胃癌中 TGF-β1 基因启动子的高甲基化。
Hypermethylation of TGF-β1 gene promoter in gastric cancer.
机构信息
Yong-Qi Wang, Yu-Min Li, School of Life Sciences, Lanzhou University, Lanzhou 730000, Gansu Province, China.
出版信息
World J Gastroenterol. 2013 Sep 7;19(33):5557-64. doi: 10.3748/wjg.v19.i33.5557.
AIM
To examine transforming growth factor-β1 (TGF-β1) promoter methylation in gastric cancer and to determine if Helicobacter pylori (H. pylori) or interleukin (IL)-1β could induce TGF-β1 hypermethylation in vitro.
METHODS
We examined the frequency and extent of TGF-β1 promoter methylation using methylation-specific PCR in the gastric tissues from 47 gastric cancer patients and 39 non-gastric cancer subjects. H. pylori infection was confirmed by a positive result from either a serological test, histological analysis or C¹³ urea breath test. GES-1 and MKN-45 cells co-cultured with H. pylori or treated with IL-1β for 12, 24 and 48 h in vitro tested the effects of H. pylori or IL-1β on TGF-β1.
RESULTS
Twenty-four/forty-seven (51%) cases of gastric cancer (GC) tissues showed TGF-β1 promoter methylation, 15/47 (31.9%) cases of matched non-cancerous gastric mucosa tissues from the GC patients, and 11/39 (28%) case of the normal gastric mucosa tissues from non-GC subjects showed TGF-β1 promoter methylation (51% vs 28%, P < 0.05). Significantly higher levels of methylation of TGF-β1 were found in the tumor tissues than in non-tumor tissues from GC patients (0.24 ± 0.06 vs 0.17 ± 0.04, P < 0.05) and normal gastric tissues from non-GC subjects (0.24 ± 0.06 vs 0.15 ± 0.03, P < 0.05). TGF-β1 methylation was found in 48.3% of H. pylori-positive gastric mucosal tissues whereas only 23.1% of H. pylori-negative gastric mucosal tissues showed TGF-β1 methylation (48.3% vs 23.1%, P < 0.05). IL-1β appeared to induce a dose-dependent methylation of TGF-β1 and the strongest methylation was observed in GES-1 cells treated with 2.5 ng/mL of IL-1β for 48 h. Further studies showed that pre-treatment of GES-1 cells with 20 ng/mL IL-1RA for 1 h could partially abolish the effect of IL-1β on TGF-β1 methylation. Infection of GES-1 cells by H. pylori was not found to induce significant TGF-β1 promoter methylation.
CONCLUSION
Our data revealed that TGF-β1 promoter is methylated in GC patients. IL-1β may be an important mediator for H. pylori induced gene methylation during GC development.
目的
研究转化生长因子-β1（TGF-β1）启动子甲基化在胃癌中的作用，并确定幽门螺杆菌（H. pylori）或白细胞介素（IL）-1β是否能诱导体外 TGF-β1 过度甲基化。
方法
我们使用甲基化特异性 PCR 检测了 47 例胃癌患者和 39 例非胃癌患者胃组织中 TGF-β1 启动子甲基化的频率和程度。H. pylori 感染通过血清学检测、组织学分析或 C¹³尿素呼气试验阳性结果来确认。体外共培养 H. pylori 或用 IL-1β处理 GES-1 和 MKN-45 细胞 12、24 和 48 h，检测 H. pylori 或 IL-1β 对 TGF-β1 的影响。
结果
24/47（51%）例胃癌（GC）组织显示 TGF-β1 启动子甲基化，15/47（31.9%）例 GC 患者配对的非癌性胃黏膜组织，11/39（28%）例非 GC 患者的正常胃黏膜组织显示 TGF-β1 启动子甲基化（51%比 28%，P<0.05）。GC 患者肿瘤组织中 TGF-β1 的甲基化水平明显高于非肿瘤组织（0.24±0.06 比 0.17±0.04，P<0.05）和非 GC 患者的正常胃组织（0.24±0.06 比 0.15±0.03，P<0.05）。H. pylori 阳性胃黏膜组织中 TGF-β1 甲基化率为 48.3%，而 H. pylori 阴性胃黏膜组织中 TGF-β1 甲基化率为 23.1%（48.3%比 23.1%，P<0.05）。IL-1β 似乎诱导 TGF-β1 的剂量依赖性甲基化，在 GES-1 细胞中用 2.5 ng/ml 的 IL-1β 处理 48 h 时观察到最强的甲基化。进一步的研究表明，GES-1 细胞用 20 ng/ml 的 IL-1RA 预处理 1 h 可部分消除 IL-1β 对 TGF-β1 甲基化的作用。未发现 H. pylori 感染诱导 GES-1 细胞中 TGF-β1 启动子显著甲基化。
结论
我们的数据显示，GC 患者的 TGF-β1 启动子发生甲基化。IL-1β 可能是 H. pylori 诱导胃癌发生过程中基因甲基化的重要介质。
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