蟾蜍灵联合顺铂对人舌鳞状细胞癌Tca8113细胞增殖及凋亡的影响

目的 探讨蟾蜍灵联合顺铂对舌鳞状细胞癌（以下简称舌鳞癌）Tca8113细胞增殖、凋亡的影响及其机制。方法 培养人舌鳞癌Tca8113细胞株,取对数期细胞分为对照组、蟾蜍灵组、顺铂组、联合组。对照组加入RPMI 1640培养基;蟾蜍灵组分别加入10、20、40、80、160 nmol/L的蟾蜍灵;顺铂组分别加入2.5、5、10、20、40μg/m L的顺铂;联合组分别加入10、20、40、80、160 nmol/L的蟾蜍灵后按浓度对应加入2.5、5、10、20、40μg/m L的顺铂;MTT法检测各组细胞增殖抑制率,计算抑制细胞增殖50%的药物浓度（IC50）及联合指数（CI）。根据蟾蜍灵与顺铂48 h时的IC50选择三个药物组相应浓度亚组,即蟾蜍灵40 nmol/L组（蟾蜍灵亚组）,顺铂10μg/m L组（顺铂亚组）,蟾蜍灵40 nmol/L、顺铂10μg/m L组（联合亚组）,流式细胞术分析各亚组细胞凋亡情况,Western-Blot法检测各亚组Bax、Bcl-2、Caspase-3、细胞外调节蛋白激酶（Erk）及其磷酸化细胞外调节蛋白激酶状态（P-Erk）的表达。结果 与对照组相比,蟾蜍灵组、顺铂组、联合组细胞增殖受到抑制,且联合组增殖抑制率高于蟾蜍灵组与顺铂组,并呈时间-剂量依赖关系（P均〈0.05）。联合组联合指数（CI）均小于1。联合亚组细胞凋亡率高于蟾蜍灵亚组与顺铂亚组,三组与对照组相比,P均〈0.05。蟾蜍灵亚组、顺铂亚组、联合亚组Bax、Caspase-3蛋白表达高于对照组,其中联合亚组高于蟾蜍灵亚组和顺铂亚组;三个药物亚组P-Erk蛋白表达均低于对照组,其中联合亚组低于蟾蜍灵亚组和顺铂亚组;联合亚组Bcl-2表达低于对照组及蟾蜍灵亚组和顺铂亚组（P均〈0.05）。结论 蟾蜍灵与顺铂单用或联合应用均可抑制Tca8113细胞增殖,促进其凋亡,联用效果更强;其作用机制可能与调节细胞凋亡相关蛋白表达、抑制Erk信号通路有关。     

热疗联合表柔比星对胃癌MGC803细胞的体外抑制及凋亡的影响

目的 观察表柔比星(EPI)温热化疗对人胃癌MGC803细胞的体外抑制及凋亡的影响,探讨其作用机制.方法 采用四氮甲唑蓝(MTT)法确定作用48 h抑制率为50%的药物浓度作为实验的工作浓度.以48 h的IC50的药物浓度进行化疗或与热疗的联合,热疗选择温度为43℃,体外作用于MGC803细胞,实验分四组:对照组(C)、热疗组(H)、化疗组(D)、热化疗组(HD).MTT法检测各处理组对肿瘤细胞增殖的抑制作用;应用RT-PCR观察各处理组诱导MGC803细胞凋亡的作用及对Caspase-3和Bcl-2表达变化的影响.结果 单纯热疗和化疗对MGC803细胞系均有抑制作用(P<0.05);EPI温热化疗可明显增强EPI对MGC803细胞的抑制作用(P<0.05);与对照组比,热疗组、化疗组及热化疗组细胞凋亡率均较对照组显著升高,各组之间均有差异(P<0.05);Bcl-2表达下调、Caspase-3表达上调,各组之间均有差异(P<0.05).Caspase-3与Bcl-2蛋白的表达呈明显负相关(r=-0.990,n=12),细胞凋亡率与Bcl-2蛋白表达负相关(r=-0.924,n=12),而与Caspase-3蛋白表达正相关(r=0.891,n=12).结论 EPI联合热疗能显著抑制MGC803细胞生长并诱导细胞凋亡,可能与下调Bcl-2,上调Caspase-3的表达及二者相互作用有关.     

