Lymphangiogenesis in tumor metastasis

Tumor metastasis is responsible for most of the deaths,and clinical analysis indicates that angiogenesis is critical for primary tumor growth.However,the initial route for tumor metastasis is predominantly through lymphangiogenesis instead of angiogenesis.Lymphangiogenesis is defined as the growth of new lymphatic capillary on the pre-existing lymphatic.The lymphatic microvessels are composed of a thin layer of endothelium poorly coated with pericytes/vascular smooth muscle cells,which is regarded as one of the most important pathways in tumor metastasis and dissemination.Therefore,spreading of tumor cells to lymph nodes through lymphangiogenesis is considered as one of the important prognostic indicators.Due to the lack of specific markers,lymphangiogenesis is a poorly studied area.Recent discovery of relatively specific markers for lymphatic endothelium,such as Prox-1,LYVE-1 and podoplanin,and successful isolation and culture of the lymphatic endothelial cells have significantly facilitated the researches in lymphangiogenesis and in the molecular pathways that regulate lymphangiogenesis.This review highlights the recent insights and developments in the field of lymphangiogenesis.