Fig. 5.

CRBN expression correlated positively with the LD regimen; long-term exposure to lenalidomide induced multi-drug resistance.

(A) CRBN expression in JeKo-1 cells after treatment with 0.5 μM lenalidomide followed by 1-week removal of drug pressure; protein levels were normalized to β-actin. (B) Apoptosis and cell cycle status in lenalidomide-sensitive, -resistant, and -resensitized JeKo-1 cells after follow-up treatment with 1 μM lenalidomide. (C) Apoptosis and cell cycle status in lenalidomide-sensitive, -resistant, and -resensitized JeKo-1 cells after follow-up treatment with 20 μM dexamethasone. Data are the mean ± SD (**p < 0.01). (D) Apoptosis and cell cycle detection of JeKo-1 cells in the presence of ara-C (20 μM), CTX (50 μM), DDP (20 μM), MTX (10 μM), or THP (1 μM) in lenalidomide-sensitized, -resensitized, and -resistant JeKo-1 cells. Sensitized: No exposure to lenalidomide; resensitized: 1-week escape from lenalidomide; resistant: 2-week exposure to lenalidomide.