Suzuki Ayumi, Okuda Katsuhiro, Yano Motoki, Oda Risa, Sakane Tadashi, Kawano Osamu, Haneda Hiroshi, Moriyama Satoru, Nakanishi Makoto, Nakanishi Ryoichi
Department of Oncology, Immunology and Surgery, Nagoya City University Graduate School of Medical Sciences, Mizuho, Nagoya 467-8601, Japan.
Division of Cancer Cell Biology, Department of Cancer Biology, The Institute of Medical Science, The University of Tokyo, Minato, Tokyo 108-8639, Japan.
Oncol Lett. 2017 Jul;14(1):891-898. doi: 10.3892/ol.2017.6216. Epub 2017 May 19.
Patients with smoking-independent lung cancer mainly consist of females, yet the molecular background of this epidemiological feature, other than epidermal growth factor receptor (EGFR) mutation, remains unclear. Several studies have revealed the association between female hormone-associated factors and the prognosis of lung cancer, however the data remain inconsistent. The present study focused on the expression of estrogen receptor (ER)α in order to elucidate this association in smoking-independent lung cancer. Immunohistochemistry staining (IHC) of aromatase, ERα and ERβ was performed against formalin-treated tissues from 38 patients who had never-smoked who underwent complete surgical resection between 2012 and 2013. Among them, adequate RNA of the tumor and adjacent normal lung cancer was extracted from 31 matching deep frozen samples. Considering the IHC results, reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was performed to measure the expression level of 2 different exons of ERα, exon 6 and exon 7, which are part of the ligand binding domain of ERα, using the Taqman gene expression assay. Extra-nuclear expression of ERα using IHC demonstrated a statistically significant association with pathological invasiveness. RT-qPCR results exhibited a decreased expression of ERα exon 7 in invasive tumor tissues, compared with their adjacent normal tissues. This is consistent with the findings of previous studies indicating that extra-nuclear ERα were exon 7 splicing variants. No difference was observed in ERα exon 7 expression between normal and tumor tissues in non-invasive lung cancer tissues. When considering the EGFR mutation status, EGFR wild-type lung cancers exhibited decreased ERα exon 7 expression levels compared with EGFR mutated lung cancers. Extra-nuclear expression of ERα, which may represent exon 7 splicing variants of ERα, showed statistical association with pathological invasiveness in smoking-independent lung cancer. The post-translational splicing mechanism of ERα may be involved in the acquired invasiveness of smoking independent lung cancer.
非吸烟相关性肺癌患者主要为女性，然而除表皮生长因子受体（EGFR）突变外，这一流行病学特征的分子背景仍不清楚。多项研究揭示了女性激素相关因素与肺癌预后之间的关联，但数据仍不一致。本研究聚焦于雌激素受体（ER）α的表达，以阐明非吸烟相关性肺癌中的这种关联。对2012年至2013年间接受完整手术切除的38例从不吸烟患者的福尔马林固定组织进行了芳香化酶、ERα和ERβ的免疫组织化学染色（IHC）。其中，从31对匹配的深度冷冻样本中提取了肿瘤及相邻正常肺组织的足量RNA。根据IHC结果，采用Taqman基因表达分析法进行逆转录定量聚合酶链反应（RT-qPCR），以检测ERα配体结合域的两个不同外显子（外显子6和外显子7）的表达水平。使用IHC检测到的ERα核外表达与病理侵袭性具有统计学意义的关联。RT-qPCR结果显示，与相邻正常组织相比，侵袭性肿瘤组织中ERα外显子7的表达降低。这与先前研究结果一致，表明核外ERα是外显子7剪接变体。在非侵袭性肺癌组织的正常组织和肿瘤组织之间，未观察到ERα外显子7表达的差异。考虑到EGFR突变状态，与EGFR突变的肺癌相比，EGFR野生型肺癌的ERα外显子7表达水平降低。ERα的核外表达可能代表ERα的外显子7剪接变体，在非吸烟相关性肺癌中与病理侵袭性具有统计学关联。ERα的翻译后剪接机制可能参与了非吸烟相关性肺癌的获得性侵袭性。
