The epithelial-mesenchymal transition (EMT), one of the main mechanisms underlying development of cancer metastasis, induces stem-like properties in epithelial cells. Bmi1 is a polycomb-group protein that maintains self-renewal, and is frequently overexpressed in human cancers. Here, we show the direct regulation of BMI1 by the EMT regulator, Twist1. Furthermore, Twist1 and Bmi1 were mutually essential to promote EMT and tumour-initiating capability. Twist1 and Bmi1 act cooperatively to repress expression of both E-cadherin and p16INK4a. In patients with head and neck cancers, increased levels of both Twist1 and Bmi1 correlated with downregulation of E-cadherin and p16INK4a, and was associated with the worst prognosis. These results suggest that Twist1-induced EMT and tumour-initiating capability in cancer cells occurs through chromatin remodelling, which leads to unfavourable clinical outcomes.

Asymmetrical cell division (ACD) maintains the proper number of stem cells to ensure self-renewal. In cancer cells, the deregulation of ACD disrupts the homeostasis of the stem cell pool and promotes tumour growth. However, this mechanism is unclear. Here, we show a reduction of ACD in spheroid-derived colorectal cancer stem cells (CRCSCs) compared with differentiated cancer cells. The epithelial-mesenchymal transition (EMT) inducer Snail is responsible for the ACD-to-symmetrical cell division (SCD) switch in CRCSCs. Mechanistically, Snail induces the expression of microRNA-146a (miR-146a) through the β-catenin-TCF4 complex. miR-146a targets Numb to stabilize β-catenin, which forms a feedback circuit to maintain Wnt activity and directs SCD. Interference with the Snail-miR-146a–β-catenin loop by inhibiting the MEK or Wnt activity reduces the symmetrical division of CRCSCs and attenuates tumorigenicity. In colorectal cancer patients, the Snail(High)Numb(Low) profile is correlated with cetuximab resistance and a poorer prognosis. This study elucidates a unique mechanism of EMT-induced CRCSC expansion.

Epithelial-mesenchymal transition (EMT), which is characterized by the suppression of the adhesion protein E-cadherin, is a crucial process that promotes metastasis and stem-like properties of cancer cells. However, the dissociation of cellular aggregates is not sufficient to explain why cancer cells move, and the motile nature of cancer cells undergoing EMT remains elusive. Here, we identify a mechanism in which the EMT inducer Twist1 elicits cancer cell movement through activation of RAC1. Twist1 cooperates with BMI1 to suppress let-7i expression, which results in upregulation of NEDD9 and DOCK3, leading to RAC1 activation and enabling mesenchymal-mode movement in three-dimensional environments. Moreover, the suppression of let-7i contributes to Twist1-induced stem-like properties. Clinically, activation of the Twist1-let-7i-NEDD9 axis in head and neck cancer patients correlates with tumour invasiveness and worse outcome. Our results uncover an essential mechanism to explain how Twist1 induces the motile stem-like cancer cell phenotype beyond simply suppressing E-cadherin.

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Purpose: We investigated the mechanism and clinical significance of the epithelial-mesenchymal transition (EMT)-induced chemoresistance in head and neck squamous cell carcinoma (HNSCC).Experimental Design: The correlation between the expression of different EMT regulators and chemoresistance genes, such as excision repair cross complementation group 1 (ERCC1), was evaluated in cancer cell lines from the NCI-60 database and four human HNSCC cell lines. Ectopic expression of Snail or short-interference RNA-mediated repression of Snail or ERCC1 was done in HNSCC cell lines. Cell viability was examined for cells after cisplatin treatment. A luciferase reporter assay and chromatin immunoprecipitation were used to identify the transcriptional regulation of ERCC1 by Snail. Immunohistochemical analysis of Snail, Twist1, ERCC1, hypoxia inducible factor-1 α (HIF-1α), and NBS1 were done in samples from 72 HNSCC patients receiving cisplatin-based chemotherapy.Results: The correlation between the expression of Snail and ERCC1 was confirmed in different cell lines, including HNSCC cells. In HNSCC cell lines, overexpression of Snail in the low endogenous Snail/ ERCC1 cell lines FaDu or CAL-27 increased ERCC1 expression, and hypoxia or overexpression of NBS1 also upregulated ERCC1. Knockdown of Snail in the high endogenous Snail/ERCC1 cell line OECM-1 downregulated ERCC1 expression and attenuated cisplatin resistance. Furthermore, suppression of ERCC1 in Snail-or NBS1-overexpressing HNSCC cells enhanced sensitivity to cisplatin. Snail directly regulated ERCC1 transcription. In patients with HNSCC, coexpression of Snail and ERCC1 correlated with cisplatin resistance and a poor prognosis.Conclusions: Activation of ERCC1 by Snail is critical in the generation of cisplatin resistance of HNSCC cells. Clin Cancer Res; 16(18); 4561-71. ©2010 AACR.The epithelial-mesenchymal transition (EMT), a major mechanism of cancer metastasis, is initiated by repression of the epithelial adhesion molecule E-cadherin by several transcription factors, including Snail (also known as Snail1), Slug (also known as Snail2), Twist1, Zeb1, SIP1, and E47 (1). In most human cancers, metastatic tumors are resistant to chemotherapy; therefore, patients with such tumors typically have poor outcomes. Emerging evidence suggests a correlation between EMT and the resistance to chemotherapy of cancer cells. For example, colorectal cancer cells that are resistant to oxaliplatin undergo phenotypic changes indicative of an EMT (2). Direct regulation of Akt2 by Twist contributes to paclitaxel resistance in breast cancer cells (3). Induction of EMT in breast cancer cells leads to an enrichment of cells with stem-like properties and chemoresistance (4). A recent report found that Zeb1 and other EMT regulators allow pancreatic cancer cells to maintain drug resistance (5). Taken together, these studies suggest that diverse types of cancer cells acquire drug-resistant phenotypes during EMT. Although there is an evident association among EMT, metastasis, and chemoresis...

