Evans K D, Oberbauer A M
Department of Animal Science, University of California, One Shields Ave., Davis, CA 95616, USA.
Open Orthop J. 2009 Oct 1;3:83-8. doi: 10.2174/1874325000903010083.
Bisphosphonates decrease chondrocyte turnover at the growth plate and impact bone growth. Likewise vascular endothelial growth factor (VEGF) plays an important role in endochondral bone elongation by influencing chondrocyte turnover at the growth plate. To investigate whether the action of bisphosphonate on the growth plate works through VEGF, VEGF protein expression and isoform transcription in endochondral chondrocytes isolated from growing mice and treated with a clinically used bisphosphonate, alendronate, were assessed. Alendronate at 10microM and 100microM concentrations decreased secreted VEGF protein expression but not cell associated protein. Bisphosphonates are known to inhibit the mevalonate intracellular signaling pathway used by VEGF. Addition of the mevalonate pathway intermediates farnesol (FOH) and geranylgeraniol (GGOH) interacted with the low concentration of alendronate to further decrease secreted VEGF protein whereas FOH partially restored VEGF protein secretion when combined with the high alendronate. Similar to the protein data, the addition of alendronate decreased VEGF mRNA isoforms. VEGF mRNA levels were rescued by the GGOH mevalonate pathway intermediate at the low alendronate dose whereas neither intermediate consistently restored the VEGF mRNA levels at the high alendronate dose. Thus, the bisphophonate alendronate impairs growth plate chondrocyte turnover by down-regulating the secreted forms of VEGF mRNA and protein by inhibiting the mevalonate pathway.
双膦酸盐可降低生长板处软骨细胞的更新率，并影响骨骼生长。同样，血管内皮生长因子（VEGF）通过影响生长板处软骨细胞的更新率，在软骨内骨延长过程中发挥重要作用。为了研究双膦酸盐对生长板的作用是否通过VEGF起作用，我们评估了从生长小鼠分离并经临床使用的双膦酸盐阿仑膦酸钠处理的软骨内软骨细胞中VEGF蛋白表达和异构体转录情况。10μM和100μM浓度的阿仑膦酸钠可降低分泌型VEGF蛋白表达，但不影响细胞相关蛋白。已知双膦酸盐可抑制VEGF使用的甲羟戊酸细胞内信号通路。添加甲羟戊酸途径中间体法尼醇（FOH）和香叶基香叶醇（GGOH）与低浓度阿仑膦酸钠相互作用，可进一步降低分泌型VEGF蛋白，而FOH与高浓度阿仑膦酸钠联合使用时可部分恢复VEGF蛋白分泌。与蛋白质数据相似，添加阿仑膦酸钠可降低VEGF mRNA异构体。低剂量阿仑膦酸钠时，GGOH甲羟戊酸途径中间体可挽救VEGF mRNA水平，而在高剂量阿仑膦酸钠时，两种中间体均不能持续恢复VEGF mRNA水平。因此，双膦酸盐阿仑膦酸钠通过抑制甲羟戊酸途径下调VEGF mRNA和蛋白的分泌形式，从而损害生长板软骨细胞的更新率。
