世界生命科學(xué)前沿動態(tài)周報（八）

（05.10—05.16 / 2010）
美寶國際集團:陶國新 

　　本周動態(tài)包括以下內(nèi)容：卵巢激素孕酮驅(qū)使乳腺干細胞發(fā)生動態(tài)變化； VE琥珀酸酯可明顯抑制腫瘤細胞生長；發(fā)現(xiàn)抑制胃癌的重要基因；細胞與組織療法與臨床應(yīng)用之間的距離；成人口腔黏膜固有層里有一類新干細胞群；老鼠ips細胞12號染色體印跡基因異常沉默。

1. 卵巢激素孕酮驅(qū)使乳腺干細胞發(fā)生動態(tài)變化
【摘要】
　　 2010-5-10 9:22:45 Nature：香港瑪嘉烈醫(yī)院的癌癥研究人員發(fā)現(xiàn)，卵巢激素孕酮在改變?nèi)橄俑杉毎矫娉袚?dān)了重要的角色。老鼠研究表明，在月經(jīng)的下半個周期孕酮分泌會達到峰值，此時干細胞和鄰近細胞開始相互交流，驅(qū)使正常的乳腺干細胞數(shù)量擴增，這就可能導(dǎo)致環(huán)境改變使得癌癥易于發(fā)生。直到現(xiàn)在，普遍觀點認為在成年女性乳房中，乳腺干細胞一般是不活躍的，這項關(guān)于荷爾蒙改變?nèi)橄俑杉毎难芯繛槿橄侔┏跗诘募毎L開啟了新的理解方式，有利于開發(fā)新的干細胞靶向定位方法。這是第一個關(guān)于孕酮驅(qū)使乳腺干細胞發(fā)生動態(tài)變化的證據(jù)，這種激活機制為細胞變化過程的開啟提供了機會，并最終導(dǎo)致乳腺癌的發(fā)生。
【點評】
　　點評：發(fā)現(xiàn)激素對乳腺干細胞的調(diào)節(jié)作用，有助于干細胞生命規(guī)律的研究。
【原文摘錄】
Nature doi:10.1038/nature09091
Progesterone induces adult mammary stem cell expansion
Purna A. Joshi1, Hartland W. Jackson1, Alexander G. Beristain1, Marco A. Di Grappa1, Patricia Mote2, Christine Clarke2, John Stingl3, Paul D. Waterhouse1 & Rama Khokha1
Reproductive history is the strongest risk factor for breast cancer after age, genetics and breast density1, 2. Increased breast cancer risk is entwined with a greater number of ovarian hormone-dependent reproductive cycles, yet the basis for this predisposition is unknown3, 4, 5. Mammary stem cells (MaSCs) are located within a specialized niche in the basal epithelial compartment that is under local and systemic regulation6. The emerging role of MaSCs in cancer initiation warrants the study of ovarian hormones in MaSC homeostasis. Here we show that the MaSC pool increases 14-fold during maximal progesterone levels at the luteal dioestrus phase of the mouse. Stem-cell-enriched CD49fhi cells amplify at dioestrus, or with exogenous progesterone, demonstrating a key role for progesterone in propelling this expansion. In aged mice, CD49fhi cells display stasis upon cessation of the reproductive cycle. Progesterone drives a series of events where luminal cells probably provide Wnt4 and RANKL signals to basal cells which in turn respond by upregulating their cognate receptors, transcriptional targets and cell cycle markers. Our findings uncover a dynamic role for progesterone in activating adult MaSCs within the mammary stem cell niche during the reproductive cycle, where MaSCs are putative targets for cell transformation events leading to breast cancer.

