Prolyl Hydroxylase-3 Is Down-regulated in Colorectal Cancer Cells and Inhibits IKKβ Independent of Hydroxylase Activity
Prolyl Hydroxylase-3 Is Down-regulated in Colorectal Cancer Cells and Inhibits IKKβ Independent of Hydroxylase Activity
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DOI：
10.1053/j.gastro.2009.09.049
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发表时间：
2010-02-01
期刊：
影响因子：
29.4
通讯作者：
Fang, Jing
中科院分区：
文献类型：
--
作者：
Xue, Jing;Li, Xuebing;Fang, Jing
背景与目的：脯氨酰羟化酶（PHD）羟化缺氧诱导因子（HIF）α，导致HIF α降解。PHD家族包括PHD 1、PHD 2和PHD 3。PHDs的酶活性是O-2依赖性的，因此PHDs被认为是氧传感器以及肿瘤抑制剂。然而，PHDs在结直肠癌中的表达模式及其表达水平与肿瘤发生的相关性尚不清楚。方法：我们检测了60例原发性大肠癌组织中PHDs的表达，并与正常大肠组织配对。使用小干扰RNA（siRNA）敲低PHD 3表达水平;通过免疫印迹、免疫沉淀和组织化学分析来分析细胞。在nu/nu小鼠中分析体内肿瘤生长。结果：PHD 3在大肠癌组织中表达降低。PHD 3的表达降低与较高的肿瘤分级和转移相关。PHD 3抑制kappa B（I kappa B）激酶（IKK）β抑制剂的磷酸化和（NF）kappa B的活化，与其羟化酶活性无关。PHD 3与IKK β结合，但不靶向其破坏;相反，PHD 3阻断IKK β与IKK β磷酸化所需的Hsp 90之间的相互作用。PHD 3的敲除增加了结直肠癌细胞对肿瘤坏死因子-α和肿瘤发生的抵抗力。结论：PHD 3似乎是结肠直肠癌细胞中的肿瘤抑制因子，其抑制IKK β/NF-κ B信号传导，而不依赖于其羟化酶活性。在结肠癌中观察到NF-κ B的活化。PHD 3状态的测定有助于对NF-κ B活性增加的结直肠肿瘤患者进行靶向治疗选择。
BACKGROUND & AIMS: Prolyl hydroxylase (PHD) hydroxylates hypoxia inducible factor (HIF) alpha, leading to HIF alpha degradation. The PHD family comprises PHD1, PHD2, and PHD3. The enzymatic activity of PHDs is O-2-dependent, so PHDs are believed to be oxygen sensors as well as tumor suppressors. However, the expression pattern of PHDs in colorectal cancer and the correlation between their expression level and tumorigenesis is unclear. METHODS: We determined the expression of PHDs in 60 human primary colorectal carcinoma tissues, paired with normal colorectal tissues. PHD3 expression levels were knocked down using small interfering RNA (siRNA); cells were analyzed by immunoblotting, immunoprecipitation, and histochemical analyses. In vivo tumor growth was analyzed in nu/nu mice. RESULTS: Expression of PHD3 is decreased in colorectal cancer tissues. Decreased expression of PHD3 is associated with higher tumor grade and metastasis. PHD3 inhibits phosphorylation of inhibitor of kappa B (I kappa B) kinase (IKK) beta and activation of (NF) kappa B, independent of its hydroxylase activity. PHD3 associates with IKK beta but does not target it for destruction; instead, PHD3 blocks the interaction between IKK beta and Hsp90 that is required for phosphorylation of IKK beta. Knockdown of PHD3 increased resistance of colorectal cancer cells to the effects of tumor necrosis factor-alpha and tumorigenesis. CONCLUSIONS: PHD3 appears to be a tumor suppressor in colorectal cancer cells that inhibits IKK beta/NF-kappa B signaling, independent of its hydroxylase activity. Activation of NF-kappa B has been observed in colon cancer. Determination of PHD3 status could aid targeted therapy selection for patients with colorectal tumors that have increased NF-kappa B activity.