Preclinical in vivo evaluation of rapamycin in human malignant peripheral nerve sheath explant xenograft

• Published in: International journal of cancer 2010-01, Vol.126 (2), p.563-571
• Main Authors: Bhola, Priya, Banerjee, Sutapa, Mukherjee, Joydeep, Balasubramanium, Anand, Arun, Vedant, Karim, Zia, Burrell, Kelly, Croul, Sidney, Gutmann, David H., Guha, Abhijit
• Format: Article
• Language: English
• Subjects: 1-Phosphatidylinositol 3-kinase; AKT protein; Angiogenesis; Animal models; Animals; Antibiotics, Antineoplastic - pharmacology; Apoptosis; Apoptosis - drug effects; Blotting, Western; Cancer; Chemotherapy; Cyclin D1 - metabolism; Dose-Response Relationship, Drug; Drug Evaluation, Preclinical; Drug resistance; Genetic disorders; Humans; Immunohistochemistry; Kinases; Male; Malignant Peripheral Nerve Sheath Tumor; Mammalian Target of Rapamycin; Medical research; Metastases; Mice; Mice, Inbred NOD; Mice, SCID; Neurofibromatosis; Neurofibromatosis 1 - drug therapy; Neurofibromatosis 1 - metabolism; Neurofibromatosis 1 - pathology; Neurofibromin; Neurofibromin 1; Neurological disorders; Peripheral nerves; Peripheral Nervous System Neoplasms - drug therapy; Peripheral Nervous System Neoplasms - metabolism; Peripheral Nervous System Neoplasms - pathology; Protein Kinases - metabolism; Proto-Oncogene Proteins c-akt - metabolism; Rapamycin; Recklinghausen's disease; Ribosomal Protein S6 Kinases - metabolism; Signal Transduction - drug effects; Sirolimus - pharmacology; Targeted cancer therapy; TOR protein; TOR Serine-Threonine Kinases; Tumor Burden - drug effects; Tumor microenvironment; Tumors; Vascular endothelial growth factor; Vascular Endothelial Growth Factor A - metabolism; Xenograft Model Antitumor Assays; Xenografts; Young Adult
• ISSN: 0020-7136; 1097-0215
• DOI: 10.1002/ijc.24783

Neurofibromatosis type 1 (NF1) patients are prone to the development of malignant tumors, the most common being Malignant Peripheral Nerve Sheath Tumor (MPNST). NF1‐MPNST patients have an overall poor survival due to systemic metastasis. Currently, the management of MPNSTs includes surgery and radiation; however, conventional chemotherapy is not very effective, underscoring the need for effective biologically‐targeted therapies. Recently, the NF1 gene product, neurofibromin, was shown to negatively regulate the phosphoinositide‐3‐kinase (PI3K)/Protein Kinase‐B (Akt)/mammalian Target Of Rapamycin (mTOR) pathway, with loss of neurofibromin expression in established human MPNST cell lines associated with high levels of mTOR activity. We developed and characterized a human NF1‐MPNST explant grown subcutaneously in NOD‐SCID mice, to evaluate the effect of the mTOR inhibitor rapamycin. We demonstrate that rapamycin significantly inhibited human NF1‐MPNST mTOR pathway activation and explant growth in vivo at doses as low as 1.0 mg/kg/day, without systemic toxicities. While rapamycin was effective at reducing NF1‐MPNST proliferation and angiogenesis, with decreased CyclinD1 and VEGF respectively, there was no increase in tumor apoptosis. Rapamycin effectively decreased activation of S6 downstream of mTOR, but there was accompanied increased Akt activation. This study demonstrates the therapeutic potential and limitations of rapamycin in NF1‐associated, and likely sporadic, MPNSTs.