Epithelial-Mesenchymal Transition Directs Stem Cell Polarity via Regulation of Mitofusin

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肿瘤微环境中上皮–间质转化与肿瘤干细胞的调控

肿瘤微环境是一个复杂的组织样结构,具有丰富的表型和功能异质性。不同浓度的趋化因子、细胞因子与组成肿瘤微环境的细胞间相互作用,可激活上皮–间质转化(epithelial-mesenchymal transition,EMT)相关的信号通路及控制肿瘤干细胞(cancer stem cells,CSCs)的生成。EMT的异常激活会促进肿瘤细胞的可塑性,赋予上皮细胞间充质特性,并与癌细胞获得侵袭性的特征密切相关。CSCs是一类具有高致瘤潜能的细胞群,其能很容易地适应周围环境的变化,与肿瘤内其他细胞相比具有较强的抗药性。该文对肿瘤微环境中EMT与CSC的作用机制及相关信号通路的研究进展进行综述。     

SALL4 as an Epithelial-Mesenchymal Transition and Drug Resistance Inducer through the Regulation of c-Myc in Endometrial Cancer

SALL4 plays important roles in the development and progression of many cancers. However, the role and molecular mechanism of SALL4 in endometrial cancer remain elusive. In the present research, we have demonstrated that the expression of SALL4 was upregulated in endometrial cancer and correlated positively with tumor stage, metastases and poor survival of patients. The overexpression of SALL4 promoted the invasiveness in endometrial cancer cells, as indicated by the upregulation of mesenchymal cell marker N-cadherin and downregulation of the epithelial marker E-cadherin, and invasion assays in vitro. Additionally, there was also an increase in drug resistance in these cell models due to the upregulation of ATP-binding cassette multidrug transporter ABCB1 expression. Moreover, we also found that ABCB1 was critical for SALL4-induced drug resistance. In contrast, SALL4 knockdown restored drug sensitivity, reversed EMT, diminished cell metastasis and suppressed the downregulation of E-cadherin and the upregulation of N-cadherin and ABCB1. Furthermore, we showed that SALL4 upregulated c-Myc expression and c-Myc was a direct target for SALL4 by ChIP assay, depletion of c-Myc with siRNA abolished the SALL4-induced downregulation of E-cadherin, upregulation of N-cadherin and ABCB1, suggesting that c-Myc was a downstream target for SALL4 and required for SALL4-induced EMT, invasion and drugs resistance in endometrial cancer cells. These results indicated that SALL4 could induce EMT and resistance to antineoplastic drugs through the regulation of c-Myc. SALL4 and c-Myc may be novel therapeutic targets for endometrial cancer.     

Fatty Acid Synthase Mediates the Epithelial-Mesenchymal Transition of Breast Cancer Cells

This study aimed to investigate the role of fatty acid synthase (FASN) in the epithelial-mesenchymal transition (EMT) of breast cancer cells. MCF-7 cells and MCF-7 cells overexpressing mitogen-activated protein kinase 5 (MCF-7-MEK5) were used in this study. MCF-7-MEK5 cells showed stable EMT characterized by increased vimentin and decreased E-cadherin expression. An In vivo animal model was established using the orthotopic injection of MCF-7 or MCF-7-MEK5 cells. Real-time quantitative PCR and western blotting were used to detect the expression levels of FASN and its downstream proteins liver fatty acid-binding protein (L-FABP) and VEGF/VEGFR-2 in both in vitro and in vivo models (nude mouse tumor tissues). In MCF-7-MEK5 cells, significantly increased expression of FASN was associated with increased levels of L-FABP and VEGF/VEGFR-2. Cerulenin inhibited MCF-7-MEK5 cell migration and EMT, and reduced FASN expression and down-stream proteins L-FABP, VEGF, and VEGFR-2. MCF-7-MEK5 cells showed higher sensitivity to Cerulenin than MCF-7 cells. Immunofluorescence revealed an increase of co-localization of FASN with VEGF on the cell membrane and with L-FABP within MCF-7-MEK5 cells. Immunohistochemistry further showed that increased percentage of FASN-positive cells in the tumor tissue was associated with increased percentages of L-FABP- and VEGF-positive cells and the Cerulenin treatment could reverse the effect. Altogether, our results suggest that FASN is essential to EMT possibly through regulating L-FABP, VEGF and VEGFR-2. This study provides a theoretical basis and potential strategy for effective suppression of malignant cells with EMT.     

