Neuroblastoma and bone metastases: clinical significance and prognostic value of Dickkopf 1 plasma levels

Neural crest cells development and neuroblastoma progression: Role of Wnt signaling

Neuroblastoma (NB) is one of the most common heterogeneous extracranial cancers in infancy that arises from neural crest (NC) cells of the sympathetic nervous system. The Wnt signaling pathway, both canonical and noncanonical pathway, is a highly conserved signaling pathway that regulates the development and differentiation of the NC cells during embryogenesis. Reports suggest that aberrant activation of Wnt ligands/receptors in Wnt signaling pathways promote progression and relapse of NB. Wnt signaling pathways regulate NC induction and migration in a similar manner; it regulates proliferation and metastasis of NB. Inhibiting the Wnt signaling pathway or its ligands/receptors induces apoptosis and abrogates proliferation and tumorigenicity in all major types of NB cells. Here, we comprehensively discuss the Wnt signaling pathway and its mechanisms in regulating the development of NC and NB pathogenesis. This review highlights the implications of aberrant Wnt signaling in the context of etiology, progression, and relapse of NB. We have also described emerging strategies for Wnt-based therapies against the progression of NB that will provide new insights into the development of Wnt-based therapeutic strategies for NB.

Different tumorigenicity and distinct metastasis and gene signature between orthotopic and subcutaneous neuroblastoma xenografted mice

Patient-derived (PDX) and cell-derived (CDX) xenograft models are widely used in preclinical studies of human neuroblastoma. In this study, we constructed orthotopic and subcutaneous neuroblastoma CDX models by injecting human neuroblastoma cells into the adrenal gland and the flanks of immunodeficient mice, respectively. The tumorigenesis, metastasis and response to chemotherapy for the two models were also compared. Our results indicated that orthotopic tumor mice showed significantly faster tumor growth than that of subcutaneous mice. Importantly, the expression of PHOX2B and GAB2 was dramatically increased in the tumors of orthotopic CDX mice. Furthermore, orthotopic CDX mice developed multiple organ metastasis resembling that of neuroblastoma patients, while metastasis occurred predominantly in lung in subcutaneous CDX mice. Moreover, the two CDX models showed comparable response to cyclophosphamide treatment. Our results suggest that orthotopic CDX mice are superior to subcutaneous CDX mice as a preclinical model to study human neuroblastoma.

Dickkopf Proteins and Their Role in Cancer: A Family of Wnt Antagonists with a Dual Role

The Wnt signaling pathway regulates crucial aspects such as cell fate determination, cell polarity and organogenesis during embryonic development. Wnt pathway deregulation is a hallmark of several cancers such as lung, gastric and liver cancer, and has been reported to be altered in others. Despite the general agreement reached by the scientific community on the oncogenic potential of the central components of the pathway, the role of the antagonist proteins remains less clear. Deregulation of the pathway may be caused by overexpression or downregulation of a wide range of antagonist proteins. Although there is growing information related to function and regulation of Dickkopf (DKK) proteins, their pharmacological potential as cancer therapeutics still has not been fully developed. This review provides an update on the role of DKK proteins in cancer and possible potential as therapeutic targets for the treatment of cancer; available compounds in pre-clinical or clinical trials are also reviewed.

Bone Marrow Environment in Metastatic Neuroblastoma

The study of the interactions occurring in the BM environment has been facilitated by the peculiar nature of metastatic NB. In fact: (i) metastases are present at diagnosis; (ii) metastases are confined in a very specific tissue, the BM, suggestive of a strong attraction and possibility of survival; (iii) differently from adult cancers, NB metastases are available because the diagnostic procedures require morphological examination of BM; (iv) NB metastatic cells express surface antigens that allow enrichment of NB metastatic cells by immune-magnetic separation; and (v) patients with localized disease represent an internal control to discriminate specific alterations occurring in the metastatic niche from generic alterations determined by the neoplastic growth at the primary site. Here, we first review the information regarding the features of BM-infiltrating NB cells. Then, we focus on the alterations found in the BM of children with metastatic NB as compared to healthy children and children with localized NB. Specifically, information regarding all the BM cell populations and their sub-sets will be first examined in the context of BM microenvironment in metastatic NB. In the last part, the information regarding the soluble factors will be presented.

