Evaluation of the Effect of Mesenchymal Stem Cells on Cisplatin Induced Toxicity in Neuroblastoma Tumor Model

Objective: High-dose cisplatin (CDDP) causes dose-limiting side effects in neuroblastoma (NB) treatment. Mesenchymal stem cells (MSC) are a current research area. The aim of this study is to assess the interaction of MSC with CDDP in nude mouse NB model. Methods: Athymic male nude mice (n=28) thatbhad basal auditory tests, with subcutaneous NB were randomized to control, CDDP, MSC and CDDP+MSC treatment groups. Seven days later, hearing tests were repeatedand the animals were sacrificed. Necrosis, apoptosis and viabilitywere assessed in tumors. MSC rate within the tumor was assessed with flow cytometry for triple CD34+ CD44+ and CD117- expression. Expression of the cochlear cell proteins of calretinin, math-1 and myosin2A were immunohistochemically assessed. Results: Tumor tissues were found to have statistically significantly higher levels of necrosis in CDDP and CDDP+MSC groups. MSC did not change the tumor dimensions in the CDDP group. MSC group had higher triple CD34+ CD44+ and CD117- expression within tumor tissue compared to the control and CDDP groups. In the inner ear, the expression of cochlear cell proteins calretinin, math-1 and myosin2A were identified to be highest in MSC group. 15-decibel loss at 12, 16, 20 and 32 kHz frequencies with CDDP was resolved with MSC administration. Conclusion: MSC prevented hearing loss caused by CDDP without disrupting the antitumor effect of CDDP. Systemic MSC may be assessed for clinical use to reduce the side effects of CDDP.

Reciprocal impacts of telomerase activity and ADRN/MES differentiation state in neuroblastoma tumor biology

Telomere maintenance and tumor cell differentiation have been separately implicated in neuroblastoma malignancy. Their mechanistic connection is unclear. We analyzed neuroblastoma cell lines and morphologic subclones representing the adrenergic (ADRN) and mesenchymal (MES) differentiation states and uncovered sharp differences in their telomere protein and telomerase activity levels. Pharmacologic conversion of ADRN into MES cells elicited consistent and robust changes in the expression of telomere-related proteins. Conversely, stringent down-regulation of telomerase activity triggers the differentiation of ADRN into MES cells, which was reversible upon telomerase up-regulation. Interestingly, the MES differentiation state is associated with elevated levels of innate immunity factors, including key components of the DNA-sensing pathway. Accordingly, MES but not ADRN cells can mount a robust response to viral infections in vitro. A gene expression signature based on telomere and cell lineage-related factors can cluster neuroblastoma tumor samples into predominantly ADRN or MES-like groups, with distinct clinical outcomes. Our findings establish a strong mechanistic connection between telomere and differentiation and suggest that manipulating telomeres may suppress malignancy not only by limiting the tumor growth potential but also by inducing tumor cell differentiation and altering its immunogenicity.

p53-Mediated Radiosensitization of 177Lu-DOTATATE in Neuroblastoma Tumor Spheroids

p53 is involved in DNA damage response and is an exciting target for radiosensitization in cancer. Targeted radionuclide therapy against somatostatin receptors with 177Lu-DOTATATE is currently being explored as a treatment for neuroblastoma. The aim of this study was to investigate the novel p53-stabilizing peptide VIP116 in neuroblastoma, both as monotherapy and together with 177Lu-DOTATATE. Five neuroblastoma cell lines, including two patient-derived xenograft (PDX) lines, were characterized in monolayer cultures. Four out of five were positive for 177Lu-DOTATATE uptake. IC50 values after VIP116 treatments correlated with p53 status, ranging between 2.8–238.2 μM. IMR-32 and PDX lines LU-NB-1 and LU-NB-2 were then cultured as multicellular tumor spheroids and treated with 177Lu-DOTATATE and/or VIP116. Spheroid growth was inhibited in all spheroid models for all treatment modalities. The most pronounced effects were observed for combination treatments, mediating synergistic effects in the IMR-32 model. VIP116 and combination treatment increased p53 levels with subsequent induction of p21, Bax and cleaved caspase 3. Combination treatment resulted in a 14-fold and 1.6-fold induction of MDM2 in LU-NB-2 and IMR-32 spheroids, respectively. This, together with differential MYCN signaling, may explain the varying degree of synergy. In conclusion, VIP116 inhibited neuroblastoma cell growth, potentiated 177Lu-DOTATATE treatment and could, therefore, be a feasible treatment option for neuroblastoma.

Systematic review of the receptor tyrosine kinase superfamily in neuroblastoma pathophysiology

Background Neuroblastoma is a devastating disease accounting for 15% of all childhood cancer deaths. Yet, our understanding of key molecular drivers such as receptor tyrosine kinases (RTKs) in this pathology remains poorly clarified. Here, we provide a systematic analysis of the RTK superfamily in the context of neuroblastoma pathogenesis. Methods Statistical correlations for all RTK family members’ expression to neuroblastoma patient survival across 10 independent patient cohorts were annotated, synthesized, and ranked using the R2: Genomics Analysis and Visualization Platform. Gene expression of selected members across different cancer cell lines was further analyzed in the Cancer Cell Line Encyclopedia, part of the Cancer Dependency Map portal (depmap portal (http://depmap.org)). Finally, we provide a detailed literature review for highly ranked candidates. Results Our analysis defined two subsets of RTKs showing robust associations with either better or worse survival, constituting potential novel players in neuroblastoma pathophysiology, diagnosis, and therapy. We review the available literature regarding the oncogenic functions of these RTKs, their roles in neuroblastoma pathophysiology, and potential utility as therapeutic targets. Conclusions Our systematic analysis and review of the RTK superfamily in neuroblastoma pathogenesis provides a new resource to guide the research community towards focused efforts investigating signaling pathways that contribute to neuroblastoma tumor establishment, growth, and/or aggressiveness and targeting these druggable molecules in novel therapeutic strategies.

