Department of Clinical Pharmacology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200080, China.
Department of Clinical Pharmacology, Shanghai General Hospital of Nanjing Medical University, Shanghai 200080, China.
Phytomedicine. 2021 Jun;86:153553. doi: 10.1016/j.phymed.2021.153553. Epub 2021 Mar 23.
Colorectal cancer (CRC) is one of the most malignant tumors worldwide with poor prognosis and low survival rate. Since the clinical efficacy of the commonly used 5-fluorouracil (5-FU) based chemotherapy in CRC patients is limited because of its intolerable adverse effects, there is an urgent need to explore agents that can enhance the anti-cancer activity of 5-FU, reduce adverse effects and prevent resistance.
This study aims to investigate Tenacissoside G (TG)'s synergistic potentiation with 5-FU in inhibitory activity to colorectal cancer cells.
The anti-proliferation effect of TG on 5 colorectal cancer cell lines was assessed by CCK-8 assay. The isobologram analysis and combination index methods were used to detect the synergistic effect of TG and 5-FU by the CompuSyn software using the T.C. Chou Method. The effects of TG/5-FU combination on cell cycle distribution and apoptosis induction were detected by flow cytometry. DNA damage degrees of cells treated with TG, 5-FU and their combination were evaluated by the alkaline comet assay. Protein expression regulated by the TG/5-FU combination was investigated by western blotting. Furthermore, a xenograft mouse model was established to investigate the synergistic anti-tumor effect in vivo.
In this work, we observed a dose-dependent growth inhibitory activity and cell cycle arrest induction of TG, a monomeric substance originated from Marsdenia tenacissima (Roxb.) Wight et Arn, in colorectal cancer cells. It was found that TG potentiated the anticancer effects of 5-FU with a synergism for the first time. And the co-treatment effects were also validated by in vivo experiments. The underlying mechanisms involved in the synergistic effects were probably included: (1) increased activation of caspase cascade; (2) enhancement of DNA damage degree and (3) induction of p53 phosphorylation at Serine 46.
TG potentiated 5-FU's inhibitory activity to human colorectal cancer through arresting cell cycle progression and inducing p53-mediated apoptosis, which may present a novel strategy in CRC therapies and contribute to the optimizing clinical application of 5-FU.
结直肠癌（CRC）是全球最恶性的肿瘤之一，预后差，生存率低。由于常用的 5-氟尿嘧啶（5-FU）为基础的化疗在 CRC 患者中的临床疗效有限，因为其不可耐受的不良反应，因此迫切需要探索能够增强 5-FU 的抗癌活性、降低不良反应和预防耐药性的药物。
本研究旨在探讨田七苷 G（TG）与 5-FU 联合抑制结直肠癌细胞的协同作用。
采用 CCK-8 法检测 TG 对 5 种结直肠癌细胞系的增殖抑制作用。采用 CompuSyn 软件中的 T.C. Chou 法，通过等效应线分析和组合指数法检测 TG 和 5-FU 的协同作用。通过流式细胞术检测 TG/5-FU 联合作用对细胞周期分布和凋亡诱导的影响。采用碱性彗星试验评价细胞 DNA 损伤程度。通过 Western blot 检测 TG/5-FU 联合作用调控的蛋白表达。此外，建立异种移植小鼠模型，研究体内协同抗肿瘤作用。
本工作首次观察到来源于田七（Marsdenia tenacissima（Roxb.）Wight et Arn）的单体物质 TG 对结直肠癌细胞具有剂量依赖性的生长抑制活性和细胞周期阻滞诱导作用。发现 TG 首次增强了 5-FU 的抗癌作用，具有协同作用。体内实验也验证了联合治疗效果。协同作用的潜在机制可能包括：（1）增加半胱天冬酶级联的激活；（2）增强 DNA 损伤程度；（3）诱导 p53 丝氨酸 46 磷酸化。
TG 通过阻滞细胞周期进程和诱导 p53 介导的细胞凋亡增强 5-FU 的抑制活性，可能为 CRC 治疗提供新策略，并有助于优化 5-FU 的临床应用。
