1b may be a potential therapeutic target in ESRP1-overexpressing CRC.

Abstract

RNA binding proteins are well recognized as critical regulators of tumorigenic processes through their capacity to modulate RNA biogenesis, including alternative splicing, RNA stability and mRNA translation. The RNA binding protein Epithelial Splicing Regulatory Protein 1 (ESRP1) can act as a tumor suppressor or promoter in a cell type- and disease context-dependent manner. We have previously shown that elevated expression of ESRP1 in colorectal cancer cells can drive tumor progression. To gain further insights into the pro-tumorigenic mechanism of action of ESRP1, we performed cDNA microarray analysis on two colorectal cells lines modulated for ESRP1 expression. Intriguingly, RAC1b was highly expressed, both at mRNA and protein levels, in ESRP1-overexpressing cells, while the opposite trend was observed in ESRP1-silenced CRC cells. Moreover, RAC1 and RAC1b mRNA co-immunoprecipitate with ESRP1 protein. Silencing of RAC1b expression significantly reduced the number of soft agar colonies formed by ESRP1-overexpressing cells, suggesting that ESRP1 acted, at least partially, through RAC1b in its tumor-promoting activities in CRC cells. Thus, our data provide molecular cues on targetable candidates in CRC cases with high ESRP1 expression.

E2F1 and epigenetic modifiers orchestrate breast cancer progression by regulating oxygen-dependent ESRP1 expression

Epithelial splicing regulatory protein 1 (ESRP1) is an RNA binding protein that governs the alternative splicing events related to epithelial phenotypes. ESRP1 contributes significantly at different stages of cancer progression. ESRP1 expression is substantially elevated in carcinoma in situ compared to the normal epithelium, whereas it is drastically ablated in cancer cells within hypoxic niches, which promotes epithelial to mesenchymal transition (EMT). Although a considerable body of research sought to understand the EMT-associated ESRP1 downregulation, the regulatory mechanisms underlying ESRP1 upregulation in primary tumors remained largely uncharted. This study seeks to unveil the regulatory mechanisms that spatiotemporally fine-tune the ESRP1 expression during breast carcinogenesis. Our results reveal that an elevated expression of transcription factor E2F1 and increased CpG hydroxymethylation of the E2F1 binding motif conjointly induce ESRP1 expression in breast carcinoma. However, E2F1 fails to upregulate ESRP1 despite its abundance in oxygen-deprived breast cancer cells. Mechanistically, impelled by the hypoxia-driven reduction of tet methylcytosine dioxygenase 3 (TET3) activity, CpG sites across the E2F1 binding motif lose the hydroxymethylation marks while gaining the de novo methyltransferase-elicited methylation marks. These two oxygen-sensitive epigenetic events work in concert to repel E2F1 from the ESRP1 promoter, thereby diminishing ESRP1 expression under hypoxia. Furthermore, E2F1 skews the cancer spliceome by upregulating splicing factor SRSF7 in hypoxic breast cancer cells. Our findings provide previously unreported mechanistic insights into the plastic nature of ESRP1 expression and insinuate important implications in therapeutics targeting breast cancer progression.

Functional Implications of the Dynamic Regulation of EpCAM during Epithelial-to-Mesenchymal Transition

Epithelial cell adhesion molecule (EpCAM) is a transmembrane glycoprotein expressed in epithelial tissues. EpCAM forms intercellular, homophilic adhesions, modulates epithelial junctional protein complex formation, and promotes epithelial tissue homeostasis. EpCAM is a target of molecular therapies and plays a prominent role in tumor biology. In this review, we focus on the dynamic regulation of EpCAM expression during epithelial-to-mesenchymal transition (EMT) and the functional implications of EpCAM expression on the regulation of EMT. EpCAM is frequently and highly expressed in epithelial cancers, while silenced in mesenchymal cancers. During EMT, EpCAM expression is downregulated by extracellular signal-regulated kinases (ERK) and EMT transcription factors, as well as by regulated intramembrane proteolysis (RIP). The functional impact of EpCAM expression on tumor biology is frequently dependent on the cancer type and predominant oncogenic signaling pathways, suggesting that the role of EpCAM in tumor biology and EMT is multifunctional. Membrane EpCAM is cleaved in cancers and its intracellular domain (EpICD) is transported into the nucleus and binds β-catenin, FHL2, and LEF1. This stimulates gene transcription that promotes growth, cancer stem cell properties, and EMT. EpCAM is also regulated by epidermal growth factor receptor (EGFR) signaling and the EpCAM ectoderm (EpEX) is an EGFR ligand that affects EMT. EpCAM is expressed on circulating tumor and cancer stem cells undergoing EMT and modulates metastases and cancer treatment responses. Future research exploring EpCAM’s role in EMT may reveal additional therapeutic opportunities.

Whole-Genome Methylation Study of Congenital Lung Malformations in Children

Background and Objectives

The treatment of asymptomatic patients with congenital pulmonary malformations (CPMs) remains controversial, partially because the relationship between congenital lung malformations and malignancy is still undefined. Change in methylation pattern is a crucial event in human cancer, including lung cancer. We therefore studied all differentially methylated regions (DMRs) in a series of CPMs in an attempt to find methylation anomalies in genes already described in association with malignancy.

Methods

The DNA extracted from resected congenital lung malformations and control lung tissue was screened using Illumina MethylationEPIC arrays. Comparisons between the group of malformed samples or the malformed samples of same histology or each malformed sample and the controls and between a pleuropulmonary blastoma (PPB) and controls were performed. Moreover, each malformed sample was pairwise compared with its respective control. All differentially methylated regions (DMRs) with an adjusted p-value <0,05 were studied.

