Doxorubicin Impairs Smooth Muscle Cell Contraction: Novel Insights in Vascular Toxicity.

Clinical and animal studies have demonstrated that chemotherapeutic doxorubicin (DOX) increases arterial stiffness, a predictor of cardiovascular risk. Despite consensus about DOX-impaired endothelium-dependent vasodilation as a contributing mechanism, some studies have reported conflicting results on vascular smooth muscle cell (VSMC) function after DOX treatment. The present study aimed to investigate the effects of DOX on VSMC function. To this end, mice received a single injection of 4 mg DOX/kg, or mouse aortic segments were treated ex vivo with 1 µM DOX, followed by vascular reactivity evaluation 16 h later. Phenylephrine (PE)-induced VSMC contraction was decreased after DOX treatment. DOX did not affect the transient PE contraction dependent on Ca2+ release from the sarcoplasmic reticulum (0 mM Ca2+), but it reduced the subsequent tonic phase characterised by Ca2+ influx. These findings were supported by similar angiotensin II and attenuated endothelin-1 contractions. The involvement of voltage-gated Ca2+ channels in DOX-decreased contraction was excluded by using levcromakalim and diltiazem in PE-induced contraction and corroborated by similar K+ and serotonin contractions. Despite the evaluation of multiple blockers of transient receptor potential channels, the exact mechanism for DOX-decreased VSMC contraction remains elusive. Surprisingly, DOX reduced ex vivo but not in vivo arterial stiffness, highlighting the importance of appropriate timing for evaluating arterial stiffness in DOX-treated patients.

Short-Term Proteasome Inhibition: Assessment of the Effects of Carfilzomib and Bortezomib on Cardiac Function, Arterial Stiffness, and Vascular Reactivity.

Proteasome inhibitors such as bortezomib and carfilzomib induce apoptosis and are a cornerstone in the treatment of relapsed or refractory multiple myeloma. However, concerns have emerged concerning their link to cancer therapy-related cardiovascular dysfunction (CTRCD). Bortezomib, a reversible first-generation inhibitor, and carfilzomib, a second-generation irreversible inhibitor, are associated with hypertension, heart failure, and cardiac arrhythmias. The current study investigated the effects of bortezomib and carfilzomib on cardiac (left ventricular ejection fraction, LVEF) and vascular (arterial stiffness, vascular reactivity) function. Cardiac function assessment aimed to build upon existing evidence of proteasome inhibitors CTRCD, while arterial stiffness served as an early indicator of potential vascular remodeling. Groups of 12-week-old C57BL/6J male mice (n = 8 per group) were randomly assigned to receive vehicle, carfilzomib (8 mg/kg I.P.), or bortezomib (0.5 mg/kg I.P.). Additionally, proteasome inhibition was assessed in mice treated with L-NAME (0.5 mg/kg) to induce hypertension. Cardiac and vascular parameters were evaluated via echocardiography on days 0 and 3. On day 6, mice were sacrificed for ex vivo analysis of arterial stiffness and vascular reactivity. Overall, no changes in arterial stiffness were detected either in vivo or ex vivo at basal pressures. However, a steeper pressure-stiffness curve was observed for carfilzomib in normotensive (p < 0.01) and hypertensive (p < 0.0001) mice ex vivo. Additionally, in hypertensive mice, carfilzomib decreased LVEF (p = 0.06), with bortezomib exhibiting similar trends. Vascular reactivity remained largely unchanged, but proteasome inhibition tended to enhance endothelial-independent relaxations in both control and hypertensive mice. In conclusion, short-term treatment with carfilzomib and bortezomib is considered relatively safe for the protocols assessed in the study.

Improved on-tissue detection of the anti-cancer agent doxorubicin by quantitative matrix-assisted laser desorption/ionization mass spectrometry imaging.

