Doxorubicin Regulates Autophagy Signals via Accumulation of Cytosolic Ca2+ in Human Cardiac Progenitor Cells

6PPD induced cardiac dysfunction in zebrafish associated with mitochondrial damage and inhibition of autophagy processes

The compound 6PPD is widely acknowledged for its antioxidative properties; however, concerns regarding its impact on aquatic organisms have spurred comprehensive investigations. In our study, we advanced our comprehension by revealing that exposure to 6PPD could induce cardiac dysfunction, myocardial injury and DNA damage in adult zebrafish. Furthermore, our exploration unveiled that the exposure of cardiomyocytes to 6PPD resulted in apoptosis and mitochondrial injury, as corroborated by analyses using transmission electron microscopy and flow cytometry. Significantly, our study demonstrated the activation of the autophagy pathway in both the heart of zebrafish and cardiomyocytes, as substantiated by transmission electron microscopy and immunofluorescent techniques. Importantly, the increased the expression of P62 in the heart and cardiomyocytes suggested an inhibition of the autophagic process. The reduction in autophagy flux was also verified through in vivo experiments involving the infection of mCherry-GFP-LC3. We further identified that the fusion of autophagosomes and lysosomes was impaired in the 6PPD treatment group. In summary, our findings indicated that the impaired fusion of autophagosomes and lysosomes hampered the autophagic degradation process, leading to apoptosis and ultimately resulting in cardiac dysfunction and myocardial injury. This study discovered the crucial role of the autophagy pathway in regulating 6PPD-induced cardiotoxicity. SYNOPSIS: 6PPD exposure inhibited the autophagic degradation process and induced mitochondrial injury and apoptosis in the heart of adult zebrafish.

The Protective Role of Glutathione against Doxorubicin-Induced Cardiotoxicity in Human Cardiac Progenitor Cells

This study investigated the protective effect of glutathione (GSH), an antioxidant drug, against doxorubicin (DOX)-induced cardiotoxicity. Human cardiac progenitor cells (hCPCs) treated with DOX (250 to 500 nM) showed increased viability and reduced ROS generation and apoptosis with GSH treatment (0.1 to 1 mM) for 24 h. In contrast to the 500 nM DOX group, pERK levels were restored in the group co-treated with GSH and suppression of ERK signaling improved hCPCs' survival. Similarly to the previous results, the reduced potency of hCPCs in the 100 nM DOX group, which did not affect cell viability, was ameliorated by co-treatment with GSH (0.1 to 1 mM). Furthermore, GSH was protected against DOX-induced cardiotoxicity in the in vivo model (DOX 20 mg/kg, GSH 100 mg/kg). These results suggest that GSH is a potential therapeutic strategy for DOX-induced cardiotoxicity, which performs its function via ROS reduction and pERK signal regulation.

Pretreatment of 3-MA prevents doxorubicin-induced cardiotoxicity through inhibition of autophagy initiation

Anthracycline antineoplastics are effective in the treatment of hematological malignancies and solid tumors. However, the anthracycline-induced cardiotoxicity (AIC) limits their use as chemotherapeutic agents. Autophagy-based therapies have been explored to prevent AIC. Yet, whether inhibition of autophagy during its early stage could alleviate AIC remains unclear. In this study, we firstly observed the activation of autophagy during AIC in both cardiomyocyte cell lines AC16 and H9c2. Moreover, knockdown of Atg7, a key regulatory factor in early autophagy, could ameliorate the effects of DOX-induced AIC. Importantly, the use of early autophagy inhibitor 3-MA protected cardiomyocyte cells from DOX-induced cardiotoxicity in vitro and in a chronic AIC mouse model. Our findings demonstrate that inhibiting early stage of autophagy may be an effective preventative therapeutic strategy to protect cardiac function from AIC.

Doxorubicin downregulates autophagy to promote apoptosis-induced dilated cardiomyopathy via regulating the AMPK/mTOR pathway

The broad-spectrum antineoplastic drug doxorubicin (DOX) has one of the most serious chronic side effects on the heart, dilated cardiomyopathy, but the precise molecular mechanisms underlying disease progression subsequent to long latency periods remain puzzling. Here, we established a model of DOX-induced dilated cardiomyopathy. In a cardiac cytology exploration, we found that differentially expressed genes in the KEGG signaling pathway enrichment provided a novel complex network of mTOR bridging autophagy and oxidative stress. Validation results showed that DOX caused intracellular reactive oxygen species accumulation in cardiomyocytes, disrupted mitochondria, led to imbalanced intracellular energy metabolism, and triggered cardiomyocyte apoptosis. Apoptosis showed a negative correlation with DOX-regulated cardiomyocyte autophagy. To evaluate whether the inhibition of mTOR could upregulate autophagy to protect cardiomyocytes, we used rapamycin to restore autophagy depressed by DOX. Rapamycin increased cardiomyocyte survival by easing the autophagic flux blocked by DOX. In addition, rapamycin reduced oxidative stress, prevented mitochondrial damage, and restored energy metabolic homeostasis in DOX-treated cardiomyocytes. In vivo, we used metformin (Met) which is an AMPK activator to protect cardiac tissue to alleviate DOX-induced dilated cardiomyopathy. In this study, Met significantly attenuated the oxidative stress response of myocardial tissue caused by DOX and activated cardiomyocyte autophagy to maintain cardiomyocyte energy metabolism and reduce cardiomyocyte apoptosis by downregulating mTOR activity. Overall, our study revealed the role of autophagy and apoptosis in DOX-induced dilated cardiomyopathy and demonstrated the potential role of regulation of the AMPK/mTOR axis in the treatment of DOX-induced dilated cardiomyopathy.

