Localization of hRad9 in breast cancer

hRad9 is a cell cycle checkpoint gene that is up-regulated in breast cancer. We have previously shown that the mRNA up-regulation correlated with tumor size and local recurrence. Immunohistochemical studies were made to better define the role of hRad9 in breast carcinogenesis.

Localisation of hRad9 protein were performed on paired tumor and normal breast tissues. Immunoblotting with and without dephosphorylation was used to define the protein isolated from breast cancer cells.

Increased hRad9 protein was observed in breast cancer cells nucleus compared to non-tumor epithelium. This nuclear protein existed in hyperphosphorylated forms which may be those of the hRad9-hRad1-hHus1 complex.

Finding of hyperphosphorylated forms of hRad9 in the nucleus of cancer cells is in keeping with its function in ameliorating DNA instability, whereby it inadvertently assists tumor growth.