Consistently, analyses of clinical breast cancer specimens revealed significantly increased PAK5 and USP4 levels and an association between higher PAK5 and USP4 expression and worse breast cancer patient survival.
Our findings demonstrated that circBMPR2 might function as a miR-553 sponge and then relieve the suppression of USP4 to inhibit the progression and tamoxifen resistance of breast cancer.
The migration and invasion assays showed that USP4 promotes human breast cancer cell migration and invasion by USP4 overexpression, and knockdown of USP4 by siRNA inhibits human breast cancer cell migration and invasion.
As a whole, our findings sugggest that USP4 acts as a tumor suppressor in breast cancer and that it may be an effective target for the treatment of breast cancer.
Importantly, AKT (also known as protein kinase B), which has been associated with poor prognosis in breast cancer, directly associates with and phosphorylates USP4.