Bone and Breast Cancer Molecular Interactions

 描述（由申请人提供）：没有治愈晚期乳腺癌的方法。乳腺癌具有非常高的骨转移倾向。由206块骨骼组成的巨大骨骼隔室允许增加癌症负担，进一步转移，复发，恶病质，最终死亡。此外，骨转移通常导致骨破坏、极度疼痛、骨折和瘫痪，导致生活质量差或死于相关并发症。乳腺癌细胞不仅产生破坏骨的细胞因子/趋化因子，而且还刺激骨祖细胞产生导致骨吸收的因子。尽管双膦酸盐和地舒单抗等治疗在一定程度上减少了骨骼事件，但患者仍然患有骨骼并发症， 药物副作用，如AVN或非典型骨折。我们计划建立新的基于机制的治疗策略，通过有效杀死骨中的乳腺癌并靶向其与骨细胞的溶骨性相互作用，减轻癌症负担，预防骨骼并发症，延长晚期乳腺癌伴大面积骨转移患者的生命。我们的建议源于临床观察。我们一直观察到磷酸化细胞外受体激酶（pERK）1/2在来自乳腺癌患者的病理性骨折手术标本和文献中广泛使用的良好建立的侵袭性人乳腺癌细胞系中的表达。ERK 1/2位于Ras-Raf-MEK 1的下游，在炎症和癌症等病理条件下被磷酸化。我们的初步数据揭示了pERK 1/2在骨破坏和癌细胞死亡的两个临床重要角度中的关键作用。首先，在裸鼠近端胫骨植入后，具有较高pERK 1/2的乳腺癌细胞（如MDA 231）比pERK 1/2低的乳腺癌细胞（如MCF-7）表现出更多的骨破坏。我们在RT-PCR细胞因子/趋化因子阵列上鉴定了一组受pERK 1/2信号特异性调节的促炎细胞因子/趋化因子。此外，乳腺癌细胞磷酸化ERK 1/2并触发与乳腺癌细胞共培养的成骨细胞中细胞因子/趋化因子的表达。其次，pERK 1/2靶向单独与AZD 6244（一种临床级MEK 1-pERK 1/2抑制剂）或与阿霉素联合使用会增加乳腺癌细胞的细胞死亡。我们的假设是，靶向MEK 1-pERK 1/2通过促进癌细胞死亡和阻断骨中促破骨细胞生成性炎症来提高乳腺癌患者的生存率。具体目标1（骨破坏机制）是确定pERK 1/2在侵袭性三阴性乳腺癌细胞和相互作用的成骨基质细胞中的促破骨细胞生成作用。具体目标2（癌细胞死亡的机制增强）是确定pERK 1/2在乳腺癌细胞存活和化学抗性中的作用。具体目标3（体内治疗翻译）是建立pERK 1/2靶向作为骨中侵袭性溶骨性转移性乳腺癌的有效分子辅助治疗。

 DESCRIPTION (provided by applicant): There are no means for curing advanced breast cancers. Breast cancer has a very high metastatic predisposition to bone. The immense skeletal compartments consisting of 206 bones allow for increasing cancer burden, further metastases, recurrence, cachexia, and eventually, death. In addition, bone metastasis often causes bone destruction, extreme pain, fractures, and paralysis, leading to poor quality of life or death from associated complications. Breast cancer cells not only produce bone-destroying cytokines/chemokines, but also stimulate osteoprogenitor cells to produce factors leading to osteoclastic bone resorption. Although treatments like bisphosphonates and denosumab decrease skeletal events to a certain degree, patients still suffer from skeletal complications and drug side effects such as AVN or atypical fractures. We plan to establish new mechanism-based therapeutic strategies that will reduce cancer burden, prevent skeletal complications, and prolong the life of patients with advanced breast cancers with massive skeletal metastases by effectively killing breast cancers in bone and targeting their osteolytic interactions with bone cells. Our proposal stems from clinical observations. We have consistently observed expression of phosphorylated Extracellular Receptor Kinase (pERK) 1/2 in pathological fracture surgical specimens from patients with breast cancers and well- established aggressive human breast cancer cell lines extensively used in literature. ERK1/2 is downstream of Ras-Raf-MEK1 and is phosphorylated in pathologic conditions such as inflammation and cancers. Our Preliminary Data shed light on a critical role of pERK1/2 in two clinically important angles of bone destruction and cancer cell death. First, breast cancer cells with higher pERK1/2, such as MDA231, cells exhibited more bone destruction than pERK1/2-low breast cancer cells such as MCF-7 following implantation in the proximal tibiae of nude mice. We identified a set of pro-inflammatory cytokines/chemokines that are specifically regulated by pERK1/2 signaling on RT-PCR cytokine/chemokine arrays. Furthermore, breast cancer cells phosphorylate ERK1/2 and trigger expression of cytokines/chemokines in osteoblasts that are co-cultured with breast cancer cells. Second, pERK1/2 targeting alone with AZD6244, a clinical-grade MEK1-pERK1/2 inhibitor, or in combination with doxorubicin increases cell death in breast cancer cells. Our hypothesis is that MEK1-pERK1/2 targeting prolongs the survival of breast cancer-bearing subjects by promoting cancer cell death and blocking pro-osteoclastogenic inflammation in bone. Specific Aim 1 (Mechanism of Bone Destruction) is to determine a pro-osteoclastogenic role of pERK1/2 in aggressive triple-negative breast cancer cells and interacting osteogenic stromal cells. Specific Aim 2 (Mechanistic Enhancement of Cancer Cell Death) is to determine a role of pERK1/2 in breast cancer cell survival and chemoresistance. Specific Aim 3 (Therapeutic Translation in vivo) is to establish pERK1/2 targeting as an effective molecular adjuvant therapy for aggressive osteolytic metastatic breast cancers in bone.