Figure 4. Anti-β₂M mAbs and BTZ combination treatment reduces BTZ-induced autophagy activation.

MM cells were cultured in medium with or without addition of BTZ (5 nM) or anti-β₂M mAbs (10 μg/mL), singly or in combination for 24 hours. Representative images of Western blot analysis (A) showing the levels of cleaved caspase 9 (c-cas9), caspase 3 (c-cas3), and PARP (c-PARP) in ARP-1 and MM.1S cells. Representative images of Western blot analysis showing the levels of the autophagy proteins LAMP-1, Beclin-1, and LC3B in (B) ARP-1 and MM.1S cells and (C) KAS-6.wt, KAS-6.BR, OPM-2.wt, and OPM-2.BR cells. (D) Annexin-V binding assay showing that rescuing Beclin 1 but not LC3B or LAMP-1 reduced apoptosis in ARP-1 cells treated with anti-β₂M mAbs alone or with mAbs plus BTZ. The experiments were carried out in triplicate. β-actin served as protein loading control. *P < 0.05, **P < 0.01.