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

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

Zeb1-mediated autophagy enhances resistance of breast cancer cells to genotoxic drugs.

Autophagy is a highly conserved process of cellular self-digestion that involves the formation of autophagosomes for the delivery of intracellular components and dysfunctional organelles to lysosomes. This process is induced by different signals including starvation, mitochondrial dysfunction, and DNA damage. The molecular link between autophagy and DNA damage is not well understood yet. Importantly, tumor cells utilize the mechanism of autophagy to cope with genotoxic anti-cancer drug therapy. Another mechanism of drug resistance is provided to cancer cells via the execution of the EMT program. One of the critical transcription factors of EMT is Zeb1. Here we demonstrate that Zeb1 is involved in the regulation of autophagy in several breast cancer cell models. On the molecular level, Zeb1 likely facilitates autophagy through the regulation of autophagic genes, resulting in increased LC3-II levels, augmented staining with Lysotracker, and increased resistance to several genotoxic drugs. The attenuation of Zeb1 expression in TNBC cells led to the opposite effect. Consequently, we propose that Zeb1 augments the resistance of breast cancer cells to genotoxic drugs, at least partially, via autophagy. Collectively, we have uncovered a novel function of Zeb1 in the regulation of autophagy in breast cancer cells.

ZEB1 and IL-6/11-STAT3 signalling cooperate to define invasive potential of pancreatic cancer cells via differential regulation of the expression of S100 proteins.

BACKGROUND: S100 proteins have been implicated in various aspects of cancer, including epithelial-mesenchymal transitions (EMT), invasion and metastasis, and also in inflammatory disorders. Here we examined the impact of individual members of this family on the invasion of pancreatic ductal adenocarcinoma (PDAC) cells, and their regulation by EMT and inflammation. METHODS: Invasion of PDAC cells was analysed in zebrafish embryo xenografts and in transwell invasion assays. Expression and regulation of S100 proteins was studied in vitro by immunoblotting, quantitative PCR and immunofluorescence, and in pancreatic lesions by immunohistochemistry. RESULTS: Whereas the expression of most S100 proteins is characteristic for epithelial PDAC cell lines, S100A4 and S100A6 are strongly expressed in mesenchymal cells and upregulated by ZEB1. S100A4/A6 and epithelial protein S100A14 respectively promote and represses cell invasion. IL-6/11-STAT3 pathway stimulates expression of most S100 proteins. ZEB1 synergises with IL-6/11-STAT3 to upregulate S100A4/A6, but nullifies the effect of inflammation on S100A14 expression. CONCLUSION: EMT/ZEB1 and IL-6/11-STAT3 signalling act independently and congregate to establish the expression pattern of S100 proteins, which drives invasion. Although ZEB1 regulates expression of S100 family members, these effects are masked by IL-6/11-STAT3 signalling, and S100 proteins cannot be considered as bona fide EMT markers in PDAC.

Mesenchymal-epithelial transition and AXL inhibitor TP-0903 sensitise triple-negative breast cancer cells to the antimalarial compound, artesunate.

Triple-negative breast cancer (TNBC) is a difficult-to-treat, aggressive cancer type. TNBC is often associated with the cellular program of epithelial-mesenchymal transition (EMT) that confers drug resistance and metastasis. EMT and reverse mesenchymal-epithelial transition (MET) programs are regulated by several signaling pathways which converge on a group of transcription factors, EMT- TFs. Therapy approaches could rely on the EMT reversal to sensitise mesenchymal tumours to compounds effective against epithelial cancers. Here, we show that the antimalarial ROS-generating compound artesunate (ART) exhibits higher cytotoxicity in epithelial than mesenchymal breast cancer cell lines. Ectopic expression of EMT-TF ZEB1 in epithelial or ZEB1 depletion in mesenchymal cells, respectively, reduced or increased ART-generated ROS levels, DNA damage and apoptotic cell death. In epithelial cells, ZEB1 enhanced expression of superoxide dismutase 2 (SOD2) and glutathione peroxidase 8 (GPX8) implicated in ROS scavenging. Although SOD2 or GPX8 levels were unaffected in mesenchymal cells in response to ZEB1 depletion, stable ZEB1 knockdown enhanced total ROS. Receptor tyrosine kinase AXL maintains a mesenchymal phenotype and is overexpressed in TNBC. The clinically-relevant AXL inhibitor TP-0903 induced MET and synergised with ART to generate ROS, DNA damage and apoptosis in TNBC cells. TP-0903 reduced the expression of GPX8 and SOD2. Thus, TP-0903 and ZEB1 knockdown sensitised TNBC cells to ART, likely via different pathways. Synergistic interactions between TP-0903 and ART indicate that combination approaches involving these compounds can have therapeutic prospects for TNBC treatment.

