Potential Therapeutic Strategies for Hypertension-Exacerbated Cardiotoxicity of Anticancer Drugs. Oxid Med Cell Longev. 2016;2016:8139861. [PMID: 27829985 PMCID: PMC5086499 DOI: 10.1155/2016/8139861]

Hypertension in Wilms tumor

Wilms tumor (WT) represents over 90% of all pediatric kidney tumors. Children with WT often present acutely with hypertension which resolves in the short term after nephrectomy. However, WT survivors have increased long-term risk of hypertension, primarily due to decreased nephron mass after nephrectomy, with additional insults from possible exposure to abdominal radiation and nephrotoxic therapies. The diagnosis of hypertension may be improved by ambulatory blood pressure monitoring (ABPM), as several recent single-center studies have shown a substantial proportion of WT survivors with masked hypertension. Current gaps in knowledge include determining which WT patients may benefit from routine screening with ABPM, correlation of casual and ABPM parameters with cardiac abnormalities, and longitudinal assessment of cardiovascular and kidney parameters in relation to appropriate treatment of hypertension. This review aims to summarize the most recent literature on hypertension presentation and management at the time of WT diagnosis as well as the long-term hypertension risk and impact on kidney and cardiovascular outcomes in WT survivors.

Cardiovascular toxicities after anthracycline and VEGF-targeted therapies in adolescent and young adult cancer survivors

BACKGROUND

Cancer survival rates have been steadily improving in the adolescent and young adult (AYA) population, but survivors are at increased risk for cardiovascular disease (CVD). The cardiotoxic effects of anthracycline therapy have been well studied. However, the cardiovascular toxicity associated with newer therapies, such as the vascular endothelial growth factor (VEGF) inhibitors, is less well understood.

OBJECTIVE

This retrospective study of AYA cancer survivors sought to gain insight into their burden of cardiovascular toxicities (CT) following initiation of anthracycline and/or VEGF inhibitor therapy.

METHODS

Data were extracted from electronic medical records over a fourteen-year period at a single institution. Cox proportional hazards regression modeling was used to examine risk factors for CT within each treatment group. Cumulative incidence was calculated with death as a competing risk.

RESULTS

Of the 1,165 AYA cancer survivors examined, 32%, 22%, and 34% of patients treated with anthracycline, VEGF inhibitor, or both, developed CT. Hypertension was the most common outcome reported. Males were at increased risk for CT following anthracycline therapy (HR: 1.34, 95% CI 1.04-1.73). The cumulative incidence of CT was highest in patients who received both anthracycline and VEGF inhibitor (50% at ten years of follow up).

CONCLUSIONS

CT was common among AYA cancer survivors who received anthracycline and/or VEGF inhibitor therapy. Male sex was an independent risk factor for CT following anthracycline treatment. Further screening and surveillance are warranted to continue understanding the burden of CVD following VEGF inhibitor therapy.

Anthracycline-Induced Cardiotoxicity in Breast Cancer Patients: A Five-Year Retrospective Study in 10 Centers

Background

Cardiotoxicity as a result of anthracycline chemotherapy has been linked to increased morbidity and mortality in breast cancer patients. There is a need for early detection through risk factor identification. To date, no large multicenter study has been conducted to describe the incidence, risk factors and clinical and demographic profiles of breast cancer patients with anthracycline-induced cardiotoxicity (AIC) in the Philippines.

Methods

This was a nationwide multicenter retrospective cohort study among adult breast cancer patients who underwent anthracycline chemotherapy from 2015 to 2020 in 10 sites in the Philippines. Baseline characteristics and possible risk factors for AIC were retrieved from medical records and cancer registries. AIC was defined as a reduction of left ventricular ejection fraction (LVEF) by > 10% from baseline to a value of < 53% or the development of overt left ventricular systolic dysfunction or heart failure (HF). Odds ratios from logistic regression were computed to determine risk factors associated with AIC using STATA-15.0 software.

