FOXM1, MEK, and CDK4/6: New targets for MPNST therapy

Malignant peripheral nerve sheath tumors (MPNSTs) are deadly sarcomas that desperately need effective therapies. Half of all MPNSTs arise in patients with Neurofibromatosis Type I (NF1), a common inherited disease. NF1 patients can develop benign lesions called Plexiform Neurofibromas (PNFs), often in adolescence, and over time some PNFs, but not all, will transform into MPNSTs. A deeper understanding of the molecular and genetic alterations driving PNF-MPNST transformation will guide development of more targeted and effective treatments for these patients. This review focuses on an oncogenic transcription factor, FOXM1, that is a powerful oncogene in other cancers but little studied in MPNSTs. Elevated expression of FOXM1 was seen in patient MPNSTs and correlated with poor survival, but otherwise its role in the disease is unknown. We discuss what is known about FOXM1 in MPNSTs relative to other cancers and how FOXM1 may be regulated by and/or regulate the most commonly altered players in MPNSTs, particularly in the MEK and CDK4/6 kinase pathways. We conclude by considering FOXM1, MEK, and CDK4/6 as new, clinically relevant targets for MPNST therapy.