上皮-间质转化及其调控基因Snail在肿瘤侵袭转移中的作用

上皮间质转化(EMT)和锌指转录因子Snail在肿瘤的侵袭和远处转移过程中起重要作用。笔者就两者在肿瘤侵袭转移中的作用结合文献进行综述。     

肿瘤骨转移机制研究的新进展

肿瘤的骨转移由非常复杂的事件链交织而成，现代“土壤与种子”学说认为，上皮性实体肿瘤在向远处转移时，首先突破血管壁，经过上皮-间质化，在血小板的包被下，受选择素和趋化因子的作用，通过解剖捷径，定植于远隔部位，继发成骨和破骨作用改变局部微环境，为新的转移创造条件。

     

TGF-&beta|介导的上皮间质转化

上皮间质转化（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,在EMT的形成机制中,转化生长因子β（TGF-β）被认为起了关键性作用。笔者就EMT与肿瘤侵袭转移的关系,以及TGF-β介导EMT的相关信号通路进行综述。     

miRNA-639在乳腺癌中表达及其意义

目的：探讨miRNA-639（miR-639）在乳腺癌中的表达及其与乳腺癌生长、侵袭及转移的关系。 方法：采用荧光定量PCR方法检测miR-639在60例乳腺癌组织（转移性乳腺癌30例,非转移性30例）与30例癌旁组织、以及人乳腺癌MD231细胞与MCF-7细胞中的表达;分析miR-639表达水平与乳腺癌患者临床病理特征关系;分别通过CCK-8实验、细胞划痕实验、Boyden小室实验检测miR-639在乳腺癌细胞增殖、迁移和侵袭中的作用。 结果：miR-639的表达水平在乳腺癌组织中明显高于癌旁组织、在转移性乳腺癌组织中明显高于非转移性乳腺癌组织、在高侵袭性MD231细胞中明显高于低侵袭性MCF-7细胞,差异均有统计学意义（均P<0.05）。在各项临床病理因素中,miR-639的表达与仅乳腺癌患者的M分期有关（P<0.01）。转染miR-639抑制物后,MD231细胞的增殖、迁移和侵袭能力明显降低,而转染miR-639后,MCF-7细胞的增殖、迁移和侵袭能力明显升高（均P<0.05）。 结论：miR-639在乳腺癌中表达升高,且乳腺癌的增殖、迁移和侵袭能力随miR-639的表达水平升高而增加。

     

肿瘤起始细胞及上皮-间质转化在肿瘤转移及耐药中的作用

目的总结肿瘤起始细胞(tumor initiating Cells,TICs)和上皮-间质转化(epithelial-mesenchymal transition,EMT)及其在肿瘤转移和耐药中的研究现状。方法检索近年来国内外有关TICs和EMT及其与肿瘤转移和耐药关系的文献并做综述。结果 TICs是肿瘤细胞中一小群具有自我更新、高度增殖及多向分化能力的细胞,表达多种表面标志物,如CD133、CD44等,在肿瘤的侵袭、转移和耐药中起着重要的作用。EMT是肿瘤上皮细胞失去极性转变为间质细胞的一种现象,常见于胚胎发育及组织修复,能够促进肿瘤的侵袭、转移以及逃避宿主的免疫反应,EMT可能是TICs所致肿瘤转移和复发的根源。靶向TICs或EMT的治疗可能有效预防肿瘤的复发及改善患者的预后。结论 EMT是TICs致肿瘤转移及耐药的重要机理,对于TICs和EMT的研究可用于探索更有效的针对肿瘤的靶向治疗策略。     

