Hosoya Takahiro, Arai Midori A, Koyano Takashi, Kowithayakorn Thaworn, Ishibashi Masami
Graduate School of Pharmaceutical Sciences, Chiba University, Chiba 263-8522, Japan.
Chembiochem. 2008 May 5;9(7):1082-92. doi: 10.1002/cbic.200700511.
The aberrant hedgehog (Hh)/GLI signaling pathway causes the formation and progression of a variety of tumors. To search for Hh/GLI inhibitors, we screened for naturally occurring inhibitors of the transcriptional activator GLI1 by using a cell-based assay. We identified zerumbone (1), zerumbone epoxide (2), staurosporinone (9), 6-hydroxystaurosporinone (10), arcyriaflavin C (11) and 5,6-dihydroxyarcyriaflavin A (12) as inhibitors of GLI-mediated transcription. In addition, we isolated physalins F (17) and B (18) from Physalis minima, which are also potent inhibitors. These compounds also inhibited GLI2-mediated transactivation. Semiquantitative RT-PCR and Western blotting analysis further revealed that 1, 9, 17, and 18 decreased Hh-related component expressions. We also show that inhibitors of GLI-mediated transactivation reduce the level of the antiapoptosis Bcl2 expression. Finally, these identified compounds were cytotoxic to PANC1 pancreatic cancer cells, which express Hh/GLI components. These results strongly suggest that the cytotoxicity of the compounds to PANC1 cells correlates with their inhibition of GLI-mediated transcription.
异常的刺猬信号通路（Hh）/GLI信号通路会导致多种肿瘤的形成和进展。为了寻找Hh/GLI抑制剂，我们通过基于细胞的检测方法筛选了转录激活因子GLI1的天然抑制剂。我们鉴定出莪术二酮（1）、莪术环氧酮（2）、星形孢菌素酮（9）、6-羟基星形孢菌素酮（10）、刺黄素C（11）和5,6-二羟基刺黄素A（12）为GLI介导转录的抑制剂。此外，我们从酸浆中分离出酸浆苦素F（17）和酸浆苦素B（18），它们也是有效的抑制剂。这些化合物还抑制了GLI2介导的反式激活。半定量RT-PCR和蛋白质印迹分析进一步表明，1、9、17和18降低了Hh相关成分的表达。我们还表明，GLI介导的反式激活抑制剂降低了抗凋亡蛋白Bcl2的表达水平。最后，这些鉴定出的化合物对表达Hh/GLI成分的PANC1胰腺癌细胞具有细胞毒性。这些结果强烈表明，这些化合物对PANC1细胞的细胞毒性与其对GLI介导转录的抑制作用相关。
