阿司匹林对结肠癌肿瘤微环境的影响及机制研究

High-quality evidence suggests that aspirin is a promising agent for cancer prevention and treatment. Direct inhibition of cyclooxygenase-2 (COX-2) pathway is generally thought to be the main mechanism by which aspirin inhibits cancer development. However, either pharmacological properties of aspirin or recent results of epidemiologic studies do not support that mechanism. To address this inconsistency, we hypothesize that antiplatelet effect of aspirin via inhibition of COX-1 may be one of potential mechanisms to inhibit carcinogenesis. Aberrant platelet activation will lead to promote hostility of tumor microenvironment by releasing an abundant array of angiogenesis regulators. Given the outstanding ability of antiplatelet, aspirin may restore balance of pro- and anti-angiogenic factors released from platelet to “normalize” tumor vasculature and shape tumor microenvironment to some extent, which will not only diminish tumor aggressiveness and progression, but also enhance the sensitivity to therapeutic treatment. Thus, targeting the platelet activation leading to alter tumor microenvironment may provide a novel way to tumor therapy..The present study explores the potential of the anti-neoplastic action of aspirin in transplantable mice tumor model of a spontaneously originated colon cancer . Aspirin administered to tumor-bearing mice through oral is measured via estimation of survival of tumor-bearing mice, tumor cell viability, tumor progression and changes in the tumor microenvironment. kinetic changes in vascular morphology are detected under a con focal microscope with immunofluorescent staining in carcinomas in mice, and the vascular permeability is quantified by the amount of diffused dextran by Image Pro Plus 6.0 software.The expression of glucoproteins on the platelet membrane is quantified by flow cytometric immunology . Real-time quantitative PCR, immunohistochemical staining and western blot are applied to detect the mRNA or protein expression of tumor microenvironment, respectively. In vitro study of platelet on colon cancer microenvironment, HCT116 is cultured with platelet-rich plasma. The comparison of differnt level of aspirin on the releasing of tumor angiogenic regulatory factors was measured by ELISA. CCK8 assay is used to observe the effects of aspirin on growth. Transwell chamber is used for cell migration detection. ALDH-1 expression is detected by flow cytometry..This project will help to further understand the role of platelets in tumor microenvironment and provide theoretical basis for antiplatelet drugs used in cancer prevention and treatment.

阿司匹林可降低多种恶性肿瘤的风险，但作用机制不明。我们前期研究提示阿司匹林可改善结肠癌的缺氧微环境。肿瘤缺氧微环境，与促血管生成因子和抑制因子比例失衡造成的肿瘤血管结构及功能异常密切相关。血小板含有大量的血管生成调节因子，但在肿瘤微环境中以分泌促血管生成因子为主，因此我们推测阿司匹林可通过抑制血小板的异常激活，调整其分泌血管生成因子的失衡状态，进而改善肿瘤微环境。本课题拟通过建立阿司匹林干预的结肠癌移植瘤裸鼠模型，采用激光共聚焦观察移植瘤血管形态及功能，流式细胞仪检测血小板活化率，免疫组化、Western blot和RT-PCR检测肿瘤缺氧、糖代谢等微环境指标。再以富血小板血浆培养结肠癌细胞，ELISA检测阿司匹林干预后上清液中血管调节因子的种类及数量的变化，同时对肿瘤细胞的生物学特性进行评估。本项目将有助于进一步了解血小板在肿瘤微环境中的作用，并为抗血小板药物应用于肿瘤防治提供理论依据。