趙艷,李麗華,趙頌
青蒿琥酯抑制人頭頸部鱗狀細(xì)胞癌增殖及誘導(dǎo)凋亡的機(jī)制
趙艷,李麗華△,趙頌
目的探討天然小分子化合物青蒿琥酯(Akt)通過誘導(dǎo)人頭頸部鱗癌細(xì)胞凋亡而抑制腫瘤生長的分子機(jī)制。方法培養(yǎng)人頭頸部鱗癌細(xì)胞系UM-SCC-10A,利用四甲基偶氮唑藍(lán)(MTT)法檢測(cè)Akt半數(shù)抑制濃度(IC50);在熒光顯微鏡下觀察不同濃度(0、2.5、5、10、20、40 μmol/L)Akt對(duì)細(xì)胞形態(tài)的影響;流式細(xì)胞儀檢測(cè)細(xì)胞周期及凋亡情況;免疫印跡(Western blot)分析Akt誘導(dǎo)凋亡相關(guān)蛋白和細(xì)胞周期調(diào)節(jié)因子表達(dá)水平的變化。結(jié)果Akt對(duì)UMSCC-10A細(xì)胞的生長有明顯抑制作用,且生長抑制率隨藥物濃度增加而增加;當(dāng)Akt處理細(xì)胞48 h時(shí),IC50為15.01 μmol/L。熒光顯微鏡下,使用細(xì)胞核染料Hoechst33258觀察到細(xì)胞核內(nèi)出現(xiàn)凋亡小體;流式細(xì)胞儀分析顯示Akt誘導(dǎo)細(xì)胞周期阻滯在G1期,細(xì)胞出現(xiàn)大量凋亡;Western blot結(jié)果顯示P53、P21蛋白表達(dá)量上調(diào)、細(xì)胞周期蛋白D(Cy?cline D)下調(diào);線粒體途徑誘導(dǎo)的Bcl-2相關(guān)X蛋白(Bax)、細(xì)胞色素C(cytochrome C)及半胱氨酸天冬氨酸蛋白酶-3(caspase-3)表達(dá)上調(diào),B細(xì)胞淋巴瘤/白血病-2(Bcl-2)、procaspase-3表達(dá)下調(diào),線粒體膜電位降低。結(jié)論Akt經(jīng)由線粒體途徑誘導(dǎo)UM-SCC-10A細(xì)胞凋亡,阻滯細(xì)胞周期于G1期,進(jìn)而抑制腫瘤細(xì)胞增殖。
細(xì)胞凋亡;細(xì)胞增殖;頭頸部腫瘤;青蒿琥酯
頭頸部鱗狀細(xì)胞癌(HNSCC)是原發(fā)于口腔頜面頭頸部的惡性腫瘤,其發(fā)病率約占頭頸部腫瘤的80%以上。近年來,臨床上對(duì)于HNSCC雖然采用了手術(shù)、放化療等綜合性的治療措施,但其5年生存率仍然徘徊在50%左右[1]。青蒿琥酯(Artesunate,Art)為倍半萜內(nèi)酯類抗瘧新藥青蒿素的衍生物,不僅存在抗瘧、抗菌等活性,還可以抗多種腫瘤細(xì)胞增殖[2],具有毒性低、不存在交叉耐藥、可以逆轉(zhuǎn)腫瘤細(xì)胞的多耐藥性等優(yōu)勢(shì)。對(duì)于一些急性白血病[3]、婦科腫瘤[4]以及胰腺癌[5]的治療已進(jìn)入臨床試驗(yàn)階段,但對(duì)于頭頸部鱗癌的作用還鮮見報(bào)道。本研究以UM-SCC-10A細(xì)胞系為模型,探討Art誘導(dǎo)細(xì)胞凋亡、抑制細(xì)胞生長的機(jī)制,為臨床應(yīng)用提供理論依據(jù)。
1.1 材料
1.1.1 試劑UM-SCC-10A細(xì)胞系購于上海細(xì)胞生物研究所。Art(蘇州寶澤堂醫(yī)藥科技有限公司,純度99%);胎牛血清、青霉素、鏈霉素、L-谷氨酰胺及四甲基偶氮唑藍(lán)(MTT)均購于Sigma公司;caspase抑制劑Z-VAD-FMK、二甲基亞楓(DMSO)、Annexin V-FITC、DNA檢測(cè)試劑盒(美國BD公司);單克隆抗體P21、P53、細(xì)胞周期蛋白D(Cycline D)、B細(xì)胞淋巴瘤/白血病-2(Bcl-2)、Bcl-2相關(guān)X蛋白(Bax)、細(xì)胞色素C(cytochrome C)及半胱氨酸天冬氨酸蛋白酶-3(cas?pase-3,美國Cell signaling公司)。Hoechst33258、多聚甲醛、JC-1試劑盒購于碧云天。
1.1.2 儀器流式細(xì)胞儀FACS Calibur(美國BD公司);細(xì)胞培養(yǎng)箱(Thermo Scientific HERAcell 240i);全自動(dòng)酶標(biāo)儀(BioTek Synergyz)。
1.2 方法
1.2.1 細(xì)胞培養(yǎng)細(xì)胞置于含10%熱滅活胎牛血清、2 mmol/L L-谷氨酰胺、100 U/mL青霉素和100 g/mL鏈霉素的DMEM培養(yǎng)基中,放于37℃、5%CO2細(xì)胞培養(yǎng)箱中培養(yǎng)。每2~4 d傳代1次,取對(duì)數(shù)生長期細(xì)胞進(jìn)行實(shí)驗(yàn)。
