上皮间质转化与肿瘤干细胞

上皮-间质转化(EMT)是生物胚胎发育的基础过程,与肿瘤细胞的原位侵袭和远处转移也密切相关.EMT与肿瘤干细胞(CSC)关系密切.CSC有较强的自我更新和致瘤能力以及细胞分化潜能.通过对CSC标志物的鉴定,深入研究其耐药性,可为肿瘤治疗提供新径.     

上皮细胞间质转化与肿瘤干细胞

Epithelial-mesenchymal transition (EMT) not only can endow cells migration and invasion characteristics, but also can make tumor cells obtain self-renewal ability and have the characteristics of stem cells, which might result in cancer stem cell (CSC). There are the same molecular mechanism and microenvironment between EMT and CSC, which have great clinic significances for the diagnosis and treatment of the aggressive cancers. Moreover, many studies show that miR-200 could regulate EMT and CSC, participate in the tumor invasion and metastasi, and promote the research of targeted cancer therapy.     

上皮间充质转化与肿瘤干细胞的研究进展

上皮细胞间充质转化(epithelial-mesenchymal transition, EMT) 在胚胎发育和肿瘤发生中具有重要作用, EMT可使上皮性肿瘤细胞获得间充质细胞表型, 在增强肿瘤细胞的侵袭和转移能力的同时, 也使得肿瘤细胞具有自我更新能力等干细胞样特性。多种转录因子、信号转导通路、microRNAs及细胞微环境等因素共同调控此过程。EMT与肿瘤干细胞之间有密不可分的联系, EMT可以促进肿瘤细胞获得干细胞特征, 具有干细胞特征的肿瘤细胞高表达EMT标记分子, microRNA可同时调控EMT和细胞干性。阐明EMT与肿瘤干细胞的相互关系及其调控机制, 有望为肿瘤转移与复发的靶向治疗开辟新思路。      

Epithelial-mesenchymal transition and cancer stem cells: a dangerously dynamic duo in breast cancer progression

Aberrant activation of a latent embryonic program - known as the epithelial-mesenchymal transition (EMT) - can endow cancer cells with the migratory and invasive capabilities associated with metastatic competence. The induction of EMT entails the loss of epithelial characteristics and the de novo acquisition of a mesenchymal phenotype. In breast cancer, the EMT state has been associated with cancer stem cell properties including expression of the stem cell-associated CD44⁺/CD24^-/low antigenic profile, self-renewal capabilities and resistance to conventional therapies. Intriguingly, EMT features are also associated with stem cells isolated from the normal mouse mammary gland and human breast reduction tissues as well as the highly aggressive metaplastic and claudin-low breast tumor subtypes. This has implications for the origin of these breast tumors as it remains unclear whether they derive from cells that have undergone EMT or whether they represent an expansion of a pre-existing stem cell population that expresses EMT-associated markers to begin with. In the present review, we consider the current evidence connecting EMT and stem cell attributes and discuss the ramifications of these newly recognized links for our understanding of the emergence of distinct breast cancer subtypes and breast cancer progression.     

上皮-间质转化与乳腺癌

上皮-间质转化(EMT)使原发癌细胞获得间质特征,并且在转移部位上皮再生形成继发性肿瘤.该过程参与乳腺癌的浸润和转移,有可能影响疗效.乳腺癌细胞的一系列标记蛋白可监测转录调节和表观遗传调控引起的细胞学行为的特征性改变,并能够提供预测依据和治疗靶点.     

上皮-间质转化与胃癌

上皮-间质转化（EMT）是上皮细胞向间质细胞转化的现象。近年来发现EMT可以通过多种机制影响胃癌的发生发展,促进肿瘤细胞迁移和侵袭。EMT的发生涉及多个信号通路,与微小RNA、幽门螺杆菌、转录因子等有关,其有望成为治疗侵袭性胃癌的新靶点。     

Epithelial-mesenchymal transition in breast cancer lines is mediated through PDGF-D released by tissue-resident stem cells

Epithelial-mesenchymal transition (EMT) generates tumor cells with stem cell properties. The aim of our study was to investigate the effects of adipose tissue-derived stem cells (ASCs) on EMT of cancer cells and to further investigate the mechanisms involved. We demonstrate that conditioned medium from ASCs induces breast cancer cells (4T1) to express mesenchymal markers such as fibronectin, alpha smooth muscle actin and vimentin. Flow cytometry analyses show that ASC-conditioned medium promotes the expansion of CD44high/CD24low cancer stem cells. Soft agar assays using T47D, BT474 and MCF-7 breast cancer cells reveals that ASC conditioned medium promotes the anchorage-independent growth of cancer cells. These effects were inhibited by a neutralizing antibody against platelet-derived growth factor-D (PDGF-D). Furthermore, PDGF-D treated breast cancer cells grow faster in a mouse model, and this effect could be neutralized by a PDGF antibody. In conclusion, our data show that tissue-resident stem cells interact with the cancer microenvironment via PDGF-D, induce EMT in the cancer cells in a paracrine fashion, thereby increasing the number of cancer stem cells and increase tumor growth in a PDGF dependent manner. Our findings shed new light on mechanisms where local tissue-resident stem cells are able to promote the growth of breast cancer cells. Possibly this could open up a novel selective therapeutic strategy targeting EMT pathways and the specific communication between tissue-resident normal stem cell and cancer stem cells, assuming that the blockage of PDGF-D pathways is critical for tumor growth but would not affect normal tissue homeostasis.     

