魯華,秦?zé)睿季碍?,王艷林
(三峽大學(xué)腫瘤微環(huán)境與免疫治療湖北省重點實驗室,湖北宜昌443002)
·論著·
力達(dá)霉素對人宮頸癌Caski細(xì)胞增殖的影響及其機(jī)制
魯華,秦?zé)?,占景瓊,王艷林
(三峽大學(xué)腫瘤微環(huán)境與免疫治療湖北省重點實驗室,湖北宜昌443002)
目的探討力達(dá)霉素對人宮頸癌Caski細(xì)胞增殖的影響及其可能的機(jī)制。方法將對數(shù)生長期的人宮頸癌Caski細(xì)胞隨機(jī)分為低、中、高濃度組及對照組,低、中、高濃度組均加入含力達(dá)霉素的RPMI 1640完全培養(yǎng)基100 μL,分別調(diào)整其終濃度為1、2.5、5 ng/mL,對照組僅加入等體積RPMI 1640完全培養(yǎng)基。作用24 h,采用MTT法檢測細(xì)胞增殖能力(以吸光度值表示),計算細(xì)胞生存率;采用流式細(xì)胞術(shù)檢測細(xì)胞周期及線粒體膜電位降低比例;透射電子顯微鏡下觀察細(xì)胞形態(tài)學(xué)改變,計算細(xì)胞凋亡率及裂亡率。結(jié)果低、中、高濃度組細(xì)胞增殖能力及細(xì)胞生存率均低于對照組,且高濃度組降低更明顯(P均<0.01)。對照組及中濃度組S期細(xì)胞比例均高于低、高濃度組(P均<0.05)。低、中、高濃度組G0/G1期細(xì)胞比例均低于對照組,G2/M期細(xì)胞比例均高于對照組,且中、高濃度組變化更明顯(P均<0.05)。低、中、高濃度組及對照組細(xì)胞線粒體膜電位降低比例分別為(34.77±5.33)%、(37.87±5.73)%、(18.37±3.91)%、(4.17±0.65)%;低、中、高濃度組細(xì)胞線粒體膜電位降低比例均高于對照組,且低、中濃度組均高于高濃度組(P均<0.05)。透射電鏡下可見對照組細(xì)胞形態(tài)正常,低、中、高濃度組存在多種形態(tài)的死亡細(xì)胞,包括凋亡、壞死、裂亡的細(xì)胞。對照組及高、低、中濃度組細(xì)胞凋亡率及裂亡率均依次升高,兩組間比較P均<0.05。結(jié)論力達(dá)霉素可抑制人宮頸癌Caski細(xì)胞增殖,并呈濃度依賴性,其機(jī)制可能與誘導(dǎo)細(xì)胞凋亡或裂亡有關(guān)。
宮頸癌;力達(dá)霉素;人宮頸癌Caski細(xì)胞;細(xì)胞凋亡;細(xì)胞裂亡;線粒體膜電位
力達(dá)霉素是一種從鏈霉菌中分離的大分子肽類抗生素[1],對多種腫瘤(如肺癌、胰腺癌、肝癌等)具有強(qiáng)烈的細(xì)胞毒作用[2~6],其在細(xì)胞水平上的抗腫瘤活性顯著高于臨床上常用的抗腫瘤藥物,如阿霉素、絲裂霉素C、甲氨蝶呤等。研究表明,力達(dá)霉素可抑制肺癌、結(jié)腸癌、乳腺癌、胃癌、肝癌等細(xì)胞移植后的裸鼠成瘤能力,并通過多種機(jī)制抑制腫瘤生長,且可能對腫瘤細(xì)胞的增殖具有特異性影響[2~5]。2015年3月~2016年6月,本研究觀察了力達(dá)霉素對人宮頸癌Caski細(xì)胞增殖的影響,現(xiàn)分析結(jié)果并探討其可能的機(jī)制。
1.1 材料 細(xì)胞:人宮頸癌Caski細(xì)胞購于武漢大學(xué)細(xì)胞典藏中心,由三峽大學(xué)腫瘤微環(huán)境與免疫治療湖北省重點實驗室傳代保存。主要藥物及試劑:力達(dá)霉素由中國醫(yī)學(xué)科學(xué)院生物技術(shù)研究所甄永蘇院士惠贈,MitoProbe TM JC-1流式細(xì)胞術(shù)檢測試劑盒及RPMI 1640完全培養(yǎng)基均購于美國Invitrogen公司。主要儀器:全波長酶標(biāo)儀購于美國Thermo Fisher公司;H-7500透射電子顯微鏡購于日本日立公司;超薄切片機(jī)購于德國萊卡公司;EPICSXL-4流式檢測儀購于美國Beckman-coulter公司。
1.2 細(xì)胞培養(yǎng)與分組處理 取對數(shù)生長期的人宮頸癌Caski細(xì)胞,以3 000個/孔接種至96孔板,采用RPMI 1640完全培養(yǎng)基,于37 ℃、5% CO2培養(yǎng)箱中培養(yǎng)20 h。將人宮頸癌Caski細(xì)胞隨機(jī)分為低、中、高濃度組及對照組,低、中、高濃度組均加入含力達(dá)霉素的RPMI 1640完全培養(yǎng)基100 μL,分別調(diào)整其終濃度為1、2.5、5 ng/mL,對照組僅加入等體積RPMI 1640完全培養(yǎng)基,37 ℃、5% CO2培養(yǎng)箱中培養(yǎng)。每組設(shè)置4個復(fù)孔。