Results

Out of 341 patients included, 33 had AIC, accounting for an incidence of 9.68%. Nine patients (2.6%) had clinical HF. AIC patients had a mean age of 53.91 ± 10.84 years. Breast cancer AIC patients were significantly older and had lower body mass index (BMI) than those without AIC. AIC patients had significantly more comorbidities, especially hypertension and atrial fibrillation. Multivariate analysis showed that patients with any preexisting comorbidity are approximately 12.37 times as likely to have AIC, while those with concurrent chemotherapy are 0.07 times or 93% less likely to have AIC.

Conclusion

Among adult breast cancer patients undergoing anthracycline chemotherapy, we determined a high incidence of cardiotoxicity at 9.68%. Having preexisting comorbidities gave patients 12 times increased odds of developing anthracycline cardiotoxicity. The presence of concurrent non-anthracycline chemotherapy showed an inverse association with the development of AIC which we attribute largely to patient selection in a retrospective study. The significantly higher propensity for AIC development in patients with preexisting comorbidities may warrant closer monitoring and control of patient comorbidities such as hypertension among patients undergoing anthracycline chemotherapy.

Baseline blood pressure and development of cardiotoxicity in patients treated with anthracyclines: A systematic review

Aims

Anthracyclines, a mainstay of cancer treatment, are associated with significant life-threatening cardiotoxicity. As cancer survivorship improves, there is a growing need to identify patients most at risk and strategies to mitigate anthracycline-associated cardiotoxicity. Elevated baseline blood pressure (bBP) is a possible risk factor for cardiotoxicity. The aim of this systematic review was to summarise the literature and evaluate relationships between bBP and anthracycline-associated cardiotoxicity.

Methods and results

Systematic searches were conducted, limited to English language but without restrictions on study type or country of origin. All studies fulfilled the PRISMA statement and relevant studies reviewed and narratively synthesised. A total of 1330 papers were screened, with 12 included in the qualitative synthesis. Eight papers indicated elevated bBP was associated with significantly higher risk of developing cardiotoxicity. Four papers noted significant relationships between left ventricular ejection fraction (LVEF) decline and elevated bBP. Of the four papers that failed to show an association, one noted increased risk of developing chronic heart failure. A relationship between baseline diastolic and systolic BP and anthracycline-associated cardiotoxicity is also noted.

Conclusions

This study indicates adult patients with elevated bBP have increased vulnerability to anthracycline-associated cardiotoxicity, with those with pre-hypertension or raised systolic versus diastolic pressure potentially an overlooked population. Recommendations for inclusion of bBP, incorporating individual systolic versus diastolic pressures, in cardio-oncology risk prediction models to guide clinical decision-making are thus warranted.

Assessment of Oncology Provider Knowledge and Cardiovascular Screening Practices: A Call for Heightened Screening

Cardiac risk factors are known to compound the development of cardiotoxicities (CTx) in patients exposed to anthracycline (ANT) chemotherapy agents. National oncology and cardiology organizations have published recommendations for cardiovascular risk stratification and screening cancer patients following exposure to ANTs. The frequency with which oncology providers are integrating these principles into practice is unknown. This knowledge-based quality improvement (QI) project was designed to heighten oncology provider competencies such that screening frequency of cancer patients for CTx in the post-ANT setting aligns more closely with national guidelines for care. A web-based educational intervention, cardiac screening tool, and evidence-based literature were shared with 20 oncology providers over the course of 5 months. Retrospective chart reviews and pre- and post-project surveys were performed to assess competencies and practice trends. Qualitative and quantitative data were analyzed to illustrate whether the interventions improved knowledge and changed practice. Findings revealed an increase in the number of provider-perceived percentage of high cardiac risk patients and the number of patients screened, knowledge did not improve, and the frequency by which oncology providers ordered echocardiograms increased minimally. Factors such as organizational system changes, time constraints, and change fatigue limited effective and consistent implementation of the project interventions. The trajectory of cancer survivorship is affected by cardiovascular disease. Cardiac screening of cancer patients is a critical component of cancer care that has the potential to positively impact economic and health outcomes of this susceptible population.

