Department of Medicine, Hematology and Oncology, University Hospital Muenster, D-48129 Muenster, Germany.
Int J Oncol. 2012 Oct;41(4):1455-63. doi: 10.3892/ijo.2012.1548. Epub 2012 Jul 6.
Tumor cell invasion and metastasis are hallmarks of malignancy. Despite recent advances in the understanding of lymphatic spread, the mechanisms by which tumors metastasize to sentinel/distant lymph nodes and beyond are poorly understood. To gain new insights into this complex process, we established highly metastatic melanoma cell lines by in vivo passaging the B16 parental cell line through the lymphatic system. In this study we characterized morphology, rate of cell proliferation, colony formation, migration, tumorigenicity, lymph flow, and capacities to induce tumor- and sentinel lymph node-lymphangiogenesis. Furthermore, microarray-based comparative analysis between parental and passaged cell lines was performed to identify specific gene expression profiles. The most differentially expressed gene was SPP (osteopontin), a secreted glycophosphoprotein which is known to be involved in cancer metastasis. Overexpression of osteopontin in B16 F1-variant was confirmed by western blot analysis and quantitative RT-PCR. Treatment of cultured lymphatic endothelial cells (LECs) with osteopontin promoted cell migration mediated by the integrin α9 pathway. Our results identify osteopontin as a novel lymphangiogenic factor.
肿瘤细胞的侵袭和转移是恶性肿瘤的特征。尽管近年来对淋巴扩散机制的理解取得了进展，但肿瘤转移到前哨/远处淋巴结及更远部位的机制仍知之甚少。为了深入了解这一复杂过程，我们通过体内途径将 B16 亲本细胞系经淋巴系统传代，建立了高转移性黑色素瘤细胞系。在这项研究中，我们对形态、细胞增殖速度、集落形成、迁移、致瘤性、淋巴流动以及诱导肿瘤和前哨淋巴结淋巴管生成的能力进行了表征。此外，我们还对亲本和传代细胞系进行了基于微阵列的比较分析，以确定特定的基因表达谱。差异表达最显著的基因是 SPP（骨桥蛋白），这是一种已知参与癌症转移的分泌糖蛋白。通过 Western blot 分析和定量 RT-PCR 证实 B16 F1 变体中转录本水平的骨桥蛋白过表达。骨桥蛋白处理培养的淋巴管内皮细胞（LEC）可促进整合素 α9 通路介导的细胞迁移。我们的研究结果确定骨桥蛋白为一种新型的淋巴管生成因子。