Mitochondrial quality control mechanisms as therapeutic targets in doxorubicin-induced cardiotoxicity

Doxorubicin (DOX) is a chemotherapeutic drug that is utilized for solid tumors and hematologic malignancies, but its clinical application is hampered by life-threatening cardiotoxicity including cardiac dilation and heart failure. Mitochondrial quality control processes, including mitochondrial proteostasis, mitophagy, and mitochondrial dynamics and biogenesis, serve to maintain mitochondrial homeostasis in the cardiovascular system. Importantly, recent advances have unveiled a major role for defective mitochondrial quality control in the etiology of DOX cardiomyopathy. Moreover, specific interventions targeting these quality control mechanisms to preserve mitochondrial function have emerged as potential therapeutic strategies to attenuate DOX cardiotoxicity. However, clinical translation is challenging because of obscure mechanisms of action and potential adverse effects. The purpose of this review is to provide new insights regarding the role of mitochondrial quality control in the pathogenesis of DOX cardiotoxicity, and to explore promising therapeutic approaches targeting these mechanisms to aid clinical management.

Dihydromyricetin protects against Doxorubicin-induced cardiotoxicity through activation of AMPK/mTOR pathway

BACKGROUND

Doxorubicin (DOX) is a highly effective broad-spectrum antitumor agent, but its clinical administration is limited by self-induced cardiotoxicity. Dihydromyricetin (DHM) is a flavonoid compound extracted from the Japanese raisin tree. Evidence that DHM has neovascular protective properties makes it a candidate for studying cardiotoxicity prevention strategy. However, it remains unknown if DHM can protect against cardiotoxicity caused by DOX.

PURPOSE

The present study was performed to evaluate the protective effect of DHM on DOX-induced cardiotoxicity in vivo and in vitro.

METHODS

C57BL/6 mice were intraperitoneally injected with DOX to construct cardiac injury model in vivo, and AC16 cells were exposed to DOX to induce cell injury in vitro. Left ventricular function of mice were detected by echocardiography, the apoptosis of mice cardiac tissue and AC16 cells were detected by TUNEL and Hoechst33342/PI double staining. The expression of apoptosis and autophagy related proteins were detected by western blotting, immunohistochemical staining and immunofluorescence staining.

RESULTS

Echocardiographic results showed that DOX-induced cardiotoxicity were significantly alleviated by DHM pretreatment. DOX induced cardiotoxicity of mice by inhibiting AMPK activation, increasing apoptosis and decreasing autophagy. However, under the same conditions, the heart tissue of DHM-pretreated mice showed increased autophagy and decreased apoptosis via activation AMPK/mTOR pathway. The same results were observed in vitro, and it was also found that DHM can inhibit the production of intracellular ROS in vitro.

CONCLUSION

DHM protects against cardiotoxicity by inhibiting apoptosis and oxidative stress and it can allevate theautophagy inhibition caused by DOX through AMPK/mTOR pathway. DHM preconditioning may be a breakthrough in protecting DOX-induced cardiotoxicity in the future clinical applications.

Elabela ameliorates doxorubicin-induced cardiotoxicity by promoting autophagic flux through TFEB pathway

Doxorubicin (DOX) is a widely used and effective antineoplastic drug; however, its clinical application is limited by cardiotoxicity. A safe and effective strategy to prevent from doxorubicin-induced cardiotoxicity (DIC) is still beyond reach. Elabela (ELA), a new APJ ligand, has exerted cardioprotective effect against multiple cardiovascular diseases. Here, we asked whether ELA alleviates DIC. Mice were injected with DOX to established acute DIC. In vivo studies were assessed with echocardiography, serum cTnT and CK-MB, HW/BW ratio and WGA staining. Cell death and atrophy were measured by AM/PI staining and phalloidin staining respectively in vitro. Autophagic flux was monitored with Transmission electron microscopy in vivo, as well as LysoSensor and mRFP-GFP-LC3 puncta in vitro. Our results showed that ELA improved cardiac dysfunction in DIC mice. ELA administration also attenuated cell death and atrophy in DOX-challenged neonatal rat cardiomyocytes (NRCs). Additionally, we found that ELA restored DOX-induced autophagic flux blockage, which was evidenced by the reverse of p62 and LC3II, improvement of lysosome function and accelerated degradation of accumulated autolysosomes. Chloroquine, a classical autophagic flux inhibitor, blunted the improvement of ELA on cardiac dysfunction. At last, we revealed that ELA reversed DOX-induced downregulation of transcription factor EB (TFEB), and silencing TFEB by siRNA abrogated the effects of ELA on autophagic flux as well as cell death and atrophy in NRCs. In conclusion, this study indicated that ELA ameliorated DIC through enhancing autophagic flux via activating TFEB. ELA may become a potential target against DIC.