Doxorubicin (dox) is an affordable, and highly effective chemotherapeutic agent used in cancer treatment, yet its application is known to cause cumulative cardiac and renal toxicity. In this study, we employed matrix-assisted laser desorption/ionization-mass spectrometry imaging (MALDI-MSI) to evaluate the distribution of dox in mouse heart and kidney after in vivo treatment. To this end, we performed absolute quantification using an isotopically labeled form (13C d3-dox) as an internal standard. Unfortunately, ion suppression often leads to loss of sensitivity in compound detection and can result in hampered drug quantification. To overcome this issue, we developed an on-tissue chemical derivatization (OTCD) method using Girard's reagent T (GirT). With the developed method, dox signal was increased by two orders of magnitude. This optimized sample preparation enabled a sensible gain in dox detection, making it possible to study its distribution and abundance (up to 0.11 pmol/mm2 in the heart and 0.33 pmol/mm2 in the kidney medulla). The optimized approach for on-tissue derivatization and subsequent quantification creates a powerful tool to better understand the relationship between dox exposure (at clinically relevant concentrations) and its biological detrimental effects in various tissues. Overall, this work is a showcase of the added value of MALDI-MSI for pharmaceutical studies to better understand heterogeneity in drug exposure between and within organs.

Dexrazoxane prevents vascular toxicity in doxorubicin-treated mice.

BACKGROUND: Doxorubicin (DOX) is used for breast cancer and lymphoma, but can cause cardiotoxicity, arterial stiffness, and endothelial dysfunction. We recently reported SERPINA3N as biomarker of cardiovascular toxicity in patients and mice. Dexrazoxane (DEXRA) is an FDA-approved drug that prevents DOX-induced cardiac toxicity in high-risk patients. However, the effect of DEXRA on vascular dysfunction during DOX treatment has not been documented. Therefore, here we investigated whether DEXRA protects against DOX-induced arterial stiffness, endothelial dysfunction, and SERPINA3N upregulation in tissue and plasma from mice. METHODS: Male C57BL6/J mice were treated with DOX (4 mg/kg), DEXRA (40 mg/kg), a combination (DEXRA + DOX), or VEHICLE (0.9% NaCl) weekly i.p. for 6 weeks (n = 8 per group). Cardiovascular function was measured in vivo by ultrasound imaging at baseline, weeks 2 and 6. Vascular reactivity was analyzed ex vivo in the thoracic aorta at week 6 and molecular analysis was performed. RESULTS: DEXRA prevented left ventricular ejection fraction decline by DOX (DEXRA + DOX: 62 ± 2% vs DOX: 51 ± 2%). Moreover, DEXRA prevented the increase in pulse wave velocity by DOX (DEXRA + DOX: 2.1 ± 0.2 m/s vs DOX: 4.5 ± 0.3 m/s) and preserved endothelium-dependent relaxation (DEXRA + DOX: 82 ± 3% vs DOX: 62 ± 3%). In contrast to DOX-treated mice, SERPINA3N did not increase in the DEXRA + DOX group. CONCLUSION: Our results not only confirm the cardioprotective effects of DEXRA against DOX-induced cardiotoxicity but also add preservation of vascular endothelial cell function as an important mechanism. Moreover, the study demonstrates the potential of SERPINA3N as a biomarker for monitoring cardiovascular complications of DOX in high-risk patients.

Characterization of systolic and diastolic function, alongside proteomic profiling, in doxorubicin-induced cardiovascular toxicity in mice.

