低pH环境通过下调外泌体CD280强化肿瘤细胞内吞促进Ori-AlPcS-Exo发挥多级靶向抗胃癌的研究

To solve such shortcomings as poor water solubility and non-targeting ability of the highly effective anti-gastric cancer compound oridonin screened in the early stage, the research group constructed the Ori-AlPcS-Exo synergetic gastric cancer treatment system combining exosome loading of oridonin with al(III) phthalocyanine chloride tetrasulfonic acid. The therapeutic evaluation found that this system features good tumor tissue targeting ability but poor tumor cells targeting ability, which may affect the therapeutic effect. To improve the targeting ability of tumor cells, exosomes secreted by cells under different stress state were compared, and low pH environment was found to have significantly improved the efficiency of endocytosis. Mass spectrum analysis suggested that low pH environment down-regulated the CD280 molecules in exosomes and increased the endocytic efficiency of tumor cells by decreasing its adhesion to ECM. Ori-AlPcS-ExoH gastric cancer treatment system constructed by utilizing the exosomes with high efficiency endocytosis has multi-level targeting ability from tissue to cell to subcell, which achieves efficient, accurate drug delivery. Combined with controlled drug release and synergistic effects of this system, multipoint efficient anti-cancer effect was achieved. This subject would carry out a systematic in-depth study concerning molecular mechanisms that exosomes with high efficiency endocytosis are low pH environment mediated and improve efficacy as drug carriers, and further expand the universal application of exosomes with high efficiency endocytosis as drug carries on the basis of constructing highly efficient gastric cancer treatment system.

为解决前期筛选到的高效抗胃癌化合物冬凌草甲素水溶性差及无靶向性的缺点，课题组构建了外泌体装载冬凌草甲素-磺化铝酞菁与光动力协同抗胃癌治疗体系(Ori-AlPcS-Exo)，该体系具有较好的肿瘤组织靶向性，但肿瘤细胞靶向性较差，影响疗效发挥。为提高肿瘤细胞靶向，比较不同应激状态细胞所分泌外泌体，发现低pH环境明显提高内吞效率，质谱分析提示低pH环境下调外泌体中CD280分子，通过降低与ECM的黏附力提高肿瘤细胞内吞效率。利用高内吞效率外泌体构建Ori-AlPcS-ExoH胃癌治疗体系，使其具有组织-细胞-亚细胞水平的多级靶向，实现药物高效精准递送，结合该体系所具有药物控释及协同作用的特点，发挥多点高效抗胃癌作用。本课题将对低pH环境介导外泌体高内吞效率的分子机制以及高内吞效率外泌体作为药物载体提升疗效进行研究，在构建高效胃癌治疗体系基础上进一步拓展高内吞效率的外泌体作为药物载体的普适性应用。

胃癌是一个多因素、多阶段、多步骤的发生发展过程，现有抗肿瘤药物由于靶向性弱导致副作用大，治疗效果欠佳，提高治疗药物的靶向性是当今肿瘤治疗研究领域的关键和热点问题。为解决筛选到的高效抗胃癌化合物冬凌草甲素水溶性差以及无靶向性的缺点，本课题组构建了外泌体装载冬凌草甲素-磺化铝酞菁与光动力协同胃癌治疗体系Ori-AlPcS-Exo，疗效评价发现该体系具有较好的肿瘤组织靶向性。为提高肿瘤细胞靶向，比较不同应激状态细胞所分泌外泌体，发现低pH环境明显提高内吞效率，质谱分析提示低pH环境下调外泌体中CD280分子，通过降低与ECM的黏附力提高肿瘤细胞内吞效率。利用高内吞效率外泌体构建LP-ExosAlp+Ori胃癌治疗体系，使其具有组织-细胞-亚细胞水平的多级靶向，实现药物高效精准递送，结合该体系所具有药物控释及协同作用的特点，发挥多点高效抗胃癌作用。在体外与其他组相比，CCK-8和细胞存活分析表明，LP-ExosAlp+Ori处理组显示出最强的生存抑制作用。在体内，LP-ExosAlp+Ori对MGC803来源的肿瘤移植瘤有明显的抑制作用，不仅减少了肿瘤细胞，而且延长了小鼠的寿命，再次显示了增强的抗肿瘤作用。.本课题对低pH环境介导外泌体高内吞效率的分子机制以及高内吞效率外泌体作为药物载体提升疗效进行研究，在构建高效胃癌治疗体系基础上进一步拓展高内吞效率的外泌体作为药物载体的普适性应用。受外泌体自然特性的启发，我们评估了各种细胞应激条件对肿瘤迭代外泌体吸收效率的影响，发现低ph值处理引起了吸收效率的提高和细胞类型特异性的保留。脂质组学分析和分子动力学模拟揭示了增强同源摄取的基于甘油脂自聚集的机制。此外，这些低ph重编程的外泌体被开发成智能药物传递平台，能够特异性靶向肿瘤细胞，选择性释放多种化学药物，以响应近红外辐照触发活性氧爆发的外泌体破裂。该平台具有安全、增强的抗肿瘤作用，经多模型小鼠实验证明。这些结果为重新编程外泌体进行智能药物递送和针对其同源肿瘤的潜在个性化治疗开辟了新的途径。

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