Baicalein Synergy Lenalidomide To Induce Apoptosis Of Myeloma Cell

To understand the apoptotic effects and cereblon (CRBN) gene and protein expression induced by baicalein in MM cells.

Apoptotic MM cells induced baicalein，lenalidomide or combination of BAI and lenalidomide were stained by using Annexin-V and analyzed by flow cytometry. RT-PCR was used to detect CRBN gene expression in MM cells. CRBN protein expression was detected by western blot in MM cell lines.

At the concentration of 40 μmol/L, baicalein can induce apoptosis of U266 cells in a time-dependent manner. At the different BAI treated time points (24h, 48h, 72h), the apoptotic cell percentages were 6.11%, 11.9%, 16.7%; After treated RPMI 8226 cells for 72 hours, combined application of baicalein and lenalidomide (both concentrations are 40 μmol/L) could induce more cell apoptosis than baicalein or lenalidomide alone. The apoptotic cell percentages induced by baicalein, lenalidomide or combined application of baicalein and lenalidomide were 15.9%, 4.27%, and 57.5%. CRBN gene expression detected by RT-PCR could be induced by baicalein in U266 cells in a dose-and time-dependent manner. Treated U266 cells for 24h at concentrations of 10 μmol/L, 20 μmol/L and 40 μmol/L, baicalein upregulated CRBN gene expression times were 2.246 ± 0.068, 2.399 ± 0.178 and 3.591 ± 0.061,respectively，compared to the control group. Statistically, the P values were 0.003, 0.009 and 0.001; Treated U266 cells at concentrations of 40 μmol/L at different time points (6h, 12h and 24h), baicalein upregulated CRBN gene expression times were 2.372 ± 0.079, 2.494 ± 0.189 and 3.228 ± 0.151, its P values were 0.002, 0.008 and 0.002.CRBN protein expression detected by using western blot could be induced by baicalein in both U266 and RPMI8226 cell lines.

Baicalein at suitable concentrations induced MM cells apoptosis in a time-dependent manner. Comparison with the single component used alone,combined application of baicalein and lenalidomide exhibited stronger inhibition effect on proliferation of RPMI 8226. Considering CRBN is the cellular target for lenalidomide, baicalein can up-regulate the CRBN gene and protein expression in MM cells and may enhance MM cell sensitivity to apoptotic stimuli. Therefore, baicalein up-regulated CRBN gene and protein expression and sensitized MM cells to apoptosis stimuli induced by lenalidomide. It provides us a possibility for baicalein clinical application to overcome the resistance to lenalidomide for MM patients in the future

No relevant conflicts of interest to declare.