巴氏小體的遺傳學(xué)意義范文

時(shí)間:2023-11-28 18:10:44

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巴氏小體的遺傳學(xué)意義

篇1

[關(guān)鍵詞] 卵巢癌;長(zhǎng)鏈非編碼RNAs;研究進(jìn)展;綜述

[中圖分類(lèi)號(hào)] R730 [文獻(xiàn)標(biāo)識(shí)碼] A [文章編號(hào)] 1673-7210(2016)08(a)-0028-04

[Abstract] lncRNAs are defined as non-coding RNA of more than 200 nt in length. It is called “junk gene” as the result of no protein-coding potential. With the development of various experimental techniques and the deepening of associated researches, the identity of the junk was corrected. Long non-coding RNAs are emerging as hotspots in the field of functional genomics research after mRNA, microRNA. Recently, with the deepening of research on the ovarian cancer associated with lncRNAs, its mechanism had been understood more clear in gradually which make it possible to become a new marker of ovarian cancer and therapeutic targets in the future, but it will be further explorated to understand clearly. The researches of lncRNAs in ovarian cancer is reviewed in this article, aimed to provide new molecular targets for the study of ovarian cancer invasion and treatment.

[Key words] Ovarian cancer; Long non-coding RNAs; Research progress; Review

卵巢癌是三大婦科惡性腫瘤之一,其發(fā)病部位深藏于盆腔內(nèi),并且癥狀隱匿,大部分患者在首次確定病情時(shí)已進(jìn)入到了進(jìn)展期,其臨床致死率最高,發(fā)病率呈逐年遞增之勢(shì),但病因至今不明。卵巢癌的種類(lèi)繁多,其中就以上皮性卵巢癌為主。目前,對(duì)于已確診的卵巢癌患者,臨床上多采用手術(shù)后化療的方式,但因?yàn)槟退幀F(xiàn)象后期反饋欠佳,總體5年生存率不超過(guò)35%[1]。盡管積極給予治療,復(fù)發(fā)轉(zhuǎn)移率仍居高不下,遠(yuǎn)期生存率亦不理想。故而,有關(guān)卵巢腫瘤的發(fā)病分子機(jī)制、早期的協(xié)助診斷、確診后治療方案的選定及后期的隨訪監(jiān)測(cè)等相關(guān)的一些問(wèn)題有待被更深入地了解。本綜述歸納了目前為止與卵巢癌相關(guān)的lncRNAs較新研究進(jìn)展。

長(zhǎng)鏈非編碼RNAs(Long non-coding RNAs,lncRNAs)是一類(lèi)長(zhǎng)度大于200 nt,缺少特異完整的開(kāi)放閱讀框(Open reading frame,ORF)且無(wú)蛋白質(zhì)編碼功能的RNA[2]。根據(jù)lncRNA與蛋白編碼基因的位置關(guān)系將lncRNA分為5類(lèi):正義lncRNA、反義lncRNA、雙向lncRNA、基因間lncRNA和基因內(nèi)lncRNA[3]。lncRNA的調(diào)控機(jī)制復(fù)雜多樣,在轉(zhuǎn)錄水平、轉(zhuǎn)錄后調(diào)控、基因組印記、染色質(zhì)的修飾、剪接調(diào)控、細(xì)胞周期調(diào)控、表觀遺傳學(xué)調(diào)控中均能發(fā)揮重要作用[4-8]。依據(jù)lncRNA的分子功能可將其分為引導(dǎo)分子、骨架分子、信號(hào)分子、誘餌分子4類(lèi)[9]。本文就近期的lncrnas與卵巢癌的相關(guān)研究及取得的進(jìn)展做些簡(jiǎn)要介紹。