Results

Every comparison highlighted a number of DMRs closed to genes involved either in cell proliferation or in embryonic development or included in the Cancer Gene Census. Their abnormal methylation had been already described in lung tumors.

Conclusions

Methylation anomalies already described in lung tumors and also shared by the PPB were found in congenital lung malformations, regardless the histology. The presence of methylation abnormalities is suggestive of a correlation between congenital lung malformations and some step of malignant transformation.

Overview of Evidence-Based Chemotherapy for Oral Cancer: Focus on Drug Resistance Related to the Epithelial-Mesenchymal Transition

The increasing incidence of resistance to chemotherapeutic agents has become a major issue in the treatment of oral cancer (OC). Epithelial-mesenchymal transition (EMT) has attracted a great deal of attention in recent years with regard to its relation to the mechanism of chemotherapy drug resistance. EMT-activating transcription factors (EMT-ATFs), such as Snail, TWIST, and ZEB, can activate several different molecular pathways, e.g., PI3K/AKT, NF-κB, and TGF-β. In contrast, the activated oncological signal pathways provide reciprocal feedback that affects the expression of EMT-ATFs, resulting in a peritumoral extracellular environment conducive to cancer cell survival and evasion of the immune system, leading to resistance to multiple chemotherapeutic agents. We present an overview of evidence-based chemotherapy for OC treatment based on the National Comprehensive Cancer Network (NCCN) Chemotherapy Order Templates. We focus on the molecular pathways involved in drug resistance related to the EMT and highlight the signal pathways and transcription factors that may be important for EMT-regulated drug resistance. Rapid progress in antitumor regimens, together with the application of powerful techniques such as high-throughput screening and microRNA technology, will facilitate the development of therapeutic strategies to augment chemotherapy.

Low PRRX1 expression and high ZEB1 expression are significantly correlated with epithelial-mesenchymal transition and tumor angiogenesis in non-small cell lung cancer

BACKGROUND

Paired related homeobox 1 (PRRX1) and zinc finger E-box binding homeobox 1 (ZEB1) have been observed to play a vital role in the epithelial-mesenchymal transition (EMT) process in different types of cancer. The microvessel density (MVD) is the most common indicator used to quantify angiogenesis. This study aimed to investigate expression of PRRX1 and ZEB1 in non-small cell lung cancer (NSCLC) and to explore associations between these factors and tumor prognosis, EMT markers and angiogenesis.

METHODS

Data for a total of 111 surgically resected NSCLC cases from January 2013 to December 2014 were collected. We used an immunohistochemical method to detect expression levels of PRRX1, ZEB1, and E-cadherin, and to assess MVD (marked by CD34 staining). SPSS 26.0 was employed to evaluate the connection between these factors and clinical and histopathological features, overall survival (OS) and tumor angiogenesis.

RESULTS

PRRX1 expression was obviously lower in tumor samples than in control samples. Low expression of PRRX1, which was more common in the high-MVD group than in the low-MVD group (P = .009), correlated positively with E-cadherin expression (P < .001). Additionally, we showed that ZEB1 was expressed at higher levels in tumor samples than in normal samples. High expression of ZEB1 was associated negatively with E-cadherin expression (P < .001) and positively associated with high MVD (P = .001). Based on Kaplan-Meier and multivariate survival analyses, we found that PRRX1, ZEB1, E-cadherin and the MVD had predictive value for OS in NSCLC patients.

CONCLUSIONS

These findings suggest that PRRX1 and ZEB1 may serve as novel prognostic biomarkers and potential therapeutic targets.

Phospholipid dynamics in ex vivo lung cancer and normal lung explants

In cancer cells, metabolic pathways are reprogrammed to promote cell proliferation and growth. While the rewiring of central biosynthetic pathways is being extensively studied, the dynamics of phospholipids in cancer cells are still poorly understood. In our study, we sought to evaluate de novo biosynthesis of glycerophospholipids (GPLs) in ex vivo lung cancer explants and corresponding normal lung tissue from six patients by utilizing a stable isotopic labeling approach. Incorporation of fully ¹³C-labeled glucose into the backbone of phosphatidylethanolamine (PE), phosphatidylcholine (PC), and phosphatidylinositol (PI) was analyzed by liquid chromatography/mass spectrometry. Lung cancer tissue showed significantly elevated isotopic enrichment within the glycerol backbone of PE, normalized to its incorporation into PI, compared to that in normal lung tissue; however, the size of the PE pool normalized to the size of the PI pool was smaller in tumor tissue. These findings indicate enhanced PE turnover in lung cancer tissue. Elevated biosynthesis of PE in lung cancer tissue was supported by enhanced expression of the PE biosynthesis genes ETNK2 and EPT1 and decreased expression of the PC and PI biosynthesis genes CHPT1 and CDS2, respectively, in different subtypes of lung cancer in publicly available datasets. Our study demonstrates that incorporation of glucose-derived carbons into the glycerol backbone of GPLs can be monitored to study phospholipid dynamics in tumor explants and shows that PE turnover is elevated in lung cancer tissue compared to normal lung tissue.

