Hyaluronan promotes tumor lymphangiogenesis and intralymphantic tumor growth in xenografts

Hyaluxonan (HA), a high molecular weight glycosaminoglycan in the extracellular matrix, has been implicated in the promotion of malignant phenotypes, including tumor angiogenesis. However, little is known about the effect of HA on tumor-associated lymphangiogenesis. In this study, mouse hepatocellular carcinoma Hca-F cells combined with or without HA were injected subcutaneously into C3H/Hej mice, then angiogenesis and lymphangiogenesis of implanted tumors were examined by immunostaining for platelet-endothelial cell adhesion molecule-1 and lymphatic vascular endothelial hyaluronan receptor-1 respectively. Interestingly, we found HA promotes tumor lymphangiogenesis and the occurrence of intratumoral lymphatic vessels, but has little effect on tumor angiogenesis. Moreover, HA also promotes intralymphatic tumor growth, although it is not sufficient to potentiate lymphatic metastasis. These results suggest that HA, which is elevated in most malignant tumor stroma, may also play a role in tumor progression by promoting lymphangiogenesis.