1 H19的表達(dá)與卵巢癌的相關(guān)性

H19基因全長(zhǎng)2.5 kb,是在胰島素樣生長(zhǎng)因子2(insulin-like growth factor 2,IGF2)沉默的母源等位基因中表達(dá)的印記基因。IGF2的印跡基因的產(chǎn)物H19是卵巢癌領(lǐng)域最早發(fā)現(xiàn)的lncRNA[10]。IGF2印記基因的變化可引發(fā) H19 高表達(dá),變異的IGF2/H19位點(diǎn)在前列腺癌、結(jié)腸腫瘤、卵巢腫瘤等多種腫瘤中均被發(fā)現(xiàn)[11]。Dammann等[12]發(fā)現(xiàn)大部分卵巢癌中差異性甲基化區(qū)域(Differentially-methylated region,DMR)出現(xiàn)顯著低甲基化,CTCF[12](轉(zhuǎn)錄阻抑物CTCF是CTCF基因編碼的轉(zhuǎn)錄因子,廣泛存在于真核生物中,與絕緣子的活性相關(guān))結(jié)合位點(diǎn)表現(xiàn)出高甲基化,推測(cè)在卵巢癌與這些異常變化可能相關(guān)。并有研究發(fā)現(xiàn)二甲雙胍可通過(guò)DNA 甲基化來(lái)下調(diào)H19的表達(dá),從而抑制腫瘤細(xì)胞的遷移浸潤(rùn),作用機(jī)制與影響 H19/let-7軸中l(wèi)et-7(一種抑癌 Micro RNA)介導(dǎo)的促轉(zhuǎn)移效應(yīng)有關(guān)[13]。

2 失活特異轉(zhuǎn)錄物(X inactive specific transcript,XISTX)與卵巢癌的相關(guān)性

X1IST基因位于X失活中心(X inactivation center,XIC),“劑量補(bǔ)償”效應(yīng)使兩性在實(shí)際X染色體數(shù)目上維持相同,由X失活中心調(diào)控。Xic辨別X染色體數(shù)目的信息和Xist基因,兩者共同作用保證有且僅有一條染色體有活性。根據(jù)Lyon猜想,異染色質(zhì)即巴氏小體(Barr's body)為失活的X染色體(Inactivated X,Xi)的存在形式。通過(guò)對(duì)巴氏小體進(jìn)行染色處理后,即可確認(rèn)女性體細(xì)胞中活性X染色體數(shù)目[14]。2007年Benoit等[15]發(fā)現(xiàn)約50%的卵巢癌細(xì)胞株細(xì)胞內(nèi)XIST水平很低,伴巴氏小體缺失。提示XIST丟失致使X染色體無(wú)法失活,而致使卵巢腫瘤發(fā)生。2002年Huang等[16]研究發(fā)現(xiàn),卵巢腫瘤細(xì)胞中的XIST RNA表達(dá)水平可在化療反應(yīng)敏感性方面成為一種評(píng)估參考。此外,其可能還與卵巢癌的復(fù)發(fā)有關(guān)。

3 同源異型框基因反義基因間RNA(HOX transcript antisense intergenic RNA)與卵巢癌的相關(guān)性

HOTAIR位于12q13.13,由HOX位點(diǎn)轉(zhuǎn)錄而來(lái),是首個(gè)被發(fā)現(xiàn)具有反式轉(zhuǎn)錄調(diào)控作用的lncRNA,據(jù)Marsh等[17]研究發(fā)現(xiàn),HOTAIR基因過(guò)表達(dá)可促進(jìn)多種器官腫瘤的轉(zhuǎn)移。推測(cè)可能是通過(guò)上皮細(xì)胞間質(zhì)化和基質(zhì)金屬蛋白酶3(Matrix metallo preteinases,MMP3)、MMP 9的通路來(lái)完成的。崔玲等[18]發(fā)現(xiàn)HOTAIR mRNA在低度分化的卵巢癌組織中表達(dá)明顯高于中、高分化。據(jù)Qiu等[19]研究顯示,在卵巢癌上皮(Ethernet over cable,EOC)組織中,HOTAIR表達(dá)升高,與腫瘤的分期、分型密切相關(guān),并減少了總生存期和無(wú)病生存率,可將HOTAIR作為患者評(píng)估前兩者的影響因素。下調(diào)HOTAIR可使順鉑耐藥的A2780cicR細(xì)胞敏感性增加,通過(guò)調(diào)節(jié)金屬蛋白酶和上皮間質(zhì)轉(zhuǎn)化相關(guān)基因而被介導(dǎo)是其作用方式之一,HOTAIR有希望作為對(duì)抗順鉑耐藥性分子藥物的研發(fā)突破點(diǎn)之一[18]。