PHRF1 promotes migration and invasion by modulating ZEB1 expression

PHRF1 (PHD and RING finger domain-containing protein 1) suppresses acute promyelocytic leukemia (APL) by promoting TGIF (TG-interacting factor) ubiquitination, while the PML-RARα protein interferes with PHRF1-mediated TGIF breakdown to facilitate APL. Beyond its role in APL tumorigenesis, PHRF1 contributes to non-homologous end-joining by linking H3K36 methylation and Nbs1 upon DNA damage insults. However, little is known regarding its function in tumor invasion. Here we highlight the unreported details of PHRF1 in the invasion of lung cancer cells by modulating the transcriptional level of ZEB1, a prominent regulator involved in epithelial-mesenchymal transition. PHRF1 associated with the phosphorylated C-terminal repeat domain of Rpb1, the large subunit of RNA polymerase II, through its C-terminal Set2 Rpb1 Interacting (SRI) domain. Chromatin immunoprecipitation revealed that PHRF1 bound to the proximal region adjacent to the transcription start site of ZEB1. SRI-deleted PHRF1 neither associated with Rpb1 nor increased ZEB1’s expression. Collectively, PHRF1 might take the stage at migration and invasion by modulating the expression of ZEB1.

Down-Regulation of ZEB1 by miR-199a-3p Overexpression Restrains Tumor Stem-Like Properties and Mitochondrial Function of Non-Small Cell Lung Cancer

Objective

MicroRNA-199a-3p (miR-199a-3p or miR-199b-3p) targeting of 3ʹ-UTR of ZEB1 was characterized as an important way to inhibit invasion and metastases in non-small cell lung cancer (NSCLC), one of the most common cancers around the world. Here we aimed to investigate the tumor-suppressive role of miR-199a-3p targeted ZEB1.

Materials and Methods

A549 cells were transfected with ZEB1 and/or miR-199a-3p. Then, tumor growth was investigated in xenograft mice. Stem-like property, proliferation and mitochondria injury were further validated in vitro.

Results

Overexpression of miR-199a-3p with premiRNAs significantly reduced tumor growth inhibited CD44 and Ki67 and increased Caspase-3 in A549 xenograft mice. Sphere formation and protein expression of stem-like markers showed that miR-199a-3p inhibited stemness of A549 cell. miR-199a-3p reduced proliferation of A549 cells, as showed with EdU staining and reduced expression of Ki67. Transfection of miR-199a-3p also promoted apoptosis, as indicated with increased apoptotic cells with flow cytometry, and increased cleaved Caspase-3/Caspase3 and Bcl-2/Bax. Apoptosis was further validated to be induced with mitochondria dysfunction, which indicated with JC-1 labeled loss of mitochondrial membrane potential, reduced activity of SOD, and increased MDA and LDH. All these effects were inverted with overexpression of ZEB1.

Conclusion

Altogether, the findings suggested that the up-regulation of miR-199a-3p significantly inhibited NSCLC growth in vivo, and reduced A549 cell proliferation and promoted mitochondrial-mediated apoptosis, through down-regulation of ZEB1. The findings supported ZEB1 down-expression with miR-199a-3p as a novel therapeutic target for NSCLC treatment.

Omega-3 Polyunsaturated Fatty Acids and Lung Cancer: nutrition or Pharmacology?

Omega-3 polyunsaturated fatty acid (ω-3 PUFA) supplements for chemoprevention of different types of cancer including lung cancer has been investigated in recent years. ω-3 PUFAs are considered immunonutrients, commonly used in the nutritional therapy of cancer patients. ω-3 PUFAs play essential roles in cell signaling and in cell structure and fluidity of membranes. They participate in the resolution of inflammation and have anti-inflammatory effects. Lung cancer patients suffer complications, such as anorexia-cachexia syndrome, pain and depression. The European Society for Clinical Nutrition and Metabolism (ESPEN) 2017 guidelines for cancer patients only discuss the use of ω-3 PUFAs for cancer-cachexia treatment, leaving aside other cancer-related complications that could potentially be managed by ω-3 PUFAs. This review aims to elucidate whether the effects of ω-3 PUFAs in lung cancer is supplementary, pharmacological or both. In addition, clinical studies, evidence in cell lines and animal models suggest how ω-3 PUFAs induce anticancer effects. ω-3 PUFAs and their metabolites are suggested to modulate pivotal pathways underlying the progression or complications of lung cancer, indicating that this is a promising field to be explored. Further investigation is still required to analyze the benefits of ω-3 PUFAs as supplementation or pharmacological treatment in lung cancer.

Context specificity of the EMT transcriptional response

Epithelial–mesenchymal plasticity contributes to many biological processes, including tumor progression. Various epithelial–mesenchymal transition (EMT) responses have been reported and no common, EMT-defining gene expression program has been identified. Here, we have performed a comparative analysis of the EMT response, leveraging highly multiplexed single-cell RNA sequencing (scRNA-seq) to measure expression profiles of 103,999 cells from 960 samples, comprising 12 EMT time course experiments and independent kinase inhibitor screens for each. We demonstrate that the EMT is vastly context specific, with an average of only 22% of response genes being shared between any two conditions, and over half of all response genes were restricted to 1–2 time course experiments. Further, kinase inhibitor screens revealed signaling dependencies and modularity of these responses. These findings suggest that the EMT is not simply a single, linear process, but is highly variable and modular, warranting quantitative frameworks for understanding nuances of the transition.

It is unclear if a common EMT expression program exists. Here, the authors perform multiplexed single-cell RNA sequencing across 12 EMT time courses and 16 kinase inhibitor screens, and find that EMT transcriptional responses are context specific and EMT is not a single, linear transition.

