Sirt3 promotes sensitivity to sunitinib-induced cardiotoxicity via inhibition of GTSP1/JNK/autophagy pathway in vivo and in vitro

Betaine alleviates doxorubicin-related cardiotoxicity via suppressing oxidative stress and inflammation via the NLRP3/SIRT1 pathway

Cardiotoxicity is one of the side effects of the anti-cancer drug doxorubicin (DOX) that limits its clinical application. Betaine (BT) is a natural agent with promising useful effects against inflammation and oxidative stress (OS). We assessed the effects of BT on DOX-induced cardiotoxicity in mice. Forty-two male NMRI mice were assigned to six groups: I: control; II: BT (200 mg/kg; orally, alone); III: DOX (2.5 mg/kg; six injections (ip)) for two weeks; IV, V, VI: BT (50 mg/kg, 100 mg/kg, and 200 mg/kg; orally, once a day for two weeks, respectively) plus DOX administration. The cardiac enzymes like cardiac troponin-I (cTn-I), lactate dehydrogenase (LDH), and creatine kinase-MB (CK-MB) were assessed in serum. Oxidative/inflammatory markers like nitric oxide (NO), malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT), reduced glutathione level (GSH), and glutathione peroxidase (GPx) activities were determined in cardiac tissue. The expressions of NOD-like receptor protein 3 (NLRP3), caspase-1, interleukin (IL)-1β, and silent information regulator 1 (SIRT1) proteins were also evaluated in cardiac tissue. The results indicated that DOX significantly increased LDH, CK-MB, cTn-I, MDA, and NO levels and also the caspase-1, NLRP3, and IL-1β expression. Furthermore, DOX caused a significant reduction in the GSH levels and SOD, CAT, GPX activities, and the expression of SIRT1 protein in heart tissue. However, BT significantly improved all studied parameters. The findings were confirmed by histopathological assessments of the heart. BT can protect against DOX-induced cardiotoxicity by suppressing the activation of NLRP3 and OS by stimulating the SIRT1 pathway.

SIRT3 MEDIATES THE CARDIOPROTECTIVE EFFECT OF THERAPEUTIC HYPOTHERMIA AFTER CARDIAC ARREST AND RESUSCITATION BY RESTORING AUTOPHAGIC FLUX VIA THE PI3K/AKT/MTOR PATHWAY

ABSTRACT

Background : Postresuscitation cardiac dysfunction is a significant contributor to early death following cardiopulmonary resuscitation (CPR). Therapeutic hypothermia (TH) mitigates myocardial dysfunction due to cardiac arrest (CA); however, the underlying mechanism remains unclear. Sirtuin 3 (Sirt3) was found to affect autophagic activity in recent research, motivating us to investigate its role in the cardioprotective effects of TH in the treatment of CA. Methods : Sprague-Dawley rats were used to establish an in vivo CA/CPR model and treated with a selective Sirt3 inhibitor or vehicle. Survival rate, myocardial function, autophagic flux, and Sirt3 expression and activity were evaluated. H9C2 cells were subjected to oxygen-glucose deprivation/reoxygenation (OGD/R) injury in vitro . The cells were transfected with Sirt3-siRNA and treated with the autophagy inhibitor chloroquine or the PI3K inhibitor LY294002, and cell viability and autophagic flux were assessed. Results : Rats exhibited decreased survival and impaired cardiac function after CA/CPR, which were alleviated by TH. Mechanistically, TH restored Sirt3 expression and autophagic flux, which were impaired by CA/CPR. Sirt3 inactivation diminished the capacity of TH to restore autophagic flux and partially abolished the improvements in myocardial function and survival. An in vitro study further showed that TH-induced restoration of disrupted autophagic flux by OGD/R was attenuated by pretreatment with Sirt3-siRNA, and this attenuation was partially rescued by the inhibition of PI3K/Akt/mTOR signaling cascades. Conclusions : Sirt3 mediates the cardioprotective effect of TH by restoring autophagic flux via the PI3K/Akt/mTOR pathway. These findings suggest the potential of Sirt3 as a therapeutic target for CA.

Advances in SIRT3 involvement in regulating autophagy-related mechanisms

The silencing regulatory factor 2-like protein 3 (SIRT3) is a nicotinamide adenine dinucleotide (NAD+) dependent deacetylase located primarily in the mitochondria. This protein plays an important role in oxidative stress, energy metabolism, and autophagy in multicellular organisms. Autophagy (macroautophagy) is primarily a cytoprotective mechanism necessary for intracellular homeostasis and the synthesis, degradation, and recycling of cellular products. Autophagy can influence the progression of several neural, cardiac, hepatic, and renal diseases and can also contribute to the development of fibrosis, diabetes, and many types of cancer. Recent studies have shown that SIRT3 has an important role in regulating autophagy. Therefore in this study, we aimed to perform a literature review to summarize the role of SIRT3 in the regulation of cellular autophagy. The findings of this study could be used to identify new drug targets for SIRT3-related diseases. Methods: A comprehensive literature review of the mechanism involved behind SIRT3 and autophagy-related diseases was performed. Relevant literature published in Pubmed and Web of Science up to July 2023 was identified using the keywords "silencing regulatory factor 2-like protein 3", "SIRT3" and "autophagy".

