Ye Lv, Zhang Hongying, Zhang Li, Yang Guanghua, Ke Qi, Guo Hua, Bu Hong
Department of Pathology, West China Hospital, Sichuan University, Chengdu 610041, P.R. China.
Int J Oncol. 2006 Nov;29(5):1149-57.
Transforming growth factor-beta (TGF-beta) signals through membrane-bound heteromeric serine/threonine kinase receptors. Upon ligand binding, TGF-beta activates intracellular Smad proteins and regulates proliferation and apoptosis in various cell types. To demonstrate the effects of TGF-beta/Smad signal on growth and apoptosis of human embryonal rhabdomyosarcoma (RMS) cells, a strategy of RNAi-mediated 'gene silencing' of Smad4 was used to interrupt endogenous TGF-beta/Smad signaling in an RMS cell line, RD, and the regulation of exogenous TGF-beta1 to growth and apoptosis of the cells was also determined. Physiologically, TGF-beta/Smad signaling was essential for the normal growth of RD. The interruption of endogenous TGF-beta/Smad signaling by RNAi significantly suppressed the growth of RD cells and dramatically induced apoptosis of RD cells. Exogenous TGF-beta1 also inhibited the growth of RD cells, but had no effect on apoptosis. It also partially counteracted the growth inhibition and apoptosis induced by Smad4 silencing in RD cells. These findings provide a new insight into how TGF-beta/Smad signaling regulates the growth and apoptosis of cancer cells. Moreover, as a powerful tool, shRNA interference suppresses endogenous Smad4 gene expression and subsequently modulates cell growth and apoptosis, which may provide a novel basis for the development of rational intervention strategies in RMS therapy.
转化生长因子-β（TGF-β）通过膜结合的异源二聚体丝氨酸/苏氨酸激酶受体发出信号。配体结合后，TGF-β激活细胞内Smad蛋白，并调节各种细胞类型的增殖和凋亡。为了证明TGF-β/Smad信号对人胚胎横纹肌肉瘤（RMS）细胞生长和凋亡的影响，采用RNAi介导的Smad4“基因沉默”策略来中断RMS细胞系RD中的内源性TGF-β/Smad信号传导，并且还确定了外源性TGF-β1对细胞生长和凋亡的调节作用。在生理上，TGF-β/Smad信号传导对RD的正常生长至关重要。RNAi对内源性TGF-β/Smad信号传导的中断显著抑制了RD细胞的生长，并显著诱导了RD细胞的凋亡。外源性TGF-β1也抑制了RD细胞的生长，但对凋亡没有影响。它还部分抵消了Smad4沉默在RD细胞中诱导的生长抑制和凋亡。这些发现为TGF-β/Smad信号传导如何调节癌细胞的生长和凋亡提供了新的见解。此外，作为一种强大的工具，shRNA干扰抑制内源性Smad4基因表达，随后调节细胞生长和凋亡，这可能为RMS治疗中合理干预策略的开发提供新的基础。