上皮-间质转化与肿瘤耐药性的研究进展

上皮-间质转化（EMT）是上皮细胞表型向间质细胞表型转变的过程,在肿瘤发生及其演变中发挥着重要的作用。近期研究表明,EMT在多种肿瘤的化疗耐药中发挥重要作用,而化疗药物也能增强肿瘤的恶性程度包括诱导EMT表型的产生。本文结合国内外最新报道,对EMT与肿瘤耐药关系的研究进展进行综述。      

EMT经p38-MAPK调节乳腺癌MCF-7细胞P-gp介导的多药耐药

摘 要　目的：探讨乳腺癌细胞中上皮间质转化（epithelial-mesenchymal transition, EMT）与P-糖蛋白（P-glucoprotein, P-gp）介导的多药耐药（multidrug resistance, MDR）的关系及其可能的机制。方法：将携Snail基因的真核表达载体pcDNA-Snail转染人乳腺癌细胞MCF-7,用多柔比星（doxorubicin, DOX）诱导各组细胞耐药。免疫细胞荧光检测上皮标志物E-钙黏素（E-cadherin）、间质标志物波形蛋白（vimentin）以及P-gp的表达,MTT检测耐药细胞的增殖,RT-PCR检测Snail、MDR1、p38-MAPK mRNA的表达。结果：细胞免疫荧光显示,转染pcDNA-Snail载体后,MCF-7细胞发生EMT,E-cadherin表达显著降低,vimentin表达显著升高;P-gp在发生EMT的MCF-7细胞中表达显著升高。经DOX诱导,MCF-7/Snail细胞的耐药能力较MCF-7/DOX细胞显著增强（P<0.05）。RT-PCR显示,MCF-7细胞发生EMT后,p38-MAPK表达显著升高（P<0.05）,MDR1表达较亲本细胞明显升高（P<0.01）。结论：MCF-7细胞发生EMT后,可能通过p38-MAPK引发P-gp介导的MDR。     

上皮间质转化和肿瘤干细胞

最近,两个新的概念出现在肿瘤生物学中：上皮间质转化（epitheilal-mesenchymal transition,EMT）和肿瘤干细胞（cancer stem cells,CSCs）。EMT不仅赋予细胞迁移和侵袭特征,还可使肿瘤细胞获得自我更新能力而具有干细胞的特性,从而促进CSCs的产生。本文讨论EMT和CSCs之间的联系、EMT获得干细胞特征促进CSCs产生、EMT是形成CSCs的重要环节及二者在干细胞巢中的转化,并分析影响EMT和CSCs的因素。研究EMT在肿瘤发生中的作用,与CSCs理论相融合,从而可能发现新的肿瘤靶向治疗。     

上皮间质转化和肿瘤干细胞

最近,两个新的概念出现在肿瘤生物学中:上皮间质转化(epitheilal-mesenchymal transition,EMT)和肿瘤干细胞(cancer stem cells,CSCs)。EMT不仅赋予细胞迁移和侵袭特征,还可使肿瘤细胞获得自我更新能力而具有干细胞的特性,从而促进CSCs的产生。本文讨论EMT和CSCs之间的联系、EMT获得干细胞特征促进CSCs产生、EMT是形成CSCs的重要环节及二者在干细胞巢中的转化,并分析影响EMT和CSCs的因素。研究EMT在肿瘤发生中的作用,与CSCs理论相融合,从而可能发现新的肿瘤靶向治疗。     

Epithelial-mesenchymal transition leads to crizotinib resistance in H2228 lung cancer cells with EML4-ALK translocation

Epithelial-mesenchymal transition (EMT) is associated with reduced sensitivity to many chemotherapeutic drugs, including EGFR tyrosine kinase inhibitors. Here, we investigated if this reduced sensitivity also contributes to resistance to crizotinib, an ALK inhibitor of lung cancer that exhibits the EML4-ALK translocation. We established a crizotinib-resistant subline (H2228/CR), which was derived from the parental H2228 cell line by long-term exposure to increasing concentrations of crizotinib. Characteristics associated with EMT, including morphology, EMT marker proteins, and cellular mobility, were analyzed. Compared with H2228 cells, the growth of H2228/CR cells was independent of EML4-ALK, and H2228/CR cells showed cross-resistance to TAE-684 (a second-generation ALK inhibitor). Phenotypic changes to the spindle-cell shape were noted in H2228/CR cells, which were accompanied by a decrease in E-cadherin and increase in vimentin and AXL. In addition, H2228/CR cells showed increased secretion and expression of TGF-β1. Invasion and migration capabilities were dramatically increased in H2228/CR cells. Applying TGF-β1 treatment to parental H2228 cells for 72 h induced reversible EMT, leading to crizotinib resistance, but this was reversed by the removal of TGF-β1. Suppression of vimentin in H2228/CR cells by siRNA treatment restored sensitivity to crizotinib. Furthermore, these resistant cells remained highly sensitive to the Hsp90 inhibitors, similar to the parental H2228 cells. In conclusion, we suggest EMT is possibly involved in acquired resistance to crizotinib, and that HSP90 inhibitors could be a promising option for the treatment of EMT.     

