Neuregulin-1 overexpression and Trp53 haploinsufficiency cooperatively promote de novo malignant peripheral nerve sheath tumor pathogenesis

Division of Neuropathology, Department of Pathology, The University of Alabama at Birmingham, 1720 Seventh Avenue South, SC930G3, Birmingham, AL, 35294-0017, USA.
Acta Neuropathologica (Impact Factor: 9.78). 11/2013; 127(4). DOI: 10.1007/s00401-013-1209-3
Source: PubMed

ABSTRACT Malignant peripheral nerve sheath tumors (MPNSTs) are Schwann cell-derived malignancies that arise from plexiform neurofibromas in patients with mutation of the neurofibromin 1 (NF1) gene. We have shown that the growth factor neuregulin-1 (NRG1) also contributes to human neurofibroma and MPNST pathogenesis and that outbred C57BL/6J × SJL/J transgenic mice overexpressing NRG1 in Schwann cells (P0-GGFβ3 mice) recapitulate the process of neurofibroma-MPNST progression. However, it is unclear whether NRG1 acts predominantly within NF1-regulated signaling cascades or instead activates other essential cascades that cooperate with NF1 loss to promote tumorigenesis. We now report that tumorigenesis is suppressed in inbred P0-GGFβ3 mice on a C57BL/6J background. To determine whether NRG1 overexpression interacts with reduced Nf1 or Trp53 gene dosage to "unmask" tumorigenesis in these animals, we followed cohorts of inbred P0-GGFβ3;Nf1 (+/-), P0-GGFβ3;Trp53 (+/-) and control (P0-GGFβ3, Nf1 (+/-) and Trp53 (+/-)) mice for 1 year. We found no reduction in survival or tumors in control and P0-GGFβ3;Nf1 (+/-) mice. In contrast, P0-GGFβ3;Trp53 (+/-) mice died on average at 226 days, with MPNSTs present in 95 % of these mice. MPNSTs in inbred P0-GGFβ3;Trp53 (+/-) mice arose de novo from micro-MPNSTs that uniformly develop intraganglionically. These micro-MPNSTs are of lower grade (WHO grade II-III) than the major MPNSTs (WHO grade III-IV); array comparative genomic hybridization showed that lower grade MPNSTs also had fewer genomic abnormalities. Thus, P0-GGFβ3;Trp53 (+/-) mice represent a novel model of low- to high-grade MPNST progression. We further conclude that NRG1 promotes peripheral nervous system neoplasia predominantly via its effects on the signaling cascades affected by Nf1 loss.

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