Role of CCL25-CCR9 in Prostate Cancer

描述(申请人提供)：尽管最近前列腺癌(PCA)治疗的临床药物库中增加了激素难治性转移疾病，但绝大多数(~90%)前列腺癌患者死于骨转移，尤其是骨骼转移。目前治疗前列腺癌的大多数化疗方案，包括多西他赛，基本上都是非选择性地针对快速分裂的细胞群体，因此呈现出衰弱的毒性。其他主要的限制是由于雄激素非依赖性的出现以及转移性疾病的低增殖能力。因此，识别由增殖较少的， 雄激素非依赖性转移性前列腺癌细胞可能导致这种可怕的疾病几乎完全消除。人们越来越认识到，趋化因子-配体轴在肿瘤细胞的转移和器官特异性转移的发展中起着至关重要的作用。本实验室首次发现CC趋化因子受体9(CCR9)在前列腺癌中选择性过度表达，而在正常前列腺上皮中几乎不表达。我们最近发表的初步数据表明：1)CCR9在PCa细胞中高表达，并在体外介导PCa细胞的迁移、侵袭和存活；2)CCR9在临床前列腺癌组织中也高表达；3)CCR9的天然配体CCL25在PCa临床标本中以旁分泌的方式表达，在PCa患者血清中也表达上调；4)与非肿瘤小鼠相比，荷瘤小鼠的骨髓基质细胞显著产生CCL25；5)抑制CCR9-CCL25轴使PCa细胞对化疗的反应变得敏感。基于这些令人鼓舞的数据，我们假设CCR9-CCL25轴在前列腺癌转移中起关键作用，是癌症选择性治疗的靶点。以此为靶点将有助于开发新的化疗策略，并通过使前列腺癌细胞对现有方案敏感来改进现有的化疗策略。为了验证我们的假设，我们建议确定CCR9-CCL25轴在(I)诱导前列腺癌细胞迁移和侵袭，(Ii)前列腺癌细胞存活和凋亡，(Iii)触发前列腺癌生长和转移，iv)增强临床方案的化疗疗效中所起的作用。为了实现我们的目标，我们建立了CCR9条件敲除细胞，用于体外实验，以确定其在PCa细胞迁移、侵袭和存活中的作用，并确定其在肿瘤生长、转移和多西紫杉醇治疗效果中的潜在作用。此外，针对CCR9驱动的信号分子的siRNA双链或特定的药物抑制剂将被用来评估CCR9-CCL25轴在促进转移中的作用。我们乐观地认为，这些研究的成功完成将确定这种新发现的趋化因子在前列腺癌中的作用，并将 对提高我们对趋化因子在调节疾病侵袭性中的理解有很大的帮助。此外，它还将使针对CCR9-CCL25轴的PCa合理疗法的设计和开发成为可能。

DESCRIPTION (provided by applicant): Despite recent additions in the clinical armamentarium of drugs for prostate cancer (PCa) therapy, hormone refractory metastatic disease accounts for an overwhelming majority (~90%) of PCa deaths with skeletal metastases, particularly in bones. Most currently-available chemotherapeutic regimens for PCa including docetaxel essentially target rapidly dividing cell populations non-selectively, thus presenting debilitating toxicities. Other major limitations are owing to the emergence of androgen-independence as well as lower proliferative capacity of the metastatic disease. Thus, identification of novel molecular targets that are selectively presented by the less-proliferative, androgen-independent metastatic prostate cancer cells might result in the near-complete elimination of this dreaded disease. It is becoming well appreciated that the chemokine-ligand axis is crucially involved in tumor cell trafficking and the development of organ-specific metastases. Our laboratory is the first to show that CC chemokine receptor 9 (CCR9) is selectively over expressed in prostate cancers with negligible expression in normal prostate epithelia. Our recently published and preliminary data demonstrate that 1) CCR9 is highly expressed by PCa cells and mediates PCa cell migration, invasion and survival in vitro, 2) CCR9 is also highly expressed in clinical prostate cancer tissue samples, 3) CCL25, a natural ligand of CCR9, is expressed in a paracrine manner by PCa clinical sample and also elevated in PCa patient serum, 4) bone marrow stromal cells of tumor-bearing mice significantly produce CCL25, compared to non-tumor bearing ones, 5) inhibition of CCR9-CCL25 axis sensitizes cellular responses to chemotherapy in PCa cells. Based upon these encouraging data, we hypothesize that CCR9-CCL25 axis plays a crucial role in prostate cancer metastasis and is a cancer-selective therapeutic target. Targeting this axis will enable development of new chemotherapeutic strategies as well as improving existing ones by sensitizing prostate cancer cells to currently available regimens. To validate our hypothesis, we propose to determine the role of CCR9-CCL25 axis in (i) inducing prostate cancer cell migration and invasion, (ii) prostate cancer cell survival and apoptosis, (iii) triggering prostate cancer growth and metastases iv) enhancing chemotherapeutic efficacy of clinical regimens. To accomplish our aims, we have generated CCR9 conditional knockout cells that will be used for in vitro assays to determine its role in PCa cell migration, invasion and survival, and determining its potential role in tumor growth, metastasis and therapeutic efficacy of docetaxel. In addition, siRNA duplexes or specific pharmacological inhibitors against CCR9 driven signaling molecules will be used to evaluate the role of CCR9-CCL25 axis in promotion of metastases. We are optimistic that the successful completion of these studies will define the role of this newly identified chemokine in PCa and will go a long way to enhance our understanding of chemokines in mediating disease aggressiveness. Furthermore, it will enable the design and development of rational therapies directed against the CCR9-CCL25 axis for PCa.