Cancer Science. 2008 Aug;99(8):1603-10. [Link]
Yamada T, Yano S, Ogino H, Ikuta K, Kakiuchi S, Hanibuchi M, Kanematsu T, Taniguchi T, Sekido Y, Sone S.
Department of Internal Medicine and Molecular Therapeutics, Institute of Health Biosciences, University of Tokushima Graduate School, 3-18-15 Kuramoto-cho, Tokushima 770-8503, Japan.
Lysophosphatidic acid (LPA) is one of the simplest natural phospholipids. This phospholipid is recognized as an extracellular potent lipid mediator with diverse effects on various cells. Although LPA is shown to stimulate proliferation and motility via LPA receptors, LPA1 and LPA2, in several cancer cell lines, the role of LPA and LPA receptors for malignant pleural mesothelioma (MPM) has been unknown. MPM is an aggressive malignancy with a poor prognosis and the incidence is increasing and is expected to increase further for another 10–20 years worldwide. Therefore, the development of novel effective therapies is needed urgently. In this study, we investigated the effect of LPA on the proliferation and motility of MPM cells. We found that all 12 cell lines and four clinical samples of MPM expressed LPA1, and some of them expressed LPA2, LPA3, LPA4 and LPA5. LPA stimulated the proliferation and motility of MPM cells in a dose-dependent manner. Moreover, LPA-induced proliferation was inhibited by Ki16425, an inhibitor of LPA1, and small interfering RNA against LPA1, but not LPA2. Interestingly, LPA-induced motility was inhibited by small interfering RNA against LPA2, but not LPA1, unlike a number of previous reports. These results indicate that LPA is a critical factor on proliferation though LPA1, and on motility though LPA2 in MPM cells. Therefore, LPA and LPA receptors, LPA2 as well as LPA1, represent potential therapeutic targets for patients with MPM.