Risk Factors for Anthracycline-Induced Cardiotoxicity

Background: Several cardiovascular risk factors have been suggested to be associated with anthracycline-induced cardiotoxicity, but their quantitative effects have not reached a consensus.

Methods: We searched PubMed, EMBASE, and Cochrane Library databases for manuscripts published from inception to February 2021, which reported the results of cardiotoxicity due to anthracycline chemotherapy without trastuzumab. Cardiotoxicity defined by any reduction of left ventricular eject fraction (LVEF) to below 50% or a >10% reduction from baseline was defined as the primary endpoint. Odd ratios (OR) with 95% confidence intervals (CI) were calculated using a random-effects model meta-analysis.

Results: A total of 7,488 patients receiving anthracycline chemotherapy without trastuzumab were included, who had at least one risk factor at baseline. Hypertension (OR: 1.99; 95% CI: 1.43–2.76), diabetes mellitus (OR: 1.74; 95% CI: 1.11–2.74), and obesity (OR: 1.72; 95% CI: 1.13–2.61) were associated with increased risk of cardiotoxicity. In addition, the relative reduction of global longitudinal strain (GLS) from baseline after anthracycline treatment could significantly improve the detection ability of cardiotoxicity (28.5%, 95% CI: 22.1–35.8% vs. 16.4%, 95% CI: 13.4–19.9%) compared with LVEF. The early detection rate of anthracycline-induced cardiotoxicity (3 months after chemotherapy) by GLS was 30.2% (95% CI: 24.9–36.1%), which is similar with the overall result of GLS.

Conclusions: Hypertension, diabetes mellitus, and obesity are associated with increased risk of anthracycline-induced cardiotoxicity, which indicates that corresponding protective strategies should be used during and after anthracycline treatment. The findings of higher detection rate and better early detection ability for cardiotoxicity than LVEF added new proofs for the advantages of GLS in detection of AIC.

The diuretic amiloride attenuates doxorubicin-induced chemobrain in rats: Behavioral and mechanistic study

Cognitive impairment or "chemobrain" is a troublesome adverse effect which had been increasingly reported by cancer patients after doxorubicin (DOX) chemotherapy. Notably, Hypertension, a very common comorbidity in cancer patients, could pose a greater risk for negative cognitive outcomes. Amiloride (AML) is an antihypertensive, potassium-sparing diuretic that has been proven to be neuroprotective in different experimental models; this can be attributed to its ability to inhibit different ion transporters such as Na^+/H⁺ exchanger (NHE), which upon excessive activation can result in intracellular cationic overload, followed by oxidative damage and cellular death. Accordingly, this study was designed to investigate the potential neuroprotective effect of AML against DOX-induced chemobrain and to elucidate possible underlying mechanisms. Briefly, Histopathological examination and neurobehavioral testing (Morris water maze, Y maze and passive avoidance test) showed that AML co-treatment (10 mg/kg/day) markedly attenuated DOX (2 mg/kg/week)-induced neurodegeneration and memory impairment after 4 weeks of treatments. We found that DOX administration up-regulated NHE expression and increased lactic acid content in the hippocampus which were markedly opposed by AML. Moreover, AML mitigated DOX-induced neuroinflammation and decreased hippocampal tumor necrosis factor-α level, nuclear factor kappa-B, and cyclooxygenase-2 expression. Additionally, AML counteracted DOX-induced hippocampal oxidative stress as indicated by normalized malondialdehyde and glutathione levels. Furthermore, AML halted DOX-induced hippocampal apoptosis as evidenced by decreased caspase-3 activity and lower cytochrome c immunoexpression. Our results in addition to the previously reported antitumor effects of AML and its ability to mitigate cancer resistance to DOX therapy could point toward possible new repositioning scenarios of the diuretic AML especially regarding hypertensive cancer patients.

