Caspase-3介导的肿瘤再生在肿瘤损伤应激后复发与转移中的作用

Tumors are prone to occur recurrence and metastasis after radiotherapy and chemotherapy. Our preliminary studies showed that increased caspase-3 activity can be observed when the melanoma cells cultured in vitro were treated with adriamycin, accompanied with decreased tumor volume and increased metastastic rates of the transplanted melanoma. We further observed that caspase-3 in tumor cells can promote the migration and metastastic ability of tumor cells and related with the prognosis of melanoma patients，speculating that caspase-3 may play a role in tumor recurrence and metastasis after chemoradiotherapy. This project aims to investigate the impacts of tumor cell death induced by chemoradiotherapy on the growth and metastastic ability of tumor cells through the technology by which tumor cells are proportionally premixed to simulate the tumor cell populations in which dead and surviving tumor cells coexist after radiotherapy and chemotherapy and anlyse the the role of caspase-3 in the process; Besides, the sensitizing effect of caspase-3 inhibitor combined with chemoradiotherapy will be observed based on the tumor bearing animal model. The relation between caspas-3 and tumor biological behaviour as well as prognosis of tumor patients will be validated via human tumor specimens. Furthermore, the molecular mechanism of the regeneration of tumor induced by caspase-3 after tumor chemoradiotherapy will be investegated via the microarray expression profiling methods. The project will help to clarify the essential reason of the impacts of chemoradiotherapy on the growth and metastastic ability of tumor cells.

肿瘤放、化疗后易复发、转移。前期工作发现经阿霉素处理的肿瘤细胞caspase-3活性增高，移植瘤体积减小，但肿瘤的肺转移率却增加；也观察到caspase-3可促进肿瘤细胞的侵袭和转移能力；因此考虑caspase-3的激活可能与肿瘤放、化疗后的复发、转移相关；本项目拟在原工作基础上，通过肿瘤细胞按比例预混的方法，模拟肿瘤放、化疗后死亡与存活的肿瘤细胞共存的细胞群体，并通过荧光素酶进行标记，探讨放、化疗诱导的细胞死亡对存活肿瘤细胞生长和转移能力的影响，并分析caspase-3在其中的作用；在动物模型上观察caspase-3抑制剂与放、化疗联用后是否具有增敏作用。利用人体肿瘤标本进一步验证caspase-3与肿瘤生物学行为及患者预后的关系。最后通过表达谱芯片的方法探讨放、化疗诱导的caspase-3的激活促进肿瘤再生的可能分子机制。该项目有助于阐明放、化疗对肿瘤复发和转移影响的本质原因。

对肿瘤的放、化疗等治疗方式在大量杀伤肿瘤细胞的同时，是否会作为一种“应激损伤”因素，使肿瘤细胞做出应激反应和适应性改变,促进肿瘤对恶劣环境的适应，增加肿瘤的恶性潜能，从而最终促进残余肿瘤的播散转移及其分子机制并不清楚。研究表明，通过触发caspase而诱导肿瘤细胞凋亡的效果并不理想，还有大量研究均证实了caspase抑制剂在抑制肿瘤细胞凋亡的同时，可以促进肿瘤细胞的其他死亡途径，前期研究也发现，caspase-3可以表达于非凋亡的肿瘤细胞中，且caspase-3高表达的肿瘤其血管密度较高，肿瘤转移率高、患者预后差。本课题按照研究计划探讨了化疗介导的肿瘤细胞死亡及caspase-3的激活对肿瘤恶性演进的促进作用，通过体外化疗诱导的死亡细胞与活细胞预混的方式，发现化疗介导的肿瘤细胞死亡可以促进残存活细胞的快速生长和迁移、侵袭能力；此外，进一步通过荧光素酶标记肿瘤细胞，验证了死亡细胞对残存的存活肿瘤细胞转移能力的促进作用；进一步的分子机制研究表明，化疗药介导的肿瘤细胞死亡，可以促进残存肿瘤细胞发生“食尸”行为，启动了胸苷磷酸化酶（TP）的表达和分泌以利用死亡细胞的胞内或胞外的戊糖苷作为碳源获得 EMT 所需的基本能量，进而促进肿瘤侵袭转移。基于这些重要的分子机制发现，课题组进一步开发了基于肿瘤应激调控通路的抗肿瘤药物，筛选了一批活性较好的化合物，其中一项已获得CFDA临床试验批文。项目发表SCI论文7篇，达到申请书额定指标，申请结题。