Department of Pharmaceutical Sciences, College of Pharmacy, North Dakota State University, Fargo, North Dakota 58108, USA.
Gastroenterology. 2013 Aug;145(2):437-46. doi: 10.1053/j.gastro.2013.04.012. Epub 2013 Apr 22.
BACKGROUND & AIMS: Vitamin D protects against colorectal cancer through unclear mechanisms. We investigated the effects of calcitriol (1α,25-dihydroxyvitamin D3; the active form of vitamin D) on levels of different microRNAs (miRNAs) in colorectal cancer cells from humans and xenograft tumors in mice.
Expression of miRNAs in colorectal cancer cell lines was examined using the Ambion mirVana miRNA Bioarray. The effects of calcitriol on expression of miR-627 and cell proliferation were determined by real-time polymerase chain reaction and WST-1 assay, respectively; growth of colorectal xenograft tumors was examined in nude mice. Real-time polymerase chain reaction was used to analyze levels of miR-627 in human colon adenocarcinoma samples and nontumor colon mucosa tissues (controls).
In HT-29 cells, miR-627 was the only miRNA significantly up-regulated by calcitriol. Jumonji domain containing 1A (JMJD1A), which encodes a histone demethylase, was found to be a target of miR-627. By down-regulating JMJD1A, miR-627 increased methylation of histone H3K9 and suppressed expression of proliferative factors, such as growth and differentiation factor 15. Calcitriol induced expression of miR-627, which down-regulated JMJD1A and suppressed growth of xenograft tumors from HCT-116 cells in nude mice. Overexpression of miR-627 prevented proliferation of colorectal cancer cell lines in culture and growth of xenograft tumors in mice. Conversely, blocking the activity of miR-627 inhibited the tumor suppressive effects of calcitriol in cultured colorectal cancer cells and in mice. Levels of miR-627 were decreased in human colon adenocarcinoma samples compared with controls.
miR-627 mediates tumor-suppressive epigenetic activities of vitamin D on colorectal cancer cells and xenograft tumors in mice. The messenger RNA that encodes the histone demethylase JMJD1A is a direct target of miR-627. Reagents designed to target JMJD1A or its messenger RNA, or increase the function of miR-627, might have the same antitumor activities of vitamin D without the hypercalcemic side effects.
维生素 D 通过尚不清楚的机制来预防结直肠癌。我们研究了 1α,25-二羟维生素 D3（维生素 D 的活性形式）对人类结直肠癌细胞系和小鼠异种移植肿瘤中不同 microRNAs（miRNAs）水平的影响。
使用 Ambion mirVana miRNA 生物芯片检测结直肠癌细胞系中 miRNAs 的表达。通过实时聚合酶链反应和 WST-1 测定分别确定 calcitriol 对 miR-627 表达和细胞增殖的影响；在裸鼠中检查结直肠异种移植肿瘤的生长。使用实时聚合酶链反应分析人结肠腺癌样本和非肿瘤结肠黏膜组织（对照）中 miR-627 的水平。
在 HT-29 细胞中，miR-627 是唯一被 calcitriol 显著上调的 miRNA。发现含有 Jumonji 结构域的 1A（JMJD1A）是 miR-627 的靶基因，它编码一种组蛋白去甲基酶。通过下调 JMJD1A，miR-627 增加了组蛋白 H3K9 的甲基化，并抑制了增殖因子的表达，如生长分化因子 15。Calcitriol 诱导 miR-627 的表达，进而下调 JMJD1A，抑制裸鼠中 HCT-116 细胞异种移植肿瘤的生长。miR-627 的过表达可阻止培养中的结直肠癌细胞系的增殖和裸鼠异种移植肿瘤的生长。相反，阻断 miR-627 的活性可抑制 calcitriol 在培养的结直肠癌细胞和小鼠中的肿瘤抑制作用。与对照相比，人结肠腺癌样本中的 miR-627 水平降低。
miR-627 介导维生素 D 对结直肠癌细胞和小鼠异种移植肿瘤的肿瘤抑制性表观遗传活性。编码组蛋白去甲基酶 JMJD1A 的信使 RNA 是 miR-627 的直接靶标。设计靶向 JMJD1A 或其信使 RNA 或增加 miR-627 功能的试剂可能具有与维生素 D 相同的抗肿瘤活性，而没有高钙血症的副作用。
