Gene expression in the colon tumor of AOM/DSS-treated RBJ-/- mice

The purpose of this study was to determine which genes are differentially regulated by the Ras-related small GTPase RBJ after induction by AOM/DSS treatment in the colon of C57BL/6 mice compared to RBJ+/+ mice. The results demonstrate decreased induction of cell proliferation-associated genes in RBJ-/- mice than in RBJ+/+ mice on day 80 after AOM/DSS treatment. The majority of differentially expressed genes are regulated by MEK/ERK signaling pathway. Thus RBJ may be involved in the regulation of tumor progression and tumorigenesis. RBJ+/+ and RBJ-/- mice (5/group) were either untreated or treated with AOM (12 mg/kg) on day 0. On day 7, 3 cycles of DSS (2.5% in drinking water; 7 days/cycle) were itiated, each separated by 14 days of vehicle control (water). Mice were sacrificed on day 80 day after AOM treatments.Tumor tissues in distal colon of the mice were prepared for total RNA individually. Equal amounts of RNA derived from 3 individual mice per group were mixed together, and assayed for gene expression using Affymetrix mouse 430 2.0 arrays.

本研究旨在明确，相较于RBJ野生型（RBJ+/+）小鼠，在C57BL/6小鼠结肠经氧化偶氮甲烷（AOM）/葡聚糖硫酸钠（DSS）联合诱导处理后，哪些基因可被Ras相关小GTP酶（Ras-related small GTPase）RBJ差异调控。
研究结果显示，AOM/DSS处理后第80天，RBJ敲除（RBJ-/-）小鼠的细胞增殖相关基因诱导表达水平显著低于RBJ+/+小鼠。多数差异表达基因受MEK/ERK信号通路调控，因此RBJ可能参与肿瘤进展与肿瘤发生的调控过程。
实验设置每组5只RBJ+/+与RBJ-/-小鼠，分为未处理组与AOM处理组（于第0天按12mg/kg剂量给予AOM处理）。第7天启动3轮DSS处理：在饮用水中添加2.5%浓度的DSS，每轮处理持续7天，每轮间隔14天的溶剂对照（单纯饮用水）处理。小鼠于AOM处理后第80天处死，分别采集其远端结肠肿瘤组织以提取总RNA。每组取3只个体小鼠的等量RNA进行混合，随后采用Affymetrix小鼠基因芯片430 2.0阵列进行基因表达检测。