Updates on Anticancer Therapy-Mediated Vascular Toxicity and New Horizons in Therapeutic Strategies

Vascular toxicity is a frequent adverse effect of current anticancer chemotherapies and often results from endothelial dysfunction. Vascular endothelial growth factor inhibitors (VEGFi), anthracyclines, plant alkaloids, alkylating agents, antimetabolites, and radiation therapy evoke vascular toxicity. These anticancer treatments not only affect tumor vascularization in a beneficial manner, they also damage ECs in the heart. Cardiac ECs have a vital role in cardiovascular functions including hemostasis, inflammatory and coagulation responses, vasculogenesis, and angiogenesis. EC damage can be resulted from capturing angiogenic factors, inhibiting EC proliferation, survival and signal transduction, or altering vascular tone. EC dysfunction accounts for the pathogenesis of myocardial infarction, atherothrombosis, microangiopathies, and hypertension. In this review, we provide a comprehensive overview of the effects of chemotherapeutic agents on vascular toxicity leading to hypertension, microvascular rarefaction thrombosis and atherosclerosis, and affecting drug delivery. We also describe the potential therapeutic approaches such as vascular endothelial growth factor (VEGF)-B and prokineticin receptor-1 agonists to maintain endothelial function during or following treatments with chemotherapeutic agents, without affecting anti-tumor effectiveness.

Unravelling the tangled web of hypertension and cancer

Cardiovascular disease remains the primary cause of mortality globally, being responsible for an estimated 17 million deaths every year. Cancer is the second leading cause of death on a global level with roughly 9 million deaths per year being attributed to neoplasms. The two share multiple common risk factors such as obesity, poor physical exercise, older age, smoking and there exists rare monogenic hypertension syndromes. Hypertension is the most important risk factor for cardiovascular disease and affects more than a billion people worldwide and may also be a risk factor for the development of certain types of cancer (e.g. renal cell carcinoma (RCC)). The interaction space of the two conditions becomes more complicated when the well-described hypertensive effect of certain antineoplastic drugs is considered along with the extensive amount of literature on the association of different classes of antihypertensive drugs with cancer risk/prevention. The cardiovascular risks associated with antineoplastic treatment calls for efficient management of relative adverse events and the development of practical strategies for efficient decision-making in the clinic. Pharmacogenetic interactions between cancer treatment and hypertension-related genes is not to be ruled out, but the evidence is not still ample to be incorporated in clinical practice. Precision Medicine has the potential to bridge the gap of knowledge regarding the full spectrum of interactions between cancer and hypertension (and cardiovascular disease) and provide novel solutions through the emerging field of cardio-oncology. In this review, we aimed to examine the bidirectional associations between cancer and hypertension including pharmacotherapy.

Etiology and management of hypertension in patients with cancer

The pathophysiology of hypertension and cancer are intertwined. Hypertension has been associated with an increased likelihood of developing certain cancers and with higher cancer-related mortality. Moreover, various anticancer therapies have been reported to cause new elevated blood pressure or worsening of previously well-controlled hypertension. Hypertension is a well-established risk factor for the development of cardiovascular disease, which is rapidly emerging as one of the leading causes of death and disability in patients with cancer. In this review, we discuss the relationship between hypertension and cancer and the role that hypertension plays in exacerbating the risk for anthracycline- and trastuzumab-induced cardiomyopathy. We then review the common cancer therapies that have been associated with the development of hypertension, including VEGF inhibitors, small molecule tyrosine kinase inhibitors, proteasome inhibitors, alkylating agents, glucocorticoids, and immunosuppressive agents. When available, we present strategies for blood pressure management for each drug class. Finally, we discuss blood pressure goals for patients with cancer and strategies for assessment and management. It is of utmost importance to maintain optimal blood pressure control in the oncologic patient to reduce the risk of chemotherapy-induced cardiotoxicity and to decrease the risk of long-term cardiovascular disease.