4 LncRNA UCA1與卵巢的相關(guān)性

2015年王帆等[20]實(shí)驗(yàn)發(fā)現(xiàn)在卵巢癌細(xì)胞SKOV3中上調(diào)UCA1 RNA的表達(dá),增加細(xì)胞的遷移及侵襲能力,而且增加細(xì)胞表達(dá)MMP2、MMP9蛋白水平。因而認(rèn)為UCA1 RNA在卵巢癌細(xì)胞中發(fā)揮促進(jìn)侵襲及轉(zhuǎn)移的作用可能是通過(guò)上調(diào)MMP2、MMP9表達(dá)。此研究可能為阻斷卵巢癌侵襲及轉(zhuǎn)移提供新的研究路線,為研究卵巢癌侵襲與進(jìn)展提供新的分子靶點(diǎn)。

5 人卵巢癌特殊轉(zhuǎn)錄本2(Human ovarian cancer specific transcript 2,HOST2)與卵巢癌的相關(guān)性

HOST2定位于10q23.1,有研究表明,HOST2和Clorfl86在上皮性卵巢癌異性高表達(dá),兩者與miR-1266的競(jìng)爭(zhēng)性結(jié)合的結(jié)局或在一定程度上導(dǎo)致了上皮性卵巢癌的發(fā)生與進(jìn)展[21-22]。HOST2調(diào)控下的Clorfl96.JAK2.STAT3信號(hào)通路可能是Clorfl86+這一細(xì)胞亞群生長(zhǎng)得以維持的關(guān)鍵。HOST2和Clorfl86均有潛力作為新的靶標(biāo),用于上皮性卵巢癌的靶向干預(yù)治療。

6 LncRNA肺腺癌轉(zhuǎn)移相關(guān)轉(zhuǎn)錄子1(Matastasis associated lung adenocarcinoma transcript1,MALAT1)與卵巢癌的相關(guān)性

LncRNA MALAT1長(zhǎng)約8000 nt,2003年被Ping等[23]初次報(bào)道,在非小細(xì)胞肺癌中表達(dá)上調(diào),并與患者的預(yù)后相關(guān),后又被證明與肝癌、宮頸癌、膀胱癌及膽囊癌等腫瘤的發(fā)生關(guān)系密切[24]。其在卵巢癌中的作用少有研討觸及,據(jù)2014年劉石萍等[25]研究顯示,在體外下調(diào)MALAT1表達(dá)能夠抑制卵巢癌細(xì)胞的增殖和轉(zhuǎn)移,且下調(diào)MALAT1表達(dá)還能夠降低卵巢癌細(xì)胞的體內(nèi)增殖,其研究表明MALAT1對(duì)卵巢癌有促進(jìn)作用,具備成為新的卵巢癌治療靶點(diǎn)的潛力。

