The Metastatic Bone Marrow Niche in Neuroblastoma: Altered Phenotype and Function of Mesenchymal Stromal Cells

Abstract

Background: The bone marrow (BM) is the main site of metastases and relapse in patients with neuroblastoma (NB). BM-residing mesenchymal stromal cells (MSCs) were shown to promote tumor cell survival and chemoresistance. Here we characterize the MSC compartment of the metastatic NB BM niche. Methods: Fresh BM of 62 NB patients (all stages), and control fetal and adult BM were studied by flow cytometry using well-established MSC-markers (CD34−, CD45−, CD90+, CD105+), and CD146 and CD271 subtype-markers. FACS-sorted BM MSCs and tumor cells were validated by qPCR. Moreover, isolated MSCs were tested for multilineage differentiation and Colony-forming-unit-fibroblasts (CFU-Fs) capacity. Results: Metastatic BM contains a higher number of MSCs (p < 0.05) with increased differentiation capacity towards the osteoblast lineage. Diagnostic BM contains a MSC-subtype (CD146+CD271−), only detected in BM of patients with metastatic-NB, determined by flow cytometry. FACS-sorting clearly discriminated MSC(-subtypes) and NB fractions, validated by mRNA and DNA qPCR. Overall, the CD146+CD271− subtype decreased during therapy and was detected again in the majority of patients at relapse. Conclusions: We demonstrate that the neuroblastoma BM-MSC compartment is different in quantity and functionality and contains a metastatic-niche-specific MSC-subtype. Ultimately, the MSCs contribution to tumor progression could provide targets with potential for eradicating resistant metastatic disease.

Mesenchymal Stromal Cells in Neuroblastoma: Exploring Crosstalk and Therapeutic Implications

“…Furthermore, circulating melanoma cells have been described to interact with perivascular MSCs through CXCR4/CXCL12 signaling and melanoma cell adhesion molecule (MCAM, CD146) in vivo, an interaction shown to be required for BM invasion [ 112 ]. Interestingly, recent study from our group with primary patient samples has determined CD146 to be one of the surface molecules that identifies an MSC subtype, which is specifically present in the NB metastatic BM and might have tumor-related functions [ 113 ].…”

“…Yet, the interactions between NB cells and BM-MSCs are only starting to be investigated, with a few studies indicating a crosstalk of NB cells with BM-MSCs. Interestingly, our group recently demonstrated in primary NB patient samples that the number of MSCs is significantly increased in metastatic BM compared with NB-free BM, pointing toward a direct or indirect effect of NB cells on MSCs [ 113 ].…”

“…This enhanced the effects of BMP-4, which is—next to Wnt- and Notch signaling—part of one of three pathways that control osteoblastogenesis [ 164 ]. Importantly, recent study from our group with ex vivo analyses of NB patient-derived material demonstrated BM-MSCs from metastatic NB patients to be more prone to differentiate toward osteoblasts compared to MSCs from patients without BM metastases [ 113 ].…”

Artificial Tumor Microenvironments in Neuroblastoma

“…The ability of mesenchymal stromal cells to promote metastasis also adds another challenge to therapies. An increased number of mesenchymal stromal cells were seen in neuroblastoma bone marrow metastasis [ 37 ]. These mesenchymal stromal cells may promote metastasis to the bone marrow through their production of the chemoattractant, CXCL13 [ 38 ].…”

Aging of Bone Marrow Mesenchymal Stromal Cells: Hematopoiesis Disturbances and Potential Role in the Development of Hematologic Cancers

“…In breast cancer, MSC activity through CCL5 release and Tac1 upregulation markedly increased tumoral metastatic capacity [ 110 , 111 ]. In neuroblastoma, differences in both qualitative and quantitative features of MSCs affect tumoral progression in BM [ 112 ]. A MSC subpopulation expressing stemness, endothelial and pericytic cell markers seems to impair neoplastic cells homing to BM in breast and prostate cancer models [ 113 ].…”