Kruppel-like factor 4 is transactivated by butyrate in colon cancer cells
Kruppel-like factor 4 is transactivated by butyrate in colon cancer cells
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DOI：
10.1093/jn/134.4.792
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发表时间：
2004-04-01
影响因子：
4.2
通讯作者：
Tseng, CC
中科院分区：
文献类型：
--
作者：
Chen, ZY;Rex, S;Tseng, CC
高纤维饮食可降低结直肠癌的发病率，而源自膳食纤维的 SCFA 参与结肠上皮细胞生长、分化和凋亡的调节。这些影响的中介因素仍然不明确。 Kruppel 样因子 4 (KLF4/GKLF) 是一种锌指转录因子，表现出一些与结肠中 SCFA 相似的生理特性。本研究旨在检验 KLF4 在结肠癌 HT-29 细胞中丁酸盐介导的作用中的作用。在 HT-29 细胞中，丁酸盐以剂量和时间依赖性方式诱导 KLF4 mRNA 表达并刺激 KLF4 启动子活性。在具有不同碳长度（C3-C7）的 SCFA 中观察到类似的效果，但在支链异丁酸中没有观察到类似的效果，表明 SCFA 的刺激特性与脂肪酸结构有关。使用 KLF4 启动子的 5' 缺失和突变构建体进行的转染研究表明，丁酸响应元件位于假定的刺激蛋白 (Sp)1 结合位点。使用含有共有 Sp1 结合元件的寡核苷酸进行电泳迁移率变动分析，揭示了一种 DNA-蛋白质复合物，该复合物通过丁酸盐处理得到增强，并通过 Sp1 抗血清进行超迁移。此外，丁酸盐对细胞生长和 KLF4 mRNA 表达的影响与组蛋白脱乙酰酶 (HDAC-1) 特异性抑制剂曲古抑菌素 A (TSA) 相同。 HDAC1 的过表达显着减弱丁酸盐或 TSA 对 KLF4 启动子的转录激活。这些结果表明 KLF4 可能作为丁酸盐的下游效应器之一，介导其在结肠中的生长抑制作用。此外，丁酸对 KLF4 的反式激活似乎是通过与启动子上的 Sp1 结合域相互作用介导的，并且也可能涉及组蛋白乙酰化。
High-fiber diets decrease the incidence of colorectal cancers, and SCFA, derived from dietary fiber, are involved in the regulation of cell growth, differentiation, and apoptosis of the colonic epithelium. The mediators of these effects remain poorly defined. Kruppel-like factor-4 (KLF4/GKLF) is a zinc-finger transcription factor that exhibits some physiologic properties similar to those of SCFA in the colon. The present study was undertaken to examine the role of KLF4 in the butyrate-mediated effect in colon cancer HT-29 cells. Butyrate induced KLF4 mRNA expression and stimulated KLF4 promoter activity in a dose- and time-dependent manner in HT-29 cells. Similar effects were observed in SCFA possessing different carbon lengths (C3-C7), but not in branched isobutyric acid, indicating that the stimulatory properties of SCFA were related to fatty acid structure. Transfection studies using 5' deletion and mutant constructs of the KLF4 promoter demonstrated that the butyrate-responsive element was located at a putative stimulatory protein (Sp)1-binding site. Electrophoretic mobility shift assays using an oligonucleotide containing a consensus Sp1-binding element revealed a DNA-protein complex that was enhanced by butyrate treatment and supershifted by the Sp1 antiserum. Furthermore, the effects of butyrate on cell growth and KLF4 mRNA expression were the same as those of trichostatin A (TSA), a specific inhibitor of histone deacetylase (HDAC-1). Overexpression of HDAC1 significantly attenuated transcriptional activation of the KLF4 promoter by butyrate or TSA. These results suggest that KLF4 may function as one of the downstream effectors of butyrate that mediates its growth arrest effect in the colon. Moreover, transactivation of KLF4 by butyrate appears to be mediated through interaction with a Sp1-binding domain on the promoter and is also likely to involve histone acetylation.