The new cardioprotector Monohydroxyethylrutoside protects against doxorubicin-induced inflammatory effects in vitro

An integrative review of nonobvious puzzles of cellular and molecular cardiooncology

Oncologic patients are subjected to four major treatment types: surgery, radiotherapy, chemotherapy, and immunotherapy. All nonsurgical forms of cancer management are known to potentially violate the structural and functional integrity of the cardiovascular system. The prevalence and severity of cardiotoxicity and vascular abnormalities led to the emergence of a clinical subdiscipline, called cardiooncology. This relatively new, but rapidly expanding area of knowledge, primarily focuses on clinical observations linking the adverse effects of cancer therapy with deteriorated quality of life of cancer survivors and their increased morbidity and mortality. Cellular and molecular determinants of these relations are far less understood, mainly because of several unsolved paths and contradicting findings in the literature. In this article, we provide a comprehensive view of the cellular and molecular etiology of cardiooncology. We pay particular attention to various intracellular processes that arise in cardiomyocytes, vascular endothelial cells, and smooth muscle cells treated in experimentally-controlled conditions in vitro and in vivo with ionizing radiation and drugs representing diverse modes of anti-cancer activity.

Endothelial dysfunction as a complication of anti-cancer therapy

Recent strides in anti-cancer therapeutics have improved longevity and led to a growing population of cancer survivors, who are increasingly likely to die of other causes. Treatment-induced cardiotoxicity is a complication of several therapeutic agents with acute and long-term consequences for cancer patients. Vascular endothelial dysfunction is a precursor and hallmark of ischemic coronary disease and may play a role in anti-cancer therapy-induced cardiotoxicity. This review summarizes clinical evidence for endothelial dysfunction following anti-cancer therapy and extends the discussion to include the impact of therapeutic agents on conduit arteries and the microcirculation. We highlight the role of innate immune system activation and cross-talk between inflammation and oxidative stress as pathogenic mechanisms underlying anti-cancer therapy-induced vascular toxicity. Understanding the impact of anti-cancer agents on the vascular endothelium will inform therapeutic approaches to prevent or reverse treatment-induced cardiotoxicity and may serve as an important tool to predict, monitor, and prevent adverse cardiovascular outcomes in patients undergoing treatment.

Acylated ghrelin protects against doxorubicin-induced nephropathy by activating silent information regulator 1

This study investigated the nephroprotective role of acylated ghrelin (AG) against DOX-induced nephropathy and examined whether the protection involves silent information regulator 1 (SIRT1). Rats were divided into control, control + AG, DOX, DOX + AG, DOX + AG + [D-Lys3]-GHRP-6 (a ghrelin receptor antagonist), and DOX + AG + EX-527 (a sirt1 inhibitor). DOX was given over the first 2 weeks. AG (10 ng/kg) and both inhibitors were given as 3 doses/wk for 5 weeks. AG improved the structure and the function of the kidneys; down-regulated the renal expression of TGF-β1, collagen 1A1 and α-SMA; and inhibited the renal collagen deposition in the kidneys of DOX-treated rats. Concomitantly, it reduced the renal levels of ROS, MDA, TNF-α, and IL-6 and protein levels of cytochrome-c, TGF-β1, Smad3 and α-SMA in these rats. In both the control and DOX-treated rats, AG significantly increased the renal levels of SOD and GSH, decreased the expression of cleaved caspase-3 and Bax, increased the total levels and the nuclear activity of SIRT1 and reduced the deacetylation of p53, NF-κB and FOXO-31. All the effects were abolished by the concurrent administration of EX-527 and [D-Lys3]-GHRP-6. In conclusion, AG prevents DOX-induced nephropathy in SIRT1 and GSHRa1-dependent mechanism.

Glomerular Endothelial Cells as Instigators of Glomerular Sclerotic Diseases

Glomerular endothelial cell (GEnC) dysfunction is important in the pathogenesis of glomerular sclerotic diseases, including Focal Segmental Glomerulosclerosis (FSGS) and overt diabetic nephropathy (DN). GEnCs form the first cellular barrier in direct contact with cells and factors circulating in the blood. Disturbances in these circulating factors can induce GEnC dysfunction. GEnC dysfunction occurs in early stages of FSGS and DN, and is characterized by a compromised endothelial glycocalyx, an inflammatory phenotype, mitochondrial damage and oxidative stress, aberrant cell signaling, and endothelial-to-mesenchymal transition (EndMT). GEnCs are in an interdependent relationship with podocytes and mesangial cells, which involves bidirectional cross-talk via intercellular signaling. Given that GEnC behavior directly influences podocyte function, it is conceivable that GEnC dysfunction may culminate in podocyte damage, proteinuria, subsequent mesangial activation, and ultimately glomerulosclerosis. Indeed, GEnC dysfunction is sufficient to cause podocyte injury, proteinuria and activation of mesangial cells. Aberrant gene expression patterns largely contribute to GEnC dysfunction and epigenetic changes seem to be involved in causing aberrant transcription. This review summarizes literature that uncovers the importance of cross-talk between GEnCs and podocytes, and GEnCs and mesangial cells in the context of the development of FSGS and DN, and the potential use of GEnCs as efficacious cellular target to pharmacologically halt development and progression of DN and FSGS.

