Zhou Jun-min, Pan Qi-chao, Yang Xiao-ping, Liu Zong-chao, Liao Duan-fang, Fu Li-wu, Liang Yong-ju
Cancer Institute, Sun Yat-sen University, Guangzhou 510060, P. R. China.
Ai Zheng. 2002 Apr;21(4):364-8.
Treatment with anti-cancer agents has failed to achieve satisfactory results in hepatocellular carcinoma. In the process of hepatocarcinogenesis, Ras has been shown to play an important role. Ras requires a farnesyl moiety for activation. It has been found that farnesyltransferase inhibitor Manumycin inhibits farnesyl protein transferase, which catalyzes farnesylation. This study was designed to investigate the antitumor effect of Manumycin in human hepatoma cell line HepG2 and try to clarify its influence on Ras pathway.
The growth inhibitory effect of farnesyltransferase inhibitor Manumycin on human hepatoma cell line HepG2 was observed by using [3H]thymidine incorporation assay. The relative protein expressions of pan-Ras, N-Ras, ERK1/2, AKT, and MKP-1 affected by Manumycin were determined by using Western blot analysis.
Manumycin(5, 10, 20, 40, and 80 mumol/L) significantly inhibited cell growth of human hepatoma cell line HepG2 with IC50 value of (17.1 +/- 2.6) mumol/L. Manumycin could inhibit both pan-Ras and N-Ras in human hepatoma HepG2 cells, but its inhibitory effect on pan-Ras of cell membrane was much stronger. Phospho-MAPK and phospho-AKT decreased significantly after treatment of HepG2 cells with Manumycin, while total MAPK and AKT were hardly affected. After treatment with 10 nmol/L wortmannin for 1 h, which had potent inhibitory effect on phosphorylation of AKT, Manumycin had stronger inhibitory effect on phosphorylation of AKT as compared to treatment without wortmannin, eventhough AKT protein levels were still unaffected. Furthermore, the expression of MKP-1 was elevated through manumycin treatment in a concentration-dependent manner.
Manumycin may significantly inhibit the growth of human hepatoma cell line HepG2, which was related to its inhibition on the combination of Ras and cell membrane and increasing the expression of MKP-1, accordingly inhibiting activation of ERK1/2 and AKT. These results suggest that Manumycin antagonizes the growth of HepG2 via the suppression of ras farnesylation blocking the function of oncogenic ras against and could be a potential new anti-cancer agents human cancer, including hepatocellular carcinoma.
抗癌药物治疗在肝细胞癌中未能取得满意疗效。在肝癌发生过程中，Ras已被证明发挥重要作用。Ras激活需要法尼基部分。已发现法尼基转移酶抑制剂马尼霉素可抑制催化法尼基化的法尼基蛋白转移酶。本研究旨在探讨马尼霉素对人肝癌细胞系HepG2的抗肿瘤作用，并试图阐明其对Ras信号通路的影响。
采用[3H]胸腺嘧啶掺入法观察法尼基转移酶抑制剂马尼霉素对人肝癌细胞系HepG2的生长抑制作用。采用蛋白质印迹分析测定马尼霉素作用后泛Ras、N-Ras、ERK1/2、AKT和MKP-1的相对蛋白表达。
马尼霉素（5、10、20、40和80μmol/L）显著抑制人肝癌细胞系HepG2的细胞生长，IC50值为（17.1±2.6）μmol/L。马尼霉素可抑制人肝癌HepG2细胞中的泛Ras和N-Ras，但其对细胞膜泛Ras的抑制作用更强。用马尼霉素处理HepG2细胞后，磷酸化MAPK和磷酸化AKT显著降低，而总MAPK和AKT几乎不受影响。在用10 nmol/L渥曼青霉素处理1小时后，渥曼青霉素对AKT磷酸化有强效抑制作用，与未用渥曼青霉素处理相比，马尼霉素对AKT磷酸化的抑制作用更强，尽管AKT蛋白水平仍未受影响。此外，通过马尼霉素处理，MKP-1的表达呈浓度依赖性升高。
马尼霉素可能显著抑制人肝癌细胞系HepG2的生长，这与其抑制Ras与细胞膜的结合及增加MKP-1的表达有关，从而抑制ERK1/2和AKT的激活。这些结果表明，马尼霉素通过抑制Ras法尼基化拮抗HepG2的生长，阻断致癌性Ras的功能，可能成为包括肝细胞癌在内的人类癌症的潜在新型抗癌药物。
