Raza Shaan M, Fuller Gregory N, Rhee Chang Hun, Huang Suyun, Hess Kenneth, Zhang Wei, Sawaya Raymond
Departments of Neurosurgery, Brain Tumor Center, The University of Texas M. D. Anderson Cancer Center, Houston, Texas, USA.
Clin Cancer Res. 2004 Jan 1;10(1 Pt 1):212-21. doi: 10.1158/1078-0432.ccr-0155-3.
In the field of cancer research, there has been a paucity of interest in necrosis, whereas studies focusing on apoptosis abound. In neuro-oncology, this is particularly surprising because of the importance of necrosis as a hallmark of glioblastoma (GBM), the most malignant and most common primary brain tumor, and the fact that the degree of necrosis has been shown to be inversely related to patient survival. It is therefore of considerable interest and importance to identify genes and gene products related to necrosis formation.
We used a nylon cDNA microarray to analyze mRNA expression of 588 universal cellular genes in 15 surgically resected human GBM samples with varying degrees of necrosis. Gene expression was correlated with the degree of necrosis using rank correlation coefficients. The expression of identified genes was compared with their expression in tissue samples from 5 anaplastic astrocytomas (AAs). Immunostaining was used to determine whether genes showing the most positive correlation with necrosis were increasingly expressed in tumor tissues, as grade of necrosis increased.
The hybridization results indicated that 26 genes showed significant correlation with the amount of necrosis. All 26 genes had functions associated with either Ras, Akt, tumor necrosis factor alpha, nuclear factor kappaB, apoptosis, procoagulation, or hypoxia. Nine genes were positively correlated with necrosis grade, and 17 genes were negatively correlated with necrosis grade. There were significant differences in the median expression levels of 3 of the 26 genes between grade III necrosis GBM and anaplastic astrocytoma (AA) samples; all but 1 of the genes had elevated expression when comparing necrosis grade III with AA samples. Two factors, the ephrin type A receptor 1 and the prostaglandin E(2) receptor EP4 subtype, not previously considered in this context, were highlighted because of their particularly high (positive) correlation coefficients; immunostaining showed the products of these two genes to be localized in perinecrotic and necrotic regions and to be overexpressed in grade III GBMs, but not AAs. These two molecules also showed significant correlation with survival of GBM patients (P = 0.0034) in a combined model.
The application of cDNA expression microarray analysis has identified specific genes and patterns of gene expression that may help elucidate the molecular basis of necrogenesis in GBM. Additional studies will be required to further investigate and confirm these findings.
在癌症研究领域，对坏死的关注较少，而专注于细胞凋亡的研究却很多。在神经肿瘤学中，这尤其令人惊讶，因为坏死作为胶质母细胞瘤（GBM）的一个标志具有重要意义，GBM是最恶性且最常见的原发性脑肿瘤，而且坏死程度已被证明与患者生存率呈负相关。因此，识别与坏死形成相关的基因和基因产物具有相当大的研究意义和重要性。
我们使用尼龙cDNA微阵列分析了15例手术切除的、具有不同坏死程度的人类GBM样本中588个通用细胞基因的mRNA表达。使用秩相关系数将基因表达与坏死程度进行关联。将鉴定出的基因在5例间变性星形细胞瘤（AA）组织样本中的表达与其在GBM样本中的表达进行比较。采用免疫染色来确定与坏死呈最正相关的基因是否随着坏死程度的增加而在肿瘤组织中表达增加。
杂交结果表明，26个基因与坏死量呈显著相关。所有26个基因的功能均与Ras、Akt、肿瘤坏死因子α、核因子κB、细胞凋亡、促凝血或缺氧相关。9个基因与坏死程度呈正相关，17个基因与坏死程度呈负相关。26个基因中的3个基因在III级坏死GBM和间变性星形细胞瘤（AA）样本之间的中位表达水平存在显著差异；与AA样本相比，在比较III级坏死时，除1个基因外，所有基因的表达均升高。由于其特别高的（正）相关系数，两个此前未在此背景下被考虑的因子—— Ephrin A型受体1和前列腺素E(2)受体EP4亚型被凸显出来；免疫染色显示这两个基因的产物定位于坏死周边和坏死区域，并且在III级GBM中过表达，但在AA中未过表达。在一个联合模型中，这两个分子也与GBM患者的生存率显著相关（P = 0.0034）。
cDNA表达微阵列分析的应用已经鉴定出了特定的基因和基因表达模式，这可能有助于阐明GBM中坏死发生的分子基础。还需要进一步的研究来进一步调查和证实这些发现。