Beetroot as a Potential Functional Food for Cancer Chemoprevention, a Narrative Review

Patients with cancer are prone to several debilitating side effects including fatigue, insomnia, depression and cognitive disturbances. Beetroot (Beta vulgaris L.) as a health promoting functional food may be potentially beneficial in cancer. As a source of polyphenols, flavonoids, dietary nitrates and other useful nutrients, beetroot supplementation may provide a holistic means to prevent cancer and manage undesired effects associated with chemotherapy. The main aim of this narrative review is to discuss beetroot's nutrient composition, current studies on its potential utility in chemoprevention and cancer-related fatigue or treatment-related side effects such as cardiotoxicity. This review aims to provide the current status of knowledge and to identify the related research gaps in this area. The flavonoids and polyphenolic components present in abundance in beetroot support its significant antioxidant and anti-inflammatory capacities. Most in vitro and in vivo studies have shown promising results; however, the molecular mechanisms underlying chemopreventive and chemoprotective effects of beetroot have not been completely elucidated. Although recent clinical trials have shown that beetroot supplementation improves human performance, translational studies on beetroot and its functional benefits in managing fatigue or other symptoms in patients with cancer are still lacking.

Cardiovascular risk management in cancer survivors: Are we doing it right?

Although under-recognized, cancer survivors continue to be at an increased risk of death from cardiovascular complications post-remission or cure. This increased burden of cardiovascular disease results from the interplay of various factors. Adequate cardiovascular risk assessment and timely intervention through a multi-disciplinary approach in these patients plays a pivotal role in the prevention of cardiovascular morbidity and mortality. We discuss the shortcomings of using current risk prediction scores in cancer survivors and provide some insights into cardiovascular risk management relevant for primary care physicians, oncologists, and cardiologists alike.

Impact of Arterial Hypertension on Doxorubicin-Based Chemotherapy-Induced Subclinical Cardiac Damage in Breast Cancer Patients

Advances in oncologic therapies have allowed to achieve better outcomes and longer survival in many patients with breast cancer. Anthracyclines are cytotoxic antibiotics widely used in daily oncology practice. However, anthracyclines cause cardiotoxicity which is a limiting factor of its use. Cumulative dose of anthracyclines is the major cause of induced cardiotoxicity. According to previous clinical trials, the major predisposing high-risk factors for anthracycline-based chemotherapy-induced cardiotoxicity are age, body weight, female gender, radiotherapy, and other diseases such as diabetes and hypertension. Experimental studies in animals confirm that hypertension may be a significant factor predisposing anthracycline-based chemotherapy cardiotoxicity. The main objective of our study was to identify the effect of pre-existing arterial hypertension on the development of subclinical cardiac damage during or after doxorubicin-based chemotherapy in breast cancer patients. The study was performed prospectively between March 2016 and January 2017 in the Hospital of Lithuanian University of Health Sciences Kaunas Clinics Department of Oncology and Department of Cardiology. Data of 73 women with breast cancer treated with doxorubicin-based chemotherapy in outpatient clinic were analyzed. Statistically significant association between pre-existing arterial hypertension and left ventricular systolic dysfunction after completion of chemotherapy was observed (P < 0.004). Our study demonstrated that pre-existing arterial hypertension has a very important role in the development of anthracycline-based chemotherapy-induced cardiotoxicity, despite arterial hypertension control quality. Consequently, further studies evaluating impact of other risk factors and how early and sufficient management of arterial hypertension could influence the development of cardiotoxicity are needed to avoid permanent cardiac damage.

Disruption of endothelial cell intraflagellar transport protein 88 exacerbates doxorubicin-induced cardiotoxicity

AIMS

Doxorubicin (DOX) is a potent anticancer drug with severe dose-dependent cardiotoxicity. To address this issue, previous research primarily focused on DOX-induced toxicity on cardiomyocytes. However, more recent research has looked into the endothelium as a therapeutic target due to the emerging role of endothelial cells in the support of cardiomyocyte survival and function.

