两种莎草属植物中抗炎与抗肿瘤活性倍半萜的发现及其对肝癌防治的作用机理

Persistent inflammation is known to promote and exacerbate malignancy. Primary liver cancer, mostly hepatocellular carcinoma, is a clear example of inflammation-related cancer. Sesquiterpene lactones are a family of natural products which showed good anti-inflammation activity and cytotoxicity on cancer cells, and some of them have been studied as potential anti-tumor agents in clinic, e.g. Artemisinin. Cyperus rotundus is a Traditional Chinese Medicine (TCM) recorded in China Pharmacopeia. Sesquiterpenes isolated from C. rotundus showed anti-tumor activity. CP-01, a new sesquiterpene lactone isolated from C. papyrus by us, was found to show cytotoxicity on several cancer cell lines including 2 hepatic carcinoma ones. CP-01 also showed potent inhibitory activity in the activation NF-kB pathway, which provides a critical link between inflammation and cancer. Additionally, CP-01 downregulated the levels of IL-6 and TNF-α in LPS-activated mouse macrophage Raw264.4 cells. Based on the above work, we will continue the chemical study of C. papyrus and C. rotundus, and isolate more sesquiterpenes from these plants. By cytotoxicity and NF-kB activation assays, more active sesquiterpenes will be found especially the new active ones. For the potent inhibition in NF-kB activation, inhibitory mechanism of sesquiterpene from C. papyrus and C. rotundus in this pathway will be studied, so as to JAK-STAT pathway, which is also known to play vital roles in cytokine signaling pathways involved in cell growth and differentiation. The antifibrotic activity of the sesquiterpenes also will be studied by using heptocytes, hepatic stellate sells and Kupffer cells. Finally, we will study their activity in prevention and treatment in rat hepatocellular carcinoma induced by diethylnitrosamine. This study will promote the R&D research of sesquiterpenes from C. papyrus and C. rotundus as anti-tumor or anti-inflammation agents.

炎症与肿瘤关系密切，肝细胞癌是炎症与恶性肿瘤关系的典型。天然倍半萜内酯具有强烈细胞毒及抗炎作用，有的已被作为抗肿瘤药物开发如青蒿素。《中国药典》收载的中药香附为莎草科莎草属植物莎草（Cyperus rotundus）的干燥根茎，其中的倍半萜成分有抗肿瘤活性。前期我们从其同属植物纸莎草（C. papyrus）中发现新倍半萜内酯CP-01对肝癌在内的多种肿瘤细胞有较好细胞毒性，对炎症和肿瘤关系密切的NF-kB通路有强烈抑制活性，还能抑制LPS诱导巨噬细胞所致的重要炎症介质的水平。因此我们将开展纸莎草和莎草中的化学成分研究，通过筛选发现更多新的活性倍半萜；对以CP-01为代表的活性倍半萜对与炎症关系密切的NF-kB和JAK-STAT通路的调控机制开展研究，并探讨其对肝纤维化的调控机理；用大鼠原位肝癌模型考察其对肝癌的防治作用。此研究将促进莎草属植物中倍半萜成分作为抗肝癌或抗炎药物的研发。

炎症与肿瘤关系密切，肝细胞癌是炎症与恶性肿瘤关系的典型。JAK2/STAT3信号通路与炎症和癌症的关系密切， JAK2和STAT3蛋白在多种癌细胞中异常高表达，该通路的异常活化能加速肿瘤细胞的增殖和恶性转移，促进肿瘤组织内新生血管生成，促进肿瘤免疫逃逸，并抑制癌细胞凋亡。天然倍半萜类化合物具有多种生物活性，尤其是在抗癌和抗肿瘤方面具有较好的药理活性。基于此我们对富含倍半萜成分的两种莎草属植物开展了以下工作：1）通过化学成分研究，从香附和纸莎草中分离得到60多个天然倍半萜类成分，包括6个新倍半萜和1个新骨架倍半萜化合物；2）通过活性筛选研究发现，这些倍半萜大多对炎症因子IL-6诱导的JAK2/STAT3信号通路的活化有抑制作用；3）体内活性研究发现，富含倍半萜的香附活性成分能够显著缓解D-GalN/ LPS所造成的小鼠急性肝损伤；4）富含倍半萜的香附活性成分对DEN所致的小鼠原位肝癌有一定的治疗作用，尤其是与临床肝癌治疗药物索拉非尼联合使用，能够显著提高小鼠生存时间和生存率，并对症状有一定的缓解作用；5）体内外活性研究发现，活性成分的作用与其抑制肝纤维化和抑制JAK2/STAT3信号通路的激活密切相关：能够显著降低小鼠肝脏组织中JAK2和STAT3蛋白的水平，抑制其磷酸化，抑制该通路在肝组织中的过度活化，从而影响肝癌细胞的增殖，促进其细胞凋亡，达到抗肝癌的作用。该研究丰富了莎草属植物的化学成分，为阐明中药香附的临床应用提供了理论基础，并有望促进具有抗肝损伤和抗肝癌作用的中成药物的研究与开发。