Zhao Zhigang, He Jun, Kang Ran, Zhao Shankun, Liu Luhao, Li Futian
Department of Urology and Andrology, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong Province, China.
Prostate. 2016 Feb;76(2):184-98. doi: 10.1002/pros.23110. Epub 2015 Oct 19.
Prostate stem cell antigen (PSCA) is a cell surface, glycosylphosphatidylinositol (GPI)-anchored glycoprotein. Its overexpression has been detected in both local and metastatic prostate cancer (PCa), making it a potential therapeutic target. We previously reported that silencing PSCA by small interfering RNA targeting human PSCA (siRNA-PSCA) inhibited biological activity of PSCA-positive PCa cells leading to reduced proliferation, motility and invasion in vitro. In this study, we extended this in vitro findings to in vivo settings in order to investigate the effects of this specific siRNA on the tumor growth and metastasis development of PCa in vivo.
The siRNA-PSCA and ectopically overexpressed-PSCA vector were constructed and transfected into human PCa PC-3M and LNCaP cells, respectively, and were subcutaneously inoculated into the male SCID mice. Tumor growth was measured with a caliper, and formation of metastasis in mice bearing xenograft tumors was studied by magnetic resonance imaging (MRI) and autopsy analysis. Western blot and immunohistochemistry were used to assess the expression levels of PSCA protein in tumor tissues from xenograft and distant metastases.
Consistent with our previous in vitro findings, the subcutaneous xenografts of PC-3M-siPSCA exhibited the almost completely inhibited expression of PSCA protein in their tumors tissues (P < 0.001 and P < 0.001, respectively), and consequently had a significant reduction in tumor growth volumes (P < 0.05 for all), and metastasis onset and sites (P < 0.001 for all) compared to those of PC-3M and PC-3M-siScrm. Conversely, LNCaP-PSCA showed significantly enhanced primary tumor growth and metastasis formation of xenografts compared to LNCaP-vehicle and LNCaP cells (P < 0.001 for all). Moreover, the up-regulated expression of PSCA protein was detected in the distant metastases of xenograft tumors from all groups.
Taken together, these observations suggest that PSCA has a promoting role in the growth and metastasis of PCa and siRNA-PSCA may be a potential therapeutic strategy for PSCA-positive PCa.
前列腺干细胞抗原（PSCA）是一种细胞表面糖基磷脂酰肌醇（GPI）锚定糖蛋白。在局部和转移性前列腺癌（PCa）中均检测到其过表达，使其成为一个潜在的治疗靶点。我们之前报道，通过靶向人PSCA的小干扰RNA（siRNA-PSCA）沉默PSCA可抑制PSCA阳性PCa细胞的生物学活性，导致其体外增殖、运动和侵袭能力降低。在本研究中，我们将这一体外研究结果扩展至体内环境，以研究这种特异性siRNA对PCa体内肿瘤生长和转移发展的影响。
构建siRNA-PSCA和异位过表达PSCA载体，分别转染人PCa细胞PC-3M和LNCaP，然后皮下接种到雄性SCID小鼠体内。用卡尺测量肿瘤生长情况，通过磁共振成像（MRI）和尸检分析研究荷瘤小鼠的转移形成情况。采用蛋白质免疫印迹法和免疫组织化学法评估移植瘤和远处转移瘤组织中PSCA蛋白的表达水平。
与我们之前的体外研究结果一致，PC-3M-siPSCA皮下移植瘤的肿瘤组织中PSCA蛋白表达几乎完全被抑制（分别为P < 0.001和P < 0.001），因此与PC-3M和PC-3M-siScrm相比，肿瘤生长体积显著减小（均为P < 0.05），转移起始和转移部位也显著减少（均为P < 0.001）。相反，与LNCaP-空载体组和LNCaP细胞相比，LNCaP-PSCA移植瘤的原发性肿瘤生长和转移形成显著增强（均为P < 0.001）。此外，在所有组移植瘤的远处转移灶中均检测到PSCA蛋白表达上调。
综上所述，这些观察结果表明PSCA在PCa的生长和转移中起促进作用，siRNA-PSCA可能是PSCA阳性PCa的一种潜在治疗策略。
