Nojiri Kazunori, Iwakawa Mayumi, Ichikawa Yasushi, Imadome Kaori, Sakai Minako, Nakawatari Miyako, Ishikawa Ken-Ichi, Ishikawa Atsuko, Togo Shinji, Tsujii Hirohiko, Shimada Hiroshi, Imai Takashi
Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, Chiba, Japan.
Exp Biol Med (Maywood). 2009 Jan;234(1):112-22. doi: 10.3181/0806-RM-189. Epub 2008 Nov 7.
While the pre-treatment status of cancer is generally correlated with outcome, little is known about microenvironmental change caused by anti-cancer treatment and how it may affect outcome. For example, treatment may lead to induction of gene expression that promotes resistance to therapy. In the present study, we attempted to find a gene that was both induced by irradiation and associated with radioresistance in tumors. Using single-color oligo-microarrays, we analyzed the gene expression profiles of two murine squamous cell carcinomas, NR-S1, which is highly radioresistant, and SCCVII, which is radiosensitive, after irradiation with 137-Cs gamma rays or carbon ions. Candidate genes were those differentially regulated between NR-S1 and SCCVII after any kind of irradiation. Four genes, Efna1 (Ephrin-A1), Sprr1a (small proline-rich protein 1A), Srgap3 (SLIT-ROBO Rho GTPase activating protein 3) and Xrra1 [RIKEN 2 days neonate thymus thymic cells (NOD) cDNA clone E430023D08 3'], were selected as candidate genes associated with radiotherapy-induced radioresistance. We focused on Efna1, which encodes a ligand for the Eph receptor tyrosine kinase known to be involved in the vascular endothelial growth factor (VEGF) pathway. We used immunohistochemical methods to detect expression of Ephrin-A1, VEGF, and the microvascular marker CD31 in radioresistant NR-S1 tumor cells. Ephrin-A1 was detected in the cytoplasm of NR-S1 tumor cells after irradiation, but not in SCCVII tumor cells. Irradiation of NR-S1 tumor cells also led to significant increases in microvascular density, and up-regulation of VEGF expression. Our results suggest that radiotherapy-induced changes in gene expression related with angiogenesis might also modulate microenvironment and influence responsiveness of tumors.
虽然癌症的预处理状态通常与预后相关，但对于抗癌治疗引起的微环境变化及其如何影响预后却知之甚少。例如，治疗可能导致促进治疗抗性的基因表达的诱导。在本研究中，我们试图找到一个既受辐射诱导又与肿瘤中的放射抗性相关的基因。使用单色寡核苷酸微阵列，我们分析了两种小鼠鳞状细胞癌NR-S1（高度放射抗性）和SCCVII（放射敏感）在接受137-Csγ射线或碳离子照射后的基因表达谱。候选基因是在任何一种照射后NR-S1和SCCVII之间差异调节的基因。四个基因，Efna1（Ephrin-A1）、Sprr1a（富含脯氨酸的小蛋白1A）、Srgap3（SLIT-ROBO Rho GTP酶激活蛋白3）和Xrra1 [理化学研究所2天龄新生胸腺胸腺细胞（NOD）cDNA克隆E430023D08 3']，被选为与放疗诱导的放射抗性相关的候选基因。我们重点研究了Efna1，它编码一种已知参与血管内皮生长因子（VEGF）途径的Eph受体酪氨酸激酶的配体。我们使用免疫组织化学方法检测放射抗性NR-S1肿瘤细胞中Ephrin-A1、VEGF和微血管标志物CD31的表达。照射后在NR-S1肿瘤细胞的细胞质中检测到Ephrin-A1，但在SCCVII肿瘤细胞中未检测到。照射NR-S1肿瘤细胞也导致微血管密度显著增加，以及VEGF表达上调。我们的结果表明，放疗诱导的与血管生成相关的基因表达变化也可能调节微环境并影响肿瘤的反应性。
