ABSTRACT
ADP-ribosylation factor 3 (ARF3) is a member of the KRAS proto-oncogene, GTPase(Ras) super-family of guanine nucleotide-binding proteins that mediates Golgi-related mitosis, but its role in malignant cells is unclear. In the present study, we found that mRNA and protein expression of ARF3 is up-regulated in breast cancer cells. Immunohistochemical analysis of 167 paraffin-embedded archived breast cancer tissues showed that ARF3 expression was localized primarily in the cytoplasm and was significantly up-regulated in malignant specimens compared to benign specimens. There were strong associations between ARF3 expression and clinicopathological characteristics in breast cancer. We also found that overexpressing ARF3 promoted, while silencing endogenous ARF3 inhibited, the proliferation of breast cancer cells by regulating cell cycle G1-S transition. Moreover, the pro-proliferative effect of ARF3 on breast cancer cells was associated with inactivation of the forkhead box O1 (FOXO1) transcription factor. ARF3 promotes breast cancer cell proliferation through the participation of FOXO1 and represents as a novel prognostic marker and therapeutic target for breast cancer.