糖皮质激素抑制结肠癌细胞增殖和侵袭的作用机制

本研究目的是为了证实地塞米松对结肠癌LoVo细胞增殖的抑制作用,并阐明其中的分子机制。LoVo细胞经不同浓度梯度地塞米松干预,再加入TGF-β1受体抑制剂SB431542阻断TGF-β1信号传导途径,通过MTS分析各组细胞增殖情况,借助Hoechst 33342和Annexin V/PI染色法检测细胞凋亡率;结合Western blotting对TGF-β1、Smad2和caspase-3蛋白表达情况的检测结果,分析地塞米松诱导结肠癌LoVo细胞凋亡的作用机理。LoVo细胞在1.0 mmol/L和10.0 mmol/L地塞米松干预48 h后,细胞增殖率与对照组相比分别降低32%(p<0.01)和47%(p<0.001),2组细胞凋亡率分别为28%和36%(p<0.001)。Western blotting结果显示,与对照组相比,地塞米松以浓度依赖性方式显著上调LoVo细胞TGF-β1、Smad2和Cleavedcaspase-3蛋白水平(p<0.01),而TGF-β1受体抑制剂SB431542明显下调TGF-β1、Smad2和Cleaved-capase-3蛋白表达(p<0.05)。流式细胞术检测结果表明,SB431542+地塞米松干预组与地塞米松处理组LoVo细胞凋亡率分别为8%和23%(p<0.001)。地塞米松可显著诱导LoVo细胞凋亡,而SB431542能够挽救这一过程,这表明,地塞米松通过TGF-β1/Smad2通路诱导LoVo细胞凋亡。

Mechanism of Glucocorticoids Inhibiting Proliferation and Invasion of Colon Cancer Cells

The aim of this study was to confirm the inhibitory effect of dexamethasone on the proliferation of colon cancer Lo Vo cells and to elucidate its molecular mechanism. LoVo cells were treated with different concentrations of dexamethasone, and then TGF-β1 receptor inhibitor SB431542 was added to block TGF-β1 signaling pathway. Cell proliferation was analyzed by MTS. The apoptosis rate was detected by Hoechst 33342 and Annexin V/PI staining;The expression of TGF-β1, Smad2 and caspase-3 protein was detected by Western blotting. Finally,the mechanism of dexamethasone-induced apoptosis in colon cancer LoVo cells was analyzed. After LoVo cells were treated with 1.0 mmol/L and 10.0 mmol/L dexamethasone for 48 h, the cell proliferation rate was reduced by32%(p<0.01) and 47%(p<0.001) compared with the control group. The apoptosis rates of the two groups were 28% and 36%, respectively(p<0.001). Western blotting results showed that compared with the control group, dexamethasone significantly up-regulated TGF-β1, Smad2 and Cleaved-caspase-3 protein levels in LoVo cells in a concentration-dependent manner(p<0.01), while TGF-β1 receptor inhibitors SB431542 significantly down-regulated the expression of TGF-β1, Smad2 and Cleaved-caspase-3(p<0.05). The results of flow cytometry showed that the apo-ptosis rate of LOVO cells in SB431542 +dexamethasone intervention group and dexamethasone treatment group was 8% and 23%, respectively(p<0.001). Dexamethasone can significantly induce apoptosis of LoVo cells,and SB431542 can save this process. This indicates that dexamethasone induces apoptosis of LoVo cells through the TGF-β1/Smad2 pathway.