1.3 細(xì)胞增殖情況檢測 采用MTT法。取各組作用24 h細(xì)胞,每孔加入含0.5% MTT的RPMI 1640完全培養(yǎng)基(終濃度為250 μg/mL),繼續(xù)培養(yǎng)4 h。棄上清,每孔加入250 μL二甲基亞砜,置搖床上低速振蕩10 min,充分溶解結(jié)晶物。采用酶聯(lián)免疫檢測儀測量490 nm波長處的吸光度(OD)值,以此表示細(xì)胞增殖能力,并計算細(xì)胞生存率。細(xì)胞生存率=OD藥物/OD對照×100%。
1.4 細(xì)胞周期檢測 采用流式細(xì)胞術(shù)。收集各組作用24 h細(xì)胞,離心棄上清,預(yù)冷PBS沖洗2次,預(yù)冷70%乙醇4 ℃固定30 min。2 000 r/min離心5 min,棄上清,1 mL PBS沖洗1次。采用含0.2% TritonX-100和100 μg/mL RNase的PBS混合液500 μL重懸細(xì)胞,加入碘化丙啶(50 μg/ mL)避光孵育30 min,300目尼龍網(wǎng)進(jìn)行過濾,上流式細(xì)胞儀檢測細(xì)胞周期。
1.5 細(xì)胞凋亡情況檢測 采用流式細(xì)胞術(shù)。收集各組作用24 h細(xì)胞,用預(yù)溫至37 ℃的培養(yǎng)基1 mL重懸細(xì)胞,邊振蕩邊加入2.5 mL熒光染料JC-1儲存液(終濃度2.5 μg/mL),37 ℃避光保存10 min。加入2 mL PBS至細(xì)胞懸液中,2 000 r/min離心5 min,棄上清,0.3 mL PBS重懸細(xì)胞。上流式細(xì)胞儀檢測細(xì)胞線粒體膜電位降低比例,以此反映細(xì)胞凋亡情況。
1.6 細(xì)胞形態(tài)學(xué)改變及死亡細(xì)胞分類 收集各組作用24 h細(xì)胞,2 000 r/min離心5 min,棄上清,戊二醛溶液固定,超薄切片機(jī)制片。以200目透射電鏡銅網(wǎng)為載體,隨機(jī)選取10目,采用透射電子顯微鏡在不同放大倍數(shù)下(×5 000、×6 000、×7 000)觀察細(xì)胞形態(tài)學(xué)改變,計數(shù)凋亡及裂亡細(xì)胞,計算細(xì)胞凋亡率及裂亡率。
2.1 各組細(xì)胞增殖情況比較 低、中、高濃度組細(xì)胞增殖能力及細(xì)胞生存率均低于對照組,且高濃度組降低更明顯(P均<0.01)。見表1。
2.2 各組細(xì)胞周期比較 對照組及中濃度組S期細(xì)胞比例均高于低、高濃度組(P<0.05或<0.01)。低、中、高濃度組G0/G1期細(xì)胞比例均低于對照組,G2/M期細(xì)胞比例均高于對照組,且中、高濃度組變化更明顯(P<0.05或<0.01)。見表2。
表1 各組細(xì)胞增殖情況比較
注:與對照組比較,*P<0.01;與高濃度組比較,#P< 0.01。
表2 各組細(xì)胞周期比較
注:與對照組比較,*P<0.05,#P<0.01;與低濃度組比較,△P<0.05,▽P<0.01;與中濃度組比較,▲P<0.05。
2.3 各組細(xì)胞凋亡情況比較 低、中、高濃度組及對照組細(xì)胞線粒體膜電位降低比例分別為(34.77±5.33)%、(37.87±5.73)%、(18.37±3.91)%、(4.17±0.65)%;低、中、高濃度組細(xì)胞線粒體膜電位降低的細(xì)胞比例均高于對照組,且低、中濃度組升高更明顯(P均<0.05);低、中濃度組細(xì)胞線粒體膜電位降低的細(xì)胞比例比較差異無統(tǒng)計學(xué)意義(P>0.05)。
