profiling of hypothalamus from mice s.c. injected with LL/2(LLC1) lung carcinoma cells vs. PBS

The main function of the nervous system is to maintain homeostasis by sensing and reacting to signals that reach a certain threshold 1-5. For example, the brain can sense immune peripheral events through soluble compounds or the vagus nerve and can react through activation of the hypothalamus-pituitary-adrenal axis, resulting in the modulation of an ongoing immune response. Cancer progression is characterized by high mutation rates, with each mutation potentially promoting alarm signals during the 10 to 15 years of cancer development before clinical detection. It is not known, however, whether the brain can recognize the presence of a peripheral tumour, and if this recognition can be molecularly assessed. Using genome-wide expression analysis in a model of lung carcinoma, we show that a tumor growing at the periphery can indeed promote changes in the expression levels of defined sets of genes in the hypothalamus. These changes occur as early as 18 h after tumour cell injection and involve specific signalling pathways. These findings prove that cancer-derived signals are effective in eliciting specific changes in gene expression in discrete brain regions and open a question regarding the potential role of brain genes in cancer outcomes Keywords: gene expression profile of the hypothalamus in response to peripheral tumor cells We used two-color oligonucleotides in-house printed microarrays in a case-control direct design with two technical replicates in a dye swap design. We analyzed 3 different time points: 18, 72 and 192 h after tumor cells or PBS injection. We performed 4 samples (biological replicates) for 18 h time point, 5 samples for 72 h time point, and 6 samples for 192 h time point.

神经系统的核心功能是通过感知并响应达到特定阈值的信号以维持内环境稳态1-5。例如，大脑可通过可溶性分子或迷走神经感知外周免疫事件，并通过激活下丘脑-垂体-肾上腺轴做出反应，从而调控正在进行中的免疫应答。
癌症进展以高突变率为典型特征，在临床确诊前的10至15年癌症发生阶段，每一次突变均可能触发警报信号。
然而目前尚不清楚大脑是否能够识别外周肿瘤的存在，以及该识别过程是否可通过分子手段进行评估。
本研究通过肺癌模型的全基因组表达分析证实，外周生长的肿瘤确实可诱导下丘脑内特定基因集的表达水平发生改变。这类变化最早可在肿瘤细胞注射后18小时出现，并涉及特定的信号通路。本研究结果证明，肿瘤来源的信号可有效引发特定脑区基因表达的特异性改变，同时提出了一个关于大脑基因在癌症转归中潜在作用的研究问题。
关键词：外周肿瘤细胞刺激下的下丘脑基因表达谱
本研究采用病例对照直接设计，使用自制的双色寡核苷酸打印微阵列，并通过染料互换实验设计设置2次技术重复。我们分析了肿瘤细胞或磷酸盐缓冲液（PBS）注射后18、72及192小时三个不同时间点的样本。其中18小时时间点设置4份生物学重复样本，72小时时间点设置5份生物学重复样本，192小时时间点设置6份生物学重复样本。