Allelic losses of the q13.3 region of chromosome 19 have been documented in all major types of diffuse gliomas, strongly suggesting the presence of a 19q13.3 tumor suppressor gene responsible for these malignancies. The P⁷⁸ gene precisely maps to 19q13.3, the glioma candidate region, and encodes a recently identified novel protein (P⁷⁸). The purpose of this study was to determine P⁷⁸ protein expression in gliomas. Serial analysis of gene expression (SAGE) reveals P⁷⁸ mRNA expression to be significantly reduced in high-grade gliomas such as glioblastoma (GB), as compared with the low-grade tumors including astrocytomas, oligodendrogliomas, and ependymomas. We observed the distribution of staining of P⁷⁸ protein was concentrated on the cell membranes of the luminal epithelial cells, not cytoplasm. In contrast, the pre-immune serum controls demonstrated no staining. These results demonstrate that P⁷⁸ protein is highly expressed in the cytoplasmic membranes of low but not high-grade astrocytomas, and correlates with grade of malignancy. In these double immunostaining experiments, the anti-Map-2 and anti-NeuN antibodies did not stain round cells that were stained with the anti-P⁷⁸ carboxyl-terminal peptide antibodies, demonstrating that these round cells were not neurons, and likely protoplasmic astrocytes. Current results also suggest that the astrocytes stained with the anti-P⁷⁸ carboxyl-terminal peptide antibody are likely protoplasmic astrocytes. We also observed preincubation of anti-P⁷⁸ carboxyl-terminal antibodies with immunizing peptides abolished immunostaining in gliomas. These results suggest a role for the P⁷⁸ protein in the process of abnormal growth in glial tumors.

中文翻译：

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P78的分析：胶质瘤标本中的染色体19q13.3上编码的新型细胞质膜相关蛋白。

在所有主要类型的弥漫性神经胶质瘤中均已记录了19号染色体q13.3区的等位基因缺失，强烈提示存在导致这些恶性肿瘤的19q13.3肿瘤抑制基因。P ⁷⁸基因精确地映射到神经胶质瘤候选区域19q13.3，并编码最近鉴定的新蛋白（P ⁷⁸）。这项研究的目的是确定神经胶质瘤中P ⁷⁸蛋白的表达。基因表达的序列分析（SAGE）显示，与星形胶质瘤，少突胶质细胞瘤和室管膜瘤等低度肿瘤相比，高级别神经胶质瘤（例如胶质母细胞瘤（GB））中P ⁷⁸ mRNA表达显着降低。我们观察到P ⁷⁸染色的分布蛋白质集中在腔上皮细胞的细胞膜上，而不是细胞质上。相反，免疫前血清对照显示无染色。这些结果表明，P ⁷⁸蛋白在低度而非高度星形细胞瘤的细胞质膜中高表达，并且与恶性程度相关。在这些双重免疫染色实验中，抗Map-2和抗NeuN抗体未染色被抗P ⁷⁸羧基末端肽抗体染色的圆形细胞，表明这些圆形细胞不是神经元，可能不是原生质星形胶质细胞。目前的结果还表明，星形胶质细胞被抗P ⁷⁸染色羧基末端肽抗体可能是原生质星形胶质细胞。我们还观察到抗-P ⁷⁸羧基末端抗体与免疫肽的预孵育消除了神经胶质瘤中的免疫染色。这些结果表明P ⁷⁸蛋白在神经胶质瘤异常生长过程中的作用。