Li J J, Oberley L W, St Clair D K, Ridnour L A, Oberley T D
Radiation Research Laboratory, University of Iowa, Iowa City 52242, USA.
Oncogene. 1995 May 18;10(10):1989-2000.
Human manganese containing superoxide dismutase (MnSOD) cDNA was transfected into a human breast cancer cell line (MCF-7) in order to examine the effect of increased functional MnSOD on the cellular phenotype. A MnSOD-overexpressing clone was compared to control vector-transfected cells and to wild type MCF-7 cells. Southern blotting indicated incorporation of MnSOD cDNA into genomic DNA in the MnSOD overexpressing cell line. The MnSOD overexpressing cell line showed a 5.7-fold increase in MnSOD activity compared to wild type MCF-7 cells. Similar increases in MnSOD immunoreactive protein and mRNA levels were observed by Western and Northern blotting as well as using RT-PCR. The plating efficiency of cells grown in different concentrations of serum (1 to 20%) was decreased in the MnSOD overexpressing cell line. The clonogenic fraction in soft agar culture was also decreased after MnSOD cDNA transfection. When inoculated in nude mice, tumor growth was markedly inhibited in MnSOD overexpressing cells compared to wild type MCF-7 cells or plasmid control cells. These results support the hypothesis that increased MnSOD expression suppresses the malignant phenotype of human breast cancer cells and suggests that the MnSOD gene is a tumor suppressor gene in human breast cancer.
为了研究功能性超氧化物歧化酶（MnSOD）增加对细胞表型的影响，将人含锰超氧化物歧化酶（MnSOD）cDNA转染到人乳腺癌细胞系（MCF-7）中。将过表达MnSOD的克隆与对照载体转染细胞以及野生型MCF-7细胞进行比较。Southern印迹表明MnSOD cDNA已整合到过表达MnSOD的细胞系的基因组DNA中。与野生型MCF-7细胞相比，过表达MnSOD的细胞系MnSOD活性增加了5.7倍。通过Western和Northern印迹以及使用RT-PCR观察到MnSOD免疫反应性蛋白和mRNA水平有类似的增加。在不同血清浓度（1%至20%）下生长的过表达MnSOD的细胞系细胞接种效率降低。MnSOD cDNA转染后软琼脂培养中的克隆形成率也降低。当接种到裸鼠中时，与野生型MCF-7细胞或质粒对照细胞相比，过表达MnSOD的细胞中肿瘤生长明显受到抑制。这些结果支持以下假设：MnSOD表达增加可抑制人乳腺癌细胞的恶性表型，并表明MnSOD基因是人类乳腺癌中的一种肿瘤抑制基因。
