Chigurupati Srinivasulu, Kulkarni Trupti, Thomas Shibu, Shah Girish
Department of Pharmacology, University of Louisiana School of Pharmacy, College of Health Sciences, Monroe, Louisiana 71209, USA.
Cancer Res. 2005 Sep 15;65(18):8519-29. doi: 10.1158/0008-5472.CAN-05-0848.
Although a strong correlation between neuroendocrine differentiation and angiogenesis of prostate cancer has been reported, no mechanistic link between the two events has been established. Because neuropeptide calcitonin is secreted by prostate tumors and endothelial cells are known to express calcitonin receptor-like receptor, we examined the potential action of calcitonin on endothelial cells. The presence of calcitonin receptor, calcitonin receptor-like receptor, and receptor activity-modifying proteins in human microvessel endothelial-1 cells was tested by reverse transcriptase-PCR (RT-PCR). The proangiogenic action of calcitonin was examined in several in vitro models of angiogenesis using HMEC-1 cells and also in vivo using dorsal skinfold assays. Calcitonin expression of PC-3M cells was modulated, and its effect on angiogenesis was examined in in vitro as well as in vivo models. The results of RT-PCR and radioligand receptor assays showed the presence of functional calcitonin receptor in HMEC-1 cells. Calcitonin stimulated all phases of angiogenesis through the calcitonin receptor, but its effect on tube morphogenesis by endothelial cells occurred at the concentration of the Kd of calcitonin receptor. Silencing of calcitonin receptor expression in HMEC-1 cells abolished calcitonin-induced tube formation. Vascular endothelial growth factor antibodies attenuated but did not abolish calcitonin-induced tube morphogenesis. PC-3M prostate cancer cells induced angiogenesis in in vivo and in vitro models. Overexpression of calcitonin in PC-3M cells increased their angiogenic activity, whereas the silencing of calcitonin expression abolished it. These results show that prostate tumor-derived calcitonin may play an important role in prostate tumor growth by regulating intratumoral vascularization.
尽管已有报道称前列腺癌的神经内分泌分化与血管生成之间存在很强的相关性，但尚未确定这两个事件之间的机制联系。由于前列腺肿瘤会分泌神经肽降钙素，且已知内皮细胞表达降钙素受体样受体，因此我们研究了降钙素对内皮细胞的潜在作用。通过逆转录聚合酶链反应（RT-PCR）检测人微血管内皮-1细胞中降钙素受体、降钙素受体样受体和受体活性修饰蛋白的存在情况。使用HMEC-1细胞在几种体外血管生成模型中以及在体内使用背部皮褶试验研究了降钙素的促血管生成作用。调节PC-3M细胞的降钙素表达，并在体外和体内模型中研究其对血管生成的影响。RT-PCR和放射性配体受体分析结果显示HMEC-1细胞中存在功能性降钙素受体。降钙素通过降钙素受体刺激血管生成的各个阶段，但其对内皮细胞管形态发生的影响发生在降钙素受体的Kd浓度下。HMEC-1细胞中降钙素受体表达的沉默消除了降钙素诱导的管形成。血管内皮生长因子抗体减弱但并未消除降钙素诱导的管形态发生。PC-3M前列腺癌细胞在体内和体外模型中诱导血管生成。PC-3M细胞中降钙素的过表达增加了它们的血管生成活性，而降钙素表达的沉默则消除了这种活性。这些结果表明，前列腺肿瘤来源的降钙素可能通过调节肿瘤内血管形成在前列腺肿瘤生长中发挥重要作用。
