Communication between bone marrow mesenchymal stem cells and multiple myeloma cells: Impact on disease progression

Table 1 Summary for the key soluble factors involved in multiple myeloma/bone marrow mesenchymal stem cells communication

Soluble factors	Origin	Function	Ref.
SDF1α	BMSCs	Chemoattractant of MM cell towards the BM microenvironment	[38]
IL-1β	MM cells	Act over BMSCs inducing the secretion of soluble factors, mainlyIL-6	[45]
IL-6	BMSCs	Closely related with cancer pathogenicity due to it proto-oncogenic and anti-apoptotic effect over MM cells	[46,47]
		Immunosuppressive effect over T cells
		Also related with bone destruction by inducing the expression of RANKL by the MM cells
VEGF	BM cells, MM cells	Promotes bone neovascularization, essential for tumour progression	[58]
RANKL	MM cells	Induce the commitment of the macrophage/monocyte precursor cells to the osteoclast lineage. Promoting indirectly bone destruction	[63]
DKK-1	MM cells	Disruptor of bone homeostasis by inhibiting BMSCs differentiation into osteoblasts	[66,67]

SDF1α: Stromal cell derived factor 1α; BM-MSC: Bone marrow mesenchymal stem cells; MM: Multiple myeloma; IL: Interleukin; RANKL: Receptor activator of NFκΒ ligand; VEGF: Vascular endothelial growth factor; DKK-1: Dickkopf-1.