Ibudilast attenuates doxorubicin‐induced cytotoxicity by suppressing formation of TRPC3 channel and NADPH oxidase 2 protein complexes

Abstract

Background and Purpose Doxorubicin is a highly effective anticancer agent but eventually induces cardiotoxicity associated with increased production of ROS. We previously reported that a pathological protein interaction between TRPC3 channels and NADPH oxidase 2 (Nox2) contributed to doxorubicin‐induced cardiac atrophy in mice. Here we have investigated the effects of ibudilast, a drug already approved for clinical use and known to block doxorubicin‐induced cytotoxicity, on the TRPC3‐Nox2 complex. We specifically sought evidence that this drug attenuated doxorubicin‐induced systemic tissue wasting in mice. Experimental Approach We used the RAW264.7 macrophage cell line to screen 1,271 clinically approved chemical compounds, evaluating functional interactions between TRPC3 channels and Nox2, by measuring Nox2 protein stability and ROS production, with and without exposure to doxorubicin. In male C57BL/6 mice, samples of cardiac and gastrocnemius muscle were taken and analysed with morphometric, immunohistochemical, RT‐PCR and western blot methods. In the passive smoking model, cells were exposed to DMEM containing cigarette sidestream smoke. Key Results Ibudilast, an anti‐asthmatic drug, attenuated ROS‐mediated muscle toxicity induced by doxorubicin treatment or passive smoking, by inhibiting the functional interactions between TRPC3 channels and Nox2, without reducing TRPC3 channel activity. Conclusions and Implications These results indicate a common mechanism underlying induction of systemic tissue wasting by doxorubicin. They also suggest that ibudilast could be repurposed to prevent muscle toxicity caused by anticancer drugs or passive smoking.

Clomipramine suppresses ACE2-mediated SARS-CoV-2 entry

“…As to the possibility of the improvement of severe COVID-19 by clomipramine, we suggest an anti-inflammatory effect of clomipramine like ibudilast 17 . We have previously reported that transient receptor potential canonical (TRPC) 3 protein, a major component of receptor-activated cation channels, contributes to pathological myocardial atrophy caused by anti-cancer drug treatment 16 , by promoting NADPH oxidase (Nox) 2dependent reactive oxygen species (ROS) production on cardiac plasma membrane through interacting with Nox2 and preventing Nox2 from ER-associated degradation 20 .…”

“…In this study, we focused on ACE2 internalization as a therapeutic target of severe COVID-19. Among 13 approved drugs that we have previously identified as potent inhibitor of cardiotoxicity caused by doxorubicin treatment 16,17 , clomipramine, a tricyclic antidepressant 18 , was found to suppress SARS-CoV-2 invasion and infection in TMPRSS2-expressing VeroE6 cells and human iPS-derived cardiomyocytes (iPS-CMs). Clomipramine also synergistically suppresses SARS-CoV-2 virus infection with remdesivir, suggesting the potential as a breakthrough treatment for severe COVID-19.…”

Canonical Transient Receptor Potential Channels and Vascular Smooth Muscle Cell Plasticity

“… 90 We recently screened a potent inhibitor of the TRPC3-Nox2 complex using a library of already approved drugs and found that ibudilast, a PDE4 inhibitor approved for the treatment of asthma and dizziness secondary to chronic cerebral circulation impairment associated with the sequelae of cerebral infarction, significantly suppressed doxorubicin-induced atrophic shrinkage of cardiomyocytes and skeletal muscles, as well as macrophage cell death. 97 98 However, our preliminary experiments indicate that TRPC3 selective inhibitors have little impact on VSMC plasticity or vascular diseases, including peripheral arterial disease. This may be because TRPC6 is highly expressed in VSMCs and predominantly regulates VSMC plasticity, rather than the TRPC3 channel or the TRPC3-Nox2 protein complex.…”

Untargeted Safety Pharmacology Screen of Blood-Activating and Stasis-Removing Patent Chinese Herbal Medicines Identified Nonherbal Ingredients as a Cause of Organ Damage in Experimental Models

“…Dox is a well-established anticancer drug, but it broad-spectrum cytotoxicity has also been reported (Nishiyama et al, 2019). Using Dox as a cellular toxicity positive control, we determined each of the chemical synthetic drugs in NLTC for the mechanistic insights, such as mitochondrial mass, mitochondrial membrane potential, and intracellular calcium.…”