Kobayashi Ikuo, Jin Long, Ruebel Katharina H, Bayliss Jill M, Hidehiro Oka, Lloyd Ricardo V
Department of Laboratory Medicine and Pathology, Mayo Clinic and Mayo Foundation, Rochester, Minnesota 55901, USA.
Endocrine. 2003 Dec;22(3):285-92. doi: 10.1385/ENDO:22:3:285.
Recent studies have shown that 7B2 and the neuroendocrine- specific proconvertase PC2 have important roles in pituitary cell proliferation and hormone secretion. Studies from our laboratory have also shown that TGFb1 regulates anterior pituitary cell proliferation and hormone secretion. To study the regulation of 7B2 in human pituitary tumors, we used a cell line derived from a human pituitary adenoma (HP75) that has been shown to express 7B2, PC1, PC2, and TGFbeta receptors to analyze the effects of TGFbeta1 and the histone deacetylase inhibitor (HDACI) sodium butyrate (NaB) treatment on 7B2 mRNA expression along with the neuroendocrine-specific proconvertases 1/3 (PC1) and PC2 mRNA and protein expression. RNA was quantified by real-time PCR and proteins were detected by immunohistochemistry and Western blotting. Treatment of cells with 1 mM NaB or 1 nM TGF 1 for 4 d decreased cell proliferation with a concomitant increase in the cell cycle protein p21. Real-time PCR analysis showed a significant increase in 7B2 mRNA after NaB and TGFbeta1 treatment. PC2 mRNA was down regulated by NaB while PC1 mRNA was unchanged. TGFbeta1 stimulated PC1, but not PC2 mRNA levels. Changes in PC1 and PC2 protein were similar to changes in the mRNAs, but the differences were not significant. These results indicated that NaB and TGFbeta1 inhibit pituitary cell proliferation and regulate the expression of 7B2, PC1, and PC2 in a cell culture model of pituitary tumors. Our results also indicate that inhibition of pituitary cell proliferation is associated with increased expression of 7B2 mRNA.
最近的研究表明，7B2和神经内分泌特异性蛋白酶原转化酶PC2在垂体细胞增殖和激素分泌中起重要作用。我们实验室的研究也表明，转化生长因子β1（TGFβ1）调节垂体前叶细胞增殖和激素分泌。为了研究7B2在人类垂体肿瘤中的调节作用，我们使用了一种源自人类垂体腺瘤（HP75）的细胞系，该细胞系已被证明可表达7B2、PC1、PC2和TGFβ受体，以分析TGFβ1和组蛋白脱乙酰酶抑制剂（HDACI）丁酸钠（NaB）处理对7B2 mRNA表达以及神经内分泌特异性蛋白酶原1/3（PC1）和PC2 mRNA及蛋白表达的影响。通过实时定量PCR对RNA进行定量，通过免疫组织化学和蛋白质印迹法检测蛋白质。用1 mM NaB或1 nM TGFβ1处理细胞4天可降低细胞增殖，同时细胞周期蛋白p21增加。实时PCR分析显示，NaB和TGFβ1处理后7B2 mRNA显著增加。NaB使PC2 mRNA下调，而PC1 mRNA不变。TGFβ1刺激PC1 mRNA水平，但不刺激PC2 mRNA水平。PC1和PC2蛋白的变化与mRNA的变化相似，但差异不显著。这些结果表明，在垂体肿瘤细胞培养模型中，NaB和TGFβ1抑制垂体细胞增殖并调节7B2、PC1和PC2的表达。我们的结果还表明，垂体细胞增殖的抑制与7B2 mRNA表达的增加有关。