1.2.2 半數(shù)抑制濃度(IC50)分析取對(duì)數(shù)生長期細(xì)胞,以5× 103/孔密度接種于96孔培養(yǎng)板,37℃培養(yǎng)24 h,加入含終濃度分別為0、2.5、5、10、20、40 μmol/L Akt培養(yǎng)液,每個(gè)濃度設(shè)5個(gè)復(fù)孔,繼續(xù)培養(yǎng)48 h,然后再加入10 μL MTT溶液(5 g/ L),37℃培養(yǎng)4 h后,2 000 r/min離心10 min,小心吸去上清液,每孔加入150 μL DMSO,于振蕩器上振蕩15 min,在全自動(dòng)酶標(biāo)儀570 nm處測(cè)定光密度(OD)值,計(jì)算細(xì)胞生長抑制率。SPSS-PROBIT法計(jì)算IC50。
1.2.3 實(shí)驗(yàn)分組分別取IC50附近2個(gè)劑量濃度10 μmol/L和20 μmol/L的Akt處理48 h組,和用PBS代替Akt的對(duì)照組進(jìn)行實(shí)驗(yàn)檢測(cè)。在細(xì)胞周期和細(xì)胞凋亡的檢測(cè)中加入caspase抑制劑組來探討凋亡路徑,caspase抑制劑組細(xì)胞預(yù)先用50 μmol/L Z-VAD-FMK處理2 h,然后與20 μmol/L Akt組一起培養(yǎng)。
1.2.4 細(xì)胞核染色用4%多聚甲醛室溫固定細(xì)胞15 min,PBS洗1次,然后用Hoechst33258(50 mg/L)染色,37℃避光孵育20 min,PBS洗3次,在熒光顯微鏡下觀察細(xì)胞核形態(tài)。
1.2.5 細(xì)胞凋亡檢測(cè)用Annexin V和PI雙染試劑盒檢測(cè)細(xì)胞凋亡情況。收集細(xì)胞,用PBS洗2次,棄去上清,加入5 μL Annexin V(10 mg/L)避光孵育10 min,再加入10 μL PI(20 mg/L),避光孵育10 min,流式細(xì)胞儀檢測(cè)細(xì)胞凋亡率,采用cell-quest軟件對(duì)數(shù)據(jù)進(jìn)行獲取和分析。
1.2.6 細(xì)胞周期檢測(cè)收集細(xì)胞,用含2%胎牛血清的PBS洗1次,用75%預(yù)冷乙醇固定2 h,PBS洗2次,計(jì)數(shù)細(xì)胞1× 106個(gè)/mL,加入1 mL PI染液(3.8 mmol/L檸檬酸鈉、20 mg/L PI、10 mg/L RNase A),室溫避光孵育15 min,用流式細(xì)胞儀檢測(cè)細(xì)胞各個(gè)周期的DNA含量,采用cell-quest軟件對(duì)數(shù)據(jù)進(jìn)行獲取和分析。
1.2.7 線粒體膜電位檢測(cè)收集細(xì)胞,用PBS洗2次,加入0.5 mL JC-1染液,37℃避光孵育20 min,PBS洗2次,重懸于500 μL PBS中,用流式細(xì)胞儀檢測(cè)。
1.2.8 免疫印跡(Western blot)分析收集細(xì)胞,用PBS洗2次,加入細(xì)胞裂解液裂解并提取蛋白樣本,煮沸變性5 min,上樣于10%SDS-PAGE電泳分離,電轉(zhuǎn)移至PVDF膜上,用5%(w/v)脫脂乳室溫封閉1 h,然后用Tris-HCl洗1次,立即加入一抗溶液,平緩搖動(dòng),4℃過夜,室溫下加二抗孵育1 h。以β-actin作為內(nèi)參照,顯影參照ECL試劑盒說明書操作。分析P53、P21、Cycline D、Bcl-2、Bax、cytochrome C、procas?pase-3、caspase-3蛋白表達(dá)。
1.3 統(tǒng)計(jì)學(xué)方法采用SPSS 13.0軟件對(duì)數(shù)據(jù)進(jìn)行分析。計(jì)量資料以表示,多組間比較采用單因素方差分析,組間多重比較采用LSD-t檢驗(yàn)。P<0.05為差異有統(tǒng)計(jì)學(xué)意義。
2.1 Akt對(duì)UM-SCC-10A細(xì)胞增殖的影響結(jié)果顯示Akt能明顯抑制細(xì)胞增殖,0、2.5、5、10、20、40 μmol/L時(shí),細(xì)胞增殖抑制率分別為0、(20.17±0.90)%、(30.70±1.18)%、(52.21±0.67)%、(57.22±1.01)%、(60.23±0.70)%,生長抑制作用隨藥物濃度增加而增強(qiáng)。細(xì)胞經(jīng)Akt處理48 h后,IC50值為15.01 μmol/L。