2. VE琥珀酸酯可明顯抑制腫瘤細胞生長
【摘要】 科學(xué)時報 發(fā)布時間：2010-5-14 9:36:19
　　日前，哈爾濱醫(yī)科大學(xué)公共衛(wèi)生學(xué)院教授吳坤指導(dǎo)的課題組在尋找維生素E琥珀酸酯（VES）在腫瘤化學(xué)防治中的作用及信號傳導(dǎo)途徑的研究中發(fā)現(xiàn)，VES能特異性地抑制胃癌細胞的生長和DNA合成，并誘導(dǎo)其發(fā)生細胞凋亡和細胞分化。 課題組建立起小鼠前胃癌模型，經(jīng)口灌胃或經(jīng)腹腔注射VES，結(jié)果表明VES可顯著降低腫瘤的數(shù)量和體積，提高實驗小鼠的免疫功能；與此同時，他們在離體試驗條件下，以人胃癌細胞為靶細胞，觀察VES對其生長抑制情況，結(jié)果也顯示，VES能明顯抑制癌細胞的生長及DNA合成，促進胃癌細胞分化和誘導(dǎo)細胞凋亡，而對正常細胞無不良影響。 吳坤課題組進行細胞和動物實驗，科學(xué)證實了VES確能遏制腫瘤細胞的生長，延長荷瘤小鼠的生存時間。這為今后VES的資源開發(fā)及臨床推廣應(yīng)用奠定了堅實的理論基礎(chǔ)。
【點評】
　　點評：維生素E琥珀酸酯在細胞和動物實驗中顯示的抑制胃癌細胞生長及誘導(dǎo)其分化或凋亡的功能若能在人體上也看得到，就很可能會為其在胃癌的預(yù)防性營養(yǎng)食品中贏來一席之地。

3. 發(fā)現(xiàn)抑制胃癌的重要基因
【摘要】 醫(yī)藥123 2010-5-13 13:47:02
　　上海交通大學(xué)醫(yī)學(xué)院附屬瑞金醫(yī)院專家首次發(fā)現(xiàn)了5號染色體短臂上的同源盒基因IRX1對抑制胃癌細胞具有重要作用，IRX1的活性丟失可導(dǎo)致胃癌細胞增殖與侵襲能力增加。研究人員發(fā)現(xiàn)，通過轉(zhuǎn)基因技術(shù)將該基因?qū)胛赴┘毎?，使IRX1基因活性恢復(fù)后，無論是體外培養(yǎng)的胃癌細胞，還是小鼠活體內(nèi)的腫瘤細胞，其惡性增殖與侵襲能力均受到明顯抑制。 該研究不僅首次提出IRX1基因在胃癌發(fā)生發(fā)展中的抑癌基因作用，還發(fā)現(xiàn)了另外一個重要現(xiàn)象，即：不但胃癌組織中可以檢測到IRX1基因啟動子的高甲基化，在胃癌患者的外周血游離DNA中也可以檢測到IRX1基因的高甲基化。 研究人員表示，此項研究或成為胃癌診斷新型分子標(biāo)志物的重要線索。
【點評】
　　點評：IRX1基因抑制胃癌的作用及其啟動子的高甲基化的規(guī)律使其有助于胃癌的診斷。
【原文摘錄】
Oncogene doi:10.1038/onc.2010.143
Homeobox gene IRX1 is a tumor suppressor gene in gastric carcinoma
X Guo, W Liu, Y Pan, P Ni, J Ji, L Guo, J Zhang, J Wu, J Jiang, X Chen, Q Cai, J Li, J Zhang, Q Gu, B Liu, Z Zhu and Y Yu
The IRX1 tumor suppressor gene is located on 5p15.33, a cancer susceptibility locus. Loss of heterozygosity of 5p15.33 in gastric cancer was identified in our previous work. In this study, we analyzed the molecular features and function of IRX1. We found that IRX1 expression was lost or reduced in gastric cancer. However, no mutations were identified in IRX1-encoding regions. IRX1 transcription was suppressed by hypermethylation, and the expression of IRX1 mRNA was partially restored in gastric cancer cells after 5-Aza-dC treatment. Restoring IRX1 expression in SGC-7901 and NCI-N87 gastric cancer cells inhibited growth, invasion and tumorigenesis in vitro and in vivo. We identified a number of target genes by global microarray analysis after IRX1 transfection combined with real-time PCR and chromatin immunoprecipitation assay. BDKRB2, an angiogenesis-related gene, HIST2H2BE and FGF7, cell proliferation and invasion-related genes, were identified as direct IRX1 target genes. The hypermethylation of IRX1 was not only detected in primary gastric cancer tissues but also in the peripheral blood of gastric cancer patients, suggesting IRX1 could potentially serve as a biomarker for gastric cancer.