CDP-diacylglycerol, a critical intermediate in lipid metabolism

The roles of lipids expand beyond the basic building blocks of biological membranes. In addition to forming complex and dynamic barriers, the thousands of different lipid species in the cell contribute to essentially all the processes of life. Specific lipids are increasingly identified in cellular processes, including signal transduction, membrane trafficking, metabolic control and protein regulation. Tight control of their synthesis and degradation is essential for homeostasis. Most of the lipid molecules in the cell originate from a small number of critical intermediates. Thus, regulating the synthesis of intermediates is essential for lipid homeostasis and optimal biological functions. Cytidine diphosphate diacylglycerol (CDP-DAG) is an intermediate which occupies a branch point in lipid metabolism. CDP-DAG is incorporated into different synthetic pathways to form distinct phospholipid end-products depending on its location of synthesis. Identification and characterization of CDP-DAG synthases which catalyze the synthesis of CDP-DAG has been hampered by difficulties extracting these membrane-bound enzymes for purification. Recent developments have clarified the cellular localization of the CDP-DAG synthases and identified a new unrelated CDP-DAG synthase enzyme. These findings have contributed to a deeper understanding of the extensive synthetic and signaling networks stemming from this key lipid intermediate.

CDP-Diacylglycerol Synthases (CDS): Gateway to Phosphatidylinositol and Cardiolipin Synthesis

Cytidine diphosphate diacylglycerol (CDP-DAG) is a key intermediate in the synthesis of phosphatidylinositol (PI) and cardiolipin (CL). Both PI and CL have highly specialized roles in cells. PI can be phosphorylated and these phosphorylated derivatives play major roles in signal transduction, membrane traffic, and maintenance of the actin cytoskeletal network. CL is the signature lipid of mitochondria and has a plethora of functions including maintenance of cristae morphology, mitochondrial fission, and fusion and for electron transport chain super complex formation. Both lipids are synthesized in different organelles although they share the common intermediate, CDP-DAG. CDP-DAG is synthesized from phosphatidic acid (PA) and CTP by enzymes that display CDP-DAG synthase activities. Two families of enzymes, CDS and TAMM41, which bear no sequence or structural relationship, have now been identified. TAMM41 is a peripheral membrane protein localized in the inner mitochondrial membrane required for CL synthesis. CDS enzymes are ancient integral membrane proteins found in all three domains of life. In mammals, they provide CDP-DAG for PI synthesis and for phosphatidylglycerol (PG) and CL synthesis in prokaryotes. CDS enzymes are critical for maintaining phosphoinositide levels during phospholipase C (PLC) signaling. Hydrolysis of PI (4,5) bisphosphate by PLC requires the resynthesis of PI and CDS enzymes catalyze the rate-limiting step in the process. In mammals, the protein products of two CDS genes (CDS1 and CDS2) localize to the ER and it is suggested that CDS2 is the major CDS for this process. Expression of CDS enzymes are regulated by transcription factors and CDS enzymes may also contribute to CL synthesis in mitochondria. Studies of CDS enzymes in protozoa reveal spatial segregation of CDS enzymes from the rest of the machinery required for both PI and CL synthesis identifying a key gap in our understanding of how CDP-DAG can cross the different membrane compartments in protozoa and in mammals.

Thyroid hormone induces progression and invasiveness of squamous cell carcinomas by promoting a ZEB-1/E-cadherin switch

Epithelial tumor progression often involves epithelial-mesenchymal transition (EMT). We report that increased intracellular levels of thyroid hormone (TH) promote the EMT and malignant evolution of squamous cell carcinoma (SCC) cells. TH induces the EMT by transcriptionally up-regulating ZEB-1, mesenchymal genes and metalloproteases and suppresses E-cadherin expression. Accordingly, in human SCC, elevated D2 (the T3-producing enzyme) correlates with tumor grade and is associated with an increased risk of postsurgical relapse and shorter disease-free survival. These data provide the first in vivo demonstration that TH and its activating enzyme, D2, play an effective role not only in the EMT but also in the entire neoplastic cascade starting from tumor formation up to metastatic transformation, and supports the concept that TH is an EMT promoter. Our studies indicate that tumor progression relies on precise T3 availability, suggesting that pharmacological inactivation of D2 and TH signaling may suppress the metastatic proclivity of SCC.

Sustained phospholipase C stimulation of H9c2 cardiomyoblasts by vasopressin induces an increase in CDP-diacylglycerol synthase 1 (CDS1) through protein kinase C and cFos

Chronic stimulation (24 h) with vasopressin leads to hypertrophy in H9c2 cardiomyoblasts and this is accompanied by continuous activation of phospholipase C. Consequently, vasopressin stimulation leads to a depletion of phosphatidylinositol levels. The substrate for phospholipase C is phosphatidylinositol (4, 5) bisphosphate (PIP2) and resynthesis of phosphatidylinositol and its subsequent phosphorylation maintains the supply of PIP2. The resynthesis of PI requires the conversion of phosphatidic acid to CDP-diacylglycerol catalysed by CDP-diacylglycerol synthase (CDS) enzymes. To examine whether the resynthesis of PI is regulated by vasopressin stimulation, we focussed on the CDS enzymes. Three CDS enzymes are present in mammalian cells: CDS1 and CDS2 are integral membrane proteins localised at the endoplasmic reticulum and TAMM41 is a peripheral protein localised in the mitochondria. Vasopressin selectively stimulates an increase CDS1 mRNA that is dependent on protein kinase C, and can be inhibited by the AP-1 inhibitor, T-5224. Vasopressin also stimulates an increase in cFos protein which is inhibited by a protein kinase C inhibitor. We conclude that vasopressin stimulates CDS1 mRNA through phospholipase C, protein kinase C and cFos and provides a potential mechanism for maintenance of phosphatidylinositol levels during long-term phospholipase C signalling.

