Doxorubicin Induces Apoptosis in Normal and Tumor Cells via Distinctly Different Mechanisms

Selenadiazole derivatives antagonize hyperglycemia-induced drug resistance in breast cancer cells by activation of AMPK pathways

Hyperglycemia is an important factor for chemoresistance of breast cancer patients with diabetes. In the present study, a novel selenadiazole derivative has been evaluated and found to be able to antagonize the doxorubicin (DOX) resistance of MCF-7 cells under simulated diabetes conditions. Hyperglycemia promotes the proliferation, invasion and migration of MCF-7 cells through activation of ERK and AKT pathways, which could be inhibited by the synthetic selenadiazole derivative. The antitumor effects of the selenadiazole derivative were attributed to its ability to activate AMPK pathways. Furthermore, the high lipophilicity (log P = 1.9) of the synthetic selenadiazole derivative facilitated its uptake by cancer cells and subsequently potentiated the cellular uptake of DOX, leading to a strong enhancment of the antiproliferative activity of DOX on MCF-7 cells by induction of apoptosis. The apoptosis was initiated by the ROS overproduction induced by the cooperation of the selenadiazole derivative and DOX. The excessive ROS then caused damage to DNA, which upregulated the expression of proapoptosis Bcl-2 family proteins and led to fragmentation of mitochondria, which finally caused apoptosis of the cancer cells. Taken together, this study provides a rational strategy for using selenadiazole derivatives to overcome hyperglycemia-induced drug resistance in breast cancer by activation of AMPK-mediated pathways.

Targeting tachykinin receptors in neuroblastoma

Neuroblastoma is the most common extracranial tumor in children. Despite aggressive multimodal treatment, high-risk neuroblastoma remains a clinical challenge with survival rates below 50%. Adding targeted drugs to first-line therapy regimens is a promising approach to improve survival in these patients. TACR1 activation by substance P has been reported to be mitogenic in cancer cell lines. Tachykinin receptor (TACR1) antagonists are approved for clinical use as an antiemetic remedy since 2003. Tachykinin receptor inhibition has recently been shown to effectively reduce growth of several tumor types. Here, we report that neuroblastoma cell lines express TACR1, and that targeting TACR1 activity significantly reduced cell viability and induced apoptosis in neuroblastoma cell lines. Gene expression profiling revealed that TACR1 inhibition repressed E2F2 and induced TP53 signaling. Treating mice harboring established neuroblastoma xenograft tumors with Aprepitant also significantly reduced tumor burden. Thus, we provide evidence that the targeted inhibition of tachykinin receptor signaling shows therapeutic efficacy in preclinical models for high-risk neuroblastoma.

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.

Mephebrindole, a synthetic indole analog coordinates the crosstalk between p38MAPK and eIF2α/ATF4/CHOP signalling pathways for induction of apoptosis in human breast carcinoma cells

The efficacy of cancer chemotherapeutics is limited by side effects resulting from narrow therapeutic windows between the anticancer activity of a drug and its cytotoxicity. Thus identification of small molecules that can selectively target cancer cells has gained major interest. Cancer cells under stress utilize the Unfolded protein response (UPR) as an effective cell adaptation mechanism. The purpose of the UPR is to balance the ER folding environment and calcium homeostasis under stress. If ER stress is prolonged, tumor cells undergo apoptosis. In the present study we demonstrated an 3,3'-(Arylmethylene)-bis-1H-indole (AMBI) derivative 3,3'-[(4-Methoxyphenyl) methylene]-bis-(5-bromo-1H-indole), named as Mephebrindole (MPB) as an effective anti-cancer agent in breast cancer cells. MPB disrupted calcium homeostasis in MCF7 cells which triggered ER stress development. Detailed evaluations revealed that mephebrindole by activating p38MAPK also regulated GRP78 and eIF2α/ATF4 downstream to promote apoptosis. Studies extended to in vivo allograft mice models revalidated its anti-carcinogenic property thus highlighting the role of MPB as an improved chemotherapeutic option.

