Intracellular trafficking of Bisphosphonates in bone mesenchymal Stem Cells

描述（由申请人提供）：含氮双膦酸盐（n-BP）有效控制骨转换失调、癌症转移的溶骨性病变，并具有抗肿瘤活性。不幸的是，颌骨骨坏死（ONJ）是n-BP治疗的主要并发症。n-BP相关骨坏死的颌骨特异性位置的原因尚不清楚，这使得设计靶向治疗具有挑战性。n-BP通过阻断甲羟戊酸信号通路中的法尼基焦磷酸（FPP）合酶作用于破骨细胞和癌细胞;结果是小GT3信号蛋白的异戊烯化丧失以及细胞存活和分化的失调。我们已经表明，口面骨髓基质细胞或骨髓间充质干细胞（BMSCs）从神经嵴来源的上颌骨/下颌骨（OFMSCs）是高度增殖与长期人口doubledge相对于中胚层来源的髂骨（ICMSCs）和长骨（LBMSCs）。因此，它们可能容易屈服于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，这是基于n-BP摄取增强，从胞质溶胶中消除缓慢，存活率降低和成骨分化降低。我们假设OFMSC对n-BP的敏感性部分地导致了ONJ的启动，这是基于位点依赖性的n-BP摄取、细胞内加工、甲羟戊酸途径中FPP合酶的抑制以及随后小GT3信号蛋白的异戊烯化的损失。在目标1中，我们将确定OFMSC中n-BP的摄取和细胞内运输如何调节存活，目标2将探索基于BMSC的治疗以预防小动物模型中的ONJ。目标是制定ONJ的预防措施。 公共卫生相关性：双膦酸盐是治疗癌症转移相关骨并发症的有效方法，但主要并发症是颌骨坏死。我们想了解颌骨干细胞如何容易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.