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

项目摘要--项目2 成人T细胞白血病/淋巴瘤(ATL)发生在感染HTLV-1的人群中，是一种侵袭性疾病 T细胞恶性病变。ATL与骨的独特关系(骨髓潜伏期长，骨侵袭，溶骨 损伤和高钙血症)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，我们在ATL方面的工作可能会为其他晚期复发和嗜骨性疾病提供帮助。 多发性骨髓瘤、乳腺癌和前列腺癌等肿瘤。使用转基因小鼠，我们发现HTLV-1 TAX病毒癌基因可通过影响ATL发生和溶骨性骨破坏来介导ATL的发展 骨吸收破骨细胞(OCS)。然而，在约70%的人类ATL中，Tax的表达下调，尽管 持续的骨侵犯和骨丢失，表明另一个病毒因素是重要的。最近，我们发现 第二个HTLV-1癌基因HBZ也可以导致淋巴增生性疾病和病理性骨丢失 当转基因表达或在HTLV-1感染的人源化小鼠模型中表达时。RANKL扮演着重要的角色 在这一进程中发挥作用，但不是HBZ的直接目标。我们和其他人发现，HBZ上调了 Wnt5A和肝素酶(HPSE)，肿瘤来源的旁分泌因子，调节肿瘤微环境 骨，并在患者的ATL细胞中上调。WNT5A通过Ror2激活非规范Wnt信号，并具有 既有成骨细胞抑制活性，也有OC刺激活性，包括增加RANKL表达。HPSE 酶促裂解硫酸乙酰肝素，从而改变细胞表面和细胞外基质，增加 生长因子和细胞因子的生物利用度，包括RANKL和可能的WNT5a。我们假设hbz 转化的ATL细胞中的表达通过增加Wnt5a和Wnt5a而重新编程骨微环境 乙酰肝素酶的表达，从而影响肿瘤的进展和骨丢失。 我们评估这一假说的计划完全依赖于在 之前的资助期，包括导致全身骨丢失的新的患者来源的异种移植(PDX)模型 小鼠腹膜内植入ATL后局部骨骼效应的新特征 植入骨内后的细胞系(通过骨内注射；IT)。我们将广泛使用病毒载体 要操纵这些ATL和PDX线路中的Wnt5a和HPSE，主要是使用CRISPR/Cas9，利用 约德博士(向量核心1)的专业知识。在与Niewiesk博士(动物核心2)的合作下，我们还 实施了人源化免疫系统(HIS)模型，将免疫缺陷小鼠移植到 人脐血细胞，然后感染HTLV-1，模拟淋巴增殖性疾病的出现 (LPD)伴有全身性骨丢失。这一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.