Type IV collagen alpha6 chain-derived noncollagenous domain 1 (alpha6(IV)NC1) inhibits angiogenesis and tumor growth.

Type IV collagen is a major component of vascular basement membranes. The noncollagenous (NC1) domains of several alpha-chains of type IV collagen reveal a capacity to inhibit angiogenesis and tumor growth. Here, we demonstrate that the NC1 domain of the alpha6 chain of type IV collagen (alpha6NC1) is an endogenous inhibitor of angiogenesis and tumor growth. Recombinant alpha6NC1 inhibits human endothelial cell proliferation and neovascularization of Matrigel plugs in mice. The alpha6NC1 suppresses the growth of subcutaneously transplanted Lewis lung carcinoma and also spontaneous pancreatic insulinomas that develop in the Rip1Tag2 mice. Inhibition of tumor growth is associated with significantly diminished microvascular density. Collectively, our results demonstrate that alpha6NC1 is an endogenous inhibitor of angiogenesis and tumor growth.