MAIN METHODS

We investigated a novel role of endothelial cell (EC) primary cilia in the prevention of DOX-mediated cardiotoxicity. Mice lacking EC primary cilia, via the deletion of EC-specific intraflagellar protein 88 (IFT88) expression, were administered DOX (20 mg/kg i.p.), and assessed for survival, cardiac function, cardiac structure changes, and indices of cardiomyocyte injury.

KEY FINDINGS

DOX-treatment resulted in reduced survival and cardiac function (ejection fraction and fractional shortening) in EC-IFT88^-/- mice vs. their similarly treated wild-type littermates. Cardiomyocyte vacuolization, cardiac fibrosis, and serum CK-MB levels were also increased in DOX-treated mice compared to saline-treated controls. However, these parameters were not significantly different when comparing WT and EC-IFT88^-/- mice after DOX treatment.

SIGNIFICANCE

The loss of EC primary cilia accelerated DOX-mediated mortality and reduced cardiac function, suggesting pathways downstream of ciliary-mediated signal transduction as potential targets to promote EC support of cardiomyocyte function during DOX treatment.

Arterial hypertension in patients under antineoplastic therapy: a systematic review

BACKGROUND

Cardio-oncology aims to mitigate adverse cardiovascular manifestations in cancer survivors, but treatment-induced hypertension or aggravated hypertension has received less attention in these high cardiovascular risk patients.

METHODS

In this systematic review, we searched literature for contemporary data on the prevalence, pathophysiologic mechanisms, treatment implications and preventive strategies of hypertension in patients under antineoplastic therapy.

RESULTS

Several classes of antineoplastic drugs, including mainly vascular endothelial growth factor inhibitors, proteasome inhibitors, cisplatin derivatives, corticosteroids or radiation therapy were consistently associated with increased odds for new-onset hypertension or labile hypertensive status in previous controlled patients. Moreover, hypertension constitutes a major risk factor for chemotherapy-induced cardiotoxicity, which is the most serious cardiovascular adverse effect of antineoplastic therapy. Despite the heterogeneity of pooled studies, the pro-hypertensive profile of examined drug classes could be attributed to common structural and functional disorders. Importantly, certain antihypertensive drugs are considered to be more effective in the management of hypertension in this population and may partially attenuate indirect complications of cancer treatment, such as progressive development of cardiomyopathy and/or cardiovascular death. Nonpharmacological approaches to alleviate hypertension in cancer patients are also described, albeit adjudicated as less effective in general.

CONCLUSION

A growing body of evidence suggests that multiple antineoplastic agents increase the rate of progression of hypertension. Physicians need to balance the life-saving cancer treatment and the inflated risk of adverse cardiovascular events due to suboptimal management of hypertension in order to achieve improved clinical outcomes and sustained survival for their patients.

Cytoprotective Effects of Dinitrosyl Iron Complexes on Viability of Human Fibroblasts and Cardiomyocytes

Nitric oxide (NO) is an important signaling molecule that plays a key role in maintaining vascular homeostasis. Dinitrosyl iron complexes (DNICs) generating NO are widely used to treat cardiovascular diseases. However, the involvement of DNICs in the metabolic processes of the cell, their protective properties in doxorubicin-induced toxicity remain to be clarified. Here, we found that novel class of mononuclear DNICs with functional sulfur-containing ligands enhanced the cell viability of human lung fibroblasts and rat cardiomyocytes. Moreover, DNICs demonstrated remarkable protection against doxorubicin-induced toxicity in fibroblasts and in rat cardiomyocytes (H9c2 cells). Data revealed that the DNICs compounds modulate the mitochondria function by decreasing the mitochondrial membrane potential (ΔΨm). Results of flow cytometry showed that DNICs were not affected the proliferation, growth of fibroblasts. In addition, this study showed that DNICs did not affect glutathione levels and the formation of reactive oxygen species in cells. Moreover, results indicated that DNICs maintained the ATP equilibrium in cells. Taken together, these findings show that DNICs have protective properties in vitro. It was further suggested that DNICs may be uncouplers of oxidative phosphorylation in mitochondria and protective mechanism is mainly provided by the leakage of excess charge through the mitochondrial membrane. It is assumed that the DNICs have the therapeutic potential for treating cardiovascular diseases and for decreasing of chemotherapy-induced cardiotoxicity in cancer survivors.

