Molecular analysis of 4NQO-induced rat tongue cancers using cDNA microarrays - for a purpose of clinical application

在这里，我们报告了利用cDNA微阵列来测量4-硝基喹啉1-氧化物（4NQO）诱导的大鼠舌癌组织中基因表达的全局模式。基因表达的测量是两种大鼠的分子分化的基础，高易感的Dark-Agouti （DA）大鼠和低易感的Wistar/Furth （WF）大鼠（Kitano et al，日本癌症杂志83,845 - 50,1992;Kitano et al，日本癌症杂志87,1097 - 101,1996）。为了定量表达基因，我们将两株大鼠舌癌（cy5标记）和4-硝基喹啉1-氧化物诱导的大鼠舌癌（cy5标记）的cDNA平行杂交的微阵列荧光进行叠加分析。根据Cy5/Cy3信号强度的比值，从四重杂交中评估的表达因子作为平均值确定。在本实验中，3倍以上的基因表达率的增加或减少被认为是相关的。4nqo诱导的DA大鼠舌癌（直径15mm）中上调和下调的基因分别为337个和220个，WF大鼠4nqo诱导的舌癌（直径5mm）中上调和下调的基因分别为182个和81个。对于先前被描述为大鼠舌癌易感性qtl候选基因（Tanuma et al ., Cancer Res 58, 1660- 4,1998; Tanuma et al ., Jpn J Cancer Res 92, 610- 6,2001; Tanuma et al ., Int J Cancer 102, 638- 42,2002），微阵列分析表明，舌癌在DA大鼠和WF大鼠之间表现出明显的基因表达比率差异，例如NQO1基因。这些结果表明，DA大鼠和WF大鼠在其组织学类型相同的舌癌中可能表现出明显的差异基因表达特征，即鳞状细胞癌。

Here we report that use of cDNA microarrays to measure global patterns of gene expression in 4-nitroquinoline 1-oxide (4NQO)-induced rat tongue carcinoma tissue. Measurements of gene expression have been the basis for molecular differentiation of two strains of the rats, highly susceptible Dark-Agouti (DA) rat and poorly susceptible Wistar/Furth (WF) rat (Kitano et al, Jpn J Cancer Res 83, 845-50, 1992 ; Kitano et al, Jpn J Cancer Res 87, 1097-101, 1996). For quantification of the gene expression, fluorescence derived from microarrays hybridized in parallel to control (Cy3-labelled) and 4-nitroquinoline 1-oxide-induced rat tongue cancer (Cy5-labelled) cDNA samples of the two strains of rats were overlayed and analyzed. The expression factor --- evaluated from quadruplicate hybridization --- was determined as a mean value according to the ratios of the Cy5/Cy3 signal intensities. More than 3-fold increases or decreases of the gene expression ratios were regarded as relevant in this experiment. The genes which were up-regulated and down-regulated in a 4NQO-induced tongue cancer (15mm in the diameter) of a DA rat was 337 and 220, respectively, and another 4NQO-induced tongue cancer (5mm in the diameter) developed in a WF rat was 182 and 81, respectively. Regarding the genes previously described as the candidates for QTLs involved in susceptibility of tongue carcinogenesis in the rat (Tanuma et al, Cancer Res 58, 1660-4, 1998 ; Tanuma et al, Jpn J Cancer Res 92, 610-6, 2001 ; Tanuma et al, Int J Cancer 102, 638-42, 2002), microarray analysis demonstrated that the tongue cancers showed a distinct difference in gene expression ratios, for example of NQO1 gene, between the DA rat and WF rat.These results indicate that the DA rat and WF rat possibly show a distinct signature of differential gene expression in their tongue cancers of which histologic types are the same, I.e., squamous cell carcinoma.