張秀偉,郝鳳霞,賀佳妮,謝玲玲,付琳,董千澤,李慶昌
(中國(guó)醫(yī)科大學(xué)1.附屬第四醫(yī)院病理科,沈陽(yáng)110032;2.基礎(chǔ)醫(yī)學(xué)院病理教研室,沈陽(yáng)110001)
染色質(zhì)重塑因子1在肺癌中過(guò)表達(dá)并促進(jìn)肺癌增殖能力
張秀偉1,2,郝鳳霞2,賀佳妮2,謝玲玲2,付琳2,董千澤2,李慶昌2
(中國(guó)醫(yī)科大學(xué)1.附屬第四醫(yī)院病理科,沈陽(yáng)110032;2.基礎(chǔ)醫(yī)學(xué)院病理教研室,沈陽(yáng)110001)
目的檢測(cè)染色質(zhì)重塑因子1(Rsf-1)對(duì)肺癌增殖能力的影響,初步探討Rsf-1促進(jìn)肺癌增殖的分子機(jī)制。方法應(yīng)用Western blot方法篩選Rsf-1高表達(dá)人肺癌H1299、H460細(xì)胞系,通過(guò)小干擾RNA(siRNA)方法干擾內(nèi)源性Rsf-1表達(dá),并檢測(cè)干擾效率。應(yīng)用集落形成、流式細(xì)胞術(shù)檢測(cè)Rsf-1干擾前后肺癌細(xì)胞增殖能力的變化。應(yīng)用Western blot檢測(cè)干擾內(nèi)源性Rsf-1表達(dá)前后肺癌細(xì)胞中增殖相關(guān)因子的變化。結(jié)果Western blot結(jié)果顯示:肺癌細(xì)胞中Rsf-1蛋白表達(dá)水平明顯高于正常支氣管上皮HBE細(xì)胞系,其中H1299、H460細(xì)胞中存在非常明顯的Rsf-1高表達(dá)。轉(zhuǎn)染Rsf-1特異的siRNA于高表達(dá)Rsf-1的H1299和H460細(xì)胞后,其克隆形成明顯少于對(duì)照組(H1299細(xì)胞中對(duì)照組和干擾組分別為123±15和83±9;H460細(xì)胞中對(duì)照組和干擾組分別為218±18和112±17)(P<0.05)。流式細(xì)胞術(shù)結(jié)果顯示:干擾內(nèi)源性Rsf-1表達(dá)后,H1299和H460細(xì)胞中G1期細(xì)胞比例增多(H1299細(xì)胞中對(duì)照組和干擾組分別為56%±5%和71%±7%;H460細(xì)胞中對(duì)照組和干擾組分別為53%±4%和70%±6%),S期細(xì)胞比例減少(H1299細(xì)胞中對(duì)照組和干擾組分別為17%±2%和11%±5%;H460細(xì)胞中對(duì)照組和干擾組分別為19%±2%和10%±5%)。細(xì)胞周期相關(guān)蛋白檢測(cè)結(jié)果:干擾內(nèi)源性Rsf-1表達(dá)后,H1299和H460細(xì)胞中cyclinD1和磷酸化細(xì)胞外調(diào)節(jié)蛋白激酶(pERK)水平明顯下調(diào)。干擾Rsf-1在下調(diào)H1299和H460細(xì)胞pERK蛋白表達(dá)的作用結(jié)果與應(yīng)用細(xì)胞外調(diào)節(jié)蛋白激酶(ERK)抑制劑U0126相似。結(jié)論Rsf-1可通過(guò)cyclinD1/ERK相關(guān)通路促進(jìn)肺癌細(xì)胞的增殖。
染色質(zhì)重塑因子1;肺癌;小干擾RNA;磷酸化細(xì)胞外調(diào)節(jié)蛋白激酶;cyclinD1
在染色體11q13.5區(qū)域的眾多基因中,染色質(zhì)重塑因子1(remodeling and spacing factor-1,Rsf-1)越來(lái)越受到關(guān)注。研究顯示,Rsf-1在卵巢癌、乳腺癌等多種惡性腫瘤中存在過(guò)表達(dá)和(或)基因擴(kuò)增,且與腫瘤細(xì)胞的惡性程度、增殖能力及患者預(yù)后等顯著相關(guān)。我們之前的研究表明,Rsf-1在肺癌中也存在蛋白過(guò)表達(dá)和mRNA水平上調(diào)。雖然有文獻(xiàn)報(bào)道Rsf-1蛋白與hSNF2H形成復(fù)合體后可引起細(xì)胞增殖,但引起哪些與增殖有關(guān)的因子改變和機(jī)制尚不清楚。本研究應(yīng)用Western blot方法篩選出Rsf-1高表達(dá)的肺癌細(xì)胞系,采用小干擾RNA(small interfering RNA,siRNA)等方法,分析Rsf-1對(duì)肺癌細(xì)胞增殖的影響,探討其可能的分子機(jī)制。
1.1 細(xì)胞培養(yǎng)與siRNA干擾
