Adenovirus-delivered PDCD5 counteracts adriamycin resistance of osteosarcoma cells through enhancing apoptosis and inhibiting Pgp

In the present study, we investigated the roles of PDCD5 (programmed cell death 5) in multidrug re-sistance (MDR) of osteosarcoma cells and the possible lurking mechanisms. An adenovirus expression vector of PDCD5 was constructed and transfected into human adriamycin-resistant osteosarcoma cell line Saos-2/ADM. We found that up-regulation of PDCD5 could significantly enhance the sensitivity of Saos-2/ADM cells towards vincristine, methotrexate, cisplatin and arsenic trioxide (As2O3), and could decrease the capacity of cells to efflux adriamycin. PDCD5 could significantly down regulate the expression of P-glycoprotein (Pgp), but not affect the expression of multidrug resistance associated protein (MRP) or the glutathione S-transferase (GST). PDCD5 was also able to significantly increase the apoptotic activity of modified osteosarcoma cells. Further study of the biological functions of PDCD5 might be helpful in the understanding of the mechanisms of multidrug resistance (MDR) in osteosarcoma and exploring PDCD5 based adjuvant genetic therapy.