A 3D printed in vitro bone model for the assessment of molecular and cellular cues in metastatic neuroblastoma

Metastasis is a complex and multifactorial process highly dependent on the interaction between disseminated tumor cells and the pre-metastatic niche. The metastatic sites detected in the bone of patients affected by neuroblastoma (NB), a malignancy of the developing sympathetic nervous system, are particularly aggressive. To improve our current knowledge of metastatic tumor cell biology and improve treatment success, appropriate in vitro and in vivo models that more closely resemble the native metastatic niche are needed. In this study, the impact of the geometry of synthetic β-tricalcium-phosphate (β-TCP) structures on the interaction of NB tumor cells with the stromal component has been examined. The tumor microenvironment is dynamically shaped by the stroma, which sustains the growth of NB cells inside the metastatic niche. The 3D growth conditions are a determining factor for the cell proliferation rate in β-TCP. With respect to planar counterparts, channeled 3D β-TCP structures stimulate more interleukin-6 and Fibronectin production and define Connexin 43 distribution inside the cells. Together, these results highlight how the biomechanical properties of the 3D microenvironment enable tumor cells to form spheroid-shaped arrangements. This, in turn, facilitates their pro-migratory and pro-invasive patterns and mimics the in vivo situation by translating realistic mechanobiological cues to the metastatic NB.

Serum-derived exosomes from neurofibromatosis type 1 congenital tibial pseudarthrosis impaired bone by promoting osteoclastogenesis and inhibiting osteogenesis

Treatment of congenital pseudarthrosis of the tibia (CPT) still is full of challenges in pediatric orthopedist. Serum-derived exosomes (SDEs) have been proven to be participated in bone remodeling. However, the molecular changes in SDEs of CPT children and their pathologies have not been elucidated. In this study, SDEs were isolated and purified from CPT patients (CPT-SDEs) associated with neurofibromatosis type 1 (NF1) and normal children (Norm-SDEs). Then we obtained the proteomics profile of SDEs by combining liquid chromatography-tandem mass spectrometry (LC-MS/MS) and tandem mass tag label-based quantitation. In vitro, the efficacy of SDEs on osteoblastic differentiation of MC3T3-E1 cells and osteoclastogenesis ability of RAW264.7 cells were evaluated by quantitative real-time PCR (qRT-PCR) and cytochemical staining. In vivo, we used micro-CT to assess cortical bone mass and trabecular microstructures to reflect the influence of SDEs on bone remodeling after injection into the tail vein of rats. Based on proteomics analysis, 410 differentially expressed proteins, including 289 downregulated proteins and 121 upregulated proteins, were identified in the CPT-SDEs. These proteins have multiple biological functions associated with cellular metabolic processes, catalytic activity, and protein binding, which are important for cell differentiation and proliferation. In vitro, CPT-SDEs decreased the osteogenic differentiation of MC3T3-E1 cells and promoted the osteoclastogenesis of RAW264.7 cells. Injection of CPT-SDEs into the tail vein for two months resulted in bone loss in rats, as indicated by the decrease in trabecular and cortical bone mass. Our findings demonstrated the differences in proteins in SDEs between normal and CPT children with NF1. These differentially expressed proteins in CPT-SDEs contributed to deteriorating trabecular bone microstructures by inhibiting bone formation and stimulating bone resorption.

LncRNA XIST facilitates cell growth, migration and invasion via modulating H3 histone methylation of DKK1 in neuroblastoma

Long non-coding RNAs (lncRNAs) have been confirmed to be aberrantly expressed and involved in the progression of neuroblastoma. This study aimed to explore the expression profile of lncRNA X-inactive specific transcript (XIST) and its functional involvement in neuroblastoma. In this study, the relative level of XIST in neuroblastoma tissues and cell lines was detected by qPCR, and DKK1 protein expression was determined using western blot. The effect of XIST on cell growth, invasion and migration in vitro and in tumorigenesis of neuroblastoma was assessed. The level of H3K27me3 in DKK1 promoter was analyzed with ChIP-qPCR. Interaction between XIST and EZH2 was verified by RNA immunoprecipitation (RIP) and RNA pull-down assay. XIST was significantly upregulated in neuroblastoma tissues (n = 30) and cells lines, and it was statistically associated with the age and International Neuroblastoma Staging System (INSS) staging in neuroblastoma patients. Downregulation of XIST suppressed the growth, migration and invasion of neuroblastoma cells. EZH2 inhibited DKK1 expression through inducing H3 histone methylation in its promoter. XIST increased the level of H3K27me3 in DKK1 promoter via interacting with EZH2. Downregulation of XIST increased DKK1 expression to suppress neuroblastoma cell growth, invasion, and migration, which markedly restrained the tumor progression. In conclusion, XIST downregulated DKK1 by inducing H3 histone methylation via EZH2, thereby facilitating the growth, migration and invasion of neuroblastoma cells and retarding tumor progression.