花青素协同奥沙利铂对人结肠癌HCT116细胞增殖及凋亡的影响

目的 探究花青素协同奥沙利铂对人结肠癌HCT116细胞增殖及凋亡的机制。方法 体外培养人结肠癌HCT116细胞,并分为:对照组、花青素组、奥沙利铂组、联合组;采用MTT法检测花青素、奥沙利铂单药及联合使用对人结肠癌HCT116细胞的增殖情况;采用克隆形成实验检测细胞生长情况;采用流式细胞仪检测各组细胞凋亡情况;采用Western blot检测TGF-βsmad信号通路相关蛋白及增殖凋亡蛋白表达情况。结果 由MTT实验发现,花青素对人结肠癌HCT116细胞48 h的半数致死浓度(IC50)为100 g/L,奥沙利铂人结肠癌HCT116细胞48 h的IC50为0. 01 g/L,两者联合使用其半数致死浓度显著下降为60 g/L和0. 6 g/L。相比对照组,花青素组和奥沙利铂组克隆形成率、Ki67蛋白相对表达、Bcl-2蛋白相对表达水平显著降低(P 0. 01),人结肠癌HCT116细胞凋亡率、Bax蛋白相对表达、Smad2和p-Smad2蛋白相对表达、Smad3和p-Smad3蛋白相对表达、TGF蛋白相对表达均显著升高(P 0. 01);相比花青素组和奥沙利铂组,联合组克隆形成率、Ki67蛋白相对表达、Bcl-2蛋白相对表达水平显著降低(P 0. 01),人结肠癌HCT116细胞凋亡率、Bax蛋白相对表达、Smad2和p-Smad2蛋白相对表达、Smad3和p-Smad3蛋白相对表达、TGF蛋白相对表达均显著升高(P 0. 01)。结论 花青素协同奥沙利铂可以促进人结肠癌HCT116细胞的凋亡并抑制其增殖,且作用效果显著优于使用单一药物,其作用机制可能是通过调节TGF-β/Smad信号通路实现。     

PCSK9-siRNA在抗ox-LDL诱导的THP-1源性巨噬细胞凋亡中对Bax、Bcl-2表达的影响

目的 研究PCSK9siRNA在抗ox-LDL诱导的THP-1源性巨噬细胞凋亡中对Bax、Bcl-2表达的影响.方法 用不同浓度ox-LDL处理THP-1源性巨噬细胞不同时间,免疫印迹法检测Bax、Bcl-2表达变化.应用Lipofectamine2000分别转染30、50 nmol/L和80 nmol/L PCSK9 siRNAs 进THP-1 源性巨噬细胞中,作用24 h后加入ox-LDL 处理48 h,免疫印迹法分析细胞Bax、Bcl-2表达,Hoechst33258染色观察形态评价细胞凋亡.结果 随着ox-LDL浓度的增加,Bax蛋白表达上调,而Bcl-2蛋白表达下调,呈浓度依赖性,80 μg/mL ox-LDL处理组作用最为明显;80 μg/mL ox-LDL处理THP-1源性巨噬细胞不同时间后,Bax蛋白表达上调,而Bcl-2蛋白表达下调,呈时间依赖性,48 h处理组作用最为明显;PCSK9 siRNA能明显下调Bax蛋白表达,上调Bcl-2蛋白表达,且均呈浓度依赖性;Hoechst33258染色显示,PCSK9 siRNA转染组细胞凋亡明显减少.结论 PCSK9 siRNA在抗ox-LDL诱导的THP-1 源性巨噬细胞凋亡中下调促凋亡蛋白Bax表达,上调抗凋亡蛋白Bcl-2表达.     

