Objective: This study investigated the effects of combining inositol polyphosphate-4-phosphatase type II (INPP4B) gene transfection with poly(adenosine diphosphate-ribose) polymerase (PARP) inhibitor on castration therapy-resistant prostate cancer cell line, PC3.
Materials and methods: PC3 and LNcap cells were cultured in vitro, and the expression of INPP4B at the messenger RNA level was detected using reverse transcription polymerase chain reaction. PC3 cells transfected with recombinant lentivirus vector carrying the human INPP4B gene, and the expression of INPP4B was confirmed using real-time polymerase chain reaction and Western blot. The effect of INPP4B transfection or PARP inhibitor treatment or both on the proliferation, apoptosis and cell cycle, and level of protein kinase B (p-AKT) of PC3 cells was determined using Cell Counting Kit-8 assay, flow cytometry, and Western blot, respectively.
Results: INPP4B gene was lost in PC3 cells and successfully expressed in PC3 cells after recombinant lentivirus transfection. Cell proliferation was inhibited and the level of p-AKT decreased, causing a G1 arrest. PARP inhibitor had a remarkable negative effect on cell proliferation and promoted apoptosis, conferring a G2/M arrest, which was dose dependent; however, the level of intracellular p-AKT showed a slight rise. INPP4B gene transfection and PARP inhibitor combined blocked cell cycle progression in G1 phase, enhanced the inhibition of cell proliferation, and kept low intracellular p-AKT level.
Conclusions: Our results demonstrated that the combination of INPP4B gene transfection and PARP inhibitor had a synergistic antitumor effect on PC3 cells, which was expected to shed new light on combined biological therapy in castration therapy-resistant prostate cancer.
Keywords: Castration therapy–resistant prostate cancer; Combined; INPP4B; PARP inhibitor; PC3; PTEN.
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