2.2 細(xì)胞核形態(tài)觀察對(duì)照組可見細(xì)胞核染色均勻,呈圓形或橢圓形。10 μmol/L Akt組可見細(xì)胞核變形、核固縮,可見凋亡小體(箭頭所示),20 μmol/L Akt組可見細(xì)胞幾乎沒有完整的核,可見核變形,如典型的月牙形細(xì)胞核(箭頭所示),見圖1。
2.3 Akt對(duì)UM-SCC-10A細(xì)胞凋亡的影響10、20 μmol/L Akt組與對(duì)照組相比凋亡率均增加,20 μmol/L Akt組比10 μmol/L Akt組增加更明顯,而caspase抑制劑組與對(duì)照組比較沒有明顯增加,見圖2。
2.4 Akt對(duì)UM-SCC-10A細(xì)胞周期的影響10、20 μmol/L Akt組、caspase抑制劑組與對(duì)照組相比,G1期DNA含量增加,S和G2期均減少,20 μmol/L Akt組、caspase抑制劑組比10 μmol/L Akt組效果更明顯,caspase抑制劑組與20 μmol/L Akt組無明顯差異,見圖3。
2.5 Akt對(duì)線粒體膜電位的影響10、20 μmol/L Akt組與對(duì)照組相比,線粒體膜電位均降低,20 μmol/L Akt組比10 μmol/L Akt組降低更明顯,見圖4。
2.6 細(xì)胞周期調(diào)節(jié)因子的表達(dá)對(duì)照組、10 μmol/L Akt組、20 μmol/L Akt組相比,Cyclin D表達(dá)量依次降低,P21表達(dá)量依次增加;20 μmol/L Akt組P53表達(dá)量高于對(duì)照組和10 μmol/L Akt組,而后兩組P53表達(dá)量差異無統(tǒng)計(jì)學(xué)意義,見圖5、表1。
2.7 Bcl-2、Bax、procaspase-3、caspase-3、cyto?chrome C蛋白量的表達(dá)對(duì)照組、10 μmol/L Akt組、20 μmol/L Akt組相比,Bcl-2、procaspase-3表達(dá)量依次減少,cytochrome C、Bax和caspase-3表達(dá)量依次增加(均P<0.05),見圖6、表2。
Fig.5 Expressions of cell cycle regulator after 48-hour treatment with different concentrations of Akt圖5 不同濃度Akt作用48 h后UM-SCC-10A細(xì)胞周期調(diào)節(jié)因子的表達(dá)
Tab.1Expressions of cell cycle regulator after 48-hour treatment with different concentrations of Akt表1 不同濃度Akt作用48 h后UM-SCC-10A細(xì)胞周期調(diào)節(jié)因子的表達(dá)(n=5,)
Tab.1Expressions of cell cycle regulator after 48-hour treatment with different concentrations of Akt表1 不同濃度Akt作用48 h后UM-SCC-10A細(xì)胞周期調(diào)節(jié)因子的表達(dá)(n=5,)
*P<0.05,**P<0.01;a與(1)組比較,b與(2)組比較,P<0.05;表2同
組別對(duì)照組(1)10 μmol/L Art組(2)20 μmol/L Art組(3)F Cyclin D 1.98±0.24 1.14±0.29a0.18±0.05ab50.071**P21 0.84±0.11 1.02±0.27a1.41±0.12ab7.519*P53 0.95±0.09 1.01±0.07 1.46±0.34ab5.469*
Fig.6 The apoptotic associated protein expression after 48-hour treatment with different concentrations of Akt圖6 不同濃度Akt作用48 h后UM-SCC-10A細(xì)胞凋亡相關(guān)蛋白的表達(dá)情況
3.1 青蒿琥酯抑制UM-SCC-10A細(xì)胞增殖Akt作為天然化合物,具有高效、低毒、不易產(chǎn)生耐受等特點(diǎn),已成為許多癌細(xì)胞系靶向治療的理想選擇[6]。雖然一些研究已經(jīng)證明倍半萜內(nèi)酯對(duì)于人類各種細(xì)胞系的抗癌活性[7],但是對(duì)于頭頸部鱗癌的作用還未知。本文初步探討了Akt對(duì)于UM-SCC-10A細(xì)胞的抑瘤效果及其機(jī)制,結(jié)果顯示Akt能夠明顯抑制UM-SCC-10A細(xì)胞增殖,并隨濃度增加而增強(qiáng)。
