Role of mRNA stabilizing proteins during macrophage polarization and implications for tumor development

凋亡细胞的条件培养基（CM）使巨噬细胞（Mφ）朝向促血管生成表型极化，其与M2型Mφ和/或肿瘤相关Mφ（TAM）共享许多特征。已经证明CM激活HuR（胚胎致死性异常视觉（ELAV）样家族成员）并进而引起环氧合酶-2（考克斯-2）表达，我们假设极化Mφ的细胞因子谱的总体变化受mRNA结合蛋白（RBP）的控制。我们跟踪HuR、TTP（tristetraprolin）和AUF-1响应CM的表达和活性变化，并将它们的改变与已建立的M2/TAM标记物以及极化Mφ的功能结果相关联，以引起促血管生成反应，如增殖、出芽和血管形成。RBP的敲低将建立因果关系，并且使用RBP随后使用基因阵列的RNA免疫沉淀将用于鉴定RBP的新靶点，其有助于响应于CM的Mφ的肿瘤支持表型。使用过继性基因转移技术，我们的目的是显示巨噬细胞的功能性结果，其中HuR、TTP或AUF-1的敲低朝向体内肿瘤进展。我们预计，我们的研究将有助于理解RBP如何促进Mφ极化以响应CM，从而创造一个促肿瘤微环境。

Conditioned medium (CM) of apoptotic cells polarizes macrophages (Mφ) towards an antiinflammatory and pro-angiogenic phenotype, which shares a number of characteristics with M2-type Mφ and/or tumor associated Mφ (TAMs). Having proven that CM activates HuR (embryonic lethal abnormal vision (ELAV)-like family member) and in turn causes cyclooxygenase-2 (Cox-2) expression, we hypothesize that global changes in the cytokine profile of polarized Mφ are under the control of mRNA binding proteins (RBPs). We follow expression and activity changes of HuR, TTP (tristetraprolin) and AUF-1 in response to CM and correlate their alterations to established M2/TAM-markers as well as functional consequences of polarized Mφ to elicit pro-angiogenic responses such as proliferation, sprouting and vessel formation. Knockdown of RBPs will establish a cause-effect relation and RNA-immunoprecipitation using the RBPs followed by gene arrays will be used to identify novel targets of RBPs that contribute to a tumor supporting phenotype of Mφ in response to CM. Using the technology of adoptive gene transfer it is our intention to show a functional consequence of macrophages with a knockdown of either HuR, TTP or AUF-1 towards tumor progression in vivo. We anticipate that our study will add to the understanding how RBPs contribute to Mφ polarization in response to CM, thereby creating a tumor promoting microenvironment.