Nitrogen permease regulator like-2 regulates sensitivity of castration-resistant prostate cancer to olaparib

Abstract

Objective To investigate the effect of nitrogen permease regulator like-2 (NPRL2) on the sensitivity of castration-resistant prostate cancer (CRPC) to olaparib. Methods Immunohistochemical staining of NPRL2 was performed in surgical specimens from the patients with benign prostatic hyperplasia (BPH), common prostate cancer (PCa) and CRPC. The expression of NPRL2 in the above tissues was observed and compared. Western blot assay was used to detect the protein level of NPRL2 in normal prostate epithelial cell line RWPE-1, prostate cancer cell line LNCaP and enzaliline-resistant castrated prostate cancer cell line LNPER. Overexpression and interference of NPRL2 were established by transfection of lentivirus into CRPC cells. The overexpression and interference efficiencies of NPRL2 were verified by real-time fluorescent PCR and Western blotting. ATM protein expression was detected by Western blotting. Cell proliferation and cytotoxicity were detected by CCK-8 assay, cell apoptosis was detected by flow cytometry, and invasion and migration were used with Transwell chamber test. Results Immunohistochemical assay showed that NPRL2 was highly expressed in the CRPC tissues. Western blotting showed that NPRL2 was down-regulated in RWPE-1 cells but highly expressed in LNCaP and LNPER cells. After successfully constructed a stable strain that overexpressed and interfered with NPRL2, qPCR and Western blotting showed that lentiviral transfection significantly increased and decreased the expression of NPRL2 at mRNA and protein levels, respectively(P < 0.01). And the results of CCK8 assay, flow cytometry and Transwell test indicated that silencing NPRL2 combined with olaparib treatment significantly inhibited cell growth, prevented cell invasion and metastasis, and promoted cell apoptosis when compared with the negative control group (P < 0.01). NPRL2 was positively correlated with ATM expression, and NPRL2 overexpression combined with olaparib treatment significantly enhanced ATM expression. Conclusion NPRL2 interference increases the sensitivity of CRPC cells to olaparib.

Keywords

• castration resistant prostate cancer
• nitrogen permease regulator like-2
• olaparib
• sensitivity