Abstract 1046: Statin inhibits malignant mesothelioma cell growth by inactivating YAP1

Abstract

Abstract The prognosis of patients with malignant mesothelioma (MM) remains very poor because of highly invasive tumor characteristics and therapeutic resistance of this tumor. Recent studies have shown that MM frequently shows Hippo signaling pathway inactivation, which leads to activation of YAP1 transcriptional co-activator. Although substantial data from clinical trials and epidemiological studies showed promising results for the use of statins in many cancers, few studies have argued about the underlying tumor-suppressive mechanisms of statins. Here, we show that statins act as an inhibitor of YAP1-dependent MM cell growth via mevalonate pathway. In cell culture, statins attenuate migration and invasion of H290 malignant mesothelioma cells with homozygous deletion of NF2, which encodes Merlin, an upstream regulator of Hippo pathway. In contrast, geranylgeranyl diphosphate (GGPP), a down-stream activator of mevalonate pathway, completely rescues H290 cell growth inhibition by statins. We also found that statins accelerate YAP phosphorylation/inactivation, which results in the downregulation of Hippo-pathway targeting gene transcriptions including CTGF, CYR-61 and ANKRD1. Moreover, among 11 MM cell lines, we demonstrated that five out of the six cell lines, which showed significant cell growth inhibition with statins, harbor NF2 and/or LATS2 mutations. Finally, we found that phospho-YAP/YAP ratio was increased in statin-sensitive cells, but not in statin-resistant cells. Together, our findings suggest that mevalonate pathway plays crucial roles in YAP-dependent MM cells by Hippo pathway inactivation, and therefore represents a potential therapeutic target for MM. Citation Format: Kosuke Tanaka, Taketo Kato, Akihiro Matsushita, Hiromi Furuta, Yuko Murakami, Hirotaka Osada, Yoshitaka Sekido. Statin inhibits malignant mesothelioma cell growth by inactivating YAP1. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1046.