5月11日,，Plos One在線(xiàn)發(fā)表了中科院上海生命科學(xué)研究院生化與細(xì)胞所季紅斌研究組,、劉新垣研究組與美國(guó)哈佛大學(xué)Dr. Kwok-Kin Wong合作的最新研究成果Temporal Dissection of K-rasG12D Mutant In Vitro and In Vivo Using a Regulatable K-rasG12D Mouse Allele，揭示了K-ras突變體在肺癌發(fā)生,、發(fā)展及存活中的重要作用,。
肺癌是嚴(yán)重危害我國(guó)人民生命健康的重大疾病之一，揭示其中關(guān)鍵的致病基因在肺癌發(fā)生發(fā)展及存活中的作用將為臨床上肺癌的“個(gè)體化”分子靶向治療提供潛在的藥靶和新的策略,；而可時(shí)空調(diào)控基因表達(dá)的小鼠模型能夠更好地促進(jìn)肺癌發(fā)病分子機(jī)理的研究,。目前國(guó)際上應(yīng)用最廣泛的肺癌動(dòng)物模型就是LSL-K-rasG12D小鼠模型，可以通過(guò)鼻腔滴入攜帶Cre表達(dá)基因的腺病毒或與肺上皮細(xì)胞特異性的Cre轉(zhuǎn)基因小鼠雜交來(lái)實(shí)現(xiàn)K-ras突變體的激活,，從而導(dǎo)致肺癌的發(fā)生,；而該模型唯一的缺點(diǎn)就是K-ras突變體一旦激活，就無(wú)法調(diào)控其表達(dá)和活性,。
最近,，季紅斌研究組、劉新垣研究組等在LSL-K-rasG12D小鼠模型基礎(chǔ)上,，構(gòu)建了一個(gè)可時(shí)空調(diào)控K-ras突變體表達(dá)的小鼠模型LSL-ER-K-rasG12D,；該小鼠的ER-KrasG12D的表達(dá)可被CRE誘導(dǎo)，而ER-K-rasG12D蛋白的激活可通過(guò)Tamoxifen來(lái)調(diào)控,。在小鼠胚胎成纖維細(xì)胞中的研究表明,，Tamoxifen處理可以誘導(dǎo)ER-K-rasG12D的激活，促進(jìn)細(xì)胞異常增殖、惡性轉(zhuǎn)化以及侵襲和浸潤(rùn),；而Tamoxifen去除后,，小鼠胚胎成纖維細(xì)胞增殖、惡性轉(zhuǎn)化及侵襲能力可基本恢復(fù)到正常水平,；動(dòng)物體內(nèi)研究發(fā)現(xiàn),，通過(guò)腹腔注射小鼠Tamoxifen可持續(xù)激活K-rasG12D并促進(jìn)小鼠肺部腫瘤的早期發(fā)生，而Tamoxifen撤掉后大部分的肺部腫瘤會(huì)發(fā)生細(xì)胞凋亡,。
該工作在很大程度上提高了人們對(duì)K-ras突變體在肺癌發(fā)生,、發(fā)展及存活中作用的認(rèn)識(shí)，并為將來(lái)深入研究肺癌發(fā)病分子機(jī)理提供一個(gè)較為理想的研究體系,，對(duì)新型肺癌小鼠模型的建立和發(fā)展具有重要意義,。
該研究課題獲得科技部、國(guó)家自然科學(xué)基金委和上海市科委的經(jīng)費(fèi)支持,。（生物谷Bioon.com）
doi:10.1371/journal.pone.0037308
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Temporal Dissection of K-rasG12D Mutant In Vitro and In Vivo Using a Regulatable K-rasG12D Mouse Allele
Zuoyun Wang1#*, Yan Feng1#*, Nabeel Bardessy2, Kwok-Kin Wong3*, Xin-Yuan Liu1*, Hongbin Ji
Animal models which allow the temporal regulation of gene activities are valuable for dissecting gene function in tumorigenesis. Here we have constructed a conditional inducible estrogen receptor-K-rasG12D (ER-K-rasG12D) knock-in mice allele that allows us to temporally switch on or off the activity of K-ras oncogenic mutant through tamoxifen administration. In vitro studies using mice embryonic fibroblast (MEF) showed that a dose of tamoxifen at 0.05 μM works optimally for activation of ER-K-rasG12D independent of the gender status. Furthermore, tamoxifen-inducible activation of K-rasG12D promotes cell proliferation, anchor-independent growth, transformation as well as invasion, potentially via activation of downstream MAPK pathway and cell cycle progression. Continuous activation of K-rasG12D in vivo by tamoxifen treatment is sufficient to drive the neoplastic transformation of normal lung epithelial cells in mice. Tamoxifen withdrawal after the tumor formation results in apoptosis and tumor regression in mouse lungs. Taken together, these data have convincingly demonstrated that K-ras mutant is essential for neoplastic transformation and this animal model may provide an ideal platform for further detailed characterization of the role of K-ras oncogenic mutant during different stages of lung tumorigenesis.
