C/EBPβ regulates sensitivity to bortezomib in prostate cancer cells by inducing REDD1 and autophagosome–lysosome fusion

•C/EBPβ stimulates prostate cancer cell autophagy by inducing autolysosome formation.•C/EBPβ also stimulates early autophagy by directly inducing REDD1.•Activation of autophagy in prostate cancer cells by bortezomib requires C/EBPβ.•C/EBPβ protects prostate cancer cells from bortezomib.•C/EBPβ knockdown reduces tumor growth and increases in vivo bortezomib sensitivity.