汉防己甲素联合顺铂对 NCI-H446细胞的影响及相关机制分析

目的：研究汉防己甲素(tetrandrine,TET)联合顺铂(cisplatin,DDP)对人小细胞肺癌细胞株 NCI-H446体外抗肿瘤效果,探讨 TET 增强 NCI-H446细胞对 DDP 敏感性的可能机制。方法体外培养人小细胞肺癌株 NCI-H446;药物作用48 h 后,采用 CCK-8法测定各组细胞活力;Edu 染色观察各组细胞增殖情况;Hoechst 染色检测各组细胞凋亡情况;Western blot 检测各组磷酸化Akt、Bax、Bcl-2、cleaved-caspase-3、LC3等蛋白表达水平变化。结果低浓度的 TET 与 DDP 联合后可有效抑制 NCI-H446细胞株的增殖,诱导其凋亡;联合组半数抑制浓度较单药组显著降低;联合组磷酸化 Akt 表达显著下降,Bax、cleaved-caspase-3表达显著提高,抗凋亡蛋白 Bcl-2表达下降;自噬相关蛋白 LC3表达明显上调。结论低浓度 TET 与顺铂具有协同效应,其机制可能是通过上调促凋亡蛋白 Bax,下调抗凋亡蛋白 Bcl-2来诱导细胞凋亡;并且自噬可能在其中发挥重要作用。     

中药槐耳诱导人胃癌细胞MGC803凋亡的实验研究

[目的]探讨槐耳、顺铂对人胃癌细胞株MGC803细胞增殖和凋亡的影响以及槐耳诱导人胃癌MGC803细胞凋亡的机制。[方法]以不同浓度的槐耳、顺铂以及联合用药分别作用于体外培养的人胃癌细胞MGC803,MTT法检测MGC803凋亡的情况,倒置显微镜观察其形态的变化,流式细胞术检测早期细胞凋亡情况;Western blot法检测槐耳处理24h后基质金属蛋白酶(MMP)-2的表达情况。[结果]MTT实验显示槐耳及顺铂均可抑制MGC803细胞的生长,呈时间及浓度依赖性;流式细胞仪可检测到MGC803细胞凋亡率明显增加,呈时间及浓度依赖性;槐耳能降低MGC803细胞中MMP-2蛋白的表达水平,并呈浓度依赖性。[结论]槐耳可在体外抑制人胃癌细胞MGC803的生长,并促进它的凋亡,且机制可能与抑制MMP-2的表达有关。联合使用槐耳和化疗药物可能会更有效发挥槐耳抗肿瘤增值的作用。     

大蒜素对卵巢癌耐顺铂细胞株SKOV-3/DDP增殖的影响及机制

目的探讨大蒜素对卵巢癌耐顺铂细胞株SKOV-3/DDP凋亡的影响及机制。方法将SKOV-3/DDP细胞随机分为四组,大蒜素组加入40μg/mL的大蒜素,顺铂组加入40μg/mL的顺铂,联合组加入大蒜素和顺铂各40μg/mL,对照组不干预。各组分别培养24、48 h。采用MTT法检测各组细胞增殖抑制率;RT-PCR法测定Bax、Bcl-2mRNA表达;Western blot法测定Bax、Bcl-2蛋白表达。结果顺铂组、大蒜素组、联合组各时点(24 h、48 h)增殖抑制率明显高于对照组,联合组明显高于大蒜素组、顺铂组,P均<0.05。顺铂组、大蒜素组、联合组各时点Bax mR-NA和蛋白水平明显高于对照组,大蒜素组、联合组Bcl-2 mRNA和蛋白水平明显低于对照组,P均<0.05;顺铂组48 h Bcl-2蛋白明显高于对照组,P<0.05;联合组各时点Bax mRNA和蛋白水平明显高于、Bcl-2 mRNA和蛋白水平明显低于对照组,P均<0.05。结论大蒜素诱导SKOV-3/DDP凋亡作用优于顺铂,两者联合具有协同作用,其机制可能为上调Bax表达和下调Bcl-2表达有关。     

姜黄素对人胃癌MGC803的体外抑制作用

[目的]观察姜黄素对人胃癌MGC803细胞的生长抑制作用,观察药物作用时间浓度的关系并探究其诱导凋亡的机制。[方法]MTT法建立细胞剂量效应、时间效应曲线;caspase 3、caspase 9活性检测试剂盒及Western Blot实验分别检测caspase 3、caspase 9活性变化情况和Bax、Bcl-2蛋白表达情况。[结果]姜黄素对人胃癌MGC803细胞有明显的剂量-时间依赖效应;姜黄素干预后,caspase 3、caspase 9活性明显升高;Bcl-2蛋白水平显著下降,Bax蛋白表达明显升高。[结论]姜黄素在体外对人胃癌MGC803细胞的增殖具有抑制作用,其促凋亡可能是通过调控Bax、Bcl-2、caspase 3、caspase 9蛋白来实现的。     

