The GR-LEDGF/p75-HSP27 Axis Contributes to Cross-Resistance Between Enzalutamide and Docetaxel in Prostate Cancer

An emerging challenge in prostate cancer (PCa) treatment is the development of drug cross-resistance, wherein resistance to enzalutamide (ENZ), an androgen receptor signaling inhibitor (ARSI), also confers resistance to subsequent ARSI and docetaxel (DTX) treatments. The mechanisms underlying this drug cross-resistance remain unclear. Through RNA sequencing, we identified 93 overlapping differentially expressed genes (DEGs) in ENZ- and DTX-resistant PCa cells. Among the DEGs, <i>HSPB1</i>, which encodes heat shock protein 27 (HSP27), emerged as a key gene of interest. HSP27 is a known target of lens epithelium-derived growth factor p75 (LEDGF/p75), a transcription coactivator regulated by glucocorticoid receptor (GR). Both GR and LEDGF/p75 are overexpressed in advanced PCa and promote drug resistance. HSP27 was overexpressed in ENZ and DTX cross-resistant PCa cell lines and its expression was decreased upon GR or LEDGF/p75 silencing. ChIP sequencing confirmed GR binding at the <i>HSPB1</i> promoter. Pharmacological targeting of HSP27 in drug-resistant cells reduced proliferation, clonogenicity, and tumorsphere formation, and restored sensitivity to ENZ and DTX. Notably, high transcript expression of a GR-LEDGF/p75-HSP27 gene panel correlated with worse overall survival in PCa patients (n = 4259). These findings identified this axis as a driver of PCa drug cross-resistance and promising therapeutic target for overcoming treatment failure.