Osteosarcoma Translational Research

描述（由申请人提供）：本项目旨在确定软骨细胞成熟在骨肉瘤（OS）肿瘤发生中的作用。长期目标是提高OS的诊断和确定新的OS治疗靶点。骨肉瘤是儿童和年轻人中最常见的骨癌。它也是这一年龄组癌症死亡的主要原因。操作系统开发的原因尚不清楚。由于骨肉瘤的特征是肿瘤组织中骨形成异常，而骨肉瘤的主要细胞类型是成骨细胞，因此已有研究表明成骨细胞活性在其肿瘤发生中的重要性。然而，除了成骨细胞外，其他类型的细胞如软骨细胞、脂肪细胞和成纤维细胞也出现在骨肉瘤中。这些细胞类型如何参与OS的发病机制尚不清楚。此前，在小鼠和人类骨肉瘤组织中均有软骨形成的报道（Walkley et al., 2008）。这很有趣，因为软骨形成是软骨内骨形成的重要步骤，这表明它在骨肉瘤的发展中可能起作用。在本研究中，研究人员假设软骨细胞成熟是软骨内成骨过程中软骨发育的关键阶段，可能通过与软骨细胞凋亡相关的机制在骨肉瘤的发生和发展中发挥作用。为了验证上述假设，研究人员建议使用已建立的小鼠骨肉瘤模型和他们自己的新型转基因小鼠模型以及人类骨肉瘤组织样本来描述软骨细胞成熟与骨肉瘤发展的相关性。最近，来自首席研究者小组的初步结果和/或即将发表的数据表明，在肥大软骨细胞中过度表达Runx2或P63的转基因小鼠分别导致软骨细胞成熟延迟或加速。考虑到Runx2和P63基因在骨骼和癌症形成过程中的重要功能，这些小鼠模型提供了独特的资源，可以从遗传学角度确定软骨细胞成熟如何影响p53和pRb缺陷OS小鼠模型中的OS进展（Walkley等，2008）。提出了三个具体目标。Aim1预计将表明Col10a1-Runx2小鼠的软骨细胞成熟延迟将加速OS的发生和进展，这是由于抗凋亡标记基因的表达增加。Aim2有望显示Col10a1- TAP63？小鼠延缓OS的发展，可能通过促凋亡机制。Aim 3侧重于利用组织阵列、qRT-PCR和新型COLD-PCR方法分析人类OS组织中与OS发病机制和软骨细胞成熟相关的候选基因（如P53、P63、RB1、SOX9、RUNX2等）。这些目标的成功完成将促进我们对骨肉瘤病因的理解，并确定软骨细胞成熟启动子作为骨肉瘤的新治疗靶点。

DESCRIPTION (provided by applicant): This project aims to determine how chondrocyte maturation plays a role in osteosarcoma (OS) oncogenesis. The long term goals are to advance the diagnosis of OS and to identify novel therapeutic targets for OS treatment. OS is the most common bone cancer in children and young adults. It is also the leading cause of cancer death in this age group. The causes of OS development are unknown. Previous studies have suggested the importance of osteoblast activity in its tumorigenesis, since the characteristic feature of OS is the abnormal bone formation in its tumor tissue and the predominant cell type within OS is osteoblast. However, besides osteoblasts, other cell types such as chondrocytes, adipocytes, and fibroblasts also appear within OS. How these cell types contribute to OS pathogenesis remain poorly understood. Previously, cartilage formation has been reported both in mouse and in human OS tissues (Walkley et al., 2008). This is intriguing, since cartilage formation is an essential step of endochondral bone formation, suggesting its putative role in OS development. In this application, the investigators hypothesize that chondrocyte maturation, a critical stage of cartilage development during endochondral bone formation, plays a role in the initiation and progression of OS, possibly through a mechanism relating to chondrocyte apoptosis. To test above hypothesis, the investigators propose to delineate the correlation of chondrocyte maturation with OS development using established mouse OS models and their own novel transgenic mouse models, as well as human OS tissue samples. Recently, preliminary results and/or pending publishing data from the principal investigator's group have shown that transgenic mice overexpressing Runx2 or P63 in hypertrophic chondrocytes result in delayed or accelerate chondrocyte maturation respectively. Given the important function of Runx2 and P63 genes during bone and cancer formation, these mouse models provide unique resources to genetically determine how chondrocyte maturation affects OS progression in a p53 and pRb deficient OS mouse model (Walkley et al., 2008). Three specific aims are proposed. Aim1 is expected to show that delayed chondrocyte maturation in Col10a1-Runx2 mice will accelerate OS initiation and progression due to increased expression of anti- apoptotic marker genes. Aim2 is expected to show that accelerate chondrocyte maturation in Col10a1- TAP63? mice delays OS development, possibly through a proapoptotic mechanism. Aim 3 focuses on analysis of candidate genes (such as P53, P63, RB1, SOX9, RUNX2, etc.), relating to both OS pathogenesis and chondrocyte maturation, in human OS tissues using tissue-array, qRT-PCR and novel COLD-PCR approaches. Successful completion of these aims will advance our understanding of OS etiology and identify promoters of chondrocyte maturation as novel therapeutic targets for OS. PUBLIC HEALTH RELEVANCE: In their research, the investigators proposed to delineate how chondrocyte maturation is involved in osteosarcoma (OS) pathogenesis using their novel Col10a1-Runx2/P63 transgenic mouse models. These novel mouse models show either delayed or accelerated chondrocyte maturation and therefore, provide unique genetic tool to determine the contribution of chondrocyte maturation to OS development by monitoring OS progression in a recently defined p53/pRb deficient OS mouse model. Successfully accomplishing this project will significantly advance our understanding of OS etiology and possibly, identify promoters of chondrocyte maturation as novel therapeutic targets for OS treatment.