脑通汤对缺氧/复氧大鼠海马神经元Bcl-2、Bax和Caspase-3表达的影响

目的探讨脑通汤对缺氧/复氧(H/R)大鼠海马神经元Bcl-2、Bax和半胱氨酸蛋白酶(Caspase)-3表达的影响及防治海马神经元凋亡的作用机制。方法取培养9 d的海马神经元,随机分为正常细胞组、H/R模型组、正常血清组、脑通汤大、中、小剂量含药血清组。除正常细胞组以外,各组均缺氧24 h再复氧2 h造模。采用免疫组化检测海马神经元Bcl-2、Bax蛋白表达;实时荧光定量PCR法检测Bcl-2、Bax、Caspase-3基因的表达。结果免疫组化显示:与正常细胞比较,模型组Bcl-2蛋白表达下降、Bax蛋白表达明显升高、Bcl-2/Bax比值下调(P0.05)。与模型组比较,脑通汤大、中、小剂量含药血清组Bcl-2蛋白表达及Bcl-2/Bax比值明显增高,Bax蛋白表达明显下降,呈剂量依赖性(P0.05);但正常血清组上述指标无显著变化(P0.05)。实时荧光定量PCR显示:Bcl-2、Bax mRNA趋势同蛋白表达一致,Caspase-3 mRNA趋势同Bax mRNA表达一致。结论脑通汤可通过上调Bcl-2蛋白及基因表达和Bcl-2/Bax比值,抑制Bax及Caspase-3的过度表达,从而抑制H/R海马神经元凋亡。     

Notch1表达对肾癌细胞生物学行为的影响

目的探讨Notch1表达对肾癌细胞生物学行为的影响。方法通过Western印迹检测Notch1在人正常肾小管上皮细胞HK-2,人肾癌细胞786-O,Caki-1,769-P,GRC-1及ACHN中的表达;siRNA Notch1及siRNA NC转染肾癌细胞48 h后,Western印迹及RT-PCR检测转染情况,MTT法及Hoechst染色检测细胞活力及凋亡情况,Transwell法检测细胞迁移侵袭能力,Western印迹检测Bax,Bcl-2,基质金属蛋白酶(MMP)2,MMP9蛋白表达。结果 HK-2细胞中Notch1蛋白表达量显著低于5株肾癌细胞786-O,769-P,GRC-1,Caki-1及ACHN,且在Caki-1中Notch1表达量最高,因此作为后续实验的细胞株。siRNA Notch1及siRNA NC转染肾癌细胞48 h后,与siRNA NC组比较,siRNA Notch1组Notch1蛋白及mRNA表达量下调,细胞活力降低,细胞凋亡率提高,细胞侵袭数目减少,Bax表达量上调,Bcl-2、MMP2及MMP9表达量下调(P<0.01)。结论 Notch1低表达能显著抑制肾癌细胞Caki-1的恶性生物学行为,可能与调控细胞凋亡蛋白及下调MMPs表达有关。     

