Targeting the tumor initiating and differentiated populations within DU145 and PC3 carcinoma cell lines by CXCR4 antagonist and conventional therapy.

<p>(A) Treatment with CXCR4 antagonist AMD3100 decreases the CD133⁺/CD44⁺ population but did not significantly affect the CD133⁻/CD44⁻ population within prostate cancer cells. The use of cytotoxic drugs alone results in a decrease in proliferating tumor cells, but leads to an overall increase in the relative population of tumor initiating cells. Combinatorial treatment of PC3 cells with AMD3100 and the conventional chemotherapeutic drug 5-fluouracil decreases both undifferentiated and differentiated cells populations. PC3 cells were grown in serum-free, EBM medium with supplements and treated with the indicated concentrations of AMD3100 and 5-fluouracil. On the 5^th day the cells were subjected to flow cytometry analysis; *-p value<0.05. (B) Combinatorial therapy <i>in vivo</i> demonstrates significant inhibition of tumor growth compared to single drug treatment. The mice were treated with Taxotere (20 mg/kg, 1q.w., p.o) as described (19). Alzet pumps were used to deliver AMD3100 at a constant rate of 0.25 µg/kg/hour. The pumps loaded with AMD3100 or saline were implanted subcutaneously. The mice were observed for 8 weeks for appearance and development of tumors. (C) CD133 and CD44 immunostaining on frozen sections of xenograft tumors treated with combinatorial or mono-therapy from (B) revealed selective inhibition of the CD133⁺/CD44⁺ population by the CXCR4 antagonist AMD3100; *-p value<0.05. (D) Western blot analysis showed a significant decrease in FOXO3A phosphorylation in the tumors treated with AMD3100.