肝内胆管癌根治性切除术后肿瘤复发转移的预后因素分析

目的：分析肝内胆管癌（IHCC）患者根治性切除术后肿瘤复发转移的危险因素。 方法：收集2002年1月—2008年5月行根治性切除手术治疗的125例IHCC患者的临床病理资料,分析全组患者术后无瘤生存率以及影响术后无瘤生存的不良预后因素。同时分析CA19-9水平与IHCC患者临床病理因素的关系。 结果：截至2013年5月,全组患者随访率为81%,中位随访时间30个月,109例患者出现肿瘤复发或转移。全组患者1、3、5年无瘤生存率分别为61.6%、27.2%、12.8%。多因素分析显示淋巴结转移（RR=3.990,95% CI=2.383~6.679,P<0.001）,肿瘤直径>5 cm（RR=1.78,95% CI=1.190~2.663,P=0.005）,CA19-9>200 U/mL（RR=1.734,95% CI=1.138~2.642,P=0.01）和多发肿瘤（RR=1.77,95% CI=1.114~2.812,P=0.016）是根治性切除术后影响肿瘤复发转移的独立危险因素。CA19-9浓度与淋巴结转移率密切相关（OR=3.208,95% CI=1.276~8.067,P=0.013）;CA19-9水平预测淋巴结转移的曲线下面积（AUC）达到0.696,灵敏度和特异度分别为75.0%和63.0%。 结论：淋巴结转移、肿瘤直径>5 cm、CA19-9>200 U/mL和多发肿瘤是IHCC患者根治术后复发转移的不良预后因素,且术前高CA19-9水平与淋巴结转移密切相关。

     

上皮间质转化与肿瘤转移研究进展

上皮细胞间质转化是一种基本的生理病理变化,其在胚胎发育、慢性炎症、纤维化和肿瘤浸润转移中发挥重要作用。近年来,人们发现EMT与肿瘤的发生及转移可能存在关联,使其迅速成为肿瘤研究的焦点。对于EMT的研究不但能进一步了解其影响肿瘤的机制,而且可促进EMT生物标记物及靶向治疗的研究,这对侵袭性肿瘤的诊治具有重大意义。1 EMT概述     

腹腔镜胃腔外楔形切除术治疗胃间质瘤的疗效：附49例报告

目的：探讨腹腔镜胃腔外楔形切除（ELWR）手术治疗胃间质瘤的可行性与安全性,并评估其肿瘤疗效及相关预后。 方法：选择2005年3月—2012年9月ELWR手术治疗的49例胃间质瘤患者作为研究对象,患者术后均经病理诊断及CD117确诊。分别对患者的临床资料、围手术期情况及患者的长期随访结果进行分析。 结果：患者年龄为（57.1±16.3）岁,其中女性25例。大多数肿块位于胃底部,且肿瘤大小（4.1±2.0）cm, 30例（61.2%）处于极低或低危险度,仅2例为高危险度;除有23例（46.9%）出现腹痛、腹胀外,其余各例未见异常表现;手术时间为（101.9±15.4）min,无中转开腹手术、再次手术或严重手术并发症发生;在平均52个月（10~99个月）的随访中,分别有4例出现复发,2例出现转移并死亡,且经COX回归分析发现肿瘤的危险度分级是其预后的影响因素（P<0.05）。 结论：对胃间质瘤患者施行ELWR手术有效、安全、微创,且结合术后靶向治疗具有良好的预后。

     

胰腺内分泌肿瘤的外科治疗

目的:探讨胰腺内分泌肿瘤的临床特点和外科治疗方法。
方法:对收治的胰腺内分泌肿瘤33例患者的临床资料进行回顾性。
结果:33例中胰岛素瘤18例,无功能性胰岛细胞瘤9例,胃泌素瘤4例,胰高血糖素瘤2例。其中29例进行根治行切除,4例因肿瘤无法切除而放弃手术,总手术切除率为87.8%,术后发生胰瘘5例,肠梗阻2例,无住院期间死亡病例。26例平均随访时间为（4.7±3.5）年（9个月至14年）,其中恶性14例患者总的1年和3年生存率为71.4%和50.0%,在随访期间19例良性患者全部存活。
结论:手术切除是胰腺内分泌肿瘤最为理想的治疗方法。术前定性及术中定位尤为重要,术中胰腺探查结合术中B超是定位的关键。选择合适的术式有助于避免术后并发症的发生。