Epigallocatechin-3-gallate pretreatment alleviates doxorubicin-induced ferroptosis and cardiotoxicity by upregulating AMPKα2 and activating adaptive autophagy

Reports indicate that the mechanism of doxorubicin (Dox)-induced cardiotoxicity is very complex, involving multiple regulatory cell death forms. Furthermore, the clinical intervention effect is not ideal. Iron dependence, abnormal lipid metabolism, and excess reactive oxygen species generation, three characteristics of ferroptosis, are potential therapeutic intervention targets. Here, we confirmed in vitro and in vivo that at least autophagy, apoptosis, and ferroptosis are involved in Dox cardiotoxicity-induced damage. When the neonatal rat cardiomyocytes and H9C2 cells or C57BL/6 mice were subjected to Dox-induced cardiotoxicity, epigallocatechin-3-gallate pretreatment could effectively decrease iron accumulation, inhibit oxidative stress and abnormal lipid metabolism, and thereby alleviate Dox cardiotoxicity-induced ferroptosis and protect the myocardium according to multiple functional, enzymatic, and morphological indices. The underlying mechanism was verified to involve the upregulation and activation of AMP-activated protein kinase α2, which promoted adaptive autophagy, increased energy supply, and maintained mitochondrial function. We believe that epigallocatechin-3-gallate is a candidate phytochemical against Dox-induced cardiotoxicity.

Pretreatment of cardiac progenitor cells with bradykinin attenuates H2O2-induced cell apoptosis and improves cardiac function in rats by regulating autophagy

Background

Previous studies have demonstrated that human cardiac c-Kit⁺ progenitor cells (hCPCs) can effectively improve ischemic heart disease. However, the major challenge in applying hCPCs to clinical therapy is the low survival rate of graft hCPCs in the host heart, which limited the benefit of transplanted hCPCs. Bradykinin (BK) is a principal active agent of the tissue kinin-kallikrein system. Our previous studies have highlighted that BK mediated the growth and migration of CPCs by regulating Ca²⁺ influx. However, the protective effect of BK on CPCs, improvement in the survival rate of BK-pretreated hCPCs in the infarcted heart, and the related mechanism remain elusive.

Methods

HCPCs were treated with H₂O₂ to induce cell apoptosis and autophagy, and different concentration of BK was applied to rescue the H₂O₂-induced injury detected by MTT assay, TUNEL staining, flow cytometry, western blotting, and mitoSOX assays. The role of autophagy in the anti-apoptotic effect of BK was chemically activated or inhibited using the autophagy inducer, rapamycin, or the inhibitor, 3-methyladenine (3-MA). To explore the protective effect of BK on hCPCs, 3-MA or BK-pretreated hCPCs were transplanted into the myocardial infarcted rats. An echocardiogram was used to determine cardiac function, H&E and Masson staining were employed to assess pathological characteristics, HLA gene expression was quantified by qRT-PCR, and immunostaining was applied to examine neovascularization using confocal microscopy.

Results

The in vitro results showed that BK suppressed H₂O₂-induced hCPCs apoptosis and ROS production in a concentration-dependent manner by promoting pAkt and Bcl-2 expression and reducing cleaved caspase 3 and Bax expression. Moreover, BK restrained the H₂O₂-induced cell autophagy by decreasing LC3II/I, Beclin1, and ATG5 expression and increasing P62 expression. In the in vivo experiment, the transplanted BK- or 3-MA-treated hCPCs were found to be more effectively improved cardiac function by decreasing cardiomyocyte apoptosis, inflammatory infiltration, and myocardial fibrosis, and promoting neovascularization in the infarcted heart, compared to untreated-hCPCs or c-kit^- cardiomyocytes (CPC^- cells).

Conclusions

Our present study established a new method to rescue transplanted hCPCs in the infarcted cardiac area via regulating cell apoptosis and autophagy of hCPCs by pretreatment with BK, providing a new therapeutic option for heart failure.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-021-02503-6.

An update of the molecular mechanisms underlying doxorubicin plus trastuzumab induced cardiotoxicity

Cardiotoxicity is a major side effect of the chemotherapeutic drug doxorubicin (Dox), which is further exacerbated when it is combined with trastuzumab, a standard care approach for Human Epidermal growth factor Receptor-type 2 (HER2) positive cancer patients. However, the molecular mechanisms of the underlying cardiotoxicity of this combination are still mostly elusive. Increased oxidative stress, impaired energetic substrate uses and topoisomerase IIB inhibition are among the biological processes proposed to explain Dox-induced cardiomyocyte dysfunction. Since cardiomyocytes express HER2, trastuzumab can also damage these cells by interfering with neuroregulin-1 signaling and mitogen-activated protein kinase (MAPK), phosphoinositide 3-kinase (PI3K)/Akt and focal adhesion kinase (FAK)-dependent pathways. Nevertheless, Dox and trastuzumab target other cardiac cell types, such as endothelial cells, fibroblasts, cardiac progenitor cells and leukocytes, which can contribute to the clinical cardiotoxicity observed. This review aims to summarize the current knowledge on the cardiac signaling pathways modulated by these two antineoplastic drugs highly used in the management of breast cancer, not only focusing on cardiomyocytes but also to broaden the knowledge of the potential impact on other cells found in the heart.

