铃兰毒苷通过 JAK2/STAT3（T705）和 mTOR/STAT3（S727）信号通路的串扰促进结直肠癌的细胞凋亡并抑制增殖和血管生成。
Convallatoxin promotes apoptosis and inhibits proliferation and angiogenesis through crosstalk between JAK2/STAT3 (T705) and mTOR/STAT3 (S727) signaling pathways in colorectal cancer.
机构信息
Key Laboratory of Natural Resources of Changbai Mountain & Functional Molecules, Molecular Medicine Research Center, Ministry of education, College of Pharmacy, Yanbian University, Yanji 133002, Jilin Province, China.
Yanbian University Affiliated Hospital/Liver Diseases Branch, China.
出版信息
Phytomedicine. 2020 Mar;68:153172. doi: 10.1016/j.phymed.2020.153172. Epub 2020 Jan 17.
BACKGROUND
Aberrant activation of STAT3 is frequently encountered and promotes survival, cellular proliferation, migration, invasion and angiogenesis in tumor cell. Convallatoxin, triterpenoid ingredient, exhibits anticancer pharmacological properties.
PURPOSE
In this work, we investigated the anticancer potential of convallatoxin and explored whether convallatoxin mediates its effect through interference with the STAT3 activation in colorectal cancer cells.
METHODS
In vitro, the underlying mechanisms of convallatoxin at inhibiting STAT3 activation were investigated by homology modeling and molecular docking, luciferase reporter assay, MTT assay, RT-PCR, Western blotting and immunofluorescence assays. Changes in cellular proliferation, apoptosis, migration, invasion and angiogenesis were analyzed by EdU labeling assay, colony formation assay, flow cytometry assay, wound-healing assay, matrigel transwell invasion assay and tube formation assays. And in vivo, antitumor activity of convallatoxin was assessed in a murine xenograft model of HCT116 cells.
RESULTS
Convallatoxin decreased the viability of colorectal cancer lines. Moreover, convallatoxin reduced the P-STAT3 (T705) via the JAK1, JAK2, and Src pathways and inhibited serine-727 phosphorylation of STAT3 via the PI3K-AKT-mTOR-STAT3 pathways in colorectal cancer cells. Interestingly, we discovered the crosstalk between mTOR and JAK2 in mTOR/STAT3 and JAK/STAT3 pathways, which collaboratively regulated STAT3 activation and convallatoxin play a role in it. Convallatoxin also downregulated the expression of target genes involved cell survival (e.g., Survivin, Bcl-xl, Bcl-2), proliferation (e.g., Cyclin D1), metastasis (e.g., MMP-9), and angiogenesis (e.g., VEGF). Indeed, we found that convallatoxin inhibited tube formation, migration, and invasion of endothelial cells, and inhibited the proliferation. Finally, in vivo observations were confirmed by showing antitumor activity of convallatoxin in a murine xenograft model.
CONCLUSION
The result of the current study show that convallatoxin promotes apoptosis and inhibits proliferation and angiogenesis through crosstalk between JAK2/STAT3 (T705) and mTOR/STAT3 (S727) signaling pathways in colorectal cancer cells and indicate that convallatoxin could be a valuable candidate for the development of colorectal cancer therapeutic.
背景
STAT3 的异常激活在肿瘤细胞中经常发生，并促进其存活、细胞增殖、迁移、侵袭和血管生成。鬼臼毒素是一种三萜类成分，具有抗癌的药理作用。
目的
在这项工作中，我们研究了鬼臼毒素的抗癌潜力，并探讨了鬼臼毒素是否通过干扰结直肠癌细胞中 STAT3 的激活来发挥其作用。
方法
在体外，通过同源建模和分子对接、荧光素酶报告基因检测、MTT 检测、RT-PCR、Western blot 和免疫荧光检测，研究了鬼臼毒素抑制 STAT3 激活的潜在机制。通过 EdU 标记检测、集落形成检测、流式细胞术检测、划痕愈合检测、基质胶 Transwell 侵袭检测和管形成检测，分析细胞增殖、凋亡、迁移、侵袭和血管生成的变化。在体内，通过 HCT116 细胞的小鼠异种移植模型评估鬼臼毒素的抗肿瘤活性。
结果
鬼臼毒素降低了结直肠癌细胞系的活力。此外，鬼臼毒素通过 JAK1、JAK2 和Src 通路降低了 P-STAT3（T705），并通过 PI3K-AKT-mTOR-STAT3 通路抑制了 STAT3 的丝氨酸-727 磷酸化。有趣的是，我们发现了 mTOR 和 JAK2 在 mTOR/STAT3 和 JAK/STAT3 通路中的相互作用，它们共同调节 STAT3 的激活，而鬼臼毒素在其中发挥作用。鬼臼毒素还下调了参与细胞存活（如 Survivin、Bcl-xl、Bcl-2）、增殖（如 Cyclin D1）、转移（如 MMP-9）和血管生成（如 VEGF）的靶基因的表达。事实上，我们发现鬼臼毒素抑制了内皮细胞的管形成、迁移和侵袭，并抑制了增殖。最后，在体内观察到鬼臼毒素在小鼠异种移植模型中具有抗肿瘤活性，证实了这一结果。
结论
本研究结果表明，鬼臼毒素通过结直肠癌细胞中 JAK2/STAT3（T705）和 mTOR/STAT3（S727）信号通路的相互作用促进凋亡，抑制增殖和血管生成，并表明鬼臼毒素可能是开发结直肠癌治疗方法的有价值的候选药物。
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