小分子天然化合物促前列腺癌细胞衰老并调节其分泌体的机制研究

The new treatment strategies which use low dose chemotherapy drugs induces tumor cellular senescence have significant advantages, but the senescent cells secretion composition such as proinflammatory factor which can promote the adjacent cells proliferation, invasion and metastasis also need to be overcome. Therefore, many effeorts have been made to explor novel prosenescent mechanisms and search for the new promising agents. We have previously identified Marchantins,naturally-occuring bisbibenzyls with unique structure and low toxicity, can target proteasome and induce autophagic cell death in prostate cancer (PCa) cells, and low concentration of the compounds can also significantly induce PCa cells senescence, especially in the PCa drug-resistant cells. The inhibition activity of Akt/mTOR, induction of endoplasmic reticulum stress also occur in this process, however, no significant alteration was observed in DNA damage response which is typically activated in senescent cells.More importantly, marchantins attenuate the IL-6 secretion in senescent PCa cell.The project will further clarify the target(s) and prosenescent mechanisms by which marchantins act on. Investigation will be focused on how chemicals induce senescence, the roles of AKT/mTOR signaling and its downstream targets in induction of senescence.Furthermore,the composition and the pathways that regulate senescence-associated secretory factors will be investigated in this project. Also, animal trials are used to address the impact of secretory factors on bystanders and tumor microenvirament. The above study will finally confirm the novel mechanisms of marchantin compounds induce senescence, and lay the foundation for screening the effective drugs to treat PCa ,and particularly, drug tolerance PCa in the future.

采用低剂量化疗药物诱导肿瘤细胞衰老能显著降低药物毒性、提高疗效，但衰老细胞分泌体中的促炎因子等成分对临近细胞的促增殖、侵袭转移等负面作用亟待解决，也为探索促衰老及分泌调节的新机制、寻找新型促衰老药物提供了思路。本课题在前期发现的促衰老化合物中，地钱素类联苄天然产物结构独特，毒性较低，显著诱导前列腺癌（PCa）、特别是PCa耐药细胞衰老，抑制Akt/mTOR活性、诱导内质网应激，而且其抗炎活性能降低衰老细胞IL6的分泌，但对衰老中常见的DNA损伤应答无显著影响，作用机制独特。本项目拟探索该类化合物促PCa细胞、PCa耐药细胞衰老的靶点、作用机制和对分泌体组分的调节作用：研究Akt/mTOR途径及上下游调控因子在促衰老中的作用、与内质网应激及其它信号网络的关联；分析分泌体的组成及促炎因子的调节机制；动物水平确定衰老细胞的成瘤能力、分泌体对肿瘤微环境的影响以及化合物促PCa衰老的药效作用。

细胞因损伤可导致周期阻滞、缺乏增殖能力而进入衰老过程,然而衰老细胞的长期积累，特别是衰老相关分泌表型（SASP）可导致器官衰老、促进肿瘤等疾病发生的驱动者，因此靶向或清除衰老细胞、抑制SASP是延缓衰老、降低疾病风险的重要策略。本课题针对细胞衰老机制、发现新的SASP抑制剂等展开研究：1）新型抗炎联苄化合物MM和MC可诱导肿瘤耐药细胞、肿瘤细胞衰老，而不影响正常细胞。机制分析显示MM除了抑制经典的NF-κB信号，显著抑制转录因子TFEB的核转位并其下调炎性靶基因的转录，从而显著降低SASP的分泌和功能，并能显著降低阿霉素的毒副作用，动物实验效果显著；而MC可显著抑制IKK/NF-κB信号，与免疫激活剂联用具有协同增效作用；而且MC通过抑制蛋白酶体活性，与蛋白酶体抑制剂具有协同增效、减毒的作用。2)针对衰老细胞溶酶体数量增加且对药物耐受的机制，半合成的联苄衍生物RDN可靶向溶酶体，促进组织蛋白酶B从溶酶体转位至细胞核产生凋亡；并通过探针和质谱联用，确定RDN作用的药靶蛋白。3）内质网蛋白AGR2下调促进肿瘤细胞衰老、促进SASP表达，而上调AGR2可显著抑制小鼠炎症，分泌的AGR2通过二硫键与VEGFA直接结合而增强VEGFR2信号、促进血管新生，同时显著拮抗血管靶向药物贝伐珠单抗的药效但不影响卡博替尼的活性，可作为肿瘤用药选择标志物；并确定蛋白酶体抑制剂通过诱导AGR2的K89发生K48依赖的泛素化、通过自噬受体NBR1介导AGR2自噬降解，阐明蛋白酶体抑制剂协同增效贝伐珠单抗活性的分子基础。4）内质网蛋白RCN1在前列腺癌等肿瘤中高表达，下调RCN1后促进细胞凋亡、非常显著的诱导细胞衰老。5）其它：多药耐药细胞虽有衰老样表型，但beta-gal染色并不显著。筛选发现耐药细胞对HDAC抑制剂的敏感性提高近10倍；筛选的其它小分子化合物完成其抗肿瘤机制。总之，本课题明确内质网蛋白参与细胞衰老、发现新的SASP抑制剂，有创新性的研究成果，已发表SCI文章6篇、接受文章1篇（Oncogene）、投稿3篇。培养博士/硕士研究生11名，青年教师2名。