The role and mechanism of epigenetics in anticancer drug-induced cardiotoxicity

Cardiovascular disease is the main factor contributing to the global burden of diseases, and the cardiotoxicity caused by anticancer drugs is an essential component that cannot be ignored. With the development of anticancer drugs, the survival period of cancer patients is prolonged; however, the cardiotoxicity caused by anticancer drugs is becoming increasingly prominent. Currently, cardiovascular disease has emerged as the second leading cause of mortality among long-term cancer survivors. Anticancer drug-induced cardiotoxicity has become a frontier and hot topic. The discovery of epigenetics has given the possibility of environmental changes in gene expression, protein synthesis, and traits. It has been found that epigenetics plays a pivotal role in promoting cardiovascular diseases, such as heart failure, coronary heart disease, and hypertension. In recent years, increasing studies have underscored the crucial roles played by epigenetics in anticancer drug-induced cardiotoxicity. Here, we provide a comprehensive overview of the role and mechanisms of epigenetics in anticancer drug-induced cardiotoxicity.

Sunitinib induces cardiotoxicity through modulating oxidative stress and Nrf2-dependent ferroptosis in vitro and in vivo

SUN, a multi-targeted tyrosine kinase inhibitor, exerts cardiotoxicity which hinders its clinical use. It is necessary to elucidate molecular mechanism of SUN-induced cardiotoxicity. To elucidate molecular mechanism of SUN-induced cardiotoxicity and whether it is related to Nrf2-dependent ferroptosis, in vitro model with H9c2 cells derived from rat heart tissue and in vivo model (C57BL/6J male mouse) were used in the present study. In vivo model was established by oral treatment of SUN at dose of 10, 20, 40 mg/kg for 14 days. Body weight, ECG, plasma enzyme activities, histology staining were performed to evaluate heart function. Western-blot was performed to analyze the level of ferroptosis-related proteins. In vitro results indicated that SUN markedly induced ferroptosis embodied as collapsed MMP, accumulated iron and elevated ROS. In vivo results showed that SUN significantly impaired cardiac function. Abnormal electrocardiogram, increased serum CK and lactate LDH levels were significantly observed in SUN groups. Histology staining showed that SUN caused structural injuries and fibrosis deposition. Moreover, SUN increased the level of MDA and Fe2+ content, decreased the level of GSH. Both in vitro and in vivo experiments indicated that SUN reduced the expression of Nrf2, HO-1, NQO1, GPX4 and FTH1, enhanced the TfR expression. This study suggested that oxidative stress and Nrf2-dependent ferroptosis played a vital role in SUN-induced cardiotoxicity.

SIRT3 regulates mitochondrial function: A promising star target for cardiovascular disease therapy

Dysregulation of mitochondrial homeostasis is common to all types of cardiovascular diseases. SIRT3 regulates apoptosis and autophagy, material and energy metabolism, mitochondrial oxidative stress, inflammation, and fibrosis. As an important mediator and node in the network of mechanisms, SIRT3 is essential to many activities. This review explains how SIRT3 regulates mitochondrial homeostasis and the tricarboxylic acid cycle to treat common cardiovascular diseases. A novel description of the impact of lifestyle factors on SIRT3 expression from the angles of nutrition, exercise, and temperature is provided.

The Current State of Research on Sirtuin-Mediated Autophagy in Cardiovascular Diseases

Sirtuins belong to the class III histone deacetylases and possess nicotinamide adenine dinucleotide-dependent deacetylase activity. They are involved in the regulation of multiple signaling pathways implicated in cardiovascular diseases. Autophagy is a crucial adaptive cellular response to stress stimuli. Mounting evidence suggests a strong correlation between Sirtuins and autophagy, potentially involving cross-regulation and crosstalk. Sirtuin-mediated autophagy plays a crucial regulatory role in some cardiovascular diseases, including atherosclerosis, ischemia/reperfusion injury, hypertension, heart failure, diabetic cardiomyopathy, and drug-induced myocardial damage. In this context, we summarize the research advancements pertaining to various Sirtuins involved in autophagy and the molecular mechanisms regulating autophagy. We also elucidate the biological function of Sirtuins across diverse cardiovascular diseases and further discuss the development of novel drugs that regulate Sirtuin-mediated autophagy.

