American Association for Cancer Research
00085472can132159-sup-fig3.pdf (718.31 kB)

Supplementary Figure 3 from Redox Modulation of Adjacent Thiols in VLA-4 by AS101 Converts Myeloid Leukemia Cells from a Drug-Resistant to Drug-Sensitive State

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journal contribution
posted on 2023-03-30, 22:14 authored by Adi Layani-Bazar, Itai Skornick, Alain Berrebi, Maor H. Pauker, Elad Noy, Alon Silberman, Michael Albeck, Dan L. Longo, Yona Kalechman, Benjamin Sredni

PDF file - 718K, Fig. S3: The VLA-4 integrin activity on AML cells can be directly affected by AS101 by redox rearrangements of vicinal thiols within the cysteine-rich domain of the integrin resulting in physiologic consequences.



Interaction between the integrin VLA-4 on acute myelogenous leukemia (AML) cells with stromal fibronectin is a decisive factor in chemotherapeutic resistance. In this study, we provide a rationale for a drug repositioning strategy to blunt integrin activation in AML cells and restore their sensitivity to chemotherapy. Specifically, we demonstrate that the nontoxic tellurium compound AS101, currently being evaluated in clinical trials, can abrogate the acquired resistance of AML. Mechanistic investigations revealed that AS101 caused redox inactivation of adjacent thiols in the exofacial domain of VLA-4 after its ligation to stromal fibronectin. This effect triggered cytoskeletal conformational changes that decreased PI3K/Akt/Bcl2 signaling, an obligatory step in chemosensitization by AS101. In a mouse xenograft of AML derived from patient leukemic cells with high VLA-4 expression and activity, we demonstrated that AS101 abrogated drug resistance and prolonged survival in mice receiving chemotherapy. Decreased integrin activity was confirmed on AML cells in vivo. The chemosensitizing activity of AS101 persisted in hosts with defective adaptive and innate immunity, consistent with evidence that integrin deactivation was not mediated by heightening immune attack. Our findings provide a mechanistic rationale to reposition the experimental clinical agent, AS101, to degrade VLA-4–mediated chemoresistance and improve clinical responses in patients with AML. Cancer Res; 74(11); 3092–103. ©2014 AACR.

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