司海燕綜述,胡成進(jìn)審校
microRNA對乳腺癌發(fā)生發(fā)展的作用及在治療中應(yīng)用近況
司海燕綜述,胡成進(jìn)審校
乳腺癌;微小RNA;生物標(biāo)志物;治療
miRNA在乳腺癌發(fā)生發(fā)展中的作用及其在治療中應(yīng)用的研究進(jìn)展作一綜述。
1.1 miR-21與乳腺癌 miR-21是腫瘤診斷和預(yù)后判斷中最具潛力的新型生物標(biāo)志物之一。近期研究證實miR-21可作為一種癌基因[2],對多種腫瘤的臨床診斷具有重要的參考價值。miR-21在乳腺癌細(xì)胞系、組織及血清中表達(dá)上調(diào),且與腫瘤的臨床分期及預(yù)后相關(guān)[3]。Yan等[4]通過對乳腺癌細(xì)胞系的進(jìn)一步研究,證明miR-21可增強腫瘤細(xì)胞增殖,遷移,侵襲及存活能力。敲除miR-21能夠誘導(dǎo)細(xì)胞凋亡和抑制細(xì)胞的增殖力和侵襲力。動物實驗也證實miR-21在動物體內(nèi)起癌基因的作用。研究者通過對miR-21靶基因的研究,發(fā)現(xiàn)miR-21可靶向作用于多種基因,包括TPM1(tropomyosin 1),PDCD4(programmed cell death 4),maspin和 TGF-β1(human transforming growth factor β1)發(fā)揮生物學(xué)作用[5-8]。
1.2 miR-10b與乳腺癌 Ma等[9]研究表明,miR-10b與腫瘤的轉(zhuǎn)移密切相關(guān)。miR-10b的表達(dá)水平與乳腺癌細(xì)胞系的惡性程度及細(xì)胞轉(zhuǎn)移力呈正相關(guān)。通過對乳腺癌患者病理組織標(biāo)本的分析 ,miR-10b的表達(dá)水平與腫瘤臨床分期顯著相關(guān);miR-10b在有腫瘤轉(zhuǎn)移的樣本中表達(dá)水平顯著高于只有原發(fā)灶的腫瘤樣本[10]。在乳腺癌細(xì)胞系中,通過對miR-10b靶基因的研究,發(fā)現(xiàn)miR-10b通過誘導(dǎo)上皮基質(zhì)轉(zhuǎn)化基因EMT(epithelial-to-mesenchymal transition),促進(jìn)轉(zhuǎn)移因子Twist發(fā)揮生物學(xué)功能;miR-10b通過直接抑制轉(zhuǎn)錄調(diào)節(jié)因子HOXD10的翻譯,抑制多種基因表達(dá)[9]。許多研究團(tuán)隊進(jìn)一步證實miR-10b主要通過Twist-miR-10b-HOXD10-RhoC途徑發(fā)揮生物學(xué)功能[11,12]。
1.3 miR-145與乳腺癌 體內(nèi)外的多項實驗研究證實miR-145具有腫瘤抑制基因的功能,抑制腫瘤細(xì)胞的生長、侵襲和轉(zhuǎn)移能力。Kim等[13]研究結(jié)果顯示,在乳腺癌組織中miR-145表達(dá)量顯著低于癌旁正常乳腺組織。miR-145可使乳腺癌細(xì)胞增殖、遷移和侵襲能力下降,其過表達(dá)可抑制乳腺癌的生長和轉(zhuǎn)移。miR-145介導(dǎo)抑制細(xì)胞侵襲的功能可能與腫瘤轉(zhuǎn)移基因MUC1(mucin 1)的表達(dá)沉默相關(guān)。研究者利用帶有MUC1基因3’-非翻譯端的熒光素酶,聯(lián)合蛋白印記和免疫熒光染色技術(shù),證明MUC1是miR-145的直接作用靶點[14]。另有研究證明,miR-145可能通過介導(dǎo)啟動TP53途徑和靶向作用于雌激素受體α發(fā)揮生物學(xué)作用[15]。
