[Correlation of Nucleostemin with Programmed Death-ligand-1 in Multiple Myeloma U266 Cells]

To investigate the correlation of nucleostemin (NS) gene with programmed death ligand-1 (PD-L1) in myeloma cells and the effect of NS expression down-regulation on the apoptosis of multiple myeloma cells, and to evaluate the associations among NS, PD-L1 and biological behavior of MM cells, and the feasibility of both NS and PD-1 as markers reflecting the status of MM cells.

The NS gene expression in U266 cells was down-regulated by NS-RNAi-GV248 recombinant lentivirus, the real-time PCR was used to detect the mRNA expression of NS, PD-L1 and PI3K/AKT/mTOR. The Western blot and flow cytometry were used to detect the expression of NS and PD-L1. The Annexin V-APC/7-AAD staining method was used to detect the apoptosis of U266 cells before and after knocking out the NS gene.

Under the condition of MOI=10, the transfection efficiency was more than 75% by means of the fluorescent microscopy; real-time PCR showed that compared with the negative control group (1.002±0.026), the mRNA expression of NS, PD-L1 and PI3K/AKT/mTOR gene in the transfection group (0.415±0.089) was significantly reduced (P＜0.05). The results of flow cytometry and Western blot showed that the protein expression of PD-L1 was significantly down-regulated after transfection. After down-regulation of NS gene expression, the apoptosis of U266 cells increased (P＜0.05).

The abnormal high expression of NS and PD-L1 genes exists in U266 cells, moreover, the down-regulation of PD-L1 and the related PISK/AKT/mTOR pathway gene expression appears after down-regulation of NS gene expression, which suggest that the cell biological changes resulted from above-mentioned results, show a synergestic effect on U266 cells.