胰岛素样生长因子1受体(IGF1R)显性负性可溶性突变体对骨肉瘤作用的研究

Osteosarcoma(OS） is the most common non-hematolgic malignant tumor of bone in children and young adults. Most OS tumors are of high grade and tend to develop pulmonary metastases.With the current treatment for OS, the average 5-year disease-free survival rate is only 60- 70%, and there appears to plateau over the past three decades in survival data. Insulin-like growth factor (IGF) signaling axis plays an important role in bone development and may be associated with the pathogenesis of OS. IGF signaling pathway is activated in many cancers and emerges as promising anticancer drug targets. targeting IGF signaling for cancer treatment have been undertaken and many are ongoing, the outcomes so far have been mixed. IGF-1R is a member of the tyrosine kinase class of membrane receptors. IGF-1R is a heterotetrameric protein complex consisting of two extracellular,a-subunits and two transmembrane ,β-subunits each .We created three dominant-negative human IGF1R mutants, a soluble a-subunit of IGF1R (sa-IGF1R), a soluble β-subunit of IGF1R (sb-IGF1R), and membrane-anchored β-subunit of IGF1R (ma-IGF1R) . Although the use of dominant-negative IGF1R mutants to target IGF signaling and/or to inhibit cancer cell growth was initially reported more than a decade ago, no extensive in vivo and/or preclinical studies have been carried out. No studies have shown that targeting the β-subunit alone is sufficient to inhibit IGF signaling. Furthermore, it has not been investigated if the IGF1R mutants can be used to inhibit OS tumor growth and metastasis development and/or as or chemo-sensitizing agents. As showing in Preliminary Studies, we have demonstrated that these IGF1R mutants can inhibit OS proliferation, migration, and in vivo tumor growth . In this proposal, we will focus on the three soluble mutants, sa-IGF1R,sb-IGF1R and ma-IGF1R in consideration of their in vivo use and translational potential as OS therapeutics.

骨肉瘤是青少年最常见的非血源性的原发性恶性骨肿瘤，易形成肺部转移病灶，其治疗最近三十年来存活率几乎没有什么进展。IGF通路和骨肉瘤发生发展密切相关，是抗肿瘤药物研发的理想靶点。但已完成的和正在进行的临床研究结果却离期望相距甚远。我们提出一种全新的阻断骨肉瘤IGF信号的策略，针对IGF1受体两种亚基设计的三个“显性负性”可溶性突变体，分别为针对a亚基的sa-IGF1R和针对β亚基的sb-IGF1R和β跨膜段的ma-IGF1R，避免了对胰岛素通路的“误伤”，精确作用于IGF通路，因此具有高度的特异性和有效性，更易于转化医学应用。国内外尚无活体动物实验和临床前期实验，且没有单独针对β亚基是否可抑制IGF信号通路的研究，更没有IGF1R突变体是否可以抑制骨肉瘤的生长和转移以及起到化疗增敏剂作用的任何报道。而我们的前期结果显示三个突变体均可以有效的阻断IGF信号，并在体内外抑制骨肉瘤的生长和转移。

骨肉瘤是青少年最常见的非血源性的原发性恶性骨肿瘤，易形成肺部转移病灶，其治疗最近三十年来存活率几乎没有什么进展。IGF通路和骨肉瘤发生发展密切相关，是抗肿瘤药物研发的理想靶点。但已完成的和正在进行的临床研究结果却离期望相距甚远。我们提出一种全新的阻断骨肉瘤IGF信号的策略，针对IGF1受体两种亚基设计的三个“显性负性”可溶性突变体，分别为针对a亚基的sa-IGF1R和针对β亚基的sb-IGF1R和β跨膜段的ma-IGF1R，避免了对胰岛素通路的“误伤”，精确作用于IGF通路，因此具有高度的特异性和有效性，更易于转化医学应用。国内外尚无活体动物实验和临床前期实验，且没有单独针对β亚基是否可抑制IGF信号通路的研究，更没有IGF1R突变体是否可以抑制骨肉瘤的生长和转移以及起到化疗增敏剂作用的任何报道。而我们的结果显示三个突变体均可以有效的阻断IGF信号，并在体内外抑制骨肉瘤的生长和转移诱导凋亡。同时研究了IGF1R 三个可溶性显性负性突变体肽段抑制肿瘤生长转移和诱导凋亡的分子信号学通路及其作用机制。从机制上看，dnlGF1R突变体可以有效下调人OS细胞中PI3K/AKT和RAS/RAF/MAPK信号通路，以及BCL2、Cyclin D1和大多数EMT调控因子的表达，同时上调促凋亡基因的表达。 明显诱导下游有利肿瘤细胞凋亡的基因表达（TP53, BAX, p21 and p27），明显下调抗凋亡基因的表达（CDH2, VIM, SNAI2, ZEB1, ZEB2, ZO-1, MMP9 and MMP14）.本研究为骨肉瘤的治疗提供了新的靶向治疗的思路并研究了其机制，采用的分泌型 IGF1R 突变体作用于IGF 信号通路具有高度特异性和有效性。因此具有很高的转化医学的价值。