Protective effect of berberine on acute cardiomyopathy associated with doxorubicin treatment

Doxorubicin (DOX) is a potent and broad-spectrum anthracycline chemotherapeutic agent, but dose-dependent cardiotoxic side effects limit its clinical application. This toxicity is closely associated with the generation of reactive oxygen species (ROS) radical during DOX metabolism. The present study investigated the effects of Berberine (Ber) on DOX-induced acute cardiac injury in a rat model and analysed its mechanism in cardiomyocytes in vitro. Serum creatine kinase (CK), creatine kinase isoenzyme (CK-MB) and malondialdehyde (MDA) levels were significantly increased in the DOX group compared with the control group. This increase was accompanied by cardiac histopathological injury and a decrease in cardiomyocyte superoxide dismutase (SOD) and catalase (CAT). CK, CK-MB and MDA levels decreased and SOD and CAT levels increased in the Ber-treated group compared to the DOX group. Ber ameliorated the DOX-induced increase in cytosolic calcium concentration ([Ca²⁺]_i), attenuated mitochondrial Ca²⁺ overload and restored the DOX-induced loss of mitochondrial membrane potential in vitro. These results demonstrated that Ber exhibited protective effects against DOX-induced heart tissue free radical injury, potentially via the inhibition of intracellular Ca²⁺ elevation and attenuation of mitochondrial dysfunction.

Targeting FOSB with a cationic antimicrobial peptide, TP4, for treatment of triple-negative breast cancer

Triple-negative breast cancer (TNBC) currently lacks a suitable therapeutic candidate and is thus difficult to treat. Here, we report that a cationic antimicrobial peptide (CAP), tilapia piscidin 4 (TP4), which was derived from Nile tilapia (Oreochromis niloticus), is selectively toxic to TNBC. TP4 acts by inducing an AP-1 protein called FOSB, the expression of which is negatively associated with the pathological grade of TNBC. We show that TP4 is bound to the mitochondria where it disrupts calcium homeostasis and activates FOSB. FOSB overexpression results in TNBC cell death, whereas inhibition of calcium signaling eliminates FOSB induction and blocks TP4-induced TNBC cell death. Both TP4 and anthracyclines strongly induced FOSB, particularly in TNBC, indicating that FOSB may be suitable as a biomarker of drug responses. This study thus provides a novel therapeutic approach toward TNBC through FOSB induction.

The Static Magnetic Field Remotely Boosts the Efficiency of Doxorubicin through Modulating ROS Behaviors

Exposure to magnetic field (MF) can affect cellular metabolism remotely. Cardio-toxic effects of Doxorubicin (DOXO) have limited clinical uses at high dose. MF due to its effect on reactive oxygen species (ROS) lifetime, may provide a suitable choice to boost the efficacy of this drug at low dose. Here, we investigated the potential effects of homogenous static magnetic field (SMF) on DOXO-induced toxicity and proliferation rate of cancer cells. The results indicated that SMF similar to DOXO decreased the cell viability as well as the proliferation rate of MCF-7 and HFF cells. Moreover, combination of 10 mT SMF and 0.1 µM DOXO decreased the viability and proliferation rate of cancer and normal cells in a synergetic manner. In spite of high a GSH level in cancer cell, SMF boosts the generation and lifetime of ROS at low dose of DOXO, and overcame to GSH mediated drug resistance. The results also confirmed that SMF exposure decreased 50% iron content of cells, which is attributed to iron homeostasis. In conclusion, these findings suggest that SMF can decrease required dose of chemotherapy drugs such as DOXO and thereby decrease their side effect.

Experimental evidence of good efficacy and reduced toxicity with peptide-doxorubicin to treat gastric cancer

BACKGROUND

To compare the efficacy and toxicity of peptide-doxorubicin (PDOX) and doxorubicin (DOX) on nude mice models of human gastric cancer.

RESULTS

Both PDOX and DOX could significantly inhibit tumor growth compared with Control (P < 0.05) in both subcutaneous and orthotopic models. Animal survival was much better in PDOX group than DOX group. In peripheral blood test, PDOX group had significantly higher levels of platelets than the Control (P < 0.05), and lymphocyte lower than Control (P < 0.05). There were no significant differences on liver, kidney and cardiac function parameters among three groups (P > 0.05). Immunohistochemistry showed that treatment groups had much higher Tunel than Control (P < 0.05), and PDOX had significantly lower Ki-67 than doxorubicin and Control group (P < 0.01). Western blotting showed that PDOX caused much higher expressions of P53, P21, Aparf-1, pro- and cleaved-caspase 3, compared with DOX.

