肝癌进展新标志物-SARI阳性EVs抑制CAFs激活及趋化作用及其分子机制研究

The diagnosis and treatment of HCC has long been faced with the problem of insufficient efficacy biomarkers. It is urgent to explore novel markers that can reflect the progress of HCC progression. Proteins in EVs can be used as effective circulating markers in the early diagnosis of HCC. SARI (suppressor of AP-1, regulated by IFN) is an important transcription factor that regulates the tumor microenvironment and thus inhibits tumor development. Our previous studies found that: 1) SARI expression is negatively correlated with the malignancy of HCC; 2) SARI expression in EVs and the proportions of SARI+EVs in peripheral blood of HCC patients is significantly down-regulated; 3) SARI can inhibit the growth and spontaneous metastasis of orthotropic HCC; 4) SARI+EVs can inhibit in vitro chemotaxis of CAFs. However, dose HCC progression mediated by inhibition of CAFs activation by SARI-positive EVs? The mechanisms are still unclear. Therefore, this study intends to further explore the molecular mechanism of inhibition of CAFs activation by SARI+EVs, a novel marker of HCC progression, and provide experimental and theoretical basis for SARI+EVs as a circulating marker reflecting the progression of HCC.

肝癌的诊疗长期面临现有标志物效能不足的问题，迫切需要探索能够反映肝癌进展的新标志物，EVs中的蛋白能够作为有效的循环标志物应用在肝癌的早期诊断中。SARI（suppressor of AP-1, regulated by IFN）是一个重要的转录因子，具有调节肿瘤微环境从而抑制肿瘤发展的作用。我们前期研究发现：1）SARI的表达与肝癌恶性程度呈负相关；2）在肝癌病人外周血中SARI+EVs比例明显下调并且EVs中SARI的表达下调；3）SARI能够抑制原位肝癌生长和自发转移；4）SARI+EVs抑制肿瘤成纤维细胞的体外趋化。但是，SARI+EVs抑制CAFs激活及趋化介导肝癌发展的作用机制尚不清楚，也未见文献报道。因此，本课题拟进一步探讨肝癌进展新标志物SARI+EVs抑制CAFs形成活化的分子机制，为SARI+EVs成为反映肝癌进展的循环标志物提供实验基础和理论依据。

SARI即BATF2，全名碱性亮氨酸拉链ATF样转录因子2 (The basic leucine zipper ATF-like transcription factor 2，BATF2，又名SARI)，是一个与炎症反应和抗肿瘤作用密切相关的基因。因为在工程化外泌体构建的过程中，我们发现肝癌细胞得到的SARI+EVs不够稳定，使得本项目在肝癌中无法进行下去（2020已提交年度进展报告）。因此，我们将本研究调整为研究SARI+EV在神经胶质瘤中的作用。目前，对于 SARI是否参与维持肿瘤微环境尚不清晰。我们的研究表明，SARI (BATF2) 可以抑制神经胶质瘤(glioblastoma multiforme, GBM)的生长和骨髓源抑制细胞(MDSCs)的招募。上调SARI的神经胶质瘤细胞U87-SARI分泌的细胞外囊泡(Extracellular vesicles, EVs)可以稳定的载有SARI蛋白，这些 SARI-EVs具有抑制MDSCs趋化的作用。在机制上来说，SARI抑制细胞内SDF-1α的分泌，并导致EVs中的SDF-1α量也减少。通过用AMD3100阻断SDF-1α/AMD3100轴，可以逆转SARI下调导致的MDSCs趋化作用。在对临床样本中，我们发现：通过计数血浆中SARI阳性EVs（SARI+plEVs）的数目，可以把I-II期GBM患者、III-IV期GBM患者和健康供血者有效地分开。我们的研究表明:载有SARI的EVs具有调节MDSCs招募的作用， SARI+plEVs具有可以作为预测GBM分期标志物的潜力。

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