ABSTRACT
BACKGROUND: Lymphatic endothelial cells from primary lymphedema skin have never been cultured nor characterized. A subgroup of patients with primary lymphedema undergo surgery to bring about an improvement in their quality of life. The aim of this study was to culture and characterize LECs from the skin of these patients. METHODS AND RESULTS: Lymphatic endothelial cells were isolated and cultured from the skin of patients with primary lymphedema and from normal skin. The isolated cells were compared in their ability to form microvascular networks in a three-dimensional culture medium, and in their response to treatment with vascular endothelial growth factors A, C, and D. Whole tissue transcriptional profiling was carried out on two pools of isolated lymphatic endothelial cells--one from primary lymphedema skin and the other from normal skin. Lymphatic endothelial cells from primary lymphedema skin form tubule-like structures when cultured in three-dimensional media. They respond in a similar fashion to stimulation with the vascular endothelial growth factors A, C, and D. Comparative analysis between lymphedema tissue and normal tissue (fold change >2) showed differential expression of 2793 genes (5% of all transcripts), 2184 upregulated, and 609 downregulated. Genes involved in cellular apoptosis (vascular endothelial growth inhibitor, zinc finger protein), extracellular matrix turnover (matrix metalloproteinase inhibitor-16), and type IV collagen deposition were upregulated. Various pro-inflammatory genes (interleukin-6, interleukin-8, interleukin-32, E-selectin) were downregulated. CONCLUSION: Cellular adhesion, apoptosis, and increased extracellular matrix turnover play a more prominent role in primary lymphedema than previously thought. In addition, the acute inflammatory response is attenuated as evidenced by the downregulation of various pro-inflammatory genes.This sheds further light on the interplay of the various pathological processes taking place in primary lymphedema.
Subject(s)
Endothelial Cells/metabolism , Skin/cytology , Skin/metabolism , Adult , Aged , Cell Proliferation/drug effects , Cells, Cultured , Endothelial Cells/cytology , Endothelial Cells/pathology , Female , Gene Expression Profiling , Gene Expression Regulation , Humans , Lymphedema/congenital , Lymphedema/genetics , Lymphedema/metabolism , Lymphedema/pathology , Male , Middle Aged , Skin/pathology , Vascular Endothelial Growth Factors/pharmacologyABSTRACT
Lymphangiogenesis is an important process that contributes to the spread of cancer. Here we show that insulin-like growth factors 1 (IGF-1) and 2 (IGF-2) induce lymphangiogenesis in vivo. In a mouse cornea assay, IGF-1 and IGF-2 induce lymphangiogenesis as detected with LYVE-1, a specific marker for lymphatic endothelium. Interestingly, IGF-1-induced lymphangiogenesis could not be blocked by a soluble vascular endothelial growth factor receptor 3, suggesting that the vascular endothelial growth factor receptor 3-signaling pathway is not required for IGF-induced lymphangiogenesis. In vitro, IGF-1 and IGF-2 significantly stimulated proliferation and migration of primary lymphatic endothelial cells. IGF-1 and IGF-2 induced phosphorylation of intracellular signaling components, such as Akt, Src, and extracellular signal-regulated kinase in lymphatic endothelial cells. Immunohistochemistry, RT-PCR, and Affymetrix GeneChip microarray analysis showed that the receptors for IGFs are present in lymphatic endothelium. Together, our findings suggest that IGFs might act as direct lymphangiogenic factors, although any indirect roles in the induction of lymphangiogenesis cannot be excluded. Because members of the IGF ligand and receptor families are widely expressed in various types of solid tumors, our findings suggest that these factors are likely to contribute to lymphatic metastasis.
Subject(s)
Insulin-Like Growth Factor II/pharmacology , Insulin-Like Growth Factor I/pharmacology , Lymphangiogenesis/drug effects , Animals , Endothelium, Lymphatic/drug effects , Endothelium, Lymphatic/physiology , Female , Humans , Male , Mice , Mice, Inbred C57BL , Receptor, IGF Type 1/analysis , Receptor, IGF Type 2/analysis , Vascular Endothelial Growth Factor C/physiology , Vascular Endothelial Growth Factor D/physiology , Vascular Endothelial Growth Factor Receptor-3/physiologyABSTRACT
Cancer metastases are commonly found in the lymphatic system. Like tumor blood angiogenesis, stimulation of tumor lymphangiogenesis may require the interplay of several tumor-derived growth factors. Here we report that members of the PDGF family act as lymphangiogenic factors. In vitro, PDGF-BB stimulated MAP kinase activity and cell motility of isolated lymphatic endothelial cells. In vivo, PDGF-BB potently induced growth of lymphatic vessels. Expression of PDGF-BB in murine fibrosarcoma cells induced tumor lymphangiogenesis, leading to enhanced metastasis in lymph nodes. These data demonstrate that PDGF-BB is an important growth factor contributing to lymphatic metastasis. Thus, blockage of PDGF-induced lymphangiogenesis may provide a novel approach for prevention and treatment of lymphatic metastasis.