Testing of Novel Apoptotic Agents in Prostate Cancer

这项R21提案旨在测试一系列新的细胞凋亡诱导药物的体内抗肿瘤活性，作为我们开发新的前列腺癌治疗药物的一部分。我们通过对环氧化酶-2 （COX-2）抑制剂塞来昔布的研究，生成了一系列衍生物，这些衍生物在诱导前列腺癌细胞凋亡死亡的同时，对正常前列腺上皮细胞无不良影响。我们的数据表明，这些凋亡药物通过与传统抗癌药物明显不同的机制触发细胞死亡。首先，这些分子下调对细胞存活至关重要的多种信号通路，包括Akt和ERK2介导的信号通路。其次，它们通过阻断内质网（ER） Cat+- atp酶来刺激细胞内Ca2+增加，这是一种让人想起信号素的机制。考虑到Ca2+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Ca2+干扰效应值得注意。此外，这些分子引发的细胞凋亡与雄激素反应性和晚期前列腺癌相关的遗传病变无关。因此，这些诱导细胞凋亡的药物具有转化潜力，可发展成为阻止前列腺癌进展或治疗转移性前列腺癌的化疗药物。体内效应将通过一组前列腺癌细胞系，使用两种动物模型来评估，这两种动物模型构成了本提案的两个具体目标。第一个特定的目的将是在裸鼠体内检测细胞凋亡对异种移植物肿瘤的活性。将人前列腺癌细胞注射到胸腺雄性裸鼠皮下间隙（Baltic, nu/nu）。测试化合物的抗肿瘤活性通过治疗组相对于阿霉素治疗组和载体治疗组的肿瘤形成的预防或肿瘤生长的延迟来评估。第二个具体目的是在肾下包膜肿瘤模型中检测细胞凋亡活性。将人前列腺癌组织片段植入免疫功能小鼠肾包膜下，评价其对试验药物的化学敏感性。肾包膜下空间为营养物质和药物的输送提供了理想的位置，提供了丰富的血管床，并且可以很容易地在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细胞凋亡诱导作用与体内肿瘤生长抑制有关。

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.