# MYCN inhibits TrkC-mediated differentiation in neuroblastoma cells via disruption of the PKA signalling pathway

## TL;DR

This study shows that MYCN blocks TrkC's ability to promote differentiation in neuroblastoma cells by disrupting the PKA signaling pathway, offering new therapeutic insights.

## Contribution

The study reveals a novel mechanism by which MYCN inhibits TrkC-mediated differentiation through the PKA signaling pathway in neuroblastoma.

## Key findings

- TrkC promotes differentiation in non-MYCN-amplified cells but proliferation in MYCN-overexpressing cells.
- MYCN knockdown enhances PKA/CREB signaling and induces differentiation in MYCN-amplified cells.
- MYCN-induced miR-221 suppresses CREB expression, linking it to reduced PKA pathway activity in tumors.

## Abstract

Neuroblastoma is a rare childhood cancer in which high-risk disease, frequently driven by MYCN amplification, has poor survival. Trk-receptor expression correlates with prognosis: TrkA is observed in low-risk cases while TrkB is often expressed in high-risk MYCN-amplified neuroblastoma. However, TrkC’s role in neuroblastoma genesis remains unclear. This study investigates the interplay between TrkC signalling and MYCN status. Using neuroblastoma cell lines with varying MYCN levels, we found that TrkC activation leads to neuronal differentiation in MYCN non-amplified cells but promotes proliferation in MYCN-overexpressing and MYCN-amplified cells. Temporal phosphoproteomic analysis identified the PKA pathway as crucial for TrkC-mediated differentiation. Manipulating PKA signalling altered cell fate in vitro and in zebrafish xenografts. In MYCN-amplified cells, MYCN knockdown enhanced PKA/CREB signalling and induced differentiation. Similarly, overexpression of constitutively active PKA or CREB promoted differentiation, confirming the role of PKA/CREB pathway in driving differentiation. Analysis of patient data revealed reduced expression of PKA pathway genes in MYCN-amplified tumours. Additionally, MYCN-induced miR-221 was found to suppress CREB expression. Together, these findings demonstrate MYCN-dependent effects of TrkC signalling and highlight the therapeutic potential of targeting the PKA pathway to induce differentiation in high-risk MYCN-amplified neuroblastoma.