Reactive oxygen species and mitochondrial sensitivity to oxidative stress determine induction of cancer cell death by p21.

p21(Waf1/Cip1/Sdi1) is a cyclin-dependent kinase inhibitor that mediates cell cycle arrest. Prolonged p21 up-regulation induces a senescent phenotype in normal and cancer cells, accompanied by an increase in intracellular reactive oxygen species (ROS). However, it has been shown recently that p21 expression can also lead to cell death in certain models. The mechanisms involved in this process are not fully understood. Here, we describe an induction of apoptosis by p21 in sarcoma cell lines that is p53-independent and can be ameliorated with antioxidants. Similar levels of p21 and ROS caused senescence in the absence of significant death in other cancer cell lines, suggesting a cell-specific response. We also found that cells undergoing p21-dependent cell death had higher sensitivity to oxidants and a specific pattern of mitochondrial polarization changes. Consistent with this, apoptosis could be blocked with targeted expression of catalase in the mitochondria of these cells. We propose that the balance between cancer cell death and arrest after p21 up-regulation depends on the specific effects of p21-induced ROS on the mitochondria. This suggests that selective up-regulation of p21 in cancer cells could be a successful therapeutic intervention for sarcomas and tumors with lower resistance to mitochondrial oxidative damage, regardless of p53 status.

ZEB/miR-200 feedback loop: at the crossroads of signal transduction in cancer.

Embryonic differentiation programs of epithelial-mesenchymal and mesenchymal-epithelial transition (EMT and MET) represent a mechanistic basis for epithelial cell plasticity implicated in cancer. Transcription factors of the ZEB protein family (ZEB1 and ZEB2) and several microRNA species (predominantly miR-200 family members) form a double negative feedback loop, which controls EMT and MET programs in both development and tumorigenesis. In this article, we review crosstalk between the ZEB/miR-200 axis and several signal transduction pathways activated at different stages of tumor development. The close association of ZEB proteins with these pathways is indirect evidence for the involvement of a ZEB/miR-200 loop in tumor initiation, progression and spread. Additionally, the configuration of signaling pathways involving ZEB/miR-200 loop suggests that ZEB1 and ZEB2 may have different, possibly even opposing, roles in some forms of human cancer.

SIP1 protein protects cells from DNA damage-induced apoptosis and has independent prognostic value in bladder cancer.

The epithelial-mesenchymal transition (EMT) contributes to cancer metastasis. Two ZEB family members, ZEB1 and ZEB2(SIP1), inhibit transcription of the E-cadherin gene and induce EMT in vitro. However, their relevance to human cancer is insufficiently studied. Here, we performed a comparative study of SIP1 and ZEB1 proteins in cancer cell lines and in one form of human malignancy, carcinoma of the bladder. Whereas ZEB1 protein was expressed in all E-cadherin-negative carcinoma cell lines, being in part responsible for the high motility of bladder cancer cells, SIP1 was hardly ever detectable in carcinoma cells in culture. However, SIP1 represented an independent factor of poor prognosis (P = 0.005) in a series of bladder cancer specimens obtained from patients treated with radiotherapy. In contrast, ZEB1 was rarely expressed in tumor tissues; and E-cadherin status did not correlate with the patients' survival. SIP1 protected cells from UV- and cisplatin-induced apoptosis in vitro but had no effect on the level of DNA damage. The anti-apoptotic effect of SIP1 was independent of either cell cycle arrest or loss of cell-cell adhesion and was associated with reduced phosphorylation of ATM/ATR targets in UV-treated cells. The prognostic value of SIP1 and its role in DNA damage response establish a link between genetic instability and metastasis and suggest a potential importance for this protein as a therapeutic target. In addition, we conclude that the nature of an EMT pathway rather than the deregulation of E-cadherin per se is critical for the progression of the disease and patients' survival.