人肺癌H1299、A549、SPC、H157、LK2、H460細(xì)胞系及正常人支氣管上皮細(xì)胞HBE細(xì)胞系均購(gòu)自上海中科院細(xì)胞庫(kù),用含10%熱滅活新鮮小牛血清的DMEM(美國(guó)Gibco公司)、100 U/mL青霉素、100 U/mL鏈霉素的培養(yǎng)基,在37℃、5%CO2的條件下培養(yǎng)。Rsf-1特異性干擾序列為GGAAAGACAUCUCU ACUAUUU(L-020374-01-0005),陰性對(duì)照組亂序?qū)φ誷iRNA序列為GAAGCAACGUAUCUUGA#1(D-001810-01-05),干擾Rsf-1siRNA以及亂序?qū)φ誷iRNA購(gòu)自美國(guó)Dharmacon公司,采用DharmaFECT 1(美國(guó)Thermo Fisher Scientific公司)依說(shuō)明書進(jìn)行瞬時(shí)轉(zhuǎn)染,并驗(yàn)證干擾效果。
1.2 Western blot檢測(cè)蛋白表達(dá)
收集細(xì)胞加入裂解液充分裂解,低溫高速離心(4℃,12 000 r/min,30 min),提取上清為總蛋白。上樣蛋白量為60 μg。電泳(12%SDS-PAGE凝膠)、5%正常小牛血清封閉,抗Rsf-1(1∶1 000,美國(guó)Upstate公司)、cyclinD1、cyclinE、CDK4/6、細(xì)胞外調(diào)節(jié)蛋白激酶(extracellular-regulated protein kinase,ERK)、磷酸化細(xì)胞外調(diào)節(jié)蛋白激酶(phosphorylation of extracellular-regulated protein kinase,pERK)(1∶1 000,美國(guó)Cell Signaling公司)和抗β-actin(1∶500,北京中杉),4℃孵育過(guò)夜,分別與各自對(duì)應(yīng)的二抗(1∶2 500,美國(guó)Santa Cruz公司)室溫孵育2 h,ECL(美國(guó)Millopore公司)顯色,結(jié)果經(jīng)自動(dòng)電泳凝膠成像分析儀(Chemi Imager 5500,美國(guó)Alpha Innotech公司)采集。
1.3 實(shí)時(shí)PCR(SYBR Green法)
收集轉(zhuǎn)染干擾Rsf-1及對(duì)照siRNA的H1299和H460細(xì)胞,使用Trizol提取RNA,用實(shí)時(shí)PCR驗(yàn)證干擾效率,Rsf-1引物序列:正義:5′-GATACTATGCG TCTCCAGCCAA-3′,反義:5′-CAACTCGTTTCGATT TCTGACAA-3′。Rsf-1mRNA表達(dá)水平的相對(duì)定量分析采用SYBR Premix Ex TaqTMⅡ試劑盒,以β-actin基因?yàn)閮?nèi)參,在ABI 7900型實(shí)時(shí)定量PCR儀上進(jìn)行檢測(cè)。β-actin正義:5′-ATAGCACAGCCTGGATAGC AACGTAC-3′,反義:5′-CACCTTCTACAATGAGCTG CGTGTG-3′。
1.4 集落形成試驗(yàn)
轉(zhuǎn)染干擾Rsf-1及對(duì)照siRNA后24 h,將細(xì)胞經(jīng)0.25%胰蛋白酶消化制成單細(xì)胞懸液,進(jìn)行細(xì)胞計(jì)數(shù),將500個(gè)細(xì)胞種植于直徑3 cm培養(yǎng)皿中,繼續(xù)培養(yǎng)1周后終止培養(yǎng),甲醇固定,Giemsa染色,鏡下計(jì)數(shù)超過(guò)50個(gè)細(xì)胞的集落。
1.5 細(xì)胞周期檢測(cè)
將大約50%密度的H1299和H460細(xì)胞鋪到6孔板中,轉(zhuǎn)染干擾Rsf-1及對(duì)照siRNA,先饑餓24 h,達(dá)到同步化后再換含10%胎牛血清培養(yǎng)24 h后收集細(xì)胞,離心,PBS清洗,加入75%乙醇4℃固定4 h,離心,PBS清洗,加入碘化丙錠,室溫避光30 min后上機(jī)檢測(cè)細(xì)胞周期。
1.6 統(tǒng)計(jì)學(xué)分析
采用SPSS 10.0統(tǒng)計(jì)分析軟件,組間數(shù)據(jù)比較采用t檢驗(yàn),P<0.05為差異有統(tǒng)計(jì)學(xué)意義。
2.1 Rsf-1在肺癌細(xì)胞中過(guò)表達(dá)
