BTF3 confers oncogenic activity in prostate cancer through transcriptional upregulation of Replication Factor C

High levels of Basic Transcription Factor 3 (BTF3) have been associated with prostate cancer. However, the mechanisms underlying the role of BTF3 as an oncogenic transcription factor in prostate tumorigenesis have not been explored. Herein, we report that BTF3 confers oncogenic activity in prostate cancer cells. Mechanistically, while both BTF3 splicing isoforms (BTF3a and BTF3b) promote cell growth, BTF3b, but not BTF3a, regulates the transcriptional expression of the genes encoding the subunits of Replication Factor C (RFC) family that is involved in DNA replication and damage repair processes. BTF3 knockdown results in decreased expression of RFC genes, and consequently attenuated DNA replication, deficient DNA damage repair, and increased G2/M arrest. Furthermore, knockdown of the RFC3 subunit diminishes the growth advantage and DNA damage repair capability conferred by ectopic overexpression of BTF3b. Importantly, we show that enforced BTF3 overexpression in prostate cancer cells induces substantial accumulation of cisplatin-DNA adducts and render the cells more sensitive to cisplatin treatment both in vitro and in vivo. These findings provide novel insights into the role of BTF3 as an oncogenic transcription factor in prostate cancer and suggest that BTF3 expression levels may serve as a potential biomarker to predict cisplatin treatment response.