间质-上皮转化在肿瘤转移中的作用

肿瘤转移是一个多步骤、多因素参与的复杂过程,是目前临床上绝大多数肿瘤患者的致死因素.上皮-间质转化(epithelial-mesenchymal transition, EMT)过程已被证实可促使肿瘤细胞发生转移.近年来许多研究表明,间质-上皮转化(mesenchymal-epithelial transition, MET)即EMT的逆过程,与肿瘤也密切相关,特别是肿瘤转移即形成继发性的肿瘤转移灶.深入研究肿瘤MET有望为肿瘤转移的预防和诊治提供新思路.     

Bmi1 Essentially Mediates Podocalyxin-Enhanced Cisplatin Chemoresistance in Oral Tongue Squamous Cell Carcinoma

Oral tongue squamous cell carcinoma (OTSCC) is one of the most common head and neck cancers. Innate or acquired resistance to cisplatin, a standard chemotherapy agent for OTSCC, is common in patients with OTSCC. Understanding the molecular basis for cisplatin chemoresistance in OTSCC cells may serve as a basis for identification of novel therapeutic targets. Podocalyxin (PODXL) has been found critical for malignant progression in a variety of cancers. Bmi1 has recently been found to induce cell apoptosis and cisplatin chemosensitivity in OTSCC cells. In this study, we explored the interaction between PODXL and Bmi1 in OTSCC cells, and assessed its impact on OTSCC cell chemoresistance to cisplatin. PODXL and/or Bmi1 were stably overexpressed or knocked down in SCC-4 and Tca8113 human OTSCC cells. Overexpression of PODXL in both cell lines markedly elevated the expression level of Bmi1 and the half maximal inhibitory concentration (IC50) of cisplain and reduced cisplatin-induced cell apoptosis, which was abolished by knockdown of Bmi1 or a selective focal adhesion kinase (FAK) inhibitor. On the other hand, knockdown of PODXL significantly decreased the Bmi1 expression level and cisplatin IC50 and increased cisplatin-induced cell apoptosis, which was completely reversed by overexpression of Bmi1. While overexpression and knockdown of PODXL respectively increased and decreased the FAK activity, Bmi1 showed no significant effect on the FAK activity in OTSCC cells. In addition, overexpression of PODXL markedly elevated the stability of Bmi1 mRNA, which was abolished by a selective FAK inhibitor. In conclusion, this study provides the first evidence that PODXL up-regulates the expression level of Bmi1 in OTSCC cells by increasing the stability of Bmi1 mRNA through a FAK-dependent mechanism; this effect leads to enhanced cisplatin chemoresistance in OTSCC cells. This study adds new insights into the molecular mechanisms underlying OTSCC chemoresistance.     

Multi-omics Analysis of Ferroptosis Regulation Patterns and Characterization of Tumor Microenvironment in Patients with Oral Squamous Cell Carcinoma

Ferroptosis is a newly recognized mechanism of regulated cell death. It was reported to be highly associated with immune therapy and chemotherapy. However, its mechanism of regulation in the tumor microenvironment (TME) and influence on oral squamous cell carcinoma (OSCC) therapy are unknown. We identified a ferroptosis-specific gene-expression signature, an FPscore, developed by a principal component analysis (PCA) algorithm to evaluate the ferroptosis regulation patterns of individual tumor. Multi-omics analysis of ferroptosis regulation patterns was conducted. Three distinct ferroptosis regulation subtypes, which linked to outcomes and the clinical relevance of each patient, were established. A high FPscore of patients with OSCC was associated with a favorable prognosis, a ferroptosis-related immune-activation phenotype, potential sensitivities to the chemotherapy and immunotherapy. Importantly, a high FPscore correlated with a low gene copy number burden and high immune checkpoint expressions. We validated the prognostic value of the FPscore using independent immunotherapy and pan-cancer cohorts. Comprehensive evaluation of individual tumors with distinct ferroptosis regulation patterns provides new mechanistic insights, which may be clinically relevant for the application of combination therapies in OSCC.     

