Dual modulation of MCL-1 and mTOR determines the response to sunitinib
Mohamed Elgendy, … , Giuseppe Renne, Saverio Minucci
Mohamed Elgendy, … , Giuseppe Renne, Saverio Minucci
Published November 28, 2016
Citation Information: J Clin Invest. 2017;127(1):153-168. https://doi.org/10.1172/JCI84386.
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Research Article Cell biology Oncology

Dual modulation of MCL-1 and mTOR determines the response to sunitinib

Abstract

Most patients who initially respond to treatment with the multi–tyrosine kinase inhibitor sunitinib eventually relapse. Therefore, developing a deeper understanding of the contribution of sunitinib’s numerous targets to the clinical response or to resistance is crucial. Here, we have shown that cancer cells respond to clinically relevant doses of sunitinib by enhancing the stability of the antiapoptotic protein MCL-1 and inducing mTORC1 signaling, thus evoking little cytotoxicity. Inhibition of MCL-1 or mTORC1 signaling sensitized cells to clinically relevant doses of sunitinib in vitro and was synergistic with sunitinib in impairing tumor growth in vivo, indicating that these responses are triggered as prosurvival mechanisms that enable cells to tolerate the cytotoxic effects of sunitinib. Furthermore, higher doses of sunitinib were cytotoxic, triggered a decline in MCL-1 levels, and inhibited mTORC1 signaling. Mechanistically, we determined that sunitinib modulates MCL-1 stability by affecting its proteasomal degradation. Dual modulation of MCL-1 stability at different dose ranges of sunitinib was due to differential effects on ERK and GSK3β activity, and the latter also accounted for dual modulation of mTORC1 activity. Finally, comparison of patient samples prior to and following sunitinib treatment suggested that increases in MCL-1 levels and mTORC1 activity correlate with resistance to sunitinib in patients.

Authors

Mohamed Elgendy, Amal Kamal Abdel-Aziz, Salvatore Lorenzo Renne, Viviana Bornaghi, Giuseppe Procopio, Maurizio Colecchia, Ravindran Kanesvaran, Chee Keong Toh, Daniela Bossi, Isabella Pallavicini, Jose Luis Perez-Gracia, Maria Dolores Lozano, Valeria Giandomenico, Ciro Mercurio, Luisa Lanfrancone, Nicola Fazio, Franco Nole, Bin Tean Teh, Giuseppe Renne, Saverio Minucci

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Figure 8

Dual modulation of GSK3β phosphorylation contributes to modulation of MCL-1 phosphorylation and levels and mTOR activity in response to sunitinib.

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Dual modulation of GSK3β phosphorylation contributes to modulation of MC...
(A and B) Immunoblotting analysis of MCL-1 levels and mTOR signaling activity in HCT116 cells transfected with the indicated shRNAs (A) or pretreated for 1 hour with GSK3β inhibitor xii (20 μM) or GSK3β inhibitor viii (25 μM) (B) followed by treatment with either DMSO or 10 μM sunitinib for 24 hours. (C) Immunoblotting analysis with the indicated antibodies of lysates prepared from HCT116 cells transfected with the indicated constructs and treated with 1.25 μM sunitinib for 24 hours. (D and E) Percentage of cell death of U2OS, Bon-I, and HCT116 cells transfected with the indicated shRNAs (D) or pretreated for 1 hour with GSK3β inhibitor xii (20 μM) or GSK3β inhibitor viii (20 μM) (E), followed by treatment with either DMSO or sunitinib at 1 μM (U2OS), 5 μM (Bon-I), or 10 μM (HCT116) for 24 hours. (F) Percentage of cell death of U2OS, Bon-I, and HCT116 cells transduced with the indicated constructs and treated with either DMSO or sunitinib at 0.0625 μM (U2OS), 0.125 μM (Bon-I), or 1.25 μM (HCT116) for 24 hours. (G and I) Immunoblotting analysis with the indicated antibodies of lysates prepared from MCL1 KO HCT116 cells transduced with the indicated constructs and treated for 24 hours with either DMSO or 10 μM (G) or 1.25 μM (I) sunitinib. (H and J) Percentage of cell death of MCL1 KO HCT116 cells transduced with the indicated constructs and treated for 24 hours with either DMSO or the indicated concentrations of sunitinib. Results are representative of 3 independent experiments. Error bars indicate SEM. Blots presented are derived from replicate samples run on parallel gels and controlled for even loading.