Phosphatidylinositol synthesis at the endoplasmic reticulum

Phosphatidylinositol (PI) is a minor phospholipid with a characteristic fatty acid profile; it is highly enriched in stearic acid at the sn-1 position and arachidonic acid at the sn-2 position. PI is phosphorylated into seven specific derivatives, and individual species are involved in a vast array of cellular functions including signalling, membrane traffic, ion channel regulation and actin dynamics. De novo PI synthesis takes place at the endoplasmic reticulum where phosphatidic acid (PA) is converted to PI in two enzymatic steps. PA is also produced at the plasma membrane during phospholipase C signalling, where hydrolysis of phosphatidylinositol (4,5) bisphosphate (PI(4,5)P₂) leads to the production of diacylglycerol which is rapidly phosphorylated to PA. This PA is transferred to the ER to be also recycled back to PI. For the synthesis of PI, CDP-diacylglycerol synthase (CDS) converts PA to the intermediate, CDP-DG, which is then used by PI synthase to make PI. The de novo synthesised PI undergoes remodelling to acquire its characteristic fatty acid profile, which is altered in p53-mutated cancer cells. In mammals, there are two CDS enzymes at the ER, CDS1 and CDS2. In this review, we summarise the de novo synthesis of PI at the ER and the enzymes involved in its subsequent remodelling to acquire its characteristic acyl chains. We discuss how CDS, the rate limiting enzymes in PI synthesis are regulated by different mechanisms. During phospholipase C signalling, the CDS1 enzyme is specifically upregulated by cFos via protein kinase C.

Cause-and-Effect relationship between FGFR1 expression and epithelial-mesenchymal transition in EGFR-mutated non-small cell lung cancer cells

OBJECTIVES

Increased FGFR1 expression is associated with resistance to tyrosine kinase inhibitors (TKIs) in EGFR-mutated NSCLC cells and often concomitant with epithelial to mesenchymal transition (EMT). However, the cause-and-effect relationship between increased FGFR1 expression and EMT in the genetic background of EGFR-mutated non-small cell lung cancer (NSCLC) cells is not clear. Previous studies have specifically addressed the relationship between EMT and increased FGFR1 expression in the context of simultaneous TKI-mediated blocking of EGFR-signaling. Here, in the context of EGFR-mutated NSCLC cells with active EGFR-signaling, we have examined whether increased FGFR1 expression drives EMT or is an EMT passenger event.

MATERIALS AND METHODS

For cause-and-effect analyses between EMT and FGFR1 expression, including expression of alternative spliced FGFR1 isoforms, we used CRISPR-dCAS9-SAM-mediated induction of the endogenous FGFR1 and ZEB1 genes, as well as biochemical EMT-induction, in PC9 and HCC827 NSCLC cell lines harboring activating EGFR-mutations.

RESULTS

We find that FGFR1 expression correlates with a ZEB1-associated EMT gene expression profile in NSCLC cells. In experiments using NSCLC cell lines harboring activating EGFR-mutations we show that CRISPR-dCAS9-SAM-mediated induction of FGFR1 expression is neither driving an increase in ZEB1 expression nor EMT characteristics. However, CRISPR-dCAS9-SAM-mediated induction of ZEB1 expression drives EMT characteristics and an increase in FGFR1 expression. Biochemical induction of EMT also drives an increase in FGFR1 expression.

CONCLUSION

From our findings concerning the cause-and-effect relationship in the genetic background of EGFR-mutated NSCLC cells, we conclude that an increase in ZEB1 expression is a driver of EMT resulting in concomitant increased FGFR1 expression, whereas an increase in FGFR1 expression is insufficient to drive concomitant EMT.

Extracellular Acidosis Modulates the Expression of Epithelial-Mesenchymal Transition (EMT) Markers and Adhesion of Epithelial and Tumor Cells

Epithelial-to-mesenchymal transition (EMT) is an important process of tumor progression associated with increased metastatic potential. EMT can be activated by external triggers such as cytokines or metabolic parameters (e.g. hypoxia). Since extracellular acidosis is a common finding in tumors, the aim of the study is to analyze its impact on the expression of EMT markers in vitro and in vivo as well as the functional impact on cell adhesion. Therefore, three tumor and two normal epithelial cell lines were incubated for 24 h at pH 6.6 and the expression of EMT markers was studied. In addition, mRNA expression of transcription and metabolic factors related to EMT was measured as well as the functional impact on cell adhesion, either during acidic incubation or after priming cells in an acidic milieu. E-cadherin and N-cadherin were down-regulated in all tumor and normal cell lines studied, whereas vimentin expression increased in only two tumor and one normal cell line. Down-regulation of the cadherins was seen in total protein and to a lesser extent in surface protein. In vivo an increase in N-cadherin and vimentin expression was found. Acidosis up-regulated Twist1 and Acsl1 but down-regulated fumarate hydratase (Fh). Cell adhesion during acidic incubation decreased in AT1 prostate carcinoma cells whereas preceding acidic priming increased their subsequent adhesion. Low tumor pH is able to modulate the expression EMT-related proteins and by this may affect the stability of the tissue structure.

EMT is associated with an epigenetic signature of ECM remodeling genes

Type III epithelial–mesenchymal transition (EMT) has been previously associated with increased cell migration, invasion, metastasis, and therefore cancer aggressiveness. This reversible process is associated with an important gene expression reprogramming mainly due to epigenetic plasticity. Nevertheless, most of the studies describing the central role of epigenetic modifications during EMT were performed in a single-cell model and using only one mode of EMT induction. In our study, we studied the overall modulations of gene expression and epigenetic modifications in four different EMT-induced cell models issued from different tissues and using different inducers of EMT. Pangenomic analysis (transcriptome and ChIP–sequencing) validated our hypothesis that gene expression reprogramming during EMT is largely regulated by epigenetic modifications of a wide range of genes. Indeed, our results confirmed that each EMT model is unique and can be associated with a specific transcriptome profile and epigenetic program. However, we could select some genes or pathways that are similarly regulated in the different models and that could therefore be used as a common signature of all EMT models and become new biomarkers of the EMT phenotype. As an example, we can cite the regulation of gene-coding proteins involved in the degradation of the extracellular matrix (ECM), which are highly induced in all EMT models. Based on our investigations and results, we identified ADAM19 as a new biomarker of in vitro and in vivo EMT and we validated this biological new marker in a cohort of non-small lung carcinomas.

