Tenascin-C : 骨肉瘤预后标志物

背景：在过去的数十年间,转移性骨肉瘤的治疗一直是亟待解决的临床难题。细胞外基质蛋白作为肿瘤微环境关键组成成份，在骨肉瘤进展过程中发挥着重要作用。在此，我们通过基因芯片技术分析不同转移能力骨肉瘤细胞系基因表达，在编码细胞外基质蛋白基因中寻找与骨肉瘤进展相关的基因，并通过免疫组化技术检测这些基因在骨肉瘤标本中的表达，以评价其与临床预后的关系。方法：通过基因芯片技术分析骨肉瘤细胞系MG63-wt及其高转移亚系MG63-A1的基因表达差异。对两个细胞系间表达差异达4倍以上的基因通过Gene Ontology方法筛选编码细胞外基质蛋白的基因。通过RT-PCR和western blot验证候选基因的表达水平，免疫组化检测候选基因在骨肉标本中的表达以分析其与临床预后的关系。结果：基因芯片检测和Gene Ontology分析发现一个重要的细胞外基质蛋白――Tenascin-C的表达在高转移骨肉瘤细胞系MG63-A1中明显降低。RT-PCR和western blot分别在mRNA水平和蛋白质水平证实其表达水平。免疫组化检测发现Tenascin-C在骨肉瘤标本中的阳性表达见于细胞外间隙。Tenascin-C低表达组（＜20％）患者的预后较差，差异有统计学意义。结论：Tenascin-C的表达水平与骨肉瘤患者预后呈正相关。Tenascin-C在骨肉瘤进展中的生物学作用有待进一步的体外细胞模型研究和更大样本临床研究。

Tenasicn c as a prognostic biomarker in osteosarcoma

BACKGROUND. Metastatic osteosarcoma remained a challenge over the past decades. Extracelluar Matrix (ECM) Proteins play an important role in the progression of osteosarcoma, as a pivotal component of tumor microenvironment. Here, we present our data to identify potential genes belonging to ECM characterize the progression of osteosarcoma with gene array analysis of osteosarcoma cell lines with different metastasis potential and to investigate the role of the candidate genes in osteosarcoma tissue samples by immunohistochemistry analysis.METHODS. Osteosarcoma cell lines MG63 wild type and its derivatives MG63-A1 with high metastatic potential underwent oligonucleotide microarray analyses. Gene ontology analysis was used for screening the deregulated genes between 2 cell lines which upregulate or downregulate more than 4 folds, particularly focusing on mRNAs encoding Extracellualr Matrix proteins. The expression of the candidate genes were then validated by RT-PCR for mRNA expression as well as Western Blotting for protein expression. Immunhistochemistry was performed on 37 osteosarcoma specimens for probe the potential role of the candidate genes in clinical context.RESULTS. Microarray data and Gene Ontology analysis showed that Tenascin-C, a critical component of ECM, is significantly down-regulated in the highly metastatic cell lines MG63-A1 compared to the parental osteosarcoma cell line MG63-wt. This finding was validated on both mRNA and protein levels. Immunohistochemistry analysis found that positive Tenasici-C was observed as diffuse staining in the intercellular space in osteosarcoma specimen. Low grade Tenascin-C expression (less than 20%) in osteosarcoma specimens associated with poor survival.CONCLUSIONS. Tenascin-C expression level coorelates with the survival of osteosarcoma patients. Its biological function role in the progression of osteosarcoma needs further investigation in in-vitro assays using osteosarcoma cell line models and large scale clinical study.