TY - JOUR
T1 - Panobinostat and venetoclax enhance the cytotoxicity of gemcitabine, busulfan, and melphalan in multiple myeloma cells
AU - Valdez, Benigno C.
AU - Li, Yang
AU - Murray, David
AU - Liu, Yan
AU - Nieto, Yago
AU - Bashir, Qaiser
AU - Qazilbash, Muzaffar H.
AU - Andersson, Borje S.
N1 - Funding Information:
This study was supported in part by the National Institutes of Health through M. D. Anderson's Cancer Center Support Grant CA016672 (Flow Cytometry & Cellular Imaging Facility) and by the Stephen L. and Lavinia Boyd Fund for Leukemia Research.
Publisher Copyright:
© 2020
PY - 2020/1
Y1 - 2020/1
N2 - Gemcitabine (Gem), busulfan (Bu), and melphalan (Mel) are used for hematopoietic stem cell transplantation. To further improve their efficacy, a preclinical study on their synergism with the histone deacetylase inhibitor panobinostat (Pano) and the BCL2 inhibitor venetoclax/ABT199 was performed. Multiple myeloma cell lines MM.1R and MC/CAR were exposed to ∼IC20 levels of the drugs. Synergistic cytotoxicity was observed in cells exposed to the five-drug combination as indicated by combination indexes <1, supported by ∼86% inhibition of proliferation and ∼84% annexin V positivity in MM.1R and ∼58% inhibition of proliferation and ∼46% annexin V positivity in MC/CAR cells. Activation of the DNA damage response and apoptosis were suggested by a modest increase in the phosphorylation of ATM and its substrates; significant cleavage of PARP1, caspase 3, and heat shock protein 90; DNA fragmentation; mitochondrial membrane depolarization; and reactive oxygen species production. The five-drug combination significantly decreased the levels of PI3K, AKT, mTOR, RAPTOR, P-P70S6K, and eIF2α, with concomitant increases in P-AMPK and its substrate Tuberin/TSC2, suggesting that the mTOR signaling pathway was compromised. Endoplasmic reticulum stress through activation of the unfolded protein response was also observed as suggested by increases in the levels of calnexin, BiP/GRP78, ERO1-Lα, and protein disulfide isomerase, which may relate to venetoclax-mediated inhibition of BCL2 in the endoplasmic reticulum. This is the first report on the effects of a venetoclax-containing regimen on the unfolded protein response. These results provide a rationale to propose a clinical trial on use of Gem + Bu + Mel + Pano + Venetoclax as part of a conditioning regimen for multiple myeloma patients undergoing autologous hematopoietic stem cell transplantation.
AB - Gemcitabine (Gem), busulfan (Bu), and melphalan (Mel) are used for hematopoietic stem cell transplantation. To further improve their efficacy, a preclinical study on their synergism with the histone deacetylase inhibitor panobinostat (Pano) and the BCL2 inhibitor venetoclax/ABT199 was performed. Multiple myeloma cell lines MM.1R and MC/CAR were exposed to ∼IC20 levels of the drugs. Synergistic cytotoxicity was observed in cells exposed to the five-drug combination as indicated by combination indexes <1, supported by ∼86% inhibition of proliferation and ∼84% annexin V positivity in MM.1R and ∼58% inhibition of proliferation and ∼46% annexin V positivity in MC/CAR cells. Activation of the DNA damage response and apoptosis were suggested by a modest increase in the phosphorylation of ATM and its substrates; significant cleavage of PARP1, caspase 3, and heat shock protein 90; DNA fragmentation; mitochondrial membrane depolarization; and reactive oxygen species production. The five-drug combination significantly decreased the levels of PI3K, AKT, mTOR, RAPTOR, P-P70S6K, and eIF2α, with concomitant increases in P-AMPK and its substrate Tuberin/TSC2, suggesting that the mTOR signaling pathway was compromised. Endoplasmic reticulum stress through activation of the unfolded protein response was also observed as suggested by increases in the levels of calnexin, BiP/GRP78, ERO1-Lα, and protein disulfide isomerase, which may relate to venetoclax-mediated inhibition of BCL2 in the endoplasmic reticulum. This is the first report on the effects of a venetoclax-containing regimen on the unfolded protein response. These results provide a rationale to propose a clinical trial on use of Gem + Bu + Mel + Pano + Venetoclax as part of a conditioning regimen for multiple myeloma patients undergoing autologous hematopoietic stem cell transplantation.
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U2 - 10.1016/j.exphem.2020.01.003
DO - 10.1016/j.exphem.2020.01.003
M3 - Article
C2 - 31954171
AN - SCOPUS:85078427343
SN - 0301-472X
VL - 81
SP - 32
EP - 41
JO - Experimental Hematology
JF - Experimental Hematology
ER -