黄芩苷诱导肿瘤细胞老化参与大肠癌治疗新机制研究

Induction of cancer cell senescence has recently been recognized as a novel strategy and new direction for cancer therapy. In our efforts to explore the anti-tumor efficacy and mechanisms mediated by traditional Chinese herb monomers, we first discovered that Baicalin, a monomer derived from the Chinese herb of Scutellaria baicalensis Georgi, can induce cell senescence of human colon cancer resulting in significant inhibition of tumor cell growth. Based on our preliminary studies, we hypothesized that Baicalin has a strong anti-tumor activity through the induction of tumor cell senescence, which could be used as a novel anti-tumor drug for colon cancer therapy. To test our hypothesis, we will perform the following three specific aims, using both in vitro in cell culture studies and in vivo in animal models. 1) Identify molecular mechanisms and cellular biological processes responsible for induction of cell senescence in colon cancer mediated by Baicalin; 2) Explore the molecular signaling pathways that control the molecular and biological alterations induced by Baicalin in human colon cancer cells leading to cancer cell senescence; 3) Investigate the therapeutic effect and related molecular mechanisms of senescence induction mediated by Baicalin in vivo in humanized colon cancer models. We anticipate that the studies we propose in this application will improve our fundamental understanding of the novel mechanisms and cellular processes of senescence induction mediated by Baicalin in human colon cancer cells that we have recently identified. Importantly, our proposed studies will allow us to explore the possibility of utilizing Baicalin as a new drug and an effective strategy for human colon cancer treatment, and will provide critical insights for the development of novel anti-tumor monomer drugs from Chinese herbs and for the clinical applications of traditional Chinese medicine as well.

诱导肿瘤细胞老化是近年肿瘤治疗研究新的方向和热点。在中药单体抗肿瘤活性及机制研究过程中，申请人首次发现来源于中药黄芩的单体--黄芩苷能够诱导人大肠癌细胞老化，同时其在体外有较强的抗大肠癌细胞活性。据此，本项目提出黄芩苷可通过诱导肿瘤细胞老化进行大肠癌治疗这一假设。本项目以细胞及动物模型为基础，拟从体内及体外进行以下的深入研究：①明确黄芩苷对大肠癌细胞老化的诱导作用及相关细胞调控机制；②探讨黄芩苷调节胞内信号蛋白，诱导肿瘤细胞老化的相关信号通路；③探讨黄芩苷诱导肿瘤细胞老化治疗大肠癌的体内疗效及其相应的细胞分子机制。本研究的结果将阐明黄芩苷诱导大肠癌细胞老化及细胞调控的机制，以及黄芩苷对大肠癌细胞的生长和发展进程的影响。该研究将为大肠癌的治疗提供新的方案和实验依据，也为中药单体治疗大肠癌的研发和临床应用开拓新思路。

黄芩苷抑制癌细胞增殖的机制并未得到深入研究。本课题从研究黄芩苷的抗肿瘤活性着手，对其诱导肿瘤细胞老化的现象和机制进行了系统探讨。通过细胞水平的工作，发现：①黄芩苷具有广谱抑制肿瘤细胞活性，能够抑制人结肠癌、非小细胞肺癌、肝癌、胰腺癌以及黑色素瘤等多种细胞系的活力；②黄芩苷的抑制活性与其降低结肠癌细胞系HCT116和SW480的活性氧水平，从而诱导发生细胞衰老直接相关；③黄芩苷导致的细胞内低活性氧状态，引起了低氧诱导蛋白DEPP的表达上调；④DEPP通过与Ras相结合，激活Ras/Raf/MEK/ERK通路和下游p16INK4A/Rb通路，进而造成了结肠癌细胞的衰老。使用Balb/c裸鼠皮下接种HCT116细胞构建的人源移植瘤模型，在体内进一步验证了黄芩苷诱导肿瘤细胞衰老的机制。此外，同样具有抗氧化作用的化合物姜黄素和萝卜硫素也具有诱导肿瘤细胞衰老的功能及相似的机制。本研究不仅为抗氧化中药单体在肿瘤临床治疗中的应用提供了理论基础，更找到了这些单体诱导肿瘤细胞衰老过程的关键蛋白DEPP及其相关的信号通路，为DEPP作为肿瘤治疗的新靶点的应用奠定基础。