蟾毒灵介导JNK信号通路诱导人胰腺癌细胞的凋亡

目的:研究蟾毒灵诱导人胰腺癌细胞凋亡以及凋亡相关基因表达的JNK信号转导通路,揭示其抗胰腺癌的部分机制.方法:MTT法观察蟾毒灵对人胰腺癌BxPC-3细胞的生长抑制作用;0.16、0.32、0.64mg/L蟾毒灵分别作用人胰腺癌BxPC-3细胞48h后,流式细胞仪(flow cytometry,FCM)检测细胞周期和细胞凋亡;Western印迹法检测蟾毒灵作用BxPC-3细胞后SAPK/JNK信号通路的激活情况,荧光定量PCR检测Survivin基因mRNA的表达水平;并比较阻断JNK信号通路后丹参酮ⅡA对胰腺癌细胞凋亡Survivin基因mRNA的表达.结果:MTT法测得蟾毒灵对人胰腺癌BxPC-3细胞具有显著的抑制作用,其作用效果与剂量和作用时间成正相关;0.16、0.32、0.64mg/L浓度蟾毒灵作用人胰腺癌细胞后的细胞凋亡率分别为19.36%±0.39%、40.69%±0.44%、59.63%±1.14%,与对照组2.24%±0.37%比较均有显著性差异(P<0.01);蟾毒灵作用人胰腺癌细胞1h后JNK信号通路被激活,2h达峰值;阻断JNK信号通路后,凋亡率明显降低(P<0.01);0.32mg/L蟾毒灵作用人胰腺癌细胞48h后Survivin mRNA的表达明显下降;阻断JNK信号通路后,蟾毒灵作用人胰腺癌细胞的Survivin mRNA的表达明显上升.结论:蟾毒灵通过JNK信号转导通路下调人胰腺癌BxPC-3细胞Survivin mRNA的表达,可能是其诱导胰腺癌细胞凋亡的机制.     

蟾蜍毒素对人胃癌细胞凋亡的诱导机制

目的:研究蟾蜍毒素诱导人胃癌细胞MGC803凋亡及对凋亡因子Livin、caspase-3的影响.方法:应用MTT法检测10、20、40、80、160nmol/L蟾蜍毒素对胃癌细胞MGC803增殖抑制作用:瑞氏-吉姆萨染色法观察细胞形态学的变化;流式细胞术分析周期阻滞和细胞凋亡;Western blot法检测Livin...     

Bufalin Induces the Apoptosis of Acute Promyelocytic Leukemia Cells via the Downregulation of Survivin Expression

Background and Aims: Bufalin is a cardiotonic steroid isolated from the Chinese toad venom preparation Chan'su and has been shown to induce leukemia cell differentiation and apoptosis under certain experimental conditions. However, the detailed mechanism by which bufalin induces the apoptosis of acute promyelocytic leukemia cells is largely unexplored. Methods: The acute promyelocytic leukemia cell line NB4 was treated with bufalin, then the proliferation was evaluated by cell viability assay and apoptosis was detected by flow cytometry analysis. In addition, NB4 cells were treated by MEK inhibitor PD98059 in combination with bufalin, and the expression of survivin and activation of caspase-3 were detected by Western blot analysis. Results: Bufalin inhibited the proliferation and induced the apoptosis of NB4 cells in a dose- and time-dependent manner. Moreover, bufalin synergized with PD98059 to inhibit the proliferation and induce the apoptosis of NB4 cells, which was associated with the downregulation of survivin expression and the upregulation of caspase-3 activation. Conclusions: Bufalin is a potential regimen to be used in combination with conventional chemotherapeutic drugs to improve acute promyelocytic leukemia therapy.     

Bufalin Enhances the Cytotoxity of Human Multiple Myeloma Cells H929 to AKT Inhibitor MK2206: The Role of Protein AKT Phosphorylation

This study was purposed to investigate bufalin combined with AKT inhibitor MK2206 on growth inhibition and apoptosis of multiple myeloma cell line H929. CCK-8 assay and Annexin/PI staining were used to access the effects of bufalin and MK2206 in single or in combination, on inhibition of proliferation and induction of apoptosis in H929 cells. The apoptotic cells markedly increased after treated with nM bufalin and μM MK2206, including caspase3 and PARP1 proteins activated. The difference was statistically significant (P < 0.05) when compared with these drugs in single use. The apoptosis associated proteins and AKT/p-AKT proteins were determined by Western blots. We confirmed that AKT performed contradictory results in H929 with the two agents, and concluded p-AKT was vital in the synergy. The underlying mechanisms warrant further investigation.     

Down-regulation of Cbl-b by bufalin results in up-regulation of DR4/DR5 and sensitization of TRAIL-induced apoptosis in breast cancer cells

Purpose

TNF-related apoptosis-inducing ligand (TRAIL) is a potential cancer therapeutic agent that preferentially induces apoptosis in cancer cells. However, breast cancer cells are generally resistant to TRAIL. Bufalin is a major active ingredient of the traditional Chinese medicine ChanSu. The present study aimed to assess the synergistic effect of bufalin and TRAIL and elucidate the underlying mechanisms in breast cancer cells.

