Immunohistochemical analysis of retinoblastoma cell phenotype using neuronal and glial cell markers

ABSTRACT Purpose: The cellular origin of retinoblastoma is uncertain as constituent tumor cells heterogeneously express markers of both immature and mature retinal cells. An immunohistochemical analysis of cellular origin may yield valuable insights into disease progression and treatment options. This study aimed to determine the cellular origin of retinoblastoma in a large case series and correlate these findings with histopathological prognostic factors. Methods: Thirty-nine retinoblastoma cases were histopathologically diagnosed and analyzed by immunohistochemistry using monoclonal antibodies against the immature neural cell marker SRY-box containing gene 2 (SOX-2), the mature neuronal cell marker microtubule-associated protein 2 (MAP2), and the mature glial cell marker glial fibrillary acidic protein (GFAP). Histopathological features were also evaluated, including patterns of growth, differentiation, vitreous seeding, and choroidal/scleral, optic nerve, and anterior chamber invasion. Two retinoblastoma cell lines, WERI-1 and Y79, were studied by immunocytochemistry using the same antibodies. Results: Expression of SOX-2 was strong in 97.4% of retinoblastoma cases, while MAP-2 was expressed in 59% of cases. Immunostaining for GFAP was positive only in reactive stromal astrocytes interspersed amongst tumor cells and in peritumoral tissue. There was no correlation between histopathological prognostic factors and immunohistochemical markers. Retinoblastoma cell lines showed strong positivity for SOX2 (90% of WERI-1 cells and 70% of Y79 cells) and MAP2 (90% of cells in both lines). GFAP was completely negative in both cell lines. Conclusion: The majority of retinoblastomas and both RB cell lines expressed an immature neural and/or a mature neuronal cell marker, but not a glial marker. These results indicate a typical neuroblast or neuronal origin and eliminate astrocyte differentiation from neural stem cells as the source of retinoblastoma.

摘要

目的：视网膜母细胞瘤的细胞起源尚不明确，因其肿瘤组成细胞异质性地表达未成熟与成熟视网膜细胞的标志物。针对细胞起源的免疫组织化学分析，或可为疾病进展研究与治疗方案选择提供有价值的参考。本研究旨在通过大样本病例系列明确视网膜母细胞瘤的细胞起源，并将上述发现与组织病理学预后因素进行关联分析。

方法：本研究对39例经组织病理学确诊的视网膜母细胞瘤病例开展免疫组织化学分析，所用单克隆抗体分别靶向未成熟神经细胞标志物SRY盒包含基因2（SRY-box containing gene 2，SOX-2）、成熟神经元细胞标志物微管相关蛋白2（microtubule-associated protein 2，MAP2）以及成熟胶质细胞标志物胶质纤维酸性蛋白（glial fibrillary acidic protein，GFAP）。同时评估多项组织病理学特征，包括生长模式、分化程度、玻璃体播种、脉络膜/巩膜侵袭、视神经侵袭及前房侵袭情况。此外，采用相同抗体对WERI-1与Y79两种视网膜母细胞瘤细胞系开展免疫细胞化学检测。

结果：97.4%的视网膜母细胞瘤病例呈SOX-2强阳性表达，59%的病例表达MAP2。GFAP免疫染色仅在肿瘤细胞间散在的反应性基质星形胶质细胞以及瘤周组织中呈阳性。未观察到组织病理学预后因素与免疫组织化学标志物之间存在相关性。视网膜母细胞瘤细胞系中，SOX2呈强阳性表达（WERI-1细胞系阳性率为90%，Y79细胞系为70%），MAP2在两种细胞系中均有90%的细胞呈阳性表达。两种细胞系的GFAP染色均完全呈阴性。

结论：多数视网膜母细胞瘤病例及两种视网膜母细胞瘤细胞系均表达未成熟神经细胞标志物和/或成熟神经元细胞标志物，但不表达胶质细胞标志物。上述结果提示，视网膜母细胞瘤起源于典型的神经母细胞或神经元细胞，排除了神经干细胞分化为星形胶质细胞作为其起源的可能性。