STL127705 synergize with olaparib in castration-resistant prostate cancer by inhibiting homologous recombination and non-homologous end-joining repair.

Therapeutic resistance to androgen-deprivation therapy is a major challenge for prostate cancer therapy. The present study aims to explore the effects of poly (ADP-ribose) polymerase (PARP) inhibitor olaparib and STL127705 on castration-resistant prostate cancer. Cell lines including PC-3 and enzalutamide-resistant LNCaP (erLNCaP) cells were treated with enzalutamide, enzalutamide plus olaparib, enzalutamide plus STL127705, or the combination of olaparib, STL127705, and enzalutamide. Cell viabilities and cell apoptosis were determined using the sulforhodamine B (SRB) assay and Annexin V/propidium iodide staining, respectively. Flow cytometry assay was applied to determine γH2AX intensity and the percentage of homologous recombination and non-homologous end-joining. Besides, a tumor-bearing animal model was established and treated with drugs as for cell lines. STL127705 and olaparib enhanced cytotoxicity of enzalutamide on erLNCaP and PC-3 cells. Furthermore, STL127705 and olaparib promoted enzalutamide-induced cell apoptosis and enhanced γH2AX intensity. study also showed that the combination of STL127705, olaparib, and enzalutamide inhibited homologous recombination and non-homologous end-joining repair systems in PC-3 cells. study demonstrated that the combination of STL127705, olaparib, and enzalutamide exhibited a significant anti-tumor effect. STL127705 combined with olaparib have a potential therapeutic effect on castration-resistant prostate cancer through inhibiting homologous recombination and non-homologous end-joining repair.