SFRP2 and NFAT are Therapeutic Targets in Angiosarcoma

血管肉瘤是一种生物侵袭性的血管恶性肿瘤，具有高转移潜能和 后续死亡率(1)。在诊断血管肉瘤时，10�25%的患者已经 转移性疾病。所有血管肉瘤患者的2年和5年总存活率分别为50%和30%， 中位总生存期为24个月。对于不可切除的血管肉瘤，以阿霉素为基础的 方案的无进展生存期为5个月，紫杉醇的无进展生存期为7个月 月(2)。因此，迫切需要新的治疗方法来提高本病患者的存活率。 高度致命的疾病。我们实验室最近发现了一条新的信号通路，负责 血管肉瘤生长。进行乳腺肿瘤血管细胞基因组图谱时与正常对照 通过激光捕获显微解剖获得的血管，我们鉴定了分泌型卷曲相关蛋白2(SFRP2)是 一个在肿瘤内皮细胞中表达增加的基因。SFRP2是一种33kd的分泌蛋白，与Wnt有关 发信号。我们的初步数据显示，9/9的人血管肉瘤中存在SFRP2蛋白，并且 刺激鸡胚绒毛尿囊膜血管生成，诱导内皮细胞迁移和管状 形成，并对缺氧诱导的细胞凋亡具有保护作用。SVR血管肉瘤细胞中SFRP2的沉默 结果抑制了管子的形成，而SFRP2刺激内皮细胞导致了增加 在核NFATc3中。NFAT是一种转录因子，在介导血管生成中起关键作用 回应(3；4)。NFAT核本地化取决于进出口之间的动态平衡 钙/钙调素依赖的磷酸酶、钙调神经磷酸酶和丝氨酸/苏氨酸的活性 激酶(20)。NFAT在正常情况下不能进入细胞核，直到它被去磷酸化，但可以被激活 钙调神经磷酸酶。激活的钙调神经磷酸酶使NFAT去磷酸化，然后NFAT从细胞质转移到 细胞核并导致参与细胞生长、分化和细胞周期进程的基因的转录。 他克莫司(FK506)是一种免疫抑制药，能与淋巴细胞中的免疫亲和素FKBP12结合。 FK506-FKBP12复合体与钙调神经磷酸酶结合并抑制其磷酸酶活性，从而抑制 NFAT的核转位(5)。我们的初步数据显示他克莫司抑制血管肉瘤试管 体外形成和全身给药抑制SVR血管肉瘤裸鼠移植瘤的生长 小鼠在20日龄时减少46%。综上所述，我们的数据使我们提出了以下假设：封锁 SFRP2将减少血管生成和血管肉瘤生长，并将协同促进肿瘤消退 同时配合化疗和抗血管生成治疗。这项研究的目的是表明 这些药物单独治疗血管肉瘤以及与化疗和抗血管生成药物联合治疗的疗效 并阐明其抑制肿瘤生长的分子机制。圆满完成 该项目将在未来的研究中导致这些药物在血管肉瘤患者中的临床试验。

Angiosarcoma is a biologically aggressive vascular malignancy with a high metastatic potential and subsequent mortality(1). At the time of diagnosis of angiosarcoma, 10� 25% of patients already have metastatic disease. The 2- and 5-year overall survival for all patients with angiosarcoma is 50 and 30%, respectively, with a median overall survival of 24 months. For unresectable angiosarcoma, doxorubicin based regimens yield progression-free survival of 5 months, and paclitaxel achieves a progression-free survival of 7 months(2). Therefore there is a desperate need for novel therapies to improve survival in patients with this highly lethal disease. Our laboratory has recently discovered a novel signaling pathway responsible for angiosarcoma growth. While conducting genomic profiling of breast tumor vascular cells compared to normal vessels obtained by laser capture microdissection, we identified secreted frizzled related protein 2 (SFRP2) as a gene with increased expression in tumor endothelium. SFRP2 is a 33kd secreted protein involved in Wnt signaling. Our preliminary data shows that SFRP2 protein is present in 9/9 human angiosarcomas by IHC, and stimulates angiogenesis on the chick chorioallantoic membrane, induces endothelial cell migration and tube formation, and protects against hypoxia induced apoptosis. Silencing of SFRP2 in SVR angiosarcoma cells resulted in inhibition of tube formation, and stimulation of endothelial cells with SFRP2 resulted in an increase in nuclear NFATc3. NFAT is a transcription factor that plays a critical role in mediating angiogenic responses(3;4). NFAT nuclear localization is dependent on a dynamic import-export balance between the activity of the Ca2+/calmodulin-dependent phosphatase, calcineurin, and the activity of serine/threonine kinases(20). NFAT cannot normally enter the nucleus until it is dephosphorylated, but can be activated by calcineurin. Activated calcineurin dephosphorylates NFAT, which then translocates from the cytoplasm to the nucleus and results in transcription of genes involved in cell growth, differentiation, and cell cycle progression. Tacrolimus (FK506) is an immunosuppressive drug that binds to the immunophlin FKBP12 in lymphocytes. The FK506-FKBP12 complex associates with calcineurin and inhibits its phosphatase activity, which inhibits nuclear translocation of NFAT(5). Our preliminary data shows that tacrolimus inhibits angiosarcoma tube formation in vitro, and systemic administration inhibits the growth of the SVR angiosarcoma xenograft in nude mice by 46% at 20 days. Taken together, our data leads us to propose the following hypothesis: Blockade of SFRP2 will decrease angiogenesis and angiosarcoma growth and will synergistically improve tumor regression in combination with both chemotherapy and antiangiogenic therapy. The objective of this study is to show the efficacy of these drugs in angiosarcoma alone, and in combination with chemotherapy and antiangiogenic therapy, and to elucidate their molecular mechanism in inhibiting tumor growth. Successful completion of the project will lead to clinical trials of these agents in patients with angiosarcoma in future studies.