Project 2: Effect of HTLV-1 Viral Oncogenes on the Bone Microenvironment during tumor growth and progression in ATL

项目概要-项目2 成人T细胞白血病/淋巴瘤（ATL）在HTLV-1感染的人群中发展，是一种侵袭性淋巴瘤。 T细胞恶性肿瘤ATL与骨的独特关系（在骨髓中的长潜伏期、骨侵袭、溶骨性 病变和高钙血症）使其成为剖析支持肿瘤发展的关键因素的理想模型 和骨骼的进展。因此，我们对ATL的研究可能会揭示其他晚期复发性和向骨性 比如多发性骨髓瘤乳腺癌和前列腺癌使用转基因小鼠，我们发现HTLV-1 Tax病毒癌基因可通过影响 骨吸收破骨细胞（OC）。然而，Tax表达在约70%的人ATL中下调，尽管 持续的骨受累和骨丢失，表明另一个病毒因素是重要的。最近，我们发现 HBZ是第二种HTLV-1癌基因，也可导致淋巴组织增生性疾病和病理性骨丢失， 当以转基因方式表达或在HTLV-1感染的人源化小鼠模型中表达时。RANKL发挥着重要的 在这个过程中的作用，但不是HBZ的直接目标。我们和其他人发现，HBZ上调表达， Wnt 5a和乙酰肝素酶（HPSE），调节肿瘤微环境的肿瘤源性旁分泌因子， 在患者ATL细胞中上调。Wnt 5a通过Ror 2激活非经典Wnt信号传导， 成骨细胞抑制和OC刺激活性，包括增加RANKL表达。HPSE 酶促切割硫酸乙酰肝素，从而改变细胞表面和细胞外基质， 生长因子和细胞因子（包括RANKL和可能的Wnt 5a）的生物利用度。我们假设hbz 在转化的ATL细胞中的表达通过增加Wnt 5a和 乙酰肝素酶表达，从而影响肿瘤进展和骨丢失。 我们评估这一假设的计划完全依赖于在研究期间开发的体内模型。 上一个资助期，包括导致全身性骨丢失的新患者源性异种移植物（PDX）模型 腹膜内（IP）植入后的小鼠和新表征的已建立ATL的局部骨效应 细胞系植入骨中（胫骨内注射; IT）。我们将广泛使用病毒载体 在这些ATL和PDX系中操纵Wnt 5a和HPSE，主要是用CRISPR/Cas9， Yoder博士的专业知识（Vector Core 1）。与Niewiesk博士（动物核心2）合作，我们还 实施了人源化免疫系统（HIS）模型，其中免疫缺陷小鼠移植了 人脐带血细胞，然后用HTLV-1感染，造模出现淋巴增生性疾病 (LPD)并伴有全身性骨质流失。这项合作将是我们实验设计的关键部分。

PROJECT SUMMARY – PROJECT 2 Adult T-cell leukemia/lymphoma (ATL) develops in a subset of people infected with HTLV-1 and is an aggressive T-cell malignancy. ATL’s unique relationship to bone (long latency in the marrow, bone invasion, osteolytic lesions, and hypercalcemia) makes it an ideal model to dissect the critical factors that support tumor development and progression in bone. Thus, our work on ATL will likely shed light on other late recurring and bone-tropic tumors like multiple myeloma, breast, and prostate cancer. Using transgenic mice, we showed that the HTLV-1 tax viral oncogene can mediate both ATL development as well as osteolytic bone destruction through effects on bone-resorbing osteoclasts (OCs). However, Tax expression is downregulated in ~70% of human ATL, despite ongoing bone involvement and bone loss, suggesting that another viral factor is important. Recently, we found that HBZ, a second HTLV-1 oncogene, can also lead to lymphoproliferative disease and pathologic bone loss when expressed transgenically or in a humanized mouse model of HTLV-1 infection. RANKL plays an important role in this process, but is not a direct target of HBZ. We and others find that HBZ upregulates the expression of Wnt5a and heparanase (HPSE), tumor-derived paracrine factors that modulate the tumor microenvironment in bone and are upregulated in patient ATL cells. Wnt5a activates noncanonical Wnt signaling via Ror2 and has both osteoblast-inhibiting and OC-stimulating activities, including increasing RANKL expression. HPSE enzymatically cleaves heparan sulfate, thereby altering cell surfaces and extracellular matrix, increasing bioavailability of growth factors and cytokines including RANKL and likely Wnt5a. We hypothesize that hbz expression in transformed ATL cells reprograms the bone microenvironment via increasing Wnt5a and Heparanase expression, and thereby affects tumor progression and bone loss. Our plan for evaluating this hypothesis relies integrally on the in vivo models that were developed during the previous funding period, including new patient-derived xenograft (PDX) models that cause systemic bone loss in mice following intraperitoneal (IP) implantation and newly characterized local bone effects of established ATL cell lines following implantation into bone (with intratibial injection; IT). We will make extensive use of viral vectors to manipulate Wnt5a and HPSE in these ATL and PDX lines, primarily with CRISPR/Cas9, taking advantage of the expertise of Dr. Yoder (Vector Core 1). In collaboration with Dr. Niewiesk (Animal Core 2), we have also implemented a humanized immune system (HIS) model in which immunodeficient mice are transplanted with human cord blood cells, and then infected with HTLV-1, modeling emergence of lymphoproliferative disease (LPD) accompanied by systemic bone loss. This collaboration will be a key part of our experimental design.