Significance and Function of HGAL in Lymphoma

描述（由申请人提供）：本项目基于我们的发现，即人类生殖中心相关淋巴瘤（HGAL）的高表达-我们克隆和表征的一种新基因-是弥漫性大B细胞淋巴瘤（DLBCL）和霍奇金病（HD）患者生存期延长的独立预测因子。 最近，我们证明了HGAL介导IL-6诱导的对生发中心（GC）B细胞迁移的抑制。 我们证明IL-6诱导HGAL C-末端酪氨酸的Lyn-mediated磷酸化，并导致HGAL重新定位于podosome样结构和spike样丝状伪足。 我们发现内源性HGAL和肌球蛋白II之间的相互作用和划定的HGAL结构域负责的相互作用。 我们提供了HGAL磷酸化导致与肌球蛋白II的相互作用增加的证据，并证明内源性HGAL的敲低改善了IL-6对细胞迁移的抑制作用。 综上所述，这些结果确定HGAL作为IL-6对淋巴细胞迁移的作用的生理介质，并表明HGAL在GC衍生的淋巴瘤中的表达可能限制肿瘤扩散并倾向于更好的临床结果。 然而，尽管在鉴定HGAL在细胞过程中的作用方面取得了显著进展，但HGAL介导的细胞迁移抑制的精确机制以及表达HGAL的肿瘤的更好临床结果的随后倾向目前尚不清楚。 我们的初步数据表明，HGAL可能会影响细胞运动与肌球蛋白II和/或通过增加RhoA活性。 然而，这些影响需要进一步研究。 在这个项目中，我们将：1）确定HGAL对肌球蛋白II功能的影响; 2）确定HGAL对小Rho GT3家族的成员- RhoA蛋白及其效应物的影响; 3）确定HGAL豆蔻酰化和棕榈酰化对其对细胞运动性的抑制作用的作用;和4）确定转基因小鼠模型中HGAL表达对淋巴细胞分化、成熟、运动性和淋巴瘤发生的影响。 这些研究将扩大我们对GC淋巴细胞的生物学知识，特别强调淋巴细胞的运动和迁移。 此外，这些研究将揭示潜在的新机制，调节淋巴肿瘤的传播和发展。 这些机制的研究可能为新的治疗方法提供新的途径。 公共卫生相关性：在诊断时预测患者结局的能力至关重要。 我们以前克隆了一个新的基因- HGAL，它被证明是霍奇金淋巴瘤和非霍奇金淋巴瘤的一个重要的预后生物标志物。 我们以前已经表明，HGAL抑制肿瘤的迁移和传播。 在此，我们将研究HGAL诱导的细胞迁移抑制的分子机制。 这些发现不仅将阐明肿瘤扩散的机制，而且将为新的治疗干预确定新的潜在分子靶点。

DESCRIPTION (provided by applicant): This project is based on our findings that high expression of Human Germinal center Associated Lymphoma (HGAL) - a new gene that we cloned and characterized - is an independent predictor of prolonged survival of diffuse large B cell lymphoma (DLBCL) and Hodgkin's disease (HD) patients. Recently, we demonstrated that HGAL mediates IL-6-induced inhibition of germinal center (GC) B-cell migration. We demonstrated that IL-6 induces Lyn-mediated phosphorylation of the HGAL C-terminal tyrosine and causes HGAL relocalization to podosome-like structures and spike-like filopodia. We showed interactions between endogenous HGAL and myosin II and delineated HGAL domains responsible for the interaction. We provided evidence that HGAL phosphorylation results in increased interaction with the myosin II and demonstrated that knockdown of endogenous HGAL ameliorates the inhibitory effects of the IL-6 on cell migration. Taken together, these results identified HGAL as a physiological mediator of IL-6 effects on lymphocyte migration and suggest that HGAL expression in GC-derived lymphomas may limit tumor dissemination and predispose to better clinical outcome. However, despite the marked progress in identifying HGAL role in cellular processes, the precise mechanisms of HGAL-mediated inhibition of cell migration and consequent predisposition to better clinical outcome of tumors expressing HGAL are presently unknown. Our preliminary data demonstrates that HGAL may affect cell motility by interacting with myosin II and/or by increasing RhoA activity. However, these effects need to be further investigated. In this project we will: 1) Determine effects of HGAL on myosin II function; 2) Determine effects of HGAL on a member of the small Rho GTPase family - RhoA protein and its effectors; 3) Determine the role of HGAL myristoylation and palmytoylation on its inhibitory effects on cell motility; and 4) Determine the effects of HGAL expression in transgenic mice model on lymphocyte differentiation, maturation, motility and lymphomagenesis. These studies will expand our knowledge on biology of the GC lymphocytes, with specific emphasis on lymphocyte motility and migration. Furthermore, these studies will reveal potentially new mechanisms regulating dissemination and progression of lymphoid tumors. These mechanistic studies may provide novel approaches for new therapeutic. PUBLIC HEALTH RELEVANCE: Ability to predict patients' outcome at the time of diagnosis is of paramount significance. We have previously cloned a new gene - HGAL that was demonstrated to be an important prognostic biomarker in Hodgkin's and non-Hodgkin's lymphomas. We have shown previously that HGAL inhibit tumors migration and dissemination. Herein we will investigate molecular mechanisms of HGAL-induced inhibition of cell migration. These findings will not only elucidate the mechanisms of tumor dissemination but also will identify a new potential molecular target for novel therapeutic intervention.