Human Pluripotent Stem Cell-Derived Cardiomyocytes for Assessment of Anticancer Drug-Induced Cardiotoxicity

Cardiotoxicity is a major cause of high attrition rates among newly developed drugs. Moreover, anti-cancer treatment-induced cardiotoxicity is one of the leading reasons of mortality in cancer survivors. Cardiotoxicity screening in vitro may improve predictivity of cardiotoxicity by novel drugs, using human pluripotent stem cell (hPSC)-derived-cardiomyocytes. Anthracyclines, including Doxorubicin, are widely used and highly effective chemotherapeutic agents for the treatment of different forms of malignancies. Unfortunately, anthracyclines cause many cardiac complications early or late after therapy. Anthracyclines exhibit their potent anti-cancer effect primarily via induction of DNA damage during the DNA replication phase in proliferative cells. In contrast, studies in animals and hPSC-cardiomyocytes have revealed that cardiotoxic effects particularly arise from (1) the generation of oxidative stress inducing mitochondrial dysfunction, (2) disruption of calcium homeostasis, and (3) changes in transcriptome and proteome, triggering apoptotic cell death. To increase the therapeutic index of chemotherapeutic Doxorubicin therapy several protective strategies have been developed or are under development, such as (1) reducing toxicity through modification of Doxorubicin (analogs), (2) targeted delivery of anthracyclines specifically to the tumor tissue or (3) cardioprotective agents that can be used in combination with Doxorubicin. Despite continuous progress in the field of cardio-oncology, cardiotoxicity is still one of the major complications of anti-cancer therapy. In this review, we focus on current hPSC-cardiomyocyte models for assessing anthracycline-induced cardiotoxicity and strategies for cardioprotection. In addition, we discuss latest developments toward personalized advanced pre-clinical models that are more closely recapitulating the human heart, which are necessary to support in vitro screening platforms with higher predictivity. These advanced models have the potential to reduce the time from bench-to-bedside of novel antineoplastic drugs with reduced cardiotoxicity.

Protection from doxorubicin-induced nephrotoxicity by clindamycin: novel antioxidant, anti-inflammatory and anti-apoptotic roles

This study was performed to examine whether clindamycin could protect against doxorubicin (DOX)-induced acute nephrotoxicity, and if so, what molecular mechanisms responsible for this protective effect. Male albino rats were pretreated with clindamycin once per day for 5 consecutive days at a dose of 300 mg/kg, i.p, then received a single dose of DOX (15 mg/kg; i.p) on the 5th day. DOX-induced marked renal injury as indicated by the presence of inflammatory cell infiltration, congestion, and edema accompanied by elevation in serum levels of creatinine and urea. These effects were alleviated by clindamycin pretreatment. DOX caused glutathione depletion and reduction in level of the antioxidant enzyme, catalase. Pretreatment with clindamycin markedly prohibited DOX-induced oxidative damage in renal tissue. Moreover, DOX provoked inflammatory responses in renal tissues as confirmed by increased expressions of NF-κB and COX-2 which were significantly reduced by clindamycin pretreatment. Besides, DOX-triggered apoptotic cascades in renal tissues as evidenced by elevated expression of pro-apoptotic proteins; Bax and cytochrome c, enhancing activity of caspase-3 enzyme whereas reducing the expression of anti-apoptotic Bcl-2 protein. Clindamycin pretreatment counteracts these apoptotic effects of DOX. Summarily, our results provide an evidence for the first time that clindamycin has a potential protective action against DOX-induced acute nephrotoxicity through inhibiting oxidative stress, inflammatory cascades, and apoptotic tissue injury.

Aldose reductase inhibitor, fidarestat prevents doxorubicin-induced endothelial cell death and dysfunction

Despite doxorubicin (Dox) being one of the most widely used chemotherapy agents for breast, blood and lung cancers, its use in colon cancer is limited due to increased drug resistance and severe cardiotoxic side effects that increase mortality associated with its use at high doses. Therefore, better adjuvant therapies are warranted to improve the chemotherapeutic efficacy and to decrease cardiotoxicity. We have recently shown that aldose reductase inhibitor, fidarestat, increases the Dox-induced colon cancer cell death and reduces cardiomyopathy. However, the efficacy of fidarestat in the prevention of Dox-induced endothelial dysfunction, a pathological event critical to cardiovascular complications, is not known. Here, we have examined the effect of fidarestat on Dox-induced endothelial cell toxicity and dysfunction in vitro and in vivo. Incubation of human umbilical vein endothelial cells (HUVECs) with Dox significantly increased the endothelial cell death, and pre-treatment of fidarestat prevented it. Further, fidarestat prevented the Dox-induced oxidative stress, formation of reactive oxygen species (ROS) and activation of Caspase-3 in HUVECs. Fidarestat also prevented Dox-induced monocyte adhesion to HUVECs and expression of ICAM-1 and VCAM-1. Fidarestat pre-treatment to HUVECs restored the Dox-induced decrease in the Nitric Oxide (NO)-levels and eNOS expression. Treatment of HUVECs with Dox caused a significant increase in the activation of NF-κB and expression of various inflammatory cytokines and chemokines which were prevented by fidarestat pre-treatment. Most importantly, fidarestat prevented the Dox-induced mouse cardiac cell hypertrophy and expression of eNOS, iNOS, and 3-Nitrotyrosine in the aorta tissues. Further, fidarestat blunted the Dox-induced expression of various inflammatory cytokines and chemokines in vivo. Thus, our results suggest that by preventing Dox-induced endothelial cytotoxicity and dysfunction, AR inhibitors could avert cardiotoxicity associated with anthracycline chemotherapy.

