Optimization of an orthotopic murine model of head and neck squamous cell carcinoma in fully immunocompetent mice – Role of toll-like-receptor 4 expressed on host cells

For preclinical studies of immune-modulating anticancer drugs a murine model that attempts to parallel the clinical nature of head and neck cancer in fully immunocompetent mice is required. In this study we compared features of the squamous cell carcinoma (SCC) VII model after subcutaneous (back, flank) and orthotopic (floor of mouth) injection both in fully immunocompetent C3H/HeN and in previously studied C3H/HeJ mice, which harbor a functional toll-like receptor 4 (TLR-4) deficiency. As C3H/HeN mice do not harbor this deficiency, the presented murine model is an optimization of previously described C3H/HeJ models, which, because of the TLR-4-deficiency, have inherent drawbacks for tumor immunologic studies. We found that tumor growth was accelerated and tumor incidence was increased by about 20% after s.c. injection in TLR-4-deficient mice. Strikingly, tumor-related weight loss (cachexia) was more pronounced in fully immunocompetent C3H/HeN mice (26%) versus TLR-4-deficient C3H/HeJ mice (7.9% weight loss) at high tumor dose. Orthotopic tumors were biologically distinct from subcutaneous tumors as they showed accelerated growth and a distinct immune cell infiltrate. We conclude that a model of orthotopic implantation of SCC VII tumor cells into fully immunocompetent syngeneic C3H/HeN mice reflects features of human head and neck cancer and provides a valuable experimental model for immunological studies in this tumor entity. Our data suggest that TLR-4 expressed by host cells is involved in the regulation of tumor-related cachexia and tumor control.