Showeil Rania, Romano Claudia, Valganon Mikel, Lambros Maryou, Trivedi Pritesh, Van Noorden Susan, Sriraksa Ruethairat, El-Kaffash Dalal, El-Etreby Nour, Natrajan Rachael, Foroni Letizia, Osborne Richard, El-Bahrawy Mona
Department of Histopathology, Imperial College London, London, United Kingdom.
Department of Clinical Pathology, Faculty of Medicine, Alexandria University, Alexandria, Egypt.
Oncotarget. 2016 Mar 1;7(9):10568-77. doi: 10.18632/oncotarget.7257.
The majority of borderline ovarian tumours (BOTs) behave in a benign fashion, but some may show aggressive behavior. The reason behind this has not been elucidated. The epidermal growth factor receptor (EGFR) is known to contribute to cell survival signals as well as metastatic potential of some tumours. EGFR expression and gene status have not been thoroughly investigated in BOTs as it has in ovarian carcinomas. In this study we explore protein expression as well as gene mutations and amplifications of EGFR in BOTs in comparison to a subset of other epithelial ovarian tumours. We studied 85 tumours, including 61 BOTs, 10 low grade serous carcinomas (LGSCs), 9 high grade serous carcinomas (HGSCs) and 5 benign epithelial tumours. EGFR protein expression was studied using immunohistochemistry. Mutations were investigated by Sanger sequencing exons 18-21 of the tyrosine kinase domain of EGFR. Cases with comparatively higher protein expression were examined for gene amplification by chromogenic in situ hybridization. We also studied the tumours for KRAS and BRAF mutations. Immunohistochemistry results revealed both cytoplasmic and nuclear EGFR expression with variable degrees between tumours. The level of nuclear localization was relatively higher in BOTs and LGSCs as compared to HGSCs or benign tumours. The degree of nuclear expression of BOTs showed no significant difference from that in LGSCs (mean ranks 36.48, 33.05, respectively, p=0.625), but was significantly higher than in HGSCs (mean ranks: 38.88, 12.61 respectively, p< 0.001) and benign tumours (mean ranks: 35.18, 13.00 respectively, p= 0.010). Cytoplasmic expression level was higher in LGSCs. No EGFR gene mutations or amplification were identified, yet different polymorphisms were detected. Five different types of point mutations in the KRAS gene and the V600E BRAF mutation were detected exclusively in BOTs and LGSCs. Our study reports for the first time nuclear localization of EGFR in BOTs. The nuclear localization similarities between BOTs and LGSCs and not HGSCs support the hypothesis suggesting evolution of LGSCs from BOTs. We also confirm that EGFR mutations and amplifications are not molecular events in the pathogenesis of BOTs.
大多数卵巢交界性肿瘤（BOTs）呈良性行为，但有些可能表现出侵袭性。其背后的原因尚未阐明。已知表皮生长因子受体（EGFR）有助于细胞存活信号以及某些肿瘤的转移潜能。与卵巢癌不同，EGFR在BOTs中的表达和基因状态尚未得到充分研究。在本研究中，我们探讨了BOTs中EGFR的蛋白表达以及基因突变和扩增情况，并与其他上皮性卵巢肿瘤的一个子集进行了比较。我们研究了85个肿瘤，包括61个BOTs、10个低级别浆液性癌（LGSCs）、9个高级别浆液性癌（HGSCs）和5个良性上皮性肿瘤。使用免疫组织化学研究EGFR蛋白表达。通过对EGFR酪氨酸激酶结构域的第18 - 21外显子进行桑格测序来研究突变。对蛋白表达相对较高的病例通过显色原位杂交检测基因扩增。我们还研究了肿瘤中的KRAS和BRAF突变。免疫组织化学结果显示，肿瘤之间EGFR的细胞质和细胞核表达程度各不相同。与HGSCs或良性肿瘤相比，BOTs和LGSCs中细胞核定位水平相对较高。BOTs的细胞核表达程度与LGSCs无显著差异（平均秩分别为36.48、33.05，p = 0.625），但显著高于HGSCs（平均秩分别为：38.88、12.61，p < 0.001）和良性肿瘤（平均秩分别为：35.18、13.00，p = 0.010）。LGSCs中的细胞质表达水平较高。未发现EGFR基因突变或扩增，但检测到不同的多态性。在BOTs和LGSCs中仅检测到KRAS基因的五种不同类型的点突变和V600E BRAF突变。我们的研究首次报道了BOTs中EGFR的细胞核定位。BOTs与LGSCs而非HGSCs之间的细胞核定位相似性支持了LGSCs由BOTs演变而来的假说。我们还证实EGFR突变和扩增不是BOTs发病机制中的分子事件。
