Peirce Susan K, Chen Wen Y
Department of Genetics and Biochemistry, Clemson University, Clemson, SC 29630, USA.
Oncogene. 2004 Feb 12;23(6):1248-55. doi: 10.1038/sj.onc.1207245.
To gain insight into the molecular mechanisms involved in human prolactin receptor antagonist (hPRL-G129R)-induced apoptosis, we used real-time reverse transcription-polymerase chain reaction to measure bax and bcl-2 gene expression in 11 human breast cancer cell lines following treatment with hPRL and hPRL-G129R. We also measured bax and bcl-2 gene expression in the mammary glands of transgenic mice expressing hPRL or hPRL-G129R. A time-course study of hPRL and antagonist treatment in T-47D cells indicated changing bax/bcl-2 mRNA ratios beginning at 24 h. We found that bax/bcl-2 mRNA ratios were significantly elevated in seven of the 11 hPRL-G129R-treated cell lines, as well as in the hPRL-G129R transgenic mice. To confirm these results, Bax and Bcl-2 proteins were analysed by Western blot methods in mammary gland tissue homogenates of transgenic mice. Bax/Bcl-2 ratios were highest in the 6-month group of hPRL-G129R transgenics, and lowest in the 6-month group of hPRL transgenics. We expanded our findings by examining the release of a downstream Bax-induced protein, cytochrome c, a hallmark protein of apoptosis, in transgenic mice. Again, cytochrome c levels were highest in the 6-month hPRL-G129R transgenic group. Thus, hPRL-G129R-induced breast cancer cell and/or mammary gland apoptosis is mediated, at least in part, through the regulation of Bax and Bcl-2 gene expression.
为深入了解人催乳素受体拮抗剂（hPRL-G129R）诱导细胞凋亡的分子机制，我们采用实时逆转录-聚合酶链反应来检测11种人乳腺癌细胞系在用hPRL和hPRL-G129R处理后的bax和bcl-2基因表达。我们还检测了表达hPRL或hPRL-G129R的转基因小鼠乳腺中的bax和bcl-2基因表达。对T-47D细胞进行hPRL和拮抗剂处理的时间进程研究表明，从24小时开始bax/bcl-2 mRNA比率发生变化。我们发现，在11种经hPRL-G129R处理的细胞系中的7种以及hPRL-G129R转基因小鼠中，bax/bcl-2 mRNA比率显著升高。为证实这些结果，通过蛋白质免疫印迹法分析了转基因小鼠乳腺组织匀浆中的Bax和Bcl-2蛋白。Bax/Bcl-2比率在hPRL-G129R转基因小鼠的6个月组中最高，而在hPRL转基因小鼠的6个月组中最低。我们通过检测转基因小鼠中一种下游Bax诱导蛋白——细胞色素c（细胞凋亡的标志性蛋白）的释放来扩展我们的研究结果。同样，细胞色素c水平在6个月的hPRL-G129R转基因组中最高。因此，hPRL-G129R诱导的乳腺癌细胞和/或乳腺细胞凋亡至少部分是通过对Bax和Bcl-2基因表达的调控介导的。