Aldose reductase inhibitor increases doxorubicin-sensitivity of colon cancer cells and decreases cardiotoxicity

Anthracycline drugs such as doxorubicin (DOX) and daunorubicin remain some of the most active wide-spectrum and cost-effective drugs in cancer therapy. However, colorectal cancer (CRC) cells are inherently resistant to anthracyclines which at higher doses cause cardiotoxicity. Our recent studies indicate that aldose reductase (AR) inhibitors such as fidarestat inhibit CRC growth in vitro and in vivo. Here, we show that treatment of CRC cells with fidarestat increases the efficacy of DOX-induced death in HT-29 and SW480 cells and in nude mice xenografts. AR inhibition also results in higher intracellular accumulation of DOX and decreases the expression of drug transporter proteins MDR1, MRP1, and ABCG2. Further, fidarestat also inhibits DOX-induced increase in troponin-I and various inflammatory markers in the serum and heart and restores cardiac function in mice. These results suggest that fidarestat could be used as adjuvant therapy to enhance DOX sensitivity of CRC cells and to reduce DOX-associated cardiotoxicity.

Cardioprotective mechanisms of phytochemicals against doxorubicin-induced cardiotoxicity

Doxorubicin (DOX) is an anthracycline antibiotic, which is effectively used in the treatment of different malignancies, such as leukemias and lymphomas. Its most serious side effect is dose-dependent cardiotoxicity, which occurs through inducing oxidative stress apoptosis. Due to the myelosuppressive effect of dexrazoxane, a commonly-used drug to alleviate DOX-induced cardiotoxicity, researchers investigated the potential of phytochemicals for prophylaxis and treatment of this condition. Phytochemicals are plant chemicals that have protective or disease preventive properties. Preclinical trials have shown antioxidant properties for several plant extracts, such as those of Aerva lanata, Aronia melanocarpa, Astragalus polysaccharide, and Bombyx mori plants. Other plant extracts showed an ability to inhibit apoptosis, such as those of Astragalus polysaccharide, Azadirachta indica, Bombyx mori, and Allium stavium plants. Unlike synthetic agents, phytochemicals do not impair the clinical activity of DOX and they are particularly safe for long-term use. In this review, we summarized the results of preclinical trials that investigated the cardioprotective effects of phytochemicals against DOX-induced cardiotoxicity. Future human trials are required to translate these cardioprotective mechanisms into practical clinical implications.

The Protective Role of Phenolic Compounds Against Doxorubicin-induced Cardiotoxicity: A Comprehensive Review

Although doxorubicin (DOX) is among the most widely used anticancer agents, its clinical application is hampered owing to its cardiotoxicity. Adjuvant therapy with an antioxidant has been suggested as a promising strategy to reduce DOX-induced adverse effects. In this context, many phenolic compounds have been reported to protect against DOX-induced cardiotoxicity. The cardioprotective effects of phenolic compounds are exerted via multiple mechanisms including inhibition of reactive oxygen species generation, apoptosis, NF-κB, p53, mitochondrial dysfunction, and DNA damage. In this review, we present a summary of the in vitro, in vivo, and clinical findings on the protective mechanisms of phenolic compounds against DOX-induced cardiotoxicity.

Complex of C60 Fullerene with Doxorubicin as a Promising Agent in Antitumor Therapy

The main aim of this work was to evaluate the effect of doxorubicin in complex with C60 fullerene (C60 + Dox) on the growth and metastasis of Lewis lung carcinoma in mice and to perform a primary screening of the potential mechanisms of C60 + Dox complex action. We found that volume of tumor from mice treated with the C60 + Dox complex was 1.4 times less than that in control untreated animals. The number of metastatic foci in lungs of animals treated with C60 + Dox complex was two times less than that in control untreated animals. Western blot analysis of tumor lysates revealed a significant decrease in the level of heat-shock protein 70 in animals treated with C60 + Dox complex. Moreover, the treatment of tumor-bearing mice was accompanied by the increase of cytotoxic activity of immune cells. Thus, the potential mechanisms of antitumor effect of C60 + Dox complex include both its direct action on tumor cells by inducing cell death and increasing of stress sensitivity and an immunomodulating effect. The obtained results provide a scientific basis for further application of C60 + Dox nanocomplexes as treatment agents in cancer chemotherapy.

