Screening of biomarkers for liver adenoma in low-dose-rate gamma-ray-irradiated mice.

Purpose: Chronic low-dose-rate (20 mGy/d) gamma-irradiation increases the incidence of hepatocellular adenomas (HCA) in female B6C3F1 mice. The purpose of this study is to identify potential serum biomarkers for these HCAs by a new approach. Material and methods: Microarray analysis were performed to compare the gene expression profiles of HCAs from mice exposed to low-dose-rate gamma rays with those of normal livers from non-irradiated mice. From the differentially expressed genes, those for possibly secretory proteins were selected. Then the levels of the proteins in sera were analysed by ELISA. Results: Microarray analysis identified 4,181 genes differentially expressed in HCAs (>2.0-fold). From these genes, those for Alpha-fetoprotein (Afp), Alpha-1B- glycoprotein (A1bg) and Serine peptidase inhibitor Kazal type 3 (Spink3) were selected as the genes for candidate proteins. ELISA revealed that the levels of Afp and A1bg proteins in sera significantly increased and decreased, respectively, in low dose-rate irradiated mice with HCAs and also same tendency was observed in human patients with hepatocellular carcinomas. Conclusion: These results indicate that A1bg could be a new serum biomarker for liver tumor. This new approach of using microarray to select genes for secretory proteins is useful for prediction of novel tumor markers in sera.

研究目的：慢性低剂量率（20 mGy/d）γ射线照射可增加雌性B6C3F1小鼠肝细胞腺瘤（Hepatocellular Adenomas, HCA）的发病率。本研究旨在通过全新方法，筛选针对此类肝细胞腺瘤的潜在血清生物标志物。
材料与方法：采用基因芯片分析，对比经低剂量率γ射线照射小鼠的肝细胞腺瘤组织与未照射小鼠正常肝脏组织的基因表达谱。从差异表达基因中筛选出可能编码分泌蛋白的基因，随后通过酶联免疫吸附测定（Enzyme-Linked Immunosorbent Assay, ELISA）分析血清中对应蛋白的水平。
结果：基因芯片分析共筛选出4181个在肝细胞腺瘤中表达量差异≥2.0倍的差异表达基因。从中选取甲胎蛋白（Alpha-fetoprotein, Afp）、α1B-糖蛋白（Alpha-1B-glycoprotein, A1bg）以及丝氨酸蛋白酶抑制剂Kazal型3（Serine peptidase inhibitor Kazal type 3, Spink3）的编码基因作为候选蛋白相关基因。酶联免疫吸附测定结果显示，在携带肝细胞腺瘤的低剂量率照射小鼠血清中，甲胎蛋白水平显著升高，而α1B-糖蛋白水平显著降低；该表达趋势在肝细胞癌患者的血清样本中同样存在。
结论：本研究结果表明，α1B-糖蛋白可作为肝脏肿瘤的新型血清生物标志物。这种通过基因芯片筛选分泌蛋白编码基因的全新方法，可有效用于血清中新型肿瘤标志物的预测与开发。