Oxoglaucine mediates Ca2+ influx and activates autophagy to alleviate osteoarthritis through the TRPV5/calmodulin/CAMK-II pathway

BACKGROUND AND PURPOSE

Stimulation of calcium influx and suppression of autophagy play important roles in the pathogenesis of osteoarthritis (OA). In this study, we used a novel inhibitor of TRPV5 cation channels - oxoglaucine to attenuate progression of deterioration and pathological changes in OA patient-derived chondrocytes and OA animal model, by activating autophagy.

EXPERIMENTAL APPROACH

Inhibition by oxoglaucine of calcium influx was assessed in cells.. Analyses were also carried out to investigate the effect of oxoglaucine on OA by detection of anti-inflammatory response, TRPV5/CAMK-II/calmodulin pathway, autophagy, and cartilage protection both in vitro and in vivo. demonstrated by macroscopic evaluation and histological findings.

KEY RESULTS

Oxoglaucine suppressed expression of proinflammatory and apoptosis-related proteins, including TNF-α, IL-6, IL-1β, MMP-13, CASP-3, and BAX, and prevented matrix degradation in OA chondrocytes. It also successfully blocked Ca²⁺ influx, activating autophagy dose-dependently asshown by up-regulated expression of LC-3II/I, Beclin-1, ATG5, ATG7, higher autophagic influx and formation of autophagic vesicles. It also decreased expression of mRNA and protein of TRPV5, CAMK-II, and calmodulin. Conversely, 1,25-dihydroxyvitamin D3, anagonist of TRPV5 channels, reversed the oxoglaucine-induced calcium influx inhibition and autophagy activation, demonstrating the association of oxoglaucine with TRPV5. Further, oxoglaucine prevented the apoptosis and matrix degradation of articular cartilage in a rat model of OA.

CONCLUSION AND IMPLICATIONS

Oxoglaucine protects against cartilage damage by blocking the TRPV5/CAMK-II/calmodulin pathway to inhibit Ca²⁺ influx and activate autophagy. Our results indicate that oxoglaucine has the potential to become a candidate drug for treatment of OA.

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.

Regulated cell death pathways in doxorubicin-induced cardiotoxicity

Doxorubicin is a chemotherapeutic drug used for the treatment of various malignancies; however, patients can experience cardiotoxic effects and this has limited the use of this potent drug. The mechanisms by which doxorubicin kills cardiomyocytes has been elusive and despite extensive research the exact mechanisms remain unknown. This review focuses on recent advances in our understanding of doxorubicin induced regulated cardiomyocyte death pathways including autophagy, ferroptosis, necroptosis, pyroptosis and apoptosis. Understanding the mechanisms by which doxorubicin leads to cardiomyocyte death may help identify novel therapeutic agents and lead to more targeted approaches to cardiotoxicity testing.

Metabolic Aspects of Anthracycline Cardiotoxicity

OPINION STATEMENT

Heart failure (HF) is increasingly recognized as the major complication of chemotherapy regimens. Despite the development of modern targeted therapies such as monoclonal antibodies, doxorubicin (DOXO), one of the most cardiotoxic anticancer agents, still remains the treatment of choice for several solid and hematological tumors. The insurgence of cardiotoxicity represents the major limitation to the clinical use of this potent anticancer drug. At the molecular level, cardiac side effects of DOXO have been associated to mitochondrial dysfunction, DNA damage, impairment of iron metabolism, apoptosis, and autophagy dysregulation. On these bases, the antioxidant and iron chelator molecule, dexrazoxane, currently represents the unique FDA-approved cardioprotectant for patients treated with anthracyclines.A less explored area of research concerns the impact of DOXO on cardiac metabolism. Recent metabolomic studies highlight the possibility that cardiac metabolic alterations may critically contribute to the development of DOXO cardiotoxicity. Among these, the impairment of oxidative phosphorylation and the persistent activation of glycolysis, which are commonly observed in response to DOXO treatment, may undermine the ability of cardiomyocytes to meet the energy demand, eventually leading to energetic failure. Moreover, increasing evidence links DOXO cardiotoxicity to imbalanced insulin signaling and to cardiac insulin resistance. Although anti-diabetic drugs, such as empagliflozin and metformin, have shown interesting cardioprotective effects in vitro and in vivo in different models of heart failure, their mechanism of action is unclear, and their use for the treatment of DOXO cardiotoxicity is still unexplored.This review article aims at summarizing current evidence of the metabolic derangements induced by DOXO and at providing speculations on how key players of cardiac metabolism could be pharmacologically targeted to prevent or cure DOXO cardiomyopathy.

