（图片来源：Courtesy of aphotofungi.com）
近日，来自美国埃默里大学温希普癌症研究所的研究人员在地衣和大黄中发现一种橙色色素可能具有抗肿瘤作用，未来或可将其作为抗肿瘤药物用于肿瘤治疗。相关研究结果发表在国际学术期刊Nature Cell Biology上。
蜈蚣苔素也叫做大黄素甲醚，用其处理从病人身上得到的白血病细胞，可减缓癌细胞生长并可将其杀死，同时对人类健康血细胞没有明显的毒性作用。除此之外，这种色素还能够抑制人类肺癌和头颈癌细胞系生长。
这支由华人科学家Jing Chen领导的研究团队在寻找代谢酶6PGD抑制剂的过程中发现了蜈蚣苔素的这些抗癌特性。6PGD是参与戊糖磷酸途径的一个重要代谢酶，研究人员之前已经发现6PGD的酶活性在一些类型的癌细胞中会出现增加。
在这项最新工作中，研究人员从急性淋巴细胞白血病病人体内获得了癌细胞，随后用蜈蚣苔素对其进行处理，同时也用相同剂量对健康血细胞进行处理，培养48小时之后，有一半的癌细胞被杀死，而相比之下健康血细胞没有受到损伤。随后研究人员又使用了另外一种叫做S3的更加强效的色素衍生物对植入小鼠体内的肺癌细胞系进行处理，结果表明肺癌细胞生长也会受到抑制。
研究人员表示，虽然他们的研究证实6PGD抑制剂没有表现出对健康细胞的毒性作用，但仍然需要更多的毒理学研究进行进一步验证。
目前蜈蚣苔素主要出现在一些天然食物色素中，还没有作为治疗药物得到人体检测。
6-Phosphogluconate dehydrogenase links oxidative PPP, lipogenesis and tumour growth by inhibiting LKB1-AMPK signalling
Ruiting Lin,Shannon Elf,Changliang Shan,Hee-Bum Kang,Quanjiang Ji,Lu Zhou,Taro Hitosugi,Liang Zhang,Shuai Zhang,Jae Ho Seo,Jianxin Xie,Meghan Tucker,Ting-Lei Gu,Jessica Sudderth,Lei Jiang,Matthew Mitsche,Ralph J. DeBerardinis,Shaoxiong Wu,Yuancheng Li,Hui Mao,Peng R. Chen,Dongsheng Wang,Georgia Zhuo Chen,Selwyn J. Hurwitz,Sagar Lonial,Martha L. Arellano,Hanna J. Khoury,Fadlo R. Khuri,Benjamin H. Lee,Qunying Lei,Daniel J. Brat,Keqiang Ye,Titus J. Boggon,Chuan He,Sumin Kang,Jun Fan & Jing Chen
The oxidative pentose phosphate pathway (PPP) contributes to tumour growth, but the precise contribution of 6-phosphogluconate dehydrogenase (6PGD), the third enzyme in this pathway, to tumorigenesis remains unclear. We found that suppression of 6PGD decreased lipogenesis and RNA biosynthesis and elevated ROS levels in cancer cells, attenuating cell proliferation and tumour growth. 6PGD-mediated production of ribulose-5-phosphate (Ru-5-P) inhibits AMPK activation by disrupting the active LKB1 complex, thereby activating acetyl-CoA carboxylase 1 and lipogenesis. Ru-5-P and NADPH are thought to be precursors in RNA biosynthesis and lipogenesis, respectively; thus, our findings provide an additional link between the oxidative PPP and lipogenesis through Ru-5-P-dependent inhibition of LKB1-AMPK signalling. Moreover, we identified and developed 6PGD inhibitors, physcion and its derivative S3, that effectively inhibited 6PGD, cancer cell proliferation and tumour growth in nude mice xenografts without obvious toxicity, suggesting that 6PGD could be an anticancer target.