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基因免疫治疗，以前列腺癌干细胞抗原(PSCA)为特异性抗原，以小鼠前列腺癌RM-1和RM-11细胞为靶细胞，采用RT-PCR和DNA疫苗治疗方法，从小鼠前列腺癌组织中克隆了MPSCA基因。这些研究表明，有必要建立MPSCA蛋白在小鼠前列腺癌细胞系中表达的其他评价体系。为了满足这一需要，我们利用逆转录病毒载体制备了永久表达MPSCA或FLAG结合mPSCA的RM-1细胞(RM-1mPSCA，RM-1FLAGmPSCA)和RM-11细胞(RM-11mPSCA，RM-11FLAGmPSCA)。为此，我们在体外研究了有无MPSCA和FLAGmPSCA表达对细胞增殖的影响。Rm-1mPSCA、Rm-1FLAGmPSCA、Rm-11mPSCA和Rm-11FLAGmPSCA的增殖曲线与Rm-1和Rm-11相似。然后在体内检测细胞的增殖情况。将Rm-1、Rm-1mPSCA和Rm-1FLAGmPSCA植入小鼠皮下，观察其增殖情况。这些肿瘤细胞系在增殖方面没有明显差异，因此，在蛋白质水平上比较这些细胞系的表达是可能的。因此，我们可以说，该小鼠模型可用于以MPSCA为靶点的前列腺癌DNA疫苗或RNA疫苗治疗的评价。

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.