Analysis of PI3K signal transduction and target therapy of PI3Kp85 by PR-39 analog for hepatocellular carcinoma

PR-39是一种哺乳动物内源性抗生素，作为天然免疫的效应分子，诱导Syndecan-1的合成，Syndecan-1是一种参与细胞-基质相互作用和皮肤伤口愈合的跨膜型硫酸肝素蛋白多糖。在此之前，我们发现Syndecan-1在高转移潜能的人肝细胞癌中的表达降低(MatSumoto，Int J Cancer，1997)。Syndecan-1基因转导抑制肝癌细胞株的侵袭活性。此外，作为syndecan-1的诱导剂的PR-39的基因转导，除了作用结构的解离外，还抑制了细胞的侵袭活性和运动活性(Ohtake，BR J Cancer，1999)。PR-39具有5个重复的富含脯氨酸的基序；PXXPPXXP具有与Src同源3(SH3)结构域结合的能力。PR-39实际上与p47；lt；Phox&gt；和p130；；cas&gt；的SH3结构域结合。确定PR-39在细胞内信号转导通路中的靶分子…此外，我们还将PR-39基因导入已活化的k-ras转化的成纤维细胞中。PR-39基因转染体显示肌动蛋白结构重组，细胞增殖受抑，丝裂原活化蛋白(MAP)激酶活性降低，PR-39与PI3-Kp85α结合，PI3-Kp85是PI3-Kp85的调节亚基，是ras诱导细胞骨架改变和刺激有丝分裂的效应器之一。因此，我们的研究结果表明，PR-39通过与PI3-Kinase P85α结合而改变肌动蛋白结构和细胞增殖(田中，Jpn J Cancer Res，2001)。此外，我们利用小鼠皮下移植肿瘤模型，研究了PR-39对小鼠结肠癌细胞株Colo26的抗癌作用。无论是PR-39合成肽的小鼠还是皮下移植的PR-39转基因小鼠，对肿瘤的生长都没有抑制作用。或者不是在皮下移植了携带PR-39的Colol26的小鼠身上。然而，与对照组相比，只有携带PR-39基因的小鼠的生存期延长。我们的数据提示，PR-39基因转导可能改善恶病质，延长生存期。较少

PR-39 is a mammalian endogenous antibiotic, which works as the effecter molecule of innate immunity, induces the synthesis of syndecan-1, a transmembrane heparin sulphate proteoglycan involved in cell-to matrix interactions and skin wound healing. Previously we revealed that the expression of syndecan-1 was reduced in human hepatocellular carcinomas with high metastatic potential (Matsumoto, Int J Cancer,1997). Gene transduction of syndecan-1 inhibits the invasion activity in hepatoma cell lines. Furthermore gene transduction of PR-39, which is inducer for syndecan-1, inhibits the invasion activity and suppresses the motile activity in addition to the disorganization of action structure (Ohtake, Br J Cancer,1999).PR-39 has five repeats of the praline-rich motif ; PXXPPXXP, which has an ability to bind to Src homology 3 (SH3) domains. PR-39 actually binds to SH3 domains of p47^<phox> and p130^<Cas>. To determine the target molecule of PR-39 in intracellular signal transduction pathway, … More we transfected PR-39 gene into the fibroblasts which had already been transformed with activated k-ras. The PR-39 gene transfectant showed reorganization of actin structure, suppression of cell proliferation and decrease of mitogen-activated protein (MAP) kinase activity PR-39 binds to PI3-kinase p85α, which is a regulatory subunit of PI3-kinase and one of the effectors by which ras induces cytoskeletal changes and stimulates mitogenesis. So our data suggest that PR-39 alters actin structure and cell proliferation by binding to PI3-kinase p85α (Tanaka, Jpn J Cancer Res,2001).Furthermore, we investigated with anti-cancer effect of PR-39 against mouse colon cancer cell line, colo26, which revealed cachexia using the mouse model of subcutaneous tumor transplantation. There was no effect for suppression of tumor growth in both the mice which have intra-pentoneal load of synthetic peptide of PR-39, and PR-39 transgenic mice, which were subcutaneously transplanted with colo26. Either not in the mice which were subcutaneously transplanted with colo26, which had been transfected with PR-39. However, the survival period of only the mice which carried PR-39 transfectants extended as compared with the control. Our data suggest that PR-39 gene transduction may improve cachexia and extend survival period. Less