Disulfiram (DSF) acts as a copper ionophore to induce copper‐dependent oxidative stress and mediate anti‐tumor efficacy in inflammatory breast cancer

Abstract

Cancer cells often have increased levels of reactive oxygen species (ROS); however, acquisition of redox adaptive mechanisms allows for evasion of ROS-mediated death. Inflammatory breast cancer (IBC) is a distinct, advanced BC subtype characterized by high rates of residual disease and recurrence despite advances in multimodality treatment. Using a cellular model of IBC, we identified an oxidative stress response (OSR) signature in surviving IBC cells after administration of an acute dose of an ROS inducer. Metagene analysis of patient samples revealed significantly higher OSR scores in IBC tumor samples compared to normal or non-IBC tissues, which may contribute to the poor response of IBC tumors to common treatment strategies, which often rely heavily on ROS induction. To combat this adaptation, we utilized a potent redox modulator, the FDA-approved small molecule Disulfiram (DSF), alone and in combination with copper. DSF forms a complex with copper (DSF-Cu) increasing intracellular copper concentration both in vitro and in vivo, bypassing the need for membrane transporters. DSF-Cu antagonized NFκB signaling, aldehyde dehydrogenase activity and antioxidant levels inducing oxidative stress-mediated apoptosis in multiple IBC cellular models. In vivo, DSF-Cu significantly inhibited tumor growth without significant toxicity, causing apoptosis only in tumor cells. These results indicate that IBC tumors are highly redox adapted, which may render them resistant to ROS-inducing therapies. DSF, through redox modulation, may be a useful approach to enhance chemo- and/or radio-sensitivity for advanced BC subtypes where therapeutic resistance is an impediment to durable responses to current standard of care.

Copper as a target for prostate cancer therapeutics: copper-ionophore pharmacology and altering systemic copper distribution

“…We, and others, postulated that endogenous elevated intracellular copper predisposed the cancer cells to sensitivity, by possibly underpinning a heightened state of oxidative stress [8, 14, 17, 23]. However, we recently established that only a small subset of prostate cancer patients' harbour elevated intratumoral copper [26] and thus sought to clarify whether copper is indeed the critical, and targetable, factor.…”

“…Raised intracellular ROS is a well-defined feature of human prostate cancer and clinical studies have unequivocally confirmed a role for oxidative stress in the development and progression of this disease [19–22]. Therefore, it has been postulated that elevated endogenous copper may predispose prostate cancer cells to copper-ionophore sensitivity, by possibly underpinning a heightened state of oxidative stress [8, 14, 17, 23]. However, copper ions can exert toxicity through a myriad of mechanisms, including protein iron-sulfur cluster interference, proteasome inhibition and by displacing functional metals (e.g.…”

Three-dimensional culture systems in cancer research: Focus on tumor spheroid model

“…In matrix-on-top method, cells in single cell suspension are seeded on top of solidified matrix, followed by gentle agitation during incubation at 37°C. The cells spontaneously aggregate to form spheroids while remaining attached to the matrix (Allensworth et al , 2015; Ingeson-carlsson et al , 2015). In matrix embedded technique, cells suspended in liquefied matrix (chilled Matrigel) are dispensed onto the matrix pre-coated well and incubated at 37°C during which cells get embedded within the matrix upon gelation (Lee et al , 2007).…”

Inventions and Innovations in Preclinical Platforms for Cancer Research

“…There are several methods for cell spheroid formation other than the microfluidic approach including magnetic levitation [34], 3D-bioprinting [35], hydrophobic surfaces [36], matrix-on-top [37], matrix-embedded [38], polymeric aqueous two-phase system [39], floating liquid marbles [40], multiwell plates [41], bioreactor flasks [42], liquid overlay [43] and HD techniques [36]. Some of these techniques such as HD and multiwell plates are laborious while some others like 3D-bioprinting and magnetic levitation are costly and still lack the standard protocols.…”