Department of General, Visceral and Transplantation Surgery, University of Heidelberg, Heidelberg, Germany.
Int J Oncol. 2012 Feb;40(2):427-35. doi: 10.3892/ijo.2011.1239. Epub 2011 Oct 21.
Histone deacetylase inhibitors have been found to have potent anticancer activities, partly induced by tumour cell apoptosis. The clearance of apoptotic tumour cells is an important mechanism of antitumour immune surveillance. The aim of this study was to assess the impact of 4-phenylbutyrate (4-PB) and its immunological effects on the macrophage clearance of apoptotic pancreatic ductal adenocarcinoma (PDAC) cells. To this end, a co-culture system of human macrophages from donors and PDAC patients, and PDAC cell lines (T3M4, PANC-1 and AsPC-1) was established to study the effect of 4-PB. Apoptosis and phagocytic activity were analysed using flow cytometry, and phagocytosis was confirmed by confocal microscopy. Further, p21 expression was quantified by immunoblot analysis. 4-PB treatment (0-10 mM) resulted in a dose-dependent induction of tumour cell apoptosis in two of the cell lines (T3M4 and PANC-1), but it also induced human macrophage apoptosis. The apoptotic effect of gemcitabine on PDAC cells was further enhanced by 4-PB. Moreover, 4-PB led to a dose-dependent overexpression of the cell cycle regulator p21 in tumour cells. In co-culture, apoptotic PDAC cells were phagocytosed by donor macrophages and phagocytosis was increased through tumour cell exposure to 4-PB and/or gemcitabine, whereas phagocytosis of PANC-1 cells was reduced using macrophages of PDAC patients treated with 4-PB. The 4-PB treatment induced human macrophage expression of the pro-angiogenic IL-8 and simultaneously inhibited inflammatory cytokine release through modulation of IL-10 and TNFα after phagocytosis of apoptotic PDAC cells. In conclusion, the 4-PB treatment activated tumour cell death in PDAC cells, resulting in tumour cell phagocytosis by macrophages. The latter were characterized by an anti-inflammatory and pro-angiogenic cytokine response demonstrating adverse, tumour-promoting effects of macrophages on tumour cells. Thus, the potential of 4-PB as an anticancer agent against PDAC cannot be reliably assessed without taking into account the complex tumour microenvironment.
组蛋白去乙酰化酶抑制剂已被发现具有很强的抗癌活性，部分原因是诱导肿瘤细胞凋亡。凋亡肿瘤细胞的清除是抗肿瘤免疫监视的重要机制。本研究旨在评估 4-苯丁酸（4-PB）及其对巨噬细胞清除凋亡胰腺导管腺癌（PDAC）细胞的免疫作用。为此，建立了供体和 PDAC 患者来源的人巨噬细胞与 PDAC 细胞系（T3M4、PANC-1 和 AsPC-1）的共培养系统，以研究 4-PB 的作用。使用流式细胞术分析细胞凋亡和吞噬活性，并通过共聚焦显微镜确认吞噬作用。进一步通过免疫印迹分析定量检测 p21 表达。4-PB 处理（0-10 mM）导致两种细胞系（T3M4 和 PANC-1）中的肿瘤细胞凋亡呈剂量依赖性诱导，但也诱导人巨噬细胞凋亡。4-PB 进一步增强了吉西他滨对 PDAC 细胞的凋亡作用。此外，4-PB 导致肿瘤细胞中细胞周期调节剂 p21 的表达呈剂量依赖性上调。在共培养中，凋亡的 PDAC 细胞被供体巨噬细胞吞噬，并且通过肿瘤细胞暴露于 4-PB 和/或吉西他滨，吞噬作用增加，而在用 4-PB 处理的 PDAC 患者的巨噬细胞中，对 PANC-1 细胞的吞噬作用降低。4-PB 处理诱导人巨噬细胞表达促血管生成的 IL-8，同时通过吞噬凋亡 PDAC 细胞后调节 IL-10 和 TNFα 的释放来抑制炎症细胞因子的释放。总之，4-PB 处理激活了 PDAC 细胞中的肿瘤细胞死亡，导致巨噬细胞吞噬肿瘤细胞。后者的特征是抗炎和促血管生成细胞因子反应，表明巨噬细胞对肿瘤细胞具有不利的促肿瘤作用。因此，在不考虑复杂的肿瘤微环境的情况下，4-PB 作为抗 PDAC 抗癌剂的潜力不能可靠评估。
