Hedgehog pathway has been implicated tumorigenesis and progression in many tumor types including breast cancer in humans. However, association between canine mammary gland tumor and hedgehog signal has not been reported. We hypothesized that GLI-1 would be more expressed in dogs with mammary gland tumor than normal dogs. Mammary gland samples assessed for GLI1 expression using western blotting were collected from dogs that underwent surgery for therapeutic purposes, and from healthy laboratory beagle dogs as a normal control group. 63 female or spayed female dogs were selected for this study including 35 dogs with mammary tumors and 28 healthy controls. Serum GLI1 was measured using canine GLI1 Elisa kit. All dogs were recruited from VMTH at Seoul national university. Western blot results confirmed expression of GLI1 was higher in mammary tumor than normal mammary gland. Serum GLI-1 level was significantly higher in dogs with mammary tumor than in healthy dogs (medians of 26.05 and 17.03 ng/ml, respectively; p=0.002). Patients with malignant mammary neoplasms had significantly higher serum gli-1 concentrations than with benign mammary neoplasms (medians of 31.69 and 23.11 ng/ml, respectively, p=0.018). Aberrant hedgehog pathway expression might be related to canine mammary gland tumors. A limitation of this study is the relatively small sample size, 35 dogs with mammary gland tumor. Large sample size would allow for Multi-perspective analysis and analysis according to malignancy. Hedgehog pathway may represent a therapeutic target and validate potential for new biomarker in canine mammary gland tumor patients.
