Role of intercellular junctions in the biological behavior of SP cells of multiple myeloma / 药学实践杂志

ABSTRACT

Objective To observe the effects of the intercellular gap junction (GJIC) composed of connexin 43(Cx43) in mesenchymal stem cells (MSCs) from different sources and their signals on the biological behavior of multiple myeloma (MM) lateral population cells (SP cells), and to explore its possible mechanism. Methods Mesenchymal stem cells (MSCs) from different sources were isolated and cultured. SP cells of MM cell line RPMI 8266 were sorted by flow cytometry. RT-PCR and Western blot were used to detect the expression of Cx43 gene and protein in MSCs, RPMI 8266 and SP cells from different sources. The effects of MSCs from different sources on SP cell cycle, Cx43 protein expression, colony formation ability in vitro, stem cell related gene expression, cytokine secretion and drug resistance were observed. Results There was no significant difference in morphology and phenotype between MM-MSCs and ND-MSCs. Both MM-MSCs and RPMI 8266 cells expressed a higher level of Cx43. Co-culture with MM-MSCs induced more SP cells to enter G0 phase (P<0.001). The expressions of c-myc, Kif4 and Sox2 genes in SP cells were significantly up-regulated, while the expression of Oct-4 gene was down-regulated. After adding α-GA, c-myc, Kif4 and Sox2 were down-regulated in varying degrees, but there was no significant difference. The expression of Cx43 was up-regulated by (31.00±2)% and (39.00±2)%, respectively. The colony formation ability in vitro was up-regulated, and the addition of α-GA could partially inhibit this effect. A small amount of c-myc, Kif4, Sox2 and Oct-4 genes were expressed in RPMI 8266. These genes were significantly up-regulated in SP cell subpopulation. MM-MSCs secreted high levels of interleukin (IL)-6. After co-culture with SP cells, the expressions of IL-6, IL-10 and TGF-β in the supernatant of MM-MSCs were up-regulated (P=0.0072, P=0.037). bFGF and IL-17 had no significant change. After adding α-GA, the levels of IL-6, IL-10 and TGF-β in the supernatant decreased. MM cells were sensitive to bortezomib (BTZ) induced apoptosis, but SP cells were less sensitive. Co-culture with MM-MSCs significantly reduced BTZ-mediated apoptosis. The addition of α-GA partially restored the sensitivity of MM cells to bortezomib. Conclusion MM-MSCs and multiple myeloma SP cells up-regulate the expression of Cx43 protein, form more GJIC, and promote the proliferation and drug resistance of SP cells by changing the cytokine secretion profile of MSCs, which may be one of the reasons for the recurrence of MM.