黄芩新素抑制STAT3改善肿瘤微环境免疫抑制的机制研究

Signal transducer and activators of transcription 3(STAT3) plays a dual role in tumor cell growth and immunosuppression of tumor microenvironment. Our preceding screening of anti-tumor active substances in Scutellaria baicalensis with surface plasmon resonance analysis technology (SPR), reveals that neobaicalein is a specific STAT3 inhibitor. Our experiment shows that neobaicalein can specifically bind to STAT3, inhibit the activity of STAT3 and eliminate the effect of tumor cell culture supernatant (TCM) on the maturation of dendritic cells (DC). Therefore, we assume that neobaicalein can improve the immunosuppressive status of tumor microenvironment by inhibiting STAT3 activity, thus exerting its anti-tumor effect. In order to confirm this proposal, we plan to systemically study the effect of neobaicalein on TCM stimulating DC and STAT3 signaling pathway in macrophage, and observe the inhibitory effect of neobaicalein on the function of these two kinds of cells in vitro. We plan to select mouse tumor cells that resistant to neobaicalein induced apoptosis as in vivo model, observe the effects of neobaicalein on DC, tumor-related macrophages, natural killer cells (NK), cytotoxic T cells and regulatory T cells, further study the relationship between blocking tumor immune escape, inhibiting tumor cell growth and the inhibition of STAT3. We plan to use CD4/8 and NK antibodies to confirm the anti-tumor effect of neobaicalein through enhancing immunity. This study is expected to elucidate the key mechanism of neobaicalein in improving immunosuppression of tumor microenvironment, and provide theoretical and experimental basis for the study of anti-tumor drugs and targets of Scutellaria baicalensis Georgi, as well as the use of Scutellaria baicalensis Georgi in anti-tumor immunotherapy.

信号转导和转录活化因子3 (STAT3) 在肿瘤细胞生长及肿瘤微环境免疫抑制中起着双重作用。课题组前期应用表面等离子共振分析技术发现黄芩中黄芩新素能特异性结合STAT3，抑制STAT3活性以及消除肿瘤细胞培养上清(TCM)抑制树突状细胞(DC)成熟的作用。据此提出假设：黄芩新素可能通过抑制STAT3，改善肿瘤微环境的免疫抑制发挥抗肿瘤作用。本课题拟在体外研究黄芩新素对TCM刺激DC、巨噬细胞STAT3通路以及抑制两种细胞功能的影响；挑选耐黄芩新素凋亡的小鼠肿瘤细胞为体内模型，研究黄芩新素调控DC、肿瘤相关巨噬细胞、自然杀伤细胞(NK)、细胞毒T细胞和调节性T细胞的功能，阻断肿瘤免疫逃逸，抑制肿瘤细胞生长的作用与其抑制STAT3的关系，并用CD4/8和NK抗体确证黄芩新素通过提高免疫力发挥抗肿瘤作用，阐明黄芩抗肿瘤作用的药效物质和作用靶点，为用黄芩新素进行抗肿瘤免疫治疗提供依据。

信号转导和转录活化因子3 (STAT3) 在肿瘤细胞生长及肿瘤微环境免疫抑制中起着双重作用。课题组前期发现黄芩中的黄芩新素能特异性结合并抑制STAT3，且在体外可消除肿瘤细胞培养上清(TCM)抑制树突状细胞(DC)成熟的作用，据此进一步研究黄芩新素的抗肿瘤的作用及其机制。课题组发现药物可直接抑制肿瘤细胞增殖、对其凋亡、迁移等恶性表型也有一定抑制作用；黄芩新素在体外可影响肿瘤细胞上清中炎症因子表达水平，可抑制肿瘤细胞上清刺激的小鼠骨髓来源DC与TAM中STAT3的活化水平，影响这些免疫细胞的表型和功能；体内实验中黄芩新素对荷瘤小鼠的体重无影响，可抑制移植瘤生长；且药物可抑制LPS刺激的肿瘤增长；PD-L1抗体与药物可协同抑制移植瘤生长。课题组建立了移植瘤中肿瘤组织浸润的巨噬细胞、T细胞、DC细胞等表型与功能变化的检测方法，并检测了另一个STAT3特异性抑制药物CTS-65，发现其能抑制CT26移植瘤的生长和肿瘤部位STAT3的活化，同时，肿瘤组织中Ki-67、PD-L1的表达也受到抑制，对肿瘤浸润性T细胞功能有增强作用，同时可抑制肿瘤组织中树突状细胞的浸润与功能。针对黄芩新素及其他黄芩黄酮水溶性较差，生物利用度不高的缺点，课题组设计并合成了光化学纳米载药颗粒，提高了黄芩中黄酮类物质的生物利用度和肿瘤靶向性。课题为阐明黄芩抗肿瘤作用的药效物质和作用靶点提供了实验依据，同时为提高黄芩中黄酮的肿瘤靶向性，为临床使用黄芩中黄酮抗肿瘤治疗提供理论和实验基础。