BackgroundCell-cell interactions maintain tissue homeostasis and contribute to dynamic alteration of the tumor microenvironment (TME). Communication between cancer and host cells not only promotes advanced disease aggression but also determines therapeutic response in cancer patients. Despite accumulating evidence supporting the role of tumor-infiltrating immunocytes in modulating tumor immunity, the interplay between heterogeneous tumor subpopulations and immunocytes is elusive.MethodsWe expanded colorectal cancer stem cells (CRCSCs) as cancer spheroids from the murine colorectal cancer (CRC) cell line CT26 to interrogate tumor-host interactions using a syngeneic tumor model. RNA-sequencing analysis of host cells and tumor exosomes was performed to identify molecular determinants that mediate the crosstalk between CRCSCs and immunocytes. The Cancer Genome Atlas (TCGA) database was used to validate the clinical significance in CRC patients.ResultsThe expanded CT26 cancer spheroids showed increased stemness gene expression, enhanced spheroid and clonogenicity potential, and an elevated tumor-initiating ability, characteristic of CRCSCs. By examining immune cell composition in syngeneic tumor-bearing mice, a systemic increase in CD11b+/Ly6GHigh/Ly6CLow neutrophils was observed in mice bearing CRCSC-derived tumors. An increased secretion of CRCSC exosomes was observed in vitro, and through in vivo tracking, CRCSC exosomes were found to be transported to the bone marrow. Moreover, CRCSC exosomes prolonged the survival of bone marrow-derived neutrophils and engendered a protumoral phenotype in neutrophils. Mechanistically, tumor exosomal tri-phosphate RNAs induced the expression of interleukin-1β (IL-1β) through a pattern recognition-NF-κB signaling axis to sustain neutrophil survival. CRCSC-secreted CXCL1 and CXCL2 then attracted CRCSC-primed neutrophils to promote tumorigenesis of CRC cells via IL-1β. Moreover, neutrophil depletion using a Ly6G-specific antibody (clone 1A8) attenuated the tumorigenicity of CRCSCs. In human specimens, CRC patients exhibiting an active CRCSC signal (Snail+IL8+) showed elevated tumor infiltration of MPO+ neutrophils, and high (in the top 10%) MPO expression predicted poor survival of CRC patients.ConclusionsThis study elucidates a multistep CRCSC-neutrophil interaction during advanced cancer progression. Strategies targeting aberrant neutrophil activation may be developed for combating CSC-related malignancy.Electronic supplementary materialThe online version of this article (10.1186/s13045-019-0699-4) contains supplementary material, which is available to authorized users.

The dynamic cell–cell communication is essential for tissue homeostasis in normal physiological circumstances and contributes to a diversified tumor microenvironment. Although exosomes are extracellular vesicles that actively participate in cell–cell interaction by shutting cellular components, impacts of tumor exosomes in the context of cancer stemness remain elusive. Here, we expand colorectal cancer stem cells (CRCSCs) as cancer spheroids and demonstrate that the β‐catenin/Tcf‐4‐activated RAB27B expression is required for the secretion of CRCSC exosomes. In an exosomal RNA sequencing analysis, a switch of exosomal RNA species from retrotransposons to microRNAs (miRNAs) is identified upon expanding CRCSCs. miRNA‐146a‐5p (miR‐146a) is the major miRNA in CRCSC exosomes and exosomal miR‐146a promotes stem‐like properties and tumorigenicity by targeting Numb in recipient CRC cells. Among 53 CRC patients, those with abundant exosomal miR‐146a expression in serum exhibits higher miR‐146aHigh/NumbLow CRCSC traits, an increased number of tumor‐filtrating CD66(+) neutrophils and a decreased number of tumor‐infiltrating CD8(+) T cells. Our study elucidates a unique mechanism of tumor exosome‐mediated stemness expansion.

Adenomyosis is an oestrogen-dependent disease characterized by the invasion of endometrial epithelial cells into the myometrium of uterus, and angiogenesis is thought to be required for the implantation of endometrial glandular tissues during the adenomyotic pathogenesis. In this study, we demonstrate that compared with eutopic endometria, adenomyotic lesions exhibited increased vascularity as detected by sonography. Microscopically, the lesions also exhibited an oestrogen-associated elevation of microvascular density and VEGF expression in endometrial epithelial cells. We previously reported that oestrogen-induced Slug expression was critical for endometrial epithelial–mesenchymal transition and development of adenomyosis. Our present studies demonstrated that estradiol (E2) elicited a Slug-VEGF axis in endometrial epithelial cells, and also induced pro-angiogenic activity in vascular endothelial cells. The antagonizing agents against E2 or VEGF suppressed endothelial cells migration and tubal formation. Animal experiments furthermore confirmed that blockage of E2 or VEGF was efficient to attenuate the implantation of adenomyotic lesions. These results highlight the importance of oestrogen-induced angiogenesis in adenomyosis development and provide a potential strategy for treating adenomyosis through intercepting the E2-Slug-VEGF pathway.