Regulation of docetaxel chemosensitivity by NR2F6 in breast cancer

Docetaxel (DTX)-based chemotherapy significantly eliminates rest cancerous cells and decreases the risk of death, thus remaining the mainstay of treatment for operable breast cancer (BCa). However, resistance or incomplete response to DTX occurs frequently, resulting in disease recurrence and poor prognosis. There is an urgent need to identify and understand the key factors and corresponding molecular bases driving this complicated pathogenesis. Herein, both data mining and profiling analysis using clinical BCa biopsies showed that expression levels of the nuclear receptor subfamily 2, group F, member 6 (NR2F6), a recently characterized central transcription factor for cancer immune surveillance, were significantly downregulated in DTX-resistant BCa. This downregulation, possibly regulated by leptin signaling, predicted a poor postoperative chemotherapy survival in DTX-resistant BCa. In both genetically engineered cell models and patient-derived xenograft models, we provided evidence that BCa cells with insufficient NR2F6 expression were less responsive to DTX treatment. Mechanistically, NR2F6 functioned as a potent corepressor of platelet-derived growth factor B receptor gene (PDGFRB) transcription by recruiting HDAC2 onto the PDGFRB promoter. Stable PDGFRB inhibition ameliorated NR2F6 deficiency-impaired response to DTX in BCa cells, indicating that NR2F6's effect on DTX response is mediated, at least in part, through transcriptional repression of PDGFRB. Collectively, our findings define NR2F6 as an negative regulator of cell survival and DTX resistance, probably by serving as a convergent point linking leptin signaling and PDGF-B/PDGFRβ axis, in BCa cells.