1,2-二甲基肼（DMH）诱导大鼠结肠肿瘤的基因表达谱和基因组改变。
Gene expression profile and genomic alterations in colonic tumours induced by 1,2-dimethylhydrazine (DMH) in rats.
机构信息
Department of Pharmacology, University of Florence, 6 Viale Pieraccini, 50139 Florence, Italy.
出版信息
BMC Cancer. 2010 May 11;10:194. doi: 10.1186/1471-2407-10-194.
BACKGROUND
Azoxymethane (AOM) or 1,2-dimethylhydrazine (DMH)-induced colon carcinogenesis in rats shares many phenotypical similarities with human sporadic colon cancer and is a reliable model for identifying chemopreventive agents. Genetic mutations relevant to human colon cancer have been described in this model, but comprehensive gene expression and genomic analysis have not been reported so far. Therefore, we applied genome-wide technologies to study variations in gene expression and genomic alterations in DMH-induced colon cancer in F344 rats.
METHODS
For gene expression analysis, 9 tumours (TUM) and their paired normal mucosa (NM) were hybridized on 4 x 44K Whole rat arrays (Agilent) and selected genes were validated by semi-quantitative RT-PCR. Functional analysis on microarray data was performed by GenMAPP/MappFinder analysis. Array-comparative genomic hybridization (a-CGH) was performed on 10 paired TUM-NM samples hybridized on Rat genome arrays 2 x 105K (Agilent) and the results were analyzed by CGH Analytics (Agilent).
RESULTS
Microarray gene expression analysis showed that Defcr4, Igfbp5, Mmp7, Nos2, S100A8 and S100A9 were among the most up-regulated genes in tumours (Fold Change (FC) compared with NM: 183, 48, 39, 38, 36 and 32, respectively), while Slc26a3, Mptx, Retlna and Muc2 were strongly down-regulated (FC: -500; -376, -167, -79, respectively). Functional analysis showed that pathways controlling cell cycle, protein synthesis, matrix metalloproteinases, TNFalpha/NFkB, and inflammatory responses were up-regulated in tumours, while Krebs cycle, the electron transport chain, and fatty acid beta oxidation were down-regulated. a-CGH analysis showed that four TUM out of ten had one or two chromosomal aberrations. Importantly, one sample showed a deletion on chromosome 18 including Apc.
CONCLUSION
The results showed complex gene expression alterations in adenocarcinomas encompassing many altered pathways. While a-CGH analysis showed a low degree of genomic imbalance, it is interesting to note that one of the alterations concerned Apc, a key gene in colorectal carcinogenesis. The fact that many of the molecular alterations described in this study are documented in human colon tumours confirms the relevance of DMH-induced cancers as a powerful tool for the study of colon carcinogenesis and chemoprevention.
背景
氧化偶氮甲烷（AOM）或 1,2-二甲基肼（DMH）诱导的大鼠结肠癌与人类散发性结肠癌具有许多表型相似性，是鉴定化学预防剂的可靠模型。在该模型中已描述了与人类结肠癌相关的遗传突变，但迄今为止尚未报道全面的基因表达和基因组分析。因此，我们应用全基因组技术研究 DMH 诱导的 F344 大鼠结肠癌中基因表达和基因组改变的差异。
方法
用于基因表达分析，9 个肿瘤（TUM）及其配对的正常粘膜（NM）在 4 x 44K 全大鼠阵列（Agilent）上杂交，并通过半定量 RT-PCR 验证所选基因。通过 GenMAPP/MappFinder 分析对微阵列数据进行功能分析。对 10 对 TUM-NM 样本进行阵列比较基因组杂交（a-CGH），在 Rat 基因组阵列 2 x 105K（Agilent）上杂交，并通过 CGH Analytics（Agilent）分析结果。
结果
微阵列基因表达分析表明，Defcr4、Igfbp5、Mmp7、Nos2、S100A8 和 S100A9 是肿瘤中上调最明显的基因之一（与 NM 相比的倍数变化（FC）：183、48、39、38、36 和 32），而 Slc26a3、Mptx、Retlna 和 Muc2 则强烈下调（FC：-500；-376、-167、-79）。功能分析表明，控制细胞周期、蛋白质合成、基质金属蛋白酶、TNFalpha/NFkB 和炎症反应的途径在肿瘤中上调，而克雷布斯循环、电子传递链和脂肪酸β氧化则下调。a-CGH 分析表明，在 10 个 TUM 中有四个出现一个或两个染色体异常。重要的是，一个样本在包括 Apc 在内的 18 号染色体上出现缺失。
结论
结果表明，腺癌细胞中存在复杂的基因表达改变，涉及许多改变的途径。虽然 a-CGH 分析显示基因组失衡程度较低，但值得注意的是，其中一个改变涉及 Apc，这是结直肠癌发生的关键基因。本研究中描述的许多分子改变在人类结肠癌中已有记载，这证实了 DMH 诱导的癌症作为研究结肠癌发生和化学预防的有力工具的相关性。
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