Modulation of chemotherapeutic drug resistance in neuroblastoma SK‐N‐AS cells by the neural apoptosis inhibitory protein and miR‐520f

• Published in: International journal of cancer Vol. 136; no. 7; pp. 1579 - 1588
• Main Authors: Harvey, Harry, Piskareva, Olga, Creevey, Laura, Alcock, Leah C., Buckley, Patrick G, O'Sullivan, Maureen J., Segura, Miguel F., Gallego, Soledad, Stallings, Raymond L., Bray, Isabella M.
• Format: Journal Article
• Language: English
• Published: United States Wiley Subscription Services, Inc 01.04.2015
• Subjects: Antineoplastic Agents - pharmacology; Antineoplastic Agents - therapeutic use; Apoptosis; Cancer; Cell Line, Tumor; Chemotherapy; Chromosomes; cisplatin; Cisplatin - pharmacology; Comparative Genomic Hybridization; Drug resistance; Drug Resistance, Neoplasm - genetics; Gene Expression; Gene Expression Regulation, Neoplastic; Genomics; Humans; Medical research; MicroRNAs; MicroRNAs - genetics; miR‐520f; NAIP; neuroblastoma; Neuroblastoma - drug therapy; Neuroblastoma - genetics; Neuronal Apoptosis-Inhibitory Protein - genetics; Phenotype; Proteins; RNA Interference; neuroblastoma; drug-resistance; miR-520f; cisplatin; NAIP
• ISSN: 0020-7136; 1097-0215
• DOI: 10.1002/ijc.29144

The acquisition of multidrug resistance is a major impediment to the successful treatment of neuroblastoma, a clinically heterogeneous cancer accounting for ∼15% of all pediatric cancer deaths. The MYCN transcription factor, whose gene is amplified in ∼30% of high‐risk neuroblastoma cases, influences drug resistance by regulating a cadre of genes, including those involved with drug efflux, however, other high‐risk subtypes of neuroblastoma lacking MYCN amplification, such as those with chromosome 11q deletions, also acquire multidrug resistance. To elucidate additional mechanisms involved with drug resistance in non‐MYCN amplified tumour cells, an SK‐N‐AS subline (SK‐N‐AsCis24) that is significantly resistant to cisplatin and cross resistant to etoposide was developed through a pulse‐selection process. High resolution aCGH analysis of SK‐N‐AsCis24 revealed a focal gain on chromosome 5 containing the coding sequence for the neural apoptosis inhibitory protein (NAIP). Significant overexpression of NAIP mRNA and protein was documented, while experimental modulation of NAIP levels in both SK‐N‐AsCis24 and in parental SK‐N‐AS cells confirmed that NAIP was responsible for the drug resistant phenotype by apoptosis inhibition. Furthermore, a decrease in the NAIP targeting microRNA, miR‐520f, was also demonstrated to be partially responsible for increased NAIP levels in SK‐N‐AsCis24. Interestingly, miR‐520f levels were determined to be significantly lower in postchemotherapy treatment tumours relative to matched prechemotherapy samples, consistent with a role for this miRNA in the acquisition of drug resistance in vivo, potentially through decreased NAIP targeting. Our findings provide biological novel insight into neuroblastoma drug‐resistance and have implications for future therapeutic research. What's new? Just under one‐third of high‐risk neuroblastomas, in which drug resistance is a central feature, involve amplification of the MYCN gene. Resistance in remaining high‐risk tumors may be determined by any of several non‐MYCN amplification mechanisms. Here, analysis of an SK‐N‐AS subline (SK‐N‐AsCis24) lacking MYCN amplification but resistant to cisplatin and etoposide reveals a link between the development of drug resistance via apoptotic inhibition and the neural apoptosis inhibitory protein (NAIP) and its regulatory microRNA, miR‐520f. NAIP upregulation was associated with DNA copy number gain on chromosome 5 and down‐regulation of miRNA‐520f. MiR‐520f was discovered to be down‐regulated post‐chemotherapy.