Molecular analysis of flg and its products for targeted therapy on brain tumors

碱性成纤维细胞生长因子（bFGF）在胶质瘤细胞的生长中起重要作用。本研究分析bFGF受体的编码基因fms样基因（fms-like gene, flg），不仅阐明其在胶质瘤细胞生长过程中的生物学活性，而且探讨其作为恶性胶质瘤治疗分子靶点的潜力。首先，我们使用RT-PCR技术分析了手术获得的脑肿瘤组织中flg mRNA的表达。我们对65个样本进行了研究，发现flg mRNA在胶质瘤组织中的表达比正常脑组织增强。在恶性转化或复发的病例中，其表达进一步增强。组织病理学上，flg表达增强与胶质瘤组织的高细胞性相关。基于这些事实，我们用Southern和Northern印迹技术对培养的胶质母细胞瘤细胞系进行了更详细的分子分析。在Southern分析中未观察到flg基因扩增，而Northern分析中flg基因表达增加，说明其表达可能受上游未知转录因子控制。此外，免疫组织化学分析表明，与正常成纤维细胞相比，胶质母细胞瘤细胞系中检测到的flg产物更多。反义寡核苷酸在浓度为20mum时能有效抑制胶质母细胞瘤细胞的生长。这些结果表明，FGF-flg系统的自分泌或旁分泌环在胶质瘤细胞增殖中起重要作用，这也表明flg可以作为治疗胶质瘤的良好候选分子靶点。

It has been reported that basic fibroblast growth factor (bFGF) plays an important role in the growth of glioma cells. The gene encoding receptor of bFGF,namely fms-like gene (flg), was analyzed in this study not only to clarify its biological activity in the growth of glioma cells but also to examine its potential to be a molecular target in treatment of malignant gliomas. First we analyzed expression of flg mRNA in brain tumor tissues obtained at surgery using RT-PCR technique. Sixty-five samples were studied, and it was indicated that expression of flg mRNA in glioma tissues were more enhanced than normal brain tissues. Moreover, it's expression was further enhanced in cases with malignant transformation or recurrence. Histopathologically, enchanced flg expression was in correlation with high cellularity in glioma tissues. Based on these facts, we made more detailed molecular analyzes by Southern and Northern blot techniques on cultured glioblastoma cell lines. flg gene amplification was not observed in Southern analysis, while its expression was increased in Northern, indicating its expression should be controlled by upstream unknown transcription factors. In addition, immunohistochemical analyzes indicated that the flg-product was detected more in glioblastoma cell lines than normal fibroblasts. Anti-sense oligo nucleotide effectively suppressed the growth of glioblastoma cells at concentration of 20 muM.All these results indicate that autocrine or paracrine loops of FGF-flg system is essential in glioma cell proliferation, which also indicates that flg can be a good candidate as a molecular target in treatment of gliomas.