STRUCTURE FUNCTION STUDY OF A NOVEL TUMOR SUPPRESSOR, EPHA

这个子项目是许多利用资源的研究子项目之一 由NIH/NCRR资助的中心拨款提供。子项目的主要支持 而子项目的主要调查员可能是由其他来源提供的， 包括其它NIH来源。 列出的子项目总成本可能 代表子项目使用的中心基础设施的估计数量， 而不是由NCRR赠款提供给子项目或子项目工作人员的直接资金。 在一项对约150例滤泡性淋巴瘤进行的阵列CGH研究中，我们发现约20-25%的病例中存在影响6 q21 -25染色体的复发性缺失，并且随着肿瘤分级的增加而增加。使用短发夹RNA（shRNA）文库筛选，我们确定EphA作为一种新的肿瘤抑制基因，这种缺失的目标。EphA表现为经典的肿瘤抑制因子，其余等位基因受到广泛的甲基化。此外，EphA的敲低加速滤泡性淋巴瘤小鼠模型中的肿瘤发展。引人注目的是，在正常淋巴细胞中，我们发现EphA的截短和分泌形式的表达，其作用是抑制淋巴细胞中的致癌信号传导途径。总之，这些发现指出EphA作为参与淋巴瘤发生和进展的可溶性分泌型肿瘤抑制蛋白。 我们现在提出a）检查EphA损失和外源性重建在鼠淋巴瘤模型中的作用，B）研究可溶性和全长EphA受体的结构，和c）使用质谱来描绘这种新的肿瘤抑制途径的信号传导结果。 我们希望我们的研究将为新型EphA肿瘤抑制剂提供新的见解。值得注意的是，该途径由分泌形式的EphA触发，这表明外源性EphA（或类似物）的施用可以重新激活该途径并在肿瘤中产生治疗效果。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. In an array CGH study on ~150 follicular lymphomas we found recurrent deletions affecting Chr. 6q21-25 in ~20-25% of cases and increasing with tumor grade. Using a short hairpin RNA (shRNA) library screen we identify EphA as a novel tumor suppressor gene targeted by this deletion. EphA behaves as a classical tumor suppressor and the remaining allele is subject to extensive methylation. Moreover, knockdown of EphA accelerates tumor development in a mouse model of follicular lymphoma. Strikingly, in normal lymphocytes we find expression of truncated and secreted form of EphA, which acts inhibit oncogenic signaling pathways in lymphocytes. Together, these findings point to EphA as a soluble secreted tumor suppressor protein involved in lymphomagenesis and progression. We now propose to a) examine the effects of EphA loss and exogenous reconstitution in murine lymphoma models, b) study the structures of soluble and full length EphA receptors, and c) use mass spectrometry to delineate the signaling consequences of this novel tumor suppressor pathway. We expect our study will provide new insight into the novel EphA tumor suppressor. Notably, this pathway is triggered by a secreted form of EphA, which indicates that administration of exogenous EphA (or analogues) could re-activate this pathway and produce therapeutic effects in tumors.