Pan Yi, Qi Xue-ling, Wang Lei-ming, Dong Rong-fang, Zhang Ming, Zheng Dan-feng, Chang Qing, Zhong Yan-feng
Department of Pathology, Peking University Health Science Center, Beijing, China.
Zhonghua Bing Li Xue Za Zhi. 2013 May;42(5):292-8. doi: 10.3760/cma.j.issn.0529-5807.2013.05.002.
To investigate mutation status of isocitrate dehydrogenase (IDH) 1 and IDH2 genes in Chinese patients with gliomas in correlation with clinicopathological characteristics.
Formalin-fixed and paraffin-embedded (FFPE) tissue samples of 234 gliomas were collected including the matched blood samples in 30 patients. DNA was extracted, followed by PCR-Sanger sequencing to detect IDH1 and IDH2 gene mutations. Immunohistochemistry was performed using mutation-specific antibody recognizing IDH1R132H mutation. Immunostains for p53 and epidermal growth factor receptor (EGFR) were also performed. Oligodendroglial tumors with IDH mutation were double stained with IDH1R132H and GFAP by immunofluorescence to investigate the location of IDH1R132H expression.
(1) By IDH1 heterozygous somatic mutation analysis, Arg132His (c: G395A) was found in 31.6% (74 of 234) of the cases. IDH mutations were more frequent in oligoastrocytomas (9/13), anaplastic oligoastrocytomas (7/11), oligodendrogliomas(18/26, 69.2%), anaplastic oligodendrogliomas (8/10), and less frequent in diffuse astrocytomas (17/47, 36.2%), anaplastic astrocytomas (5/18), and glioblastomas (10/69, 14.5%). The mutation rate inversely correlated with the tumor grade in a linear fashion in astrocytic tumors (P = 0.007). Primary glioblastomas were characterized by a lower frequency of mutations than secondary glioblastomas (5/55 vs. 5/14, P = 0.036); IDH mutation was not detected in pilocytic astrocytoma and ependymoma. No IDH2 mutation was identified in this study cohort. (2) Immunohistochemistry of IDH1R132H demonstrated a strong cytoplasmic staining in 80 cases, which was highly correlated with IDH mutation status (P = 0.001). IDH1R132H was highly specific to tumor cells. (3) p53 immunostain was significantly correlated the IDH mutation in diffuse astrocytoma, anaplastic astrocytoma and secondary glioblastomas (P = 0.007, 0.026, 0.038 respectively). (4) No correlation between EGFR and IDH mutation was found.
High prevalence of IDH heterozygous somatic mutation occurs in the earlier stage of gliomas, which can be detected by mutation-specific antibody IDH1R132H. Furthermore, evaluation of p53 and EGFR expression combined with IDH mutation analysis may significantly aid in the diagnosis and differential diagnoses of gliomas in Chinese patients.
探讨中国胶质瘤患者异柠檬酸脱氢酶（IDH）1和IDH2基因的突变状态及其与临床病理特征的相关性。
收集234例胶质瘤的福尔马林固定石蜡包埋（FFPE）组织样本，其中30例患者同时收集了配对的血液样本。提取DNA，随后进行PCR-Sanger测序以检测IDH1和IDH2基因突变。使用识别IDH1R132H突变的突变特异性抗体进行免疫组织化学检测。还进行了p53和表皮生长因子受体（EGFR）的免疫染色。对具有IDH突变的少突胶质细胞瘤进行IDH1R132H和GFAP免疫荧光双重染色，以研究IDH1R132H表达的位置。
（1）通过IDH1杂合体细胞突变分析，在31.6%（234例中的74例）的病例中发现了Arg132His（c：G395A）。IDH突变在少突星形细胞瘤（9/13）、间变性少突星形细胞瘤（7/11）、少突胶质细胞瘤（18/26，69.2%）、间变性少突胶质细胞瘤（8/10）中更常见，而在弥漫性星形细胞瘤（17/47，36.2%）、间变性星形细胞瘤（5/18）和胶质母细胞瘤（10/69，14.5%）中较少见。在星形细胞肿瘤中，突变率与肿瘤分级呈线性负相关（P = 0.007）。原发性胶质母细胞瘤的突变频率低于继发性胶质母细胞瘤（5/55对5/14，P = 0.036）；在毛细胞型星形细胞瘤和室管膜瘤中未检测到IDH突变。本研究队列中未鉴定出IDH2突变。（2）IDH1R132H的免疫组织化学显示80例中有强细胞质染色，与IDH突变状态高度相关（P = 0.001）。IDH1R132H对肿瘤细胞具有高度特异性。（3）在弥漫性星形细胞瘤、间变性星形细胞瘤和继发性胶质母细胞瘤中，p53免疫染色与IDH突变显著相关（分别为P = 0.007、0.026、0.038）。（4）未发现EGFR与IDH突变之间存在相关性。
IDH杂合体细胞突变在胶质瘤的早期阶段发生率较高，可通过突变特异性抗体IDH1R132H检测到。此外，结合IDH突变分析评估p53和EGFR表达可能有助于中国患者胶质瘤的诊断和鉴别诊断。
