A Mechanism Study Of Bortezomib In Combination With Homoharringtonine Inhibit The Growth Of Multiple Myeloma Cells In The Bone Marrow Microenvironment

Objective:To investigate the mechanism of bortezomib in combination with homoharringtonine inhibit the growth of multiple myeloma cells in the bone marrow microenvironment in vitro.Methods:1. MM cell line U266 was co-cultured with human bone marrow stromal cell HS-5 to mimic the growth of MM cells in the bone marrow microenvironmen.2. U266 was incubated with interleukin 6 and the proliferation of cells was detected in the microenvironment.3.The drug sensitivity of BTZ or HHT to U266 cells was measured by CCK-8 kit to determine the best concentration or interval time.4. The cell cycle phase of U266 cells was determined by Flow cytometry.5.The expression level of KK alpha, IKK beta and I kappa B kinase in cytoplasm and P65, P50 or P52 in nucleus were measured by Western blot.Results:1. BTZ cuold inhibit the proliferation rate of U266 in a does-dependent manner.2. The propagation of U266 cells was inhibited by HHT in a does-dependent manner.3.The proliferation inhibition rate of U266 cells co-cultured with HS-5 to BTZ or HHT was decreased significantly compared with the U266 cells cultured single,(18.26±- 1.87%) vs(1.67 ±- 0.66%),(34.54±- 1.59%) vs( 0.53 ±- 0.19%).4. However,the combination of two drugs could increase the inhibition rate of U266 cells with HS-5.The inhibition rate could be 60.84±- 0.75%.The combination increased synergistic effect and specificity of the interval time of drugs.5.The combination of BTZ with HHT could influence the cell cycle phase of U266 cells.6.The combination of BTZ with HHT could inhibit the proliferation of U266 cells co-cultured with HS-5 by the NF-κB signaling pathway.6.1.The IκB kinase expression was down-regulated,leading to the high expression of NF-κB protein.6.2.The combination of BTZ with HHT could inhibit the proliferation of U266 cells co-cultured with HS-5 by changing the NF-κB classic and nonclassic activation pathway.7.BTZ with HHT had the remarkable proliferation inhibition effect of U266 cells co-cultured with IL- 6. As IL- 6 could significant effect on promoting proliferation of U266 cells, the proliferation inhibition rate of BTZ or HHT was decreased.But the combination was still able to inhibit U266 celsl proliferation.Conclusion:1.The combination of BTZ with HHT could inhibit the proliferation of the co-culture U266 cells. The combination increased synergitic effect and specificity of the interval time of drugs.2.The combination could decrease the proliferation inhibition of U266 cells co-cultured with IL-6.The combination was synergitic effect.3.The combination of BTZ with HHT could inhibit the proliferation of U266 cells co-cultured with HS-5 because of controlling the NF-κB classic and nonclassic activation pathway in part.