LY294002 may overcome 5-FU resistance via down-regulation of activated p-AKT in Epstein-Barr virus-positive gastric cancer cells.
LY294002 may overcome 5-FU resistance via down-regulation of activated p-AKT in Epstein-Barr virus-positive gastric cancer cells.
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DOI：
10.1186/1471-2407-10-425
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发表时间：
2010-08-13
期刊：
影响因子：
3.8
通讯作者：
Kang JH
中科院分区：
文献类型：
--
作者：
Shin JY;Kim JO;Lee SK;Chae HS;Kang JH
由于EBV相关胃癌具有不同于EBV（-）胃癌的独特特征，因此EBV被认为在胃癌发生中起关键作用。据报道，EBV转化的肿瘤细胞中的病毒潜伏膜蛋白2A（LMP 2A）激活磷脂酰肌醇3-激酶（PI 3 K）/AKT通路，其提供存活信号和对细胞毒性抗癌药物的化学抗性。本研究旨在探讨5-FU与PI 3 K选择性抑制剂LY 294002（LY）单独或联合应用对EBV阳性胃癌细胞株SNU-719的增殖抑制作用及细胞周期的影响。MTS法测定5-FU和LY单药及序贯联合用药后的细胞毒活性。Western blot检测5-FU和LY单用及序贯联合应用时，不同浓度组p-AKT、p-NFkB、p-p53和bcl-2的表达。我们还使用流式细胞术研究了对细胞凋亡和细胞周期分布的影响。进行LMP 2A siRNA抑制以确认降低的5-FU活性和p-AKT的逆转。当5-FU与LY序贯联合时，联合指数（CI）值表明具有协同抗增殖作用。5-FU单独处理可上调p-AKT和p-NFκB的表达，而5-FU和LY序贯处理可降低p-AKT和p-NFκB的表达。5-FU与LY联合应用时，G 0/G1期细胞数和亚G1期细胞数（%）增加。当5-FU加入到转染LMP 2A siRNA的细胞中时，其抗增殖作用增强，p-AKT表达降低。5-FU与LY序贯联合用药组p-p53表达较5-FU单药组明显增强，bcl-2表达较5-FU单药组明显减弱。这些数据表明，5-FU和LY的顺序组合诱导协同细胞毒性，并通过下调激活的p-AKT和EBV胃癌细胞系SNU-719中的细胞凋亡来克服5-FU的内在和获得性耐药性。
As EBV-associated gastric cancer has unique features that are different from EBV (-) gastric cancer, EBV is considered to have a key role in gastric carcinogenesis. It has been reported that viral latent membrane protein 2A (LMP2A) in EBV-transformed tumor cells activates the phosphatidylinositol 3-kinase (PI3K)/AKT pathway, which provides a survival signal and chemo-resistance to cytotoxic anti-cancer drugs. This study was to evaluate anti-proliferative effect and cell cycle change when 5-FU and LY294002 (LY), a selective inhibitor of PI3K, were treated separately or combined with different schedules in EBV positive gastric cancer cell line, SNU-719. After single treatment and sequential combination of 5-FU and LY, cytotoxic activity was measured by MTS assay. When 5-FU and LY were treated in single and sequential combinations, the expression of p-AKT, p-NFkB, p-p53 and bcl-2 was observed on different concentrations by Western blot analysis. We also investigated the effect on apoptosis and cell cycle distribution using flow cytometry. The LMP2A siRNA inhibition was done to confirm the reversal of decreased 5-FU activity and p-AKT. When 5-FU was sequentially combined with LY, the combination index (CI) value indicated synergistic anti-proliferative effect. The expression of p-AKT and p-NFκB was upregulated by 5-FU alone but sequential treatment of 5-FU and LY decreased the expression of both p-AKT and p-NFκB. When 5-FU was combined with LY, G0/G1 and sub G1 cell population (%) increased. When 5-FU was added to the cells transfected with LMP2A siRNA, its anti-proliferative effect increased and the expression of p-AKT decreased. In sequential combination of 5-FU and LY, the expression of p-p53 was increased and bcl-2 expression was diminished compared to 5-FU alone. These data suggest that sequential combination of 5-FU and LY induce synergistic cytotoxicity and overcome intrinsic and acquired resistance of 5-FU via downregulation of activated p-AKT and mitochondria-dependent apoptosis in EBV gastric cancer cell line, SNU-719.
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