Tab.2 The apoptotic associated protein expression after 48-hour treatment with different concentrations of Akt表2 不同濃度Akt作用48 h后UM-SCC-10A細(xì)胞凋亡相關(guān)蛋白蛋白表達(dá)(n=5,)
Tab.2 The apoptotic associated protein expression after 48-hour treatment with different concentrations of Akt表2 不同濃度Akt作用48 h后UM-SCC-10A細(xì)胞凋亡相關(guān)蛋白蛋白表達(dá)(n=5,)
組別對(duì)照組(1)10 μmol/L Art組(2)20 μmol/L Art組(3)F Bcl-2 1.99±0.05 0.96±0.01a 0.44±0.06ab 860.153**cytochrome C 0.64±0.01 0.77±0.04a 1.01±0.04ab 89.981**組別對(duì)照組(1)10 μmol/L Art組(2)20 μmol/L Art組(3)F Bax 1.24±0.14 1.29±0.41a 1.73±0.16ab 14.185**procaspase-3 1.18±0.17 0.68±0.07a 0.15±0.02ab 67.933**caspase-3 0 0.17±0.01a 0.93±0.04ab 1 671.475**
3.2 Akt通過線粒體途徑誘導(dǎo)細(xì)胞凋亡細(xì)胞凋亡的發(fā)生有3種主要途徑:死亡受體途徑、線粒體途徑和內(nèi)質(zhì)網(wǎng)途徑[8]。Bcl-2家族蛋白是線粒體凋亡信號(hào)通路中的關(guān)鍵因子[9]。Bcl-2和Bax均為Bcl-2家族蛋白成員,Bax/Bcl-2的比值增加,使線粒體膜通透性增高,cytochrome C釋放,促發(fā)caspase級(jí)聯(lián)反應(yīng),導(dǎo)致caspase 3的活化,引起細(xì)胞不可逆的凋亡過程。已經(jīng)證明caspase 3是哺乳動(dòng)物細(xì)胞線粒體凋亡途徑中主要效應(yīng)因子[10]。本實(shí)驗(yàn)中Akt誘導(dǎo)UM-SCC-10A細(xì)胞發(fā)生凋亡且隨濃度增加有所增加,與光鏡下的形態(tài)學(xué)檢測(cè)結(jié)果吻合。Western blot分析指出Akt明顯地使Bcl-2表達(dá)下調(diào),Bax表達(dá)上調(diào),導(dǎo)致UM-SCC-10A細(xì)胞Bax/Bcl-2的比值增加,從而使線粒體膜通透性增高,通過觀察線粒體膜電位的變化可以證實(shí)Bcl-2介導(dǎo)的線粒體凋亡途徑。Cy?tochrome C的釋放增加了caspase 3的表達(dá),用cas?pase抑制劑后細(xì)胞凋亡數(shù)量明顯減少,說明Akt誘導(dǎo)的UM-SCC-10A細(xì)胞凋亡是通過caspase依賴的線粒體凋亡途徑實(shí)現(xiàn)的。
3.3 Akt通過誘導(dǎo)細(xì)胞周期阻滯抑制UM-SCC-10A細(xì)胞生長細(xì)胞增殖主要受到細(xì)胞周期的調(diào)節(jié),當(dāng)細(xì)胞周期中特殊的節(jié)點(diǎn)被阻滯則可能引起細(xì)胞凋亡[11]。腫瘤抑制基因P53可通過其靶基因P21直接抑制Cyclin D,從而引起細(xì)胞周期在G1期的阻滯[12]。本研究結(jié)果提示Akt可能通過上調(diào)P53及P21的表達(dá),抑制Cyclin D,導(dǎo)致UM-SCC-10A細(xì)胞在G1期發(fā)生阻滯,從而抑制UM-SCC-10A細(xì)胞的生長,而且caspase活化的抑制作用不會(huì)改變細(xì)胞周期的阻滯,說明Akt對(duì)UM-SCC-10A細(xì)胞生長的抑制不僅由細(xì)胞凋亡引起,還由細(xì)胞周期阻滯引起。
(圖1~4見插頁)
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(2015-01-06收稿2015-04-22修回)
(本文編輯李鵬)
The effects and mechanism of artesunate inhibiting the proliferation and inducing the apoptosis of UM-SCC-10A cells