AXL Receptor in Cancer Metastasis and Drug Resistance: When Normal Functions Go Askew.

The TAM proteins TYRO3, AXL, and MER are receptor tyrosine kinases implicated in the clearance of apoptotic debris and negative regulation of innate immune responses. AXL contributes to immunosuppression by terminating the Toll-like receptor signaling in dendritic cells, and suppressing natural killer cell activity. In recent years, AXL has been intensively studied in the context of cancer. Both molecules, the receptor, and its ligand GAS6, are commonly expressed in cancer cells, as well as stromal and infiltrating immune cells. In cancer cells, the activation of AXL signaling stimulates cell survival and increases migratory and invasive potential. In cells of the tumour microenvironment, AXL pathway potentiates immune evasion. AXL has been broadly implicated in the epithelial-mesenchymal plasticity of cancer cells, a key factor in drug resistance and metastasis. Several antibody-based and small molecule AXL inhibitors have been developed and used in preclinical studies. AXL inhibition in various mouse cancer models reduced metastatic spread and improved the survival of the animals. AXL inhibitors are currently being tested in several clinical trials as monotherapy or in combination with other drugs. Here, we give a brief overview of AXL structure and regulation and discuss the normal physiological functions of TAM receptors, focusing on AXL. We present a theory of how epithelial cancers exploit AXL signaling to resist cytotoxic insults, in order to disseminate and relapse.

The ZEB2-dependent EMT transcriptional programme drives therapy resistance by activating nucleotide excision repair genes ERCC1 and ERCC4 in colorectal cancer.

Resistance to adjuvant chemotherapy is a major clinical problem in the treatment of colorectal cancer (CRC). The aim of this study was to elucidate the role of an epithelial to mesenchymal transition (EMT)-inducing protein, ZEB2, in chemoresistance of CRC, and to uncover the underlying mechanism. We performed IHC for ZEB2 and association analyses with clinical outcomes on primary CRC and matched CRC liver metastases in compliance with observational biomarker study guidelines. ZEB2 expression in primary tumours was an independent prognostic marker of reduced overall survival and disease-free survival in patients who received adjuvant FOLFOX chemotherapy. ZEB2 expression was retained in 96% of liver metastases. The ZEB2-dependent EMT transcriptional programme activated nucleotide excision repair (NER) pathway largely via upregulation of the ERCC1 gene and other components in NER pathway, leading to enhanced viability of CRC cells upon oxaliplatin treatment. ERCC1-overexpressing CRC cells did not respond to oxaliplatin in vivo, as assessed using a murine orthotopic model in a randomised and blinded preclinical study. Our findings show that ZEB2 is a biomarker of tumour response to chemotherapy and risk of recurrence in CRC patients. We propose that the ZEB2-ERCC1 axis is a key determinant of chemoresistance in CRC.

Novel monoclonal antibodies detect Smad-interacting protein 1 (SIP1) in the cytoplasm of human cells from multiple tumor tissue arrays.

Smad-interacting protein 1 (SIP1, also known as ZEB2) represses the transcription of E-cadherin and mediates epithelial-mesenchymal transition in development and tumor metastasis. Due to the lack of human SIP1-specific antibodies, its expression in human tumor tissues has not been studied in detail by immunohistochemistry. Hence, we generated two anti-SIP1 monoclonal antibodies, clones 1C6 and 6E5, with IgG1 and IgG2a isotypes, respectively. The specificity of these antibodies was shown by Western blotting studies using siRNA mediated downregulation of SIP1 and ZEB1 in a human osteosarcoma cell line. In the same context, we also compared them with 5 commercially available SIP1 antibodies. Antibody specificity was further verified in an inducible cell line system by immunofluorescence. By using both antibodies, we evaluated the tissue expression of SIP1 in paraffin-embedded tissue microarrays consisting of 22 normal and 101 tumoral tissues of kidney, colon, stomach, lung, esophagus, uterus, rectum, breast and liver. Interestingly, SIP1 predominantly displayed a cytoplasmic expression, while the nuclear localization of SIP1 was observed in only 6 cases. Strong expression of SIP1 was found in distal tubules of kidney, glandular epithelial cells of stomach and hepatocytes, implicating a co-expression of SIP1 and E-cadherin. Squamous epithelium of the esophagus and surface epithelium of colon and rectum were stained with moderate to weak intensity. Normal uterus, breast and lung tissues remained completely negative. By comparison with their normal tissues, we observed SIP1 overexpression in cancers of the kidney, breast, lung and uterus. However, SIP1 expression was found to be downregulated in tumors from colon, rectum, esophagus, liver and stomach tissues. Finally we did nuclear/cytoplasmic fractionation in 3 carcinoma cell lines and detected SIP1 in both fractions, nucleus being the dominant one. To our best knowledge, this is the first comprehensive immunohistochemical study of the expression of SIP1 in a series of human cancers. Our finding that SIP1 is not exclusively localized to nucleus suggests that the subcellular localization of SIP1 is regulated in normal and tumor tissues. These novel monoclonal antibodies may help elucidate the role of SIP1 in tumor development.

