TGF-beta receptor I conditional knockout mice develop spontaneous squamous cell carcinoma.

We generated a mouse model with a conditional deletion of TGF-beta signaling in the neurons by crossing TGF-beta receptor I (TbetaRI) floxed mice with neurofilament-H (NF-H) Cre mice. 35% of F1 conditional knockout (COKO) mice developed spontaneous squamous cell carcinomas (SCCs) in periorbital and/or perianal regions. Transplantation of these tumors into athymic nude mice resulted in 62% tumorigenicity. To determine whether evasion of the immune response plays any role in this tumorigenesis, we analyzed the expression levels of receptors for interleukin-13 (mIL-13R), a key negative regulator of tumor immunosurveillance, and found that 33% of COKO tumors expressed the IL-13R alpha2 chain. Primary cultures of the SCCs expressing IL-13R alpha2 were sensitive to the cytotoxic effect of IL-13R-directed cytotoxin treatment. This is the first demonstration that loss of TbetaRI can lead to spontaneous tumor formation. These mice can serve as a unique mouse model of SCC to evaluate the tumorigenicity and effect of anti-cancer therapeutics.