Abstract

Introduction: Metastasis to the brain and bone is a major source of morbidity and mortality in cancer patients. We report genetic profiling of brain- and bone-selective invasive and metastatic MDA-MB-231 breast cancer cells using cDNA Array technology and real-time RT-PCR. Methods: Gene profiling was performed using the 16 K gene chip of the National Human Genome Research Institute, NIH, USA. Results were verified by quantative real-time RT-PCR. Protein expression was examined using enzymelinked immunosorbent assays (ELISA) and western blotting. Migration and invasion assays were performed with the QCM 96-well Migration/Invasion Assay +/– specific MMP inhibitors. Results: cDNA array analysis revealed significant over- or underexpression in brain- and / or bone-seeking cells of 113 genes. 9 gene sequences were chosen for data validation using real-time RT-PCR. Herein, significant changes in both selective clones were found for: (1) matrix-metallo-proteinase 1 (MMP-1), (3) the metastasis suppressor gene KISS-1 and (2) vascular factors endoglin and TIE-1. These genes were chosen for further analysis. Functional experiments determined the potential role for breast cancer metastasis to the brain and bone. In vitro experiments were supplemented by examinations on human tumor tissue. Herein, (1) the expression of MMP-1 and MMP-9 was increased in brain-metastatic cells (mRNA and -protein level). (2) We found significantly decreased expression of metastases suppressor genes in human breast cancer brain metastases: KISS-1, BRMS-1, MKK4, KAI-1 and Maspin (SERPINB5). Conclusion: (1) MMP-1 and -9 were overexpressed in brain-seeking 231-clones. MMP-1 and -9 inhibitors lead to decreased invasive and migratory potential in vitro. (2) Several metastasis-suppressor genes, including Maspin (SERPIN B5) were decreased in human breast cancer brain metastases.