CK4基因在喉咽鳞癌中的表达及意义

目的:探讨喉咽鳞癌组织中细胞角蛋白4(CK4)的表达及其临床意义.方法:应用免疫组织化学方法检测60例喉咽鳞癌患者的癌旁正常组织和癌组织标本中CK4的表达.结果:CK4在癌旁正常组织中表达强阳性,在喉咽鳞癌组织中表达下降,其差异有统计学意义(x2=73.594,P＜0.05).与高分化鳞癌相比,CK4在中分化和低分化鳞癌组织中表达均出现明显下降,其差异有统计学意义(F=57.082,P＜0.05).结论:CK4在喉咽鳞癌组织中的低表达对喉咽鳞癌的诊断有一定的临床意义,并有望成为喉咽鳞癌恶性程度的生物学标记物.     

Multi-photon Imaging of Tumor Cell Invasion in an Orthotopic Mouse Model of Oral Squamous Cell Carcinoma

Loco-regional invasion of head and neck cancer is linked to metastatic risk and presents a difficult challenge in designing and implementing patient management strategies. Orthotopic mouse models of oral cancer have been developed to facilitate the study of factors that impact invasion and serve as model system for evaluating anti-tumor therapeutics. In these systems, visualization of disseminated tumor cells within oral cavity tissues has typically been conducted by either conventional histology or with in vivo bioluminescent methods. A primary drawback of these techniques is the inherent inability to accurately visualize and quantify early tumor cell invasion arising from the primary site in three dimensions. Here we describe a protocol that combines an established model for squamous cell carcinoma of the tongue (SCOT) with two-photon imaging to allow multi-vectorial visualization of lingual tumor spread. The OSC-19 head and neck tumor cell line was stably engineered to express the F-actin binding peptide LifeAct fused to the mCherry fluorescent protein (LifeAct-mCherry). Fox1^nu/nu mice injected with these cells reliably form tumors that allow the tongue to be visualized by ex-vivo application of two-photon microscopy. This technique allows for the orthotopic visualization of the tumor mass and locally invading cells in excised tongues without disruption of the regional tumor microenvironment. In addition, this system allows for the quantification of tumor cell invasion by calculating distances that invaded cells move from the primary tumor site. Overall this procedure provides an enhanced model system for analyzing factors that contribute to SCOT invasion and therapeutic treatments tailored to prevent local invasion and distant metastatic spread. This method also has the potential to be ultimately combined with other imaging modalities in an in vivo setting.     

原发性口腔鳞癌组织及血清中内皮抑素表达的意义

目的:探讨原发性口腔鳞癌患者组织和血清中内皮抑素表达及与肿瘤分期、分级的关系。方法:采用免疫组化方法检测36例口腔鳞癌和12例正常口腔粘膜组织中内皮抑素表达情况。ELISA法检测36例口腔鳞癌患者术前血清内皮抑素水平,14例健康者血清做对照。结果:内皮抑素主要见于肿瘤组织细胞质。正常口腔粘膜中内皮抑素表达率为7.15%,口腔鳞癌组织中内皮抑素阳性率为76.44%,其中G1、G2、G3级阳性率分别为47.21%、79.17%、90.90%,病理分级间比较差异有统计学意义(P<0.05)。口腔鳞癌患者血清中内皮抑素水平(49.62±1.72)ng/mL显著高于健康对照者(5.60±0.37)ng/mL(P<0.05),TNM分期III、IV期肿瘤患者血清内皮抑素水平显著高于I和II期(P<0.05)。结论:口腔鳞癌患者组织和血清中内皮抑素表达显著升高,并与肿瘤分期、分级相关,检测内皮抑素表达有助于判断口腔鳞癌恶性程度。     