Methods

Cell proliferation and apoptosis were measured by MTT assay and flow cytometry, respectively. The expression of proteins was assayed by flow cytometry and/or Western blotting. Transfection studies were used to determine the involvement of DR4, DR5 and Cbl-b in the synergistic effect of bufalin and TRAIL.

Results

MCF-7 and MDA-MB-231 cells were resistant to TRAIL. Both cell lines were dramatically sensitized to TRAIL-induced apoptosis by bufalin. Further experiments indicated that bufalin up-regulated DR4 and DR5, activated ERK, JNK and p38 MAPK and down-regulated Cbl-b. Blocking the up-regulation of DR4 and DR5 by siRNA rendered cells less sensitive to apoptosis induced by the combination of bufalin and TRAIL. Inhibition of the activation of ERK, JNK and p38 MAPK by specific inhibitors attenuated DR4 and DR5 up-regulation. Moreover, down-regulation of Cbl-b by shRNA led to stronger activation of ERK, JNK and p38 MAPK, more up-regulation of DR4 and DR5, and a stronger synergistic effect of bufalin and TRAIL.

Conclusions

Bufalin enhanced TRAIL-induced apoptosis by up-regulating the expression of DR4 and DR5. Bufalin-induced down-regulation of Cbl-b contributed to the up-regulation of DR4 and DR5, which might be partially mediated by the activation of ERK, JNK and p38 MAPK.     

大蒜素联合奥沙利铂对HCT-8细胞生长和增殖的影响及机制

目的探讨大蒜素与奥沙利铂联合应用治疗大肠癌的可行性及机制。方法将大蒜素和奥沙利铂单独及联合作用于人大肠癌细胞系HCT-8细胞,MTT法检测HCT-8细胞生长抑制率,流式细胞术检测细胞周期及细胞凋亡率,免疫细胞化学SP法检测Caspase-3蛋白表达,苏木素复染观察异常分裂细胞。结果联合大蒜素后,奥沙利铂对HCT-8的增殖抑制作用增强（P〈0．01）;细胞阻滞于G2／M期,且凋亡率升高（P〈0．01）;Caspase-3表达上凋（P〈0．01）;异常分裂细胞数增多（P〈0．01）。结论大蒜素能增强HCT-8细胞对奥沙利铂的化疗敏感性,此可能与大蒜素对HCT-8细胞的抑制增殖、细胞周期阻滞及促进凋亡作用有关。     

Low-dose oxaliplatin enhances the antitumor efficacy of paclitaxel in human gastric cancer cell lines

BACKGROUND: The enhanced antitumor effect of paclitaxel when used with oxaliplatin in gastric cancer is reported, however the underlying biological mechanism is unknown. METHODS: We tested the cytotoxic activity, apoptosis, and mitotic catastrophe of paclitaxel and oxaliplatin in MKN-28 and MKN-45 gastric cancer cell lines. The modulation of survivin expression was determined by Western blotting. RESULTS: WST-1 assay indicated that paclitaxel plus oxaliplatin showed better cytotoxicity than paclitaxel alone, even when low concentrations of oxaliplatin were used. Flow cytometry analysis revealed significantly greater increases in apoptotic cells after treatment with paclitaxel followed by low-dose oxaliplatin (1 microM) than after any single-reagent regimen in the MKN-45 cell line. In MKN-28, a difference existed only between combination treatment and oxaliplatin treatment. Morphologic examination showed that the cells undergoing mitotic catastrophe were highest in the combination groups in the both cell lines. Downregulation of survivin expression was found by Western blotting with treatment by paclitaxel, oxaliplatin, or their combination. CONCLUSION: Our findings suggest that the mechanism of enhanced cytotoxicity might be through enhanced mitotic catastrophe and apoptosis, which is possibly due to chemotherapy-induced downregulation of surviving. The combination of paclitaxel and low-dose oxaliplatin should be incorporated into the design of a clinical trial.     

