Mechanism of mitochondrial protease LONP1 in the biological behavior of prostate cancer / 肿瘤

ABSTRACT

Objective:To explore the mechanism of Ion peptidase 1,mitochondrial(LONP1)in the progression of castration-resistant prostate cancer(CRPC). Methods:The expression levels of LONP1,N-Myc downstream-regulated gene 1(NDRG1)and androgen receptor(AR)proteins in benign prostatic hyperplasia cell line BPH-1,androgen-dependent human prostate cancer cell line LNCaP and castration-resistant prostate cancer(CRPC)cell line PC3 were examined by Western blotting.Recombinant vector carrying full-length LONP1 gene was delivered into LNCaP cells via lentiviral infection to establish stable LONP1-overexpressing(OE-LONP1)cell line,and LNCaP cells transfected with empty vector was used as the corresponding negative control(OE-NC).shRNA specifically targeting LONP1 gene(shLONP1)was delivered into PC3 cells to establish stable LONP1-silencing cell line,and PC3 cells transfected with empty shRNA vector(shNC)was used as the negative control.The effect of LONP1-overexpression and silencing on cell proliferation and invasion was analyzed by CCK-8 assay,colony formation assay and Transwell invasion assay in OE-LONP1 and shLONP1 cell lines.The effect of LONP1 on the AR/DNRG1 signaling axis was analyzed by co-immunoprecipitation assay and chromatin immunoprecipitation assay.The effect of NDRG1-silencing on the proliferation and invasion of shLONP1-expressing PC3 cells was evaluated by CCk-8 assay and Transwell assay.Tumor xenograft model was established by subcutaneously inoculating shLONP1-expressing PC3 cells and the negative control cells(PC3-shNC cells)into BALB/c nude mice.The mice were treated with DMSO or AR antagonist enzalutamide(ENZ).Then,the expression level of Ki-67 in tumor tissues was examined by immunohistochemical staining,and the cell apoptosis in tumor tissues was evaluated by TUNEL assay. Results:Compared with BPH-1 cells,LNCaP cells had lower(P＜0.05)while PC3 cells had higher(P＜0.05)expression level of LONP1 protein.The expression of AR and NDRG1 were inhibited in LNCaP cells when LONP1 was overexpressed(P＜0.05),whereas the expression of AR and NDRG1 were increased in PC3 cells when LONP1 was silenced(P＜0.05).The proliferation and invasion of LNCaP cells were promoted when LONP1 was overexpressed(P＜0.05),whereas the proliferation and invasion of PC3 cells were suppressed when LONP1 was knocked-down(P＜0.05).LONP1 can directly bind with AR to recognize the androgen response element(ARE)of NDRG1,which further inhibits the AR/NRDG1 signaling pathway to promote the progression of prostate cancer.The treatment of xenograft tumors in mouse models showed that both LONP1-silencing and ENZ application could inhibit tumor growth,and the best inhibitory effect was observed in mice treated with LONP1-silencing in combination with ENZ.The results of immunohistochemical staining and TUNEL assay indicated that the tumor tissues in the shLONP1+ENZ group had lower level of Ki-67 expression and higher level of cell apoptosis(P＜0.001). Conclusion:LONP1 is highly expressed in CRPC cell line PC3,and promotes prostate cancer progression by inhibiting AR/NDRG1 signaling transduction.