Withaferin A inhibits Epithelial to Mesenchymal Transition in Non-Small Cell Lung Cancer Cells

Lung cancer is the leading cause of cancer-related deaths worldwide and in the United States. Despite recent advancements in treatment approaches, metastasis remains a major therapeutic challenge in lung cancer and explains the extremely poor prognosis. Epithelial to mesenchymal transition (EMT), a complex process of cellular reprogramming has become an attractive drug target because it plays a crucial role in the metastasis of non-small cell lung cancer (NSCLC). In the present study, we examined the effects of withaferin A (WFA), a plant-derived steroidal lactone on EMT in human NSCLC cell lines. First, we demonstrated that WFA displayed time- and concentration-dependent cytotoxicity on A549 and H1299 NSCLC cells. Then, cells were exposed to ≤ 0.5 µM WFA for ≤ 4 h to minimize cytotoxicity and determined its effects on EMT, cell adhesion, motility, migration, and invasion. EMT induction was performed by culturing cells in serum-free media containing TGFβ1 (5 ng/mL) and TNFα (25 ng/mL) for 48 h. We observed that pretreatment of cells with WFA inhibited cell adhesion, migration, and invasion of A549 and H1299 cells. Using western blot, immunofluorescence, and qRT-PCR analysis, we demonstrated that WFA suppressed TGFβ1 and TNFα-induced EMT in both cell lines. Mechanistically, WFA suppressed the phosphorylation and nuclear translocation of Smad2/3 and NF-κB in A549 and H1299 cells. Together, our study provides additional evidence demonstrating the inhibitory effects of WFA on EMT induction in NSCLC cells and further demonstrates the therapeutic potential of WFA against the metastasis in NSCLC.

Interconnected feedback loops among ESRP1, HAS2, and CD44 regulate epithelial-mesenchymal plasticity in cancer

Aberrant activation of epithelial-mesenchymal transition (EMT) in carcinoma cells contributes to increased migration and invasion, metastasis, drug resistance, and tumor-initiating capacity. EMT is not always a binary process; rather, cells may exhibit a hybrid epithelial/mesenchymal (E/M) phenotype. ZEB1-a key transcription factor driving EMT-can both induce and maintain a mesenchymal phenotype. Recent studies have identified two novel autocrine feedback loops utilizing epithelial splicing regulatory protein 1 (ESRP1), hyaluronic acid synthase 2 (HAS2), and CD44 which maintain high levels of ZEB1. However, how the crosstalk between these feedback loops alters the dynamics of epithelial-hybrid-mesenchymal transition remains elusive. Here, using an integrated theoretical-experimental framework, we identify that these feedback loops can enable cells to stably maintain a hybrid E/M phenotype. Moreover, computational analysis identifies the regulation of ESRP1 as a crucial node, a prediction that is validated by experiments showing that knockdown of ESRP1 in stable hybrid E/M H1975 cells drives EMT. Finally, in multiple breast cancer datasets, high levels of ESRP1, ESRP1/HAS2, and ESRP1/ZEB1 correlate with poor prognosis, supporting the relevance of ZEB1/ESRP1 and ZEB1/HAS2 axes in tumor progression. Together, our results unravel how these interconnected feedback loops act in concert to regulate ZEB1 levels and to drive the dynamics of epithelial-hybrid-mesenchymal transition.

Bulk tumour cell migration in lung carcinomas might be more common than epithelial-mesenchymal transition and be differently regulated

Background

Epithelial-to-mesenchymal transition (EMT) is one mechanism of carcinoma migration, while complex tumour migration or bulk migration is another - best demontrated by tumour cells invading blood vessels.

Methods

Thirty cases of non-small cell lung carcinomas were used for identifying genes responsible for bulk cell migration, 232 squamous cell and adenocarcinomas to identify bulk migration rates. Genes expressed differently in the primary tumour and in the invasion front were regarded as relevant in migration and further validated in 528 NSCLC cases represented on tissue microarrays (TMAs) and metastasis TMAs.

Results

Markers relevant for bulk cancer cell migration were regulated differently when compared with EMT: Twist expressed in primary tumour, invasion front, and metastasis was not associated with TGFβ1 and canonical Wnt, as Slug, Snail, and Smads were negative and β-Catenin expressed membraneously. In the majority of tumours, E-Cadherin was downregulated at the invasive front, but not absent, but, coexpressed with N-Cadherin. Vimentin was coexpressed with cytokeratins at the invasion site in few cases, whereas fascin expression was seen in a majority. Expression of ERK1/2 was downregulated, PLCγ was only expressed at the invasive front and in metastasis. Brk and Mad, genes identified in Drosophila border cell migration, might be important for bulk migration and metastasis, together with invadipodia proteins Tks5 and Rab40B, which were only upregulated at the invasive front and in metastasis. CXCR1 was expressed equally in all carcinomas, as opposed to CXCR2 and 4, which were only expressed in few tumours.

Conclusion

Bulk cancer cell migration seems predominant in AC and SCC. Twist, vimentin, fascin, Mad, Brk, Tsk5, Rab40B, ERK1/2 and PLCγ are associated with bulk cancer cell migration. This type of migration requires an orchestrated activation of proteins to keep the cells bound to each other and to coordinate movement. This hypothesis needs to be proven experimentally.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-4640-y) contains supplementary material, which is available to authorized users.

