Schuller Hildegard M, Al-Wadei Hussein A N, Majidi Mourad
Experimental Oncology Laboratory, Department of Pathobiology, College of Veterinary Medicine, University of Tennessee, Knoxville, Tennessee 37996, USA.
Cancer. 2008 Feb 15;112(4):767-78. doi: 10.1002/cncr.23231.
Pancreatic ductal adenocarcinoma (PDAC) is a leading cause of cancer death. Smoking, diabetes, and pancreatitis are risk factors. It has been shown that the growth of PDAC and pancreatic duct epithelial cells is regulated by beta-adrenoreceptors (beta-ARs). The activity of beta-ARs in the central nervous system is counteracted by gamma-aminobutyric acid (GABA) via GABA B receptor-mediated inhibition of adenylyl cyclase. The aim of the study was to investigate if GABA B R inhibits beta-AR signaling in PDAC and pancreatic duct epithelial cells, thus blocking driving forces of cancer progression, such as cell proliferation and cell migration.
Intracellular cAMP was measured by immunoassays, DNA synthesis by BrdU incorporation assays, activation of ERK1/2 by ERK activation assays, and Western blots and metastatic potential by cell migration assays in the human PDAC cell lines PANC-1 and BXPC-3 and immortalized human pancreatic duct epithelial cells HPDE6-C7. The expression of norepinephrine, PKAR IIalpha, and GABA in PDAC microarrays was assessed by immunohistochemistry. RESULTS.: Stimulation of the GABA B R by GABA or baclofen inhibited isoproterenol-induced cAMP signaling below base levels. ERK1/2 activity in response to isoproterenol was blocked by GABA, an effect enhanced by transient overexpression of the GABA B R and abolished by GABA B R knockdown. DNA synthesis and cell migration were stimulated by isoproterenol, responses blocked by GABA and baclofen. Norepinephrine and PKAR IIalpha were overexpressed while GABA was underexpressed in human PDAC tissue arrays.
The data suggest the stimulation of GABA B R signaling as a novel target for the treatment and prevention of pancreatic cancer.
胰腺导管腺癌（PDAC）是癌症死亡的主要原因。吸烟、糖尿病和胰腺炎是风险因素。研究表明，PDAC和胰腺导管上皮细胞的生长受β-肾上腺素能受体（β-ARs）调节。中枢神经系统中β-ARs的活性被γ-氨基丁酸（GABA）通过GABA B受体介导的腺苷酸环化酶抑制作用所抵消。本研究的目的是调查GABA B R是否抑制PDAC和胰腺导管上皮细胞中的β-AR信号传导，从而阻断癌症进展的驱动因素，如细胞增殖和细胞迁移。
通过免疫测定法测量细胞内cAMP，通过BrdU掺入测定法测量DNA合成，通过ERK激活测定法测量ERK1/2的激活，并通过细胞迁移测定法在人PDAC细胞系PANC-1和BXPC-3以及永生化人胰腺导管上皮细胞HPDE6-C7中进行蛋白质免疫印迹和转移潜能分析。通过免疫组织化学评估PDAC微阵列中去甲肾上腺素、PKAR IIα和GABA的表达。结果：GABA或巴氯芬刺激GABA B R可将异丙肾上腺素诱导的cAMP信号传导抑制至基础水平以下。GABA可阻断异丙肾上腺素诱导的ERK1/2活性，GABA B R的瞬时过表达可增强该效应，而GABA B R敲低可消除该效应。异丙肾上腺素刺激DNA合成和细胞迁移，GABA和巴氯芬可阻断这些反应。在人PDAC组织阵列中，去甲肾上腺素和PKAR IIα过表达，而GABA表达不足。
数据表明刺激GABA B R信号传导是治疗和预防胰腺癌的新靶点。
