Expression of ELOVL6 correlates with response to BTZ in MM patients and resistance to BTZ in cultured MM cells. (A) Expression of ELOVL6 in patient MM cells was determined using the GSE9782 data set between patients responsive (R) or nonresponsive (NR) to BTZ (R, n = 85; NR, n = 78) or dexamethasone (DEX) (R, n = 28; NR, n = 39). Probes for ELOVL6 were extracted based on the annotation from Affymetrix (shown above the plots). The 2-tailed Wilcoxon/Mann-Whitney test was used to determine statistical significance. P values between R and NR are shown above each therapy group. (B) Parental and BTZ-resistant MM cell lines with the following BTZ 50% inhibitory concentrations were used: MM.1S-P, 6 nM; MM.1S-R, 10 nM; RPMI8226-P, 3 nM; RPMI8226-R, 15 nM; KMS11-P, 6 nM; KMS11-R, 20 nM; ARH77-P, 8 nM; and ARH77-R, 25 nM. BTZ-resistant cells were collected 3 weeks after selection. Total cell extracts of logarithmically growing parental (P) and BTZ-resistant (R) cells were probed in immunoblotting with designated antibodies. ELOVL6-specific signals were normalized by glyceraldehyde-3-phosphate dehydrogenase (GAPDH)–specific signals and by ratio of these signals in corresponding parental cells. Shown immunoblots are representative images of at least 2 independent experiments. NS, nonsignificant.