Purpose

Upregulation of receptor tyrosine kinase EphA2 has been found to be associated with a poor prognosis in many types of cancer and is considered an attractive therapeutic target. As yet, few efforts have been focused on its tumor suppressive activity triggered by its ligand, ephrinA1. Here, we aimed to determine the potential of ephrinA1 as an important player in melanoma metastasis.

Methods

Data from the Cancer Genome Atlas (TCGA) and the Cancer Cell Line Encyclopedia (CCLE) were analyzed to explore the expression and prognostic implications of EphA2 and ephrinA1 in melanoma. Western blotting, shRNA, colony formation and immunofluorescence assays, as well as two in vivo xenograft models (subcutaneous and metastatic) were used to evaluate the role of EphA2 in melanoma progression. Akt inhibition and ephrinA1-Fc were used to confirm the influence of Akt activation and ephrinA1 levels on the EphA2 effects. Immunohistochemistry (IHC) was performed on xenograft and patient melanoma tissues.

Results

We found that high levels of ephrinA1, but not EphA2, were negatively correlated with melanoma metastasis. The expression levels of EphA2 and ephrinA1 were not correlated. After EphA2 downregulation, colony forming abilities and lung metastatic growth were reduced in melanoma cell lines with a low ephrinA1 expression, but were increased in melanoma cell lines with a high ephrinA1 expression. EphA2-mediated colony formation in EphA2-high/ephrinA1-low cells was found to be Akt-dependent and to be inhibited by the addition of ephrinA1-Fc. IHC staining of primary melanoma specimens revealed that EphA2-high/ephrinA1-low patients exhibited poorer outcomes than EphA2-high/ephrinA1-high patients.

Conclusions

From our data we conclude that evaluation of ephrinA1 levels may be helpful for the application of EphA2-targeted therapies and for prognostic predictions in melanoma patients.

中文翻译：

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EphA2敲低对黑色素瘤转移的影响取决于内在的ephrinA1水平。

目的

已经发现受体酪氨酸激酶EphA2的上调与许多类型的癌症的不良预后有关，并且被认为是有吸引力的治疗靶标。迄今为止，很少有研究集中在其配体ephrinA1触发的肿瘤抑制活性上。在这里，我们旨在确定ephrinA1作为黑色素瘤转移的重要参与者的潜力。

方法

分析了来自癌症基因组图谱（TCGA）和癌细胞系百科全书（CCLE）的数据，以探讨EphA2和ephrinA1在黑色素瘤中的表达及其对预后的影响。Western印迹，shRNA，集落形成和免疫荧光测定以及两个体内异种移植模型（皮下和转移性）用于评估EphA2在黑色素瘤进展中的作用。使用Akt抑制作用和ephrinA1-Fc来确认Akt激活和ephrinA1水平对EphA2效应的影响。在异种移植物和患者黑色素瘤组织上进行了免疫组织化学（IHC）。

结果

我们发现，高水平的ephrinA1，而不是EphA2，与黑色素瘤转移呈负相关。EphA2和ephrinA1的表达水平无关。EphA2下调后，在ephrinA1表达低的黑色素瘤细胞系中，集落形成能力和肺转移生长减少，而在ephrinA1表达高的黑色素瘤细胞系中集落形成能力和肺转移生长增加。发现在EphA2高/ ephrinA1低细胞中EphA2介导的集落形成是Akt依赖性的，并通过添加ephrinA1-Fc被抑制。IHC对原发性黑色素瘤标本的染色显示，EphA2高/ ephrinA1低的患者比EphA2高/ ephrinA1高的患者表现较差。

结论

根据我们的数据，我们得出结论，对ephrinA1的水平评估可能有助于以EphA2为目标的疗法的应用以及对黑色素瘤患者的预后预测。