GSTP1-mediated S-glutathionylation of Pik3r1 is a redox hub that inhibits osteoclastogenesis through regulating autophagic flux

Glutathione S-transferase P1(GSTP1) is known for its transferase and detoxification activity. Based on disease-phenotype genetic associations, we found that GSTP1 might be associated with bone mineral density through Mendelian randomization analysis. Therefore, this study was performed both in vitro cellular and in vivo mouse model to determine how GSTP1 affects bone homeostasis. In our research, GSTP1 was revealed to upregulate the S-glutathionylation level of Pik3r1 through Cys498 and Cys670, thereby decreasing its phosphorylation, further controlling the alteration of autophagic flux via the Pik3r1-AKT-mTOR axis, and lastly altering osteoclast formation in vitro. In addition, knockdown and overexpression of GSTP1 in vivo also altered bone loss outcomes in the OVX mice model. In general, this study identified a new mechanism by which GSTP1 regulates osteoclastogenesis, and it is evident that the cell fate of osteoclasts is controlled by GSTP1-mediated S-glutathionylation via a redox-autophagy cascade.

Guhong injection mitigates myocardial ischemia/reperfusion injury by activating GST P to inhibit ASK1-JNK/p38 pathway

BACKGROUND

Guhong injection (GHI), a novel compound preparation that is composed of a chemical drug, namely aceglutamide, and the aqueous extract of safflower (Carthamus tinctorius L.), exhibits extreme antioxidative, antiapoptotic, anti-inflammatory, and neuroprotective effects. Since oxidative stress, apoptosis, and inflammatory response are all the dominant mechanisms of myocardial ischemia/reperfusion (MI/R) injury, we probe into the protective mechanism of GHI on MI/R injury for the first time.

METHODS

In this research, we first employed molecular docking to determine whether three active ingredients in GHI, acetylglutamine (NAG), hydroxysafflor yellow A (HSYA), and syringin, possessed the potential activity to modulate the protein, glutathione S-transferase P (GST P). We further identified the protective effect of GHI on myocardial tissue with TTC staining, HE staining, TUNEL staining, and ELISA, and on H9c2 with flow cytometry and ELISA. We next explored whether the cardioprotective effect of GHI on left anterior descending ligation-reperfusion in rats and hypoxia/reoxygenation (H/R) in H9c2 cells was related to activate GST P to inhibit ASK1-JNK/p38 pathway via approaches of qRT-PCR and Western blot.

RESULTS

Results of molecular docking indicated that all three compounds spontaneously docked to GST P, among them the binding affinities of both HSYA and syringin to GST P were higher than NAG. In vivo, GHI reduced myocardial infarction size and mitigated myocardial pathological injury. In vitro, GHI enhanced cell viability and extenuated depolarization of mitochondrial membrane potential. In addition, the results of in vivo and in vitro studies demonstrated that the cardioprotection of GHI was associated with improving the mRNA and protein expression levels of GST P to modulate oxidative stress, and inhibiting the levels of mRNA expression and protein phosphorylation of ASK1, JNK, and p38. However, the suppressed effect of GHI on ASK1-JNK/p38 pathway was reversed by ethacrynic acid (EA, a GST inhibitor), indicating that the regulation of GHI on ASK1-JNK/p38 was related to the activity of GST P. Besides, the in vitro results of qRT-PCR and western-blot also certified that the inhibited JNK and p38 further reduced Bax expression and elevated Bcl-2 expression to reduce the expression of caspase-3 to exert anti-apoptosis effects.

CONCLUSION

Taken together, the cardioprotection of GHI mainly incarnated in activating GST P to relieve oxidation properties, thereby inhibiting ASK1-JNK/p38 pathway to suppress apoptosis.

Exogenous 8-hydroxydeoxyguanosine attenuates doxorubicin-induced cardiotoxicity by decreasing pyroptosis in H9c2 cardiomyocytes

