Fernández-Martínez Ana B, Carmena María J, Bajo Ana M, Vacas Eva, Sánchez-Chapado Manuel, Prieto Juan C
Department of Systems Biology, Unit of Biochemistry and Molecular Biology, University of Alcalá, 28871 Alcalá de Henares, Spain.
Department of Surgery and Medical and Social Sciences, University of Alcalá, 28871 Alcalá de Henares, Spain; Department of Urology, Príncipe de Asturias Hospital, 28871 Alcalá de Henares, Spain.
Cell Signal. 2015 Feb;27(2):236-44. doi: 10.1016/j.cellsig.2014.11.005. Epub 2014 Nov 15.
The nuclear factor κB (NF-κB) is a powerful activator of angiogenesis, invasion and metastasis. Transactivation and nuclear localisation of NF-κB is an index of recurrence in prostate cancer. Vasoactive intestinal peptide (VIP) exerts similar effects in prostate cancer models involving increased expression of vascular endothelial growth factor (VEGF) and cyclooxygenase-2 (COX-2) which are related to NF-κB transactivation. Here we studied differential mechanisms of VIP-induced NF-κB transactivation in non-tumour RWPE-1 and tumour LNCaP and PC3 human prostate epithelial cells. Immunofluorescence studies showed that VIP increases translocation of the p50 subunit of NF-κB1 to the nucleus, an effect that was inhibited by curcumin. The signalling transduction pathways involved are different depending on cell transformation degree. In control cells (RWPE1), the effect is mediated by protein kinase A (PKA) activation and does not implicate extracellular signal-regulated kinase (ERK) or phosphoinositide 3-kinase (PI3-K) pathways whereas the opposite is true in tumour LNCaP and PC3 cells. Exchange protein directly activated by cAMP (EPAC) pathway is involved in transformed cells but not in control cells. Curcumin blocks the activating effect of VIP on COX-2 promoter/prostaglandin E2 (PGE2) production and VEGF expression and secretion. The study incorporates direct observation on COX-2 promoter and suggests that VIP effect on VEGF may be indirectly mediated by PGE2 after being synthesised by COX-2, thus amplifying the initial signal. We show that the signalling involved in VIP effects on VEGF is cAMP/PKA in non-tumour cells and cAMP/EPAC/ERK/PI3K in tumour cells which coincides with pathways mediating p50 nuclear translocation. Thus, VIP appears to use different pathways for NF-κB1 (p50) transactivation in prostate epithelial cells depending on whether they are transformed or not. Transformed cells depend on pro-survival and pro-proliferative signalling pathways involving ERK, PI3-K and cAMP/EPAC which supports the potential therapeutic value of these targets in prostate cancer.
核因子κB（NF-κB）是血管生成、侵袭和转移的强大激活剂。NF-κB的反式激活和核定位是前列腺癌复发的一个指标。血管活性肠肽（VIP）在前列腺癌模型中发挥类似作用，涉及血管内皮生长因子（VEGF）和环氧合酶-2（COX-2）表达增加，而这两者与NF-κB反式激活相关。在此，我们研究了VIP诱导的NF-κB反式激活在非肿瘤性RWPE-1细胞以及肿瘤性LNCaP和PC3人前列腺上皮细胞中的不同机制。免疫荧光研究表明，VIP增加NF-κB1的p50亚基向细胞核的转位，姜黄素可抑制这一效应。所涉及的信号转导途径因细胞转化程度而异。在对照细胞（RWPE1）中，该效应由蛋白激酶A（PKA）激活介导，不涉及细胞外信号调节激酶（ERK）或磷酸肌醇3激酶（PI3-K）途径，而在肿瘤性LNCaP和PC3细胞中情况则相反。cAMP直接激活的交换蛋白（EPAC）途径参与转化细胞，但不参与对照细胞。姜黄素可阻断VIP对COX-2启动子/前列腺素E2（PGE2）产生以及VEGF表达和分泌的激活作用。该研究对COX-2启动子进行了直接观察，并表明VIP对VEGF的作用可能在COX-2合成PGE2后由PGE2间接介导，从而放大初始信号。我们表明，VIP对VEGF作用所涉及的信号在非肿瘤细胞中为cAMP/PKA，在肿瘤细胞中为cAMP/EPAC/ERK/PI3K，这与介导p50核转位的途径一致。因此，VIP似乎根据前列腺上皮细胞是否转化而使用不同途径进行NF-κB1（p50）的反式激活。转化细胞依赖于涉及ERK、PI3-K和cAMP/EPAC的促生存和促增殖信号转导途径，这支持了这些靶点在前列腺癌中的潜在治疗价值。
