Department of Oral and Maxillofacial Surgery, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 2-5-1 Shikata-cho, Kita-ku, Okayama 700-8525, Japan.
Oral Oncol. 2012 Nov;48(11):1120-7. doi: 10.1016/j.oraloncology.2012.05.009. Epub 2012 Jun 12.
Angiogenin (ANG) is a prominent angiogenic factor that has been shown to have a dual effect on tumor progression by inducing both angiogenesis and cancer cell proliferation through stimulating ribosomal RNA transcription in both endothelial cells and cancer cells. In the present study, we investigated the expression profiles of ANG and vascular endothelial growth factor (VEGF) in oral cancer and their correlation with hypoxia and evaluated the possible value of ANG as a therapeutic target for oral cancer.
Immunohistochemistry (IHC), ELISA, real-time RT-PCR and Western blotting were used to examine the expression of ANG, VEGF, and hypoxia-inducible factor 1α (HIF-1α) in oral squamous cell carcinoma (OSCC) specimens and human OSCC cell lines. In order to examine the role of ANG, we knocked down ANG expression in HSC-2 cells by means of plasmid-mediated RNA interference.
IHC showed that the expression of ANG was significantly correlated with that of HIF-1α in 50 OSCC specimens (P = 0.031). However, no significant correlation between VEGF and HIF-1α expression was found (P = 0.243). Consistently, ANG secretion increased under hypoxia in all of the 10 OSCC cell lines tested; and a significant increase was observed in 6 of them. In contrast, there was no noticeable increase in VEGF secretion under hypoxia in any of these cell lines. In HSC-2 and SAS OSCC cells, the increase in ANG mRNA expression correlated very well with that of HIF-1α protein expression after hypoxia onset. However, no noticeable increase in VEGF mRNA expression was observed even after 12 h of hypoxia. Down-regulation of ANG expression in HSC-2 cells highly expressing and secreting VEGF inhibited ribosome biogenesis, cell proliferation, tumor angiogenesis, and xenograft growth in athymic mice.
These results suggest that ANG is up-regulated in the hypoxic environment of oral cancers and that its inhibition can have a therapeutic implication.
血管生成素 (ANG) 是一种重要的血管生成因子，它通过刺激内皮细胞和癌细胞的核糖体 RNA 转录，既能诱导血管生成，又能促进癌细胞增殖，从而对肿瘤进展产生双重作用。本研究旨在探讨口腔癌中 ANG 和血管内皮生长因子 (VEGF) 的表达谱及其与缺氧的相关性，并评估 ANG 作为口腔癌治疗靶点的可能价值。
采用免疫组织化学 (IHC)、ELISA、实时 RT-PCR 和 Western blot 检测 50 例口腔鳞状细胞癌 (OSCC) 标本和人 OSCC 细胞系中 ANG、VEGF 和缺氧诱导因子 1α (HIF-1α) 的表达。为了研究 ANG 的作用，我们通过质粒介导的 RNA 干扰下调了 HSC-2 细胞中的 ANG 表达。
IHC 结果显示，在 50 例 OSCC 标本中，ANG 的表达与 HIF-1α的表达显著相关 (P = 0.031)。然而，VEGF 与 HIF-1α表达之间无显著相关性 (P = 0.243)。同样，在所有 10 种检测的 OSCC 细胞系中，ANG 的分泌在缺氧条件下均显著增加，其中 6 种细胞系增加明显。相比之下，在任何这些细胞系中，VEGF 的分泌在缺氧条件下均无明显增加。在 HSC-2 和 SAS OSCC 细胞中，缺氧后 ANG mRNA 表达的增加与 HIF-1α 蛋白表达的增加非常吻合。然而，即使在缺氧 12 小时后，VEGF mRNA 表达也没有明显增加。下调高表达和分泌 VEGF 的 HSC-2 细胞中的 ANG 表达，可抑制核糖体生物发生、细胞增殖、肿瘤血管生成和裸鼠异种移植瘤生长。
这些结果表明，ANG 在口腔癌的低氧环境中上调，其抑制可能具有治疗意义。