Doxorubicin (DOX), which is widely used in cancer treatment, can induce cardiomyopathy. One of the main mechanisms whereby DOX induces cardiotoxicity involves pyroptosis through the NLR family pyrin domain containing 3 (NLRP3) inflammasome and gasdermin D (GSDMD). Increased NAPDH oxidase (NOX) and oxidative stress trigger pyroptosis. Exogenous 8-hydroxydeoxyguanosine (8-OHdG) decreases reactive oxygen species (ROS) production by inactivating NOX. Here, we examined whether 8-OHdG treatment can attenuate DOX-induced pyroptosis in H9c2 cardiomyocytes. Exposure to DOX increased the peroxidative glutathione redox status and NOX1/2/4, toll-like receptor (TLR)2/4, and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) expression, while an additional 8-OHdG treatment attenuated these effects. Furthermore, DOX induced higher expression of NLRP3 inflammasome components, including NLRP3, apoptosis-associated speck-like protein containing a c-terminal caspase recruitment domain (ASC), and pro-caspase-1. Moreover, it increased caspase-1 activity, a marker of pyroptosis, and interleukin (IL)-1β expression. All these effects were attenuated by 8-OHdG treatment. In addition, the expression of the cardiotoxicity markers, atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) was increased by DOX, whereas the increase of ANP and BNP induced by DOX treatment was reversed by 8-OHdG. In conclusion, exogenous 8-OHdG attenuated DOX-induced pyroptosis by decreasing the expression of NOX1/2/3, TLR2/4, and NF-κB. Thus, 8-OHdG may attenuate DOX-induced cardiotoxicity through the inhibition of pyroptosis.

Cardio-Oncology: Mechanisms, Drug Combinations, and Reverse Cardio-Oncology

Chemotherapy, radiotherapy, targeted therapy, and immunotherapy have brought hope to cancer patients. With the prolongation of survival of cancer patients and increased clinical experience, cancer-therapy-induced cardiovascular toxicity has attracted attention. The adverse effects of cancer therapy that can lead to life-threatening or induce long-term morbidity require rational approaches to prevention and treatment, which requires deeper understanding of the molecular biology underpinning the disease. In addition to the drugs used widely for cardio-protection, traditional Chinese medicine (TCM) formulations are also efficacious and can be expected to achieve “personalized treatment” from multiple perspectives. Moreover, the increased prevalence of cancer in patients with cardiovascular disease has spurred the development of “reverse cardio-oncology”, which underscores the urgency of collaboration between cardiologists and oncologists. This review summarizes the mechanisms by which cancer therapy induces cardiovascular toxicity, the combination of antineoplastic and cardioprotective drugs, and recent advances in reverse cardio-oncology.

Publication Trends on Mitophagy in the World and China: A 16-Year Bibliometric Analysis

In the past 16 years, research on mitophagy has increasingly expanded to a wider range of subjects. Therefore, comprehensively analyzing the relevant progress and development trends on mitophagy research requires specific methods. To assess the hotspots, directions, and quality of results in this field worldwide, we used multiple tools to examine research progress and growing trends in research on the matter during the last 16 years (from 2005 to 2020). We also compared the quantity and quality of the literature records on mitophagy published by research institutions in China and other developed countries, reviewed China’s contribution, and examined the gap between China and these developed countries. According to the results of our bibliometric analysis, the United States and its research institutes published the most papers. We identified cell biology as the most commonly researched subject on mitophagy and AUTOPHAGY as the most popular journal for research on mitophagy. We also listed the most cited documents from around the world and China. With gradually increased funding, China is progressively becoming prominent in the field of mitophagy; nevertheless, the gap between her and major countries in the world must be closed.

Influence of Histologic Types and Subtypes on Survival Outcomes of Intermediate-High and High-Risk Renal Cell Carcinoma Following Nephrectomy: Findings From the SEER Database

OBJECTIVE

To understand the influence of histologic subtypes on the survival outcomes of intermediate-high and high-risk renal cell carcinoma (RCC) following nephrectomy.

METHODS

This study employed data files from the SEER Program to identify patients diagnosed with intermediate-high or high risk RCC and treated with nephrectomy. Unadjusted Kaplan Meier curves, and multivariable Cox regression analyses were applied to estimate the hazards of histologic types for overall survival (OS) and cancer-specific survival (CSS).

RESULTS

OS was higher for chromophobe (HR=0.58, 95% CI 0.47-0.70; P<.0001), similar for papillary (HR=0.90, 95% CI 0.80-1.02; P=.11) and worse for sarcomatoid (HR=3.17, 95% CI 2.70-3.72; P<.0001) subtypes relative to the clear cell subtype. OS was lower in the high-risk disease (HR=2.35, 95% CI 2.01-2.74; P <.0001) versus intermediate-high risk disease. CSS was higher for chromophobe (HR=0.47, 95% CI 0.35-0.63; P<.0001), similar for papillary (HR=0.91, 95% CI 0.77-1.08; P=.28) and worse for sarcomatoid (HR=4.19, 95% CI 3.50-5.02; P<.0001) subtypes relative to the clear cell subtype. CSS was lower for the high-risk disease (HR=2.86, 95%CI 2.39-3.43; P <.0001) relative to intermediate-high risk disease.

