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W HEN TUMOR CELLS metas- tasize, they have two ways to travel through the body: t he ly mphatic system or the bloodstream. The majority of tumor cells spread through lymph ves- sels, rather than blood vessels, and the view that certain cancers, including breast and prostate cancer, metasta- size through the lymphatic system is well-est ablished. However, less is known about the process tumor cells use to migrate to the lymphatic system. The Role of Inflammation Infl ammation is suspected of playing a part in regulating metastatic behavior. According to J. Steven Alexander, PhD, Professor in the Department of Molecular and Cellular Physiology at the LSU Health NEW RESEARCH IS SHEDDING LIGHT ON THE BIOCHEMICAL MECHANISMS THAT ALLOW TUMOR CELLS TO METASTASIZE VIA THE LYMPHATIC SYSTEM. SCIENTISTS HOPE ONE DAY THIS EXPANDED KNOWLEDGE WILL HELP THEM BLOCK THAT MEANS OF METASTASIS. Sciences Center, the lymphatic system serves a similar role in infl ammation and cancer — cells that leave infl amed tissues exit via the lymphatic system. Metastasizing tumor cells may also exploit some of the pathways used during inflammation. Additionally, tumor-infi ltrating immune cells secrete cytokines and proteases that may affect tumor cells by promot- ing epithelial-mesenchymal transition (EMT), says Jonas Fuxe, MD, PhD, Associate Professor in the Department of Medical Biochemistry and Biophysics at the Karolinska Institutet in Stockholm. EMT is a developmental process that typically is not active in adult tissues. "Reactivation of EMT in cancer and inflammation is due to an overexpres- sion of cytokines, such as TGF-β1," Dr. Fu xe notes. " Tumor cells t hat undergo EMT are known to acquire more invasive and migratory properties. Yet, it has not been crystal clear how these properties are used." Dr. Fuxe and an international team of researchers that included Alexander questioned whether tumor cells within the tumor microenvironment migrate randomly or if the metastatic process is regulated. Building on research pub- lished in 2009 in Nature Cell Biolog y, which found that TGF-β1 initiates single-cell motility and migration of mammary tumor cells, they hypoth- esized t hat TGF-β1-induced EMT promotes the migration of tumor cells to lymphatic vessels. The team's results, published online in May in Oncogene, show that in breast cancer patients, migratory mammary at the Lymphatic Pass? Metastasis By Tiffany Parnell Cutting Off SPECIAL CLINICAL SECTION: ONCOLOGY 2 4 | Long Island MD NEWS ■ M D N E W S . CO M