Pharmacological inhibition of mTOR attenuates replicative cell senescence and improves cellular function via regulating the STAT3-PIM1 axis in human cardiac progenitor cells

The mammalian target of rapamycin (mTOR) signaling pathway efficiently regulates the energy state of cells and maintains tissue homeostasis. Dysregulation of the mTOR pathway has been implicated in several human diseases. Rapamycin is a specific inhibitor of mTOR and pharmacological inhibition of mTOR with rapamycin promote cardiac cell generation from the differentiation of mouse and human embryonic stem cells. These studies strongly implicate a role of sustained mTOR activity in the differentiating functions of embryonic stem cells; however, they do not directly address the required effect for sustained mTOR activity in human cardiac progenitor cells. In the present study, we evaluated the effect of mTOR inhibition by rapamycin on the cellular function of human cardiac progenitor cells and discovered that treatment with rapamycin markedly attenuated replicative cell senescence in human cardiac progenitor cells (hCPCs) and promoted their cellular functions. Furthermore, rapamycin not only inhibited mTOR signaling but also influenced signaling pathways, including STAT3 and PIM1, in hCPCs. Therefore, these data reveal a crucial function for rapamycin in senescent hCPCs and provide clinical strategies based on chronic mTOR activity.

Mitochondrial Determinants of Doxorubicin-Induced Cardiomyopathy

Anthracycline-based chemotherapy can result in the development of a cumulative and progressively developing cardiomyopathy. Doxorubicin is one of the most highly prescribed anthracyclines in the United States due to its broad spectrum of therapeutic efficacy. Interference with different mitochondrial processes is chief among the molecular and cellular determinants of doxorubicin cardiotoxicity, contributing to the development of cardiomyopathy. The present review provides the basis for the involvement of mitochondrial toxicity in the different functional hallmarks of anthracycline toxicity. Our objective is to understand the molecular determinants of a progressive deterioration of functional integrity of mitochondria that establishes a historic record of past drug treatments (mitochondrial memory) and renders the cancer patient susceptible to subsequent regimens of drug therapy. We focus on the involvement of doxorubicin-induced mitochondrial oxidative stress, disruption of mitochondrial oxidative phosphorylation, and permeability transition, contributing to altered metabolic and redox circuits in cardiac cells, ultimately culminating in disturbances of autophagy/mitophagy fluxes and increased apoptosis. We also suggest some possible pharmacological and nonpharmacological interventions that can reduce mitochondrial damage. Understanding the key role of mitochondria in doxorubicin-induced cardiomyopathy is essential to reduce the barriers that so dramatically limit the clinical success of this essential anticancer chemotherapy.

Protective effect of flavonoids from Rosa roxburghii Tratt on myocardial cells via autophagy

The aim of this study is to explore the effect of flavonoids from Rosa roxburghii Tratt (FRRT) on doxorubicin (DOX)-induced autophagy of myocardial cells. Primary isolation and culture of myocardial cells and H9C2 myocardial cell lines from 1 to 3-day-old rats were performed, myocardial cells were incubated using 5 μmol/L DOX and a cardiotoxicity model was established, intervention was conducted via FRRT, and the ultrastructure of myocardial cells was observed under a transmission electron microscope. The expressions of LC3-II and P62 proteins were detected through immunofluorescence and Western blotting. The ultrastructure showed a large quantity of autophagic vacuoles of the cells in DOX group with poor cell state. After the FRRT intervention, only a small quantity of autophagic vacuoles appeared in the myocardial cells, and there were many coarse microvilli on the cell surface. The expression of P62 protein was reduced in DOX group, while that in FRRT group was increased (p < 0.01). In conclusion, FRRT exerts a protective effect in the DOX-induced cardiotoxicity by down-regulating DOX-induced autophagy of myocardial cells.

Pulsed-wave Ultrasound Hyperthermia Enhanced Nanodrug Delivery Combined with Chloroquine Exerts Effective Antitumor Response and Postpones Recurrence

Autophagy is found to serve as a surviving mechanism for cancer cells. Inhibiting autophagy has been considered as an adjuvant anti-cancer strategy. In this study, we investigated the anti-tumor effect of combining pulsed-wave ultrasound hyperthermia (pUH) enhanced PEGylated liposomal doxorubicin (PLD) delivery with an autophagy inhibitor chloroquine (CQ). BALB/c mice bearing subcutaneous 4T1 tumor received intravenous injection of PLD (10 mg/kg) plus 15-minute on-tumor pUH on Day 5 after tumor implantation and were then fed with CQ (50 mg/kg daily) thereafter. Prolonged suppression of tumor growth was attained with PLD + pUH + CQ treatment, whereas in PLD + pUH group tumors quickly recurred after an initial inhibition. Treatment with CQ monotherapy had no benefit compared to the control group. Immunohistochemical staining and Western blotting showed that autophagy of cancer cells was blocked for the mice receiving CQ. It indicates that PLD + pUH + CQ is a promising strategy to treat cancer for a long-term inhibition.