Autophagic degradation of CCN2 (cellular communication network factor 2) causes cardiotoxicity of sunitinib

Excessive macroautophagy/autophagy is one of the causes of cardiomyocyte death induced by cardiovascular diseases or cancer therapy, yet the underlying mechanism remains unknown. We and other groups previously reported that autophagy might contribute to cardiomyocyte death caused by sunitinib, a tumor angiogenesis inhibitor that is widely used in clinic, which may help to understand the mechanism of autophagy-induced cardiomyocyte death. Here, we found that sunitinib-induced autophagy leads to apoptosis of cardiomyocyte and cardiac dysfunction as the cardiomyocyte-specific Atg7^-/+ heterozygous mice are resistant to sunitinib. Sunitinib-induced maladaptive autophagy selectively degrades the cardiomyocyte survival mediator CCN2 (cellular communication network factor 2) through the TOLLIP (toll interacting protein)-mediated endosome-related pathway and cardiomyocyte-specific knockdown of Ccn2 through adeno-associated virus serotype 9 (AAV9) mimics sunitinib-induced cardiac dysfunction in vivo, suggesting that the autophagic degradation of CCN2 is one of the causes of sunitinib-induced cardiotoxicity and death of cardiomyocytes. Remarkably, deletion of Hmgb1 (high mobility group box 1) inhibited sunitinib-induced cardiomyocyte autophagy and apoptosis, and the HMGB1-specific inhibitor glycyrrhizic acid (GA) significantly mitigated sunitinib-induced autophagy, cardiomyocyte death and cardiotoxicity. Our study reveals a novel target protein of autophagic degradation in the regulation of cardiomyocyte death and highlights the pharmacological inhibitor of HMGB1 as an attractive approach for improving the safety of sunitinib-based cancer therapy.

Role of acetylation in doxorubicin-induced cardiotoxicity

As a potent chemotherapeutic agent, doxorubicin (DOX) is widely used for the treatment of a variety of cancers However, its clinical utility is limited by dose-dependent cardiotoxicity, and pathogenesis has traditionally been attributed to the formation of reactive oxygen species (ROS). Accordingly, the prevention of DOX-induced cardiotoxicity is an indispensable goal to optimize therapeutic regimens and reduce morbidity. Acetylation is an emerging and important epigenetic modification regulated by histone deacetylases (HDACs) and histone acetyltransferases (HATs). Despite extensive studies of the molecular basis and biological functions of acetylation, the application of acetylation as a therapeutic target for cardiotoxicity is in the initial stage, and further studies are required to clarify the complex acetylation network and improve the clinical management of cardiotoxicity. In this review, we summarize the pivotal functions of HDACs and HATs in DOX-induced oxidative stress, the underlying mechanisms, the contributions of noncoding RNAs (ncRNAs) and exercise-mediated deacetylases to cardiotoxicity. Furthermore, we describe research progress related to several important SIRT activators and HDAC inhibitors with potential clinical value for chemotherapy and cardiotoxicity. Collectively, a comprehensive understanding of specific roles and recent developments of acetylation in doxorubicin-induced cardiotoxicity will provide a basis for improved treatment outcomes in cancer and cardiovascular diseases.

Sodium-Glucose CoTransporter-2 Inhibitor Empagliflozin Ameliorates Sunitinib-Induced Cardiac Dysfunction via Regulation of AMPK-mTOR Signaling Pathway-Mediated Autophagy

Background: Sodium–glucose cotransporter-2 (SGLT2) inhibitors have been shown to decrease the adverse cardiac events and risks of cardiovascular mortality among patients with or without diabetes, which has made these drugs promising treatment options for patients with chronic heart failure. Cardiac dysfunction is a common and severe side effect induced by cancer chemotherapies, which seriously affects the prognosis and life quality of tumor patients. However, it is not clear whether SGLT2 inhibitors have cardiovascular benefits in patients with cancer chemotherapy–related cardiac dysfunction. We aimed to determine whether empagliflozin (EMPA), an SGLT2 inhibitor, has a protective role against sunitinib (SNT)-induced cardiac dysfunction in a mouse model.

Methods: Male C57BL/6J mice were randomized into control (control, n = 8), empagliflozin (EMPA, n = 8), sunitinib (SNT, n = 12), or sunitinib and empagliflozin coadministration (SNT + EMPA, n = 12) groups. EMPA, SNT, or SNT-combined EMPA was given via oral gavage for consecutive 28 days. Cardiovascular functions and pathological changes were examined, and the underlying mechanisms of EMPA’s effects were investigated in H9c2 cardiomyocytes.