Ginsenoside Rg3 antagonizes adriamycin-induced cardiotoxicity by improving endothelial dysfunction from oxidative stress via upregulating the Nrf2-ARE pathway through the activation of akt

BACKGROUND

Adriamycin (ADM) is an antineoplastic agent that is effective against a wide range of cancers, but cardiac toxicity limits its clinical application. Ginsenoside Rg3 (Rg3), an anti-cancer active ingredient of Panax ginseng, was reported to have anti-oxidative, anti-apoptotic, and cardioprotective properties.

PURPOSE

The current study aimed to investigate the possible protective effect of Rg3 against ADM-induced cardiotoxicity.

STUDY DESIGN

The activity of Rg3 to improve endothelial dysfunction was processed both in vivo and in vitro.

METHODS

We investigated the cardioprotective effect of Rg3 on ADM treated rats by echocardiography. The endothelial dysfunction was assessed using an aortic ring assay. Cardiac microvascular endothelial cells were cultured to investigate the effects of Rg3 on ADM-treated cells.

RESULTS

Results showed that Rg3 could ameliorate the decrease in the ejection fraction and fractional shortening that was induced by ADM, and improve the left ventricular outflow. The aortic ring assay showed that Rg3 could partially recover the abnormal vascular function. In vitro studies showed that Rg3 could promote cell viability to attenuate ADM induced oxidative damage and apoptosis. This counteraction was achieved partially via activation of the Nrf2-ARE pathway through the activation of Akt.

CONCLUSION

These findings elucidated the potential of Rg3 as a promising reagent for treating ADM-induced cardiotoxicity in clinic.

Induction of inflammatory cytokines and alteration of urothelial ATP, acetylcholine and prostaglandin E2 release by doxorubicin

Intravesical treatment with cytotoxic drugs such as doxorubicin is associated with local adverse effects in bladder cancer patients. Here we investigate the effects of doxorubicin on urothelial release of ATP, acetylcholine and prostaglandin E(2), and production of inflammatory cytokines. Urothelial cells were treated with doxorubicin for 1h at 37 °C. Immediately or 24 h following treatment the level of ATP, acetylcholine and prostaglandin E(2) released under basal and stimulated conditions was measured and compared to release from vehicle treated control cultures. The presence of inflammatory cytokines, in culture medium was also assessed 24 h after doxorubicin pre-treatment. Immediately following treatment, stimulated ATP release was inhibited at doxorubicin concentrations ≥1 μg/ml and showed partial recovery at 24 h. Immediately following treatment, basal acetylcholine release was increased by doxorubicin at its clinical concentration (1 mg/ml), while a concentration-dependent decrease in stimulated acetylcholine release was observed. Twenty four hour after treatment, basal acetylcholine release was increased in culture treated with 0.01 mg/ml doxorubicin while stimulated acetylcholine release remained depressed. A significant increase in prostaglandin E(2) release was observed in cells immediately and 24 h after treatment with doxorubicin. A 5.5- and 2-fold increase in interleukin -8 and -1β secretion, respectively was detected 24 h following doxorubicin treatment. These findings indicate that inflammatory cytokines interleukin-8 and -1β are induced and urothelial mediator release is affected by treatment with doxorubicin at clinically relevant concentrations and durations of treatment. These changes may play a role in the adverse effects associated with intravesical doxorubicin treatment.

The influence of dexamethasone administration on the protection against doxorubicin-induced cardiotoxicity in purified embryonic stem cell-derived cardiomyocytes

Embryonic stem cells (ESCs) have various uses in drug toxicity, as they can be easily differentiated in vitro. However, one of the major obstacles in the assessment of these differentiated cells is the presence of a heterogeneous cell population. To circumvent this problem, purified ESC-derived desired cells by means of the tissue-specific GFP and/or antibiotic resistance gene expression has been proposed. Therefore, this study aimed to assess the role of doxorubicin (DOX) in cardiotoxicity by using genetically engineered purified ESC-derived cardiomyocytes under the control alpha-myosin heavy chain promoter. The results revealed that ESCs are suitable for evaluation of DOX cardiotoxicity. This study showed that DOX cardiotoxicity was reduced as detected by beating cardiomyocytes and caspase activity only by pretreatment with dexamethasone (DEX), not during or post-DOX treatment. DEX influence appears to be mediated via glucocorticoid receptor and enhances cardiomyocyte-specific gene expression. Therefore, for the general assessment of cytotoxicity, non-genetically engineered ESC-derived cardiomyocytes are sufficient but for the molecular assessment of DOX-induced toxicity, genetically engineered purified ESC-derived cardiomyocytes are necessary.