原发性口腔鳞癌组织及血清中内皮抑素表达的意义

目的：探讨原发性口腔鳞癌患者组织和血清中内皮抑素表达及与肿瘤分期、分级的关系。方法：采用免疫组化方法检测36例口腔鳞癌和12例正常口腔粘膜组织中内皮抑素表达情况。ELISA法检测36例口腔鳞癌患者术前血清内皮抑素水平,14例健康者血清做对照。结果：内皮抑素主要见于肿瘤组织细胞质。正常口腔粘膜中内皮抑素表达率为7.15%,口腔鳞癌组织中内皮抑素阳性率为76.44%,其中G1、G2、G3级阳性率分别为47.21%、79.17%、90.90%,病理分级间比较差异有统计学意义（P〈0.05）。口腔鳞癌患者血清中内皮抑素水平（49.62±1.72）ng/mL显著高于健康对照者（5.60±0.37）ng/mL（P〈0.05）,TNM分期III、IV期肿瘤患者血清内皮抑素水平显著高于I和II期（P〈0.05）。结论：口腔鳞癌患者组织和血清中内皮抑素表达显著升高,并与肿瘤分期、分级相关,检测内皮抑素表达有助于判断口腔鳞癌恶性程度。     

食管鳞癌MLH1基因改变及其与微卫星不稳定的关系

MLH1是位于3p21．3上的一个DNA错配修复基因,其异常与多种肿瘤相关。为探索食管鳞癌中MLH1基因改变及其与微卫星不稳定(MSI)的关联情况,采用微卫星分析和RT—PCR方法检测了14个微卫星标志在食管癌中的状况及MLH1转录水平的表达,发现35％的食管癌出现至少一个微卫星的不稳定,66．7％的肿瘤在MLH1基因内标志D3S1611位点表现为杂合性丢失,但是MLH1没有明显的mRNA表达下调。MSI与食管癌分期、分级、淋巴结转移、患者年龄和性别等参数及MLH1基因杂合性丢失(LOH)之间无统计学意义的相关性。这些结果表明：食管癌中MLH1存在较高频率的等位基因丢失,但其mRNA表达水平并无明显异常;所测微卫星标志的不稳定是食管癌的频发事件,与MLH1基因LOH不存在必然联系。     

转录因子KLF5调控宫颈癌细胞上皮-间充质转化的分子机制

上皮-间充质转化(epithelial-mesenchymal transition, EMT)是上皮细胞来源的恶性肿瘤细胞获得迁移和侵袭能力的重要生物学过程。为了探究Krüppel样因子5 (Krüppel-like factor 5, KLF5)调控宫颈癌细胞发生EMT过程的分子机制,首先在宫颈癌HeLa细胞瞬时转染Flag-KLF5质粒进行KLF5过表达,并通过MTT法、细胞划痕和Transwell实验证实, KLF5可以显著地抑制HeLa细胞的侵袭和迁移能力。然后采用Western-blot和实时定量PCR技术检测HeLa细胞中EMT相关基因的表达水平,结果显示E-cadherin表达升高, N-cadherin和MMP9表达降低;而且, E-cadherin基因的上游调控因子如SNAI1、SLUG、ZEB1/2和TWIST1等的m RNA表达下降。进一步开展对比研究,在Si Ha细胞中用si RNA沉默KLF5基因,再次验证了KLF5对EMT相关基因表达水平的影响。随后构建不同长度的SNAI1启动子截短体,用荧光素酶报告基因实验检测KLF5对SNAI1启动子活性的影响,结果显示KLF5可以抑制SNAI1启动子区域的活性,并且在HeLa细胞中过表达SNAI1基因后,可显著地促进细胞的EMT过程。以上结果表明, KLF5可通过调控SNAI1基因的表达来调节宫颈癌细胞的EMT过程,进而抑制宫颈癌细胞的迁移和侵袭能力。