Examining the Role of Rho Kinase in the Pathogenesis of ABC-DLBCL

 描述（由申请人提供）： IRF 4对于许多免疫细胞群体响应病原体的分化和效应子功能是必需的。在B细胞区室内，IRF 4是浆细胞（PC）分化的关键诱导剂，并且IRF 4活性的失调与从自身免疫到B细胞恶性肿瘤的多种病理学相关。在B细胞恶性肿瘤中，弥漫性大B细胞淋巴瘤（DLBCL）的ABC亚型特别具有侵袭性，并且特征在于控制PC分化的分子网络（包括IRF 4）中的失调。详细了解控制IRF 4活性的分子机制可以为开发治疗ABC-DLBCL的新疗法提供关键见解。以前，我们的实验室发现，在Th 17分化过程中，IRF 4被ROCK 2（一种丝氨酸-苏氨酸激酶）磷酸化，并且该ROCK 2-pIRF 4轴在几种自身免疫模型中驱动异常的IL-17和IL- 21产生。与这一发现一致，法舒地尔对ROCK的药理学抑制改善了狼疮易感MRL/lpr和NZB/W F1小鼠以及关节炎Def 6-/- DO11.10小鼠的疾病。虽然以前的研究描绘了ROCK-pIRF 4轴在Th 17细胞中，我们正在探索的可能性，ROCK在免疫调节中发挥更全面的作用。支持这一观点，我们发现用aCD 40和IL-21刺激B细胞导致ROCK 2的活化和IRF 4的磷酸化。我们还发现，IRF 4在ABC-DLBCL中选择性磷酸化，但在其他DLBCL亚型（包括GCB-DLBCL）中不磷酸化。重要的是，我们已经评估了ROCK活性在ABC-DLBCL中的功能相关性，并发现ROCK的抑制诱导ABC-DLBCL中的选择性致死。因此，我们现在提出，在ABC-DLBCL中ROCK 2对IRF 4的磷酸化促进了IRF 4的致癌功能，并且ROCK抑制可能代表ABC-DLBCL的新治疗方法。本提案的具体目标是：1）剖析ROCK 2激活在ABC-DLBCL中的作用，2）研究IRF 4磷酸化在ABC-DLBCL中的功能后果，3）广泛评估ROCK 2激活和IRF 4磷酸化在ABC-DLBCL中的作用。鉴于ROCK抑制剂已经在心血管疾病的临床试验中显示出益处，同时仅表现出最小的副作用，因此从本提案中描述的研究中获得的知识可以迅速转化为治疗ABC-DLBCL的新型治疗方案。

 DESCRIPTION (provided by applicant): IRF4 is essential for the differentiation and effector functions of many immune cell populations in response to pathogen. Within the B cell compartment, IRF4 is a critical inducer of plasma cell (PC) differentiation and deregulation in IRF4 activity has been associated with multiple pathologies ranging from autoimmunity to B cell malignancies. Among B cell malignancies, the ABC subtype of diffuse-large B cell lymphoma (DLBCL) is particularly aggressive and is characterized by deregulations in the molecular networks controlling PC differentiation, including IRF4. A detailed understanding of the molecular mechanisms that control IRF4 activity can provide critical insights for the development of novel therapies for the treatment of ABC-DLBCL. Previously, our lab discovered that IRF4 is phosphorylated by ROCK2, a serine-threonine kinase, during Th17 differentiation and that this ROCK2-pIRF4 axis drives aberrant IL-17 and IL- 21 production in several autoimmune models. Consistent with this finding, pharmacological inhibition of ROCK with Fasudil ameliorates disease in lupus-prone MRL/lpr and NZB/W F1 mice and in arthritic Def6-/- DO11.10 mice. While previous studies delineated the ROCK-pIRF4 axis in Th17 cells, we are exploring the possibility that ROCKs play more global roles in immune regulation. Supporting this notion, we found that stimulation of B cells with aCD40 and IL-21 leads to the activation of ROCK2 and to the phosphorylation of IRF4. We furthermore discovered that IRF4 is selectively phosphorylated in ABC-DLBCLs, but not in other DLBCL subtypes, including GCB-DLBCLs. Importantly, we have assessed the functional relevance of ROCK activity in ABC-DLBCL and discovered that inhibition of ROCK induces selective lethality in ABC-DLBCL. We thus now propose that phosphorylation of IRF4 by ROCK2 in ABC-DLBCL promote the oncogenic function of IRF4 and that ROCK inhibition could represent a novel therapeutic approach for ABC-DLBCL. The specific goals of this proposal are: 1) To dissect the role of ROCK2 activation in ABC-DLBCL, 2) To investigate the functional consequences of IRF4 phosphorylation in ABC-DLBCL, 3) To broadly assess the role of ROCK2 activation and IRF4 phosphorylation in ABC-DLBCL. Given that ROCK inhibitors have already shown benefits in clinical trials for cardiovascular disorders while exhibiting only minimal side effects, the knowledge derived from the studies described in this proposal could be rapidly translated into a novel therapeutic regimen for the treatment of ABC-DLBCL.