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间质上皮转化促进膀胱肿瘤转移：成纤维细胞生长因子受体-2的作用

上皮细胞间质转化（EMT）可增强细胞的侵袭、迁移能力，促进多种肿瘤的转移，但无法解释肿瘤原发灶和转移灶上皮的相似性。本研究着力于阐明间质细胞上皮转化（MET）在转移灶形成过程中的重要性，采用膀胱癌TSU—Pr1（T24）细胞株接种联合免疫缺陷小鼠，来观察其接种后是否有转移能力的增强。     

Increased CD13 Expression Reduces Reactive Oxygen Species,Promoting Survival of Liver Cancer Stem Cells via an Epithelial–Mesenchymal Transition-like Phenomenon

Background

Recently, it has been reported that a small population of cancer stem cells (CSCs) play a role in resistance to chemotherapy and radiation therapy. We reported that CD13⁺ liver CSCs survive in hypoxic lesions after chemotherapy, presumably through increased expression of CD13/Aminopeptidase N, which is a scavenger enzyme in the reactive oxygen species (ROS) metabolic pathway. On the other hand, the concept of epithelial–mesenchymal transition (EMT) was indicated by a recent study showing an increased plasticity linked to the cellular “stemness” of CSCs.

Methods

To study the relationship between CSCs and EMT, we examined biological characteristics of liver cancer cell lines with EMT by exposing transforming growth factor-β (TGF-β).

Results

We showed that a TGF-β-induced EMT-like phenomenon is associated with increased CD13 expression in liver cancer cells. This phenomenon prevents further increases in the ROS level as well as the induction of apoptosis, promoting the survival of CD13⁺ CSCs, whereas inhibition of CD13 stimulates apoptosis. Immunohistochemical analysis also indicated that after chemotherapy, CD13 was coexpressed with N-cadherin in surviving cancer cells within fibrous capsules. We have demonstrated that CD13 expression plays a role in supporting the survival of CSCs and that there is an EMT-associated reduction in ROS elevation.

Conclusions

This novel and consistent linkage between functional CSC markers and the EMT phenomenon suggests a bona fide candidate for targeted therapy for EMT-mediated invasion and metastasis of liver cancer.

     

Role of microRNAs in the Regulation of Breast Cancer Stem Cells

There is increasing evidence that many human cancers, including breast cancer, are driven and maintained by cancer stem cells (CSCs) which mediate tumor metastasis and contribute to treatment resistance and relapse. Our group was the first to describe “breast cancer stem cells” (BCSCs) characterized by expression of the cell surface markers ESA and CD44 and the absence of expression of the marker CD24. More recently, we have demonstrated that breast cancer cells contain subpopulations with stem cell properties that can be isolated by virtue of their expression of Aldehyde dehydrogenase (ALDH) as assessed by the Aldefluor assay. Interestingly, these markers identify overlapping, but not identical cell populations. Recent studies have suggested similarities between cancer stem cells and the epithelial mesenchymal transition (EMT) state. Our studies suggest that both normal and malignant breast stem cells exist in distinct, inter-convertible states (EMT and MET), the inter-conversion of which is regulated by microRNAs. EMT-like CSCs have a mesenchymal morphology, are largely quiescent, invasive and characterized by expression of the CSC markers CD24^-CD44⁺ and are EpCAM^-CD49f⁺. In contrast, the MET (mesenchymal epithelial transition) state of CSCs is characterized by active self-renewal and expression of the CSC markers ALDH and EpCAM⁺CD49f⁺. A subpopulation of cells expressing both CD24^-CD44⁺ and ALDH may represent cells in transition between these states. This transition is regulated by signals originating in the microenvironment which in turn modulate microRNA networks in the CSC populations. The existence of multiple stem cell states suggests the necessity of developing therapeutic strategies capable of effectively targeting CSCs in all of these states. In addition, since CSC states are regulated by miRNAs, these small non-coding RNAs may be useful therapeutic agents to target CSCs.     