Tanshinone IIA Restores Dynamic Balance of Autophagosome/Autolysosome in Doxorubicin-Induced Cardiotoxicity via Targeting Beclin1/LAMP1

Clinical use of the anti-cancer drug doxorubicin (DOX) is largely limited due to its severe cardiotoxicity. Dysregulation of autophagy is implicated in DOX-induced cardiotoxicity (DIC). Prior studies have indicated that Beclin1 and lysosomal-associated membrane proteins-1 (LAMP1) are critical mediators of autophagy. In this work, by assessing autophagic flux in a DOX-stimulated H9C2 model, we observed autolysosome accumulation caused by interruption of autolysosome degradation. Tanshinone IIA (TSA) is a well-known small molecule that exerts impressive cardioprotective effects on heart failure. Here, we investigated the regulation of TSA in DOX-treated zebrafish, mice, and H9C2 models. Results demonstrated that TSA remarkably improved heart function and reversed pathological changes in vivo, while TSA restored autophagic flux by promoting autolysosome degradation and autophagosome formation. Further experiments demonstrated that these effects were mediated through upregulation of Beclin1 and LAMP1. The mTOR agonist MHY1485 was shown to abrogate the effect of TSA via the UNC-51-like kinase 1 (ULK1)-Beclin1/TFEB-LAMP1 signaling pathway in vitro, demonstrating that TSA protects against DIC by promoting autophagy via the Beclin1/LAMP1 signaling pathway. We further employed a U87 model to assess whether TSA would compromise the antitumor activity of DOX. Intriguingly, the co-treatment of TSA was able to synergistically inhibit proliferative activity. Collectively, in this study we uncover the novel insight that TSA is able to reduce the cardiotoxicity of DOX without compromising antitumor activity.

Therapeutic Cell Protective Role of Histochrome under Oxidative Stress in Human Cardiac Progenitor Cells

Cardiac progenitor cells (CPCs) are resident stem cells present in a small portion of ischemic hearts and function in repairing the damaged heart tissue. Intense oxidative stress impairs cell metabolism thereby decreasing cell viability. Protecting CPCs from undergoing cellular apoptosis during oxidative stress is crucial in optimizing CPC-based therapy. Histochrome (sodium salt of echinochrome A—a common sea urchin pigment) is an antioxidant drug that has been clinically used as a pharmacologic agent for ischemia/reperfusion injury in Russia. However, the mechanistic effect of histochrome on CPCs has never been reported. We investigated the protective effect of histochrome pretreatment on human CPCs (hCPCs) against hydrogen peroxide (H₂O₂)-induced oxidative stress. Annexin V/7-aminoactinomycin D (7-AAD) assay revealed that histochrome-treated CPCs showed significant protective effects against H₂O₂-induced cell death. The anti-apoptotic proteins B-cell lymphoma 2 (Bcl-2) and Bcl-xL were significantly upregulated, whereas the pro-apoptotic proteins BCL2-associated X (Bax), H₂O₂-induced cleaved caspase-3, and the DNA damage marker, phosphorylated histone (γH2A.X) foci, were significantly downregulated upon histochrome treatment of hCPCs in vitro. Further, prolonged incubation with histochrome alleviated the replicative cellular senescence of hCPCs. In conclusion, we report the protective effect of histochrome against oxidative stress and present the use of a potent and bio-safe cell priming agent as a potential therapeutic strategy in patient-derived hCPCs to treat heart disease.

Towards frailty biomarkers: Candidates from genes and pathways regulated in aging and age-related diseases

OBJECTIVE

Use of the frailty index to measure an accumulation of deficits has been proven a valuable method for identifying elderly people at risk for increased vulnerability, disease, injury, and mortality. However, complementary molecular frailty biomarkers or ideally biomarker panels have not yet been identified. We conducted a systematic search to identify biomarker candidates for a frailty biomarker panel.

METHODS

Gene expression databases were searched (http://genomics.senescence.info/genes including GenAge, AnAge, LongevityMap, CellAge, DrugAge, Digital Aging Atlas) to identify genes regulated in aging, longevity, and age-related diseases with a focus on secreted factors or molecules detectable in body fluids as potential frailty biomarkers. Factors broadly expressed, related to several "hallmark of aging" pathways as well as used or predicted as biomarkers in other disease settings, particularly age-related pathologies, were identified. This set of biomarkers was further expanded according to the expertise and experience of the authors. In the next step, biomarkers were assigned to six "hallmark of aging" pathways, namely (1) inflammation, (2) mitochondria and apoptosis, (3) calcium homeostasis, (4) fibrosis, (5) NMJ (neuromuscular junction) and neurons, (6) cytoskeleton and hormones, or (7) other principles and an extensive literature search was performed for each candidate to explore their potential and priority as frailty biomarkers.