Results: Mice in the SNT group exhibited dramatically elevated blood pressure (systolic blood pressure [SBP] 134.30 ± 6.455 mmHg vs. 114.85 ± 6.30 mmHg) and impaired left ventricular function (left ventricular ejection fraction [LVEF] 50.24 ± 3.06% vs. 84.92 ± 2.02%), as compared with those of the control group. However, EMPA could ameliorate SNT-induced cardiotoxicity, both in terms of SBP (117.51 ± 5.28 mmHg vs. 134.30 ± 6.455 mmHg) and LVEF (76.18 ± 5.16% vs. 50.24 ± 3.06 %). In H9c2 cardiomyocytes, SNT-induced cardiomyocyte death and cell viability loss as well as dysfunction of adenosine 5’-monophosphate–activated protein kinase–mammalian target of rapamycin (AMPK-mTOR) signaling–mediated autophagy were restored by EMPA. However, these favorable effects mediated by EMPA were blocked by the inhibition of AMPK or autophagy.

Conclusion: EMPA could ameliorate SNT-induced cardiac dysfunction via regulating cardiomyocyte autophagy, which was mediated by the AMPK-mTOR signaling pathway. These findings supported that SGLT2 inhibitor therapy could be a potential cardioprotective approach for cardiovascular complications among patients receiving SNT. However, these favorable effects still need to be validated in clinical trials.

Effects of Cardiotoxins on Cardiac Stem and Progenitor Cell Populations

As research and understanding of the cardiotoxic side-effects of anticancer therapy expands further and the affected patient population grows, notably the long-term survivors of childhood cancers, it is important to consider the full range of myocardial cell types affected. While the direct impacts of these toxins on cardiac myocytes constitute the most immediate damage, over the longer term, the myocardial ability to repair, or adapt to this damage becomes an ever greater component of the disease phenotype. One aspect is the potential for endogenous myocardial repair and renewal and how this may be limited by cardiotoxins depleting the cells that contribute to these processes. Clear evidence exists of new cardiomyocyte formation in adult human myocardium, along with the identification in the myocardium of endogenous stem/progenitor cell populations with pro-regenerative properties. Any effects of cardiotoxins on either of these processes will worsen long-term prognosis. While the role of cardiac stem/progenitor cells in cardiomyocyte renewal appears at best limited (although with stronger evidence of this process in response to diffuse cardiomyocyte loss), there are strong indications of a pro-regenerative function through the support of injured cell survival. A number of recent studies have identified detrimental impacts of anticancer therapies on cardiac stem/progenitor cells, with negative effects seen from both long-established chemotherapy agents such as, doxorubicin and from newer, less overtly cardiotoxic agents such as tyrosine kinase inhibitors. Damaging impacts are seen both directly, on cell numbers and viability, but also on these cells' ability to maintain the myocardium through generation of pro-survival secretome and differentiated cells. We here present a review of the identified impacts of cardiotoxins on cardiac stem and progenitor cells, considered in the context of the likely role played by these cells in the maintenance of myocardial tissue homeostasis.

Oxidative Stress and Hypertension

A link between oxidative stress and hypertension has been firmly established in multiple animal models of hypertension but remains elusive in humans. While initial studies focused on inactivation of nitric oxide by superoxide, our understanding of relevant reactive oxygen species (superoxide, hydrogen peroxide, and peroxynitrite) and how they modify complex signaling pathways to promote hypertension has expanded significantly. In this review, we summarize recent advances in delineating the primary and secondary sources of reactive oxygen species (nicotinamide adenine dinucleotide phosphate oxidases, uncoupled endothelial nitric oxide synthase, endoplasmic reticulum, and mitochondria), the posttranslational oxidative modifications they induce on protein targets important for redox signaling, their interplay with endogenous antioxidant systems, and the role of inflammasome activation and endoplasmic reticular stress in the development of hypertension. We highlight how oxidative stress in different organ systems contributes to hypertension, describe new animal models that have clarified the importance of specific proteins, and discuss clinical studies that shed light on how these processes and pathways are altered in human hypertension. Finally, we focus on the promise of redox proteomics and systems biology to help us fully understand the relationship between ROS and hypertension and their potential for designing and evaluating novel antihypertensive therapies.

Mitochondrial Sirtuins and Doxorubicin-induced Cardiotoxicity

Doxorubicin (DOX) is the most effective and extensively used treatment for many tumors. However, its clinical use is hampered by its cardiotoxicity. DOX-induced mitochondrial dysfunction, which causes reactive oxygen species (ROS) generation, cardiomyocyte death, bioenergetic failure, and decreased cardiac function, is a very important mechanism of cardiotoxicity. These cellular processes are all linked by mitochondrial sirtuins (SIRT3-SIRT4). Mitochondrial sirtuins preserve mitochondrial function by increasing mitochondrial metabolism, inhibiting ROS generation by activating the antioxidant enzyme manganese-dependent superoxide dismutase (MnSOD), decreasing apoptosis by activating the forkhead homeobox type O (FOXO) and P53 pathways, and increasing autophagy through AMP-activated protein kinase (AMPK)/mTOR signaling. Thus, sirtuins function at the control point of many mechanisms involved in DOX-induced cardiotoxicity. In this review, we focus on the role of mitochondrial sirtuins in mitochondrial biology and DOX-induced cardiotoxicity. A further aim is to highlight other mitochondrial processes, such as autophagy (mitophagy) and mitochondrial quality control (MQC), for which the effect of mitochondrial sirtuins on cardiotoxicity is unknown.

