Tissue kallikrein and kinin receptor expression in an angiogenic co-culture neuroblastoma model

The sprouting of new blood vessels from pre-existing vasculature (angiogenesis) is essential for tumour survival, influenced by tumour cell-endothelial cell interactions and is tightly regulated by biochemical cues including the kallikrein-kinin system (KKS). We examined the structural interaction between neuroblastomas and endothelial cells (HUVECs) in 2-D and 3-D (matrigel) in vitro, co-culture models by light microscopy, and performed in situ mono- and co-labelling of various KKS proteins. Neuroblastomas formed footplate-like multiple contacts on angiogenic HUVECs without disrupting differentiation of HUVECs into cord-like structures. Tissue kallikrein and the kinin B1R and B2R receptors were demonstrated on interacting neuroblastomas and HUVECs to varying degrees, as well as at actual heterogeneous contact zones in both 2-D and 3-D models. This KKS immuno-reactivity was generally confined to peri-nuclear regions on HUVECs but concentrated on cell extensions on neuroblastomas. The KKS, known to enhance DNA synthesis and process pro-angiogenic precursors of both tumour cells and the extra-cellular matrix, may, by its multi-functional activities at sites of tumour-blood vessel interactions, regulate aspects of both angiogenesis and tumourigenesis.