BACKGROUND: The anthracycline doxorubicin (DOX) is a highly effective anticancer agent, especially in breast cancer and lymphoma. However, DOX can cause cancer therapy-related cardiovascular toxicity (CTR-CVT) in patients during treatment and in survivors. Current diagnostic criteria for CTR-CVT focus mainly on left ventricular systolic dysfunction, but a certain level of damage is required before it can be detected. As diastolic dysfunction often precedes systolic dysfunction, the current study aimed to identify functional and molecular markers of DOX-induced CTR-CVT with a focus on diastolic dysfunction. METHODS: Male C57BL/6J mice were treated with saline or DOX (4 mg/kg, weekly i.p. injection) for 2 and 6 weeks (respectively cumulative dose of 8 and 24 mg/kg) (n = 8 per group at each time point). Cardiovascular function was longitudinally investigated using echocardiography and invasive left ventricular pressure measurements. Subsequently, at both timepoints, myocardial tissue was obtained for proteomics (liquid-chromatography with mass-spectrometry). A cohort of patients with CTR-CVT was used to complement the pre-clinical findings. RESULTS: DOX-induced a reduction in left ventricular ejection fraction from 72 ± 2% to 55 ± 1% after 2 weeks (cumulative 8 mg/kg DOX). Diastolic dysfunction was demonstrated as prolonged relaxation (increased tau) and heart failure was evident from pulmonary edema after 6 weeks (cumulative 24 mg/kg DOX). Myocardial proteomic analysis revealed an increased expression of 12 proteins at week 6, with notable upregulation of SERPINA3N in the DOX-treated animals. The human ortholog SERPINA3 has previously been suggested as a marker in CTR-CVT. Upregulation of SERPINA3N was confirmed by western blot, immunohistochemistry, and qPCR in murine hearts. Thereby, SERPINA3N was most abundant in the endothelial cells. In patients, circulating SERPINA3 was increased in plasma of CTR-CVT patients but not in cardiac biopsies. CONCLUSION: We showed that mice develop heart failure with impaired systolic and diastolic function as result of DOX treatment. Additionally, we could identify increased SERPINA3 levels in the mice as well as patients with DOX-induced CVT and demonstrated expression of SERPINA3 in the heart itself, suggesting that SERPINA3 could serve as a novel biomarker.

Dexrazoxane does not mitigate early vascular toxicity induced by doxorubicin in mice.

Apart from cardiotoxicity, the chemotherapeutic agent doxorubicin (DOX) provokes acute and long-term vascular toxicity. Dexrazoxane (DEXRA) is an effective drug for treatment of DOX-induced cardiotoxicity, yet it remains currently unknown whether DEXRA prevents vascular toxicity associated with DOX. Accordingly, the present study aimed to evaluate the protective potential of DEXRA against DOX-related vascular toxicity in a previously-established in vivo and ex vivo model of vascular dysfunction induced by 16 hour (h) DOX exposure. Vascular function was evaluated in the thoracic aorta in organ baths, 16h after administration of DOX (4 mg/kg) or DOX with DEXRA (40 mg/kg) to male C57BL6/J mice. In parallel, vascular reactivity was evaluated after ex vivo incubation (16h) of murine aortic segments with DOX (1 µM) or DOX with DEXRA (10 µM). In both in vivo and ex vivo experiments, DOX impaired acetylcholine-stimulated endothelium-dependent vasodilation. In the ex vivo setting, DOX additionally attenuated phenylephrine-elicited vascular smooth muscle cell (VSMC) contraction. Importantly, DEXRA failed to prevent DOX-induced endothelial dysfunction and hypocontraction. Furthermore, RT-qPCR and Western blotting showed that DOX decreased the protein levels of topoisomerase-IIß (TOP-IIß), a key target of DEXRA, in the heart, but not in the aorta. Additionally, the effect of N-acetylcysteine (NAC, 10 µM), a reactive oxygen species (ROS) scavenger, was evaluated ex vivo. NAC did not prevent DOX-induced impairment of acetylcholine-stimulated vasodilation. In conclusion, our results show that DEXRA fails to prevent vascular toxicity resulting from 16h DOX treatment. This may relate to DOX provoking vascular toxicity in a ROS- and TOP-IIß-independent way, at least in the evaluated acute setting. However, it is important to mention that these findings only apply to the acute (16h) treatment period, and further research is warranted to delineate the therapeutic potential of DEXRA against vascular toxicity associated with longer-term repetitive DOX dosing.