目的：探讨黑素瘤相关抗原-A9（melanoma-associated antigen，MAGE-A9）对人乳腺癌细胞中P53转录活性及功能的影响。 方法：通过LipofectamineTM 2000体外转染质粒pcDNA3.0、pcDNA3.0-p53、pCMV6-MAGE-A9 和pcDNA3.0-p53/MAGE-A9至人乳腺癌MDA-MB-231细胞，RT-PCR和Western blotting检测细胞中 p21WAF1 mRNA和蛋白的表达，荧光素酶报告基因分析检测细胞中 p21WAF1 启动子介导的荧光素酶表达活性，MTT法检测转染不同质粒对MDA-MB-231细胞增殖的影响。 结果： 转染pcDNA3.0-p53/MAGE-A9组MDA-MB-231细胞中 p21WAF1 mRNA和蛋白表达水平均明显低于pcDNA3.0-p53组\[(0.15±0.01) vs (0.18±0.02)，(0.03±0.00) vs (0.06±0.01)；均P<0.05\]。转染pcDNA3.0-p53质粒可以增强MDA-MB-231细胞中 p21WAF1 启动子介导的荧光素酶的表达\[(58.56±3.47) vs (1.00±0.12)，P<0.01\]，转染pcDNA3.0-p53/MAGE-A9后，MDA-MB-231细胞中 p21WAF1 启动子介导的荧光素酶的表达较转染pcDNA3.0-p53组明显降低\[(22.02±4.91) vs (58.56±3.47)，P<005\]。与pcDNA3.0组相比，pcDNA3.0-p53组MDA-MB-231细胞增殖率明显明显降低\[(228.89±2239)% vs (337.23± 23.67)%，P<0.05\]；而pcDNA3.0-p53/MAGE-A9组MDA-MB-231细胞增殖率明显高于pcDNA3.0-p53组\[(291.51±591)% vs (228.89±22.39)%，P<0.05\]。 结论： MAGE-A9可抑制MDA-MB-231细胞中P53的转录活性及细胞增殖。

Objective : To explore the effect of melanoma-associated antigen (MAGE)-A9 on the transcriptional activity and the function of P53. Methods: Plasmids pcDNA3.0, pcDNA3.0-p53 and pCMV6-MAGE-A9 were transfeced in vitro into human breast cancer MDA-MB-231 cells using LipofectamineTM2000. The expressions of p21WAF1 mRNA and protein in MDA-MB-231 cells were analyzed by RT-PCR and Western blotting. Luciferase reporter assay was performed to determine the luciferase activity induced by p21WAF1 promoter in MDA-MB-231 cells. MTT assay were adopted to explore the effect of different plasmids on the cell proliferation. Results: The expression of p21WAF1 both in mRNA and protein levels was decreased in pcDNA3.0-p53/MAGE-A9 group, compared with pcDNA3.0-p53 group (\[0.15±0.01\] vs \[0.18±002\], \[0.03±0.00\] vs \[0.06±0.01\], P<0.05). The luciferase activity induced by p21WAF1 promoter was remarkably increased in MDA-MB-231 cells transfected with plasmid pcDNA3.0-p53 (\[58.56±3.47\] vs \[1.00±012\], P<001). After transfected with pcDNA3.0-p53/MAGE-A9, the luciferase activity induced by p21WAF1 promoter in MDA-MB-231 cells was significantly reduced compared with that in pcDNA3.0-p53 group (\[22.02±4.91\] vs \[58.56±3.47\], P<005). Compared with pcDNA3.0 group, the proliferation rate were significantly decreased in pcDNA3.0-p53 group (\[228.89±22.39\]% vs \[337.23±23.67\]%, P<0.05), while in pcDNA3.0-p53/MAGE-A9 group, it was significantly higher than that in pcDNA3.0-p53 group (\[291.51±5.91\]% vs \[228.89±22.39\]%, P<0.05). Conclusion: MAGE-A9 can inhibit the transcriptional activity of P53 and proliferation of MDA-MB-231 cells.

河北省卫生厅科研基金资助项目（No. 20100120）；河北省自然科学基金资助项目（No. H2012206077）