前列腺干细胞抗原与前列腺癌

Prostate stem cell antigen and prostate cancer

人们对前列腺癌早期诊断的标志物及理想的治疗靶点的探寻从未停止过脚步。迄今为止，一批潜在的将用于诊治前列腺癌的候选蛋白逐步浮现。其中一个新发现的重要的生物标志物是前列腺干细胞抗原（PSCA）。PSCA是一种糖化磷脂酰肌醇（GPI）锚定的细胞膜表面糖蛋白，属于Thy-1/Ly-6家族成员之一，在人前列腺癌细胞中高表达，在正常前列腺组织中表达有限。正是这样的组织特异性，使其成为前列腺癌诊断和预后判断的一个潜在的标志物和颇具吸引力的免疫治疗的候选靶点。研究显示，PSCA表达的增加与前列腺癌Gleason评分、肿瘤分期和骨转移均具有相关性。PSCA作为前列腺癌特异的膜抗原，具有严格的表达模式，现其已被作为免疫治疗的靶点而进行深入研究，如利用单克隆抗体、结合细胞毒的抗体、遗传工程T细胞、PSCA疫苗和负载肽段的树突状细胞（DC）等手段进行免疫治疗。本文主要对PSCA在前列腺癌诊断、预后判断、治疗等方面的研究加以综述，同时简要介绍一些PSCA在其他肿瘤中与在前列腺癌中表达情况不同的研究报告。

The pursuit of early diagnostic biomarker and ideal therapeutic target for prostate cancer has never been stopped. So far, a number of proteins have emerged as potential clinical candidates in the treatment. One of most important novel biomarker is prostate stem cell antigen （PSCA）. PSCA is a glycosylphosphatidylinositol （GPI）-anchored cell surface protein that belongs to the LY-6/thy-1 family. It is highly over-expressed in human prostate cancer cells, but is mildly expressed in normal tissues. This restricted expression profile makes it be a potential biomarker of diagnosis and prognosis for prostate cancer, and an attractive candidate target for immunotherapy. Many investigations have revealed that PSCA expression is positively correlated with Gleason score, tumor stage and bone metastasis in prostate cancer. Since PSCA is a prostate cancer-specific membrane antigen and has restricted pattern of expression, it has been targeted in several immunotherapeutic strategies, including monoclonal antibodies, antibodies conjugated to cytotoxins, genetically engineered T cells, PSCA vaccination and peptide-loaded dendritic cells （DC）. This article presents the currents progress of PSCA in the diagnosis, prognosis and therapy for prostate cancer, and provides a general introduction of some different findings about its expression in other cancers.