2.4 各組細(xì)胞形態(tài)學(xué)變化 對照組細(xì)胞膜完整,向外形成大量纖細(xì)突起的微絨毛;細(xì)胞質(zhì)染色正常,可見線狀、長桿狀線粒體;細(xì)胞核常染色質(zhì)(低電子密度)、異染色質(zhì)(高電子密度)分布均勻。低、中、高濃度組存在多種形態(tài)的死亡細(xì)胞,包括凋亡、壞死、裂亡的細(xì)胞。死亡細(xì)胞的主要特點:①凋亡中期細(xì)胞體積變小,細(xì)胞核深染,異染色質(zhì)邊集,核膜和細(xì)胞質(zhì)膜完整,細(xì)胞質(zhì)內(nèi)可見空泡形成,細(xì)胞膜上可見以發(fā)芽、起泡等方式形成的多個球形突起。凋亡晚期細(xì)胞體積進(jìn)一步變小,細(xì)胞質(zhì)少而深,細(xì)胞體周圍可見多個球形突起脫落形成的一些大小不等的凋亡小體。②壞死早期細(xì)胞核染色質(zhì)邊集,核中部電子密度低;細(xì)胞質(zhì)結(jié)構(gòu)崩解,呈顆粒狀;線粒體、內(nèi)質(zhì)網(wǎng)崩解形成空泡狀結(jié)構(gòu),可見其中含有中等電子密度的無定形電子致密物。壞死晚期細(xì)胞膜破裂,細(xì)胞質(zhì)逸出;細(xì)胞微絨毛消失,細(xì)胞質(zhì)結(jié)構(gòu)崩解,呈疏松顆粒狀;細(xì)胞器崩解空泡形成,染色質(zhì)變淡呈顆粒狀凝集,只可見到細(xì)胞核輪廓。③裂亡早期細(xì)胞體積變大,細(xì)胞有絲分裂異常形成大小不等多個細(xì)胞核。裂亡晚期細(xì)胞體積進(jìn)一步變大,細(xì)胞表面光滑,微絨毛消失,細(xì)胞質(zhì)內(nèi)充滿線粒體,內(nèi)質(zhì)網(wǎng)腫脹崩解形成的空泡狀結(jié)構(gòu);細(xì)胞核常染色質(zhì)與異染色質(zhì)差異消失,呈砂礫樣改變。
2.5 各組細(xì)胞凋亡率及裂亡率比較 對照組及高、低、中濃度組細(xì)胞凋亡率依次升高,對照組及低、中、高濃度組細(xì)胞裂亡率依次升高,兩組間比較P<0.05或<0.01。見表3。
表3 各組細(xì)胞凋亡率及裂亡率比較
注:與對照組比較,*P<0.05,#P<0.01;與低濃度組比較,△P<0.05,▽P<0.01;與中濃度組比較,▲P<0.05,▼P<0.01。
力達(dá)霉素是一種新型抗腫瘤藥物,其對肝癌BEL-7402細(xì)胞DNA、RNA合成具有強(qiáng)烈的抑制作用[7],對結(jié)腸癌HCT-116細(xì)胞具有明顯的細(xì)胞周期阻滯作用(阻滯于G2/M期)[8],并能顯著誘導(dǎo)早幼粒白血病HL-60細(xì)胞、胰腺癌細(xì)胞、骨髓瘤U266及SKO-007細(xì)胞凋亡[9~11],引起肝癌BEL-7420細(xì)胞發(fā)生裂亡[12]。本研究結(jié)果顯示,低、中、高濃度組細(xì)胞增殖能力及細(xì)胞生存率均低于對照組,且高濃度組降低更明顯;說明低濃度力達(dá)霉素處理24 h即能顯著抑制人宮頸癌Caski細(xì)胞增殖,且該作用具有濃度依賴性。
線粒體膜電位是指生物膜兩側(cè)離子濃度不同所產(chǎn)生的跨膜電位差,可反映線粒體功能的完整性,是評價線粒體功能的敏感指標(biāo)[13]。細(xì)胞死亡方式有凋亡和裂亡等不同形式[14,15],細(xì)胞凋亡時線粒體損傷發(fā)生在細(xì)胞核凋亡特征(染色質(zhì)濃縮、DNA斷裂)出現(xiàn)之前[16]。在凋亡因子的刺激下,線粒體膜通透性轉(zhuǎn)化孔增大,使內(nèi)膜離子濃度梯度消失、呼吸鏈?zhǔn)悸?lián),導(dǎo)致跨膜電位降低或耗散,促進(jìn)凋亡活性物質(zhì)如Cytc等從線粒體基質(zhì)中釋放進(jìn)入細(xì)胞質(zhì),激活Caspase級聯(lián)反應(yīng),最終引發(fā)細(xì)胞凋亡[17]。因此,線粒體膜電位降低是細(xì)胞凋亡早期的一個標(biāo)志性事件,線粒體膜電位降低細(xì)胞比例可反映細(xì)胞凋亡的程度[16]。本研究結(jié)果顯示,低、中、高濃度組線粒體膜電位降低的細(xì)胞比例均高于對照組,提示不同濃度的力達(dá)霉素均可導(dǎo)致線粒體膜電位顯著下降,并誘導(dǎo)細(xì)胞發(fā)生線粒體介導(dǎo)的凋亡。本研究中高濃度組細(xì)胞線粒體膜電位下降比例低于中、低濃度組,細(xì)胞線粒體膜電位下降比例并沒有隨力達(dá)霉素濃度的升高而升高,結(jié)合力達(dá)霉素對人宮頸癌Caski細(xì)胞的增殖抑制作用呈濃度依賴性這一結(jié)果,推測力達(dá)霉素除了誘導(dǎo)人宮頸癌Caski細(xì)胞凋亡外,還可能誘導(dǎo)Caski細(xì)胞發(fā)生其他類型的死亡。
