Roles of palmitoylation and the KIKK membrane-targeting motif in leukemogenesis by oncogenic KRAS4A.
Roles of palmitoylation and the KIKK membrane-targeting motif in leukemogenesis by oncogenic KRAS4A.
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棕榈酰化和 KIKK 膜靶向基序在致癌 KRAS4A 导致的白血病发生中的作用
DOI：
10.1186/s13045-015-0226-1
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发表时间：
2015-12-30
影响因子：
28.5
通讯作者：
Ren R
中科院分区：
文献类型：
--
作者：
Zhao H;Liu P;Zhang R;Wu M;Li D;Zhao X;Zhang C;Jiao B;Chen B;Chen Z;Ren R
我们之前已经表明棕榈酰化对NRAS白血病发生至关重要，这表明靶向RAS棕榈酰化可能是治疗NRAS相关癌症的有效方法。对于kras驱动的癌症，尽管很多研究都集中在KRAS4B剪接变体上，它不经历棕榈酰化，但KRAS4A最近被证明在致癌物诱导的小鼠肺癌的发展中发挥重要作用，并在人类癌症中广泛表达。然而，棕榈酰化在KRAS4A肿瘤发生中的作用尚不清楚。方法采用western blotting和RT-qPCR检测KRAS4A inkras突变的白血病细胞株和急性髓系白血病（AML）细胞的表达。通过小鼠骨髓转导和移植模型及体外转化实验检测致癌KRAS4A及其棕榈酰化缺陷突变体的致白血病潜能。分别通过western blot和共聚焦显微镜分析RAS下游信号通路的激活和KRAS4A及其突变体的膜定位。结果我们发现KRAS4A在人类白血病细胞系和携带KRAS4A突变的AML细胞中表达，并且致癌KRAS4A棕榈酰化位点的突变显著地消除了其致白血病潜能。然而，与NRAS不同，棕榈酰化缺陷KRAS4A在小鼠中仍然诱导白血病，尽管潜伏期更长。利用NRAS/KRAS4A嵌合结构，我们发现KRAS4A的KIKK基序有助于KRAS4A的转化活性。棕榈酰化位点和KIKK基序的突变会破坏致癌KRAS4A诱导小鼠白血病的能力。结论研究表明，靶向RAS棕榈酰化的治疗方法也可有效治疗KRAS4A相关恶性肿瘤，干扰KIKK膜靶向基序可提高治疗效果。
BackgroundWe have previously shown that palmitoylation is essential for NRAS leukemogenesis, suggesting that targeting RAS palmitoylation may be an effective therapy for NRAS-related cancers. For KRAS-driven cancer, although much research has been focused on the KRAS4B splice variant, which does not undergo palmitoylation, KRAS4A has recently been shown to play an essential role in the development of carcinogen-induced lung cancer in mice and to be widely expressed in human cancers. However, the role of palmitoylation in KRAS4A tumorigenesis is not clear.MethodsThe expression of KRAS4A inKRAS-mutated leukemia cell lines and acute myeloid leukemia (AML) cells were checked using western blotting and reverse transcriptions-quantitative polymerase chain reaction (RT-qPCR) analysis, respectively. The leukemogenic potentials of oncogenic KRAS4A and its palmitoylation-defective mutants were examined by a mouse bone marrow transduction and transplantation model and the in vitro transformation assays. The activation of the RAS downstream signaling pathways and the membrane localizations of the KRAS4A and its mutants were analyzed via western blot analysis and confocal microscopy, respectively.ResultsWe show here that KRAS4A is expressed in human leukemia cell lines and in AML cells harboringKRASmutations and that mutation at the palmitoylation site of oncogenic KRAS4A significantly abrogates its leukemogenic potential. However, unlike NRAS, palmitoylation-defective KRAS4A still induces leukemia in mice, albeit with a much longer latency. Using NRAS/KRAS4A chimeric constructs, we found that the KIKK motif of KRAS4A contributes to the transforming activity of KRAS4A. Mutations at both palmitoylation site and the KIKK motif abolish the ability of oncogenic KRAS4A to induce leukemia in mice.ConclusionsOur studies suggest that therapies targeting RAS palmitoylation may also be effective in treating KRAS4A associated malignancies and that interfering the KIKK membrane-targeting motif would enhance the therapeutic effectiveness.