An in vitro and in vivo investigation of the cytotoxic effects of caffeic acid (3,4-dihydroxycinnamic acid) phenethyl ester and bortezomib in multiple myeloma cells.

BACKGROUND/AIM In this study, the in vitro and in vivo effectiveness of caffeic acid (3,4-dihydroxycinnamic acid) phenethyl ester (CAPE) in combination with bortezomib, a proteasome inhibitor, was explored in multiple myeloma (MM) cells. MATERIALS AND METHODS The cytotoxic effects of CAPE and bortezomib were determined by XTT cell proliferation assay. Apoptosis levels were analyzed with annexin V-fluorescein isothiocyanate, nuclear factor kappa beta (NF-κB) was analyzed with electrophoretic mobility-shift assay, and interleukin (IL)-6 levels were analyzed with enzyme-linked immunosorbent assay to evaluate CAPE's mechanism of action. To investigate the in vivo effectiveness of CAPE and bortezomib, an experimental plasmacytoma model was induced in BALB/c mice. RESULTS Increasing concentrations of CAPE and bortezomib decreased the proliferation of ARH-77 cells in a dose-dependent manner. With doses of CAPE IC50, a significant increase in apoptosis and a significant decrease in IL-6 levels were detected. The NF-κB DNA- binding activity decreased compared to the basal ARH-77 level. The administration of CAPE alone or in combination with bortezomib increased the rate of survival compared to the control group. CONCLUSION We think that our study, which is the first to demonstrate the in vitro and in vivo effectiveness of the.combined use of CAPE and bortezomib, will be a pioneer for future human applications of CAPE in MM.