MitoQ Treatment Mitigates Senescence Burden in DOXO-Induced Senescent Endothelial Cells Through Reductions in mtROS and DNA Damage

Abstract

Cardiovascular toxicity is one of the adverse consequences of chemotherapy that limits treatment. Specifically, chemotherapeutics such as doxorubicin (DOXO) can lead to endothelial dysfunction through the induction of reactive oxygen species (ROS) and mitochondrial ROS (mtROS) production. MtROS are chemically reactive molecules generated as byproducts of oxidative phosphorylation during mitochondrial respiration. DOXO exacerbates its cardiotoxic effects by amplifying mtROS production, leading to an increase in DNA damage and cell senescence, particularly in endothelial cells (ECs). MitoQ is a mitochondria-targeted antioxidant designed to accumulate within the mitochondria and mitigate oxidative damage by neutralizing mtROS. However, whether MitoQ can rescue mtROS-induced DNA damage and senescence remains elusive. Here, we tested the hypothesis that MitoQ will attenuate DOXO-induced mtROS thus blunting DNA damage and subsequent EC senescence. Human umbilical vein endothelial cells (HUVECs) were simultaneously subjected to 24-hour treatments with DOXO (250nM) and MitoQ (250nM). To evaluate the antioxidative effect of the MitoQ, we examined mitochondrial superoxide using MitoSOX. The results demonstrated that DOXO increases mitochondrial superoxide by 40% (Fig1, p=0.019), whereas addition of MitoQ (MitoQ+DOXO) attenuated mitochondrial superoxide significantly compared to the DOXO group (Fig1, p=0.033). Gene expression of senescence markers, p16 and p21, and Senescence Associated Secretory Phenotypes (SASPs) factors were also examined to assess the effect of MitoQ on senescent endothelial cells. p16 was significantly reduced in the MitoQ+DOXO treatment group compared to the DOXO alone (Fig2, p=0.0090). MitoQ+DOXO lowered p21 expression by 35%, although this difference did not reach significance (Fig2, p=0.340). Moreover, MitoQ+DOXO reduced the SASP factors, IL-8, IL-6 and MCP-1, by more than 54% in comparison to the DOXO group (Fig2, all p≤0.027). Senescent endothelial cells were examined for 53BP1, a double-stranded DNA break marker, using an immunofluorescence (IF) assay. MitoQ+DOXO reduced 53BP1 by 32.6% compared to the DOXO-treated group (Fig3, p=0.011). We also assessed cell proliferation using Bromodeoxyuridine (BrdU) assay. In line with other results, the BrdU assay indicates that the proliferative capability of MitoQ+DOXO-treated cells was improved by more than 20% compared to DOXO-induced senescent cells (Fig4, p=0.008). Our findings suggest that MitoQ can mitigate DOXO-induced mtROS, attenuate DNA damage, and ameliorate senescence in endothelial cells. This provides mechanistic insight suggesting that mtROS may be a driver of cellular senescence in ECs via an increase in DNA damage and MitoQ may be an effcacious therapeutic to treat chemotherapy-induced cardiovascular toxicity. Funded in part by awards from National Institutes of Health Awards R01 AG060395, R01 AG048366, T32 HL139451, F31 AG076312, R01 AG077751, R01 AG076748, Nora Eccles Treadwell foundation (NETF), and Veteran's Affairs Merit Review Award I01 BX004492. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.