丝裂原活化蛋白激酶磷酸酶5调节人前列腺癌细胞生长及侵袭的信号转导机制研究

Mechanism of the mitogen-activated protein kinase phosphatase-5 regulating the growth and invasion of a human prostate cancer cell line

目的 在高转移性的人前列腺癌细胞 1E8中 ,探讨丝裂原活化蛋白激酶磷酸酶 5(MKP5 )在ATP激活丝裂原活化蛋白激酶 (MAPK)信号通路及相关生物学行为中的作用。方法 构建野生型 pcDL SRα MKP5表达载体 ,稳定转染 1E8细胞并筛选阳性克隆。应用免疫印迹法检测细胞ERK1/ 2和 p38的活化情况。应用生长曲线、体外侵袭实验及软琼脂集落形成实验检测ATP刺激下 ,分别应用MEK抑制剂PD980 5 9及p38抑制剂SB2 0 35 80后各组转染细胞的生物学行为。结果野生型MKP5可明显抑制ATP对 p38通路的激活 ,明显逆转ATP长期刺激下对 1E8细胞的生长抑制作用 ,并明显抑制ATP短期刺激下对 1E8细胞体外侵袭能力的促进作用 ,其作用与SB2 0 35 80相似。PD980 5 9可以部分逆转ATP对转染细胞的体外生长及软琼脂集落形成能力的抑制作用 ,但对ATP短期刺激下对体外侵袭能力的促进作用不明显。结论 在ATP刺激的不同时相里 ,p38、ERK1/ 2通路以不同的方式参与调节肿瘤细胞的生长、侵袭等过程 ,MKP5可通过抑制p38通路的方式参与抑制ATP的这些作用。

Objective To investigate the effects of mitogen-activated protein kinase phosphatase-5 (MKP5) on the biological behaviors of cell and the activation of mitogen-activated protein kinase (MAPK) induced by P2Y purinergic receptor agonist ATP in the prostate cancer cell line 1E8. Methods 1E8 cells were cultured. The recombinant plasmid pcDL-SRα296-MKP5 containing the human wild type MKP5 cDNA and blank vector pcDL-SRα were co-transfected with pcDNA3 vector plasmid into the 1E8 cells respectively to get strong expression clones. RT-PCR was used to detect the expression of MKP5 mRNA. ATP, MEK inhibitor PD 98059, and p38 inhibitor SB 203580 were added into the culture. Then the total protein was extracted, SDS-PAGE and Western blotting were used to detect the activation of p38 and ERK1/2 induced by ATP with phosphospecific antibodies directed against the dually phosphorylated, active forms of p38 and ERK1/2. The in vitro growth curve was drawn, soft agar colony formation test was made, and Matrigel membrane-penetrating experiment was made to test the invasion ability of 1E8 cells. Results The activity of p38 and that of ERK1/2 of the 1E8 cells untreated by ATP were almost undetected. ATP time-dependently stimulated the activities of ERK1/2 and p38 kinases, inhibited the in vitro growth and colony formation on soft agar, and promoted the in vitro invasion of 1E8 cells. MKP5-transfection effectively inhibited the p38 activity induced by ATP and blocked the effects by ATP stimulation on 1E8 cells. The activity of p38 kinase was significantly decreased both in the control and MKP5 transfected cells that were pretreated with SB203580 and then with ATP with an inhibition rates of 83.14% and 58.00% ( P <0.001 and P =0.003). The growth of cells transfected with MKP5 was significantly inhibited ( P <0.001) and further inhibited by addition of ATP. The inhibition of growth of MKP5-tranasfeted cells by ATP could be partially reversed by pretreatment of PD98059 ( P <0.05). The number of cells transfected with MKP5 that penetrated the membrane was significantly less than that of the control cells ( P =0.000 9). ATP increased the penetrating ability of different cells (all P <0.01), and this action was partially inhibited by MKP5 transfetion and addition of SB203580 ( P <0.001), but not by the addition of PD98059. ATP treatment decreased the colony formation on soft agar of different cells, especially of the MKP5 transfected cells ( P <0.001). Such action was partially reversed by SB203580 and PD98059. Conclusion The p38 and ERK1/2 pathways exert different effects on the in vitro growth, invasion and colony formation of 1E8 prostate cancer cells related to ATP. The p38 pathway may be more important in the invasive capability of 1E8 cells. MKP5 plays an important role in the regulation of p38 action.