Servicio de Otorrinolaringología, Hospital Donosita, San Sebastian, Spain.
Otol Neurotol. 2011 Jan;32(1):163-70. doi: 10.1097/MAO.0b013e3182009665.
To determine the expression of the tyrosine kinases platelet-derived growth factor receptor (PDGFR) and c-Kit in vestibular schwannoma (VS) and to determine the potential role of imatinib mesylate (Gleevec) in regulating the growth and cell death of this tumor.
Protein tyrosine kinases are transmembrane tyrosine kinase receptors that transduce signals from inside and outside the cell and function as relay points for signaling pathways. They have a key role in numerous processes that affect cell proliferation, tumorigenesis, cancer invasion, metastasis, and modulation of apoptosis. A few of these kinases have been demonstrated to be overexpressed and dysregulated in many carcinomas, sarcomas, and benign tumors.
Immunohistochemical staining was used to investigate the expression of PDGFR and c-Kit in archived acoustic neuroma tissue. Clinical data including size of tumors, age, sex, and symptoms were correlated with kinase expression, whereas Western blot analysis and immunofluorescence were performed to demonstrate the expression and localization of PDGFR and c-Kit in HEI193, an immortalized VS cell line. Clonogenic survival assays were performed to assess proliferation inhibition by Gleevec. Gleevec's effect on the cell cycle profile also was investigated via flow cytometry analysis.
Expression of PDGFR in the formalin-fixed VS tumor tissue was observed in 23 (67.5%) of the 34 samples. C-kit was expressed in 18 (52.9%) of the 34 samples. Western blot analysis demonstrates positive expression of c-Kit and PDGFR-Q in HEI193 and a primary VS culture. Western blot analysis showed downregulation of phospho-c-kit and phospho-PDGFR-Q with 5 and 10 uM Gleevec. Immunofluorescent staining of this cell line also reveals that PDGFR-β is localized primarily in the cytoplasm, whereas c-Kit is both nuclear and cytoplasmic. Cell cycle analysis of HEI193 96 hours after incubation with Gleevec indicates a dose-dependent increase in G1 from 61.6% to 70.7% and 74% at 5 and 10 uM of Gleevec, respectively. Colony formation assays demonstrate dose-dependent growth inhibition by Gleevec, in the HEI193 cell line as well as in a VS cell culture derived from a fresh tumor.
The expression of PDGFR-Q and c-Kit in VS tissue may indicate novel molecular targets involved in the development of this tumor. Direct inhibition of these molecules by Gleevec may have relevant therapeutic applications.
确定酪氨酸激酶血小板衍生生长因子受体（PDGFR）和 c-Kit 在前庭神经鞘瘤（VS）中的表达，并确定甲磺酸伊马替尼（Gleevec）在调节这种肿瘤的生长和细胞死亡中的潜在作用。
蛋白酪氨酸激酶是跨膜酪氨酸激酶受体，可将细胞内外的信号转导，并作为信号通路的中继点发挥作用。它们在影响细胞增殖、肿瘤发生、癌症侵袭、转移和凋亡调节的许多过程中起着关键作用。其中一些激酶已被证明在许多癌肉瘤和良性肿瘤中过度表达和失调。
使用免疫组织化学染色来研究存档听神经瘤组织中 PDGFR 和 c-Kit 的表达。将临床数据（包括肿瘤大小、年龄、性别和症状）与激酶表达相关联，同时进行 Western blot 分析和免疫荧光分析，以证明 PDGFR 和 c-Kit 在 HEI193 中的表达和定位，HEI193 是一种永生化的 VS 细胞系。克隆存活测定用于评估 Gleevec 对增殖的抑制作用。还通过流式细胞术分析研究了 Gleevec 对细胞周期谱的影响。
在 34 个样本中的 23 个（67.5%）福尔马林固定的 VS 肿瘤组织中观察到 PDGFR 的表达。在 34 个样本中的 18 个（52.9%）中检测到 c-Kit 的表达。Western blot 分析表明 HEI193 和原发性 VS 培养物中 c-Kit 和 PDGFR-Q 的阳性表达。Western blot 分析显示，用 5 和 10 uM Gleevec 处理后，磷酸化 c-kit 和磷酸化 PDGFR-Q 的表达下调。该细胞系的免疫荧光染色也表明 PDGFR-β 主要定位于细胞质中，而 c-Kit 则位于核质中。用 Gleevec 孵育 HEI193 96 小时后的细胞周期分析表明，在 5 和 10 uM 的 Gleevec 下，G1 分别从 61.6%增加到 70.7%和 74%。集落形成测定表明，Gleevec 对 HEI193 细胞系以及源自新鲜肿瘤的 VS 细胞培养物的生长具有剂量依赖性抑制作用。
VS 组织中 PDGFR-Q 和 c-Kit 的表达可能表明该肿瘤发生过程中涉及的新的分子靶点。Gleevec 对这些分子的直接抑制可能具有相关的治疗应用。
