Targeting the Microenvironment for Myeloma Growth Control

多发性骨髓瘤(MM)中常见和典型的溶骨性骨病的诱发导致了骨病既是多发性骨髓瘤进展和转移的结果也是必然的概念。我们已报道的初步数据表明，破骨细胞通过产生称为二肽基肽酶-IV活性和/或结构同源蛋白(DASH)的某些丝氨酸蛋白酶来支持骨髓瘤细胞的生存和转移，而抑制破骨细胞或DASH蛋白酶的活性会抑制髓质MM的生长。相反，我们发现成骨细胞通过产生某些富含亮氨酸的蛋白多糖来抑制骨髓瘤细胞的生长，而骨髓瘤样骨中的成骨细胞活性增加(通过成骨细胞激活剂[甲状旁腺素或抗DKKI]或细胞疗法[骨祖细胞]治疗)增加了骨形成，创造了不适宜居住的微环境，从而减缓了MM在体内的进展。基于这些发现，我们假设现有局灶性病变的微环境是骨髓瘤细胞长期存活和扩散的关键决定因素；因此，同时抑制破骨细胞活性和刺激骨形成对于维持患者对治疗的反应和防止转移至关重要。在具体目标1中，我们将确定骨合成代谢药物(例如PTH、抗DKKI)在有或没有外源性成骨细胞前体的情况下增加的骨形成是否能维持临床药物(如马法兰、地塞米松、硼替佐米、来那度胺)诱导的缓解，和/或防止肿瘤复发时的转移。我们还将研究与这些效应相关的分子机制。在特定的目标2中，我们将确定破骨细胞产生的DASH蛋白水解酶是否有助于MM诱导的骨病，支持MM在溶骨性病变中的生存，并通过通过小窝传递信号直接刺激转移，以及通过使中央趋化因子SDF-1失活而间接通过减少骨髓瘤细胞的滞留来促进转移。在具体目标3中，我们将确定增加成骨细胞活性和抑制DASH蛋白水解酶活性的联合治疗在控制MM的生长和扩散以及防止复发方面是否比任何一种单独治疗方法更有效。通过与所有项目和核心的互动，使用我们的SCID-HU模型以及与原代样本和骨髓瘤细胞株的共培养系统，我们将揭示与骨合成代谢相关的因子的抗肿瘤和抗转移作用，以及使用得失方法、特定的抑制剂和重组蛋白揭示多发性骨髓瘤中DASH蛋白酶的分子机制。

The common and typical induction of osteolytic bone disease in multiple myeloma (MM) led to the notion that bone disease is both a consequence and a necessity of MM progression and metastasis. Our reported and preliminary data suggest that osteoclasts support myeloma cell survival and metastasis through production of certain serine proteases known as dipeptidyl peptidase-IV activity and/or structure homolog (DASH) proteins and that inhibiting activity of osteoclasts or DASH proteases suppresses growth of medullary MM. Conversely, we found that osteoblasts reduce growth of myeloma cells through production of certain small leucine-rich proteoglycans and that increased osteoblast activity in myelomatous bones (from treating with osteoblast-activating agents [parathyroid hormone or anti-DKKI] or with cytotherapy [osteoprogenitor cells]) increases bone formation, creating an inhospitable microenvironment that attenuates MM progression in vivo. Based on these findings, we hypothesize that the microenvironment in existing focal lesions is a critical determinant of long-term survival and dissemination of myeloma cells; therefore, simultaneously inhibiting osteoclast activity and stimulating bone formation is critical for sustaining a patient's response to treatment and for preventing metastasis. In Specific Aim 1, we will determine whether increased bone formation by bone-anabolic agents (e.g., PTH, anti-DKKI), with or without exogenous osteoblast precursors, will sustain remission induced by clinical agents (e.g., melphalan, dexamethasone, bortezomib, lenalidomide), and/or prevent tumor metastasis upon relapse. We will also investigate molecular mechanisms associated with these effects. In Specific Aim 2, we will determine whether osteoclast-produced DASH proteases contribute to MM-induced bone disease, support survival of MM in osteolytic lesions, and stimulate metastasis directly by signaling through caveolae and indirectly through reduced retention of myeloma cells by inactivating the central chemokine SDF-1. In Specific Aim 3, we will determine whether combining treatments to increase activity of osteoblasts and inhibit activity of DASH proteases has superior effects on controlling MM growth and dissemination and on preventing relapse than either individual therapeutic approach. Through interactions with all projects and cores, using our SCID-hu model and coculture systems with primary samples and myeloma cell lines, we will unravel antitumor and antimetastatic effects of factors associated with bone anabolism, as well as molecular mechanisms of DASH proteases in MM using gain-and-loss approaches, specific inhibitors, and recombinant proteins.