We have previously shown that expression of the p75 neurotrophin receptor (p75NTR) enhances apoptosis induction and mitochondrial accumulation of reactive oxygen species by 4-HPR in neuroblastoma cells.
Chemotherapy-resistant neuroblastoma cells typically have Schwann cell-like ("S-type") morphology and express the p75 neurotrophin receptor (p75NTR). p75NTR has been previously shown to modulate the redox state of neural crest tumor cells.
Furthermore, romidepsin induces expression of genes such as p21 and expression of p75 and NTRK (TrkA) which are more highly expressed in the tumors from NB patients that have a good prognosis.
Ectopic p75 expression in the SH-SY5Y neuroblastoma cell line significantly reduced proliferation, increased the fraction of apoptotic cells in vitro and resulted in a loss of tumorigenicity in nude mice.
In a series of studies using, in turn, neuroblastoma cell lines that express only p75, mutant NGF species that bind selectively to either p75 or trkA, and a polyclonal antibody that binds to the NGF-binding domain of p75, we demonstrate that NGF binding to p75 is both necessary and sufficient for the abrogation of apoptosis in neuroblastoma cells treated with antimitotic agents.