1989年,Molz等[18]發(fā)現(xiàn)在一種對熱敏感的酵母突變株中,細(xì)胞分裂時染色體分離發(fā)生異常。此后一些學(xué)者便把這種在DNA發(fā)生損害時,細(xì)胞無法進(jìn)行完全分裂而導(dǎo)致出現(xiàn)四倍體或多倍體的現(xiàn)象稱為細(xì)胞有絲分裂災(zāi)變,這種有別于典型細(xì)胞凋亡特征的細(xì)胞死亡方式也被稱為裂亡[19]。裂亡的發(fā)生可能與細(xì)胞有絲分裂的異常,如中心體過度復(fù)制、多極性紡錘體形成、多核形成等有關(guān)[20],細(xì)胞周期檢測表現(xiàn)為S期和G2/M期阻滯[21]。本研究結(jié)果顯示,中、高濃度組G0/G1期細(xì)胞比例均低于對照組及低濃度組,G2/M期細(xì)胞比例均高于對照組及低濃度組,對照組及中濃度組S期細(xì)胞比例均高于低、高濃度組。說明力達(dá)霉素除了誘導(dǎo)人宮頸癌Caski細(xì)胞凋亡外,還可誘導(dǎo)細(xì)胞發(fā)生裂亡。
除了生化特征外,裂亡與凋亡細(xì)胞還具有各自不同的形態(tài)學(xué)特征。凋亡細(xì)胞染色質(zhì)凝集、邊緣化,細(xì)胞體皺縮、變圓,形成凋亡小體;裂亡的主要形態(tài)學(xué)特征包括有絲分裂異常,細(xì)胞體積變大,形成多核細(xì)胞。本研究透射電鏡觀察結(jié)果證實,力達(dá)霉素處理后的人宮頸癌Caski細(xì)胞形態(tài)學(xué)上發(fā)生上述凋亡、壞死及裂亡病理改變。本研究結(jié)果顯示,對照組及高、低、中濃度組細(xì)胞凋亡率依次升高,對照組及低、中、高濃度組細(xì)胞裂亡率依次升高;說明力達(dá)霉素濃度為2.5 ng/mL時對細(xì)胞凋亡的誘導(dǎo)作用最強(qiáng),濃度為5 ng/mL時對細(xì)胞裂亡的誘導(dǎo)作用最強(qiáng)。上述結(jié)果提示,不同濃度力達(dá)霉素誘導(dǎo)人宮頸癌Caski細(xì)胞死亡的模式也有所不同。
綜上所述,力達(dá)霉素可抑制人宮頸癌Caski細(xì)胞增殖,并呈濃度依賴性;其機(jī)制可能與誘導(dǎo)人宮頸癌Caski細(xì)胞凋亡或裂亡有關(guān)。
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EffectoflidamycinonproliferationofhumancervicalcancerCaskicells
LUHua,QINYe,ZHANJingqiong,WANGYanlin
(ChinaThreeGorgesUniversity,HubeiKeyLaboratoryofTumorMicroenvironmentandImmunotherapy,Yichang443002,China)
ObjectiveTo investigate the effect of lidamycin on the proliferation of human cervical cancer Caski cells and its underlying molecular mechanisms.MethodsHuman cervical cancer Caski cells were randomly divided the experimental groups (including the low-dose, medium-dose and high-dose groups) which were separately treated with 1, 2.5 and 5 ng/mL lidamycin (100 μL) for 24 h, and the control group which was added with the same volume of RPMI-1640. MTT assay was used to detect the inhibition rate of proliferation. The cell cycle and mitochondrial membrane potential of CasKi cells were measured by flow cytometry. Transmission electronic microscope was used to observe the morphological changes of Caski cells. We calculated the apoptosis