Efficacy of the farnesyltransferase inhibitor R115777 in a rat mammary tumor model: role of Ha-ras mutations and use of microarray analysis in identifying potential targets.
Efficacy of the farnesyltransferase inhibitor R115777 in a rat mammary tumor model: role of Ha-ras mutations and use of microarray analysis in identifying potential targets.
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法尼基转移酶抑制剂 R115777 在大鼠乳腺肿瘤模型中的功效：Ha-ras 突变的作用以及使用微阵列分析识别潜在靶点。
DOI：
10.1093/carcin/bgi341
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发表时间：
2006
期刊：
影响因子：
4.7
通讯作者：
You,Ming
中科院分区：
文献类型：
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作者：
Yao,Ruisheng;Wang,Yian;Lu,Yan;Lemon,WilliamJ;End,DavidW;Grubbs,ClintonJ;Lubet,RonaldA;You,Ming
用烷基化剂甲基亚硝基脲（MNU）治疗的大鼠发生多种激素依赖性乳腺肿瘤。大约50%的肿瘤有Ha-ras突变，而50%没有。采用mnu诱导的大鼠乳腺肿瘤模型，检测法尼基转移酶抑制剂（FTI） R115777的治疗效果，并研究基因组学在鉴定易感肿瘤和FTI治疗调节表达基因中的应用。对于可触及乳腺肿瘤（直径<7 mm）的动物，我们进行了手术活检，活检后3天，大鼠灌胃R115777 （50 mg/kg体重量/天）。Ha-ras突变的肿瘤消退明显，近90%的肿瘤在4周内完全消退。相比之下，非ha -ras突变肿瘤产生了更多的可变反应，尽管大约一半的非ha -ras突变肿瘤出现了显著的消退。这些结果表明，尽管所有肿瘤似乎对FTI抑制剂有反应，但Ha-ras突变的肿瘤非常敏感。我们采用微阵列方法确定了R115777在FTI治疗后Ha-ras突变或野生型肿瘤中的潜在靶点和作用机制。此外，我们确定了FTI治疗前的基因表达是否可以用于区分高敏感性肿瘤（Ha-ras突变型）和可变敏感性肿瘤（Ha-ras野生型）。使用寡核苷酸阵列检测未治疗或fti治疗（50 mg/kg体重量4天）的肿瘤（Ha-ras突变型或野生型）。在Ha-ras突变激活或未激活的对照大鼠乳腺肿瘤中，大量基因存在差异表达，这表明微阵列分析可以区分高敏感和变敏感肿瘤。在肿瘤中被FTI调节表达的大多数基因与Ha-ras状态无关，可能是通过对Ha-ras以外的蛋白的法尼化作用来调节的。然而，用R155777治疗ha -ras-突变的乳腺肿瘤会优先调节ras-MAP激酶信号转导通路相关基因，并降低许多与细胞增殖相关基因的表达。相反，在没有Ha-ras突变的大鼠乳腺肿瘤中，几类基因发生了改变，这表明非ras靶点也参与其中。Ras通路相关基因p53、WT1和PCNA在Ha-ras突变的肿瘤中被优先调节，而g蛋白通路基因、各种细胞色素p450和RB1在Ha-ras野生型肿瘤中参与调节。阐明FTI治疗或对照大鼠乳腺腺癌的基因表达变化将有助于确定FTI治疗的潜在药效学标志物以及R115777和其他FTI的潜在分子靶点。
Rats treated with the alkylating agent methylnitrosourea (MNU) develop multiple, hormonally dependent mammary tumors. Roughly 50% of the tumors have Ha-ras mutation, whereas 50% do not. The MNU-induced rat mammary tumor model was employed to examine the therapeutic efficacy of the farnesyltransferase inhibitor (FTI), R115777, and to examine the use of genomics in identifying susceptible tumors as well as identifying genes whose expression are modulated by FTI treatment. In animals bearing palpable mammary tumors (<7 mm diameter), we performed a surgical biopsy, and 3 days following the biopsy, rats were treated with R115777 (50 mg/kg body wt/day) by gavage. Tumors with Ha-ras mutations underwent profound regression, with nearly 90% showing complete regressions within 4 weeks. In contrast, the non-Ha-ras mutation-bearing tumors yielded a more variable response, although roughly half of the non-Ha-ras mutation tumors underwent significant regression. These results show that although all tumors appear to respond to the FTI inhibitor the tumors with Ha-ras mutations were exquisitely sensitive. We employed a microarray approach to define potential targets and the mechanism of action of R115777 in Ha-ras mutant or wildtype tumors following treatment with FTI. In addition, we determined whether gene expression prior to FTI treatment can be used to differentiate highly sensitive tumors (Ha-ras mutant) and tumors with variable sensitivity (Ha-ras wildtype). Untreated or FTI-treated (4 days at 50 mg/kg body wt) tumors (Ha-ras mutant or wildtype) were examined using oligonucleotide arrays. A significant number of genes were differentially expressed in control rat mammary tumors with or without an activated Ha-ras mutation, suggesting that a microarray analysis might differentiate highly sensitive and variably sensitive tumors. Most of the genes whose expressions were modulated by FTI in tumors were independent of Ha-ras status and were presumably modulated by effects on farnesylation of proteins other than Ha-ras. However, treatment of Ha-ras-mutated mammary tumors with R155777 results in preferential modulation of genes involved in ras-MAP kinase signal transduction pathway and in decreased expression of many genes involved with cell proliferation. In contrast, several classes of genes are altered in rat mammary tumors without a mutated Ha-ras, suggesting that non-ras targets are involved. Ras pathway related genes, p53, WT1 and PCNA, were preferentially modulated in Ha-ras-mutated tumors, whereas modulation of genes in the G-protein pathway, various cytochrome p450s and RB1 are involved in Ha-ras wildtype tumors. Elucidation of gene expression changes in FTI-treated or control rat mammary adenocarcinomas will help in identifying potential pharmacodynamic markers of FTI treatment as well as potential molecular targets of R115777 and other FTIs.