Abstract 5172: Deposition of platelets in sinusoids and its contribution to hepatocarcinogenesis

Platelets can activate hepatocyte proliferation not only via releasing the platelet factors, but also promoting for liver sinusoidal endothelial cells (LSEC) and Kupffer cells to produce the factors such as IL-6 and TGF-α that are indispensable for hepatocyte proliferation. We previously reported that in the transgenic (TG) mice with liver specific human BRAFV600E mutation, which corresponds to the mouse BrafV637E that is highly prevalent in mouse DEN-induced hepatic tumors, exhibit increased liver weight five times larger than that of normal mice. Furthermore, hepatocytes in these mice overexpress thrombopoietin (TPO) in association with megakaryocytosis/thrombocytosis, and large numbers of platelets were deposited in the liver sinusoids. In the present study, we investigated whether platelets are deposited in liver sinusoids in hepatic tumors in human and mice. CD61 immunohistochemical staining revealed the increased numbers of platelets were deposited in the sinusoids in foci, adenomas and hepatocellular carcinomas (HCC) induced by neonatal treatment with DEN compared to surrounding normal hepatic tissues. Moreover, increased numbers of platelets were deposited in sinusoids of dysplastic nodules and well-differentiated HCC compared to normal liver tissue and cirrhotic nodules in human. In addition, we evaluated the correlation between the tumor diameters and peripheral platelets numbers in the patients who were primarily diagnosed as HCC in our institute. The result indicated that the numbers of peripheral platelets are positively correlated with the tumor diameters. These results indicate that platelets contribute to development of HCC via interacting sinusoidal cells. Citation Format: Hiroki Tanaka, Kie Horioka, Masahiro Yamamoto, Koji Sawada, Takumu Hasebe, Kosuke Yamazaki, Katsuhiro Ogawa. Deposition of platelets in sinusoids and its contribution to hepatocarcinogenesis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 5172.