Gabril M Y, Onita T, Ji P G, Sakai H, Chan F L, Koropatnick J, Chin J L, Moussa M, Xuan J W
Department of Surgery, University of Western Ontario, Canada.
Gene Ther. 2002 Dec;9(23):1589-99. doi: 10.1038/sj.gt.3301895.
To date, only a few prostate-specific vector genes have been tested for prostate targeting in gene therapy of prostate cancer (CaP). Current clinical trials of gene therapy of CaP utilize the only two available vector genes with a combination of a rat probasin promoter and a human PSA promoter sequence in an adenovirus vector to target CaP. There is an urgent need to establish additional vector gene systems to sustain and propagate the current research. Since PSP94 (prostate secretory protein of 94 amino acids) is one of the three most abundant proteins secreted from the human prostate and is generally considered to be prostate tissue-specific in both human and rodents, we performed a transgenic experiment to assess the promoter/enhancer region of PSP94 gene-directed prostate targeting. Firstly, a series of progressive deletion mutants of a 3.84 kb PSP94 gene promoter/enhancer region (including parts of the intron 1 sequence) linked with a reporter LacZ gene was constructed and assessed in vitro in cell culture. Next, transgenic mice were generated with two transgene constructs using the SV40 early region (Tag oncogene) as a selection marker. PSP94 gene promoter/enhancer region-directed SV40 Tag expression specifically in the mouse was demonstrated in three breeding lines (A, B, C, n = 374) by immunohistochemistry staining of Tag expression. Specific targeting to the prostate in the PSP94 gene-directed transgenic CaP model was characterized histologically by correlation of SV40 Tag-induced tumorigenesis (tumor grading) with puberty and age (10-32 weeks). Prostatic hyperplasia was observed as early as 10 weeks of age, with subsequent emergence of prostatic intraepithelial neoplasia (PIN) and eventually high grade carcinoma in the prostate. The PSP94 transgenic mouse CaP model was further characterized by its tumor progression and metastatic tendency at 20 weeks of age and also by its responsiveness and refractoriness to androgen manipulation. This study indicates that the PSP94 gene promoter/enhancer has the potential for prostate specific targeting and may ultimately be of use in gene therapy of CaP.
迄今为止，在前列腺癌（CaP）基因治疗中，仅有少数前列腺特异性载体基因被用于前列腺靶向性测试。目前CaP基因治疗的临床试验利用腺病毒载体中仅有的两种可用载体基因，并结合大鼠前列腺素启动子和人前列腺特异性抗原（PSA）启动子序列来靶向CaP。迫切需要建立更多的载体基因系统来维持和推进当前的研究。由于PSP94（94个氨基酸的前列腺分泌蛋白）是人类前列腺分泌的三种最丰富的蛋白质之一，并且在人类和啮齿动物中通常被认为是前列腺组织特异性的，我们进行了一项转基因实验，以评估PSP94基因指导的前列腺靶向的启动子/增强子区域。首先，构建了一系列与报告基因LacZ相连的3.84 kb PSP94基因启动子/增强子区域（包括部分内含子1序列）的渐进缺失突变体，并在细胞培养中进行体外评估。接下来，使用SV40早期区域（Tag癌基因）作为选择标记，用两种转基因构建体产生转基因小鼠。通过Tag表达的免疫组织化学染色，在三个繁殖系（A、B、C，n = 374）中证明了PSP94基因启动子/增强子区域指导的SV40 Tag在小鼠中的特异性表达。在PSP94基因指导的转基因CaP模型中，通过将SV40 Tag诱导的肿瘤发生（肿瘤分级）与青春期和年龄（10 - 32周）相关联，从组织学上对前列腺的特异性靶向进行了表征。早在10周龄时就观察到前列腺增生，随后出现前列腺上皮内瘤变（PIN），最终在前列腺中出现高级别癌。PSP94转基因小鼠CaP模型在20周龄时进一步通过其肿瘤进展和转移倾向以及对雄激素操纵的反应性和难治性进行了表征。这项研究表明，PSP94基因启动子/增强子具有前列腺特异性靶向的潜力，最终可能用于CaP的基因治疗。
