Manni A, Wechter R, Grove R, Wei L, Martel J, Demers L
Department of Medicine, Pennsylvania State University College of Medicine, Hershey 17033, USA.
Breast Cancer Res Treat. 1995 Apr;34(1):45-53. doi: 10.1007/BF00666490.
To determine the direct influence of the polyamine (PA) pathway on breast cancer phenotype, we employed a transfection approach to induce overexpression of the PA biosynthetic enzyme ornithine decarboxylase (ODC) in the hormone-responsive MCF-7 breast cancer cell line. Using a modified calcium phosphate method and an ODC cDNA coding for a truncated and more stable enzyme, we were able to achieve a moderate to marked degree of ODC overexpression (up to 150-fold) in a transient transfection system. ODC-overexpressing MCF-7 cells exhibited a selective increase in cellular putrescine content, while the levels of spermidine and spermine remained unaffected. Under defined culture conditions, overexpression of ODC resulted in a consistent but modest increase in [3H]thymidine incorporation into DNA which was similar in the presence and absence of 17-beta-estradiol, TGF-alpha, and IGF-I. In the presence of serum, the effect of ODC overexpression on basal [3H]-thymidine incorporation into DNA was inconsistent, possibly as a result of subtle differences in culture conditions. Overall, our results support the hypothesis that activation of the PA biosynthetic pathway may confer a growth advantage to breast cancer cells.
为了确定多胺（PA）途径对乳腺癌表型的直接影响，我们采用转染方法在激素反应性MCF-7乳腺癌细胞系中诱导PA生物合成酶鸟氨酸脱羧酶（ODC）的过表达。使用改良的磷酸钙方法和编码截短且更稳定酶的ODC cDNA，我们能够在瞬时转染系统中实现中度至显著程度的ODC过表达（高达150倍）。过表达ODC的MCF-7细胞显示细胞内腐胺含量选择性增加，而亚精胺和精胺水平未受影响。在特定培养条件下，ODC的过表达导致[3H]胸苷掺入DNA出现持续但适度的增加，在存在和不存在17-β-雌二醇、转化生长因子-α（TGF-α）和胰岛素样生长因子-I（IGF-I）的情况下情况相似。在有血清存在时，ODC过表达对基础[3H]胸苷掺入DNA的影响不一致，这可能是由于培养条件的细微差异所致。总体而言，我们的结果支持以下假设：PA生物合成途径的激活可能赋予乳腺癌细胞生长优势。
