Platelets promote growth of ovarian cancer

描述（由申请人提供）：血小板计数升高是许多癌症患者的常见结果，包括卵巢癌患者。卵巢癌合并血小板增多症的患者与癌症分期相似且血小板计数正常的患者相比，预后更差。我们已经证明，血小板促进癌细胞在体外和小鼠卵巢癌模型中的增殖;减少血小板计数减少卵巢癌细胞诱导的小鼠原位肿瘤的大小。为了确定血小板对癌细胞的生长促进作用的机制，我们在体外使用针对血小板的阻断剂，并且发现血小板活化和TGF？1的释放对于血小板对癌细胞的增殖作用是重要的。在这个项目中，我们将研究血小板和癌细胞之间的相互作用在体内，使用卵巢癌的小鼠模型和卵巢癌患者的组织样本。我们的假设是，血小板和癌细胞之间存在反馈回路。癌细胞分泌ADP并激活血小板，血小板分泌促进癌细胞增殖的TGF ² 1。在具体 目的1，我们将使用转基因小鼠或药理学试剂研究阻断血小板上的ADP受体是否会破坏血小板对小鼠原位肿瘤的生长促进作用。在具体目标2中，我们将靶向血小板的TGF <$1分泌、癌细胞上的TGF <$1受体或TGF <$1受体信号传导，以评估TGF <$1在血小板-癌细胞相互作用中的作用。我们将使用血小板特异性TGF β 1缺陷小鼠、抑制剂RNA或针对TGF β受体信号传导的药理学试剂来进行这些实验。为了在肿瘤内发生血小板和癌细胞之间的相互作用，血小板应该退出循环并进入肿瘤微环境。我们已经证明了在小鼠体内植入的肿瘤内的血管外存在血小板。在具体目标3中，我们将使用免疫荧光和电子显微镜对人和小鼠卵巢癌组织样本研究血小板从肿瘤微循环中退出的机制。我们将确定血小板外渗的途径，并评估血小板对中性粒细胞外渗的依赖性。本研究的目的是评估使用抗血小板药物作为有效抗癌治疗的可能性。

DESCRIPTION (provided by applicant): Elevated platelet counts are a common finding in many cancer patients, including patients with ovarian cancer. Patients with ovarian cancer and thrombocytosis have a worse prognosis compared to patients with similar stages of cancer and normal platelet counts. We have shown that platelets promote proliferation of cancer cells both in vitro and in the murine models of ovarian cancer; and reducing platelet counts decreased the size of orthotopic tumor induced in mice by ovarian cancer cells. To identify the mechanisms of the growth- enhancing effect of platelets on cancer cells, we used blocking reagents against platelets in vitro, and found that platelet activation and release of TGF¿1 are important for the proliferative effect of platelets on cancer cells. In this project, we will study the interaction between platelets and cancer cells in vivo, using both murine models of ovarian cancer and tissue samples obtained from patients with ovarian cancer. Our hypothesis is that there is a feedback loop between platelets and cancer cells. Cancer cells secrete ADP and activate platelets, and platelets secrete TGF¿1 that promotes proliferation in cancer cells. In the specific aim 1, we will investigate whether blocking ADP receptors on platelets would disrupt the growth promoting effect of platelets on orthotopic tumors in mice, using genetically modified mice or pharmacologic reagents. In the specific aim 2, we will target TGF¿1 secretion from platelets, TGF¿1 receptor on cancer cells, or TGF¿1 receptor signaling to evaluate the role of TGF¿1 on the platelet-cancer cell interaction. We will use platelet-specific TGF¿1 deficient mice, inhibitor RNAs, or pharmacologic reagents against TGF¿ receptor signaling to conduct these experiments. For the interaction between platelets and cancer cells to occur inside the tumors, platelets should exit circulation and enter into tumor microenvironment. We have shown the presence of platelets outside of blood vessel inside the implanted tumors in mice. In the specific aim 3, we will study the mechanisms of platelet exit from tumor microcirculation using immunofluorescence and electron microscopy on human and murine ovarian cancer tissue samples. We will identify the route of platelet extravasation, and evaluate the dependency of platelets on neutrophils for extravasation. The goal of our studies in this grant proposal is to evaluate the possibility of using anti-platelet reagents as an effective anticancer therapy.