ALA-PDT能有效治疗皮肤鳞状细胞癌 (SCC)，但其机制仍不完全清楚。本课题组前期研究观察到ALA-PDT可以明显促进SCC分泌exosome，PDT后SCC细胞分泌的exosome可明显抑制SCC细胞体外增殖，下调细胞内ERK的表达。由于exosome是调节细胞间相互作用的重要媒介，鳞癌中ERK的表达受miR-124调控。由此推测，exosome可能通过转移miR-124，在ALA-PDT抑制皮肤肿瘤生长中发挥重要作用。为证实以上假设，本项目拟在已培养小鼠皮肤鳞癌细胞及前期研究基础上，进一步研究exosome在ALA-PDT抑制SCC生长中的作用及机制；在对exosome成分分析的基础上，重点研究miR-124的作用及分子机制。本项目的完成，有助于深入认识ALA光动力抑制皮肤鳞癌生长的机制，为提高ALA-PDT治疗SCC的临床疗效提供新的理论基础。

Squamous cell carcinoma (SCC) was treated by ALA-photodynamic therapy (ALA-PDT) and achieved satisfied outcomes, however, its mechanism remains unclear. According to our previous study,ALA-PDT enhances exosome secretion of SCC cell. Exosome secreted by ALA-PDT treated SCC cell suppressed proliferation of SCC cell in vitro and down-regulate the expression of ERK which is regulated by miR-124 .Exosome is thought to play important roles in intercellular communications. We hypothesize that exosome is very important for suppressing growth of SCC by ALA-PDT via mediating transfer of miR-124.In order to confirm the hypothesis, we have primary cultured mouse SCC cell in vitro. We will confirm that exosome secreted by ALA-PDT treated SCC cell can suppress growth of SCC. We will identify the microRNA in exosome, analyze the regulatory role and molecular mechanism of miR-124 in ALA-PDT suppressing growth of SCC by exosome .An insight view into the mechanism can throw lights on the new mechanism of ALA-PDT treatment of SCC, and provide new theoretical evidence on the clinical effect.