Case of Anthracycline-induced Cardiogenic Shock: A Call to Optimize Modifiable Cardiac Risk Factors Prior to Chemotherapy

Anthracyclines, including doxorubicin, are an important class of chemotherapeutic agents. Their efficacy, however, is limited by cardiotoxicity. Risk factors for anthracycline-associated cardiotoxicity include dose, treatment-specific risk factors including adjunctive radiotherapy, patient-specific modifiable cardiac risk factors including hypertension, hyperlipidemia, diabetes mellitus, tobacco use and obesity, and patient-specific non-modifiable risk factors such as age. The reduction of treatment-specific factors is not always possible, but treatment and reduction of modifiable risk factors should always be an important aspect of the management plan and may reduce the risk of anthracycline-induced cardiotoxicity. We present the case of a 65-year-old male with multiple modifiable cardiovascular risk factors who developed cardiogenic shock shortly after the administration of combination therapy with anthracyclines for the treatment of Hodgkin's lymphoma.

Doxorubicin-induced cardiotoxicity is suppressed by estrous-staged treatment and exogenous 17β-estradiol in female tumor-bearing spontaneously hypertensive rats

Background

Doxorubicin (DOX), an anthracycline therapeutic, is widely used to treat a variety of cancer types and known to induce cardiomyopathy in a time and dose-dependent manner. Postmenopausal and hypertensive females are two high-risk groups for developing adverse effects following DOX treatment. This may suggest that endogenous reproductive hormones can in part suppress DOX-induced cardiotoxicity. Here, we investigated if the endogenous fluctuations in 17β-estradiol (E2) and progesterone (P4) can in part suppress DOX-induced cardiomyopathy in SST-2 tumor-bearing spontaneously hypersensitive rats (SHRs) and evaluate if exogenous administration of E2 and P4 can suppress DOX-induced cardiotoxicity in tumor-bearing ovariectomized SHRs (ovaSHRs).

Methods

Vaginal cytology was performed on all animals to identify the stage of the estrous cycle. Estrous-staged SHRs received a single injection of saline, DOX, dexrazoxane (DRZ), or DOX combined with DRZ. OvaSHRs were implanted with time-releasing pellets that contained a carrier matrix (control), E2, P4, Tamoxifen (Tam), and combinations of E2 with P4 and Tam. Hormone pellet-implanted ovaSHRs received a single injection of saline or DOX. Cardiac troponin I (cTnI), E2, and P4 serum concentrations were measured before and after treatment in all animals. Cardiac damage and function were further assessed by echocardiography and histopathology. Weight, tumor size, and uterine width were measured for all animals.

Results

In SHRs, estrous-staged DOX treatment altered acute estrous cycling that ultimately resulted in prolonged diestrus. Twelve days after DOX administration, all SHRs had comparable endogenous circulating E2. Thirteen days after DOX treatment, SHRs treated during proestrus had decreased cardiac output and increased cTnI as compared to animals treated during estrus and diestrus. DOX-induced tumor reduction was not affected by estrous-staged treatments. In ovaSHRs, exogenous administration of E2 suppressed DOX-induced cardiotoxicity, while P4-implanted ovaSHRs were partly resistant. However, ovaSHRs treated with E2 and P4 did not have cardioprotection against DOX-induced damage.

Conclusions

This study demonstrates that estrous-staged treatments can alter the extent of cardiac damage caused by DOX in female SHRs. The study also supports that exogenous E2 can suppress DOX-induced myocardial damage in ovaSHRs.

Electronic supplementary material

The online version of this article (10.1186/s13293-018-0183-9) contains supplementary material, which is available to authorized users.