Zuo Yi, Zhang Chao-Zheng, Ren Qing, Chen Yao, Li Xiao, Yang Ji-Rui, Li Hong-Xiang, Tang Wen-Tao, Ho Hing-Man, Sun Chen, Li Mei-Mei, Ren Bo, Deng Yun, Wang Mao-Lin, Lu Jun
State Key Laboratory of Southwestern Chinese Medicine Resources, School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu, 611137, China.
School of Chinese Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, 999077, China.
Phytomedicine. 2022 May;99:154015. doi: 10.1016/j.phymed.2022.154015. Epub 2022 Mar 3.
Breast cancer is one of the malignant tumors with the highest morbidity and mortality rate. Numerous efficient anti-breast cancer drugs are being derived from the development of natural products. Voacamine (VOA), a bisindole alkaloid isolated from Voacanga africana Stapf, possesses various pharmacological and biological activities.
In this study, we investigated the efficacy of VOA against breast cancer cells and elucidated the underlying mechanisms in vitro and in vivo.
Human breast cancer cell line MCF-7 and mouse breast cancer cell line 4T1 were used to study the underlying anti-cancer mechanisms of VOA. The proliferation was detected by MTT, colony formation, cell proliferation and wound-healing migration assays. Flow cytometry was utilized to determine the level of reactive oxygen species (ROS) cell-cycle, apoptosis and mitochondrial membrane potential. The target proteins were analyzed by Western blot. Molecular docking was performed and scored by AutoDock. Subcutaneous cancer models in mice were established to evaluate the anticancer effects in vivo.
Our results demonstrated that VOA selectively suppressed breast cancer MCF-7 and 4T1 cells proliferation with IC values of 0.99 and 1.48 μM, and significantly inhibited the migration and colony formation of tumor cells. Furthermore, the cell cycle was arrested in the S phase with the decreased expression levels of CDK2, Cyclin A and Cyclin E. Additionally, exposure to VOA dose-dependently brought about dose-dependently the loss of mitochondrial membrane potential (Δψ) and amassment of reactive oxygen species (ROS), resulting in the initiation of the intrinsic apoptotic pathway. Western blot analysis unveiled that VOA significantly activated mitochondrial-associated apoptosis and obviously suppress the PI3K/Akt/mTOR pathway via modulation of related protein expression levels in both tumor cell lines. In tumor-bearing mouse models, administration of VOA dose-dependently inhibited the tumor growth without causing apparent toxicities.
These findings revealed the novel properties of VOA in promoting apoptosis of breast cancer cells by activating mitochondrial-associated apoptosis signaling pathway and inhibiting PI3K/Akt/mTOR signaling pathway and significantly decreasing tumor size without detecting appreciable toxicity. In summary, the present results demonstrated VOA could be an encouraging drug candidate to cure breast cancer, exhibiting an effective method to exploit unique drugs from natural components.
乳腺癌是发病率和死亡率最高的恶性肿瘤之一。众多高效的抗乳腺癌药物正从天然产物的研发中衍生出来。沃卡明（VOA）是从非洲沃卡木中分离得到的一种双吲哚生物碱，具有多种药理和生物学活性。
在本研究中，我们研究了VOA对乳腺癌细胞的疗效，并阐明了其在体外和体内的潜在作用机制。
使用人乳腺癌细胞系MCF-7和小鼠乳腺癌细胞系4T1来研究VOA的潜在抗癌机制。通过MTT、集落形成、细胞增殖和伤口愈合迁移试验检测细胞增殖。利用流式细胞术测定活性氧（ROS）水平、细胞周期、细胞凋亡和线粒体膜电位。通过蛋白质印迹法分析靶蛋白。使用AutoDock进行分子对接并评分。建立小鼠皮下癌模型以评估体内抗癌效果。
我们的结果表明，VOA选择性抑制乳腺癌MCF-7和4T1细胞增殖，IC值分别为0.99和1.48 μM，并显著抑制肿瘤细胞的迁移和集落形成。此外，细胞周期停滞在S期，CDK2、细胞周期蛋白A和细胞周期蛋白E的表达水平降低。此外，暴露于VOA会剂量依赖性地导致线粒体膜电位（Δψ）丧失和活性氧（ROS）积累，从而引发内源性凋亡途径。蛋白质印迹分析表明，VOA显著激活线粒体相关凋亡，并通过调节两种肿瘤细胞系中相关蛋白的表达水平明显抑制PI3K/Akt/mTOR途径。在荷瘤小鼠模型中，给予VOA剂量依赖性地抑制肿瘤生长，且未引起明显毒性。
这些发现揭示了VOA通过激活线粒体相关凋亡信号通路和抑制PI3K/Akt/mTOR信号通路促进乳腺癌细胞凋亡的新特性，并显著减小肿瘤大小，且未检测到明显毒性。总之，目前的结果表明VOA可能是一种治疗乳腺癌的有前景的候选药物，展示了从天然成分中开发独特药物的有效方法。
