Inhibition of Neuroblastoma Cell Growth by Difluoromethylornithine (DFMO) and Bortezomib through Suppression of LIN28 and MYCN

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DOI: 10.4236/jct.2017.86048    1,430 Downloads   2,892 Views  Citations

ABSTRACT

Neuroblastoma (NB) is the most common childhood cancer arising from the nervous system. Many high-risk neuroblastoma (HRNB) patients develop relapse after initial response to induction treatment and overall long term survival remains poor (less than 60%), emphasizing the need for new therapeutic approaches and more effective treatments. Combination therapies present a favorable approach to improve efficacy, decrease toxicity, and reduce development of drug resistance. Difluoromethylornithine (DFMO) has shown promise in recent clinical trials as a therapeutic agent in treating HRNB. Proteasomes are known to play an important role in tumor cell growth. Bortezomib was the first proteasome inhibitor shown to have anticancer activity clinically. In this study we explore the mechanistic and therapeutic effects of the novel drug combination of DFMO and bortezomib in NB. Cell proliferation studies demonstrated synergistic inhibition of NB cell growth. Bortezomib induced cleaved caspase-3 apoptotic pathway whereas DFMO induced a cytostatic effect on NB cells. Western blot analyses demonstrated down regulation of MYCN, LIN28 and NF-kB in response to DFMO and bortezomib, pathways that are important in cancer stem cells. A decrease in ATP-per-cell when treated with combination therapy suggests inhibition of glycolytic metabolism in NB cells. DFMO as a single agent or in combination with bortezomib significantly reduced tumor growth in xenograft mice. Given the lack of effective treatments, DFMO coupled with bortezomib offers a potential new therapeutic treatment for children with NB.

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Rich, M. , Zhao, P. , Nagulapally, A. , Bond, J. and Sholler, G. (2017) Inhibition of Neuroblastoma Cell Growth by Difluoromethylornithine (DFMO) and Bortezomib through Suppression of LIN28 and MYCN. Journal of Cancer Therapy, 8, 561-578. doi: 10.4236/jct.2017.86048.

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