Lysophosphatidic acid-induced effects in human colon carcinoma DLD1 cells are partially dependent on transactivation of epidermal growth factor receptor
Lysophosphatidic acid-induced effects in human colon carcinoma DLD1 cells are partially dependent on transactivation of epidermal growth factor receptor
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DOI：
10.1016/j.jss.2005.07.040
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发表时间：
2006-05-01
影响因子：
2.2
通讯作者：
Nagawa, H
中科院分区：
文献类型：
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作者：
Mori, K;Kitayama, J;Nagawa, H
背景溶血磷脂酸（LPA）是一种对多种细胞有不同作用的脂质介质。众所周知，LPA在某些细胞类型中诱导表皮生长因子受体（EGFR）的磷酸化，这被称为反式激活。在这项研究中，我们研究了EGFR反式激活在LPA诱导的结肠癌DLD 1细胞反应中的作用。免疫沉淀法检测LPA是否诱导EGFR磷酸化。然后，我们研究了LPA诱导的DLD 1细胞迁移和IL-8分泌。在改良的Boyden室中测量迁移，并通过ELISA测量IL-8分泌。在这些实验中，我们使用EGFR抑制剂AG 1478或基质金属蛋白酶（MMP）抑制剂GM 6001。免疫沉淀分析显示，LPA诱导DLD 1细胞中EGFR的酪氨酸磷酸化的显着水平。AG 1478或GM 6001几乎完全消除了LPA诱导的EGFR磷酸化。LPA诱导DLD 1细胞迁移和IL-8分泌，AG 1478或GM 6001可显著抑制LPA诱导的DLD 1细胞迁移和IL-8分泌。然而，抑制作用仅为部分（迁移;分别为29% +/-2%、32 +/- 13%抑制，IL-8分泌;分别为33% +/-1%、26% +/- 5%抑制）。这些结果清楚地表明，LPA作用于EGFR的上游并补偿EGF信号，EGF信号的拮抗作用不能完全阻断结肠癌细胞中的肿瘤进展。阻断LPA信号可能在结肠癌的治疗中具有临床意义。(c)2005年爱思唯尔公司All rights reserved.
Background. Lysophosphatidic acid (LPA) is a lipid mediator of diverse effects on various cells. LPA is well known to induce phosphorylation of the epidermal growth factor receptor (EGFR), which is termed transactivation, in some cell types. In this study, we investigated the contribution of EGFR transactivation in LPA-induced responses in colon cancer DLD1 cells.Materials and methods. Immunoprecipitation was performed to investigate whether LPA induced EGFR phosphorylation. Then, we investigated LPA-induced migration and IL-8 secretion in DLD1 cells. Migration was measured in a modified Boyden chamber and IL-8 secretion was measured by ELISA. In these experiments we used an EGFR inhibitor, AG1478 or matrix metalloproteinase (MMP) inhibitor, GM6001.Results. Immunoprecipitation analysis revealed that LPA induced a significant level of tyrosine phosphorylation of EGFR in DLD1 cells. The LPA-induced phosphorylation of EGFR was almost completely abrogated by either AG1478 or GM6001. LPA induced significant migration and IL-8 secretion in DLD1, both of which were significantly inhibited by AG1478 or GM6001. However, the inhibitory effects were only partial (migration; 29% +/- 2%, 32 +/- 13% inhibition, IL-8 secretion; 33% +/- 1%, 26% +/- 5% inhibition, respectively).Conclusion. These results clearly indicate that LPA acts upstream of EGFR and compensates the EGF signal and antagonism of the EGF signal cannot completely block tumor progression in colon cancer cells. Blockade of the LPA signal may have clinical significance in the treatment of colon cancer. (c) 2005 Elsevier Inc. All rights reserved.