Lin Cheng-Wei, Yang Liang-Yo, Shen Shing-Chuan, Chen Yen-Chou
Graduate Institute of Pharmacy, School of Pharmacy, Taipei Medical University, Taipei, Taiwan.
J Cell Physiol. 2007 Sep;212(3):666-74. doi: 10.1002/jcp.21061.
Induction of 17beta-estradiol (E2) and insulin-like growth factor-I (IGF-I) has been detected in breast carcinoma, however the interaction between E2 and IGF-I in the proliferation of breast carcinoma cells is still unclear. In the present study, we found that IGF-I enhances the E2-induced proliferation in MCF-7 human breast carcinoma cells in accordance with stimulation of colony formation via a soft agar assay. Activation of insulin receptor substrate-1 (IRS-1) protein and extracellular signal-related kinases (ERKs) and c-Jun N-terminal kinases (JNKs), but not p38 mitogen-activated protein kinase (MAPK), via phosphorylation induction was detected in MCF-7 cells treated with IGF-I plus E2 (E2/IGF-I). E2/IGF-I-induced proliferation was blocked by chemical inhibitors of ERKs (PD98059) and JNKs (SP600125). An increase in the expression of c-Jun protein was detected in E2/IGF-I-treated MCF-7 cells, and this was inhibited by PD98059 and SP600125. Transfection of the dominant negative MEKK and JNK plasmids significantly reduced E2/IGF-I-induced proliferation with suppression of c-Jun protein expression. An increase in peroxide production was detected in E2/IGF-I-treated cells, and N-acetyl-L-cysteine (NAC) and Tiron (TIR) addition significantly inhibited E2/IGF-I-induced cell proliferation with blocking of the phosphorylation of ERKs and JNKs, and the expression of c-Jun protein. Additionally, 3-OH flavone, baicalein, and quercetin showed effective inhibitory activities against E2/IGF-I-induced proliferation through suppressing proliferative events such as phosphorylation of IRS-1, ERKs, and JNKs proteins, and induction of c-Jun protein and colony formation. These results indicate that IGF-I interacts with E2 to promote the proliferation of breast carcinoma cells via ROS-dependent MAPK activation and c-Jun protein expression. The structure-related inhibition of E2/IGF-I-induced proliferative events by flavonoids is elucidated.
在乳腺癌中已检测到17β-雌二醇（E2）和胰岛素样生长因子-I（IGF-I）的诱导，但E2与IGF-I在乳腺癌细胞增殖中的相互作用仍不清楚。在本研究中，我们发现IGF-I通过软琼脂试验刺激集落形成，增强了E2诱导的MCF-7人乳腺癌细胞增殖。在用IGF-I加E2（E2/IGF-I）处理的MCF-7细胞中，检测到胰岛素受体底物-1（IRS-1）蛋白、细胞外信号相关激酶（ERK）和c-Jun氨基末端激酶（JNK）通过磷酸化诱导而激活，但未检测到p38丝裂原活化蛋白激酶（MAPK）激活。E2/IGF-I诱导的增殖被ERK（PD98059）和JNK（SP600125）的化学抑制剂阻断。在用E2/IGF-I处理的MCF-7细胞中检测到c-Jun蛋白表达增加，而PD98059和SP600125可抑制这种增加。转染显性负性MEKK和JNK质粒可显著降低E2/IGF-I诱导的增殖，并抑制c-Jun蛋白表达。在用E2/IGF-I处理的细胞中检测到过氧化物生成增加，添加N-乙酰-L-半胱氨酸（NAC）和钛铁试剂（TIR）可显著抑制E2/IGF-I诱导的细胞增殖，同时阻断ERK和JNK的磷酸化以及c-Jun蛋白的表达。此外，3-羟基黄酮、黄芩素和槲皮素通过抑制增殖事件，如IRS-1、ERK和JNK蛋白的磷酸化以及c-Jun蛋白的诱导和集落形成，对E2/IGF-I诱导的增殖显示出有效的抑制活性。这些结果表明，IGF-I与E2相互作用，通过活性氧（ROS）依赖的MAPK激活和c-Jun蛋白表达促进乳腺癌细胞增殖。阐明了黄酮类化合物对E2/IGF-I诱导的增殖事件的结构相关抑制作用。
