Establishment of four pairs of canine mammary tumour cell lines derived from primary and metastatic origin and their E‐cadherin expression

Four new pairs of canine mammary carcinoma cell lines derived from both primary and metastatic lesions were established. The cells were cultured in RPMI-1640 with 10% fetal bovine serum and they showed stable growth for more than 120 passages. Using these cell lines, the expression of E-cadherin was measured by flow cytometry and the function of E-cadherin was evaluated by cell aggregation assay and results from the primary and metastatic lesions were compared statistically. E-cadherin was strongly expressed in all of the cell lines, without a notable difference between cells of primary and metastatic origin. In the cell aggregation assay, the function of E-cadherin was significantly weaker in the cells of primary origin (p < 0.05), as compared with cells of metastatic origin. The present results suggest that a reduction in E-cadherin function may be implicated in the invasive and metastatic potential of canine mammary tumour cells; however, further study will be needed to clarify E-cadherin function in the context of the metastasis of canine mammary carcinoma.