Abstract | PURPOSE: EXPERIMENTAL DESIGN: We tested the efficacy of imatinib or PLX3397 either alone or in combination with TORC1 inhibitor rapamycin in a cell proliferation assay in vitro and by immunoblotting to determine target inhibition. Immunoblotting and immunohistochemical analysis was further carried out using xenograft samples in vivo. RESULTS: Our in vitro studies show that imatinib and PLX3397 similarly inhibit cell growth and this can be enhanced with rapamycin with comparable target specificity. However, in vivo studies clearly demonstrate that compared with imatinib, PLX3397 results in sustained blockade of c-Kit, c-Fms, and PDGFRβ, resulting in significant suppression of tumor growth. Moreover, staining for Iba-1, a marker for macrophages, indicates that PLX3397 results in significant depletion of macrophages in the growing tumors. The combination of PLX3397 and rapamycin results in even greater macrophage depletion with continued growth suppression, even when the drug treatment is discontinued. CONCLUSIONS: Taken together, our data strongly suggest that PLX3397 is superior to imatinib in the treatment of MPNSTs, and the combination of PLX3397 with a TORC1 inhibitor could provide a new therapeutic approach for the treatment of this disease.
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Authors | Parag P Patwardhan, Oliver Surriga, Michael J Beckman, Elisa de Stanchina, Ronald P Dematteo, William D Tap, Gary K Schwartz |
Journal | Clinical cancer research : an official journal of the American Association for Cancer Research
(Clin Cancer Res)
Vol. 20
Issue 12
Pg. 3146-58
(Jun 15 2014)
ISSN: 1557-3265 [Electronic] United States |
PMID | 24718867
(Publication Type: Journal Article, Research Support, N.I.H., Extramural)
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Copyright | ©2014 American Association for Cancer Research. |
Chemical References |
- Aminopyridines
- Benzamides
- Piperazines
- Pyrimidines
- Pyrroles
- pexidartinib
- Imatinib Mesylate
- Proto-Oncogene Proteins c-kit
- Receptor, Platelet-Derived Growth Factor beta
- Sirolimus
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Topics |
- Aminopyridines
(pharmacology)
- Animals
- Antineoplastic Combined Chemotherapy Protocols
(pharmacology)
- Apoptosis
(drug effects)
- Benzamides
(administration & dosage)
- Blotting, Western
- Cell Proliferation
(drug effects)
- Humans
- Imatinib Mesylate
- Macrophages
(drug effects, metabolism, pathology)
- Mice
- Mice, Inbred ICR
- Mice, SCID
- Neurilemmoma
(drug therapy, metabolism, pathology)
- Piperazines
(administration & dosage)
- Proto-Oncogene Proteins c-kit
(antagonists & inhibitors)
- Pyrimidines
(administration & dosage)
- Pyrroles
(pharmacology)
- Receptor, Platelet-Derived Growth Factor beta
(antagonists & inhibitors)
- Sirolimus
(administration & dosage)
- Tumor Cells, Cultured
- Xenograft Model Antitumor Assays
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