Department of Pathology, Soochow University School of Medicine, Suzhou, China.
Cancer Sci. 2010 May;101(5):1108-16. doi: 10.1111/j.1349-7006.2010.01512.x. Epub 2010 Mar 7.
Overexpression of transforming growth factor-beta1 (TGF-beta1) and its downstream molecules in the rhabdomyosarcoma (RMS) RD cell line has been reported previously, but the regulatory role of TGF-beta1 on RMS has not been studied extensively. In the present study, we showed that expression of TGF-beta1 and its downstream molecules type II TGF-beta receptor (TbetaRII) and Smad4 was significantly higher in RMS than in normal skeletal muscle, and there was a significant relationship between TGF-beta1 expression and histological grade. Gene silencing with TGF-beta1 short-hairpin RNA (shRNA)-expressing vectors significantly decreased the growth of RD cells, which was confirmed by caspase-3 (in vitro) and TUNEL (in vivo) assays. Moreover, a proportion of treated rhabdomyosarcoma (RD) cells changed to a round shape from the normal fusiform or polygonal shape and expressed myofilaments. Myogenin is one of the myogenic differentiation genes (MyoD) family of myogenic regulators, and was obviously higher in TGF-beta1-shRNA-treated tumors than it in control at the mRNA and protein level. Immunohistochemical staining with myogenic differentiation markers such as myosin and desmin in subcutaneous RMS tissue showed that TGF-beta1 shRNA increased staining for myosin. These results provide new insight into the biological function of TGF-beta1 in malignant tumors, and imply that the TGF-beta1 signal pathway is a potential therapeutic target for drugs that induce differentiation of RMS.
先前已有报道称横纹肌肉瘤（RMS）RD 细胞系中转化生长因子-β1（TGF-β1）及其下游分子过度表达，但 TGF-β1 对 RMS 的调节作用尚未得到广泛研究。本研究表明，与正常骨骼肌相比，TGF-β1 及其下游分子Ⅱ型 TGF-β受体（TβRII）和 Smad4 在 RMS 中的表达显著升高，且 TGF-β1 表达与组织学分级之间存在显著相关性。用 TGF-β1 短发夹 RNA（shRNA）表达载体进行基因沉默显著降低了 RD 细胞的生长，这通过体外 caspase-3（体外）和 TUNEL（体内）测定得到了证实。此外，一部分治疗后的横纹肌肉瘤（RD）细胞从正常的梭形或多边形形状转变为圆形，并表达肌丝。肌球蛋白生成素是肌生成调节因子肌球蛋白基因家族（MyoD）中的一种，其在 TGF-β1-shRNA 处理的肿瘤中的 mRNA 和蛋白水平均明显高于对照组。用肌球蛋白和结蛋白等肌分化标记物对皮下 RMS 组织进行免疫组织化学染色表明，TGF-β1 shRNA 增加了肌球蛋白的染色。这些结果为 TGF-β1 在恶性肿瘤中的生物学功能提供了新的见解，并暗示 TGF-β1 信号通路是诱导 RMS 分化的药物的潜在治疗靶点。