Carvedilol Attenuates Inflammatory-Mediated Cardiotoxicity in Daunorubicin-Induced Rats

Cardiotoxicity, which results from intense cardiac oxidative stress and inflammation, is the main limiting factor of the anthracyclines. Carvedilol, a beta blocker that is used as a multifunctional neurohormonal antagonist, has been shown to act not only as an anti-oxidant, but also as an anti-inflammatory drug. This study was designed to evaluate whether carvedilol exerts a protective role against inflammation-mediated cardiotoxicity in the daunorubicin (DNR)-induced rats. Carvedilol was administered orally to the rats every day for 6 weeks at a cumulative dose of 9 mg/kg body weight DNR. DNR significantly induced cardiac damage and worsened cardiac function as well as increased cardiac mast cell density, elevating the myocardial protein and mRNA expression levels of tumor necrosis factor-α, vascular cell adhesion molecule-1, inter-cellular adhesion molecule-1, nuclear factor kappa-B, cyclooxygenase-2, monocyte chemotactic protein -1 and interleukin -6 compared to that in the control group. Cotreatment with carvedilol significantly attenuated the myocardial protein and mRNA expression levels of these inflammatory markers, decreased cardiac mast cell density, improved histological cardiac damage and cardiac functions. In conclusion, inflammation plays a significant role in DNR-induced cardiotoxicity, and carvedilol contributes to cardioprotection against inflammation-mediated cardiotoxicity in DNR-induced rats through its anti-inflammatory mechanism.

Low-temperature 1H-NMR spectroscopic study of doxorubicin influence on the hydrated properties of nanosilica modified by DNA

The effect of the anticancer drug--doxorubicin (Dox) on hydration properties of a nanocomposite material deposited on silica and modified by small amount of DNA (0.6 wt%) was studied by means of (1)H NMR spectroscopy at low temperatures (in the range of 200-280 K). Signals of either weakly (WAW) or strongly (SAW) associated water, as well as water associated with electrondonor groups of the composite surface (ASW), were observed. The findings reveal that, depending on the temperature and the composition of the dispersion medium, fast molecular exchange takes place between different forms of interphase water. The presence of Dox (0.1-0.2 wt%) in the dispersion medium leads to change of the relative concentrations of different forms of water.

Doxorubicin selectively suppresses mRNA expression and production of endothelin-1 in endothelial cells

Doxorubicin (DXR) is a widely used cytostatic agent, but its administration is limited by its cardiovascular side effects. The endothelium is one of the largest organs in the human body and due to its direct contact with blood; it is exposed to the toxic effects of DXR. The aim of this study was to investigate in endothelial cells the effects of DXR on the expression of genes involved in cardiovascular diseases. We used in vitro cultured human umbilical vein endothelial cells (HUVEC) as a model; gene expression was assessed by SuperArray and qPCR. Out of the 96 representative genes of cardiovascular importance, the expression of only the ET-1 gene changed significantly. ET-1 mRNA expression was 10.9% of the untreated control (p=0.0049). This result was confirmed by qPCR (2.41% of control, p=0.0022). DXR also suppressed ET-1 production at protein level (p=0.0116). Both the early decrease in endothelial ET-1 production in the presence of DXR and the high plasma level of DXR during chemotherapy may influence the toxic effects of the drug.

New advances in molecular mechanisms and the prevention of adriamycin toxicity by antioxidant nutrients

Anthracyclines (doxorubicin, daunorubicin, epirubicin, and idarubicin) are currently the most effective group of anti-neoplastic drugs used in clinical practice. Of these, doxorubicin (also called adriamycin) is a key chemotherapeutic agent in cancer treatment, although its use is limited as a consequence of the chronic and acute toxicity associated with this drug. The molecular mechanisms of doxorubicin account for both the anti-cancer and the toxic side effects. Many antioxidants have been assayed, with positive or negative results, to prevent the toxicity of doxorubicin. The present review has two main goals: (1) to report the latest findings regarding the molecular mechanisms of doxorubicin toxicity; (2) to update our understanding of the role of natural antioxidants in preventive therapy against doxorubicin-induced toxicity. This review provides new evidence for the chemoprevention of doxorubicin toxicity, making use of natural antioxidants - in particular vitamin E, vitamin C, coenzyme Q, carotenoids, vitamin A, flavonoids, polyphenol, resveratrol, antioxidant from virgin olive oil and selenium - and offers new insights into the molecular mechanisms of doxorubicin toxicity with respect to DNA damage, free radicals and other parameters.

Characterization of the glutathione conjugate of the semisynthetic flavonoid monoHER

Flavonoids protect against oxidative stress by scavenging free radicals. During this protection flavonoids are oxidized. The oxidized flavonoids formed are often reactive. Consequently, protection by flavonoids can result in the formation of toxic products. In this study the oxidation of 7-mono-O-(beta-hydroxyethyl)rutoside (monoHER), which is a constituent of the registered drug Venoruton, was studied in the absence and presence of glutathione (GSH). MonoHER was oxidized by horseradish peroxidase/H(2)O(2). Spectrophotometric and HPLC analysis showed that in the presence of GSH, a monoHER-GSH conjugate was formed, which was identified as 2'-glutathionyl monohydroxyethylrutoside by mass spectrometric analysis and (1)H NMR. Preferential formation of this glutathione adduct in the B ring at C2' was confirmed by molecular quantum chemical calculations. This conjugate was also detected in the bile fluid of a healthy volunteer after iv administration of monoHER, demonstrating its formation in vivo. These results indicate that in the process of offering protection against free radicals, monoHER is converted into an oxidation product that is reactive toward thiols. The formation of this thiol-reactive oxidation product is potentially harmful. Thus, the supposed beneficial effect of monoHER as an antioxidant may be accompanied by the formation of products with an electrophilic, toxic potential.

