新疆紫草萘醌类化合物靶向STAT3抑制黑色素瘤迁移侵袭的作用机制及构效关系研究

Malignant melanoma is a highly aggressive cancer that resists most conventional treatment. In China, its incidence has increased alarmingly in recent years. The available conventional therapies for melanoma often carry tolerance, low response rate and high toxicity. Therefore novel targeted therapies are desperately needed. Studies show that STAT3, which constantly activated in human melanoma and promotes melanoma metastasis, is an important target in melanoma. We previously isolated and identified several naphthoquinone compounds from Arnebia euchroma (Royle) Johnst.. And found that these compounds exerted inhibitory effects in melanoma cell migration and invasion with low toxicity. Further study showed that the expression levels of phospho-STAT3 and STAT3 downstream targets VEGF, MMP-2 and Twist1 were all decreased by treatment. More importantly, overexpress STAT3 in A375 cells inhibited shikonin-mediated cell migration inhibition. These results indicated that naphthoquinone compound-mediated melanoma cell migration and invasion inhibition were associated with suppression of STAT3. In this project, we propose to further isolate and identify naphthoquinone compounds from Arnebia euchroma (Royle) Johnst., investigate the anti-metastatic mechanism and structure-activity relationship of naphthoquinone compounds targeting STAT3. The outcome of this project will provide crucial new information for research and development effective agents in treating melanoma.

恶性黑色素瘤是中国发病率增长最快的恶性肿瘤之一，极易发生转移，难以治疗，现有治疗措施都有诸多局限。因此，从天然产物中寻找新的靶向治疗药物，尤其是具有抑制黑色素瘤转移作用的化合物显得尤其重要。研究发现STAT3信号通路与黑色素瘤转移有密切关系，是抗黑色素瘤的重要靶标。我们在前期工作中，从新疆紫草中分离鉴定了多个萘醌类化合物，活性结果显示该类化合物可显著抑制黑色素瘤细胞迁移和侵袭，初步的作用机制研究显示该类成分抑制了STAT3的磷酸化和下游靶基因VEGF、MMP-2及Twist1的表达，同时过表达STAT3抑制了萘醌类化合物的肿瘤迁移抑制作用。提示了其抑制黑色素瘤迁移侵袭的作用与STAT3信号通路有关。本项目拟在前期工作基础上，进一步对新疆紫草中的萘醌类化合物进行系统分离，评价和研究该类成分抑制黑色素瘤转移的生物活性、作用机制及构效关系，为研究和开发选择性高的黑色素瘤转移抑制剂提供科学依据。

本课题以中药新疆紫草为原料，运用各种色谱技术从紫草中共分离得到30个化合物，并利用IR、UV、HRESIMS、NMR、ECD和OR等方法鉴定了21个化合物的结构，其中3个为新化合物。对以上化合物进行抗肿瘤活性筛选发现紫草素抗肿瘤活性最好。进一步的机制研究发现紫草素能通过抑制STAT3通路抑制肿瘤细胞增殖、迁移和侵袭。此外，我们首次发现紫草素能抑制黑色素瘤细胞在斑马鱼体内的增殖。本研究为紫草素开发成为新型STAT3抑制剂，用于肿瘤治疗提供了参考。