采用Western blot篩選人肺癌H1299、A549、SPC、H157、LK2、H460細(xì)胞系及正常人支氣管上皮細(xì)胞HBE細(xì)胞系后發(fā)現(xiàn),H1299、H460和SPC這3種肺癌細(xì)胞中Rsf-1的蛋白表達(dá)水平明顯高于正常的HBE細(xì)胞系,其中在H1299和H460細(xì)胞中存在非常明顯的Rsf-1高表達(dá)(圖1A)。采用實(shí)時(shí)PCR驗(yàn)證干擾效率,結(jié)果轉(zhuǎn)染干擾Rsf-1特異siRNA的H1299和H460細(xì)胞其Rsf-1mRNA含量比對(duì)照組細(xì)胞明顯下降(P<0.05)(圖1B)。
2.2 干擾Rsf-1表達(dá)下調(diào)肺癌細(xì)胞的增殖能力
轉(zhuǎn)染干擾Rsf-1及對(duì)照siRNA于H1299和H460細(xì)胞,將轉(zhuǎn)染48 h后的細(xì)胞進(jìn)行集落接種,1周后計(jì)數(shù)克隆形成情況,干擾Rsf-1組的H1299和H460細(xì)胞的集落形成明顯少于對(duì)照組(圖2)。H1299細(xì)胞中對(duì)照組和干擾組分別為123±15和83±9,H460細(xì)胞中對(duì)照組和干擾組分別為218±18和112±17,均有統(tǒng)計(jì)學(xué)差異(P<0.05)。
2.3Rsf-1通過(guò)cyclinD1/ERK影響肺癌細(xì)胞增殖
干擾Rsf-1的表達(dá)后,G1期細(xì)胞的比例增多,H1299細(xì)胞中對(duì)照組和干擾組分別為56%±5%和71%±7%,H460細(xì)胞中對(duì)照組和干擾組分別為53%±4%和70%±6%;S期細(xì)胞比例減少,H1299細(xì)胞中對(duì)照組和干擾組分別為17%±2%和11%±5%,H460細(xì)胞中對(duì)照組和干擾組分別為19%±2%和10%±5%(圖3),提示Rsf-1可能通過(guò)細(xì)胞周期調(diào)控來(lái)影響肺癌細(xì)胞的增殖能力。我們檢測(cè)了一系列與細(xì)胞周期相關(guān)的蛋白表達(dá)情況,發(fā)現(xiàn)干擾Rsf-1后,細(xì)胞cyclinD1的水平明顯下調(diào),同時(shí)pERK水平明顯下調(diào)(圖4)。Western blot結(jié)果顯示,干擾Rsf-1下調(diào)pERK的蛋白表達(dá)水平與應(yīng)用抑制劑U0126的結(jié)果相似,均明顯低于對(duì)照組(圖5),這個(gè)結(jié)果提示Rsf-1可能通過(guò)ERK相關(guān)通路影響肺癌細(xì)胞的增殖能力。
圖1 Rsf-1在肺癌細(xì)胞系中的表達(dá)及其干擾效率Fig.1 Rsf-1 expression in lung cancer cell lines
圖2 干擾Rsf-1明顯抑制肺癌細(xì)胞增殖能力Fig.2 Colony formation assay result showed that Rsf-1 knockdown inhibited cell proliferation
圖3 干擾Rsf-l抑制肺癌細(xì)胞G1~S期進(jìn)展Fig.3 Depletion of Rsf-1 inhibited cell cycle progression
圖4 干擾Rsf-1下調(diào)cyclinD1和pERK水平Fig.4 Rsf-1 knockdown decreased cyclinD1 expression and ERK in both cell lines
圖5 干擾Rsf-1與應(yīng)用ERK抑制劑U0126一樣下調(diào)肺癌細(xì)胞pERK水平Fig.5 Rsf-1 knockdown had the same effect with U0126 in the aspect of decrease the levels of pERK in both cell lines
Rsf-1位于11q13.5,是在Hela細(xì)胞核中發(fā)現(xiàn)的新基因[1]。染色體區(qū)域11q13是在人體腫瘤中最常見(jiàn)的擴(kuò)增區(qū)域之一[2~8],該區(qū)域的某些基因擴(kuò)增存在于卵巢癌、乳腺癌、食管癌、口腔鱗癌等上皮性惡性腫瘤中,這些基因包括Rsf-1、EMSY、PAK1、TAOS1、Rad9、CCND1、FGF3與FGF4等。研究顯示,存在于11q13.5區(qū)域的Rsf-1基因在卵巢癌與乳腺癌等多種惡性腫瘤中存在明顯擴(kuò)增,并且具有促進(jìn)腫瘤細(xì)胞增殖的能力[2,9,10]。有研究表明Rsf-1促進(jìn)腫瘤細(xì)胞增殖的作用依賴于其能夠與hSNF2H蛋白形成RSF復(fù)合體[11]。Shih等[8,11]報(bào)道Rsf-1參與調(diào)控核因子κB(nuclear factor κB,NF-κB)和ERK信號(hào)通路的幾個(gè)相關(guān)基因表達(dá)的改變,從而與腫瘤細(xì)胞惡性生物學(xué)行為相關(guān)。結(jié)腸癌研究中Rsf-1可通過(guò)調(diào)控cyclinE和pRb促進(jìn)腫瘤生長(zhǎng)[12]。新近的研究顯示,Rsf-1可以通過(guò)與cyclinE結(jié)合從而促進(jìn)卵巢癌細(xì)胞增殖[13]。但到目前為止Rsf-1在肺癌中對(duì)腫瘤惡性生物學(xué)行為的影響及機(jī)制尚待闡明。