TRAIL therapy in non-small cell lung cancer cells: sensitization to death receptor-mediated apoptosis by proteasome inhibitor bortezomib

Activation of the tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) receptor pathway is a promising therapeutic strategy to selectively eradicate cancer cells, including non-small cell lung cancer (NSCLC) cells. Recombinant human (rh) TRAIL/Apo-2L, a TRAIL-encoding adenovirus, and monoclonal antibodies directed against TRAIL receptors R1 and R2 were used to study cytotoxicity of TRAIL therapy in NSCLC cells. NSCLC cells showed differential sensitivity to TRAIL therapy, regardless of the agent used. Combination treatment of bortezomib and rhTRAIL led to synergistic apoptosis induction in NSCLC cell lines. Enhancement of rhTRAIL-induced apoptosis by bortezomib was caspase dependent, implicating extrinsic as well as intrinsic apoptosis activation, as shown by increased processing of caspase-8 as well as caspase-9, and could be abrogated completely by overexpression of caspase-8 inhibitor cytokine response modifier A (CrmA), and partially by overexpression of Bcl-2. Enhanced surface expression of TRAIL-R2, but also TRAIL-R1, was associated with bortezomib treatment, which is likely to contribute to the increased processing of caspase-8 in the combination treatment. Furthermore, TRAIL-induced activation of prosurvival transcription factor nuclear factor-kappaB was prevented by cotreatment with bortezomib, which may contribute to the observed synergistic apoptosis induction. Our preclinical data indicate that combination therapy of TRAIL and bortezomib may be an effective strategy for NSCLC.

Protection by flavonoids against anthracycline cardiotoxicity: from chemistry to clinical trials

Cardiotoxic side-effects of doxorubicin limit the clinical use of this anti-cancer agent. Iron chelators have been studied as protectors against doxorubicin-induced cardiotoxicity. These iron chelators do not provide optimal protection and have certain drawbacks. We therefore looked for new protectors and decided that these new compounds should combine iron chelating and antioxidant activity. Flavonoids appeared to possess those combined iron chelating and antioxidant properties. Quantum chemical evaluation of radical stabilization and determination of physico-chemical properties of a series of flavonoids brought our attention to the semi-synthetic flavonoid 7-monohydroxyetylrutoside (monoHER). Both in vitro (using an electrically paced mouse left atrium model) and in vivo (using a mouse ECG telemetry model) experiments corroborated the protective effect of monoHER. MonoHER also showed anti-inflammatory properties. A subsequent clinical phase I study showed that an i.v. dose of 1,500mg/m2 is a feasible and safe dose to be evaluated in a phase II study to investigate the protective properties of monoHER against doxorubicin-induced cardiotoxicity in cancer patients.

Caspase-dependent and -independent suppression of apoptosis by monoHER in Doxorubicin treated cells

Doxorubicin (DOX) is an antitumour agent for different types of cancer, but the dose-related cardiotoxicity limits its clinical use. To prevent this side effect we have developed the flavonoid monohydroxyethylrutoside (monoHER), a promising protective agent, which did not interfere with the antitumour activity of DOX. To obtain more insight in the mechanism underlying the selective protective effects of monoHER, we investigated whether monoHER (1 mM) affects DOX-induced apoptosis in neonatal rat cardiac myocytes (NeRCaMs), human endothelial cells (HUVECs) and the ovarian cancer cell lines A2780 and OVCAR-3. DOX-induced cell death was effectively reduced by monoHER in heart, endothelial and A2780 cells. OVCAR-3 cells were highly resistant to DOX-induced apoptosis. Experiments with the caspase-inhibitor zVAD-fmk showed that DOX-induced apoptosis was caspase-dependent in HUVECs and A2780 cells, whereas caspase-independent mechanisms seem to be important in NeRCaMs. MonoHER suppressed DOX-dependent activation of the mitochondrial apoptotic pathway in normal and A2780 cells as illustrated by p53 accumulation and activation of caspase-9 and -3 cleavage. Thus, monoHER acts by suppressing the activation of molecular mechanisms that mediate either caspase-dependent or -independent cell death. In light of the current work and our previous studies, the use of clinically achievable concentrations of monoHER has no influence on the antitumour activity of DOX whereas higher concentrations as used in the present study could influence the antitumour activity of DOX.

