Dexamethasone-resistant multiple myeloma cell line OPM1 treated with Dexamethasone and/or DAC

To identify genes responsible for the synergistic effect of DAC with Dex, we performed cDNA microarray analyses using cDNA prepared from Dex-resistant OPM1 cells treated with/without Dex, DAC or DAC+Dex. Cell lines were incubated for 72 h with/without 0.1 µM 5-aza-2'-deoxycytidine (DAC; Sigma), and were then incubated for 24 h with/without 1 µM Dexamethasone (EMD bioscience). The cells were then harvested, and total RNA was extracted for cDNA microarray analysis.