Department of Radiation Oncology, The Ohio State University, Columbus, OH 43210, USA.
Radiat Oncol. 2013 Oct 23;8:246. doi: 10.1186/1748-717X-8-246.
Brain metastasis from breast cancer poses a major clinical challenge. Integrins play a role in regulating adhesion, growth, motility, and survival, and have been shown to be critical for metastatic growth in the brain in preclinical models. Cilengitide, an αvβ3/αvβ5 integrin inhibitor, has previously been studied as an anti-cancer drug in various tumor types. Previous studies have shown additive effects of cilengitide and radiation in lung cancer and glioblastoma cell lines. The ability of cilengitide to enhance the effects of radiation was examined preclinically in the setting of breast cancer to assess its possible efficacy in the setting of brain metastasis from breast cancer.
Our panel of breast cells was composed of four cell lines: T-47D (ER/PR+, Her2-, luminal A), MCF-7 (ER/PR+, Her2-, luminal A), MDA-MB-231 (TNBC, basal B), MDA-MB-468 (TNBC, basal A). The presence of cilengitide targets, β3 and β5 integrin, was first determined. Cell detachment was determined by cell counting, cell proliferation was determined by MTS proliferation assay, and apoptosis was measured by Annexin V staining and flow cytometry. The efficacy of cilengitide treatment alone was analyzed, followed by assessment of combined cilengitide and radiation treatment. Integrin β3 knockdown was performed, followed by cilengitide and radiation treatment to test for incomplete target inhibition by cilengitide, in high β3 expressing cells.
We observed that all cell lines examined expressed both β3 and β5 integrin and that cilengitide was able to induce cell detachment and reduced proliferation in our panel. Annexin V assays revealed that a portion of these effects was due to cilengitide-induced apoptosis. Combined treatment with cilengitide and radiation served to further reduce proliferation compared to either treatment alone. Following β3 integrin knockdown, radiosensitization in combination with cilengitide was observed in a previously non-responsive cell line (MDA-MB-231). Clonogenic assays suggested little radiosensitization effects of cilengitide.
Cilengitide appears to enhance radiation response in preclinical models of breast cancer. These data suggest that the combination of radiation therapy and cilengitide may prove to be effective where radiation is utilized for the treatment of gross disease in breast cancer, such as in the setting of brain metastasis.
乳腺癌脑转移是一个重大的临床挑战。整合素在调节黏附、生长、迁移和存活方面发挥作用，并且在临床前模型中被证明对脑转移的生长至关重要。西仑吉肽是一种 αvβ3/αvβ5 整合素抑制剂，之前已在各种肿瘤类型中作为抗癌药物进行了研究。先前的研究表明，西仑吉肽和放疗在肺癌和胶质母细胞瘤细胞系中具有相加作用。本研究在乳腺癌中评估了西仑吉肽增强放疗效果的能力，以评估其在乳腺癌脑转移中的可能疗效。
我们的乳腺癌细胞小组由四种细胞系组成：T-47D（ER/PR+，Her2-，腔 A）、MCF-7（ER/PR+，Her2-，腔 A）、MDA-MB-231（TNBC，基底 B）、MDA-MB-468（TNBC，基底 A）。首先确定了西仑吉肽的靶点β3 和β5 整合素的存在。通过细胞计数确定细胞脱落，通过 MTS 增殖测定确定细胞增殖，通过 Annexin V 染色和流式细胞术测量细胞凋亡。分析了西仑吉肽单独治疗的效果，然后评估了西仑吉肽联合放疗的效果。进行了整合素β3 敲低，然后用西仑吉肽和放疗进行治疗，以测试在高β3 表达细胞中，西仑吉肽不完全抑制靶标。
我们观察到所有检查的细胞系均表达β3 和β5 整合素，西仑吉肽能够诱导我们小组中的细胞脱落并减少增殖。Annexin V 检测表明，这些作用的一部分是由于西仑吉肽诱导的细胞凋亡。与单独治疗相比，西仑吉肽联合放疗进一步降低了增殖。在β3 整合素敲低后，在以前无反应的细胞系（MDA-MB-231）中观察到与西仑吉肽联合的放射增敏作用。集落形成试验表明，西仑吉肽对放疗的增敏作用很小。
西仑吉肽似乎增强了乳腺癌临床前模型中的辐射反应。这些数据表明，放射治疗联合西仑吉肽可能在用于治疗乳腺癌大体疾病（如脑转移）的放射治疗中证明是有效的。