7母系表達(dá)印記基因3(materally expressed gene3,MEG3)與卵巢癌的相關(guān)性

MEG3位于14q32.2,在包括卵巢細(xì)胞在內(nèi)的多種正常細(xì)胞中表達(dá),然而在多種腫瘤細(xì)胞中其啟動(dòng)發(fā)生甲基化后導(dǎo)致其本身的表達(dá)下調(diào)或缺失,如腎細(xì)胞癌、垂體腺瘤、肝細(xì)胞癌等[26]。為了檢測(cè)上皮性卵巢癌組織中MEG3啟動(dòng)子CpG島的甲基化狀態(tài),探討MEG3啟動(dòng)子的甲基化狀態(tài)與上皮性卵巢癌臨床病理特征的關(guān)系,趙琴等[27]發(fā)現(xiàn)MEG3在上皮性卵巢癌中發(fā)生甲基化改變,MEG3啟動(dòng)子區(qū)甲基化的發(fā)生率臨床Ⅰ期和Ⅱ期顯著低于Ⅲ期和Ⅳ期,高中分化的低于低分化。得出結(jié)論:上皮性卵巢癌組織中存在著MEG3啟動(dòng)子的甲基化,提示MEG3啟動(dòng)子異常甲基化可能與上皮性卵巢癌的發(fā)生發(fā)展相關(guān),并可能與上皮性卵巢癌臨床分期及分化程度有關(guān)。

8 Pvt1與卵巢癌的相關(guān)性

Tseng等[28]將焦點(diǎn)放在了包含MYC基因,且常在癌癥中表達(dá)的一個(gè)基因組區(qū)域:8q24。研究小組通過(guò)小鼠實(shí)驗(yàn)表明MYC與PVT1的協(xié)動(dòng)關(guān)系。證實(shí)PVT1是MYC蛋白的一個(gè)關(guān)鍵調(diào)控因子,這改變了我們理解MYC擴(kuò)增癌癥的模式。通過(guò)將MYC和PVT1解配對(duì),研究人員猜想他們可以阻止癌癥生長(zhǎng),將MYC限制于癌前水平。這將使得PVT1成為潛在控制重要癌基因的一個(gè)理想藥物靶點(diǎn)。Tseng等[28]表示現(xiàn)在有兩個(gè)主要的方面可供研究:破壞MYC和PVT1之間的關(guān)系是否能夠在所有MYC驅(qū)動(dòng)的癌癥中,甚至是不由這一特異的遺傳位點(diǎn)驅(qū)動(dòng)的癌癥中起同樣的作用?PVT1是如何穩(wěn)定或是提高細(xì)胞中的MYC的?這一關(guān)系將是開(kāi)發(fā)藥物靶向這一機(jī)制的關(guān)鍵。”

其他關(guān)于卵巢癌lncRNAs的研究層層推進(jìn)發(fā)現(xiàn),越來(lái)越多的lncRNAs參與其發(fā)生發(fā)展中,如LSINCT5的過(guò)表達(dá)[29],AB073614的過(guò)表達(dá)[30],F(xiàn)ALEC的過(guò)表達(dá)[31],CDKN2B-AS1[32]的過(guò)表達(dá),HOXA11-AS[33]的表達(dá)下調(diào),ZNF300P1[34]的表達(dá)下調(diào)等,但進(jìn)一步的探索仍有待深入,lncRNAs臨床意義也將更加突顯。

9 小結(jié)

全球癌癥領(lǐng)域頂級(jí)雜志CA Cancer J Clin 2016年1月25日在線發(fā)表了國(guó)家癌癥中心公布的2015年癌癥統(tǒng)計(jì)數(shù)據(jù),顯示中國(guó)2015年卵巢癌預(yù)估總數(shù)5.21萬(wàn)例,死亡數(shù)2.25萬(wàn)例,針對(duì)卵巢癌患者,盡早給予合適治療對(duì)病人的預(yù)后及其家庭的影響重大。lncRNAs的發(fā)現(xiàn)是中心法則的新補(bǔ)充。盡管人們逐漸認(rèn)識(shí)到lncRNAs在人類(lèi)正常生理和病理中的重要作用,但在卵巢癌中,對(duì)其相關(guān)lncRNAs的認(rèn)識(shí)還很局限。人們對(duì)卵巢癌發(fā)生發(fā)展的機(jī)制仍不夠明了,隨著研究技術(shù)的不斷發(fā)展,研究?jī)?nèi)容的不斷深化,我們預(yù)測(cè)lncRNAs在未來(lái)將會(huì)成為卵巢癌的早期診斷、發(fā)生發(fā)展、侵襲以及預(yù)后的重要分子之一。

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