Microvascular and Molecular Neuro-oncology Laboratory, New York University Langone Medical Center, New York, NY, USA.
BMC Cancer. 2013 Jul 17;13:347. doi: 10.1186/1471-2407-13-347.
Glioblastomas, the most common and malignant brain tumors of the central nervous system, exhibit high invasive capacity, which hinders effective therapy. Therefore, intense efforts aimed at improved therapeutics are ongoing to delineate the molecular mechanisms governing glioma cell migration and invasion.
In order to perform the studies, we employed optimal cell culture methods and hypoxic conditions, lentivirus-mediated knockdown of protein expression, Western Blot analysis, migration assays and immunoprecipitation. We determined statistical significance by unpaired t-test.
In this report, we show that U87MG, LN229 and LN308 glioma cells express CXCR7 and that exposure to hypoxia upregulates CXCR7 protein expression in these cell lines. CXCR7-expressing U87MG, LN229 and LN308 glioma cells migrated towards stromal-derived factor (SDF)-1α/CXCL12 in hypoxic conditions in the Boyden chamber assays. While shRNA-mediated knockdown of CXCR7 expression did not affect the migration of any of the three cell lines in normoxic conditions, we observed a reduction in the migration of LN229 and LN308, but not U87MG, glioma cells towards SDF-1α in hypoxic conditions. In addition, knockdown of CXCR7 expression in LN229 and LN308 glioma cells decreased levels of SDF-1α-induced phosphorylation of ERK1/2 and Akt. Inhibiting CXCR4 in LN229 and LN308 glioma cells that were knocked down for CXCR7 did not further reduce migration towards SDF-1α in hypoxic conditions and did not affect the levels of phosphorylated ERK1/2 and Akt. Analysis of immunoprecipitated CXCR4 from LN229 and LN308 glioma cells revealed co-precipitated CXCR7.
Taken together, our findings indicate that both CXCR4 and CXCR7 mediate glioma cell migration towards SDF-1α in hypoxic conditions and support the development of therapeutic agents targeting these receptors.
神经胶质瘤是中枢神经系统中最常见和最恶性的脑肿瘤，表现出高侵袭性，这阻碍了有效的治疗。因此，正在进行激烈的努力，以改善治疗方法，以描绘控制神经胶质瘤细胞迁移和侵袭的分子机制。
为了进行这些研究，我们采用了最佳的细胞培养方法和缺氧条件、慢病毒介导的蛋白表达敲低、Western Blot 分析、迁移实验和免疫沉淀。我们通过未配对的 t 检验确定了统计学意义。
在本报告中，我们表明 U87MG、LN229 和 LN308 神经胶质瘤细胞表达 CXCR7，并且缺氧暴露上调这些细胞系中 CXCR7 蛋白的表达。在 Boyden 室测定中，CXCR7 表达的 U87MG、LN229 和 LN308 神经胶质瘤细胞在缺氧条件下向基质衍生因子（SDF）-1α/CXCL12 迁移。虽然 shRNA 介导的 CXCR7 表达敲低不影响这三种细胞系在常氧条件下的迁移，但我们观察到 LN229 和 LN308 但不是 U87MG 神经胶质瘤细胞向 SDF-1α的迁移减少在缺氧条件下。此外，LN229 和 LN308 神经胶质瘤细胞中 CXCR7 表达敲低降低了 SDF-1α 诱导的 ERK1/2 和 Akt 磷酸化水平。在 LN229 和 LN308 神经胶质瘤细胞中敲低 CXCR7 后抑制 CXCR4 并不能进一步减少缺氧条件下对 SDF-1α的迁移，也不能影响磷酸化 ERK1/2 和 Akt 的水平。从 LN229 和 LN308 神经胶质瘤细胞中免疫沉淀的 CXCR4 的分析表明，共沉淀的 CXCR7。
总之，我们的研究结果表明，CXCR4 和 CXCR7 均介导神经胶质瘤细胞在缺氧条件下向 SDF-1α 的迁移，并支持开发针对这些受体的治疗剂。
