Biological Definition of FCRL Molecules in Malignancy

描述（由申请人提供）：B细胞慢性淋巴细胞白血病（B-CLL）是西方国家最常见的白血病，其特征在于免疫球蛋白重链可变区（IgVH）基因突变状态不同的两种亚型。虽然具有突变的IgVH基因（MT-CLL）的患者通常具有大于25年的惰性病程，具有最小的治疗干预，但携带未突变的IgVH基因（UM-CLL）的个体经历更积极的过程，即使在强化治疗后中位生存期也为8年。尽管存在这些差异，但B-CLL细胞在转录和表型上类似于记忆B谱系细胞。由于IgVH区域的基因分型对于大多数临床实验室来说是昂贵的并且在技术上具有挑战性，因此正在研究突变状态的替代标志物。发现ZAP-70 Syk家族酪氨酸激酶的表达与UM-CLL最相关，使得患者能够分层为惰性或更具侵袭性的队列;然而，通过流式细胞术分析这种细胞质标志物产生了技术挑战，导致诊断变异性。Fc受体样分子（FCRL 1 -5）家族的鉴定为研究开启了一个新的领域，该家族具有独特的B细胞表达和基于酪氨酸的信号传导功能。我们研究的长期目标是确定FCRL分子在正常免疫中的生物学作用，并研究它们的功能如何在恶性肿瘤中被破坏。我们的初步数据表明MT-CLL上五种FCRL蛋白中的四种优先过表达。值得注意的是，在>100个UM-CLL和MT-CLL细胞样品上FCRL 2的表面表达的流式细胞术分析表明与MT-CLL的强一致性和预测早期治疗时间的能力。我们假设FCRL 2可以用作B-CLL的替代预后标志物，并且FCRL 2的细胞表面表达的流式细胞术分析不仅提供适合于临床实验室的稳健测定，而且还将扩展B-CLL诊断的能力。这将在两个特定目的中进行测试：1）通过流式细胞术优化B-CLL细胞上的FCRL 2检测和测定的标准化;和2）FCRL 2表达对于预测IgVH突变状态和B-CLL中的疾病进展的预后重要性的内部和外部验证。重要性：使用常规临床流式细胞术检测FCRL 2表面表达的评估可以极大地促进B-CLL的预后，从而显著改善这种白血病患者的整体护理。此外，我们预计这些研究将通过提供有关侵袭性亚型的新见解来扩展B-CLL预后的能力，这最终可能有助于确定治疗干预的最佳时机。公共卫生相关性：本研究旨在探讨Fc受体样分子（FCRL）家族在西方国家最常见的白血病B细胞慢性淋巴细胞白血病（B-CLL）中的表达。FCRL蛋白似乎优先在惰性形式的疾病中过表达。这项工作将研究其中一些分子是否可以作为B-CLL的新型预后标志物，并取代或补充当前疾病侵袭性的指标。

DESCRIPTION (provided by applicant): B cell chronic lymphocytic leukemia (B-CLL), the most prevalent leukemia in Western countries, is characterized by two subtypes that differ in the mutation status of their immunoglobulin heavy-chain variable region (IgVH) gene. While patients with mutated IgVH genes (MT-CLL) typically have an indolent disease course of greater than 25 years with minimal therapeutic intervention, individuals harboring unmutated IgVH genes (UM-CLL) experience a more aggressive process with a median survival of 8 years even after intensive treatment. Despite these differences, B-CLL cells transcriptionally and phenotypically resemble memory B lineage cells. As genotyping of IgVH regions is costly and technically challenging for most clinical laboratories, surrogate markers for mutation status are being investigated. Expression of the ZAP-70 Syk family tyrosine kinase was found to best correlate with UM-CLL, enabling the stratification of patients into indolent or more aggressive cohorts; however, analysis of this cytoplasmic marker by flow cytometry has created technical challenges resulting in diagnostic variability. The identification of a family of Fc receptor-like molecules (FCRL1-5) with distinct B cell expression and tyrosine-based signaling function opens a new field of study. The long term goal of our studies is to determine the biological role of FCRL molecules in normal immunity and investigate how their functions may be subverted in malignancy. Our preliminary data indicate preferential overexpression of four of five FCRL proteins on MT-CLL. Notably, flow cytometric analysis of the surface expression of FCRL2 on >100 UM-CLL and MT-CLL cell samples indicated strong concordance with MT-CLL and an ability to predict early time to therapy. We hypothesize that FCRL2 can be used as a surrogate prognostic marker in B-CLL and that flow cytometric analysis of cell surface expression of FCRL2 will not only provide a robust assay suitable for clinical laboratories, but will also extend the capabilities of B-CLL diagnosis. This will be tested in two Specific Aims: 1) Optimization of FCRL2 detection on B-CLL cells by flow cytometry and standardization of the assay; and 2) Internal and external validation of the prognostic importance of FCRL2 expression for predicting IgVH mutation status and disease progression in B-CLL. Significance: The assessment of FCRL2 surface expression using routine clinical flow cytometry assays could greatly facilitate prognosis in B-CLL and, thus, significantly improve the overall care of patients with this leukemia. In addition, we anticipate that these studies will extend the capabilities of B-CLL prognosis by providing new insights concerning the aggressive subtype, which ultimately could assist in determination of the optimal timing of therapeutic intervention. PUBLIC HEALTH RELEVANCE: This proposal will investigate the expression of a recently described family of Fc receptor-like molecules (FCRL) in the most prevalent leukemia in Western countries, B cell chronic lymphocytic leukemia (B-CLL). FCRL proteins appear to be preferentially overexpressed in the indolent form of the disease. This work will investigate whether some of these molecules may serve as novel prognostic markers in B-CLL and replace or supplement current indicators of disease aggressiveness.