CCAAT 增强子结合蛋白 β 通过甲基化雌激素受体 β 促进前列腺癌肿瘤生长和抑制细胞凋亡。

CCAAT enhancer binding protein β promotes tumor growth and inhibits apoptosis in prostate cancer by methylating estrogen receptor β.

出版信息

Neoplasma. 2018;65(1):34-41. doi: 10.4149/neo_2018_161205N620.

DOI:10.4149/neo_2018_161205N620

Abstract

The CCAAT enhancer binding protein β (C/EBPβ) is overexpressed at late stages in carcinogenesis of prostate cancer (PCa), suggesting that it could potentially contribute to progression of PCa. Estrogen receptor beta (ERβ) is a tumor suppressor gene in PCa. However, whether C/EBPβ could regulate ERβ by promoter methylation is still poorly understood.In this study, expression levels of C/EBPβ and ERβ in two PC lines (LNCap and PC-3), prostatic epithelial cell line (RWPE-1), forty-eight paired non-cancerous and cancerous peripheral blood samples were examined via qRT-PCR, western blotting and methylation-specific PCR. In addition, PCa cell line was infected with pCDH-C/EBPβ and pLKO.1-C/EBPβ and expression levels of C/EBPβ, ERβ and DNA methyltransferases were detected. Finally, the role of C/EBPβ in proliferation and apoptosis of PCa cell lines was examined by MTT and flow cytometer assay. Our results show a higher frequency of promoter methylation of ERβ levels in blood samples from PCa patients (16 of 48 cases) compared with that from healthy controls (3 of 48). Besides, elevated expression levels of C/EBPβ were found in PCa patients and two PCa lines (LNCap and PC-3) compared to non-cancerous cases or prostatic epithelial cell line (RWPE-1), while opposite expression levels of ERβ were found. Overexpression of C/EBPβ could regulate ERβ expression, DNA methyltransferases expression, cell proliferation and apoptosis. Our results support the conclusion that C/EBPβ down-regulated ERβ expression through increasing its promoter methylation, and then regulated proliferation and apoptosis in PCa.

摘要

CCAAT 增强子结合蛋白β（C/EBPβ）在前列腺癌（PCa）的癌变后期过度表达，表明其可能有助于 PCa 的进展。雌激素受体β（ERβ）是 PCa 的肿瘤抑制基因。然而，C/EBPβ 是否可以通过启动子甲基化来调节 ERβ 仍知之甚少。

在这项研究中，通过 qRT-PCR、western blot 和甲基化特异性 PCR 检测了两种 PC 系（LNCap 和 PC-3）、前列腺上皮细胞系（RWPE-1）以及 48 对非癌和癌外周血样本中 C/EBPβ 和 ERβ 的表达水平。此外，用 pCDH-C/EBPβ 和 pLKO.1-C/EBPβ 感染 PCa 细胞系，检测 C/EBPβ、ERβ 和 DNA 甲基转移酶的表达水平。最后，通过 MTT 和流式细胞仪检测 C/EBPβ 在 PCa 细胞系中的增殖和凋亡作用。

我们的结果显示，与健康对照组（48 例中的 3 例）相比，PCa 患者血液样本中 ERβ 水平的启动子甲基化频率更高（48 例中的 16 例）。此外，与非癌病例或前列腺上皮细胞系（RWPE-1）相比，在 PCa 患者和两种 PCa 系（LNCap 和 PC-3）中发现 C/EBPβ 的表达水平升高，而 ERβ 的表达水平则相反。C/EBPβ 的过表达可以调节 ERβ 的表达、DNA 甲基转移酶的表达、细胞增殖和凋亡。

我们的研究结果支持这样的结论，即 C/EBPβ 通过增加其启动子甲基化下调 ERβ 的表达，从而调节 PCa 的增殖和凋亡。