Enhanced inhibition of tumor growth using TRAIL-overexpressing adipose-derived stem cells in combination with the chemotherapeutic agent CPT-11 in castration-resistant prostate cancer

BACKGROUND: This study investigated the inhibition of tumor growth in castrate-resistant prostate cancer (CRPC)-bearing mice by tumor necrosis factor–related apoptosis-inducing ligand (TRAIL)-overexpressing adipose-derived stem cells (ADSCs) (hTERT-ADSC.sTRAIL), which was enhanced by combined treatment with CPT-11. MATERIALS AND METHODS: An hTERT-ADSC.sTRAIL cell line was established by transfection with a lentiviral vector (CLV-Ubic) encoding the human sTRAIL gene. Quantitative polymerase chain reaction and Western blots were performed to confirm gene overexpression. An invasion study for the selective migration ability toward PC3 cells was performed. In the in vivo study, the tumor volume in mice treated with ADSC. sTRAIL and CPT-11 was measured. RESULTS: Carboxylesterase was generated from hTERT-ADSCs. The gene expression of sTRAIL from hTERT-ADSC.sTRAIL was shown. The directional migration of ADSC.sTRAIL cells toward PC3 cells was significantly stimulated by PC3 cells in vitro (P < 0.05). In the in vitro study, the viability of PC3 cells significantly decreased in the presence of ADSC.sTRAIL (62.7 ± 2.0%) and CPT-11 compared with that of CPT-11 alone (83.0 ± 1.0%) at a cell ratio as low as 0.05 (PC3: ADSC.sTRAIL) (P < 0.05). The proportion of apoptotic PC3 cells significantly increased in the presence of ADSC.sTRAIL (37.2 ± 2.1%) and CPT-11 compared with that of CPT-11 alone (16.5 ± 1.0%) (P < 0.05). In the in vivo study, the inhibition of tumor growth in CRPC-bearing mice by TRAIL-overexpressing adipose stem cells was enhanced by combined treatment with the chemotherapeutic agent CPT-11 compared with that in the treatment with cpt-11 alone. Immunohistochemical staining of the removed tumors showed anti-TRAIL–positive cells and apoptotic bodies after hTERT-ADSC.sTRAIL treatment or combined treatment with hTERT-ADSC.sTRAIL and CPT-11. CONCLUSIONS: Therapeutic stem cells expressing sTRAIL genes combined with CPT-11 can provide a new strategy for treating CRPC in clinical trials using the patients’ own ADSCs.