Introduction

Despite advanced diagnostic and therapeutic techniques, many brain tumors are still diagnosed at high grades and, therefore finding novel molecular markers may assist in early detection and reducing brain tumors-related mortality rate. Owing to the previous reports on the importance of MCPH1 gene in tumorigenesis, the present study was aimed to study the promoter methylation of MCPH1 gene in paired circulating cell-free DNA (cfDNA) and tumor tissues of brain tumor patients.

Materials and methods

Fourteen fresh paired serum and tumor tissue samples in addition to 18 isolated serum samples were collected from patients affected by different grades of brain tumor. Genomic DNA and cfDNA was isolated from tissue and serum samples using QIAamp DNA Mini Kit Norgen Bioteck Kit, respectively. Methylation DNA immunoprecipitation Real-time polymerization chain reaction (MeDIP-Real-time PCR) was performed on isolated DNA samples using EpiQuik MeDIP Ultra Kit and specific primer pairs. cfDNA quantity was determined through Real-time PCR analysis using specific primer pairs designed for GAPDH gene.

Results

MCPH1 was methylated in 54% of cfDNA samples which was significantly associated with tumor grade, as well (P-value = 0.02). The methylation rate of MCPH1 was found as 78% in the tissue samples which was meaningfully associated with tumor grade (P-value = 0.03). Moreover, methylation of the MCPH1 gene was consistent in 57% of the same cfDNA and tissue samples. Methylation of MCPH1 gene in neither tumor tissues nor cfDNA was not correlated with age and sex of the patients.

Discussion and conclusion

Due to the conformity of methylation of MCPH1 gene in cfDNA and tissue samples in more than half of the enrolled patients, especially in higher grades of tumors, it seems that MCPH1 promoter methylation could be a potential epimarker in not only detection of brain tumors but also in response to chemo- and radiotherapy which warranted further assessment.

中文翻译：

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脑肿瘤患者循环游离DNA中MCPH1基因启动子甲基化的研究。

介绍

尽管有先进的诊断和治疗技术，但许多脑肿瘤仍被诊断为高等级，因此寻找新的分子标志物可能有助于早期发现和降低脑肿瘤相关死亡率。由于先前关于MCPH1基因在肿瘤发生中的重要性的报道，本研究旨在研究MCPH1基因在配对循环游离细胞 DNA (cfDNA) 和脑肿瘤患者肿瘤组织中的启动子甲基化。

材料和方法

除了 18 份分离的血清样本外，还从受不同级别脑肿瘤影响的患者收集了 14 份新鲜配对的血清和肿瘤组织样本。分别使用 QIAamp DNA Mini Kit Norgen Bioteck Kit 从组织和血清样本中分离基因组 DNA 和 cfDNA。甲基化 DNA 免疫沉淀 使用 EpiQuik MeDIP Ultra Kit 和特异性引物对对分离的 DNA 样品进行实时聚合链式反应 (MeDIP-Real-time PCR)。使用为GAPDH基因设计的特定引物对通过实时 PCR 分析确定 cfDNA 数量。

结果

54% 的 cfDNA 样本中MCPH1被甲基化，这也与肿瘤分级显着相关（P值 = 0.02）。在组织样本中发现MCPH1的甲基化率为78%，与肿瘤分级显着相关（P值= 0.03）。此外，57% 的相同 cfDNA 和组织样本中MCPH1基因的甲基化是一致的。肿瘤组织和 cfDNA 中MCPH1基因的甲基化与患者的年龄和性别无关。

讨论和结论

由于半数以上入选患者的 cfDNA 和组织样本中MCPH1基因甲基化的一致性，特别是在更高级别的肿瘤中，似乎MCPH1启动子甲基化不仅可以作为脑肿瘤检测的潜在标志物，而且还可以作为以应对需要进一步评估的化学和放射治疗。