RESULTS

A total of 44 markers were evaluated in the seven categories listed above, and 19 were awarded a high priority score, 22 identified as medium priority and three were low priority. In each category high and medium priority markers were identified.

CONCLUSION

Biomarker panels for frailty would be of high value and better than single markers. Based on our search we would propose a core panel of frailty biomarkers consisting of (1) CXCL10 (C-X-C motif chemokine ligand 10), IL-6 (interleukin 6), CX3CL1 (C-X3-C motif chemokine ligand 1), (2) GDF15 (growth differentiation factor 15), FNDC5 (fibronectin type III domain containing 5), vimentin (VIM), (3) regucalcin (RGN/SMP30), calreticulin, (4) PLAU (plasminogen activator, urokinase), AGT (angiotensinogen), (5) BDNF (brain derived neurotrophic factor), progranulin (PGRN), (6) α-klotho (KL), FGF23 (fibroblast growth factor 23), FGF21, leptin (LEP), (7) miRNA (micro Ribonucleic acid) panel (to be further defined), AHCY (adenosylhomocysteinase) and KRT18 (keratin 18). An expanded panel would also include (1) pentraxin (PTX3), sVCAM/ICAM (soluble vascular cell adhesion molecule 1/Intercellular adhesion molecule 1), defensin α, (2) APP (amyloid beta precursor protein), LDH (lactate dehydrogenase), (3) S100B (S100 calcium binding protein B), (4) TGFβ (transforming growth factor beta), PAI-1 (plasminogen activator inhibitor 1), TGM2 (transglutaminase 2), (5) sRAGE (soluble receptor for advanced glycosylation end products), HMGB1 (high mobility group box 1), C3/C1Q (complement factor 3/1Q), ST2 (Interleukin 1 receptor like 1), agrin (AGRN), (6) IGF-1 (insulin-like growth factor 1), resistin (RETN), adiponectin (ADIPOQ), ghrelin (GHRL), growth hormone (GH), (7) microparticle panel (to be further defined), GpnmB (glycoprotein nonmetastatic melanoma protein B) and lactoferrin (LTF). We believe that these predicted panels need to be experimentally explored in animal models and frail cohorts in order to ascertain their diagnostic, prognostic and therapeutic potential.

[Study on the protective mechanism of autophagy on cartilage by magnesium sulfate]

Objective

To investigate the mechanism of magnesium sulfate in protecting rabbit cartilage by initiating autophagy.

Methods

Twenty-four adult female New Zealand rabbits were used to prepare post-traumatic osteoarthritis (PTOA) models by anterior cruciate ligament transection. Then, the PTOA models were randomly divided into PTOA group, distilled water group, and magnesium sulfate group, with 8 rabbits in each group. Immediately after operation, the distilled water group and the magnesium sulfate group were injected with 0.5 mL distilled water and 20 mmol/L magnesium sulfate solution in the joint cavity 3 times a week for 4 weeks, respectively. The PTOA group was not treated. The general condition of the animals was observed after operation. After 4 weeks, the expressions of tumor necrosis factor α (TNF-α) and collagen typeⅡ in the joint fluid and the expression of collagen type Ⅱ in venous blood were detected by ELISA assay. The protein expressions of transient receptor potential channel vanilloid 5 (TRPV5) and microtubule associated protein 1 light chain 3 (LC3; LC3-Ⅱ/LC3-Ⅰ) in femoral cartilage were detected by Western blot. The mRNA expressions of interleukin 1β (IL-1β), TNF-α, matrix metalloproteinases 3 (MMP-3) in synovial tissue and collagen type Ⅱ, Aggrecan (AGN), SOX9 in cartilage tissue were detected by real-time fluorescence quantitative PCR. Cartilage tissue sections were stained with HE staining, Masson staining, and Alcian blue staining and scored according to the modified histological osteoarthritis (OA) score.

Results

All animals survived until the experiment was completed. Compared with the other two groups, the expression of TNF-α in joint effusion and collagen type Ⅱ in joint effusion and venous blood were decreased in magnesium sulfate group; the protein expression of TRPV5 decreased, and the ratio of LC3-Ⅱ/LC3-Ⅰ increased significantly; the mRNA expressions of IL-1β, TNF-α, and MMP-3 in synovial tissue were decreased, and the mRNA expressions of collagen type Ⅱ, AGN, and SOX9 in cartilage tissue were increased; OA scores also decreased significantly. All differences were statistically significant ( P<0.05). There was no significant difference in the above indicators between the PTOA group and the distilled water group ( P>0.05).

Conclusion

Intra-articular injection of magnesium sulfate can reduce intra-articular inflammation, reduce the loss of collagen type Ⅱ and AGN, and is beneficial to cartilage regeneration in rabbits. The mechanism may be related to the initiation of chondroautophagy by inhibiting the calcium channel TRPV5.

