Zhao Yunshuo, Chen Xiaotong, Lyu Sifan, Ding Zhe, Wu Yahong, Gao Yanfeng, Du Jiangfeng
School of Life Sciences, Zhengzhou University, Zhengzhou, China.
Chem Biol Drug Des. 2021 Jul;98(1):192-205. doi: 10.1111/cbdd.13867. Epub 2021 Jun 3.
In the tumor microenvironment, inflammation and necrosis cause the accumulations of ATP extracellularly, and high concentrations of ATP can activate P2X7 receptors (P2X7R), which leads to the influx of Na , K , or Ca into cells and trigger the downstream signaling pathways. P2X7R is a relatively unique ligand-gated ion channel, which is over-expressed in most tumor cells. The activated P2X7R facilitates the tumor growth, invasion, and metastasis. Inhibition of the P2X7R activation can be applied as a potential anti-tumor therapy strategy. There are currently no anti-tumor agents against P2X7R, though several P2X7R antagonists for indications such as anti-inflammatory and anti-depression were reported. In this study, we combined homology modeling (HM), virtual screening, and EB intake assay to characterize the structural features of P2X7R and identify several novel antagonists, which were chemically different from any other known P2X7R antagonists. The identified antagonists could effectively prevent the pore opening of P2X7R with IC50 values ranging from 29.14 to 35.34 μM. HM model showed the area between ATP-binding pocket, and allosteric sides were hydrophobic and suitable for small molecule interaction. Molecular docking indicated a universal binding mode, of which residues R294 and K311 were used as hydrogen bond donors to participate in antagonist interactions. The binding mode can potentially be utilized for inhibitor optimization for increased affinity, and the identified antagonists can be further tested for anti-cancer activity or may serve as chemical agents to study P2X7R related functions.
在肿瘤微环境中，炎症和坏死导致细胞外ATP积累，高浓度的ATP可激活P2X7受体（P2X7R），从而导致Na⁺、K⁺或Ca²⁺流入细胞并触发下游信号通路。P2X7R是一种相对独特的配体门控离子通道，在大多数肿瘤细胞中过度表达。激活的P2X7R促进肿瘤生长、侵袭和转移。抑制P2X7R激活可作为一种潜在的抗肿瘤治疗策略。目前尚无针对P2X7R的抗肿瘤药物，尽管有报道称几种P2X7R拮抗剂可用于抗炎和抗抑郁等适应症。在本研究中，我们结合同源建模（HM）、虚拟筛选和EB摄取试验来表征P2X7R的结构特征，并鉴定了几种新型拮抗剂，它们在化学结构上与任何其他已知的P2X7R拮抗剂不同。所鉴定的拮抗剂能够有效阻止P2X7R的孔开放，IC50值范围为29.14至35.34μM。HM模型显示，ATP结合口袋与变构位点之间的区域是疏水的，适合小分子相互作用。分子对接表明存在一种通用的结合模式，其中残基R294和K311作为氢键供体参与拮抗剂相互作用。这种结合模式可能用于优化抑制剂以提高亲和力，所鉴定的拮抗剂可进一步测试其抗癌活性，或可作为研究P2X7R相关功能的化学试剂。
