[Effect of silencing survivin gene on sensitivity of myeloma cells to adriamycin].

BACKGROUND & OBJECTIVE: Survivin, a member of the inhibitors of apoptosis protein family (IAPs), is overexpressed in many cancers, but not in normally differentiated adult tissues. It is known to be involved in poor prognosis and resistance to chemotherapy and radiotherapy in many cancers. This study was designed to use RNA interference technique to down-regulate the expression of survivin gene in human myeloma cell line KM3, observe its effects on apoptosis of KM3 cells and sensitivity of KM3 cells to adriamycin (ADM).

METHODS: Small interfering RNA (siRNA) targeting survivin mRNA was designed and in vitro chemosynthesized, and transfected into KM3 cells. Survivin mRNA and protein levels in KM3 cells were detected using reverse transcription-polymerase chain reaction (RT-PCR) and Western blot 24, 48, and 72 h after transfection. The apoptosis of KM3 cells was observed under fluorescent microscope before and after transfection. The sensitivity of KM3 cells to ADM before and after transfection was assessed.

RESULTS: The mRNA level of survivin was down-regulated by (47.0+/-4.3)%, (81.4+/-6.2)%, and (49.1+/-7.9)% of control at 24, 48, and 72 h after siRNA transfection, respectively; while the protein level of survivin was down-regulated by (39.6+/-3.8)%, (56.4+/-6.7)%, and (68.2+/-5.1)% of control, respectively. Under fluorescent microscope, the apoptosis rate of KM3 cells was (28+/-7)% at 48 h after transfection of survivin siRNA, which was significantly higher than that of control cells after transfection of negative siRNA (P<0.05). The 50% inhibition concentration (IC(50)) of ADM to KM3 cells was decreased from (1.12+/-0.14) micromol/L to (0.31+/-0.03) micromol/L.

CONCLUSION: Down-regulation of survivin expression in KM3 cells by siRNA could effectively induce apoptosis of KM3 cells and increase their sensitivity to ADM.