Pettersen Ingvild, Bakkelund Wenche, Smedsrød Bård, Sveinbjørnsson Baldur
Department of Experimental Pathology, Medical Faculty, University of Tromsø, N-9037, Tromsø, Norway.
Anticancer Res. 2005 Nov-Dec;25(6B):3809-16.
Osteoprotegerin (OPG), a soluble member of the tumor necrosis factor family, is produced by various cell types and tissues and plays a key role in the physiological regulation of osteoclast differentiation and activity. Also, OPG is a soluble decoy receptor for tumor necrosis factor-related apoptosis-inducing factor (TRAIL). In the present study we investigated whether the human colon cancer cell lines HT-29 and SW-480 produce and secrete OPG in vitro.
Expression of OPG mRNA was examined by RT-PCR. OPG protein was analysed by ELISA assay and immunostaining methods. The effect of OPG secretion on TRAIL-mediated apoptosis was also investigated.
By RT-PCR, it was demonstrated that mRNA transcripts for OPG were produced by both cell lines. By ELISA analysis, OPG was detected in the culture medium; and treatment of cells with proinflammatory cytokines TNF-alpha and IL-1beta increased OPG secretion significantly. Tumor xenografts in nude mice also were shown to express OPG by immunohistochemistry. When RANKL, which selectively binds OPG, was added to cell cultures along with recombinant TRAIL, apoptosis was shown to increase significantly.
These data indicate that OPG may be involved in tumorigenesis and the progression of colon cancer.
骨保护素（OPG）是肿瘤坏死因子家族的可溶性成员，由多种细胞类型和组织产生，在破骨细胞分化和活性的生理调节中起关键作用。此外，OPG是肿瘤坏死因子相关凋亡诱导因子（TRAIL）的可溶性诱饵受体。在本研究中，我们调查了人结肠癌细胞系HT-29和SW-480在体外是否产生和分泌OPG。
通过逆转录聚合酶链反应（RT-PCR）检测OPG mRNA的表达。通过酶联免疫吸附测定（ELISA）和免疫染色方法分析OPG蛋白。还研究了OPG分泌对TRAIL介导的细胞凋亡的影响。
通过RT-PCR证明两种细胞系均产生OPG的mRNA转录本。通过ELISA分析，在培养基中检测到OPG；用促炎细胞因子肿瘤坏死因子-α（TNF-α）和白细胞介素-1β（IL-1β）处理细胞可显著增加OPG分泌。裸鼠体内的肿瘤异种移植物通过免疫组织化学也显示表达OPG。当将选择性结合OPG的核因子κB受体活化因子配体（RANKL）与重组TRAIL一起添加到细胞培养物中时，细胞凋亡显著增加。
这些数据表明OPG可能参与结肠癌的肿瘤发生和进展。