Overexpression of MCPH1 inhibits the migration and invasion of lung cancer cells

Background

The role of dysfunction of MCPH1, a recently identified tumor suppressor gene, has not yet been established in lung cancer. In our previous study, it was reported that MCPH1 expression is downregulated in lung cancer tissues and that MCPH1 overexpression inhibits the proliferation of non-small-cell lung cancer cells. The results can be found in the APJC and Oncology Letters journals.

Methods

Kaplan-Meier survival analysis was conducted to explore the prognostic significance of MCPH1. Cell experiments were performed to investigate the effects of MCPH1 on the biologic behaviors of lung cancer cells.

Results

In the current study, microarray analysis of MCPH1 revealed that lung cancer patients with high MCPH1 expression had longer relapse-free survival. Overexpression of MCPH1 in A549 lung carcinoma cells successfully inhibited cell migration and invasion. Moreover, overexpression of MCPH1 inhibited migration and invasion by regulating the activities of several proteins that control the epithelial–mesenchymal transition, such as Slug, Snail, E-cadherin, Mdm2, and p53.

Conclusion

Our results indicate that downregulation of MCPH1 correlates with tumor progression in lung cancer, and hence MCPH1 may be an important tumor suppressor gene and a novel candidate therapeutic target in lung cancer.

SPOP, ZEB-1 and E-cadherin expression in clear cell renal cell carcinoma (cc-RCC): Clinicopathological and prognostic significance

BACKGROUND

Clear cell renal cell carcinoma (cc-RCC), is a serious cancer regarding; its fatality, liability for metastases and chemoresistance, so identification of recent therapeutic targets to improve the patients prognosis is needed. SPOP is a BTB/POZ domain containing speckle-type POZ protein, has been identified as an E3 ubiquitin ligase component. ZEB1 is an essential epithelial mesenchymal transition (EMT) activator; E-cadherin is a cell adhesion protein that had been detected in normal epithelial cells membrane.

AIM

Was to assess the tissue protein markers SPOP, ZEB1 & E-cadherin expressions in benign areas of neoplastic kidney specimens and in cc-RCC patients, then correlating their expression levels with patients clinicopathological and prognostic data.

METHODS

We evaluated SPOP, ZEB-1 & E-cadherin expression using immunohistochemistry in samples from 50 cc-RCC and 20 benign areas of neoplastic kidney specimens, then we followed our patients for 5 years and finally we have analyzed correlations between the levels of markers expressions with patients clinicopathological and prognostic criteria in cc-RCC.

RESULTS

Positive expression of SPOP & ZEB1 in addition to negative E- cadherin expression was detected in cc-RCC more than benign areas of neoplastic kidney specimens (p = 0.004 and p < 0.001 respectively). In cc-RCC Positive expression of SPOP, ZEB1 and negative E- cadherin expression was associated with higher grade (p = 0.006, 0.007 & <0.001 respectively), advanced AJCC stage (p = 0.013, 0.023 & <0.001 respectively), presence of L.N metastases (p = 0.002 = 0.010 and <0.001 respectively), distant metastases (p = 0.001, 0.003 & 0.035 respectively), poor PFS and OS rates (p < 0.001 and p = 0.013 respectively).

CONCLUSION

Positive expression of SPOP& ZEB1 in addition to negative E- cadherin are associated with poor prognosis in cc-RCC patients.

Nfe2l1-silenced insulinoma cells acquire aggressiveness and chemoresistance

The transcription factor nuclear factor erythroid 2-like 1 (NFE2L1 or NRF1) is involved in various critical cell processes such as maintenance of ubiquitin-proteasome system and regulation of the cellular antioxidant response. We previously determined that pancreatic β-cell-specific Nfe2l1-knockout mice had hyperinsulinemia and that silencing of Nfe2l1 in mouse islets or MIN6 insulinoma β-cells induced elevated basal insulin release and altered glucose metabolism. Hypoglycemia is a major issue with aggressive insulinomas, although a role of NFE2L1 in this pathology is not defined. In the present work, we studied the tumorigenicity of Nfe2l1-deficient insulinoma MIN6 cells (Nfe2l1-KD) and sensitivity to chemotherapy. Nfe2l1-KD cells grew faster and were more aggressive than Scramble cells in vitro In a mouse allograft transplantation model, insulinomas arising from Nfe2l1-KD cells were more aggressive and chemoresistant. The conclusion was amplified using streptozotocin (STZ) administration in an allograft transplantation model in diabetic Akita background mice. Furthermore, Nfe2l1-KD cells were resistant to damage by the chemotherapeutic drugs STZ and 5-fluorouracil, which was linked to binding of hexokinase 1 with mitochondria, enhanced mitochondrial membrane potential and closed mitochondrial potential transition pore. Overall, both in vitro and in vivo data from Nfe2l1-KD insulinoma cells provided evidence of a previously un-appreciated action of NFE2L1 in suppression of tumorigenesis. Nfe2l1 silencing desensitizes insulinoma cells and derived tumors to chemotherapeutic-induced damage, likely via metabolic reprograming. These data indicate that NFE2L1 could potentially play an important role in the carcinogenic process and impact chemosensitivity, at least within a subset of pancreatic endocrine tumors.

