Netrin–DCC inhibition suppresses neuroendocrine neoplasm growth in vivo

DCC protein functions as a tumor suppressor and is altered in various tumors, including neuroendocrine neoplasms. Netrin (NTN)-1 serves as the primary ligand for DCC. Acting as a dependence receptor, DCC induces apoptosis in the absence of NTN and promotes cell survival when NTN is present. In certain cancers, such as small-cell lung cancer and neuroblastoma, the upregulation of NTN-3 has been observed instead of NTN-1. However, the exact role of NTNs and DCC in PNEN remains unclear. We assessed DCC and netrin expression in pancreatic neuroendocrine neoplasm (PNEN) cells (BON-1). We examined the effect of netrin on cell viability using DCC knockdown and NP137, a netrin-inhibiting antibody. In vivo, PNEN cells were injected into nude mice and treated with NP137 or PBS. Tumor RNA sequencing was performed. A population-based analysis using TCGA data evaluated the impact of DCC and NTN3 expression on survival. BON-1 cells exhibited elevated expression of DCC and NTN-3. The addition of NTN-1 augmented BON-1 viability, a response that was lessened upon NTN blockade using NP137. Furthermore, DCC siRNA negated the effect of NTN-1 on cell viability. Mice bearing PNEN BON-1 xenografts treated with NP137 exhibited markedly diminished xenograft growth. RNA sequencing revealed upregulation of small nucleolar RNAs (SNORs) in NP137-treated tumors, with enriched pathways related to RNA processing. TCGA analysis showed a negative correlation between NTN3 expression and survival. In conclusion, our data suggest that NTN-3, NTN-1, and DCC have interdependent oncogenic roles in PNENs, which can be reversed by blocking NTN binding to DCC.