Melatonin Rescues Mesenchymal Stem Cells from Senescence Induced by the Uremic Toxin p-Cresol via Inhibiting mTOR-Dependent Autophagy

p-Cresol, found at high concentrations in the serum of chronic kidney failure patients, is known to cause cell senescence and other complications in different parts of the body. p-Cresol is thought to mediate cytotoxic effects through the induction of autophagy response. However, toxic effects of p-cresol on mesenchymal stem cells have not been elucidated. Thus, we aimed to investigate whether p-cresol induces senescence of mesenchymal stem cells, and whether melatonin can ameliorate abnormal autophagy response caused by p-cresol. We found that p-cresol concentration-dependently reduced proliferation of mesenchymal stem cells. Pretreatment with melatonin prevented pro-senescence effects of p-cresol on mesenchymal stem cells. We found that by inducing phosphorylation of Akt and activating the Akt signaling pathway, melatonin enhanced catalase activity and thereby inhibited the accumulation of reactive oxygen species induced by p-cresol in mesenchymal stem cells, ultimately preventing abnormal activation of autophagy. Furthermore, preincubation with melatonin counteracted other pro-senescence changes caused by p-cresol, such as the increase in total 5′-AMP-activated protein kinase expression and decrease in the level of phosphorylated mechanistic target of rapamycin. Ultimately, we discovered that melatonin restored the expression of senescence marker protein 30, which is normally suppressed because of the induction of the autophagy pathway in chronic kidney failure patients by p-cresol. Our findings suggest that stem cell senescence in patients with chronic kidney failure could be potentially rescued by the administration of melatonin, which grants this hormone a novel therapeutic role.

Doxorubicin combined with low intensity ultrasound suppresses the growth of oral squamous cell carcinoma in culture and in xenografts

Background

Oral squamous cell carcinoma (OSCC) invades surrounding tissues by upregulating matrix metalloproteinases (MMPs) -2 and −9, which causes over-expression of the Hedgehog signaling proteins Shh and Gli-1 and degradation of the extracellular matrix, thereby creating a “highway” for tumor invasion. We explored the potential of low intensity ultrasound (LIUS) and doxorubicin (DOX) to inhibit the formation of this “highway”.

Methods

MTT assays were used to examine OSCC cell viability after exposure to LIUS and DOX. The cell morphological changes and ultrastructure were detected by scanning electron microscopy and transmission electron microscopy. Endogenous autophagy-associated proteins were analyzed by immunofluorescent staining and western blotting. Cell migration and invasion abilities were evaluated by Transwell assays. Collagen fiber changes were evaluated by Masson’s trichrome staining. Invasion-associated proteins were analyzed by immunohistochemistry and western blotting.

Results

LIUS of 1 W/cm² increased the in vitro DOX uptake into OSCC by nearly 3-fold in three different cell lines and induced transient autophagic vacuoles on the cell surface. The combination of LIUS and 0.2 μg/ml DOX inhibited tumor cell viability and invasion, promoted tumor stromal collagen deposition, and prolonged the survival of mice. This combination also down-regulated MMP-2, MMP-9, Shh and Gli-1 in tumor xenografts. Collagen fiber expression was negatively correlated with the expression of these proteins in human OSCC samples.

Conclusions

Our findings suggest that effective low dosages of DOX in combination with LIUS can inhibit cell proliferation, migration and invasion, which might be through MMP-2/9 production mediated by the Hedgehog signaling pathway.

Electronic supplementary material

The online version of this article (10.1186/s13046-017-0633-y) contains supplementary material, which is available to authorized users.

Valproic Acid Induces Endocytosis-Mediated Doxorubicin Internalization and Shows Synergistic Cytotoxic Effects in Hepatocellular Carcinoma Cells

Valproic acid (VPA), a well-known histone deacetylase (HDAC) inhibitor, is used as an anti-cancer drug for various cancers, but the synergistic anti-cancer effect of VPA and doxorubicin (DOX) combination treatment and its potential underlying mechanism in hepatocellular carcinoma (HCC) remain to be elucidated. Here, we evaluate the mono- and combination-therapy effects of VPA and DOX in HCC and identify a specific and efficient, synergistic anti-proliferative effect of the VPA and DOX combination in HCC cells, especially HepG2 cells; this effect was not apparent in MIHA cells, a normal hepatocyte cell line. The calculation of the coefficient of drug interaction confirmed the significant synergistic effect of the combination treatment. Concurrently, the synergistic apoptotic cell death caused by the VPA and DOX combination treatment was confirmed by Hoechst nuclear staining and Western blot analysis of caspase-3 and poly (ADP-ribose) polymerase (PARP) activation. Co-treatment with VPA and DOX enhanced reactive oxygen species (ROS) generation and autophagy, which were clearly attenuated by ROS and autophagy inhibitors, respectively. Furthermore, as an indication of the mechanism underlying the synergistic effect, we observed that DOX internalization, which was induced in the VPA and DOX combination-treated group, occurred via by the caveolae-mediated endocytosis pathway. Taken together, our study uncovered the potential effect of the VPA and DOX combination treatment with regard to cell death, including induction of cellular ROS, autophagy, and the caveolae-mediated endocytosis pathway. Therefore, these results present novel implications in drug delivery research for the treatment of HCC.