rate and mitotic catastrophe rate.ResultsThe proliferation rate and survival rate of the experimental groups were significantly lower than those of the control group, and the decrease in the high-dose group was more significant (allP<0.05). The percentage of cells in the S phase of the control group and the medium-dose group was higher than those in the low-dose and high-dose groups (allP<0.05). The percentage of cells in the G0/G1phase of the experimental groups was lower than that of the control group and the percentage of cells in the G2/M phase was higher than that of the control group, especially in the medium-dose and high-dose groups (allP<0.05). The ratios of mitochondrial membrane potential decrease in the low-dose, medium-dose and high-dose groups and control group were 34.77%±5.33%, 37.87%±5.73%, 18.37%±3.91%, and 4.17%±0.65%, respectively. The mitochondrial membrane potential decreased ratios of the experimental groups were higher than that in the control group, especially in the low-dose and medium-dose groups (allP<0.05). Transmission electronic microscopy showed that the control group had normal morphology while the experimental groups had many forms of death cells, including apoptosis, necrosis and mitotic catastrophe. The apoptosis rate and mitotic catastrophe rate of the experimental groups were both higher than those of control group (bothP<0.05).ConclusionLidamycin can significantly inhibit the proliferation of Caski cells with an dose-dependent manner by inducing the apoptosis and mitotic catastrophe of cells.
cervical carcinoma; lidamycin; human cervical cancer Caski cells; apoptosis; mitotic catastrophe; mitochondrial membrane potential
國家自然科學(xué)基金資助項目(81372265)。
魯華(1978-),男,講師,研究方向為腫瘤病理學(xué)。E-mail: 4554080@qq.com
王艷林(1954-),男,教授,研究方向為腫瘤分子生物學(xué)。E-mail: 2244524933@qq.com
10.3969/j.issn.1002-266X.2017.44.001
R737.33
A
1002-266X(2017)44-0001-04
2017-02-09)