The bioactive phospholipids, lysophosphatidic acid (LPA) and phosphatidic acid (PA), regulate pivotal processes related to the pathogenesis of cancer. Here, we report characterization of a novel lipid kinase, designated acylglycerol kinase (AGK), that phosphorylates monoacylglycerol and diacylglycerol to form LPA and PA, respectively. Confocal microscopy and subcellular fractionation suggest that AGK is localized to the mitochondria. AGK expression was up-regulated in prostate cancers compared with normal prostate tissues from the same patient. Expression of AGK in PC-3 prostate cancer cells markedly increased formation and secretion of LPA. This increase resulted in concomitant transactivation of the EGF receptor and sustained activation of extracellular signal related kinase (ERK) 1/2, culminating in enhanced cell proliferation. AGK expression also increased migratory responses. Conversely, down-regulating expression of endogenous AGK inhibited EGF- but not LPA-induced ERK1/2 activation and progression through the S phase of the cell cycle. Hence, AGK can amplify EGF signaling pathways and may play an important role in the pathophysiology of prostate cancer.
生物活性磷脂,溶血磷脂酸(LPA)和磷脂酸(PA),调节与癌症发病相关的关键过程。在这里,我们报告了一个新型脂肪激酶的特性,称为酰基甘油激酶(AGK),它磷酸化单酰基甘油和二酰基甘油形成LPA和PA。共聚焦显微镜和亚细胞分离表明AGK定位于线粒体。与同一患者的正常前列腺组织相比,AGK表达在前列腺癌中上调。在PC-3前列腺癌细胞中表达AGK显著增加了LPA的形成和分泌。这种增加导致EGF受体的同时转录活化和细胞外信号相关激酶(ERK)1/2持续活化,最终增强了细胞增殖。AGK表达也增加了细胞的迁移反应。相反,下调内源性AGK的表达抑制了EGF诱导的ERK1/2活化和细胞周期S期的进展,但不影响LPA诱导的作用。因此,AGK可以放大EGF信号通路,并可能在前列腺癌的病理生理学中发挥重要作用。