Molecular Targeting Unit, Fondazione IRCCS Istituto Nazionale dei Tumori, 20133, Milan, Italy.
Start Up Unit, Fondazione IRCCS Istituto Nazionale dei Tumori, 20133, Milan, Italy.
BMC Cancer. 2018 May 23;18(1):586. doi: 10.1186/s12885-018-4500-9.
CDCP1, a transmembrane protein with tumor pro-metastatic activity, was recently identified as a prognostic marker in TNBC, the most aggressive breast cancer subtype still lacking an effective molecular targeted therapy. The mechanisms driving CDCP1 over-expression are not fully understood, although several stimuli derived from tumor microenvironment, such as factors present in Wound Healing Fluids (WHFs), reportedly increase CDCP1 levels.
The expression of CDCP1, PDGFRβ and ERK1/2cell was tested by Western blot after stimulation of MDA-MB-231 cells with PDGF-BB and, similarly, in presence or not of ERK1/2 inhibitor in a panel of TNBC cell lines. Knock-down of PDGFRβ was established in MDA-MB-231 cells to detect CDCP1 upon WHF treatment. Immunohistochemical staining was used to detect the expression of CDCP1 and PDGFRβ in TNBC clinical samples.
We discovered that PDGF-BB-mediated activation of PDGFRβ increases CDCP1 protein expression through the downstream activation of ERK1/2. Inhibition of ERK1/2 activity reduced per se CDCP1 expression, evidence strengthening its role in CDCP1 expression regulation. Knock-down of PDGFRβ in TNBC cells impaired CDCP1 increase induced by WHF treatment, highlighting the role if this receptor as a central player of the WHF-mediated CDCP1 induction. A significant association between CDCP1 and PDGFRβ immunohistochemical staining was observed in TNBC specimens, independently of CDCP1 gene gain, thus corroborating the relevance of the PDGF-BB/PDGFRβ axis in the modulation of CDCP1 expression.
We have identified PDGF-BB/PDGFRβ-mediated pathway as a novel player in the regulation of CDCP1 in TNCBs through ERK1/2 activation. Our results provide the basis for the potential use of PDGFRβ and ERK1/2 inhibitors in targeting the aggressive features of CDCP1-positive TNBCs.
CDCP1 是一种具有肿瘤促转移活性的跨膜蛋白，最近被鉴定为三阴性乳腺癌（TNBC）的一种预后标志物，这是一种最具侵袭性的乳腺癌亚型，仍然缺乏有效的分子靶向治疗。虽然有研究表明，肿瘤微环境中衍生的多种刺激物，如创伤愈合液（WHF）中的因子，可增加 CDCP1 水平，但驱动 CDCP1 过表达的机制尚不完全清楚。
通过 Western blot 检测 PDGF-BB 刺激 MDA-MB-231 细胞后，以及在 TNBC 细胞系中存在或不存在 ERK1/2 抑制剂的情况下，检测 CDCP1、PDGFRβ 和 ERK1/2 细胞的表达。在 MDA-MB-231 细胞中建立 PDGFRβ 敲低，以检测 WHF 处理后 CDCP1 的表达。采用免疫组织化学染色检测 TNBC 临床样本中 CDCP1 和 PDGFRβ 的表达。
我们发现 PDGF-BB 介导的 PDGFRβ 激活通过下游 ERK1/2 的激活增加 CDCP1 蛋白表达。ERK1/2 活性的抑制本身降低了 CDCP1 的表达，这进一步证明了其在 CDCP1 表达调控中的作用。在 TNBC 细胞中敲低 PDGFRβ 可削弱 WHF 处理诱导的 CDCP1 增加，突出了该受体作为 WHF 介导的 CDCP1 诱导的核心参与者的作用。在 TNBC 标本中观察到 CDCP1 和 PDGFRβ 免疫组织化学染色之间存在显著关联，与 CDCP1 基因增益无关，因此证实了 PDGF-BB/PDGFRβ 轴在调节 CDCP1 表达中的相关性。
我们已经确定 PDGF-BB/PDGFRβ 介导的途径是通过 ERK1/2 激活调节 TNBC 中 CDCP1 表达的新途径。我们的研究结果为 PDGFRβ 和 ERK1/2 抑制剂在靶向 CDCP1 阳性 TNBC 的侵袭性特征方面的潜在应用提供了依据。
