Wright K, Kolios G, Westwick J, Ward S G
Department of Pharmacy and Pharmacology, Bath University, Claverton Down, Bath, BA2 7AY, United Kingdom.
J Biol Chem. 1999 Jun 11;274(24):17193-201. doi: 10.1074/jbc.274.24.17193.
A combination of the pro-inflammatory cytokines interleukin (IL)-1alpha, interferon (IFN)-gamma, and tumor necrosis factor (TNF)-alpha induces nitric oxide synthase mRNA expression and nitric oxide (NO) generation in the human colon carcinoma cell line HT-29. This can be inhibited by pretreatment with IL-13 via a phosphatidylinositol (PI) 3-kinase-dependent mechanism (Wright, K., Ward, S. G., Kolios, G., and Westwick, J. (1997) J. Biol. Chem. 272, 12626-12633). Since NO has been implicated in regulating mechanisms leading to cell death, while activation of PI 3-kinase-dependent signaling cascades are thought to be involved with promoting cell survival events, we have investigated the outcome of these cytokine treatments on apoptosis and cell survival of HT-29 cells. Initiation of apoptosis can be achieved by the combinations of IFN-gamma/TNF-alpha, IFN-gamma/CD95, IL-1alpha/IFN-gamma, and IL-1alpha/IFN-gamma/TNF-alpha to varying extents. Induction of apoptotic markers by HT-29 cells in response to cytokine treatment is not dependent on NO production. Pretreatment with IL-13 protects against IL-1alpha/IFN-gamma/TNF-alpha- and IFN-gamma/TNF-alpha- as well as IFN-gamma/CD95-induced (but not IL-1alpha/IFN-gamma-induced) cell death. In addition, IFN-gamma/TNF-alpha and IL-1alpha/IFN-gamma/TNF-alpha stimulate activation of caspase-8 and caspase-3, which IL-13 pretreatment was able to partially inhibit and delay. IL-13 also stimulates activation of the major PI 3-kinase effector, protein kinase B. The PI 3-kinase inhibitors wortmannin and LY294002 inhibit IL-13 stimulation of protein kinase B as well as the cell survival effects of IL-13. These data demonstrate that cytokine-induced apoptosis of HT-29 cells is NO-independent and that the activation of a PI 3-kinase-dependent signaling cascade by IL-13 is a key signal responsible for the inhibition of apoptosis.
促炎细胞因子白细胞介素（IL）-1α、干扰素（IFN）-γ和肿瘤坏死因子（TNF）-α联合作用可诱导人结肠癌细胞系HT-29中一氧化氮合酶mRNA表达及一氧化氮（NO）生成。通过磷脂酰肌醇（PI）3-激酶依赖性机制，用IL-13预处理可抑制这一过程（赖特，K.，沃德，S.G.，科利奥斯，G.，和韦斯特威克，J.（1997年）《生物化学杂志》272，12626 - 12633）。由于NO被认为参与调节导致细胞死亡的机制，而PI 3-激酶依赖性信号级联的激活被认为与促进细胞存活事件有关，我们研究了这些细胞因子处理对HT-29细胞凋亡和细胞存活的影响。IFN-γ/TNF-α、IFN-γ/CD95、IL-1α/IFN-γ以及IL-1α/IFN-γ/TNF-α的联合作用在不同程度上均可引发凋亡。HT-29细胞对细胞因子处理的反应中凋亡标志物的诱导不依赖于NO的产生。用IL-13预处理可保护细胞免受IL-1α/IFN-γ/TNF-α、IFN-γ/TNF-α以及IFN-γ/CD95诱导的（但不包括IL-1α/IFN-γ诱导的）细胞死亡。此外，IFN-γ/TNF-α和IL-1α/IFN-γ/TNF-α刺激半胱天冬酶-8和半胱天冬酶-3的激活，IL-13预处理能够部分抑制并延迟这种激活。IL-13还刺激主要的PI 3-激酶效应物蛋白激酶B的激活。PI 3-激酶抑制剂渥曼青霉素和LY294002抑制IL-13对蛋白激酶B的刺激以及IL-13的细胞存活效应。这些数据表明，细胞因子诱导的HT-29细胞凋亡不依赖于NO，并且IL-13激活PI 3-激酶依赖性信号级联是抑制凋亡的关键信号。
