Division of Diagnostic Pathology, Keio University Hospital, Tokyo, Japan.
Lab Invest. 2011 Oct;91(10):1443-58. doi: 10.1038/labinvest.2011.111. Epub 2011 Aug 1.
The Snail family transcription factors have been proposed as important mediators of epithelial-mesenchymal transition because of their role in down-regulation of E-cadherin and up-regulation of matrix metalloproteinases (MMPs). The present study was undertaken to investigate the expression of Snail, Slug and their associations with cancer invasion and prognosis in renal cell carcinomas (RCCs). Ninety-seven primary RCCs were analyzed for the protein expression of Snail, Slug, MMP2 and MMP9 by immunohistochemistry. Snail protein expression level was positively correlated with pathological tumor stage, histological grade and the presence of sarcomatoid carcinoma. On the contrary, Slug protein expression level was negatively correlated with pathological tumor stage, suggesting that Slug was down-regulated in advanced RCCs. Because Snail was positively associated with malignant potential of RCCs, involvement of Snail in the invasiveness of an RCC cell line 786-O was examined in the Matrigel invasion assay by down-regulating the gene expression with small interfering RNA (siRNA). Targeting the Snail, not Slug, expression in 786-O cells with siRNA caused down-regulation of the gene expression of Snail, vimentin, MMP2 and MMP9, but up-regulated the E-cadherin. Invasion of the cells through Matrigel in vitro was inhibited under this condition. Furthermore, expression levels of MMP2 and MMP9 were positively correlated with pathological tumor stage and the presence of sarcomatoid carcinoma. Statistical analysis indicated that elevated Snail, MMP2 and MMP9 protein expression are significantly worse predictors of disease-free and disease-specific survival of the patients with RCC. In conclusion, these data suggest that Snail has an important role in invasion and metastasis, and that silencing the gene may be a potential therapeutic target in RCCs.
蜗牛家族转录因子已被提议作为上皮间质转化的重要介质，因为它们在下调 E-钙粘蛋白和上调基质金属蛋白酶（MMPs）方面发挥作用。本研究旨在探讨蜗牛、Slug 及其与肾细胞癌（RCC）侵袭和预后的关系。通过免疫组织化学法分析了 97 例原发性 RCC 中蜗牛、Slug 及其与 MMP2 和 MMP9 的蛋白表达。蜗牛蛋白表达水平与病理肿瘤分期、组织学分级和肉瘤样癌的存在呈正相关。相反，Slug 蛋白表达水平与病理肿瘤分期呈负相关，提示 Slug 在晚期 RCC 中下调。由于蜗牛与 RCC 的恶性潜能呈正相关，因此通过小干扰 RNA（siRNA）下调基因表达，在 Matrigel 侵袭试验中检查了蜗牛参与 RCC 细胞系 786-O 侵袭的情况。用 siRNA 靶向 786-O 细胞中的蜗牛，而不是 Slug，表达导致蜗牛、波形蛋白、MMP2 和 MMP9 的基因表达下调，但 E-钙粘蛋白上调。在这种条件下，细胞体外穿过 Matrigel 的侵袭受到抑制。此外，MMP2 和 MMP9 的表达水平与病理肿瘤分期和肉瘤样癌的存在呈正相关。统计分析表明，MMP2 和 MMP9 蛋白表达升高是预测 RCC 患者无病和疾病特异性生存的显著不良指标。总之，这些数据表明，蜗牛在侵袭和转移中具有重要作用，沉默该基因可能是 RCC 的潜在治疗靶点。
