A systematic review of 89 studies has identified 53 microRNAs with documented roles in the differentiation of neuroblastoma cells, the most common extracranial solid tumor in children under five years of age. The review, conducted by researchers at the University of California, Davis and published in Frontiers in Oncology, highlights three microRNA groups—miR-124, miR-34, and miR-506-3p—that consistently promote differentiation of neuroblastoma cells toward a more mature phenotype in preclinical models, alongside the miR-17–92 cluster, which antagonizes differentiation and is associated with poor survival. Disruption of the pro-differentiation microRNAs is correlated with decreased overall survival in patients, and the authors argue that these molecules may represent novel therapeutic candidates for a disease in which high-risk cases still carry an overall survival of only around 40 percent despite aggressive multimodal treatment.
The review followed the PRISMA 2020 recommendations, searching Ovid MEDLINE and Embase from database inception to June 2023. After de-duplication, 396 potentially relevant unique articles underwent abstract and full-text screening, yielding 89 articles that met the selection criteria of addressing microRNAs, differentiation, and neuroblastoma. From these, the researchers catalogued 53 entries comprising individual microRNAs and microRNA groups with a role in neuroblastoma differentiation.
The authors selected four microRNA groups for detailed narrative discussion based on objective criteria: each had at least five independent studies, validated functional data from both gain-of-function and loss-of-function experiments, demonstrated clinical correlations with patient outcomes, and represented both pro-differentiation and anti-differentiation mechanisms. Neuroblastoma arises from embryonic neural crest cells that fail to migrate and differentiate appropriately along the sympathetic nervous system, forming tumors in the adrenal medulla and sympathetic ganglia of the chest, head, neck, abdomen, and pelvis. Approximately half of all cases are classified as high-risk, and while low- and intermediate-risk disease achieves overall survival greater than 90 percent, high-risk tumors demonstrate aggressive invasion, early metastasis, and frequent relapse.
The current standard differentiation therapy, the vitamin A derivative 13-cis retinoic acid, decreases cell proliferation and promotes maturation during the maintenance phase of treatment, but responses are variable and may not be sustained after treatment ends, leaving relapse rates high. Understanding the molecular mechanisms governing differentiation may therefore open new therapeutic avenues. miR-124 emerged as the most well-studied inducer of differentiation in neuroblastoma.
Encoded by three genomic loci and highly expressed in neuronal tissues, miR-124 is upregulated in neuroblastoma cells following retinoic acid-induced differentiation, and its ectopic expression transforms spherical, undifferentiated cells into cells with extended neurites forming neuronal networks, with increased expression of differentiation markers including β-Tubulin III, MAP2, SYN, NF-M, and Nestin. Mechanistically, the polypyrimidine tract-binding protein PTBP1 binds the immature Pri-miR-124-1 transcript and blocks its maturation, thereby preventing neuronal differentiation; during differentiation, Pri-miR-124-2 escapes this inhibition, matures, and in turn inhibits PTBP1, creating a self-reinforcing loop. miR-124 also downregulates the histone methyltransferase EZH2 to drive neuronal differentiation, suppresses CDK4, CDK6, STAT3, E2F3, and BCL2 to induce differentiation, apoptosis, and cell-cycle arrest, inhibits retinoic acid receptor gamma, and represses genes activated by the transcription factor ELF4, a leading candidate for maintaining neuroblastoma in an undifferentiated state. Notably, miR-124-2-3p is hypermethylated in 25 percent of high-risk neuroblastoma samples, suggesting epigenetic silencing may contribute to high-risk disease.
The miR-34 family—miR-34a, miR-34b, and miR-34c—acts as a tumor suppressor downstream of the p53 and TAp73 pathways. In the SH-SY5Y cell line, increased miR-34a levels are associated with increased p53, and inhibiting either miR-34a or TAp73 reduces neurite growth during retinoic acid-induced differentiation. miR-34a antagonizes the proliferation-driving transcription factor E2F3, decreases survivin, Cyclin D3, and c-MYC, and directly inhibits MYCN by targeting its 3′ untranslated region in human neuroblastoma specimens, impairing proliferation and inducing differentiation. Treatment with pre-miR-34a significantly increases caspase-3 and caspase-7 activity, and miR-34a also targets LYAR and CTCF to induce differentiation. miR-34b and miR-34c are typically suppressed in neuroblastoma through promoter hypermethylation; restoring their levels reduces proliferation and promotes differentiation, with miR-34b targeting CCNE2 and E2F3 to induce G1 phase arrest.
Clinically, low miR-34a expression is associated with high-risk disease and worse prognosis, while miR-34b expression is significantly higher in patients who survived more than five years compared to those who did not. miR-506-3p has attracted attention for its potent differentiation-inducing effects and its relationship with MYCN, the most common oncogene in neuroblastoma and a marker of worse prognosis. Treatment with miR-506-3p increases the differentiation factors βIII-tubulin, neuron-specific enolase, and growth-associated protein 43, and produces a dose-dependent increase in neurite outgrowth in BE(2)-C cells that correlates directly with reduced cell viability.
