Saati N, Ravid A, Liberman U A, Koren R
Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel Aviv University, Israel.
In Vitro Cell Dev Biol Anim. 1997 Apr;33(4):310-4. doi: 10.1007/s11626-997-0052-z.
Agents that increase intracellular cAMP (cAMP elevating agents) and 1, 25(OH)2D3 inhibit the proliferation of many cell types. We investigated the combined effect of 1,25(OH)2D3 and cAMP elevating agents on exponentially growing mouse 3T3 fibroblasts. The following cAMP elevating agents were used: theophylline and pentoxyfilline, which inhibit cAMP-dependent phosphodiesterase; prostaglandin E2 which activates adenylate cyclase by a receptor-mediated mechanism; forskolin, which directly stimulates adenylate cyclase; and the cell permeable cAMP analogs 8-bromo cAMP and N6 benzoyl cAMP. 1,25(OH)2D3 and cAMP elevating agents were added to exponentially growing fibroblasts cultured in 96-well microtiter plates and cell number was monitored 3-7 d later. 1,25(OH)2D3 and the cAMP elevating agents as single agents inhibited the growth of the 3T3 cells. The combined treatment of the fibroblasts with 1,25(OH)2D3 and the cAMP elevating agents resulted in an antiproliferative effect that was more than additive. The synergistic interaction depended on the dose of 1,25(OH)2D3 and was apparent already at 10(-8) M of the hormone. The specificity of the effect of 1,25(OH)2D3 was demonstrated by the finding that 24,25-dihydroxyvitamin D3, a vitamin D metabolite with low affinity for the vitamin D receptor, did not affect the antiproliferative effect of cAMP elevating agents. From the synergistic interaction between 1,25(OH)2D3 and the cell permeable cAMP analogs, we infer that the site of interaction between the two signaling pathways is distal to the cAMP generating and degrading machinery.
增加细胞内cAMP的试剂（cAMP升高剂）和1,25(OH)₂D₃可抑制多种细胞类型的增殖。我们研究了1,25(OH)₂D₃和cAMP升高剂对指数生长期小鼠3T3成纤维细胞的联合作用。使用了以下cAMP升高剂：抑制cAMP依赖性磷酸二酯酶的茶碱和己酮可可碱；通过受体介导机制激活腺苷酸环化酶的前列腺素E₂；直接刺激腺苷酸环化酶的福斯可林；以及细胞可渗透的cAMP类似物8-溴cAMP和N⁶苯甲酰cAMP。将1,25(OH)₂D₃和cAMP升高剂添加到在96孔微量滴定板中培养的指数生长期成纤维细胞中，并在3 - 7天后监测细胞数量。1,25(OH)₂D₃和cAMP升高剂作为单一试剂可抑制3T3细胞的生长。用1,25(OH)₂D₃和cAMP升高剂联合处理成纤维细胞产生了一种超过相加效应的抗增殖作用。协同相互作用取决于1,25(OH)₂D₃的剂量，并且在激素浓度为10⁻⁸ M时就已明显。24,25 - 二羟基维生素D₃是一种对维生素D受体亲和力低的维生素D代谢物，它不影响cAMP升高剂的抗增殖作用，这一发现证明了1,25(OH)₂D₃作用的特异性。从1,25(OH)₂D₃与细胞可渗透的cAMP类似物之间的协同相互作用，我们推断这两条信号通路之间的相互作用位点在cAMP产生和降解机制的下游。
