Constitutive activation of the Ras-Raf signaling pathway in metastatic melanoma is associated with poor prognosis.
Constitutive activation of the Ras-Raf signaling pathway in metastatic melanoma is associated with poor prognosis.
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DOI：
10.1186/1477-3163-3-6
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发表时间：
2004
影响因子：
--
通讯作者：
Rapp UR
中科院分区：
文献类型：
--
作者：
Houben R;Becker JC;Kappel A;Terheyden P;Bröcker EB;Goetz R;Rapp UR
Raf家族的基因编码由Ras调节并介导对生长信号的细胞应答的激酶。最近，研究表明BRaf的激活突变在人类黑色素瘤中的频率很高。在黑素瘤中最常突变的Ras家族成员是NRas。Ras/Raf信号通路的组成性激活表明对肿瘤的临床过程的影响。为了解决这个问题，我们分析了114个原发性皮肤黑色素瘤和86个转移性病变的肿瘤DNA，从174例患者中获得的突变BRaf（外显子15和11）和NRas（外显子1和2）的PCR产物的直接测序，并将这些结果与临床过程。在57.5%的肿瘤中，BRaf或NRas突变，转移性病变的发生率（66.3%）高于原发性病变（50.9%）。尽管大多数BRaf突变影响密码子599，但在该位置几乎15%的突变与充分描述的从缬氨酸到谷氨酸的交换不同。这些突变（V599 R和V599 K）也显示出增加的激酶和转化活性。令人惊讶的是，另外的BRaf变体D593 V、G465 R和G465 E在体外激酶测定中显示出活性完全丧失;然而，过表达这些突变体的细胞显示出增加的Erk磷酸化。突变状态与临床病程的相关性表明，原发性肿瘤中BRaf/NRas突变的存在对无进展生存期或总生存期没有负面影响。然而，相比之下，对于转移性病变，BRAF/NRAS突变的存在与显著较差的预后相关，即生存期缩短。在迄今为止报道的最大系列的直接分析肿瘤中，我们证明了黑色素瘤中激活BRaf突变的高频率-尽管低于最初的预期。值得注意的是，转移性黑色素瘤中携带激活BRaf突变的患者的临床过程受到这些患者中存在组成性BRaf激活的显著影响。
Genes of the Raf family encode kinases that are regulated by Ras and mediate cellular responses to growth signals. Recently, it was shown that activating mutations of BRaf are found with high frequency in human melanomas. The Ras family member most often mutated in melanoma is NRas. The constitutive activation of the Ras/Raf signaling pathway suggests an impact on the clinical course of the tumor. To address this notion, we analyzed tumor DNA from 114 primary cutaneous melanomas and of 86 metastatic lesions obtained from 174 patients for mutations in BRaf (exons 15 and 11) and NRas (exons 1 and 2) by direct sequencing of PCR products and correlated these results with the clinical course. In 57.5% of the tumors either BRaf or NRas were mutated with a higher incidence in metastatic (66.3%) than in primary lesions (50.9%). Although the majority of BRaf mutations affected codon 599, almost 15% of mutations at this position were different from the well-described exchange from valine to glutamic acid. These mutations (V599R and V599K) also displayed increased kinase and transforming activity. Surprisingly, the additional BRaf variants D593V, G465R and G465E showed a complete loss of activity in the in vitro kinase assay; however, cells overexpressing these mutants displayed increased Erk phosphorylation. The correlation of mutational status and clinical course revealed that the presence of BRaf/NRas mutations in primary tumors did not negatively impact progression free or overall survival. In contrast, however, for metastatic lesions the presence of BRAF/NRAS mutations was associated with a significantly poorer prognosis, i.e. a shortened survival. We demonstrate a high – albeit lower than initially anticipated – frequency of activating BRaf mutations in melanoma in the largest series of directly analyzed tumors reported to date. Notably, the clinical course of patients harboring activating BRaf mutations in metastatic melanoma was significantly affected by the presence of a constitutive BRaf activation in these.