The microRNA downregulates MYCN through the intermediary PLAGL2, a promoter of MYCN transcription that is itself regulated by miR-506-3p; PLAGL2 knockdown induces differentiation, reduces proliferation, and decreases cell survival. miR-506-3p also suppresses CDK4 and STAT3, and suppressing both produces significantly greater neurite growth than suppressing either alone. Strikingly, miR-506-3p levels are essentially non-existent in MYCN-amplified tumors, and even truncated analogs lacking up to two nucleotides retain differentiation-inducing activity, a property that may lower manufacturing costs and reduce non-specific toxicity due to smaller molecular size. In contrast, the miR-17–92 cluster—involving miR-17, miR-18, miR-19, miR-20, and miR-92, transcribed as a single polycistronic unit—inhibits neuroblastoma differentiation and contributes to enhanced tumorigenesis.
The cluster is regulated by MYCN and directly represses genes involved in differentiation, particularly nuclear hormone receptors such as the glucocorticoid receptor and estrogen receptor-alpha. Reduced levels of these receptors correlate with low expression of the differentiation markers TrkA, p75NTR, and SCG2. The cluster also inhibits RUNX1 and RUNX3, master transcription factors in neuronal lineage differentiation, and is downregulated upon differentiation induced by brain-derived neurotrophic factor.
Inhibiting the cluster upregulates the differentiation markers BCL2, MEF2D, and MAP3K12. Clinically, the cluster, especially miR-18a, is highly expressed in MYCN-amplified tumors compared to normal adrenal tissue, and loss of its downstream target, the glucocorticoid receptor, correlates with poor overall survival. Beyond these four groups, the review catalogued 49 additional microRNAs that converge on recurring regulatory themes.
A subset including miR-143-3p, miR-145, miR-192, miR-203a, and miR-432 is transcriptionally induced by p53 and limits proliferation while promoting differentiation-associated phenotypes. Another cluster—miR-125a, miR-494, miR-495, and miR-543—targets or is co-regulated with PHOX2B, a master transcription factor of sympathetic neuronal differentiation. Others act on epigenetic machinery, with miR-152 targeting DNMT1, miR-130a-3p and miR-432 targeting MeCP2, and miR-137 targeting the histone demethylase KDM1A, while miR-23a-24-27 and miR-129a promote differentiation by targeting Notch1.
Importantly, not all microRNAs promote differentiation: miR-221, miR-222-3p, miR-335, and miR-375 favor a non-neuronal or less-differentiated phenotype, supporting a bidirectional model in which specific microRNAs can either promote or restrain the differentiated state. Differentiation and apoptosis appear frequently co-regulated, with several microRNAs converging on regulators of programmed cell death. Translating these findings into therapy faces substantial barriers, and the authors are explicit that no clinical therapeutic trials of microRNAs in neuroblastoma have been conducted.
Of the included studies, 73 percent were conducted in vitro using established cell lines, only 6.7 percent used xenograft models, and 20.2 percent analyzed clinical tumor specimens; the certainty of evidence for all summarized outcomes was rated low using a GRADE-informed framework because the data are entirely preclinical. Experience from other cancers underscores the risks: the MRX34 trial of a liposomal miR-34a mimic in advanced solid tumors was terminated after serious immune-mediated adverse events resulted in four patient deaths despite dexamethasone premedication, and the TargomiR trial of a miR-16 mimic in mesothelioma was dose-limited by inflammatory toxicity. Naked microRNA mimics are rapidly degraded by serum nucleases, cleared by the kidneys, and poorly taken up by target cells, and while nanoparticle delivery systems have shown improved stability and tumor targeting in preclinical models, none have been validated in pediatric neuroblastoma patients.
A more immediate clinical role may lie in biomarkers rather than therapeutics. Cooperative groups including the Children's Oncology Group and European high-risk trials in Germany and the Netherlands have incorporated liquid biopsy analysis of circulating microRNAs, with microRNA panels demonstrating improved sensitivity and prognostic value in predicting treatment response, relapse risk, and recurrence detection compared to current surveillance approaches. The review's authors conclude that microRNAs function as active regulators of differentiation rather than passive markers, supported by gain- and loss-of-function experiments across multiple cell lines and independent laboratories, and that combinatorial microRNA strategies spanning the p53, PHOX2B, MYCN, and Notch pathways may ultimately prove more effective than single-agent approaches.
For now, however, the promise of microRNA differentiation therapy in high-risk neuroblastoma remains preclinical, awaiting advances in delivery, safety, and clinical trial data.
Subject of Research: The role of microRNAs in neuroblastoma cell differentiation and their therapeutic potential
Article Title: The role of microRNAs in neuroblastoma cell differentiation and their therapeutic potential: a systematic review
Article References: Sulman, M., Doyle, K. E., Studer, A. C., & Brown, E. G. (2026). The role of microRNAs in neuroblastoma cell differentiation and their therapeutic potential: a systematic review. Frontiers in Oncology, 16, Article 1836015. https://doi.org/10.3389/fonc.2026.1836015
Image Credits: AI Generated
DOI: 10.3389/fonc.2026.1836015
Keywords: neuroblastoma, microRNAs, cell differentiation, miR-124, miR-34, miR-506-3p, miR-17-92 cluster, MYCN, pediatric oncology, systematic review, retinoic acid, liquid biopsy
News Source: Nathaniel Bowman. (October 24, 2026). MicroRNAs That Steer Neuroblastoma Cell Differentiation Emerge as Future Therapy Candidates. Scienmag.