PD-L1 expression is regulated by both DNA methylation and NF-kB during EMT signaling in non-small cell lung carcinoma

Tumor cells, which undergo Epithelial-mesenchymal transition (EMT) acquire increased capacities of proliferation, invasion and have the ability to generate metastases by escaping the immune system during their systemic migration. To escape the immune system, cancer cells may induce tolerance or resist elimination by immune effectors via multiple mechanisms and we hypothesized that EMT may control the expression of immune checkpoint inhibitors, then promoting immune evasion. PD-L1 (programmed cell death ligand 1) but not PD-L2 nor Galectin 9 or Death receptor (DR4, DR5 and Fas) and ligands (FasL and TRAIL) expression was up-regulated during cytokine-driven EMT in a reversible manner. Moreover PD-L1 is overexpressed in VIMENTIN positive NSCLC tissues. We also demonstrated that the expression of PD-L1 required both TNFα and TGFβ1. Indeed, TGFβ1 decreased DNMT1 content and that resulted in PD-L1 promoter demethylation whereas TNFα induced the NF-κB pathway that promoted expression of demethylated PD-L1 promoter.

Epithelial-to-Mesenchymal Transition Antagonizes Response to Targeted Therapies in Lung Cancer by Suppressing BIM

Purpose: Epithelial-to-mesenchymal transition (EMT) confers resistance to a number of targeted therapies and chemotherapies. However, it has been unclear why EMT promotes resistance, thereby impairing progress to overcome it.Experimental Design: We have developed several models of EMT-mediated resistance to EGFR inhibitors (EGFRi) in EGFR-mutant lung cancers to evaluate a novel mechanism of EMT-mediated resistance.Results: We observed that mesenchymal EGFR-mutant lung cancers are resistant to EGFRi-induced apoptosis via insufficient expression of BIM, preventing cell death despite potent suppression of oncogenic signaling following EGFRi treatment. Mechanistically, we observed that the EMT transcription factor ZEB1 inhibits BIM expression by binding directly to the BIM promoter and repressing transcription. Derepression of BIM expression by depletion of ZEB1 or treatment with the BH3 mimetic ABT-263 to enhance "free" cellular BIM levels both led to resensitization of mesenchymal EGFR-mutant cancers to EGFRi. This relationship between EMT and loss of BIM is not restricted to EGFR-mutant lung cancers, as it was also observed in KRAS-mutant lung cancers and large datasets, including different cancer subtypes.Conclusions: Altogether, these data reveal a novel mechanistic link between EMT and resistance to lung cancer targeted therapies. Clin Cancer Res; 24(1); 197-208. ©2017 AACR.

Impact of suppression of tumorigenicity 14 (ST14)/serine protease 14 (Prss14) expression analysis on the prognosis and management of estrogen receptor negative breast cancer

To elucidate the role of a type II transmembrane serine protease, ST14/Prss14, during breast cancer progression, we utilized publically accessible databases including TCGA, GEO, NCI-60, and CCLE. Survival of breast cancer patients with high ST14/Prss14 expression is significantly poor in estrogen receptor (ER) negative populations regardless of the ratios of ST14/Prss14 to its inhibitors, SPINT1 or SPINT2. In a clustering of 1085 selected EMT signature genes, ST14/Prss14 is located in the same cluster with CDH3, and closer to post-EMT markers, CDH2, VIM, and FN1 than to the pre-EMT marker, CDH1. Coexpression analyses of known ST14/Prss14 substrates and transcription factors revealed context dependent action. In cell lines, paradoxically, ST14/Prss14 expression is higher in the ER positive group and located closer to CDH1 in clustering. This apparent contradiction is not likely due to ST14/Prss14 expression in a cancer microenvironment, nor due to negative regulation by ER. Genes consistently coexpressed with ST14/Prss14 include transcription factors, ELF5, GRHL1, VGLL1, suggesting currently unknown mechanisms for regulation. Here, we report that ST14/Prss14 is an emerging therapeutic target for breast cancer where HER2 is not applicable. In addition we suggest that careful conclusions should be drawn not exclusively from the cell line studies for target development.

Mitochondrial CDP-diacylglycerol synthase activity is due to the peripheral protein, TAMM41 and not due to the integral membrane protein, CDP-diacylglycerol synthase 1

CDP diacylglycerol synthase (CDS) catalyses the conversion of phosphatidic acid (PA) to CDP-diacylglycerol, an essential intermediate in the synthesis of phosphatidylglycerol, cardiolipin and phosphatidylinositol (PI). CDS activity has been identified in mitochondria and endoplasmic reticulum of mammalian cells apparently encoded by two highly-related genes, CDS1 and CDS2. Cardiolipin is exclusively synthesised in mitochondria and recent studies in cardiomyocytes suggest that the peroxisome proliferator-activated receptor γ coactivator 1 (PGC-1α and β) serve as transcriptional regulators of mitochondrial biogenesis and up-regulate the transcription of the CDS1 gene. Here we have examined whether CDS1 is responsible for the mitochondrial CDS activity. We report that differentiation of H9c2 cells with retinoic acid towards cardiomyocytes is accompanied by increased expression of mitochondrial proteins, oxygen consumption, and expression of the PA/PI binding protein, PITPNC1, and CDS1 immunoreactivity. Both CDS1 immunoreactivity and CDS activity were found in mitochondria of H9c2 cells as well as in rat heart, liver and brain mitochondria. However, the CDS1 immunoreactivity was traced to a peripheral p55 cross-reactive mitochondrial protein and the mitochondrial CDS activity was due to a peripheral mitochondrial protein, TAMM41, not an integral membrane protein as expected for CDS1. TAMM41 is the mammalian equivalent of the recently identified yeast protein, Tam41. Knockdown of TAMM41 resulted in decreased mitochondrial CDS activity, decreased cardiolipin levels and a decrease in oxygen consumption. We conclude that the CDS activity present in mitochondria is mainly due to TAMM41, which is required for normal mitochondrial function.