Reif S, Weis B, Aeed H, Gana-Weis M, Zaidel L, Avni Y, Romanelli R G, Pinzani M, Kloog Y, Bruck R
Department of Pediatric Gastroenterology, Tel-Aviv, Sourasky Medical Center, Israel.
J Hepatol. 1999 Dec;31(6):1053-61. doi: 10.1016/s0168-8278(99)80318-3.
BACKGROUND/AIMS: Protooncogenes may play an important role, not only in carcinogenesis, but also in the regulation of normal cellular proliferation and differentiation. Several studies have indicated increased expression of the Ras protooncogenes in the liver in animal models and in patients with liver cirrhosis. The aim of the present study was to examine whether a synthetic Ras antagonist, S-farnesylthiosalicylic acid (FTS), which specifically dislodges Ras from the membrane of Ras-transformed fibroblasts (EJ cells), can prevent experimentally-induced liver cirrhosis in rats.
Cirrhosis was induced in male Wistar rats by intraperitoneal administration of thioacetamide (200 mg/kg twice weekly for 12 weeks). The Ras antagonist, farnesylthiosalicylic acid (FTS, 5 mg/kg), was administered during the study period 3 times a week. Ras expression in the liver was determined by Western blot analysis with pan anti-Ras antibodies and by immunohistochemistry.
Rats treated with thioacetamide and the Ras antagonist, farnesylthiosalicylic acid (FTS), for 12 weeks had lower histopathologic scores of fibrosis and inflammation (p-values of 0.003 and 0.008, respectively) than those treated with thioacetamide only. There were no differences between the histopathologic scores in vehicle (control) and in Ras-antagonist (FTS) only treatments. Analysis of hepatic hydroxyproline levels from the two thioacetamide-treated groups and controls confirmed the histopathologic scores (7.7+/-0.9 mg/g protein in the TAA-treated vs. 3.8+/-0.5 mg/g protein in the TAA+FTS treated group, p = 0.007). Ras levels, determined by Western blot analysis, were markedly increased in the livers treated with TAA (17-fold over control) and significantly decreased (by about 70%) in the livers of rats treated with TAA and FTS. Studies in isolated human hepatic stellate cells demonstrated that FTS inhibited both DNA synthesis and migration of those cells (p<0.05).
These results indicate that inhibition of Ras expression in the liver during fibrogenesis, prevents the development of experimentally-induced hepatic cirrhosis.
背景/目的：原癌基因不仅可能在致癌过程中发挥重要作用，还可能在正常细胞增殖和分化的调节中起作用。多项研究表明，在动物模型和肝硬化患者的肝脏中，Ras原癌基因的表达增加。本研究的目的是检验一种合成的Ras拮抗剂，即S-法尼基硫代水杨酸（FTS），它能特异性地使Ras从Ras转化的成纤维细胞（EJ细胞）膜上脱离，是否能预防大鼠实验性诱导的肝硬化。
通过腹腔注射硫代乙酰胺（200mg/kg，每周两次，共12周）诱导雄性Wistar大鼠发生肝硬化。在研究期间，每周3次给予Ras拮抗剂法尼基硫代水杨酸（FTS，5mg/kg）。用泛抗Ras抗体通过蛋白质印迹分析和免疫组织化学法测定肝脏中的Ras表达。
用硫代乙酰胺和Ras拮抗剂法尼基硫代水杨酸（FTS）治疗12周的大鼠，其纤维化和炎症的组织病理学评分低于仅用硫代乙酰胺治疗的大鼠（纤维化的p值为0.003，炎症的p值为0.008）。仅用载体（对照）和仅用Ras拮抗剂（FTS）治疗的组织病理学评分之间没有差异。对两个硫代乙酰胺治疗组和对照组的肝脏羟脯氨酸水平分析证实了组织病理学评分（硫代乙酰胺治疗组为7.7±0.9mg/g蛋白质，硫代乙酰胺+FTS治疗组为3.8±0.5mg/g蛋白质，p = 0.007）。通过蛋白质印迹分析测定，硫代乙酰胺治疗的肝脏中Ras水平显著升高（比对照高17倍），而在硫代乙酰胺和FTS治疗的大鼠肝脏中显著降低（约70%）。在分离的人肝星状细胞中的研究表明，FTS抑制了这些细胞的DNA合成和迁移（p<0.05）。
这些结果表明，在纤维化形成过程中抑制肝脏中的Ras表达可预防实验性诱导的肝硬化的发展。
