Establishment of stable multiple myeloma cell line with overexpressed PDCD5 and its proapoptosis mechanism

The transfected multiple myeloma cell line showing a stable doxycycline (DOX)-induced expression of PDCD5 was established. PDCD5 overexpression in the transfected cell line was analyzed for its effect on the dexamethasone (DXM)-induced apoptosis along with a discussion on the mechanism.

(1) Lentiviral plasmid was used for the transfection of PDCD5 gene into the multiple myeloma cells. The screening was done by applying puromycin, and PDCD5 expression was induced by DOX. Real-time fluorescence quantitative PCR and Western Blot were performed to detect the expression levels of the target gene in the stable transfection group and the empty vector group; (2) The cell apoptosis rates of stable transfection group, blank group and empty vector group were measured by Annexin-APC/PI double staining flow cytometry; (3) Real-time fluorescence quantitative PCR and Western Blot were carried out to detect the expression levels of survivin, casepase-3 and Bcl-2 genes and proteins.

PDCD5 expression was significantly increased in the stably tranfected multiple myeloma cells compared with blank group and empty vector group. The cells in the transfection group were more sensitive to DXM, and the proportion of apoptotic cells was obviously higher than that of the blank group and the empty vector group (P<0.05). Survivin and Bcl-2 were considerably downregulated in U266/PDCD5 cells and combined DXM group than in the single agent group. However, caspase-3 was significantly upregulated.

Multiple myeloma cell line transfected with endogenous PDCD5 gene was established. The endogenous PDCD5 overexpression accelerated the cell apoptosis under DXM induction. The proapoptotic action of PDCD5 gene had the effect of activating casepase-3 and downregulating survivin and Bcl-2, which further promoted the apoptosis of multiple myeloma cells.