Downregulation of Src-family tyrosine kinases by Srcasm and c-Cbl: A comparative analysis.
Downregulation of Src-family tyrosine kinases by Srcasm and c-Cbl: A comparative analysis.
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DOI：
10.4103/jcar.jcar_13_21
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发表时间：
2021
影响因子：
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通讯作者：
Seykora JT
中科院分区：
文献类型：
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作者：
Lee V;Griffin TD;Suzuki-Horiuchi Y;Wushanley L;Kweon Y;Marshall C;Li W;Ayli E;Haimovic A;Hines A;Seykora JT
Src家族酪氨酸激酶（SFK）活性升高驱动体内致癌作用，并且SFK活性升高普遍存在于人类癌症中。尽管人类鳞状细胞癌（SCC）表现出增加的SFK活性，但SCC的计算机模拟分析表明，只有0.4%的病变含有可能增加SFK活性的突变;类似地，在其他主要癌症中发现低频率的激活SFK突变。这些发现表明，癌症中的SFK激活可能不是由于激活突变，而是由于替代机制。为了评估潜在的替代机制，我们评估了c-Cbl和Srcasm在下调天然和活化突变形式的SFKs中的选择性。我们将天然和活化形式的Src和Fyn与c-Cbl和Srcasm共转染到HaCaT细胞中，并通过蛋白质印迹法监测Srcasm和c-Cbl下调天然和活化形式的SFKs的能力。使用Srcasm和c-Cbl的突变形式以及使用蛋白体和溶酶体抑制来探索下调的机制。数据表明Srcasm比c-Cbl更有效地下调天然Fyn和Src，而c-Cbl比Srcasm更有效地优先下调活化的SFK突变体，包括Fyn Y 528 F。Srcasm通过溶酶体依赖性机制下调SFKs，而c-Cbl利用蛋白酶体依赖性机制。鉴于人类癌症中激活SFK突变的罕见性，这些数据表明降低Srcasm水平/功能可能代表SCC和其他人类肿瘤中增加SFK活性的机制。
Elevated Src-Family tyrosine kinase (SFK) activity drives carcinogenesis in vivo and elevated SFK activity is found ubiquitously in human cancers. Although human squamous cell carcinomas (SCCs) demonstrate increased SFK activity, in silico analysis of SCCs demonstrates that only 0.4% of lesions contain mutations that could potentially increase SFK activity; similarly, a low frequency of activating SFK mutations is found in other major cancers. These findings indicate that SFK activation in cancers likely is not due to activating mutations but alternative mechanisms. To evaluate potential alternative mechanisms, we evaluated the selectivity of c-Cbl and Srcasm in downregulating native and activated mutant forms of SFKs. We co-transfected native and activated forms of Src and Fyn with c-Cbl and Srcasm into HaCaT cells and monitored the ability of Srcasm and c-Cbl to downregulate native and activated forms of SFKs by Western blotting. The mechanism of downregulation was probed using mutant forms of Srcasm and c-Cbl and using proteosomal and lysosomal inhibition. The data indicate that Srcasm downregulates native Fyn and Src more effectively than c-Cbl, whereas c-Cbl preferentially downregulates activated SFK mutants, including Fyn Y528F, more effectively than Srcasm. Srcasm downregulates SFKs through a lysosomal-dependent mechanism while c-Cbl utilizes a proteosomal-dependent mechanism. Given the rarity of activating SFK mutations in human cancer, these data indicate that decreasing Srcasm level/function may represent a mechanism for increasing SFK activity in SCC and other human tumors.