Department of Infection, Beijing Friendship Hospital, Capital Medical University, 95 Yong-An Road, Beijing 100050, People's Republic of China.
J Gastrointest Surg. 2011 Apr;15(4):652-9. doi: 10.1007/s11605-011-1445-6. Epub 2011 Feb 12.
Osteopontin (OPN), a phosphorylated glycoprotein, is involved in tumor progression and metastasis. Previously, we have reported that high OPN mRNA expression level possessed clinicopathological or prognostic significance in human colorectal cancer (CRC). The aim of this study is to investigate whether OPN can serve as a novel molecular target for CRC therapy.
Western Blot assay was performed to detect the expression of OPN protein in 18 CRC and corresponding nontumor colon tissue samples. RNA interference (RNAi) was employed to knockdown endogenous OPN expression in CRC cell line (LoVo). MTT, colony formation, and tumorigenicity assays were performed to analyze the effect of OPN downregulation on the in vitro and in vivo proliferation of CRC cells. Wound healing and Matrigel invasion assays were performed to analyze the effect of OPN downregulation on migration and invasion of CRC cells. A clonogenic cell survival assay after radiation was performed to analyze the effect of OPN downregulation on the radiosensitivity of CRC cells.
The relative level of OPN protein expression in CRC tissues was significantly higher than that in corresponding nontumor colon tissues (P < 0.05). We found that RNAi-mediated OPN downregulation could inhibit not only in vitro proliferation but also in vivo tumorigenicity of CRC cells. In addition, OPN downregulation could suppress in vitro invasion capacity and enhance in vitro radiosensitivity of CRC cells, which might be associated with decreased levels of MMP-2 and -9 expression.
RNAi-targeting OPN could inhibit proliferation, invasion and enhance radiosensitivity of human CRC cells. Therefore, OPN could serve as a novel molecular target for gene therapy of CRC.
骨桥蛋白（OPN）是一种磷酸化糖蛋白，参与肿瘤的进展和转移。先前，我们已经报道了 OPN 的高 mRNA 表达水平在人结直肠癌（CRC）中具有临床病理或预后意义。本研究的目的是研究 OPN 是否可以作为 CRC 治疗的新的分子靶标。
通过 Western Blot 检测 18 例 CRC 及其相应非肿瘤结肠组织样本中 OPN 蛋白的表达。采用 RNA 干扰（RNAi）技术敲低 CRC 细胞系（LoVo）中内源性 OPN 的表达。MTT、集落形成和肿瘤发生测定用于分析 OPN 下调对 CRC 细胞体外和体内增殖的影响。划痕愈合和 Matrigel 侵袭测定用于分析 OPN 下调对 CRC 细胞迁移和侵袭的影响。进行克隆形成细胞存活测定后辐射，以分析 OPN 下调对 CRC 细胞放射敏感性的影响。
CRC 组织中 OPN 蛋白表达的相对水平明显高于相应的非肿瘤结肠组织（P<0.05）。我们发现，RNAi 介导的 OPN 下调不仅可以抑制 CRC 细胞的体外增殖，还可以抑制体内肿瘤生成。此外，OPN 下调可抑制 CRC 细胞的体外侵袭能力，并增强体外放射敏感性，这可能与 MMP-2 和 MMP-9 表达水平降低有关。
靶向 OPN 的 RNAi 可抑制人 CRC 细胞的增殖、侵袭并增强其放射敏感性。因此，OPN 可作为 CRC 基因治疗的新的分子靶标。