Direct repression of cyclin D1 by SIP1 attenuates cell cycle progression in cells undergoing an epithelial mesenchymal transition.

Zinc finger transcription factors of the Snail/Slug and ZEB-1/SIP1 families control epithelial-mesenchymal transitions in development in cancer. Here, we studied SIP1-regulated mesenchymal conversion of epidermoid A431 cells. We found that concomitant with inducing invasive phenotype, SIP1 inhibited expression of cyclin D1 and induced hypophosphorylation of the Rb tumor suppressor protein. Repression of cyclin D1 was caused by direct binding of SIP1 to three sequence elements in the cyclin D1 gene promoter. By expressing exogenous cyclin D1 in A431/SIP1 cells and using RNA interference, we demonstrated that the repression of cyclin D1 gene by SIP1 was necessary and sufficient for Rb hypophosphorylation and accumulation of cells in G1 phase. A431 cells expressing SIP1 along with exogenous cyclin D1 were highly invasive, indicating that SIP1-regulated invasion is independent of attenuation of G1/S progression. However, in another epithelial-mesenchymal transition model, gradual mesenchymal conversion of A431 cells induced by a dominant negative mutant of E-cadherin produced no effect on the cell cycle. We suggest that impaired G1/S phase progression is a general feature of cells that have undergone EMT induced by transcription factors of the Snail/Slug and ZEB-1/SIP1 families.

Zeb2 drives invasive and microbiota-dependent colon carcinoma.

Colorectal cancer (CRC) is highly prevalent in Western society, and increasing evidence indicates strong contributions of environmental factors and the intestinal microbiota to CRC initiation, progression and even metastasis. We have identified a synergistic inflammatory tumor-promoting mechanism through which the resident intestinal microbiota boosts invasive CRC development in an epithelial-to-mesenchymal transition-prone tissue environment. Intestinal epithelial cell (IEC)-specific transgenic expression of the epithelial-to-mesenchymal transition regulator Zeb2 in mice (Zeb2IEC-Tg/+) leads to increased intestinal permeability, myeloid cell-driven inflammation and spontaneous invasive CRC development. Zeb2IEC-Tg/+ mice develop a dysplastic colonic epithelium, which progresses to severely inflamed neoplastic lesions while the small intestinal epithelium remains normal. Zeb2IEC-Tg/+ mice are characterized by intestinal dysbiosis, and microbiota depletion with broad-spectrum antibiotics or germ-free rederivation completely prevents cancer development. Zeb2IEC-Tg/+ mice represent the first mouse model of spontaneous microbiota-dependent invasive CRC and will help us to better understand host-microbiome interactions driving CRC development in humans.

Lapatinib, a dual inhibitor of ErbB-1/-2 receptors, enhances effects of combination chemotherapy in bladder cancer cells.

