Proposed model of hCAP18/LL-37 up regulation as mediated by tumor-macrophage interactions.

<p>In tumor microenvironment, macrophages are activated by versican V1 produced by cancer cells, which then leads to activation of TLR2/6 and subsequent induction of Cyp27B1. As a consequence 25D3 is converted to 1,25D3, which then activates VDR, resulting in increased macrophage hCAP18/LL-37 expression. The released LL-37 initiates a tumor-promoting effect and increases tumor proliferation and invasion.