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本帖最后由 饶冠华 于 2010-8-18 09:20 编辑
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; V) p) I' U g, R6 t7 S“了解肿瘤,关注肿瘤干细胞”-第六期:No. 2010-8-(6)
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活动时间:2010-8-16~2010-9-10% J1 y4 a6 {0 i: }% N
: X( B2 {1 S. T; V讨论话题: EMT与肿瘤转移的关系 ; \* m" H X( e+ |' d8 k a& h
1. EMT是什么?
$ ~8 Z7 i/ G! I2. EMT在肿瘤转移中的作用?
5 L3 W5 c. J3 v, h( d3. EMT这个现象到底存不存在?是实验假象还是真实存在?% e/ F+ N0 d2 ~/ @
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+ j! b# b" \: V$ {在讨论这个话题之前,推荐大家先看两篇文献:
: H9 m& G. u6 z0 O1. J Cell Biol. 2006 Mar 27;172(7):973-81.8 V' B/ q2 G/ s) H9 U0 K2 k: O- ^
. ^3 C/ y6 G9 ?# H9 D6 AThe epithelial-mesenchymal transition: new insights in signaling, development, and disease.+ k+ m, ^+ X+ `1 x: h j7 @3 y/ |
Lee JM, Dedhar S, Kalluri R, Thompson EW.
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Department of Biochemistry, Microbiology, and Immunology, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada.
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Abstract
6 t, W" D$ d( Y% l- ?6 yThe conversion of an epithelial cell to a mesenchymal cell is critical to metazoan embryogenesis and a defining structural feature of organ development. Current interest in this process, which is described as an epithelial-mesenchymal transition (EMT), stems from its developmental importance and its involvement in several adult pathologies. Interest and research in EMT are currently at a high level, as seen by the attendance at the recent EMT meeting in Vancouver, Canada (October 1-3, 2005). The meeting, which was hosted by The EMT International Association, was the second international EMT meeting, the first being held in Port Douglas, Queensland, Australia in October 2003. The EMT International Association was formed in 2002 to provide an international body for those interested in EMT and the reverse process, mesenchymal-epithelial transition, and, most importantly, to bring together those working on EMT in development, cancer, fibrosis, and pathology. These themes continued during the recent meeting in Vancouver. Discussion at the Vancouver meeting spanned several areas of research, including signaling pathway activation of EMT and the transcription factors and gene targets involved. Also covered in detail was the basic cell biology of EMT and its role in cancer and fibrosis, as well as the identification of new markers to facilitate the observation of EMT in vivo. This is particularly important because the potential contribution of EMT during neoplasia is the subject of vigorous scientific debate (Tarin, D., E.W. Thompson, and D.F. Newgreen. 2005. Cancer Res. 65:5996-6000; Thompson, E.W., D.F. Newgreen, and D. Tarin. 2005. Cancer Res. 65:5991-5995)., ^2 `6 g/ ^3 E' `
. t1 n+ E/ |+ Q L- hPMID: 16567498 ' r% g/ t: ^& o2 c0 d6 I
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( Z. Z1 \7 @6 j& Y L. e& f* k" Z0 X+ A* j2. Cancer Res. 2009 Sep 15;69(18):7135-9. Epub 2009 Sep 8.
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Epithelial-mesenchymal transition and cell cooperativity in metastasis.4 k4 J1 A3 w8 r# y; Z Q: B$ A
Tsuji T, Ibaragi S, Hu GF.
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( B% r1 d7 A$ V8 [# v/ SDepartment of Radiation Oncology, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA.' Y( e: \$ E7 b, G
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Abstract
) s3 A9 a" Y) Y5 `7 XThe role of epithelial-mesenchymal transition (EMT) in metastasis remains controversial. EMT has been postulated as an absolute requirement for tumor invasion and metastasis. Three different models including incomplete EMT, mesenchymal-epithelial transition (MET), and collective migration have been proposed for the role of EMT in cancer invasion and metastasis. However, skepticism remains about whether EMT truly occurs during cancer progression, and if it does, whether it plays an indispensible role in metastasis. Our recent findings suggest that EMT cells are responsible for degrading the surrounding matrix to enable invasion and intravasation of both EMT and non-EMT cells. Only non-EMT cells that have entered the blood stream are able to re-establish colonies in the secondary sites. Here, we discuss an alternative model for the role of EMT in cancer metastasis in which EMT and non-EMT cells cooperate to complete the entire process of spontaneous metastasis.
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9 h7 w8 f& }9 a$ S% h8 ~1. 关于epithelial cells 和 mesenchymal cells 的特点,以及EMT一些性质。 请参考以下PDF文档
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( C- ^9 M' N: p# `: ?0 i2. 关于EMT,看到版面上有些战友对EMT嗤之以鼻,甚至很不屑,我觉得,怎么说呢...有些可惜...EMT在体内环境下,是有发生的,具体可以看以下图片。
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/ W& W! o2 L2 u9 f4 x! v目前对EMT争议比较大的就是EMT在肿瘤转移过程中到底起什么作用?3 y8 H. X C+ ]( G
& [- l; X5 }3 W. T& J关于这点我想先看看各位战友看完这两篇文献之后的讨论情况,再发表评论。关于我对EMT的观点,将会在48小时之内补充在本帖下面。希望大家多多参与讨论。
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下面说说我自己关于EMT的观点吧:; B! i" X9 ]- }" x9 q$ Y
1. 关于EMT存不存在,我的观点是,EMT在in vivo 的环境下是绝对存在的。并且在肿瘤转移过程中扮演着很重要的角色。/ v3 K, N9 k) X7 N% f8 H3 A
2. 那么EMT在肿瘤转移过程中到底起着什么样的作用呢?我想这也是大家关注的重点吧。& `) j2 a& [/ S/ T
那么简单地说一下自己的看法:EMT在肿瘤转移过程中最大贡献之处,如“文献2”中所讲,是能够分泌一些蛋白酶水解基底膜以及肿瘤外围的胞外基质,为后面其它肿瘤细胞的转移侵袭进入血液循环系统打通通道。另外,EMT转变之后的肿瘤细胞迁移能力变强,这样更加方便肿瘤细胞逃逸原位环境。
, N3 I! t7 M, [3 \/ R% ]3. 关于EMT,这里需要特别强调的是(相信很多人在这个方面都存在误解),EMT在大部分情况下,都是一个可逆的变化过程。所谓可逆,就是一旦周围环境(microenvironment)发生变化,那么EMT的肿瘤细胞就可能发生MET回复其上皮细胞的特点。EMT只是一个临时的状态,而不是肿瘤细胞发生的一个恒定变化。这也是为什么战友marrowstem站在临床的角度说EMT似乎不是那么真实的原因。在肿瘤微环境中,包括tumor stroma,很多因子以及stroma cell都能促进肿瘤细胞发生EMT转变,还有缺氧环境,而一旦把这些外界因素从肿瘤细胞周边去除之后,肿瘤细胞又很快会恢复成上皮样细胞。发生EMT的细胞并不表示恶性程度的改变,只是从一种状态转变成另外一种状态。4 X6 Y) C/ k/ e4 W- ^, i8 u2 c: C
因此整个过程我们可以理解成这样:; J* t/ R% U2 M) o! e6 h
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