Anti-inflammatory agents and monoHER protect against DOX-induced cardiotoxicity and accumulation of CML in mice

Cardiac damage is the major limiting factor for the clinical use of doxorubicin (DOX). Preclinical studies indicate that inflammatory effects may be involved in DOX-induced cardiotoxicity. N^ε-(carboxymethyl) lysine (CML) is suggested to be generated subsequent to oxidative stress, including inflammation. Therefore, the aim of this study was to investigate whether CML increased in the heart after DOX and whether anti-inflammatory agents reduced this effect in addition to their possible protection on DOX-induced cardiotoxicity. These effects were compared with those of the potential cardioprotector 7-monohydroxyethylrutoside (monoHER).

BALB/c mice were treated with saline, DOX alone or DOX preceded by ketoprofen (KP), dexamethasone (DEX) or monoHER. Cardiac damage was evaluated according to Billingham. N^ε-(carboxymethyl) lysine was quantified immunohistochemically.

Compared to saline, a 21.6-fold increase of damaged cardiomyocytes was observed in mice treated with DOX (P<0.001). Addition of KP, DEX or monoHER before DOX significantly reduced the mean ratio of abnormal cardiomyocytes in comparison to mice treated with DOX alone (P⩽0.02). In addition, DOX induced a significant increase in the number of CML-stained intramyocardial vessels per mm² (P=0.001) and also in the intensity of CML staining (P=0.001) compared with the saline-treated group. N^ε-(carboxymethyl) lysine positivity was significantly reduced (P⩽0.01) by DOX-DEX, DOX-KP and DOX-monoHER. These results confirm that inflammation plays a role in DOX-induced cardiotoxicity, which is strengthened by the observed DOX-induced accumulation of CML, which can be reduced by anti-inflammatory agents and monoHER.

Protectors against doxorubicin-induced cardiotoxicity: Flavonoids

Doxorubicin is a widely used anthracycline anticancer agent. Its use may cause cardiomyopathy: in fact, the development of cumulative dose-related cardiotoxicity forms the major limitation of clinical doxorubicin use. We therefore searched for protective agents that combine iron-chelating and oxygen radical-scavenging properties. Moreover, any novel protector should not interfere with the cytostatic activity of doxorubicin. After extensive in vitro screening we found that flavonoids could serve this purpose. In particular 7-monohydroxyethylrutoside almost completely protected against the negative inotropic action of doxorubicin in the electrically paced mouse left atrium model. In vivo it gave full protection at 500 mg/kg intraperitoneally against the doxorubicin-induced ST-interval lengthening in the ECG. Moreover, this protector did not influence the antitumor effect of doxorubicin either in vitro using the human ovarian cell lines A2780 and OVCAR-3 and the human breast cancer cell line MCF-7 or in vivo in A2780 and OVCAR-3 subcutaneous xenografts in nude mice. Comparison of various iron chelators suggest that iron, in contrast to the general assumption, might not play a crucial role in the oxidative stress-induced toxicity of doxorubicin. Moreover, incubation of vascular endothelial cells with doxorubicin produced overexpression of adhesion molecules, which could be inhibited by 7-monohydroxyethylrutoside. From a study in human volunteers, we conclude that an intravenous dose of 1500 mg/m(2) of 7-monohydroxyethylrutoside is feasible and is safe to be investigated as protection against doxorubicin-induced cardiotoxicity.

Iron is not involved in oxidative stress-mediated cytotoxicity of doxorubicin and bleomycin

BACKGROUND AND PURPOSE

The anticancer drugs doxorubicin and bleomycin are well-known for their oxidative stress-mediated side effects in heart and lung, respectively. It is frequently suggested that iron is involved in doxorubicin and bleomycin toxicity. We set out to elucidate whether iron chelation prevents the oxidative stress-mediated toxicity of doxorubicin and bleomycin and whether it affects their antiproliferative/proapoptotic effects.

EXPERIMENTAL APPROACH

Cell culture experiments were performed in A549 cells. Formation of hydroxyl radicals was measured in vitro by electron paramagnetic resonance (EPR). We investigated interactions between five iron chelators and the oxidative stress-inducing agents (doxorubicin, bleomycin and H(2)O(2)) by quantifying oxidative stress and cellular damage as TBARS formation, glutathione (GSH) consumption and lactic dehydrogenase (LDH) leakage. The antitumour/proapoptotic effects of doxorubicin and bleomycin were assessed by cell proliferation and caspase-3 activity assay.

KEY RESULTS

All the tested chelators, except for monohydroxyethylrutoside (monoHER), prevented hydroxyl radical formation induced by H(2)O(2)/Fe(2+) in EPR studies. However, only salicylaldehyde isonicotinoyl hydrazone and deferoxamine protected intact A549 cells against H(2)O(2)/Fe(2+). Conversely, the chelators that decreased doxorubicin and bleomycin-induced oxidative stress and cellular damage (dexrazoxane, monoHER) were not able to protect against H(2)O(2)/Fe(2+).

CONCLUSIONS AND IMPLICATIONS

We have shown that the ability to chelate iron as such is not the sole determinant of a compound protecting against doxorubicin or bleomycin-induced cytotoxicity. Our data challenge the putative role of iron and hydroxyl radicals in the oxidative stress-mediated cytotoxicity of doxorubicin and bleomycin and have implications for the development of new compounds to protects against this toxicity.