Norepinephrine transporter analog benzylguanidine-conjugated nanoparticles for the delivery of paclitaxel in neuroblastoma

Aim: We previously synthesized a polyethylene glycol-based norepinephrine transporter-targeted agent, BG-P-TAT, which has a benzylguanidine and a triazolyl-tetrac group. This targeted conjugate showed suppression of neuroblastoma tumor progression. In this study we aimed to synthesize nanoparticles to encapsulate the chemotherapeutic agent paclitaxel for targeting neuroblastoma tumors by using benzylguanidine so that it can compete with norepinephrine for uptake by neuroendocrine cells. Methods: Biocompatible poly(lactide-co-glycolic acid)-polyethylene glycol was chosen to prepare targeted nanoparticles for safe delivery of the chemotherapy agent paclitaxel. Result: Paclitaxel concentration was 60% higher in neuroblastoma tumors of mice treated with paclitaxel encapsulated in targeted nanoparticles than with non-targeted nanoparticles. Conclusion: These findings support the targeted delivery of paclitaxel as a chemotherapeutic agent for neuroblastoma.

MEIS2 Is an Adrenergic Core Regulatory Transcription Factor Involved in Early Initiation of TH-MYCN-Driven Neuroblastoma Formation

Roughly half of all high-risk neuroblastoma patients present with MYCN amplification. The molecular consequences of MYCN overexpression in this aggressive pediatric tumor have been studied for decades, but thus far, our understanding of the early initiating steps of MYCN-driven tumor formation is still enigmatic. We performed a detailed transcriptome landscaping during murine TH-MYCN-driven neuroblastoma tumor formation at different time points. The neuroblastoma dependency factor MEIS2, together with ASCL1, was identified as a candidate tumor-initiating factor and shown to be a novel core regulatory circuit member in adrenergic neuroblastomas. Of further interest, we found a KEOPS complex member (gm6890), implicated in homologous double-strand break repair and telomere maintenance, to be strongly upregulated during tumor formation, as well as the checkpoint adaptor Claspin (CLSPN) and three chromosome 17q loci CBX2, GJC1 and LIMD2. Finally, cross-species master regulator analysis identified FOXM1, together with additional hubs controlling transcriptome profiles of MYCN-driven neuroblastoma. In conclusion, time-resolved transcriptome analysis of early hyperplastic lesions and full-blown MYCN-driven neuroblastomas yielded novel components implicated in both tumor initiation and maintenance, providing putative novel drug targets for MYCN-driven neuroblastoma.

Verification of Genetic Differences and Immune Cell Infiltration Subtypes in Neuroblastoma Tumor Microenvironment for Immunotherapy

Background: The tumor microenvironment (TME) has achieved remarkable results in the research of cancer progression in the past few years. it is crucial to understand the nature and function of TME in tumors because of precise treatment strategies for individual cancers having received widespread attention, including immunotherapy. The immune infiltrative profiles of neuroblastoma (NB) have not yet been completely illustrated. The purpose of this research is to analyses tumor immune cell infiltration (ICI) in the microenvironment of NB.Methods: We applied CIBERSORT and ESTIMATE algorithms to evaluate the ICI status of 438 NB samples. Three ICI models were selected and ICI scores were acquired. Subgroups with high ICI scores based on immune activation signaling pathways have better overall survival. Results: The genes of immunosuppressive glycosaminoglycan biosynthesis heparan sulfate signaling pathway were markedly enriched in the low ICI score subgroup. It was inferred that compared with low ICI NB subtypes, patients with high ICI NB subtypes were more likely to respond to immunotherapy and a better prognosis. Conclusion: Notably, our ICI scores not only provided new clinical and theoretical basis for mining NB prognostic markers related to the microenvironment, but also aided new ideas for the development of new NB precision immunotherapy methods.

Reciprocal impacts of telomerase activity and tumor cell differentiation in neuroblastoma tumor biology

Telomere maintenance and tumor cell differentiation have been separately implicated in neuroblastoma malignancy. Their mechanistic connection is unclear. We analyzed neuroblastoma cell lines and morphologic subclones representing the adrenergic (ADRN) and mesenchymal (MES) differentiation states and uncovered sharp differences in their telomere protein and telomerase activity levels. Pharmacologic conversion of ADRN into MES cells elicited consistent and robust changes in the expression of telomere-related proteins. Conversely, stringent down-regulation of telomerase activity triggers the differentiation of ADRN into MES cells, which was reversible upon telomerase up-regulation. Interestingly, the MES differentiation state is associated with elevated levels of innate immunity factors, including key components of the DNA-sensing pathway. Accordingly, MES but not ADRN cells can mount a robust response to viral infections in vitro. A gene expression signature based on telomere and cell lineage-related factors can cluster neuroblastoma tumor samples into predominantly ADRN or MES-like groups, with distinct clinical outcomes. Our findings establish a novel mechanistic connection between telomere and differentiation and suggest that manipulating telomeres may suppress malignancy not only by limiting the tumor growth potential but also by inducing tumor cell differentiation and altering its immunogenicity.