Introduction

Neuroblastoma (NB) is the most frequent extracranial solid tumor in children, accounting for 8-10% of all pediatric cancers1. These tumors originate from neural crest cells, which are primitive progenitors of sympathetic ganglia, and can arise anywhere along the sympathetic nervous system 2. After tumor formation, it results in a spectrum of clinical diseases ranging from variably aggressive NBs to well-differentiated benign tumors (i.e., ganglioneuroma, GN) 3. Metastases are diagnosed in about 50% of patients, with the bone marrow, bone, and regional lymph nodes being
the most commonly affected sites 4. NB treatment includes a wide range of therapies, depending on patients’ disease risk classification 1. After induction and consolidation chemotherapy, approximately half of all patients reportedly develop drug resistance or suffer disease relapse after the first-line therapy5, 6.
The International NB staging system (INSS) classifies NBs into different stages (1, 2A/B, 3, 4, and 4S) based on clinical criteria7, 8. In addition, the MYCNoncogene amplification (MNA) is an independent poor prognostic factor significantly associated with INSS stage 4, and unfavorable histological features 9. Determination of tumor cell ploidy and the identification of segmental chromosomal aberrations found most frequently in 1p, 1q, 3p, 11q, 14q, and 17p have substantially improved NB risk stratification and the choice of the most effective treatment regimens 9. Specifically, LOH in chromosome 11q (Ch11q) in nonamplified-MYCN (NAMN) was found to be associated with a therapy-resistant metastatic NB subgroup 10, as well as with high activity of the COX/microsomal prostaglandin E synthase (mPGES)-1/PGE2 pathway 11.
Prostaglandins (PGs, including PGD2, PGE2, PGF2a, and PGI2) are arachidonic acid-derived chemical mediators of the inflammatory response12. They are produced by sequential actions of cyclooxygenases (COX-1 or COX-2) and specific synthases, exerting their effects mainly through the G-protein–coupled receptors (GPCRs), activating adenylate cyclase or phospholipase C 12. Tumor cells are often characterized by aberrant COX-2 expression, resulting from transcriptional and/or post-transcriptional and epigenetic alterations 13, 14. COX-2, which is also released by cancer-associated fibroblasts (CAFs) and type-2 macrophages (M2) 15, is involved in angiogenesis, tumor cell proliferation, and survival. It correlates with invasiveness and resistance to chemotherapeutic drugs in many cancer types, such as breast, lung, colon, prostate, and bladder 16, 17. In NBs, high COX-2/PGE2 expression levels promote malignant cell transformation and inhibit apoptosis via cAMP-mediated β-catenin stabilization, a process that may be of particular significance in NAMN cells 18.
Despite the premise that the COX-2 pathway favors tumor progression, the exact extent of this association has not yet been completely understood. Network systems biology has been broadly accepted as useful tools that allow the visualization and analysis of the interaction of multiple molecular pathways, providing the uncovering of new biomarkers and their association to disease phenotypes 19. In the current study, we analyzed COX-2 expression levels in NB tumor samples obtained during diagnosis and post-chemotherapy. Furthermore, we analyzed the genomic profile of tumors with Ch11q aberrations and the correlation with the genes encoding the enzymes involved in the COX/mPGES-1/PGE2 and other inflammatory pathways using a pipeline of computational systems biology tools.