Intracellular trafficking of Bisphosphonates in bone mesenchymal Stem Cells

说明(申请人提供)：含氮二膦酸盐(n-BP)有效控制骨转换失调、肿瘤转移的溶骨性病变，并具有抗肿瘤活性。不幸的是，颌骨坏死(ONJ)是n-BP治疗的主要并发症。N-BP相关性骨坏死的颌骨特定部位的原因尚不清楚，这使得设计有针对性的治疗方案具有挑战性。N-BPS通过阻断甲氧戊酸信号通路中的法尼基焦磷酸(FPP)合成酶作用于破骨细胞和癌细胞；其结果是失去小GTP酶信号蛋白的预烯基化，并扰乱细胞的生存和分化。我们的研究表明，颌面部神经脊源性上颌骨(OFMSCs)来源的骨髓基质细胞或骨髓间充质干细胞(BMSCs)较中胚层来源的髂骨(ICMSCs)和长骨(LBMSCs)具有较高的增殖能力和较长的群体倍增能力。因此，它们可能很容易屈服于n-BP，类似于快速增殖的癌细胞。我们的初步研究表明，OFMSCs确实比ICMSCs对n-BP更敏感，这是因为增加了n-BP的摄取，缓慢地从细胞液中清除，降低了存活率和成骨分化。我们推测，OFMSCs对n-BP的敏感性部分地参与了ONJ的启动，其基础是位置依赖的n-BP摄取、细胞内加工、甲氧戊酸途径中FPP合成酶的抑制以及由此导致的小GTPase信号蛋白预烯基化的丧失。在目标1中，我们将确定n-BP在OFMSCs中的摄取和细胞内转运如何调节生存，目标2将探索基于骨髓间充质干细胞的治疗方法，以在小动物模型中预防ONJ。目标是为ONJ制定预防措施。 公共卫生意义：双磷酸盐是治疗与癌症转移相关的骨并发症的有效疗法，但主要并发症是颌骨坏死。我们想要了解颌骨干细胞是如何容易地屈服于双膦酸盐的影响，从而预防颌骨坏死的并发症。

DESCRIPTION (provided by applicant): Nitrogen-containing bisphosphonates (n-BP) effectively control dysregulated bone turnover, osteolytic lesions of cancer metastasis and have anti-tumor activities. Unfortunately, osteonecrosis of the jaw (ONJ) is a major complication of n-BP therapy. Reasons for jaw-specific location of n-BP related osteonecrosis are unclear making it challenging to design targeted therapies. n-BPs act on osteoclasts and cancer cells by blocking the farnesyl pyrophosphate (FPP) synthase in the mevalonate signaling pathway; the outcome is loss of prenylation of small GTPase signaling proteins and dysregulation of cell survival and differentiation. We have shown that orofacial bone marrow stromal cells or bone mesenchymal stem cells (BMSCs) from neural crest-derived maxilla/mandible (OFMSCs) are highly proliferative with long population doublings relative to those of mesoderm-derived iliac bone (ICMSCs) and long bones (LBMSCs). Therefore, they may readily succumb to n-BP similar to rapidly proliferative cancer cells. Our preliminary studies showed that OFMSCs are indeed more sensitive to n-BP than ICMSCs based on enhanced n-BP uptake, slow elimination from the cytosol, decreased survival and decreased osteogenic differentiation. We hypothesize that sensitivity of OFMSCs to n-BP contributes in part to initiation of ONJ based on site-dependent n-BP uptake, intracellular processing, inhibition of FPP synthase in the mevalonate pathway and consequent loss of prenylation of small GTPase signaling proteins. In aim 1 we will determine how uptake and intracellular trafficking of n-BP in OFMSCs modulates survival and aim 2 will explore BMSC-based therapy to prevent ONJ in a small animal model. The goal is to formulate preventive measures for ONJ. PUBLIC HEALTH RELEVANCE: Bisphosphonate is an effective therapy for bone complications associated with cancer metastasis but a major complication is jaw bone necrosis. We want to understand how jaw bone stem cells readily succumb to effects of bisphosphonate so the complication of jaw necrosis can be prevented.