The Anti-Tumor and Bortezomib-Sensitizing Effects of Apigenin in Multiple Myeloma

Multiple myeloma (MM) is a kind of plasma cell neoplasm, accounting for approximately 10% of hematologic malignancies, with a high mortality rate. Apigenin (APG), a flavonoid, has been reported to have antiviral, antibacterial, antioxidant, and anticancer properties. However, the impact of APG on MM and bortezomib (BTZ) sensitization has not been investigated. The effects of APG on the proliferation, cell cycle, apoptosis, and oxidative stress of RPMI-8226 and U266 cells were investigated using CCK-8 assay, crystal violet staining, flow cytometry, Western blot, and PCR. It was observed that APG treatment increased the G1 phase cells, by which the expression of P21 increased, and the expression of CDK2 and Cyclin D1 decreased. Even though Necrostatin-1 (a potent necroptosis inhibitor) and Fer-1 (a ferroptosis inhibitor) could attenuate the effect of APG, the effect of Z-VAD-FMK (a pan-caspase inhibitor) was more significant. APG treatment increased the transcription of P53 and BAX, and the level of cleaved-PARP1 and cleaved-Caspase 3 in two MM cell strains. In addition, the APG application could dose-dependently increase the ROS, MDA, and GSSH levels, and decrease the GSH level in both cell strains, by which the transcription of GCLC, NQO1, GSTM2, NRF2, and GPX4 were attenuated. Finally, APG enhances the inhibitory effect of BTZ on MM cell growth. This study provides a potential therapeutic approach of APG on MM.