p38MAPK信号通路与uPA在乳腺癌细胞及组织中表达的相关性

Correlation of p38 Mitogen-activated Protein Kinase Signal Transduction Pathway to uPA Expression in Breast Cancer

背景与目的:p38MAPK信号通路介导多种转移相关基因表达调控,尿激酶型纤溶酶原激活剂(urokinase-typeplasminogenactivator,uPA)在肿瘤浸润和转移中发挥着重要作用。本实验研究人乳腺癌组织中3种信号分子p-p38、p-Akt、p-Erk及uPA表达与临床病理特征的关系,并分析它们与uPA表达的相关性,探讨p38MAPK通路对乳腺癌uPA蛋白表达的影响,分析p-p38和uPA表达与乳腺癌预后的关系。方法:应用免疫组织化学(SP)法检测p-p38、p-Akt、p-Erk和uPA在60例乳腺癌组织中的表达。Westernblot检测人乳腺癌细胞MDA-MB-231及MCF-7中p-p38及uPA蛋白表达及用p38MAPK特异性抑制剂SB203580阻断p38MAPK信号通路后uPA蛋白表达水平的变化。结果:p-p38、p-Akt、p-Erk、uPA蛋白在乳腺癌组织中表达阳性率分别为56.7%、95.0%、93.3%、60.0%。p-p38与uPA表达存在正相关(r=0.316,P<0.05),并与乳腺癌的TNM分期及淋巴结转移状况相关(P<0.05),而与患者年龄、肿瘤大小无明显相关性(P>0.05)。p-Akt、p-Erk与uPA表达无明显相关性,p-Akt和p-Erk蛋白表达与乳腺癌的淋巴结转移有关(P<0.05)而与患者年龄、肿瘤大小、TNM分期均无明显关系(P>0.05)。乳腺癌细胞MDA-MB-231中p-p38及uPA蛋白表达水平高于MCF-7。用SB203580阻断p38MAPK通路可降低uPA蛋白表达水平,且随着SB203580浓度升高uPA表达水平逐渐降低。乳腺癌中p-p38和uPA蛋白的表达与肿瘤的预后显著相关(分别为log-rank=4.98、5.40,P=0.0256、0.0201)。结论:p38MAPK信号通路可能通过上调uPA的表达促进乳腺癌的恶性进展,p38MAPK信号通路可能是乳腺癌侵袭和转移的重要途径,p-p38和uPA的表达可辅助用于乳腺癌的预后评估。

BACKGROUND ＆ OBJECTIVE： p38 mitogen-activated protein kinase （p38MAPK） signal transduction pathway regulates the expression of various metastasis-related genes. Urokinase-type plasminogen activator （uPA） plays an important role in cancer invasion and metastasis. This study was to explore the correlation of p38MAPK signal transduction pathway to uPA expression in breast cancer. METHODS： SP immunohistochemistry was used to test the expression of p-p38, p-Akt, p-Erk, and uPA in 60 specimens of breast cancer. Western blot was used to detect the protein levels of p-p38 and uPA in breast cancer MDA-MB-231 and MCF-7 cells and the protein level of uPA in MDA-MB-231 cells after blocking p38MAPK signal transduction pathway by SB203580, a specific inhibitor of p38MAPK. The correlations of p-p38, p- Akt, p-Erk, and uPA expression to the clinicopathologic characteristics of breast cancer, and the correlations of p-p38, p-Akt, and p-Erk expression to uPA expression were analyzed. The mechanism of p38MAPK signal transduction pathway regulating the protein expression of uPA in breast cancer cells was investigated. The correlation of p-p38 and uPA expression to prognosis of breast cancer was analyzed. RESULTS. The positive rates of p- p38, p-Akt, p-Erk, and uPA proteins in breast cancer tissues were 56.7%, 95.0%, 93.3%, and 60.0%, respectively. The expression of p-p38 was positively correlated to the expression of uPA （r=0.316, P〈0.05）, while the expression of p-Akt and p-Erk was not related to uPA expression. The expression of p-p38 and uPA was correlated to lymph node metastasis and TNM stage （P〈0.05）, but not to patients＇ age and tumor size （P〉0.05）. The expression of p-Akt and p-Erk were correlated to lymph node metastasis （P〈 0.05）, but not to TNM stage, patients＇ age, and tumor size （P〉0.05）. The protein levels of p-p38 and uPA in MDA-MB-231 cells were higher than that in MCF-7 cells. SB203580 concentration-dependently inhibited p38MAPK pathway and induced uPA protein expression. The expression of p-p38 and uPA was negatively correlated to prognosis of breast cancer （log-rank=4.98, 5.40, P= 0.026, 0.020）. CONCLUSIONS： p38MAPK signal transduction pathway might improve breast cancer progression by up-regulating uPA expression, and might be an important route in invasion and metastasis of breast cancer, p-p38 and uPA might help to evaluate prognosis of breast cancer.