4. 細胞與組織療法與臨床應(yīng)用之間的距離
【摘要】
　　細胞與組織療法中細胞的鑒別和定量面臨著很多挑戰(zhàn)，從管理的角度看，這類治療不止必須安全有效還得高質(zhì)量生產(chǎn)以便能按時運送活細胞。盡管無菌試驗適用常規(guī)的生物工藝，細胞與組織療法需要更嚴(yán)格的安全測試，特別是與使用動物制品、免疫反應(yīng)和長時間培養(yǎng)導(dǎo)致的潛在不穩(wěn)定性有關(guān)時。而且，鑒于其無限生長的潛力，計劃將人類胚胎干細胞用于治療的細胞生產(chǎn)者需要更加嚴(yán)格監(jiān)控最后的純化過程。
【點評】
　　點評：目前的細胞與組織移植的療法面臨諸多挑戰(zhàn)，想要成功轉(zhuǎn)化為臨床實踐還得先能克服這些挑戰(zhàn)，能否成功還很難說。
【原文摘錄】STEM CELLS 2010;28:996-1004
Concise Review: Mind the Gap: Challenges in Characterizing and Quantifying Cell- and Tissue-Based Therapies for Clinical Translation
Erin A. Rayment *¶, David J. Williams
There are many challenges associated with characterizing and quantifying cells for use in cell- and tissue-based therapies. From a regulatory perspective, these advanced treatments must not only be safe and effective but also be made by high-quality manufacturing processes that allow for on-time delivery of viable products. Although sterility assays can be adapted from conventional bioprocessing, cell- and tissue-based therapies require more stringent safety assessments, especially in relation to use of animal products, immune reaction, and potential instability due to extended culture times. Furthermore, cell manufacturers who plan to use human embryonic stem cells in their therapies need to be particularly stringent in their final purification steps, due to the unrestricted growth potential of these cells. This review summarizes the current issues in characterization and quantification for cell- and tissue-based therapies, dividing these challenges into the regulatory themes of safety, potency, and manufacturing quality. It outlines current assays in use, as well as highlights the limits of many of these product release tests. Mode of action is discussed, with particular reference to in vitro surrogate assays that can be used to provide information to correlate with proposed in vivo patient efficacy. Importantly, this review highlights the requirement for basic research to improve current knowledge on the in vivo fate of these treatments; as well as an improved stakeholder negotiation process to identify the measurement requirements that will ensure the manufacture of the best possible cell- and tissue-based therapies within the shortest timeframe for the most patient benefit.