Survival rate of patients diagnosed with the invasive form of bladder cancer is low suggesting an urgent need to implement novel treatments. GTC (gemcitabine, paclitaxel and cisplatin) is a new chemotherapeutic regimen, which has shown promise in clinical trials. Given that receptor tyrosine kinases of the ErbB family are overexpressed in a high proportion of metastatic bladder tumours, approaches involving small-molecule inhibitors of ErbB receptors in combination with conventional cytostatic drugs are of potential interest. Here, we show that the dual inhibitor of ErbB receptors, lapatinib, enhances cytostatic and induces cytotoxic effects of GTC in two bladder cancer cell lines which differ with regard to expression levels of proteins taking part in the ErbB pathway. Lapatinib inhibited phosphorylation of ErbB receptors and also reduced the level of phosphorylated AKT. Flow cytometry analysis demonstrated that GTC treatment affects cell cycle distribution differently in the presence or absence of lapatinib. In RT112 cells, which express high levels of ErbB receptors and harbour wild-type p53, combined GTC/lapatinib treatment resulted in the phosphorylation of p53 at Ser46 and accumulation of sub-G1 cell populations. Our data indicate that a combinatorial approach involving GTC and lapatinib may have therapeutic potential in a subset of bladder tumours depending on the genetic context.

EMT: A mechanism for escape from EGFR-targeted therapy in lung cancer.

Epithelial mesenchymal transition (EMT) is a reversible developmental genetic programme of transdifferentiation of polarised epithelial cells to mesenchymal cells. In cancer, EMT is an important factor of tumour cell plasticity and has received increasing attention for its role in the resistance to conventional and targeted therapies. In this paper we provide an overview of EMT in human malignancies, and discuss contribution of EMT to the development of the resistance to Epidermal Growth Factor Receptor (EGFR)-targeted therapies in non-small cell lung cancer (NSCLC). Patients with the tumours bearing specific mutations in EGFR have a good clinical response to selective EGFR inhibitors, but the resistance inevitably develops. Several mechanisms responsible for the resistance include secondary mutations in the EGFR gene, genetic or non-mutational activation of alternative survival pathways, transdifferentiation of NSCLC to the small cell lung cancer histotype, or formation of resistant tumours with mesenchymal characteristics. Mechanistically, application of an EGFR inhibitor does not kill all cancer cells; some cells survive the exposure to a drug, and undergo genetic evolution towards resistance. Here, we present a theory that these quiescent or slow-proliferating drug-tolerant cell populations, or so-called "persisters", are generated via EMT pathways. We review the EMT-activated mechanisms of cell survival in NSCLC, which include activation of ABC transporters and EMT-associated receptor tyrosine kinase AXL, immune evasion, and epigenetic reprogramming. We propose that therapeutic inhibition of these pathways would eliminate pools of persister cells and prevent or delay cancer recurrence when applied in combination with the agents targeting EGFR.

An FBXW7-ZEB2 axis links EMT and tumour microenvironment to promote colorectal cancer stem cells and chemoresistance.

Colorectal cancer (CRC) patients develop recurrence after chemotherapy owing to the survival of stem cell-like cells referred to as cancer stem-like cells (CSCs). The origin of CSCs is linked to the epithelial-mesenchymal transition (EMT) process. Currently, it remains poorly understood how EMT programmes enable CSCs residing in the tumour microenvironment to escape the effects of chemotherapy. This study identifies a key molecular pathway that is responsible for the formation of drug-resistant CSC populations. Using a modified yeast-2-hybrid system and 2D gel-based proteomics methods, we show that the E3-ubiquitin ligase FBXW7 directly binds and degrades the EMT-inducing transcription factor ZEB2 in a phosphorylation-dependent manner. Loss of FBXW7 induces an EMT that can be effectively reversed by knockdown of ZEB2. The FBXW7-ZEB2 axis regulates such important cancer cell features, as stemness/dedifferentiation, chemoresistance and cell migration in vitro, ex vivo and in animal models of metastasis. High expression of ZEB2 in cancer tissues defines the reduced ZEB2 expression in the cancer-associated stroma in patients and in murine intestinal organoids, demonstrating a tumour-stromal crosstalk that modulates a niche and EMT activation. Our study thus uncovers a new molecular mechanism, by which the CRC cells display differences in resistance to chemotherapy and metastatic potential.

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 TGFß-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.

Immediate and delayed effects of E-cadherin inhibition on gene regulation and cell motility in human epidermoid carcinoma cells.