Rhabdovirus Infection Is Dependent on Serine/Threonine Kinase AP2-Associated Kinase 1

Rabies virus (RABV) causes a fatal neurological disease in both humans and animals. Understanding the mechanism of RABV infection is vital for prevention and therapy of virulent rabies infection. Our previous proteomics analysis based on isobaric tags for relative and absolute quantitation to identify factors revealed that RABV infection enhanced AP-2-associated protein kinase 1 (AAK1) in N2a cells. In this study, to further confirm the role of AAK1, we showed that RABV infection increased the transcription and expression of AAK1 in N2a cells. AAK1 knockdown significantly decreased RABV infection in both N2a and BHK-21 cells. AAK1 knockout inhibited RABV infection in N2a cells. Furthermore, inhibition of AAK1 kinase activity using sunitinib decreased RABV infection. However, AAK1 overexpression did not change RABV infection in vitro. Therapeutic administration of sunitinib did not significantly improve the survival rate of mice following lethal RABV challenge. In addition, AAK1 knockdown decreased infection in N2a cells by vesicular stomatitis virus, which is another rhabdovirus. These results indicate that rhabdovirus infection is dependent on AAK1 and inhibition of AAK1 is a potential strategy for the prevention and therapy of rabies.

Potential relationship between Sirt3 and autophagy in ovarian cancer

Sirtuin 3 (Sirt3) is an important member of the sirtuin protein family. It is a deacetylase that was previously reported to modulate the level of reactive oxygen species (ROS) production and limit the extent of oxidative damage in cellular components. As an important member of the class III type of histone deacetylases, Sirt3 has also been documented to mediate nuclear gene expression, metabolic control, neuroprotection, cell cycle and proliferation. In ovarian cancer (OC), Sirt3 has been reported to regulate cellular metabolism, apoptosis and autophagy. Sirt3 can regulate autophagy through a variety of different molecular signaling pathways, including the p62, 5'AMP-activated protein kinase and mitochondrial ROS-superoxide dismutase pathways. However, autophagy downstream of Sirt3 and its association with OC remains poorly understood. In the present review, the known characteristics of Sirt3 and autophagy were outlined, and their potential functional roles were discussed. Following a comprehensive analysis of the current literature, Sirt3 and autophagy may either serve positive or negative roles in the regulation of OC. Therefore, it is important to identify the appropriate expression level of Sirt3 to control the activation of autophagy in OC cells. This strategy may prove to be a novel therapeutic method to reduce the mortality of patients with OC. Finally, potential research directions into the association between Sirt3 and other signaling pathways were provided.

MicroRNA-874-5p regulates autophagy and proliferation in pulmonary artery smooth muscle cells by targeting Sirtuin 3

Autophagy is a major cause of pathological vascular remodeling under hypoxic pulmonary hypertension (PH). Sirtuin 3 (Sirt 3) has recently been reported to be involved in the regulation of autophagy, however, its role as an autophagy regulator during hypoxic PH, particularly the molecular mechanism, remains poorly understood. In the present study, Western blot, immunohistochemistry, immunofluorescence, bromodeoxyuridine incorporation and cell cycle analyses were performed to elucidate the underlying mechanism of hypoxia-induced autophagy and cell proliferation with respect to Sirt 3. We observed that the Sirt 3 expression was decreased under hypoxia and that Sirt 3 overexpression significantly inhibited the effects of hypoxia on autophagy. Next, we investigated the mechanistic role of microRNAs in Sirt 3-associated autophagy under hypoxic conditions, with luciferase reporter, microscale thermophoresis and RNA immunoprecipitation assays, results confirming that Sirt 3 is a direct target of miR-874-5p. Furthermore, miR-874-5p was upregulated following hypoxia, and miR-874-5p depletion in turn inhibited autophagy and consequently suppressed abnormal smooth muscle cell proliferation. These findings provide insight into the contribution of the miR-874-5p/Sirt 3 cascade with regard to changes in autophagy and proliferation associated with PH.

