Effect of the Connexin 43 Coupling to the Biobehavior of Multiple Myeloma Cells / 中国实验血液学杂志

ABSTRACT

OBJECTIVE@#To investigate the effect of gap junction intercellular communication (GJIC) combined by connexin43 (Cx43) and its signal to the biobehavior of multiple myeloma (MM) cells, and its possible mechanism.@*METHODS@#The mesenchymal stem cell (MSC) cells were isolated and cultured from patients with MM and normal donors. The expression of connexin43 (Cx43) in MSC cells from different sources was detected by RT-PCR and Western blot. The side population (SP) cells were sorted by flow cytometry (FCM). The effect of MSC cells from different sources to the cell cycle, Cx43 expression, colony formation in vitro, stem cell related genes expression, cytokines secretion and chemoresistance in MM SP cells as well as with or without Cx43 inhibitor 18α-glycyrrhetinic acid (18α-GA) was observed.@*RESULTS@#There was no significantly difference between the MSC isolated from normal donor and MM patients. Western blot showed that Cx43 expression in SP cells was up-regulated when the cells were incubated with MSC, and medium containing 18α-GA could partially inhibit it, moreover, it was more significant in MSC cells of MM patients. The ability of colony formation of SP cells in vitro was higher than those of MM cells and MM-MSC could promote the colony formation in a co-culture manner. The effect of MM-MSC to SP cells was down-regulated after 18α-GA was added. RT-PCR showed that there was several important stem cell-related genes including c-myc, Oct-4 Klf-4, and Sox-2 were found in RPMI 8226 cells, but those cells were up-regulated in SP cells (P0.05). Cytometry bead array assays showed that MM-MSCs could secrete high level of IL-6, but the levels of IL-6, IL-10 and TGF-β increased significantly when the MM-MSCs were co-cultured with SP cells (P<0.05), especially the levels of IL-6 and IL-10 were significantly higher than cultured alone. There was no significant change in the levels of bFGF and IL-17 before and after co-cultured. The levels of IL-6, IL-10 and TGF-β in supernatant decreased significantly after GJ inhibitor 18α-GA was added. PI/Annexin V assay showed that MM cells were sensitive to bortezomib (BTZ)-induced apoptosis, but the sensitivity for SP cells was weaker. The ratio of cell apoptosis was 75.2%±0.77% and 8.12%±0.86% (P<0.001), respectively. MM-MSC could down-regulate the cell apoptosis induced by BTZ, while the sensitivity of MM cells to BTZ could be partially recovered after GJ inhibitor was added.@*CONCLUSION@#MSC derived from MM patients can enhance GJIC to maintain its "hematopoiesis" by up-regulating the expression of Cx43 in MM cells, and at the same time promote cell proliferation and drug recistance by secreting multiple cytokines, which finally contributes to the relapse of MM.