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Med. Sci. 2018, 6(3), 65;

Polyamine Biosynthetic Pathway as a Drug Target for Osteosarcoma Therapy

Department of Pediatrics and Human Development, College of Human Medicine, Michigan State University, 400 Monroe Avenue, NW, Grand Rapids, MI 49503, USA
Helen DeVos Children’s Hospital, Department of Pediatric Hematology Oncology, Grand Rapids, MI 49503, USA
Department of Medical Biology, Amsterdam University Medical Center, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands
Author to whom correspondence should be addressed.
Received: 13 July 2018 / Revised: 9 August 2018 / Accepted: 13 August 2018 / Published: 16 August 2018
(This article belongs to the Special Issue Polyamine Metabolism in Disease and Polyamine-Targeted Therapies)
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Osteosarcoma (OS) is the most common bone tumor in children. Polyamines (PAs) are ubiquitous cations involved in many cell processes including tumor development, invasion and metastasis. In other pediatric cancer models, inhibition of the PA biosynthesis pathway with ornithine decarboxylase (ODC) inhibitor alpha-difluoromethylornithine (DFMO) results in decreased cell proliferation and differentiation. In OS, the PA pathway has not been evaluated. DFMO is an attractive, orally administered drug, is well tolerated, can be given for prolonged periods, and is already used in pediatric patients. Three OS cell lines were used to study the cellular effects of PA inhibition with DFMO: MG-63, U-2 OS and Saos-2. Effects on proliferation were analyzed by cell count, flow cytometry-based cell cycle analysis and RealTime-Glo™ MT Cell Viability assays. Intracellular PA levels were measured with high-performance liquid chromatography (HPLC). Western blot analysis was used to evaluate cell differentiation. DFMO exposure resulted in significantly decreased cell proliferation in all cell lines. After treatment, intracellular spermidine levels were drastically decreased. Cell cycle arrest at G2/M was observed in U-2 OS and Saos-2. Cell differentiation was most prominent in MG-63 and U-2 OS as determined by increases in the terminal differentiation markers osteopontin and collagen 1a1. Cell proliferation continued to be suppressed for several days after removal of DFMO. Based on our findings, DFMO is a promising new adjunct to current osteosarcoma therapy in patients at high risk of relapse, such as those with poor necrosis at resection or those with metastatic or recurrent osteosarcoma. It is a well-tolerated oral drug that is currently in phase II clinical trials in pediatric neuroblastoma patients as a maintenance therapy. The same type of regimen may also improve outcomes in osteosarcoma patients in whom there have been essentially no medical advances in the last 30 years. View Full-Text
Keywords: cell differentiation; DFMO; ornithine decarboxylase; osteosarcoma; polyamines cell differentiation; DFMO; ornithine decarboxylase; osteosarcoma; polyamines

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Weicht, R.R.; Schultz, C.R.; Geerts, D.; Uhl, K.L.; Bachmann, A.S. Polyamine Biosynthetic Pathway as a Drug Target for Osteosarcoma Therapy. Med. Sci. 2018, 6, 65.

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