Connexin hemichannels in suppression of breast cancer bone metastasis

连接蛋白半通道抑制乳腺癌骨转移

• 批准号: 9030104
• 负责人: Jean X Jiang
• 金额: $ 35.59万
• 依托单位: UNIVERSITY OF TEXAS HLTH SCIENCE CENTER
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-02-01 至 2021-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9030104
• 关键词: ATP Receptors; Adverse effects; Anchorage-Independent Growth; Attenuated; Biochemical; Biological Assay; Biology; Blocking Antibodies; Bone Diseases; Breast Cancer Cell; Breast Cancer Treatment; Cancer Etiology; Cell physiology; Cells; Clinical; Collaborations; Complication; Connexin 43; Connexins; Data; Defense Mechanisms; Development; Disseminated Malignant Neoplasm; Down-Regulation; Drug Targeting; Genes; Goals; Growth; Housing; Human; Imaging Techniques; In Vitro; Intervention; Knockout Mice; Laboratories; Malignant Neoplasms; Mechanical Stimulation; Mechanics; Mediator of activation protein; Metastatic Neoplasm to the Bone; Metastatic breast cancer; Microtubule Stabilization; Microtubules; Modality; Modeling; Mus; Neoplasm Metastasis; Osteoblasts; Osteoclasts; Osteocytes; Outcome; Patients; Pharmaceutical Preparations; Physical Exercise; Physical activity; Play; Purinoceptor; Receptor Signaling; Research; Research Activity; Role; Sampling; Site; Specimen; Structure; Testing; The Sun; Time; Tissues; base; bisphosphonate; bone; bone cell; bone strength; calmodulin-dependent protein kinase II; cancer cell; cell type; experience; in vivo; knock-down; malignant breast neoplasm; migration; mouse model; new therapeutic target; novel; optical imaging; paracrine; public health relevance; receptor; receptor-mediated signaling; release factor; shear stress; stathmin; targeted biomarker; tibia; tumor

 DESCRIPTION (provided by applicant): Bone is a major site for the preferential metastasis by advanced breast cancers. Bone metastases by breast cancers cause deadly complications and there is an unmet need for efficacious intervention with minimal side effect. The majority of previous studies have primarily focused on metastasized cancer cells or tumor supporting bone microenvironments. Here we propose to investigate the intrinsic anti-cancer metastatic potentials of the osteocytes, the most abundant bone cell type in the bone. Connexin (Cx) 43 hemichannels are richly present in osteocytes. Our preliminary study showed that the opening of Cx43 hemichannels by either bisphosphonate drugs or mechanical stimulation inhibited migration and anchorage-independent growth of breast cancer cells. Moreover, breast cancer bone metastasis appears to be augmented in osteocyte-specific Cx43 knockout mice when compared to wild-type controls. As such, we hypothesize that active Cx43 hemichannels in osteocytes release ATP and ATP acting in a paracrine manner activates purinergic receptor signaling in breast cancer cells, leading to the suppression of breast cancer bone metastasis. The goal is to establish the importance of osteocytic Cx43 hemichannels as a potential, novel drug target for the treatment. In this proposal, first, we will test the hypothesis that active osteocytic Cx43 hemichannels inhibit breast cancer cell metastasis. The effect of Cx43 hemichannel inhibition on breast cancer bone metastasis will be examined in vivo using in-house developed Cx43-deficient mouse models and hemichannel-specific blocking antibodies. The cell-based studies will be used to dissect the effect of osteocytic Cx43 hemichannels on various subtypes of breast cancer cells. Second, we will test the hypothesis that osteocytic Cx43 hemichannels activated by mechanical loading, associated with physical exercise, plays a critical role in the inhibition of breast cancer bone metastasis. We will apply mechanical loading through flow shear stress in vitro and tibial loading in vivo to assess the functional involvement of osteocytic Cx43-hemichannels in breast cancer migration and bone metastasis, and on bone cell function and bone strength, as the latter could serve as a complementary defense mechanism against bone metastasis. Third, we will test the hypothesis that P2X7 receptor in breast cancer cells activated by ATP released by osteocytic Cx43 hemichannels is responsible for the suppression of bone metastasis by first investigating the roles of ATP and P2X7 purinergic receptor, and followed by studying the underlying mechanism concerning how the activation of P2X7 receptor-mediated signaling inhibits breast cancer cell function and if down-regulation of this mechanism is more prevalent in clinical samples associated with bone metastases. Through a unique collaboration with the laboratories of the two PIs with their strong, complementary expertise, the proposed studies are expected to reveal a novel, inhibitory mechanism in the suppression of breast cancer bone metastasis, and should make significant contributions to the discovery of new therapeutic targets for the treatment of breast cancer-induced bone metastases.

 描述（由申请人提供）：骨是晚期乳腺癌优先转移的主要部位。乳腺癌的骨转移导致致命的并发症，并且存在对具有最小副作用的有效干预的未满足的需求。以前的大多数研究主要集中在转移的癌细胞或肿瘤支持骨微环境。在这里，我们建议调查骨细胞，骨中最丰富的骨细胞类型的内在抗癌转移潜力。连接蛋白（Cx）43半通道在骨细胞中丰富存在。我们的初步研究表明，无论是双膦酸盐药物或机械刺激Cx43半通道的开放抑制乳腺癌细胞的迁移和锚定非依赖性生长。此外，与野生型对照组相比，骨细胞特异性Cx43基因敲除小鼠的乳腺癌骨转移似乎有所增加。因此，我们假设骨细胞中的活性Cx43半通道释放ATP，并且ATP以旁分泌方式激活乳腺癌细胞中的嘌呤能受体信号传导，从而抑制乳腺癌骨转移。目的是确定骨细胞Cx43半通道作为治疗的潜在新药物靶点的重要性。在这个建议中，首先，我们将测试的假设，活性骨细胞Cx43半通道抑制乳腺癌细胞转移。将使用内部开发的Cx43缺陷小鼠模型和半通道特异性阻断抗体在体内检查Cx43半通道抑制对乳腺癌骨转移的影响。基于细胞的研究将用于解剖骨细胞Cx43半通道对各种亚型乳腺癌细胞的影响。其次，我们将测试的假设，骨细胞Cx43半通道激活的机械负荷，与体育锻炼，在乳腺癌骨转移的抑制中起着至关重要的作用。我们将通过体外流动剪切应力和体内胫骨载荷来施加机械载荷，以评估骨细胞Cx43-半通道在乳腺癌迁移和骨转移中的功能参与，以及骨细胞功能和骨强度，因为后者可以作为对抗骨转移的补充防御机制。第三，我们将通过首先研究ATP和P2 X7嘌呤能受体的作用来检验由骨细胞Cx43半通道释放的ATP激活的乳腺癌细胞中的P2 X7受体负责抑制骨转移的假设，随后研究了P2 X7受体介导的信号转导激活如何抑制乳腺癌细胞功能的潜在机制，这种机制的调节在与骨转移相关的临床样品中更为普遍。通过与两个PI实验室的独特合作，凭借其强大的互补专业知识，拟议的研究有望揭示抑制乳腺癌骨转移的新抑制机制，并应为发现治疗乳腺癌诱导的骨转移的新治疗靶点做出重大贡献。