5. 成人口腔黏膜固有層里有一類新干細胞群
【摘要】
　　成人口腔黏膜固有層里有一類具有明顯的原始神經(jīng)嵴樣表型的原始干細胞群，將其移植到有嚴(yán)重免疫缺陷的老鼠身上時形成了含有來自兩種胚層細胞的腫瘤。這是第一例報道由來自良性成人身體組織的干細胞群形成混合外胚層和中胚層細胞的腫瘤。
【點評】
　　點評：干細胞移植形成腫瘤的風(fēng)險難以避免。
【原文摘錄】STEM CELLS 2010;28:984-995
The Lamina Propria of Adult Human Oral Mucosa Harbors a Novel Stem Cell Population
Keren Marynka-Kalmani 1, Sandra Treves 1, Miri Yafee 1, Heled Rachima 2, Yossi Gafni 1, Malkiel A. Cohen 3, Sandu Pitaru 1 *¶
The highly regenerative capacity of the human adult oral mucosa suggests the existence of a robust stem cell (SC) population in its lamina propria (OMLP). The purpose of this study was to characterize the availability, growth, immunophenotype, and potency of this presumable SC population. Cells positive for the embryonic stem cell transcription factors Oct4 and Sox2 and for p75 formed distinct cord-like structure in the OMLP. Regardless of donor age, trillions of cells, termed human oral mucosa stem cells (hOMSC), 95% of which express mesenchymal stromal cell markers, were simply, and reproducibly produced from a biopsy of 3-4 × 2 × 1 mm3. A total of 40-60% of these cells was positive for Oct4, Sox2, and Nanog and 60-80% expressed constitutively neural and neural crest SC markers. hOMSC differentiated in culture into mesodermal (osteoblastic, chondroblastic, and adipocytic), definitive endoderm and ectodermal (neuronal) lineages. Unexpectedly, hOMSC treated with dexamethasone formed tumors consisting of two germ layer-derived tissues when transplanted in severe combined immune deficiency mice. The tumors consisted of tissues produced by neural crest cells during embryogenesis - cartilage, bone, fat, striated muscle, and neural tissue. These results show that the adult OMLP harbors a primitive SC population with a distinct primitive neural-crest like phenotype and identifies the in vivo localization of putative ancestors for this population. This is the first report on ectodermal- and mesodermal-derived mixed tumors formation by a SC population derived from a nonmalignant somatic adult human tissue.

6. 老鼠ips細胞12號染色體印跡基因異常沉默
【摘要】
　　比較相同遺傳來源的老鼠胚胎干細胞和誘導(dǎo)多能干細胞，發(fā)現(xiàn)大多數(shù)誘導(dǎo)多能干細胞的染色體12qF1上Dlk1–Dio3基因簇異常沉默，因此ips老鼠大多無法完成完整發(fā)育過程。值得注意的是，用組蛋白脫乙酰酶抑制劑處理的Dlk1–Dio3基因簇異常沉默的ips細胞該基因簇復(fù)活能支撐ips老鼠完成完整發(fā)育過程。
【 點評】
　　點評：該文再次證實ips細胞自身基因缺陷造成其無法完成完整發(fā)育過程。
【原文摘錄】Nature, Volume:465,Pages:175–181 doi:10.1038/nature09017
Aberrant silencing of imprinted genes on chromosome 12qF1 in mouse induced pluripotent stem cells
Matthias Stadtfeld, Effie Apostolou, Hidenori Akutsu, et al
Induced pluripotent stem cells (iPSCs) have been generated by enforced expression of defined sets of transcription factors in somatic cells. It remains controversial whether iPSCs are molecularly and functionally equivalent to blastocyst-derived embryonic stem (ES) cells. By comparing genetically identical mouse ES cells and iPSCs, we show here that their overall messenger RNA and microRNA expression patterns are indistinguishable with the exception of a few transcripts encoded within the imprinted Dlk1–Dio3 gene cluster on chromosome 12qF1, which were aberrantly silenced in most of the iPSC clones. Consistent with a developmental role of the Dlk1–Dio3 gene cluster, these iPSC clones contributed poorly to chimaeras and failed to support the development of entirely iPSC-derived animals (‘a(chǎn)ll-iPSC mice’). In contrast, iPSC clones with normal expression of the Dlk1–Dio3 cluster contributed to high-grade chimaeras and generated viable all-iPSC mice. Notably, treatment of an iPSC clone that had silenced Dlk1–Dio3 with a histone deacetylase inhibitor reactivated the locus and rescued its ability to support full-term development of all-iPSC mice. Thus, the expression state of a single imprinted gene cluster seems to distinguish most murine iPSCs from ES cells and allows for the prospective identification of iPSC clones that have the full development potential of ES cells.