5月11日,，Plos One在線發(fā)表了中科院上海生命科學研究院生化與細胞所季紅斌研究組、劉新垣研究組與美國哈佛大學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。
肺癌是嚴重危害我國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“個體化”分子靶向治療提供潛在的藥靶和新的策略,；而可時空調(diào)控基因表達的小鼠模型能夠更好地促進肺癌發(fā)病分子機理的研究。目前國際上應(yīng)用最廣泛的肺癌動物模型就是LSL-K-rasG12D小鼠模型,，可以通過鼻腔滴入攜帶Cre表達基因的腺病毒或與肺上皮細胞特異性的Cre轉(zhuǎn)基因小鼠雜交來實現(xiàn)K-ras突變體的激活,，從而導致肺癌的發(fā)生；而該模型唯一的缺點就是K-ras突變體一旦激活,，就無法調(diào)控其表達和活性,。
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)建了一個可時空調(diào)控K-ras突變體表達的小鼠模型LSL-ER-K-rasG12D；該小鼠的ER-KrasG12D的表達可被CRE誘導,，而ER-K-rasG12D蛋白的激活可通過Tamoxifen來調(diào)控,。在小鼠胚胎成纖維細胞中的研究表明，Tamoxifen處理可以誘導ER-K-rasG12D的激活,，促進細胞異常增殖,、惡性轉(zhuǎn)化以及侵襲和浸潤；而Tamoxifen去除后,，小鼠胚胎成纖維細胞增殖,、惡性轉(zhuǎn)化及侵襲能力可基本恢復到正常水平；動物體內(nèi)研究發(fā)現(xiàn),，通過腹腔注射小鼠Tamoxifen可持續(xù)激活K-rasG12D并促進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發(fā)生細胞凋亡。
該工作在很大程度上提高了人們對K-ras突變體在肺癌發(fā)生、發(fā)展及存活中作用的認識,，并為將來深入研究肺癌發(fā)病分子機理提供一個較為理想的研究體系,，對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,、國家自然科學基金委和上海市科委的經(jīng)費支持,。（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.