我們之前的研究表明,Rsf-1在肺癌中也存在過(guò)表達(dá),提示其與肺癌惡性程度存在一定關(guān)系。為了研究Rsf-1在肺癌中對(duì)腫瘤增殖能力的影響及作用機(jī)制,我們通過(guò)Western blot方法篩選出Rsf-1高表達(dá)的肺癌細(xì)胞系H1299、H460。應(yīng)用Rsf-1特異siRNA瞬時(shí)轉(zhuǎn)染干擾內(nèi)源性Rsf-1表達(dá)后,發(fā)現(xiàn)肺癌細(xì)胞克隆形成率明顯減少。同時(shí)應(yīng)用流式細(xì)胞術(shù)檢測(cè)干擾Rsf-1基因后細(xì)胞周期的改變,發(fā)現(xiàn)H1299和H460細(xì)胞中G1期細(xì)胞增多、S期細(xì)胞減少,細(xì)胞G1~S期過(guò)渡受到明顯抑制,提示Rsf-1可能調(diào)控了與肺癌細(xì)胞生長(zhǎng)和增殖相關(guān)的某些基因的改變。眾所周知,cyclinD1是G1~S期過(guò)渡的關(guān)鍵調(diào)節(jié)因子,它能與CDK4/6形成復(fù)合體,在許多腫瘤中呈現(xiàn)出過(guò)表達(dá)共同調(diào)控細(xì)胞周期[14]。研究表明,活化的ERK通過(guò)激活轉(zhuǎn)錄因子,增強(qiáng)cyclinD1基因的表達(dá),從而促進(jìn)細(xì)胞惡性增殖,ERK為cyclinD1表達(dá)的上游分子。cyclinD1的轉(zhuǎn)錄是依賴于ERK信號(hào)傳導(dǎo)通路的持續(xù)激活和滯留于細(xì)胞核內(nèi)完成的[15]。為了驗(yàn)證Rsf-1促進(jìn)肺癌細(xì)胞增殖的作用是否也依賴cyclinD1/ERK相關(guān)通路,我們檢測(cè)了一系列與細(xì)胞周期相關(guān)的蛋白表達(dá)情況。Western blot結(jié)果發(fā)現(xiàn),在H1299、H460細(xì)胞中干擾Rsf-1組與對(duì)照組相比cyclinD1蛋白表達(dá)水平均下調(diào);CDK4/6在H1299細(xì)胞中沒(méi)有明顯變化,只有CDK4在H460細(xì)胞中出現(xiàn)下調(diào)。表明Rsf-1基因具有調(diào)控細(xì)胞周期相關(guān)蛋白表達(dá)的功能,并且主要影響的是G1期進(jìn)程。有報(bào)道Rsf-1參與調(diào)控NF-κB和ERK信號(hào)通路中幾個(gè)相關(guān)基因的表達(dá),同時(shí)RAF-MEK-ERK通路在惡性腫瘤中起著至關(guān)重要的作用[16]。因此我們也檢測(cè)了ERK和pERK,發(fā)現(xiàn)干擾Rsf-1基因表達(dá)后在兩種細(xì)胞中pERK蛋白表達(dá)水平均出現(xiàn)一定程度的下調(diào)。在此基礎(chǔ)上我們發(fā)現(xiàn),干擾Rsf-1在下調(diào)pERK蛋白表達(dá)中的作用與應(yīng)用ERK抑制劑U0126相似。上述結(jié)果說(shuō)明Rsf-1具有調(diào)控細(xì)胞周期相關(guān)蛋白表達(dá)的功能,并且主要影響的是G1期進(jìn)程。同時(shí)也表明Rsf-1不僅通過(guò)細(xì)胞周期,還可通過(guò)ERK等多種其他途徑發(fā)揮調(diào)控細(xì)胞增殖的作用。
綜上所述,我們的研究發(fā)現(xiàn)Rsf-1能夠促進(jìn)肺癌增殖;Rsf-l通過(guò)cyclinD1/ERK相關(guān)通路調(diào)節(jié)肺癌細(xì)胞的增殖能力。這些結(jié)果豐富了Rsf-1促進(jìn)腫瘤的可能機(jī)制,使其可能成為治療肺癌的新靶點(diǎn)。
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(編輯 陳姜)
Remodeling and Spacing Factor1 is Overexpressed and Promotesthe Tumor CellProliferation in Lung Cancer