Calcium phosphate scaffolds with defined interconnecting channel structure provide a mimetic 3D niche for bone marrow metastasized tumor cell growth

Metastasis of tumor cells in the bone marrow (BM) is a multi-step and highly dynamic process during which cells succumb important phenotypic changes. Behavior of disseminated tumor cells in BM is strictly regulated by three-dimensional (3D) cell-cell and cell-matrix interactions. In this study, we explored whether the β-tricalcium-phosphate (β-TCP) scaffolds with a tailored interconnecting channel structure could enable appropriate 3D mimetic BM microenvironment for the growth of metastatic neuroblastoma cells. The scaffolds provided the mechanical support for human mesenchymal stromal cells (hMSC) allowing them to proliferate, differentiate towards osteoblasts, and produce the deposits of extracellular matrix inside the interconnected channels. The in vitro microenvironment shaped by stromal cells was then tailored by neuroblastoma tumor cells. Immunohistological analyses confirmed the organization of tumor cells into the forms of spheres only when co-cultured with hMSC-derived osteoblasts. The growing rate of tumor cells in 3D conditions was less marked comparing to the one of the cells grown as 2D monolayer as confirmed by decreased Ki-67 expression. Instead, the 3D culturing of neuroblastoma cells inside supportive stroma promoted cell quiescence as sustained by increased p27 level. A balance between cell proliferation, survival, and differentiation was more evident for tumor cells grown inside the 3D scaffolds, thus mirroring better the situation that occurs in vivo where the cells do not follow the exponential growth rate. We conclude that the proposed 3D β-TCP scaffold type provides a mimetic 3D in vitro niche suitable for studying behavior of BM metastasized tumor cells. STATEMENT OF SIGNIFICANCE: Bone marrow (BM) niche is a favorite target of metastatic neuroblastoma cells. To better address the molecular mechanisms that sustain spatiotemporal organization of neuroblastoma cells in the marrow we mimicked the three-dimensional (3D) assembly of stromal and tumor cells inside β-tricalcium-phosphate (β-TCP) scaffolds. β-TCP scaffolds with a tailored interconnecting channel structure provided mechanical support to mesenchymal stromal cells allowing them to differentiate towards osteoblasts and to produce extracellular matrix. A dynamic cell-matrix interplay favored the characteristic rosette-like growth of metastatic neuroblastoma cells and triggered their quiescence. With our study, we confirmed the potential of β-TCP scaffolds with reproduced BM niche as a cost-effective in vitro model for the growth of disseminated tumor cells, and for related biological and pharmacological surveys.

Production and Characterization of Monoclonal and Polyclonal Antibodies Against Truncated Recombinant Dickkopf-1 as a Candidate Biomarker

Several studies have reported an increased serum level of Dickkopf (DKK-1) protein in a variety of cancers, including multiple myeloma, lung, colorectal, bone loss, and Alzheimer's disease. This protein has potential to be used as a biomarker for the diagnosis of some cancers, especially bone loss in multiple myeloma. In the present study, to measure the concentration level of DKK-1 protein, rabbit polyclonal antibody (pAb) and mouse monoclonal antibodies (mAbs) were produced against this protein. New Zealand white rabbits and BALB/c mice were immunized with the chimeric recombinant DKK-1 antigen. Immunized mouse spleen cells were fused with SP2/0 cells to generate anti-rDKK-1 antibody-producing hybridoma cells. Antibodies were purified by protein A affinity chromatography and assessed using sodium dodecyl sulfate polyacrylamide gel, western blotting and enzyme-linked immunosorbent assay. These results implied that the pAb and mAb were produced against the DKK-1 protein. The Kd value of 5 × 10^-9 M was recorded for the mAb MR6F3 toward native DKK-1, and the Ig isotype was identified as IgG2b. No cross-reactivity was shown with DKK-2 by MR6F3. Collectively, our results revealed that the produced pAb and mAb could be used in the measurement of DKK-1 protein.