Targeting tumor microvessels using doxorubicin encapsulated in a novel thermosensitive liposome

Liposomal drugs accumulate only in perivascular regions in tumors after i.v. injection. Thus, they cannot kill tumor cells in deeper tissue layers. To circumvent this problem, we investigated effects of doxorubicin (DOX) encapsulated in a lysolecithin-containing thermosensitive liposome (LTSL) on tumor microcirculation because damaging microvessels would stop nutrient supply to deeper tumor cells. We used LTSL-DOX in combination with hyperthermia to treat a human squamous carcinoma xenograft (FaDu) implanted in dorsal skinfold chambers in nude mice. Before the treatment, the RBC velocity in tumors was 0.428 ± 0.037 mm/s and the microvascular density was 3.93 ± 0.44 mm/mm2. At 24 hours after the treatment, they were reduced to 0.003 ± 0.003 mm/s and 0.86 ± 0.27 mm/mm2, respectively. The same treatment, however, caused only 32% decrease in the RBC velocity and no apparent change in microvascular networks in normal s.c. tissues over the same period. LTSL and LTSL-DOX alone had no effect on tumor microcirculation, and LTSL plus hyperthermia caused only a transient decrease in the RBC velocity in tumors. At 24 hours after treatments, tumor microcirculation in all these control experiments was insignificantly different from that before the treatments. We also examined apoptosis of cells in tumors at different time points after LTSL-DOX plus hyperthermia treatment and observed few apoptotic cells in tumor microvessels. In conclusion, the rapid release of DOX during hyperthermia could make the drug to shutdown tumor blood flow while have only minor effects on normal microcirculation in s.c. tissues.

Overexpression of Bcl2 abrogates chemo- and radiotherapy-induced sensitisation of NCI-H460 non-small-cell lung cancer cells to adenovirus-mediated expression of full-length TRAIL

TNF-related apoptosis-inducing ligand (TRAIL, also known as Apo-2L) is a promising novel anticancer agent that selectively induces apoptosis in tumour cells and the activity of which can be enhanced by combined treatment with chemo- or radiotherapy. For therapeutic purposes, the use of full-length TRAIL may be favourable to recombinant TRAIL based on its increased tumour cell killing potential, and the delivery of TRAIL at the tumour site by adenovirus vectors may provide an approach to overcome the short half-life of recombinant TRAIL and hepatocyte toxicity in vivo. Here, we constructed an adenoviral vector expressing full-length TRAIL (AdTRAIL) and studied the potential of chemo- and radiotherapy in enhancing AdTRAIL-induced apoptosis in non-small cell lung cancer (NSCLC) H460 cells and normal cells and, in addition, investigated the mechanism of AdTRAIL-induced apoptosis. AdTRAIL effectively killed H460 cells, which we previously showed to have a deficiency in mitochondria-dependent apoptosis by downstream activation of caspase-8 rather than caspase-9. Further analyses revealed that AdTRAIL induces death receptor- and mitochondria-dependent apoptosis that could be partially suppressed by Bcl2 overexpression. Combined treatment with doxorubicin (DOX), cisplatin (CDDP), paclitaxel (PTX) and radiation strongly enhanced AdTRAIL-induced cytotoxicity in a synergistic way. Synergy was accompanied by the cleavage of Bid and an increase in caspase-8 processing that was abolished by Bcl2 overexpression, indicating that the Bid-mitochondrial amplification loop is functional in H460 cells. Moreover, combination treatment did not alter the tumour selectivity of AdTRAIL since normal human fibroblasts (NHFs) remained resistant under these conditions. These findings further indicate that the combined use of chemo/radiotherapy and adenovirus-produced full-length TRAIL may provide a valuable treatment option for NSCLC.

Sustained protective effects of 7-monohydroxyethylrutoside in an in vivo model of cardiac ischemia–reperfusion

Earlier studies have shown that 7-monohydroxyethylrutoside (monoHER), an antioxidant flavonoid, protects against doxorubicin-induced cardiotoxicity. In this study, we investigated potential sustained cardioprotective effects of monoHER in a model of ischemia-reperfusion (I/R) in mice. Ischemia was induced for 30 min by ligating the left anterior descending coronary artery. Afterwards, the ligature was removed and reperfusion was allowed for 6 or 24 h or 2 weeks. MonoHER (500 mg/kg) was given intraperitoneally (i.p.) one hour before ischemia. Treatment with monoHER significantly attenuated myocardial neutrophil influx both at 6 and 24 h after reperfusion by 77% and 76%, respectively. Infarct size was also significantly reduced, 24 h and 2 weeks after reperfusion by 58% and 49%, respectively. Whereas ischemia-reperfusion had no influence on basal levels of cardiac contractility (+dp/dt), responses to dobutamine were blunted 24 h and 2 weeks after reperfusion. In mice treated with monoHER, cardiac contractility response was significantly restored. These results indicate that monoHER exerts a sustained cardioprotective effect on ischemia-reperfusion injury and prevents deterioration of cardiac contractility.