1.4 miR-155與乳腺癌 miR-155在多種腫瘤中表達(dá)上調(diào),預(yù)示miR-155是一種潛在的癌基因。Jiang等[16]研究發(fā)現(xiàn)在乳腺癌細(xì)胞系中,抑癌基因 socs1(suppressor of cytokine signaling 1)是miR-155的作用靶點,miR-155的表達(dá)水平與socs1表達(dá)負(fù)相關(guān)。體外實驗研究證明,異位表達(dá)的miR-155顯著提高了乳腺癌細(xì)胞系的增殖能力。體內(nèi)裸鼠實驗證明,miR-155過表達(dá)促進(jìn)腫瘤的生長。利用乳腺癌細(xì)胞系,通過RNA干擾技術(shù)使socs1表達(dá)沉默,可使miR-155發(fā)揮癌基因的功能增強;恢復(fù)socs1的表達(dá)可使miR-155的功能減弱。Kong等[17]研究證明,高表達(dá)的miR-155可誘導(dǎo)腫瘤細(xì)胞生長,并可誘導(dǎo)化療藥物耐藥。敲除miR-155能促進(jìn)腫瘤細(xì)胞的凋亡,并可提高腫瘤細(xì)胞對化療藥物的敏感性。通過對miR-155調(diào)節(jié)細(xì)胞生存能力和對化療藥物敏感性相關(guān)蛋白的靶基因研究,發(fā)現(xiàn)FOXO3a是miR-155的作用靶點。miR-155的過表達(dá)可抑制FOXO3a蛋白;敲除miR-155可使FOXO3a蛋白表達(dá)上調(diào)。導(dǎo)入缺乏3’-非翻譯端的FOXO3a cDNA,可使miR-155介導(dǎo)細(xì)胞生長和化療藥物耐藥的能力消失,提示miR-155可能成為乳腺癌臨床診斷和治療的作用靶點。
1.5 miR-125b與乳腺癌 miR-125b在乳腺癌組織及細(xì)胞系中表達(dá)下調(diào)。Hasan等[18]研究證明,miR-125b能抑制癌蛋白MUC1的表達(dá),發(fā)揮抑癌基因的作用。研究證明,MUC1 3’-非翻譯端包含結(jié)合miR-125b種子序列的結(jié)合位點,MUC1 3’-非翻譯端抑制熒光素酶的表達(dá);miR-125b結(jié)合位點的突變和缺失可使這種效應(yīng)消失。在BT-549乳腺癌細(xì)胞系中,miR-125b反義引物的表達(dá)誘導(dǎo)MUC1蛋白表達(dá)上調(diào)并且促進(jìn)細(xì)胞生長。另外,利用ZR-75-1乳腺癌細(xì)胞系,使外源性miR-125b過表達(dá),可下調(diào)MUC1蛋白。通過siRNA技術(shù)使MUC1沉默,可促進(jìn)ZR-75-1細(xì)胞DNA損傷,誘導(dǎo)細(xì)胞凋亡。類似的研究結(jié)果顯示,在利用順鉑治療時,miR-125b誘導(dǎo)MUC1水平下調(diào),可促使ZR-75-1細(xì)胞系的凋亡能力增強。另有研究發(fā)現(xiàn)miR-125b在乳腺浸潤性導(dǎo)管癌中表達(dá)下調(diào),這種現(xiàn)象可用miR-125b啟動子的超甲基化來解釋[19]。在乳腺癌細(xì)胞系中恢復(fù)miR-125b的表達(dá)可抑制細(xì)胞的增殖;在體內(nèi)可以抑制腫瘤形成。miR-125b通過靶向作用于轉(zhuǎn)錄因子ETS1發(fā)揮抑癌基因的作用。
1.6 其它miRNA與乳腺癌 研究證明,miR-210、miR-340、miR-126和miR-205等均與乳腺癌腫瘤細(xì)胞的增殖,侵襲及預(yù)后相關(guān)[20-23]。
2.1 miRNA與化療藥物 在乳腺癌組織中miR-128的表達(dá)下調(diào)與化療藥物耐藥和患者生存率下降相關(guān)。Zhu等[24]研究證實,miR-128通過靶向作用于Bmi-1基因 (polycomb基因家族成員)和ABCC5(ATP-binding cassette transporters,ATP結(jié)合盒膜轉(zhuǎn)運蛋白成員)調(diào)節(jié)乳腺癌細(xì)胞系對化療藥物的敏感性。異位高表達(dá)miR-128能降低細(xì)胞活性,增加細(xì)胞凋亡和DNA損害,使乳腺癌細(xì)胞系對抗腫瘤抗生素阿霉素敏感性增強。檢測miR-128的表達(dá)對預(yù)測患者化療藥物敏感性和預(yù)后有重要價值,也為聯(lián)合miR-128治療乳腺癌提供了研究基礎(chǔ)。另有研究證明,miR-451調(diào)控MDR1(multidrug resistance 1)基因,過表達(dá)的miR-451能阻止MDR1的表達(dá),提高M(jìn)CF-7細(xì)胞系對阿霉素的敏感性[25]。另外,miR-326也可通過調(diào)控 MRP-1 (multidrug resistance-associated protein 1)使乳腺癌對化療藥物產(chǎn)生耐藥[26]。