Sirt3 promotes hepatocellular carcinoma cells sensitivity to regorafenib through the acceleration of mitochondrial dysfunction

Regorafenib, a multiple kinase inhibitor, is recently approved for treatment of patients with advanced hepatocellular carcinoma (HCC). Previous studies demonstrated that regorafenib was a mitochondrial toxicant, which associated with the impairment of mitochondria. Sirt3 is involved in the regulation of mitochondrial function in cancers. This study aimed to investigate the mechanism of Sirt3 involved in the mitochondrial dysfunction which associated with regorafenib treatment in liver cancer cells. We found regorafenib inhibited Sirt3 and p-ERK expression in HCC cells in a dose-dependent manner. Bioinformatics analysis showed that Sirt3 expression was down-regulated in liver cancer tissues and its low expression was correlated with worse overall survival (OS) in liver cancer patients. After transfected with Sirt3 overexpression plasmid, we found that Sirt3 sensitized liver cancer cells to regorafenib and resulted in much more apoptosis with a significant increase of ROS level. However, exogenous antioxidant could not weaken the apoptosis. Mitochondrial membrane potential assay indicated that Sirt3 overexpression accelerated the mitochondrial depolarization process induced by regorafenib and aggravated mitochondrial injury. Cellular oxygen consumption assay showed that mitochondrial dysfunction was caused by the damage of the electron transport chain. The results demonstrated that Sirt3 overexpression promoted the increase of ROS and apoptosis induced by regorafenib through the acceleration of mitochondrial dysfunction by impairing function of the electron transport chain in liver cancer cells. Our studies verified the functional role of Sirt3 in regorafenib treatment and suggested that regorafenib accompanied with Sirt3 activator as a novel treatment strategy for HCC.

Dihydromyricetin alleviates doxorubicin-induced cardiotoxicity by inhibiting NLRP3 inflammasome through activation of SIRT1

Doxorubicin (DOX) is a powerful anthracycline antineoplastic drug whose clinical application is limited by serious cardiotoxic side effects. Dihydromyricetin (DHM), a flavonoid compound extracted from the Japanese raisin tree (Hovenia dulcis), is cardioprotective in patients with heart failure; however, the underlying mechanisms are poorly understood. The aim of this study was to assess the possible anti-inflammatory properties of DHM in a rat model of DOX-induced cardiotoxicity and DOX-treated H9C2 cells, and gain insights into the molecular mechanisms that mediate these effects. The results showed that DHM treatment significantly improved the myocardial structure and function in DOX-exposed rats by alleviating NLRP3 inflammasome-mediated inflammation. DHM also inhibited DOX-induced activation of the NLRP3 inflammasome in H9C2 cells. This effect was mediated by inhibition of caspase-1 activity, suppression of IL-1β and IL-18 release, and upregulation of SIRT1 protein levels in vivo and in vitro. Moreover, selective inhibition of SIRT1 blocked the protective effects of DHM. Collectively, our findings indicate that DHM protects against DOX-induced cardiotoxicity by inhibiting NLRP3 inflammasome activation via stimulation of the SIRT1 pathway.

Targeted inhibition of ULK1 enhances daunorubicin sensitivity in acute myeloid leukemia

PURPOSE

In acute myeloid leukemia (AML), complete remission can be achieved in parts of patients using cytarabine/anthracycline combination-based chemotherapy, however, drug resistance-related recurrence is still a common cause of treatment failure, leading to high mortality among patients. In our research, we revealed the molecular mechanisms that were sufficient to improve sensitivity of AML cells to the anthracycline daunorubicin (DNR).

METHODS

We evaluated the effects of autophagy and apoptosis induced by DNR using two AML cell lines HL60 and U937.Western blot was preformed to analyze the apoptotic pathway protein expression and flow cytometric analysis was used to detect the level of apoptosis in AML cells. The levels of autophagy-related proteins were detected by western blotting and autophagic vesicles were observed by electron microscopy.

RESULTS

DNR effectively induced autophagy in two AML cell lines HL60 and U937 confirming by upregulation of LC3-II lipidation, formation of autophagosomes. Inhibition of autophagy by pharmacologic inhibitor HCQ promoted apoptosis induced by DNR, suggesting that autophagy played a vital role in pro-survival in AML. Furthermore, ULK1 inhibition by a highly selective kinase inhibitor SBI-0206965 and shRNA enhanced cytotoxicity of DNR against AML cells. Independent of mTOR -ULK1 signaling pathway, activation of autophagy of DNR was proved to be mediated by AMPK (pThr172)/ULK1 pathway.

CONCLUSIONS

These results revealed that pro-survival autophagy induced by ULK1 activation was one of the potential mechanisms of AML resistance to DNR. Targeting ULK1 selectively could be a promising therapeutic strategy to enhance sensitivity of DNR for AML therapy.