Li Jinhua, Yan Ziqi, Li Hongmei, Shi Qiong, Ahire Vidhula, Zhang Shenqiu, Nimishetti Naganna, Yang Dun, Allen Thaddeus D, Zhang Jing
Chengdu Anticancer Bioscience, Ltd., and J. Michael Bishop Institute of Cancer Research, Chengdu 610000, China.
Hospital of Chengdu University of Traditional Chinese Medicine, Chengdu 610000, China.
J Nat Prod. 2021 Aug 27;84(8):2312-2320. doi: 10.1021/acs.jnatprod.1c00429. Epub 2021 Aug 18.
To identify novel bioactive compounds, an image-based, cell culture screening of natural product extracts was conducted. Specifically, our screen was designed to identify phytochemicals that might phenocopy inhibition of the chromosomal passenger protein complex in eliciting mitotic and cytokinetic defects. A known alkaloid, scoulerine, was identified from the rhizomes of the plant as being able to elicit a transient mitotic arrest followed by either apoptosis induction or polyploidy. In examining the mitotic abnormality further, we observed that scoulerine could elicit supernumerary centrosomes during mitosis, but not earlier in the cell cycle. The localization of NUMA1 at spindle poles was also inhibited, suggesting diminished potential for microtubule recruitment and spindle-pole focusing. Polyploid cells emerged subsequent to cytokinetic failure. The concentration required for scoulerine to elicit all its cell division phenotypes was similar, and an examination of related compounds highlighted the requirement for proper positioning of a hydroxyl and a methoxy group about an aromatic ring for activity. Mechanistically, scoulerine inhibited AURKB activity at concentrations that elicited supernumerary centrosomes and polyploidy. AURKA was only inhibited at higher concentrations, so AURKB inhibition is the likely mechanism by which scoulerine elicited division defects. AURKB inhibition was never complete, so scoulerine may be a suboptimal AURK inhibitor or work upstream of the chromosomal passenger protein complex to reduce AURKB activity. Scoulerine inhibited the viability of a variety of human cancer cell lines. Collectively, these findings uncover a previously unknown activity of scoulerine that could facilitate targeting human cancers. Scoulerine, or a next-generation analogue, may be useful as a nontoxic component of combination therapies where inhibiting the chromosomal passenger protein complex is desired.
为了鉴定新型生物活性化合物，我们对天然产物提取物进行了基于图像的细胞培养筛选。具体而言，我们的筛选旨在鉴定可能模拟染色体乘客蛋白复合体抑制作用从而引发有丝分裂和胞质分裂缺陷的植物化学物质。从该植物的根茎中鉴定出一种已知生物碱——千金藤素，它能够引发短暂的有丝分裂停滞，随后诱导细胞凋亡或多倍体形成。在进一步研究有丝分裂异常时，我们观察到千金藤素在有丝分裂期间能够引发多余的中心体，但在细胞周期的早期阶段则不会。核有丝分裂器蛋白1（NUMA1）在纺锤体极的定位也受到抑制，这表明微管募集和纺锤体极聚焦的潜力降低。多倍体细胞在胞质分裂失败后出现。千金藤素引发其所有细胞分裂表型所需的浓度相似，对相关化合物的研究突出了芳香环上羟基和甲氧基的正确定位对活性的要求。从机制上讲，千金藤素在引发多余中心体和多倍体形成的浓度下抑制极光激酶B（AURKB）的活性。极光激酶A（AURKA）仅在较高浓度下受到抑制，因此AURKB抑制可能是千金藤素引发分裂缺陷的机制。AURKB抑制从未完全实现，因此千金藤素可能是一种次优的AURK抑制剂，或者在染色体乘客蛋白复合体的上游起作用以降低AURKB活性。千金藤素抑制多种人类癌细胞系的活力。总的来说，这些发现揭示了千金藤素以前未知的活性，这可能有助于靶向人类癌症。千金藤素或其下一代类似物可能作为联合疗法的无毒成分有用，在联合疗法中需要抑制染色体乘客蛋白复合体。
