Inhibitors of Hedgehog Signaling For Brain Cancer Chemotherapy

该研究计划的总体目标是开发用于治疗脑癌的新化疗药物。在美国，每年诊断出大约10，000例胶质瘤，其中只有大约一半的患者存活一年。对于成人，高级别胶质瘤或多形性胶质母细胞瘤（GBM）是最恶性和侵袭性的脑肿瘤。治疗方法包括手术、放疗和化疗，但确诊后生存期很少超过一年。因此，迫切需要新的分子靶点和临床干预方法来提高生存率并减少副作用。多形性胶质母细胞瘤（GBM）需要Sonic Hedgehog（SHH）信号传导用于其生长。我们的假设是，阻断SHH信号转导是脑癌化疗的一个有前途的策略。环巴胺是一种天然存在的生物碱，可抑制SHH通路，在体内通过激活SHH信号减少肿瘤生长，并已显示可穿过血脑屏障。然而，环巴胺的代谢不稳定性排除了其作为化疗剂的用途。我们建议，结构简化，代谢稳定的环巴胺样SHH信号传导抑制剂可以从市售的甾体前体（雌甾烷，雄甾烷和胆甾烷）。甾体框架使得能够容易地合成用于体外生物学测试和用于优化生物学效力和选择性的类似物。重要的是，我们的初步结果已经确定了这种情况的有效性。因此，本文概述的研究有望开发癌症生物学中的重要新工具和治疗脑癌的新候选药物。

The overarching goal of this research program is the development of new chemotherapeutic agents for the treatment of brain cancer. Approximately 10,000 cases of glioma are diagnosed each year in the United States and only about half of those patients survive one year. For adults, high-grade glioma or glioblastoma multiforme (GBM) is the most malignant and invasive brain tumor. Treatments include surgery, radiotherapy, and chemotherapy, yet survival rarely exceeds one year after diagnosis. New molecular targets and approaches for clinical intervention are thus desperately needed to increase the survival rate and reduce side effects. Glioblastoma multiforme (GBM) requires Sonic Hedgehog (SHH) signaling for its growth. Our hypothesis is that blockade of SHH signaling constitutes a promising strategy for brain cancer chemotherapy. Cyclopamine, a naturally occurring alkaloid that inhibits the SHH pathway, reduces growth of tumors with activated SHH signaling in vivo, and has been shown to cross the blood brain barrier. However, the metabolic instability of cyclopamine precludes its use as a chemotherapeutic agent. We propose that structurally simplified, metabolically stable cyclopamine-like SHH signaling inhibitors can be prepared from commercially available steroidal precursors (estranes, androstanes and cholanes). The steroidal framework enables the facile synthesis of analogs for in vitro biological testing and for the optimization of biological potency and selectivity. Importantly, our preliminary results have established the validity of this scenario. The studies outlined herein therefore hold the promise of developing important new tools in cancer biology and new drug candidates for the treatment of brain cancers.