Overexpression of
matriptase has been reported in a variety of human
cancers and is sufficient to trigger
tumor formation in mice, but the importance of
matriptase in
breast cancer remains unclear. We analysed
matriptase expression in 16 human
breast cancer cell lines and in 107 primary
breast tumors. The data revealed considerable diversity in the expression level of this
protein indicating that the significance of
matriptase may vary from case to case.
Matriptase protein expression was correlated with HER2 expression and highest expression was seen in HER2-positive cell lines, indicating a potential role in this subgroup. Stable overexpression of
matriptase in two
breast cancer cell lines had different consequences. In MDA-MB-231 human
breast carcinoma cells the only noted consequence of
matriptase overexpression was modestly impaired growth in vivo. In contrast, overexpression of
matriptase in 4T1 mouse
breast carcinoma cells resulted in visible changes in morphology, actin staining and cell to cell contacts. This correlated with downregulation of the cell-
cell adhesion molecule E-cadherin. These results suggest that the functions of
matriptase in
breast cancer are likely to be variable and cell context dependent.