胰腺癌放、化疗抵抗诱导上皮间质转化

目的：探讨对放、化疗抵抗的胰腺癌细胞发生上皮间质转化(EMT)的意义。
方法：采用健择化疗同期进行放疗对多株人胰腺癌细胞系进行干预,持续2周左右,杀死约90%左右的各细胞系细胞,获得放疗、化疗抵抗的胰腺癌细胞。高倍显微镜下观察细胞形态学变化。transwell小室试验检测细胞侵袭力。利用Western-blot检测上皮表型标志物E-cadherin(E-cad)和间质表型标志物波形蛋白(vimentin)的表达。
结果：放、化疗抵抗的胰腺癌细胞发生与EMT相符的形态学改变:细胞呈纺锤体状,极性消失,并出现伪足;放、化疗抵抗的3株胰腺癌细胞侵袭力增强,其穿过小孔的数目增加(均P﹤0.05);E-cad表达下降,vimentin表达上调。
结论：放、化疗抵抗的人胰腺癌细胞发生EMT,其与胰腺癌治疗抵抗有关。     

大肠癌组织中CEA 表达与肝转移的关系

目的：探讨癌胚抗原（CEA）在大肠癌组织中的表达及其与肝转移的关系。 方法：采用免疫组化法分别检测伴肝转移大肠癌的原发灶与肝转移灶、无肝转移大肠癌组织以及正常肠管黏膜组织中CEA的表达,比较CEA在上述4种组织中阳性表达率与表达强度的差异。 结果：伴肝转移大肠癌的原发灶、肝转移灶、无肝转移大肠癌组织中CEA的阳性表达率分别为97.22%、100%、91.67%,均高于正常肠管黏膜组织（19.44%）（均P<0.05）。4种组织之间的CEA表达强度依次为：肝转移灶>伴肝转移大肠癌原发灶>无肝转移大肠癌组织>正常肠管黏膜（均P<0.05）。 结论：大肠癌组织中CEA表达水平可能与其肝转移密切相关;CEA的高表达可能预示大肠癌的肝转移风险增高。

     

VEGF靶向治疗及其生物标志物在晚期结直肠癌中的研究进展

结直肠癌(CRC)是世界范围内癌症发病与致死的主要因素,近几年分子靶向治疗的临床应用为晚期结直肠癌治疗带来了曙光。贝伐珠单抗被批准应用于一线和二线晚期结直肠癌的治疗,促使了以血管内皮生长因子(VEGF)为作用靶点的靶向治疗药物不断涌现,并在临床试验中取得显著疗效。笔者就VEGF靶向治疗及其生物标志物在晚期结直肠癌中的研究进展进行综述。     

Stemming Resistance to HER-2 Targeted Therapy

Although the development of trastuzumab and lapatinib has improved the outlook for women with HER-2 positive breast cancer, resistance to HER-2 targeted therapy is a growing clinical dilemma. Recent evidence indicates that the HER-2 pathway may play an important role in the maintenance of cancer stem cells (CSCs). The success of HER-2 targeted therapies may, in part, be explained by their direct activity against HER-2 positive CSCs. Our understanding of the mechanisms involved in resistance to trastuzumab, including loss or blockade of the trastuzumab binding site, activation of alternative signaling pathways, and induction of epithelial–mesenchymal transition (EMT), suggests that CSCs may be at the root of resistance of HER-2 targeted therapy. A variety of novel HER-2 targeted approaches have demonstrated promising preliminary clinical activity. Future clinical trials should involve the integration of technologies to assess the impact of novel HER-2 targeted therapies on HER-2 positive CSCs.     

