Department of Gastroenterologic Surgery, Division of Cancer Medicine, Graduate School of Medical Science, Kanazawa University, Ishikawa 920-8641, Japan.
J Exp Clin Cancer Res. 2010 Nov 17;29(1):149. doi: 10.1186/1756-9966-29-149.
Management of peritoneal dissemination is the most critical problem in gastric cancer. This study was performed to investigate the inhibitory effects of valproic acid (VPA) on a highly peritoneal-seeding cell line of human scirrhous gastric cancer, OCUM-2MD3, and to explore the mechanism and the potential of VPA.
The effects of VPA on the growth of OCUM-2MD3 cells were assessed by MTT assay. In addition, paclitaxel (PTX) was combined with VPA to evaluate their synergistic effects. HDAC1 and HDAC2 expression were evaluated by western blotting in OCUM-2MD3 cells and other gastric cancer cell lines (TMK-1, MKN-28). The acetylation status of histone H3 and α-tubulin after exposure to VPA were analyzed by western blotting. The activities of cell cycle regulatory proteins and apoptosis-modulating proteins were also examined by western blotting. The effects of VPA in vivo were evaluated in a xenograft model, and apoptotic activity was assessed by TUNEL assay.
OCUM-2MD3 cells showed high levels of HDAC1 and HDAC2 expression compared with TMK-1 and MKN-28. The concentration of VPA required for significant inhibition of cell viability (P < 0.05) was 5 mM at 24 h and 0.5 mM at 48 h and 72 h. The inhibition of VPA with PTX showed dose-dependent and combinatorial effects. VPA increased acetyl-histone H3, acetyl-α-tubulin, and p21WAF1 levels accompanied by upregulation of p27, caspase 3, and caspase 9, and downregulation of bcl-2, cyclin D1, and survivin. In the xenograft model experiment, the mean tumor volume of the VPA-treated group was significantly reduced by 36.4%, compared with that of the control group at 4 weeks after treatment (P < 0.01). The apoptotic index was significantly higher in the VPA-treated group (42.3% ± 3.5%) than in the control group (7.7% ± 2.5%) (P < 0.001).
VPA induced dynamic modulation of histone H3 and α-tubulin acetylation in relation with the anticancer effect and the enhancement of PTX in the OCUM-2MD3 cell line. Therefore, VPA in combination with PTX is expected to be a promising therapy for peritoneal dissemination of scirrhous gastric cancer.
胃癌腹膜转移的管理是最关键的问题。本研究旨在探讨丙戊酸（VPA）对人弥漫型胃癌 OCUM-2MD3 高腹膜种植细胞系的抑制作用，并探讨 VPA 的机制和潜力。
通过 MTT 法评估 VPA 对 OCUM-2MD3 细胞生长的影响。此外，还评估了紫杉醇（PTX）与 VPA 联合应用的协同作用。通过 Western blot 法检测 OCUM-2MD3 细胞和其他胃癌细胞系（TMK-1、MKN-28）中 HDAC1 和 HDAC2 的表达。通过 Western blot 法分析 VPA 处理后组蛋白 H3 和α-微管蛋白的乙酰化状态。还通过 Western blot 法检测细胞周期调节蛋白和凋亡调节蛋白的活性。通过体内移植瘤模型评估 VPA 的作用，并通过 TUNEL 法评估凋亡活性。
与 TMK-1 和 MKN-28 相比，OCUM-2MD3 细胞中 HDAC1 和 HDAC2 的表达水平较高。在 24 小时时，VPA 显著抑制细胞活力所需的浓度（P<0.05）为 5 mM，在 48 小时和 72 小时时为 0.5 mM。VPA 与 PTX 的抑制作用呈剂量依赖性和组合性。VPA 增加乙酰化组蛋白 H3、乙酰化α-微管蛋白和 p21WAF1 水平，同时上调 p27、caspase 3 和 caspase 9，下调 bcl-2、cyclin D1 和 survivin。在移植瘤模型实验中，与对照组相比，治疗 4 周后 VPA 治疗组的平均肿瘤体积显著减少 36.4%（P<0.01）。VPA 治疗组的凋亡指数明显高于对照组（42.3%±3.5%比 7.7%±2.5%）（P<0.001）。
VPA 诱导组蛋白 H3 和α-微管蛋白乙酰化的动态调节与 OCUM-2MD3 细胞系的抗癌作用和 PTX 的增强有关。因此，VPA 联合 PTX 有望成为弥漫型胃癌腹膜转移的一种有前途的治疗方法。
