Figure 4.

ATF3 functions as an oncogene or tumor suppressor in prostate cancer. ATF3 may be upregulated by androgen, thus induces cell proliferation and G1-to-S-phase transition of the cell cycle. In addition, ATF3 SUMOylation enhanced cyclin D1 (CCND1) activation, resulting in increased cell proliferation and colony formation. ATF3 was downregulated by Drg-1, a suppressor of metastasis. These implied that ATF3 serves an oncogene. ATF3 may act as a tumor suppressor by inhibiting androgen receptor, MMP2, AKT, causing inhibition of cell proliferation and invasion. Furthermore, upregulation of ATF3 by KLF6 leads to cell apoptosis. In sum, these findings demonstrate that dual roles of ATF3 as an oncogene or tumor suppressor is observed in prostate cancer.