Prostate cell cultures as in vitro models for the study of normal stem cells and cancer stem cells

Current existing therapies for prostate cancer eradicate the majority of cells within a tumor. However, most patients with advanced cancer still progress to androgen-independent metastatic disease that remains essentially incurable by current treatment strategies. Recent evidence has shown that cancer stem cells (CSCs) are a subset of the tumor cells that are responsible for initiating and maintaining the disease. Understanding normal stem cells and CSCs may provide insight into the origin of and new therapeutics for prostate cancer. Normal stem cells and CSCs have been identified in prostate tissue by the use of several markers or techniques. Although research on stem cells has been limited by the lack of suitable in vitro systems, recent studies show that not only primary cells but also several established cell lines may exhibit stem cell properties. This review discusses various in vitro culture systems to propagate normal prostate stem cells and prostate CSCs together with molecular markers. These in vitro cell culture models should be useful for elucidating the differentiation of prostatic epithelium and the biological features of prostate cancer.     

多种转移潜能不同的人前列腺癌细胞“上皮细胞间质转化态”特性鉴定及其意义

目的:对多种转移潜能不同的人前列腺癌细胞“上皮细胞间质转化态”(EMT)特性进行鉴定,并从粘附因素和细胞骨架蛋白角度分析其骨转移潜能获得的分子机制。方法:用W estern印迹法鉴定LNCaP及其亚细胞系C4、C4-2和ArCaP亚细胞系IF11、IA8,以及PC-3、Du145等细胞中上皮型钙粘素(E-cadherin)、神经型钙粘素(N-cadherin)和波形纤维蛋白(V im entin)的表达差异情况,并分析其在前列腺癌转移过程中的作用。结果:E-cad-herin在PC-3、LNCaP、C4、C4-2中表达较高,但在Du145、IF11、IA8中表达极低;而V im entin的表达情况恰恰与E-cadherin相反;N-cadherin在IF11、IA8细胞中呈现显著的高表达状态。结论:转移潜能不同的人前列腺癌细胞株之间存在EMT表型的表达差异,其中PC-3、LNCaP、C4、C4-2是未发生EMT改变的细胞,Du145、IF11、IA8却是EMT化的细胞。EMT表型差异蛋白在解释前列腺癌转移机制方面占据着重要地位。     

The Pathophysiology of Epithelial-Mesenchymal Transition Induced by Transforming Growth Factor-β in Normal and Malignant Mammary Epithelial Cells

Epithelial-mesenchymal transition (EMT) is an essential process that drives polarized, immotile mammary epithelial cells (MECs) to acquire apolar, highly migratory fibroblastoid-like features. EMT is an indispensable process that is associated with normal tissue development and organogenesis, as well as with tissue remodeling and wound healing. In stark contrast, inappropriate reactivation of EMT readily contributes to the development of a variety of human pathologies, particularly those associated with tissue fibrosis and cancer cell invasion and metastasis, including that by breast cancer cells. Although metastasis is unequivocally the most lethal aspect of breast cancer and the most prominent feature associated with disease recurrence, the molecular mechanisms whereby EMT mediates the initiation and resolution of breast cancer metastasis remains poorly understood. Transforming growth factor-β (TGF-β) is a multifunctional cytokine that is intimately involved in regulating numerous physiological processes, including cellular differentiation, homeostasis, and EMT. In addition, TGF-β also functions as a powerful tumor suppressor in MECs, whose neoplastic development ultimately converts TGF-β into an oncogenic cytokine in aggressive late-stage mammary tumors. Recent findings have implicated the process of EMT in mediating the functional conversion of TGF-β during breast cancer progression, suggesting that the chemotherapeutic targeting of EMT induced by TGF-β may offer new inroads in ameliorating metastatic disease in breast cancer patients. Here we review the molecular, cellular, and microenvironmental factors that contribute to the pathophysiological activities of TGF-β during its regulation of EMT in normal and malignant MECs.