Law P Y, McGinn T M, Campbell K M, Erickson L E, Loh H H
Department of Pharmacology, Medical School, University of Minnesota, Minneapolis 55455, USA.
Mol Pharmacol. 1997 Jan;51(1):152-60. doi: 10.1124/mol.51.1.152.
Activation by opioid receptors of cell proliferation was examined with fibroblast cell lines stably expressing either delta-opioid or mu-opioid receptors. Addition of [D-Ala2, D-Leu5]-enkephalin or [D-Pen2,D-Pen5]-enkephalin to Chinese hamster ovary (CHO) cells transfected with delta-opioid receptor cDNA resulted in an agonist concentration-dependent potentiation of fetal calf serum (FCS)-stimulated cell proliferation. This potentiation by delta-opioid agonists was antagonized by naloxone and was not observed with the kappa-opioid receptor selective agonist U50,488 or the mu-opioid receptor selective agonist [D-Ala2,N-MePhe4, Gly-ol5]-enkephalin. This delta-opioid agonist effect was not observed at FCS concentrations > 0.1% and could be blocked by pretreating cells with pertussis toxin, indicating that Gi/Go were involved in this action. In addition, delta-opioid agonists could potentiate CHO cell proliferation stimulated by those growth factors that are mediated by tyrosine kinase receptors (i.e., insulin, insulin-like growth factor 1, and fibroblast-derived growth factor b). This delta-opioid agonist potentiation of growth apparently was dependent on the level of delta-opioid receptors that were expressed and had cell-line selectivity. Activation of delta-opioid receptors expressed in Rat-1 or NIH3T3 fibroblast did not result in a modulation of the cell growth induced by FCS or by growth factors. Interestingly, in CHO cells transfected with mu-opioid receptor cDNA, activation with agonists did not produce a potentiation of FCS-stimulated proliferation. This lack of mu-opioid receptor effect was not due to the differences among CHO clones. In a CHO cell line transfected with both delta-opioid receptor cDNA and mu-opioid receptor cDNA, activation of delta-but not mu-opioid receptors resulted in a potentiation of growth. These data suggest that delta- and mu-opioid receptors in CHO cells activate similar but divergent second messenger pathways, resulting in the differential regulation of cell growth.
利用稳定表达δ-阿片受体或μ-阿片受体的成纤维细胞系，研究了阿片受体对细胞增殖的激活作用。向转染了δ-阿片受体cDNA的中国仓鼠卵巢（CHO）细胞中添加[D-Ala2, D-Leu5]-脑啡肽或[D-Pen2,D-Pen5]-脑啡肽，会导致胎牛血清（FCS）刺激的细胞增殖呈激动剂浓度依赖性增强。δ-阿片激动剂的这种增强作用可被纳洛酮拮抗，而κ-阿片受体选择性激动剂U50,488或μ-阿片受体选择性激动剂[D-Ala2,N-MePhe4, Gly-ol5]-脑啡肽则未观察到这种作用。在FCS浓度>0.1%时未观察到这种δ-阿片激动剂效应，且用百日咳毒素预处理细胞可阻断该效应，表明Gi/Go参与了这一作用。此外，δ-阿片激动剂可增强由酪氨酸激酶受体介导的生长因子（即胰岛素、胰岛素样生长因子1和成纤维细胞衍生生长因子b）刺激的CHO细胞增殖。这种δ-阿片激动剂对生长的增强作用显然取决于所表达的δ-阿片受体水平，并具有细胞系选择性。在Rat-1或NIH3T3成纤维细胞中表达的δ-阿片受体的激活并未导致FCS或生长因子诱导的细胞生长调节。有趣的是，在转染了μ-阿片受体cDNA的CHO细胞中，激动剂激活并未产生FCS刺激的增殖增强作用。这种μ-阿片受体效应的缺乏并非由于CHO克隆之间的差异。在同时转染了δ-阿片受体cDNA和μ-阿片受体cDNA的CHO细胞系中，δ-而非μ-阿片受体的激活导致了生长增强。这些数据表明，CHO细胞中的δ-和μ-阿片受体激活了相似但不同的第二信使途径，导致细胞生长的差异调节。
