Li Lin, Pan Xiang-Yang, Shu Jing, Jiang Rong, Zhou Yu-Jian, Chen Jun-Xia
Department of Cell Biology and Genetics, Chongqing Medical University, Chongqing 400016, PR China.
Laboratory of Stem Cells and Tissue Engineering, Chongqing Medical University, Chongqing 400016, PR China.
Biochimie. 2014 Aug;103:89-100. doi: 10.1016/j.biochi.2014.04.007. Epub 2014 Apr 24.
Human ribonuclease inhibitor (RI), a cytoplasmic protein, is constructed almost entirely of leucine rich repeats. RI could suppress activities of ribonuclease and angiogenin (ANG) through closely combining with them. ANG is a potent inducer of blood vessel growth and has been implicated in the establishment, growth, and metastasis of tumors. ILK/PI3K/AKT signaling pathway also plays important roles in cell growth, cell-cycle progression, tumor angiogenesis, and cell apoptosis. Our previous experiments demonstrated that RI might effectively inhibit some tumor growth and metastasis. Our recent study showed that ILK siRNA inhibited the growth and induced apoptosis in bladder cancer cells as well as increased RI expression, which suggest a correlation between RI and ILK. However, the exact molecular mechanism of RI in anti-tumor and in the cross-talk of ANG and ILK signaling pathway remains largely unknown. Here we investigated the effects of up-regulating RI on the growth and apoptosis in murine melanoma cells through angiogenin and ILK/PI3K/AKT signaling pathway. We demonstrated that up-regulating RI obviously decreased ANG expression and activity. We also discovered that RI overexpression could remarkably inhibit cell proliferation, regulate cell cycle and induce apoptosis. Furthermore, up-regulation of RI inhibited phosphorylation of ILK downstream signaling targets protein kinase B/Akt, glycogen synthase kinase 3-beta (GSK-3β), and reduced β-catenin expression in vivo and vitro. More importantly, RI significant inhibited the tumor growth and angiogenesis of tumor bearing C57BL/6 mice. In conclusion, our findings, for the first time, suggest that angiogenin and ILK signaling pathway plays a pivotal role in mediating the inhibitory effects of RI on melanoma cells growth. This study identifies that RI may be a useful molecular target for melanoma therapy.
人核糖核酸酶抑制剂（RI）是一种细胞质蛋白，几乎完全由富含亮氨酸的重复序列构成。RI可通过与核糖核酸酶和血管生成素（ANG）紧密结合来抑制它们的活性。ANG是血管生长的强效诱导剂，与肿瘤的发生、生长和转移有关。ILK/PI3K/AKT信号通路在细胞生长、细胞周期进程、肿瘤血管生成和细胞凋亡中也发挥着重要作用。我们之前的实验表明，RI可能有效抑制某些肿瘤的生长和转移。我们最近的研究表明，ILK siRNA可抑制膀胱癌细胞的生长并诱导其凋亡，同时增加RI的表达，这表明RI与ILK之间存在相关性。然而，RI在抗肿瘤以及ANG和ILK信号通路相互作用中的具体分子机制仍 largely未知。在此，我们通过血管生成素和ILK/PI3K/AKT信号通路研究了上调RI对小鼠黑色素瘤细胞生长和凋亡的影响。我们证明上调RI明显降低了ANG的表达和活性。我们还发现RI过表达可显著抑制细胞增殖、调节细胞周期并诱导凋亡。此外，上调RI在体内外均抑制了ILK下游信号靶点蛋白激酶B/Akt、糖原合酶激酶3-β（GSK-3β）的磷酸化，并降低了β-连环蛋白的表达。更重要的是，RI显著抑制了荷瘤C57BL/6小鼠的肿瘤生长和血管生成。总之，我们的研究结果首次表明血管生成素和ILK信号通路在介导RI对黑色素瘤细胞生长的抑制作用中起关键作用。本研究确定RI可能是黑色素瘤治疗的一个有用分子靶点。
