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

 描述(由申请人提供)：IRF4对许多免疫细胞群对病原体的反应的分化和效应功能是必不可少的。在B细胞室中，IRF4是浆细胞(PC)分化的关键诱导者，IRF4活性的解除与从自身免疫到B细胞恶性肿瘤的多种病理过程有关。在B细胞恶性肿瘤中，ABC亚型弥漫性大B细胞淋巴瘤(DLBCL)尤其具有侵袭性，其特征是控制PC分化的分子网络包括IRF4的失调控。对控制IRF4活性的分子机制的详细了解可以为开发治疗ABC-DLBCL的新疗法提供重要的见解。此前，我们的实验室发现，在Th17分化过程中，IRF4被丝氨酸苏氨酸激酶ROCK2磷酸化，并且这个ROCK2-pIRF4轴在几种自身免疫模型中驱动IL-17和IL-21的异常产生。与这一发现一致的是，用法舒地尔对ROCK进行药理抑制可以改善易患狼疮的MRL/LPR和NZB/W F1小鼠以及关节炎Def6/-DO11.10小鼠的疾病。虽然之前的研究描绘了Th17细胞中ROCK-pIRF4轴，但我们正在探索ROCK在免疫调节中发挥更多全球作用的可能性。支持这一观点，我们发现用aCD40和IL-21刺激B细胞会导致ROCK2的激活和IRF4的磷酸化。我们进一步发现，IRF4在ABC-DLBCL中被选择性地磷酸化，但在其他DLBCL亚型中不被磷酸化，包括GCB-DLBCL。重要的是，我们已经评估了ABC-DLBCL中岩石活性的功能相关性，并发现对岩石的抑制在ABC-DLBCL中诱导选择性致死。因此，我们现在提出，在ABC-DLBCL中，ROCK2对IRF4的磷酸化促进了IRF4的致癌功能，ROCK抑制可能代表了ABC-DLBCL的一种新的治疗方法。该建议的具体目标是：1)剖析ROCK2激活在ABC-DLBCL中的作用，2)研究IRF4磷酸化在ABC-DLBCL中的功能后果，3)广泛评估ROCK2激活和IRF4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，同时只显示出最小的副作用，从这项建议中描述的研究中获得的知识可能会迅速转化为治疗ABC-DLBCL的新治疗方案。

 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.