化疗一直是治疗多种癌症的主要方法。尤其是在治疗皮肤癌方面，局部使用化疗药物已经被广泛采用。虽然有效，但由于局部毒性和甚至系统毒性等副作用，局部化疗受到了限制。我们最近的研究表明，接触治疗药物等促氧化应激剂能诱导生成所谓微小泡（microvesicle particles，MVP）的细胞外囊泡，这种现象取决于各种细胞类型上存在的G蛋白偶联受体——血小板活化因子受体（Platelet-activating factor-receptor，PAFR），以及一种称为酸性鞘磷脂酶（acid sphingomyelinase，aSMase）的酶，该酶在MVP生成中发挥重要作用。基于这个前提，我们检验了这样一个假设，即应用吉西他滨可以在人类和小鼠皮肤上诱导MVP的生成。我们的离体研究使用了人皮肤片段，结果表明吉西他滨的治疗能够以剂量依赖的方式诱导MVP的生成，并且这个过程可被PAFR拮抗剂和aSMase抑制剂所阻止。重要的是，由吉西他滨诱导产生的MVP携带PAFR激动剂。为了确认这个机制，我们采用了PAFR表达和缺失（Ptafr-/-）小鼠模型以及缺乏aSMase酶（Spmd1-/-）的小鼠。与药理学工具的研究结果相似，基于遗传的方法在野生型小鼠和Ptafr-/-和Spmd1-/-小鼠中显示出，吉西他滨诱导MVP释放的趋势下降。这些发现表明，局部化疗可以通过PAFR-aSMase途径诱导生物活性组分的产生，这是一种旁观效应。©2022 The Authors. BioFactors由Wiley Periodicals LLC代表国际生物化学和分子生物学联盟出版。

Chemotherapy has remained the mainstay for the treatment of multiple types of cancers. In particular, topical use of chemotherapy has been used for skin cancers. Though effective, topical chemotherapy has been limited due to adverse effects such as local and even systemic toxicities. Our recent studies demonstrated that exposure to pro-oxidative stressors, including therapeutic agents induces the generation of extracellular vesicles known as microvesicle particles (MVP) which are dependent on activation of the Platelet-activating factor-receptor (PAFR), a G-protein coupled receptor present on various cell types, and acid sphingomyelinase (aSMase), an enzyme required for MVP biogenesis. Based upon this premise, we tested the hypothesis that topical application of gemcitabine will induce MVP generation in human and murine skin. Our ex vivo studies using human skin explants demonstrate that gemcitabine treatment results in MVP generation in a dose-dependent manner in a process blocked by PAFR antagonist and aSMase inhibitor. Importantly, gemcitabine-induced MVPs carry PAFR agonists. To confirm the mechanisms, we employed PAFR-expressing and deficient (Ptafr-/- ) mouse models as well as mice deficient in aSMase enzyme (Spmd1-/- ). Similar to the findings using pharmacologic tools, genetic-based approaches demonstrate that gemcitabine-induced MVP release in WT mice was blunted in Ptafr-/- and Spmd1-/- mice. These findings demonstrate a novel mechanism by which local chemotherapy can generate bioactive components as a bystander effect in a process that is dependent upon the PAFR-aSMase pathway.© 2022 The Authors. BioFactors published by Wiley Periodicals LLC on behalf of International Union of Biochemistry and Molecular Biology.