Protective effect of melatonin on oxaliplatin‐induced apoptosis through sustained Mcl‐1 expression and anti‐oxidant action in renal carcinoma Caki cells

Abstract: Melatonin is an indolamine initially found to be produced in the pineal gland but now known to be synthesized in a variety of other tissues as well. The mechanisms whereby melatonin regulates the apoptotic program remain only partially understood. Anti‐/pro‐apoptotic effects of exogenous melatonin on various stimuli‐mediated apoptosis were investigated in this report. We investigated the combined effect of melatonin and death receptor–mediated ligands (TNF‐α, TRAIL, and anti‐Fas antibody) or endoplasmic reticulum (ER) stress‐inducing agents (thapsigargin, brefeldin A, and tunicamycin) on apoptosis of cancer cells. Death receptor– or ER stress–induced apoptosis was not significantly influenced by melatonin treatment. However, pretreatment with melatonin significantly inhibited DNA damage–induced apoptosis and glutathione (GSH) depletion, suggesting the reactive oxygen species mediate oxaliplatin/etoposide‐induced apoptosis. Interestingly, we also found the involvement of myeloid cell leukemia‐1 (Mcl‐1) downregulation in oxaliplatin‐induced apoptosis; thus, pretreatment with melatonin inhibited Mcl‐1 downregulation, and ectopic expression of Mcl‐1 attenuated oxaliplatin‐induced apoptosis. Taken together, the results demonstrate that melatonin attenuates oxaliplatin‐induced apoptosis in cancer cells by inhibition of GSH depletion and Mcl‐1 downregulation.     

Clinical and experimental study of oxaliplatin in treating human gastric carcinoma

AIM: To evaluate the therapeutic effectiveness of oxaliplatin on human gastric carcinoma and to explore its mechanisms. METHODS: Twenty-two cases of stage IV gastric carcinoma received 4-6 (mean 4.6) cycles of first line combined chemotherapy with oxaliplatin (oxaliplatin 85 mg/m(2), iv, gtt, 1 h, d 1; leukovorin 200 mg/m(2), iv, gtt, 1 h, d 1 and d 2; 5-FU 300 mg/m(2),iv, d 1 and d 2, 5-FU, continuous iv, gtt, 48 h; 1 cycle/2 wk). Response rate, progression-free survival (PFS), total survival time, toxic side effects were evaluated. The inhibitory effect of oxaliplatin on human gastric cell line SGC-7901 was detected and IC(50) was calculated by MTT. Transmission electron microscopy, flow cytometry and TUNEL were performed to evaluate the apoptosis of cell line induced by the drug. The expression of Caspase-3 m-RNA was detected by RT-PCR. AC-DEVD-CHO, a Caspase-3 specific inhibitor, was used to elucidate the role of activated Caspase-3 in the process of apoptosis induced by oxaliplatin. RESULTS: Total response (complete and partial) occurred in 9 (40.9%) patients. Mean PFS was 4.2 mo and mean total survival time was 7.2 mo. Cumulative neurotoxicity (all grade I-II), vomiting and diarrhea, myelosuppression appeared in 93.5%, 20%, 32.9% patients, respectively. IC(50) was calculated to be 0.71 mg/L by MTT assay. A maximal inhibitory rate reached 85.3%. Apoptosis index was elevated after incubated with 1 mmol/L oxaliplatin for 30 min, but without statistic significance (P>0.05). However it could be detected at a much higher degree both by flowcytometry and by TUNEL with a statistical significance (68.47+/-7.92% and 8.23+/-2.67%, respectively, P<0.05) after incubated with 1 mmol/L oxaliplatin for 2 d. By means of RT-PCR, we detected an enhancement of Caspase-3 m-RNA expression induced by oxaliplatin which was also in positive correlation with the apoptotic level. AC-DEVD-CHO, a Caspase-3 specific inhibitor, could significantly inhibit and delay apoptosis induced by oxaliplatin. CONCLUSION: Oxaliplatin is effective and well-tolerated in patients with advanced gastric carcinoma. Oxaliplatin could significantly inhibit the growth of human gastric cell line SGC-7901. The induction of Caspase-3 m-RNA expression, activation of Caspase-3 and promotion of apoptosis may be some of the therapeutic mechanisms of oxaliplatin on gastric carcinoma. Annexin-V-fluorescein labeling flow cytometry is much more sensitive than TUNEL in detecting early stage apoptosis.