ZHAO Yan,LI Lihua△,ZHAO Song
Scientific Experimental Center of Liaoning Medical University,Jinzhou 121001,China△
ObjectiveTo study the influence of artesunate(Akt)on the proliferation and apoptosis of human head and neck squamous cell carcinoma(HNSCC),and to explore its molecular mechanism thereof.MethodsThe HNSCC cell line,UM-SCC-10A cells,was cultured in vitro.The Inhibitory concentration 50(IC50)was examined by MTT assay.The cell mor?phological changes were observed under inverted light micro-scope after being interfered by 0,2.5,5,10,20 and 40 μmol/L Akt.Cell cycle changes and apoptosis were measured by flow cytometry.And the expression of cell cycle regulators and apop?totic associated protein were detected by Western blot assay.ResultsMTT assay demonstrated that Akt significantly inhib?ited the proliferation of UM-SCC-10A cells in dose-dependent manner.After UM-SCC-10A cells were treated with Akt for 48 h,IC50was 15.01 μmol/L.Morphological changes of cell apoptosis such as karyopyknosis and conglomeration were ob?served by Hoechst 33258 staining.Flow cytometry showed that the apoptosis was associated with cell cycle arrest during the G1 phase.Western blot analysis showed that p53 and p21 protein was up-regulated and Cyclin D protein was down-regulat?ed.Furthermore,results revealed that Bcl-2 associated X protein induced by a mitochondrial pathway,cytochrome C and caspase-3 were up-regulated,and Bcl-2 and procaspase-3 were down-regulated.The mitochondrial membrane potential was reduced.ConclusionArtesunate can induce apoptosis of UM-SCC-10A cells via a mitochondrial pathway,which was associated with cell cycle arrest in the G1 phase.As a result,artesunate has an obvious inhibitory effects on proliferation of UM-SCC-10A cells.
apoptosis;cell proliferation;head and neck neoplasms;Artesunate
R739.91
A
10.11958/j.issn.0253-9896.2015.09.004
遼寧省教育廳優(yōu)秀人才成長計(jì)劃項(xiàng)目(LJQ2012074)
遼寧錦州,遼寧醫(yī)學(xué)院科學(xué)實(shí)驗(yàn)中心(郵編121001)
趙艷(1973),女,本科,醫(yī)學(xué)碩士學(xué)位,主要從事中藥研究
△通訊作者E-mail:lilihua1018@sina.com