Testing of Novel Apoptotic Agents in Prostate Cancer

这项R21提案旨在测试一系列新型凋亡诱导剂的体内抗肿瘤活性，作为我们开发抗前列腺癌新治疗药物的努力的一部分。基于我们对环氧合酶-2(COX-2)抑制剂塞来昔布的研究，我们合成了一系列高效诱导前列腺癌细胞凋亡的衍生物，而对正常前列腺上皮细胞没有不良影响。我们的数据表明，这些凋亡剂通过与传统抗癌药截然不同的机制触发细胞死亡。首先，这些分子下调对细胞生存至关重要的多个信号通路，包括Akt和ERK2介导的那些信号通路。其次，它们通过阻断内质网(ER)Cat+-ATPase来刺激细胞内钙离子的增加，这一机制让人想起thapsigargin。考虑到钙离子在诱导雄激素非依赖性前列腺癌细胞凋亡中的关键作用，这种钙离子扰动效应值得注意。此外，这些分子引发的细胞凋亡与雄激素反应和晚期前列腺癌相关的遗传损伤无关。因此，这些凋亡诱导剂有可能被开发成阻止前列腺癌进展或治疗转移性前列腺癌的化疗药物。体内效应将由一组前列腺癌细胞株使用两种动物模型进行评估，这两种动物模型构成了这项提案的两个具体目标。第一个特定的目标将是检查体内对裸鼠移植瘤的凋亡活性。人前列腺癌细胞将被注射到无瘤雄性裸鼠(波罗的海，nu/nu)的皮下。测试化合物的抗肿瘤活性是通过与阿霉素治疗组和赋形剂治疗对照组相比，通过防止肿瘤形成或延缓肿瘤生长来评估的。第二个具体目标将是在肾被膜下肿瘤模型中检测体内的细胞凋亡活性。将人前列腺癌组织片段植入免疫活性小鼠的肾被膜下，以评估其对试验药物的化疗敏感性。肾被膜下间隙是输送营养物质和药物的理想场所，提供丰富的血管床，便于原位观察异种移植物。总之，这些动物模型研究将验证这些化合物的体外诱导凋亡作用与体内肿瘤生长抑制相关。

This R21 proposal is aimed at testing the in vivo anti-tumor activity of a series of novel apoptosis-inducing agents as part of our effort to develop new therapeutic agents against prostate cancer. Based on our study on the cyclooxygenase-2 (COX-2) inhibitor celecoxib, we have generated a series of derivatives that display high potency in eliciting apoptotic death in prostate cancer cells, while exerting no adverse effect on normal prostate epithelial cells. Our data indicate that these apoptotic agents trigger cell death via mechanisms distinctly different from that of conventional anti-cancer agents. First, these molecules down-regulate multiple signaling pathways essential to cell survival, including those mediated by Akt and ERK2. Second, they stimulate intracellular Ca2+ increase by blocking endoplasmic reticulum (ER) Cat+-ATPases, a mechanism reminiscent of thapsigargin. This Ca2+ perturbing effect is noteworthy considering the crucial role of Ca2+ in the induction of apoptosis in androgen-independent prostate cancer cells. Moreover, the triggering of apoptosis by these molecules is independent of androgen responsiveness and genetic lesions associated with advanced prostate cancer. Consequently, these apoptosis-inducing agents have translational potential to be developed into chemotherapeutic agents to stop prostate cancer progression or to treat metastatic prostate cancer. The in vivo effect will be evaluated with a panel of prostate cancer cell lines using two animal models that constitute the two specific aims of this proposal. The first specific aim will be to examine the apoptotic activity in vivo against xenograft tumors in nude mice. Human prostate cancer cells will be injected into the subcutaneous space of athymic male nude mice (Baltic, nu/nu). Anti-tumor activity of the test compounds is assessed by the prevention of tumor formation or by the delay in tumor growth of the treated group with respect to the doxorubicin-treated and vehicle-treated control groups. The second specific aim will be to examine the apoptotic activity in vivo in the subrenal capsule tumor model. Human prostate adenocarcinoma tissue fragments are implanted under the renal capsule of immunocompetent mice to assess the chemosensitivity to the test agents. The subrenal capsular space represents an ideal site for the delivery of nutrients and drugs, provides a rich vascular bed, and permits easy visualization of the xenografts, in situ. Together, these animal-- model studies will validate that the in vitro apoptosis-inducing effect of these compounds is relevant for tumor growth inhibition in vivo.