2.2 miRNA與激素依賴性藥物 他莫昔芬(tamoxifen,TAM)是最常用的非甾體抗雌激素藥物,是激素依賴性轉(zhuǎn)移性乳
腺癌治療的一線藥物,也是雌激素受體ER陽性的原發(fā)性乳腺癌治療的首選藥物。大約30%的ER陽性乳腺癌患者對他莫昔芬耐藥。miR-221和miR-222通過靶向作用于細(xì)胞循環(huán)抑制劑p27kip1,調(diào)節(jié)細(xì)胞增殖,發(fā)揮其癌基因的功能。另外,高表達(dá)的miR-221和miR-222靶向作用于p27蛋白,促進(jìn)細(xì)胞由靜止到增殖。Tyler等[27]研究表明,miR-221和miR-222的表達(dá)上調(diào)是乳腺癌他莫昔芬耐藥的潛在的標(biāo)志。另有研究證明,miRNA-30c的表達(dá)與人表皮生長因子受體HER和小GTP酶蛋白RAC1信號傳導(dǎo)途徑相關(guān),miR-30c可作為獨立因素預(yù)測他莫昔芬治療晚期乳腺癌的臨床效果[28]。另外,下調(diào)的miR-342與乳腺癌他莫昔芬耐藥相關(guān)[29]。
2.3 miRNA與分子靶向藥物 曲妥株單抗(trastuzumab)是抗HER2的單克隆抗體,是治療HER2過表達(dá)的轉(zhuǎn)移性乳腺癌的常用藥物。研究證明,miR-21在HER2陽性的乳腺癌細(xì)胞系BT474,SKBR3和MDA-MB-453中表達(dá)上調(diào)。將細(xì)胞系長時間的暴露于抗體中,miR-21具有誘導(dǎo)細(xì)胞系獲得曲妥株單抗耐藥的能力。將miR-21敲除,可使耐藥的細(xì)胞系恢復(fù)對曲妥株單抗的敏感性。PTEN是一種抑癌基因,其蛋白產(chǎn)物含有一酪蛋白磷酸酶的功能區(qū)和約175個氨基酸左右的骨架蛋白tenasin、auxilin同源區(qū)域。PTEN可能與酪氨酸激酶競爭共同的底物,在腫瘤的發(fā)生發(fā)展中起重要作用。體內(nèi)實驗研究表明,通過加入miR-21的反義寡核苷酸序列誘導(dǎo)PTEN的表達(dá),可恢復(fù)曲妥株單抗治療乳腺癌的敏感性;注入miR-21模擬體,使PTEN表達(dá)沉默,可使曲妥株單抗耐藥。同時,通過活組織檢查獲得未經(jīng)曲妥株單抗治療和治療后的乳腺癌患者組織標(biāo)本,miR-21的高表達(dá)與機體對曲妥株單抗的耐藥性相關(guān)。因此,對抗miR-21的表達(dá)在HER2陽性的乳腺癌治療中具有重要的應(yīng)用價值[30,31]。
總之,大量的實驗研究證實miRNA具有成為乳腺癌新型腫瘤標(biāo)志物的潛力。通過對乳腺癌中異常表達(dá)的miRNA靶基因的預(yù)測和驗證,及靶向miRNA技術(shù)在乳腺癌基因治療中的研究,進(jìn)一步明確了乳腺癌發(fā)生、發(fā)展的病理生理機制,在腫瘤的臨床診斷和治療中具有十分廣泛的應(yīng)用前景。另外,miRNA在血液和體液中的穩(wěn)定表達(dá),使miRNA可能成為非侵襲性腫瘤生物標(biāo)志物,在腫瘤早期篩查,疾病進(jìn)展及預(yù)后判斷中具有較好的應(yīng)用價值。
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[2011-12-27收稿,2012-01-20修回]
[本文編輯:韓仲琪]
book=750,ebook=26
R737.9
A乳腺癌是嚴(yán)重威脅女性健康的常見惡性腫瘤之一,其發(fā)病機制尚不清楚。miRNA(microRNA)是一類內(nèi)源性、非編碼的單鏈小分子RNA[1],在腫瘤的發(fā)生發(fā)展中起重要作用。研究發(fā)現(xiàn),miRNA在人乳腺癌細(xì)胞系、組織及血清中異常表達(dá),提示miRNA可能成為一種潛在的腫瘤生物標(biāo)志物用于乳腺癌的臨床診斷,疾病進(jìn)展,預(yù)后評估及治療。本文就
121001,遼寧錦州,遼寧醫(yī)學(xué)院(司海燕);250031,山東濟(jì)南,濟(jì)南軍區(qū)總醫(yī)院實驗診斷科(胡成進(jìn))