A Study of Vaccine Therapy for Prostate Cancer Using Prostate Stem Cell Antigen (PSCA)-Transfected Dendritic Cells

为了建立前列腺癌的遗传免疫治疗方法，以前列腺干细胞抗原（PSCA）为特异性抗原，我们利用RT-PCR技术从小鼠前列腺中克隆了mPSCA的cDNA，并尝试以小鼠前列腺癌细胞系（RM-1和RM-11）为靶细胞进行DNA疫苗治疗。这些前期研究表明，有必要建立其他的mPSCA蛋白在小鼠前列腺癌细胞系中的表达评价体系。为了满足这一需求，我们利用逆转录病毒载体制备了永久表达mPSCA或flag偶联mPSCA的RM-1细胞（RM-1mPSCA, RM-1FLAGmPSCA）和RM-11细胞（RM-11mPSCA, RM-11FLAGmPSCA）。本研究是为了评估这些细胞作为评估系统的有效性。为此，我们在体外研究了mPSCA和FLAGmPSCA表达存在与否对细胞增殖的影响。RM-1mPSCA、RM-1FLAGmPSCA、RM-11mPSCA和RM-11FLAGmPSCA的增殖曲线与RM-1和RM-11的增殖曲线相似。然后，在体内评估细胞的增殖能力。小鼠皮下植入RM-1、RM-1mPSCA或RM-1FLAGmPSCA，观察其增殖情况。这些肿瘤细胞系间的增殖无明显差异。因此，可以在蛋白质水平上比较这些细胞系的表达。因此，我们可以说，该小鼠模型可用于评估以mPSCA为靶点的DNA疫苗治疗或RNA疫苗治疗前列腺癌。

To establish genetic immunotherapy for prostate cancer, using prostate stem cell antigen (PSCA) as a specific antigen, we previously cloned cDNA of mPSCA from mouse prostate glands using RT-PCR and attempted DNA vaccine therapy, with mouse prostate cancer cell lines (RM-1 and RM-11) serving as target cells. These previous studies indicated the necessity of establishing some other evaluation systems for the expression of mPSCA protein in mouse prostate cancer cell lines. To meet this need, we prepared, using retrovirus vectors, RM-1 cells (RM-1mPSCA, RM-1FLAGmPSCA) and RM-11 cells (RM-11mPSCA, RM-11FLAGmPSCA) which permanently express mPSCA or FLAG-conjugated mPSCA.The present study was undertaken to evaluate the usefulness of these cells as an evaluation system. To this end, differences in cell proliferation depending on the presence or absence of mPSCA and FLAGmPSCA expression were investigated in vitro. The proliferation of RM-1mPSCA, RM-1FLAGmPSCA, RM-11mPSCA and RM-11FLAGmPSCA depicted a curve similar to that of RM-1 and RM-11 proliferation. Then, proliferation of the cells was evaluated in vivo. Mice were subcutaneously implanted with RM-1, RM-1mPSCA or RM-1FLAGmPSCA and their proliferation was examined. No marked difference in proliferation was noted among these tumor cell lines.Thus, it was possible to compare the expression of these cell lines at the protein level. We may therefore say that this mouse model is useful for evaluation of DNA vaccine therapy or RNA vaccine therapy for prostate cancer, with mPSCA serving as the target.