Wnt signaling in bone metastasis: mechanisms and therapeutic opportunities

Bone metastasis frequently occurs in advanced cancer patients, who will develop osteogenic/osteolytic bone lesions in the late stage of the disease. Wnt signaling pathway, which is mainly grouped into the β-catenin dependent pathway and β-catenin independent pathway, is a well-organized cascade that has been reported to play important roles in a variety of physiological and pathological conditions, including bone metastasis. Regulation of Wnt signaling in bone metastasis involves multiple stages, including dissemination of primary tumor cells to bone, dormancy and outgrowth of metastatic tumor cells, and tumor-induced osteogenic and osteolytic bone destruction, suggesting the importance of Wnt signaling in bone metastasis pathology. In this review, we will introduce the involvement of Wnt signaling components in specific bone metastasis stages and summarize the promising Wnt modulators that have shown potential as bone metastasis therapeutics, in the hope to maximize the therapeutic opportunities of Wnt signaling for bone metastasis.

Bone turnover markers and novel biomarkers in lung cancer bone metastases

CONTEXT

Lung cancer still remains the leading cause of cancer-related mortality worldwide. Bone is one of preferred metastatic sites for lung cancer cells. So far, both accurate diagnosis and effective treatment of lung cancer bone metastases are difficult.

OBJECTIVE

This review aimed to evaluate roles of bone turnover markers (BTMs), microRNAs (miRNAs), dickkopf1 (DKK1) and insulin like growth factor binding protein 3 (IGFBP-3) in lung cancer bone metastases.

METHODS

We searched articles about these four biomarkers in lung cancer bone metastases mainly in PubMed.

RESULT

The levels of bone specific alkaline phosphatase (BALP), cross-linked carboxy-terminal telopeptide of type-I collagen (ICTP) and N-terminal telopeptides of type-I collagen (NTX) were reported to be significantly increased in lung cancer patients with bone metastases. ALP, NTX and bone sialoprotein were thought to be associated with prognosis of lung cancer patients with bone metastases. MiRNA-335, miRNA-33a, miRNA-21, DKK1 and IGFBP-3 were revealed to be novel biomarkers in lung cancer bone metastases.

DISCUSSION AND CONCLUSION

Current researches have revealed that BTMs, miRNAs, DKK1 and IGFBP-3 may be useful in diagnosis, prognosis evaluation or treatment of lung cancer bone metastases. More studies about these biomarkers in lung cancer bone metastases are needed.

WNT signaling, the development of the sympathoadrenal-paraganglionic system and neuroblastoma

Neuroblastoma (NB) is a tumor of the sympathoadrenal system arising in children under 15 years of age. In Germany, NB accounts for 7% of childhood cancer cases, but 11% of cancer deaths. It originates from highly migratory progenitor cells that leave the dorsal neural tube and contribute neurons and glial cells to sympathetic ganglia, and chromaffin and supportive cells to the adrenal medulla and paraganglia. Clinically, histologically and molecularly, NBs present as extremely heterogeneous, ranging from very good to very poor prognosis. The etiology of NB still remains unclear and needs to be elucidated, however, aberrant auto- and paracrine embryonic cell communications seem to be likely candidates to initiate or facilitate the emergence, progression and regression of NB. The wingless-type MMTV integration site (WNT) family of proteins represents an evolutionary highly conserved signaling system that orchestrates embryogenesis. At least 19 ligands in the human, numerous receptors and co-receptors are known, which control not only proliferation, but also cell polarity, migration and differentiation. Here we seek to interconnect aspects of WNT signaling with sympathoadrenal and paraganglionic development to define new WNT signaling cues in the etiology and progression of NB.

Mesenchymal stromal cell secretome up-regulates 47 kDa CXCR4 expression, and induce invasiveness in neuroblastoma cell lines

Neuroblastoma accounts for 15% of childhood cancer deaths and presents with metastatic disease of the bone and the bone marrow at diagnosis in 70% of the cases. Previous studies have shown that the Mesenchymal Stromal Cell (MSC) secretome, triggers metastases in several cancer types such as breast and prostate cancer, but the specific role of the MSC factors in neuroblastoma metastasis is unclear. To better understand the effect of MSC secretome on chemokine receptors in neuroblastoma, and its role in metastasis, we studied a panel of 20 neuroblastoma cell lines, and compared their invasive potential towards MSC-conditioned-RPMI (mRPMI) and their cytokine receptor expression profiles. Western blot analysis revealed the expression of multiple CXCR4 isoforms in neuroblastoma cells. Among the five major isoforms, the expression of the 47 kDa isoform showed significant correlation with high invasiveness. Pretreatment with mRPMI up-regulated the expression of the 47 kDa CXCR4 isoform and also increased MMP-9 secretion, expression of integrin α3 and integrin β1, and the invasive potential of the cell; while blocking CXCR4 either with AMD 3100, a CXCR4 antagonist, or with an anti-47 kDa CXCR4 neutralizing antibody decreased the secretion of MMP-9, the expression of integrin α3 and integrin β1, and the invasive potential of the cell. Pretreatment with mRPMI also protected the 47 kDa CXCR4 isoform from ubiquitination and subsequent degradation. Our data suggest a modulatory role of the MSC secretome on the expression of the 47 kDa CXCR4 isoform and invasion potential of the neuroblastoma cells to the bone marrow.

