Combination of phospholipase Cε knockdown with GANT61 sensitizes castrationresistant prostate cancer cells to enzalutamide by suppressing the androgen receptor signaling pathway

Castrationresistant prostate cancer (CRPC) is a major challenge in the treatment of prostate cancer (PCa). Phospholipase Cε (PLCε), an oncogene, has been found to be involved in the carcinogenesis, tumor proliferation and migration of several types of cancer. The effects, however, of PLCε on CRPC remains unclear. In the present study, the expression of PLCε and gliomaassociated homolog (Gli)1/Gli2 in benign prostatic hyperplasia (BPH), PCa and CRPC tissues and cells was investigated, and the correlations between PLCε and Gli1/Gli2 in CRPC tissues and cell lines were further explored. In addition, the effect of PLCε on cell proliferation and invasion was assessed in CRPC cell lines, and the sensitivity of ENR and 22RV1 cells to enzalutamide following the downregulation of PLCε expression was determined using lentivirusmediated shPLCε and/or treatment with specific Gli inhibitor GANT61. It was found that the PLCε expression was excessively upregulated in the majority of CRPC tissues, and PLCε positivity was linked to poor progressionfree survival (PFS) and overall survival (OS) in patients with PCa. Furthermore, PLCε knockdown significantly suppressed CRPC cell proliferation and invasion. Of note, it was found that PLCε knockdown increased the sensitivity of CRPC cells to enzalutamide in vitro by suppressing androgen receptor (AR) activities via the noncanonical Hedgehog/Gli2 and pSTAT3 signaling pathways. PLCε knockdown was shown to increase the sensitivity of CRPC cell xenografts to enzalutamide in vivo. Finally, the combination of PLCε knockdown with GANT61 significantly sensitized CRPC cells to enzalutamide. Collectively, the results of the present study suggest that PLCε is a potential therapeutic target for CRPC.