Coordenação de Pesquisa, Programa de Medicina Experimental, Instituto Nacional de Câncer, Rio de Janeiro, RJ, Brazil.
Prostate. 2012 Nov;72(15):1688-99. doi: 10.1002/pros.22523. Epub 2012 Apr 11.
Alternative splicing of the osteopontin (opn, spp1) gene generates three protein splicing isoforms (OPN-SI), designated as OPNa, OPNb, and OPNc, which have demonstrated specific roles in different tumor models. This work aims to investigate the roles of each OPN-SI in prostate cancer (PCa) progression by using in vivo and in vitro functional assays.
The expression levels of OPN-SI in prostate cell lines were analyzed by qRT-PCR. PC-3 was stably transfected with expression vectors containing OPNa, OPNb, and OPNc, as well as empty vector controls. PC-3 cells overexpressing each construct were analyzed for in vivo tumor growth and in relation to different aspects mimicking tumor progression, such as cell proliferation, migration, invasion, and soft agar colony formation.
OPN-SI are overexpressed in PCa as compared to non-tumoral prostate cell lines. OPNc and OPNb overexpressing cells significantly activated enhanced xenograft tumor growth and PC-3 proliferation, migration, invasion, and soft agar colony formation, as well as the expression of MMP-2, MMP-9, and VEGF. These isoforms also support sustained proliferative survival. We found that both OPNc and OPNb pro-tumorigenic roles are mainly mediated through PI3K signaling. Inhibition of this pathway by using LY294002 specifically inhibited tumor progression features evoked by OPNc and OPNb overexpression.
Our data provide evidence that both OPNc and OPNb splicing isoforms promote distinct aspects of PCa progression by inducing PI3K signaling. These data give support to strategies aiming to downregulate OPNc and OPNb expression as an approach to inhibit PCa progression.
骨桥蛋白（opn，spp1）基因的选择性剪接产生三种蛋白质剪接异构体（OPN-SI），分别命名为 OPNa、OPNb 和 OPNc，它们在不同的肿瘤模型中表现出特定的作用。本研究旨在通过体内和体外功能测定研究每个 OPN-SI 在前列腺癌（PCa）进展中的作用。
通过 qRT-PCR 分析前列腺细胞系中 OPN-SI 的表达水平。PC-3 细胞用含有 OPNa、OPNb 和 OPNc 的表达载体以及空载体对照稳定转染。分析过表达每种构建体的 PC-3 细胞的体内肿瘤生长情况，并与模拟肿瘤进展的不同方面相关联，如细胞增殖、迁移、侵袭和软琼脂集落形成。
与非肿瘤前列腺细胞系相比，OPN-SI 在 PCa 中过度表达。OPNc 和 OPNb 过表达细胞显著激活增强的异种移植肿瘤生长和 PC-3 增殖、迁移、侵袭和软琼脂集落形成，以及 MMP-2、MMP-9 和 VEGF 的表达。这些异构体也支持持续的增殖存活。我们发现，OPNc 和 OPNb 的促肿瘤作用主要是通过 PI3K 信号传导介导的。使用 LY294002 抑制该途径特异性抑制 OPNc 和 OPNb 过表达引起的肿瘤进展特征。
我们的数据提供了证据，证明 OPNc 和 OPNb 剪接异构体通过诱导 PI3K 信号传导促进 PCa 进展的不同方面。这些数据支持了旨在下调 OPNc 和 OPNb 表达作为抑制 PCa 进展的方法的策略。