Breast cancer stem cells: treatment resistance and therapeutic opportunities

The clinical and pathologic heterogeneity of human breast cancer has long been recognized. Now, molecular profiling has enriched our understanding of breast cancer heterogeneity and yielded new prognostic and predictive information. Despite recent therapeutic advances, including the HER2-specific agent, trastuzumab, locoregional and systemic disease recurrence remain an ever-present threat to the health and well being of breast cancer survivors. By definition, disease recurrence originates from residual treatment-resistant cells, which regenerate at least the initial breast cancer phenotype. The discovery of the normal breast stem cell has re-ignited interest in the identity and properties of breast cancer stem-like cells and the relationship of these cells to the repopulating ability of treatment-resistant cells. The cancer stem cell model of breast cancer development contrasts with the clonal evolution model, whereas the mixed model draws on features of both. Although the origin and identity of breast cancer stem-like cells is contentious, treatment-resistant cells survive and propagate only because aberrant and potentially druggable signaling pathways are recruited. As a means to increase the rates of breast cancer cure, several approaches to specific targeting of the treatment-resistant cell population exist and include methods for addressing the problem of radioresistance in particular.     

Epithelial-mesenchymal transition and stemness features in circulating tumor cells from breast cancer patients

Currently used methods to detect and enumerate circulating tumor cells (CTCs) rely on the expression of the epithelial cell adhesion molecule (EpCAM) and cytokeratins. This selection may exclude cells that have undergone intrinsic modifications of their phenotype, as epithelial-mesenchymal transition (EMT). Aim of the study was to investigate the expression of EMT and stemness markers in CTCs from breast cancer patients in all stages of disease. 92 female breast cancer patients were enrolled. CTCs were isolated by CELLection Dynabeads coated with the monoclonal antibody toward EpCam. Samples found positive for CTCs presence (CD45-/CK+) were evaluated for the expression of ER alpha, HER2, ALDH1, vimentin, and fibronectin. Samples negative for CTCs presence (CD45-/CK-) were also evaluated for the expression of vimentin and fibronectin, used as markers of EMT. CTCs were found in 66% of patients. The distribution of CTCs presence according to stage and grade of disease was found statistically significant. The expression of ALDH1 on CTCs was found to correlate to stage of disease and to the expression of vimentin and fibronectin. In 34% of patients, we detected cells with negative CK/CD45 expression but positive expression of vimentin and fibronectin. There is an urgent need for optimizing CTCs detection methods through the inclusion of EMT markers. The detection of cells in mesenchymal transition, retaining EMT and stemness features, may contribute to discover additional therapeutic targets useful to eradicate micrometastatic disease in breast cancer.     

上皮间质转化与恶性肿瘤转移

Epithelial-mesenchymal transition (EMT) is initially considered as a physiological phenomenon during the embryogenesis of mammals, as well as a basic biological event maintaining the stability of the vital body. Recent researches indicated that EMT plays a critical role in various tumors progression, through which epithelial cancers invade and metastasize. The cell characteristics are changed during EMT, in which the cells lose cell-cell and cell-matrix interactions and apical polarity, reorganize their cytoskeleton, and become isolated, motile, as well as resistant to anoikis, then become spindle-shaped mesenchymal cells. This review lays emphasis on studying the cell morphogenesis, makers and molecular mechanism regulation about EMT, discussing the relationship between the EMT and the cancer development and metastasis.     

Epithelial-mesenchymal transition and breast cancer: role, molecular mechanisms and clinical impact

Epithelial-mesenchymal transition (EMT) is defined by the loss of epithelial characteristics and the acquisition of a mesenchymal phenotype. In this process, cells acquire molecular alterations that facilitate dysfunctional cell-cell adhesive interactions and junctions. These processes may promote cancer cell progression and invasion into the surrounding microenvironment. Such transformation has implications in progression of breast carcinoma to metastasis, and increasing evidences support most tumors contain a subpopulation of cells with stem-like and mesenchymal features that is resistant to chemotherapy. This review focuses on the physiological and pathological role of EMT process, its molecular related network, its putative role in the metastatic process and its implications in response/resistance to the current and/or new approaching drugs in the clinical management of breast cancer.