ZHANGXiu-wei1,2,HAO Feng-xia2,HEJia-ni2,XIELing-ling2,F(xiàn)ULin2,DONG Qian-ze2,LIQing-chang2
(1.DepartmentofPathology,The Fourth Affiliated Hospital,China MedicalUniversity,Shenyang 110032,China;2.DepartmentofPathology,College ofBasic Medical Science,China MedicalUniversity,Shenyang 110001,China)
ObjectiveTo study the relationship between remodeling and spacing factor 1(Rsf-1)expression and tumor cell proliferation in lung cancers.MethodsSmall interfering RNA(siRNA)was used to knockdown the high endogenousRsf-1expression in H1299 and H460 cell lines. Colony formation assays and flow cytometry were employed to detect the change of cell proliferation ability of H1299 and H460 cells.The expression of proliferation related factor changes after interference was evaluate by Western blot.ResultsKnockdown of Rsf-1 expression in H1299 and H460 cells resulted in a decrease of clone formation ability(H1299 control vs siRNA:123±15 vs 83±9;H460 control vs siRNA:218±18 vs 112±17,P<0.05).Rsf-1knockdown induced cell cycle arrest at the G1/S boundary to inhibit cell proliferation,G1phase cells(H1299 control vs siRNA:56%± 5%vs 71%±7%;H460 control vs siRNA:53%±4%vs 70%±6%),S phase cells(H1299 control vs siRNA:17%±2%vs 11%±5%;H460 control vs siRNA:19%±2%vs 10%±5%)(P<0.05).Western blot results revealed that knockdown ofRsf-1decreased cyclinD1 and phosphorylation of extracellular-regulated protein kinase(pERK)protein level in both cell lines.At the same time,Rsf-1knockdown showed the same effect with U0126 in down-regulating the levelsofpERKin both celllines.ConclusionRsf-1 contributes to malignantcellgrowth by modulatingcyclinD1expression andERKactivity,which makesRsf-1a potentialtherapeutic targetin lung cancer.
remodeling and spacing factor 1;lung cancer;small interfering RNA;phosphorylation of extracellular-regulated protein kinase;cyclinD1
R734.2
A
0258-4646(2014)09-0821-05
高等學(xué)校博士學(xué)科點(diǎn)專項(xiàng)科研基金(20132104110025)
張秀偉(1973-),女,主治醫(yī)師,博士研究生.
李慶昌,E-mail:liqingch@hotmail.com
2014-06-17
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