The SK-N-AS human neuroblastoma cell line develops osteolytic bone metastases with increased angiogenesis and COX-2 expression

Neuroblastoma (NB), which arises from embryonic neural crest cells, is the most common extra-cranial solid tumor of childhood. Approximately half of NB patients manifest bone metastasis accompanied with bone pain, fractures and bone marrow failure, leading to disturbed quality of life and poor survival. To study the mechanism of bone metastasis of NB, we established an animal model in which intracardiac inoculation of the SK-N-AS human NB cells in nude mice developed osteolytic bone metastases with increased osteoclastogenesis. SK-N-AS cells induced the expression of receptor activator of NF-κB ligand and osteoclastogenesis in mouse bone marrow cells in the co-culture. SK-N-AS cells expressed COX-2 mRNA and produced substantial amounts of prostaglandin E₂ (PGE₂). In contrast, the SK-N-DZ and SK-N-FI human NB cells failed to develop bone metastases, induce osteoclastogenesis, express COX-2 mRNA and produce PGE₂. Immunohistochemical examination of SK-N-AS bone metastasis and subcutaneous tumor showed strong expression of COX-2. The selective COX-2 inhibitor NS-398 inhibited PGE₂ production and suppressed bone metastases with reduced osteoclastogenesis. NS-398 also inhibited subcutaneous SK-N-AS tumor development with decreased angiogenesis and vascular endothelial growth factor-A expression. Of interest, metastasis to the adrenal gland, a preferential site for NB development, was also diminished by NS-398. Our results suggest that COX2/PGE₂ axis plays a critical role in the pathophysiology of osteolytic bone metastases and tumor development of the SK-NS-AS human NB. Inhibition of angiogenesis by suppressing COX-2/PGE₂ may be an effective therapeutic approach for children with NB.

Plasma levels of soluble HLA-E and HLA-F at diagnosis may predict overall survival of neuroblastoma patients

The purpose of this study was to identify the plasma/serum biomarkers that are able to predict overall survival (OS) of neuroblastoma (NB) patients. Concentration of soluble (s) biomarkers was evaluated in plasma (sHLA-E, sHLA-F, chromogranin, and B7H3) or serum (calprotectin) samples from NB patients or healthy children. The levels of biomarkers that were significantly higher in NB patients were then analyzed considering localized or metastatic subsets. Finally, biomarkers that were significantly different in these two subsets were correlated with patient's outcome. With the exception of B7H3, levels of all molecules were significantly higher in NB patients than those in controls. However, only chromogranin, sHLA-E, and sHLA-F levels were different between patients with metastatic and localized tumors. sHLA-E and -F levels correlated with each other but not chromogranin. Chromogranin levels correlated with different event-free survival (EFS), whereas sHLA-E and -F levels also correlated with different OS. Association with OS was also detected considering only patients with metastatic disease. In conclusion, low levels of sHLA-E and -F significantly associated with worse EFS/OS in the whole cohort of NB patients and in patients with metastatic NB. Thus, these molecules deserve to be tested in prospective studies to evaluate their predictive power for high-risk NB patients.

Characterization of neuroblastoma bone invasion/metastasis in established bone metastatic model of SY5Y and KCNR cell lines

OBJECTS

To determine the mechanism of neuroblastoma (NB) bone invasion/metastasis, it is necessary to investigate the bone invasion/metastasis-related factors in the bone invasion/metastasis process. Some evidence has suggested that various proteins were involved in bone osteolytic response. The invasion/metastasis property and gene expression of NB, however, are still unknown.

METHODS

Single-cell suspensions of SY5Y and KCNR cells were injected directly into the femur of nude mice. Radiological and histological analyses, immunohistochemistry analyses, and western blot assay were performed to characterize bone metastasis mechanism in these bone metastasis models.

