Identification of markers that functionally define a quiescent multiple myeloma cell sub-population surviving bortezomib treatment

BMC Cancer

Research Article

Kateri Moore¹  Veronica Calvo²  Denis M Schewe²  Alfred Adomako²  Julio A Aguirre-Ghiso³  Ajai Chari⁴  Noa Biran⁴  Keren Osman⁴  Adrienne W Paton⁵  James C Paton⁵ 

[1] Black Family Stem Cell Institute, Mount Sinai School of Medicine, 10029, New York, NY, USA;Division of Hematology and Oncology, Department of Medicine, Mount Sinai School of Medicine, 10029, New York, NY, USA;Division of Hematology and Oncology, Department of Medicine, Mount Sinai School of Medicine, 10029, New York, NY, USA;Department of Otolaryngology, Mount Sinai School of Medicine, 10029, New York, NY, USA;Tisch Cancer Institute, Mount Sinai School of Medicine, 10029, New York, NY, USA;Black Family Stem Cell Institute, Mount Sinai School of Medicine, 10029, New York, NY, USA;Division of Hematology and Oncology, Department of Medicine, Mount Sinai School of Medicine, 10029, New York, NY, USA;Tisch Cancer Institute, Mount Sinai School of Medicine, 10029, New York, NY, USA;Research Centre for Infectious Diseases, School of Molecular and Biomedical Science, University of Adelaide, 5005, Adelaide, Australia;

关键词: Multiple Myeloma;    Bortezomib;    U266 Cell;    Unfold Protein Response;    RPMI8226 Cell;   

DOI  :  10.1186/s12885-015-1460-1

 received in 2014-08-01, accepted in 2015-05-21,  发布年份 2015

来源: Springer

【 摘 要 】

BackgroundThe mechanisms allowing residual multiple myeloma (MM) cells to persist after bortezomib (Bz) treatment remain unclear. We hypothesized that studying the biology of bortezomib-surviving cells may reveal markers to identify these cells and survival signals to target and kill residual MM cells.MethodsWe used H2B-GFP label retention, biochemical tools and in vitro and in vivo experiments to characterize growth arrest and the unfolded protein responses in quiescent Bz-surviving cells. We also tested the effect of a demethylating agent, 5-Azacytidine, on Bz-induced quiescence and whether inhibiting the chaperone GRP78/BiP (henceforth GRP78) with a specific toxin induced apoptosis in Bz-surviving cells. Finally, we used MM patient samples to test whether GRP78 levels might associate with disease progression. Statistical analysis employed t-test and Mann-Whitney tests at a 95% confidence.ResultsWe report that Bz-surviving MM cells in vitro and in vivo enter quiescence characterized by p21CIP1 upregulation. Bz-surviving MM cells also downregulated CDK6, Ki67 and P-Rb. H2B-GFP label retention showed that Bz-surviving MM cells are either slow-cycling or deeply quiescent. The Bz-induced quiescence was stabilized by low dose (500nM) of 5-azacytidine (Aza) pre-treatment, which also potentiated the initial Bz-induced apoptosis. We also found that expression of GRP78, an unfolded protein response (UPR) survival factor, persisted in MM quiescent cells. Importantly, GRP78 downregulation using a specific SubAB bacterial toxin killed Bz-surviving MM cells. Finally, quantification of Grp78high/CD138+ MM cells from patients suggested that high levels correlated with progressive disease.ConclusionsWe conclude that Bz-surviving MM cells display a GRP78HIGH/p21HIGH/CDK6LOW/P-RbLOW profile, and these markers may identify quiescent MM cells capable of fueling recurrences. We further conclude that Aza + Bz treatment of MM may represent a novel strategy to delay recurrences by enhancing Bz-induced apoptosis and quiescence stability.

【 授权许可】

Unknown   
© Adomako et al.; licensee BioMed Central. 2015. This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.