The invasion suppressor protein, E-cadherin, plays a central role in epithelial cell-cell adhesion. Loss of E-cadherin expression or function in various tumors of epithelial origin is associated with a more invasive phenotype. In this study, by expressing a dominant-negative mutant of E-cadherin (Ec1WVM) in A431 cells, we demonstrated that specific inhibition of E-cadherin-dependent cell-cell adhesion led to the genetic reprogramming of tumor cells. In particular, prolonged inhibition of cell-cell adhesion activated expression of vimentin and repressed cytokeratins, suggesting that the effects of Ec1WVM can be classified as epithelial-mesenchymal transition. Both short-term and prolonged expression of Ec1WVM resulted in morphological transformation and increased cell migration though to different extents. Short-term expression of Ec1WVM up-regulated two AP-1 family members, c-jun and fra-1, but was insufficient to induce complete mesenchymal transition. AP-1 activity induced by the short-term expression of Ec1WVM was required for transcriptional up-regulation of AP-1 family members and down-regulation of two other Ec1WVM-responsive genes, S100A4 and igfbp-3. Using a dominant-negative mutant of c-Jun (TAM67) and RNA interference-mediated silencing of c-Jun and Fra-1, we demonstrated that AP-1 was required for cell motility stimulated by the expression of Ec1WVM. In contrast, Ec1WVM-mediated changes in cell morphology were AP-1-independent. Our data suggest that mesenchymal transition induced by prolonged functional inhibition of E-cadherin is a slow and gradual process. At the initial step of this process, Ec1WVM triggers a positive autoregulatory mechanism that increases AP-1 activity. Activated AP-1 in turn contributes to Ec1WVM-mediated effects on gene expression and tumor cell motility. These data provide novel insight into the tumor suppressor function of E-cadherin.

Erratum: Actin-binding protein alpha-actinin 4 (ACTN4) is a transcriptional co-activator of RelA/p65 sub-unit of NF-kB.

[This corrects the article DOI: 10.18632/oncotarget.901.].

Assessment of Nuclear ZEB2 as a Biomarker for Colorectal Cancer Outcome and TNM Risk Stratification.

Importance: At present, patients with colorectal cancer (CRC) are risk stratified using TNM histologic features. More recently, an association between a mesenchymal phenotype and a high risk of disease recurrence and micrometastases has been recognized. Objective: To investigate the association of the epithelial to mesenchymal transition (EMT)-inducing transcription factor ZEB2 (zinc finger E box-binding homeobox 2), survival outcomes, and the efficacy of ZEB2 as a biomarker when added as refinement to TNM staging after curative intent surgery for CRC. Design, Setting, and Participants: ZEB2 expression was assessed using a previously validated scoring system as part of a prospective, observational, masked diagnostic study from January 1, 2008, to December 31, 2013. Data were prospectively collected and analyzed for association with oncologic outcomes from January 1, 2017, to December 31, 2018. An initial test cohort from an academic university medical center of 126 consecutive patients with CRC and, subsequently, an independent validation cohort of 210 patients were examined. ZEB2 positivity was scored by 2 independent, masked pathologists. External validity was tested using an open access gene expression portal. Nomograms were developed with or without ZEB2. Main Outcomes and Measures: Systemic and local recurrence of CRC. Results: The test cohort consisted of 126 consecutive patients (mean [SD] age, 72.7 [11.7] years; 61 [48.4%] male) and the validation cohort of 210 patients (mean [SD] age, 72.0 [10.6] years; 111 [52.9%] male). A total of 52 tumors (41.3%) in the test cohort and 104 (49.5%) in the validation cohort were scored nuclear ZEB2 positive. Survival analysis by the log-rank test found that ZEB2 expression was associated with a significant reduction in overall survival and disease-free survival in both cohorts. Cox proportional hazards regression analysis highlighted ZEB2 as an independent biomarker of shorter overall survival and disease-free survival. Analysis of node-negative disease (n = 222) identified ZEB2 as an independent biomarker of early recurrence and reduced survival. External validation confirmed these findings. Addition of ZEB2 expression to nomograms composed of conventional TNM risk factors improved the ability to identify patients at high risk of recurrence demonstrated by the improvement in concordance index in both test (0.73 to 0.77) and validation (0.82 to 0.87) cohorts. Conclusions and Relevance: The findings suggest that expression of ZEB2 is associated with poor oncologic outcome and distant recurrence. The study also found that the addition of ZEB2 to existing TNM classification improved the ability to stratify patients for risk of recurrence. The results of this study suggest that addition of ZEB2 expression status to the TNM staging system improves the ability to stratify patients at high risk of recurrence.