Newell Pippa, Toffanin Sara, Villanueva Augusto, Chiang Derek Y, Minguez Beatriz, Cabellos Laia, Savic Radoslav, Hoshida Yujin, Lim Kiat Hon, Melgar-Lesmes Pedro, Yea Steven, Peix Judit, Deniz Kemal, Fiel M Isabel, Thung Swan, Alsinet Clara, Tovar Victoria, Mazzaferro Vincenzo, Bruix Jordi, Roayaie Sasan, Schwartz Myron, Friedman Scott L, Llovet Josep M
Mount Sinai Liver Cancer Program, Mount Sinai School of Medicine, 1425 Madison Avenue, New York, NY 10029, USA.
J Hepatol. 2009 Oct;51(4):725-33. doi: 10.1016/j.jhep.2009.03.028. Epub 2009 Jun 12.
BACKGROUND/AIMS: The success of sorafenib in the treatment of advanced hepatocellular carcinoma (HCC) has focused interest on the role of Ras signaling in this malignancy. We investigated the molecular alterations of the Ras pathway in HCC and the antineoplastic effects of sorafenib in combination with rapamycin, an inhibitor of mTOR pathway, in experimental models.
Gene expression (qRT-PCR, oligonucleotide microarray), DNA copy number changes (SNP-array), methylation of tumor suppressor genes (methylation-specific PCR) and protein activation (immunohistochemistry) were analysed in 351 samples. Anti-tumoral effects of combined therapy targeting the Ras and mTOR pathways were evaluated in cell lines and HCC xenografts.
Different mechanisms accounted for Ras pathway activation in HCC. H-ras was up-regulated during different steps of hepatocarcinogenesis. B-raf was overexpressed in advanced tumors and its expression was associated with genomic amplification. Partial methylation of RASSF1A and NORE1A was detected in 89% and 44% of tumors respectively, and complete methylation was found in 11 and 4% of HCCs. Activation of the pathway (pERK immunostaining) was identified in 10.3% of HCC. Blockade of Ras and mTOR pathways with sorafenib and rapamycin reduced cell proliferation and induced apoptosis in cell lines. In vivo, the combination of both compounds enhanced tumor necrosis and ulceration when compared with sorafenib alone.
Ras activation results from several molecular alterations, such as methylation of tumor suppressors and amplification of oncogenes (B-raf). Sorafenib blocks signaling and synergizes with rapamycin in vivo, preventing tumor progression. These data provide the rationale for testing this combination in clinical studies.
背景/目的：索拉非尼在晚期肝细胞癌（HCC）治疗中取得的成功引发了人们对Ras信号通路在这种恶性肿瘤中作用的关注。我们在实验模型中研究了HCC中Ras通路的分子改变以及索拉非尼与mTOR通路抑制剂雷帕霉素联合使用的抗肿瘤作用。
对351份样本进行基因表达（qRT-PCR、寡核苷酸微阵列）、DNA拷贝数变化（SNP阵列）、肿瘤抑制基因甲基化（甲基化特异性PCR）和蛋白激活（免疫组织化学）分析。在细胞系和HCC异种移植模型中评估靶向Ras和mTOR通路的联合治疗的抗肿瘤效果。
HCC中Ras通路激活存在不同机制。H-ras在肝癌发生的不同阶段上调。B-raf在晚期肿瘤中过度表达，其表达与基因组扩增相关。分别在89%和44%的肿瘤中检测到RASSF1A和NORE1A的部分甲基化，在11%和4%的HCC中发现完全甲基化。在10.3%的HCC中鉴定出该通路的激活（pERK免疫染色）。索拉非尼和雷帕霉素阻断Ras和mTOR通路可减少细胞系中的细胞增殖并诱导凋亡。在体内，与单独使用索拉非尼相比，两种化合物联合使用可增强肿瘤坏死和溃疡。
Ras激活源于多种分子改变，如肿瘤抑制基因甲基化和癌基因（B-raf）扩增。索拉非尼阻断信号传导并在体内与雷帕霉素协同作用，防止肿瘤进展。这些数据为在临床研究中测试这种联合用药提供了理论依据。
