Breast Cancer Anti-Estrogen Resistance 4 (BCAR4) Drives Proliferation of IPH-926 lobular Carcinoma Cells.
Breast Cancer Anti-Estrogen Resistance 4 (BCAR4) Drives Proliferation of IPH-926 lobular Carcinoma Cells.
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DOI：
10.1371/journal.pone.0136845
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发表时间：
2015
期刊：
影响因子：
3.7
通讯作者：
Christgen M
中科院分区：
文献类型：
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作者：
van Agthoven T;Dorssers LC;Lehmann U;Kreipe H;Looijenga LH;Christgen M
大多数乳腺癌依赖于雌激素的生长刺激。在体外细胞模型中进行的功能性基因筛选已经确定了一些基因，这些基因可以克服抗雌激素药物（如他莫昔芬）诱导的生长抑制。使用这种方法，我们以前已经确定了乳腺癌抗雌激素抵抗4（BCAR 4）作为细胞增殖和他莫昔芬耐药性的介导者。在这里，我们显示了BCAR 4在人类乳腺癌中的高水平表达和功能。 在一组人正常组织、原发性乳腺癌和细胞系中通过（q）RT-PCR评估BCAR 4 mRNA表达。一种针对推定的BCAR 4蛋白的C78-I97产生的新抗体，用于蛋白质印迹和免疫沉淀测定。此外，实施siRNA介导的基因沉默以研究BCAR 4及其下游靶点ERBB 2/3的功能。除胎盘外，所有检测的人体正常组织均为BCAR 4阴性。在原发性乳腺癌中，BCAR 4表达相对罕见（10%），但与增殖增强相关。在IPH-926中鉴定了相对高的BCAR 4 mRNA表达，IPH-926是一种源自内分泌抵抗性小叶乳腺癌的细胞系。中度BCAR 4表达在MDA-MB-134和MDA-MB-453乳腺癌细胞中明显。在具有异位（ZR-75-1-BCAR 4）和内源性（IPH-926，MDA-MB-453）BCAR 4 mRNA表达的乳腺癌细胞中检测到BCAR 4蛋白。BCAR 4的敲低抑制细胞增殖。在ERBB 2/3敲低和暴露于拉帕替尼后观察到类似的效应，这意味着BCAR 4以ERBB 2/3依赖性方式起作用。 BCAR 4编码一种功能性蛋白质，可驱动内分泌抵抗性乳腺癌细胞的增殖。拉帕替尼是一种临床批准的EGFR/ERBB 2抑制剂，可抵消BCAR 4驱动的肿瘤细胞生长，这是一项临床相关观察结果。
Most breast cancers depend on estrogenic growth stimulation. Functional genetic screenings in in vitro cell models have identified genes, which override growth suppression induced by anti-estrogenic drugs like tamoxifen. Using that approach, we have previously identified Breast Cancer Anti-Estrogen Resistance 4 (BCAR4) as a mediator of cell proliferation and tamoxifen-resistance. Here, we show high level of expression and function of BCAR4 in human breast cancer. BCAR4 mRNA expression was evaluated by (q)RT-PCR in a panel of human normal tissues, primary breast cancers and cell lines. A new antibody raised against C78-I97 of the putative BCAR4 protein and used for western blot and immunoprecipitation assays. Furthermore, siRNA-mediated gene silencing was implemented to study the function of BCAR4 and its downstream targets ERBB2/3. Except for placenta, all human normal tissues tested were BCAR4-negative. In primary breast cancers, BCAR4 expression was comparatively rare (10%), but associated with enhanced proliferation. Relative high BCAR4 mRNA expression was identified in IPH-926, a cell line derived from an endocrine-resistant lobular breast cancer. Moderate BCAR4 expression was evident in MDA-MB-134 and MDA-MB-453 breast cancer cells. BCAR4 protein was detected in breast cancer cells with ectopic (ZR-75-1-BCAR4) and endogenous (IPH-926, MDA-MB-453) BCAR4 mRNA expression. Knockdown of BCAR4 inhibited cell proliferation. A similar effect was observed upon knockdown of ERBB2/3 and exposure to lapatinib, implying that BCAR4 acts in an ERBB2/3-dependent manner. BCAR4 encodes a functional protein, which drives proliferation of endocrine-resistant breast cancer cells. Lapatinib, a clinically approved EGFR/ERBB2 inhibitor, counteracts BCAR4-driven tumor cell growth, a clinical relevant observation.