基于B2AR/CREB/FOXP3途径研究右美托咪定调控的调节性T细胞对乳腺癌术后转移和复发的影响

For most breast cancer patients, surgery is commonly used as the crucial and necessary treatment for eradicating the primary tumor. However, an increased risk exists for facilitating the growth of pre-existing micrometastases in the perioperative period, which is attributed to the postsurgical suppression of the cell-mediated immunity (CMI). It has been well documented that surgery profoundly suppresses many aspects of CMI and thus promotes the postoperative metastatic recurrence. Regulatory T cell (Treg), characterized by classical markers CD25 and FOXP3, can exert a broad suppressive effect on anti-tumor immunity, ultimately resulting in immunological tolerance and escape in tumor cells. Elevation of CD4+CD25+FOXP3+ Tregs in peripheral blood has been demonstrated to be associated with higher risk of tumor recurrence and poor prognosis in breast cancer patients. Our previous work demonstrated that catecholamines induced by surgical stress enhanced both number and function of Tregs postoperatively. Nevertheless, the underlying mechanisms and their impacts on metastasis and recurrence in breast cancer remain elusive. The present study will observe that the impact of reduced catecholamines secretion induced by dexmedetomidine on the postoperative number and function of Treg in patients undergoing radical mastectomy at first. Then we will investigate the role of B2AR/CREB/FOXP3 signaling in regulating Treg differentiation and FOXP3 transcription by dexmedetomidine. At last, animal models will be applied to further verify that dexmedetomidine could inhibit the increase of Tregs and ultimately reduce the risk of metastasis and recurrence in cancer. This project will provide a new strategy and target for clinical guideline of perioperative drug use and improve the clinical outcomes of breast cancer patient.

乳腺癌的转移和复发是引起乳腺癌患者死亡的首要原因。据报道，围术期发生的免疫功能抑制可促进微转移形成，对乳腺癌的转移和复发起着关键作用。调节性T细胞构成细胞免疫的重要部分，可抑制机体抗肿瘤免疫，与乳腺癌的发生发展及转移复发均密切相关。前期研究发现手术应激释放的儿茶酚胺可提高乳腺癌患者术后调节性T细胞的数量和功能，但其具体机制及对乳腺癌转移和复发的影响尚未清楚。本研究首先在临床上观察右美托咪定通过降低儿茶酚胺分泌，对乳腺癌患者术后调节性T细胞数量和功能的影响；其次体外探讨B2AR/CREB/FOXP3通路在右美托咪定调控调节性T细胞分化及功能基因FOXP3表达中的作用；最后构建动物模型进一步验证围术期应用右美托咪定可通过抑制手术应激反应，减少术后激增的调节性T细胞，从而降低肿瘤转移和复发风险。以期阐明右美托咪定影响乳腺癌转移和复发的具体机制，为临床指导围术期用药以改善肿瘤预后提供新策略与新靶点。

右美托咪定是一种新型的高选择性α2-肾上腺素能受体（α2-AR）激动剂，在临床上除了应用于围手术期镇静、镇痛、催眠外，还有一定的抗交感神经作用，可降低应激、减轻术后炎症反应，但对肿瘤的作用目前尚未清楚。因机体免疫功能与肿瘤的发生发展及转移复发均密切相关，而CD4 T细胞构成细胞免疫的重要部分，故我们首先在体外检测了右美托咪定对CD4 T细胞活化、增殖和凋亡的作用，结果发现其可介导CD4 T细胞内质网应激促其凋亡并抑制其活化和增殖，具体机制仍有待进一步研究。在此基础上，我们进一步检测了右美托咪定对人肝癌细胞的生长、增殖、侵袭和凋亡的作用，发现通过MiR-130a/早期生长反应蛋白1（Early growth response 1，EGR1）轴，右美托咪定可直接抑制SMMC-7721肝癌细胞的增殖和侵袭，并促进其凋亡，在此我们首次证明了右美托咪定诱导的MiR-130a可在基因转录水平上直接调控肝癌细胞EGR1的表达。此外，为了进一步拓宽右美托咪定的临床意义，我们还探索了其对脑保护的作用及机制，通过采用双侧颈总动脉夹闭联合低血压建立脑缺血再灌注模型，发现右美托咪定可降低大鼠海马GluR2、NR2B的表达并减轻脑缺血再灌注所致的神经功能损伤，为围术期指导临床用药提供新策略。最后，我们还利用生物信息学手段，筛选临床上介导人胶质瘤GBM对替莫唑胺（Temozolomide，TMZ）耐药的基因，发现人HTLV-1病毒感染相关基因CDKN1A可通过磷酸化AKT调控GBM的TMZ耐药性，对GBM肿瘤的发生发展和治疗起重要作用。该项目资助内容已发表1篇CSCD核心期刊，1篇SCI已接收，2篇待投。参与培养博士研究生3名。项目投入经费20万元，支出17.8924万元，各项支出基本与预算相符。剩余经费2.1076万元，计划用于后续文章发表支出。