RESULTS

SY5Y and KCNR NB cells result in osteolytic responses in bone metastasis model. Osteoprotegerin (OPG), receptor activator of NF-kappaB ligand (RANKL), parathyroid hormone-related peptide (PTHrP), endothelin 1 (ET-1), and CXCR4 were examined and compared among in vitro, in vivo, and normal bone, respectively. PTHrP, OPG, RANKL, and ET-1 except CXCR4 in SY5Y and KCNR NB cells xenografts were strikingly upregulated compared with normal bone and NB cells. However, significantly stronger expression of PTHrP and RANKL was presented than ET-1 and OPG; furthermore, the ratios of expression of PTHrP, RANKL to OPG, and ET-1 were also markedly increased in vivo versus in vitro.

CONCLUSIONS

Our study provided evidence that NB cell may enhance bone invasion through PTHrP, OPG, RANKL, and ET-1, especially PTHrP and RANKL which may display stronger effects. CXCR4 appeared not participating in bone invasion, but in tumor growth, and homing to bone. Targeting PTHrP, OPG, ET-1, and RANKL may provide a new insight and method for patient therapy by inhibiting NB bone metastasis and invasiveness.

Establishment and characterization of xenograft models of human neuroblastoma bone metastasis

OBJECTS

To improve the therapy of advanced neuroblastoma (NB), it is critical to develop animal models that mimic NB bone metastases. Unlike the human disease, NB xenograft models rarely metastasize spontaneously to bone from the orthotopic site of primary tumor growth.

METHODS

Single-cell suspensions of SY5Y, KCNR NB cells were injected directly into the femur of nude mice. Radiological and histological analyses and immunohistochemistry analyses were performed to characterize these osseous NB models. SY5Y and KCNR result in osteolytic responses.

RESULTS

We have detected osteoprotegerin, receptor activator of nuclear factor kappa B ligand, parathyroid hormone-related protein, and endothelin-1, proteins associated with bone growth and osteolysis, and C-X-C chemokine receptor type 4 (CXCR4) involved in tumor growth and tumor cell migration in the NB cells grown in the bone.

CONCLUSIONS

These animal models can be used to study biological interactions, pathways, and potential therapeutic targets and also to evaluate new agents for treatment and prevention of NB bone metastasis.

Orthopaedic research in italy: state of the art

The most significant results in experimental and clinical orthopaedic research in Italy within the last three years have been primarily in major congenital diseases, bone tumors, regenerative medicine, joint replacements, spine, tendons and ligaments. The data presented in the following discussion is comparable with leading international results, highlighting Italian orthopaedic research excellemce as well as its shortcomings.

Serum levels of cytoplasmic melanoma-associated antigen at diagnosis may predict clinical relapse in neuroblastoma patients

The high molecular weight melanoma-associated antigen (HMW-MAA) and the cytoplasmic melanoma-associated antigen (cyt-MAA/LGALS3BP) are expressed in melanoma. Their serum levels are increased in melanoma patients and correlate with clinical outcome. We investigated whether these molecules can serve as prognostic markers for neuroblastoma (NB) patients. Expression of cyt-MAA and HMW-MAA was evaluated by flow cytometry in NB cell lines, patients' neuroblasts ((FI)-NB), and short-term cultures of these latter cells (cNB). LGALS3BP gene expression was evaluated by RT-qPCR on (FI)-NB, cNB, and primary tumor specimens. Soluble HMW-MAA and cyt-MAA were tested by ELISA. Cyt-MAA and HMW-MAA were expressed in NB cell lines, cNB, and (FI)-NB samples. LGALS3BP gene expression was higher in primary tumors and cNB than in (FI)-NB samples. Soluble cyt-MAA, but not HMW-MAA, was detected in NB cell lines and cNBs supernatants. NB patients' serum levels of both antigens were higher than those of the healthy children. High cyt-MAA serum levels at diagnosis associated with higher incidence of relapse, independently from other known risk factors. In conclusion, both HMW-MAA and cyt-MAA antigens, and LGALS3BP gene, were expressed by NB cell lines and patients' neuroblasts, and both antigens' serum levels were increased in NB patients. Elevated serum levels of cyt-MAA at diagnosis correlated with relapse, supporting that cyt-MAA may serve as early serological biomarker to individuate patients at higher risk of relapse that may require a more careful follow-up, after being validated in a larger cohort of patients at different time-points during follow-up. Given its immunogenicity, cyt-MAA may also be a potential target for NB immunotherapy.