CONCLUSION

Compared with DOX, PDOX has increased effects but much decreased toxicity in treating animal model of gastric cancer.

MATERIALS AND METHODS

Animals in subcutaneous model were randomized into Control, doxorubicin, PDOX-L, PDOX-M, and PDOX-H groups. Animals in surgical orthotopic implantation model were randomized into Control, doxorubicin and, peptide-doxorubicin groups. The animals were treated, monitored and examined following a set protocol.

Site-specific anchoring aptamer C2NP on DNA origami nanostructures for cancer treatment

Aptamer anchored DNA nanostructures not only can enhance the anticancer activity of DOX, but also exhibit synergic biological effect with chemotherapy on cancer therapy.

Synthesis of enzyme-responsive phosphoramidate dendrimers for cancer drug delivery

Enzyme-responsive phosphoramidate dendrimers were successfully synthesized and their surfaces were modified with zwitterionic groups for cancer drug delivery.

Chemical characterization, antioxidant, genotoxic and in vitro cytotoxic activity assessment of Juniperus communis var. saxatilis

Chemical composition and antioxidative, genotoxic and cytotoxic potential of essential oil (EO) and post-distillation waste (PDW) of Serbian Juniperus communis L. var. saxatilis Pall. was studied in human lung carcinoma (A549) and normal lung fibroblast (MRC-5) cells. GC-MS analysis identified 93.95% of total EO content and determined α-pinen as a dominant component (23.61%). LC-MS/MS analysis of PDW pointed at rutin (12.2 mg g^-1) and quinic acid (11.1 mg g^-1) as the most abundant. Antioxidativity of PDW was strong in DPPH (IC₅₀ was 5.27 μg mL^-1), and moderate in TBA and FRAP assays. Both substances were more cytotoxic to A549 than to MRC-5 cells. Obtained IC₅₀ values were 69.4 μg mL^-1 and 120 μg mL^-1 for EO, and 1.27 mg mL^-1 and 2.86 mg mL^-1 for PDW, respectively. PDW was genotoxic (0.3 mg mL^-1 and 1 mg mL^-1 in A549 and MRC-5 cells, respectively) and induced apoptosis and arrested cell cycle in G2/M phase in A549 cells (0.3 mg mL^-1). In mixtures with doxorubicin cytotoxicity of EO and PDW increased, and combination index values (0.12-0.18) revealed clear synergistic effect, stronger in cancer cells. This indicates that J. communis var. saxatilis could decrease the chemotherapeutic doses of doxorubicin, potentially reducing its side effects.

Pharmacological stimulation of p53 with low-dose doxorubicin ameliorates diet-induced nonalcoholic steatosis and steatohepatitis

Objective

Recent reports have implicated the p53 tumor suppressor in the regulation of lipid metabolism. We hypothesized that the pharmacological activation of p53 with low-dose doxorubicin, which is widely used to treat several types of cancer, may have beneficial effects on nonalcoholic fatty liver disease (NAFLD) and nonalcoholic steatohepatitis (NASH).

Methods

We used long-term pharmacological activation of p53 by i.p. or oral administration of low-dose doxorubicin in different animal models of NAFLD (high fat diet containing 45% and 60% kcal fat) and NASH (methionine- and choline-deficient diet and choline deficiency combined with high fat diet). We also administered doxorubicin in mice lacking p53 in the liver and in two human hepatic cells lines (HepG2 and THLE2).

Results

The attenuation of liver damage was accompanied by the stimulation of fatty acid oxidation and decrease of lipogenesis, inflammation, and ER stress. The effects of doxorubicin were abrogated in mice with liver-specific ablation of p53. Finally, the effects of doxorubicin on lipid metabolism found in animal models were also present in two human hepatic cells lines, in which the drug stimulated fatty acid oxidation and inhibited de novo lipogenesis at doses that did not cause changes in apoptosis or cell viability.

Conclusion

These data provide new evidence for targeting p53 as a strategy to treat liver disease.

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Intraperitoneal and oral low-dose doxorubicin ameliorates NAFLD and NASH in animal models.

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Doxorubicin requires p53 for its hepatic actions.

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Doxorubin decreases lipid content in human hepatocytes without affecting cell viability and apoptosis.

A role for caspase-2 in sphingosine kinase 1 proteolysis in response to doxorubicin in breast cancer cells - implications for the CHK1-suppressed pathway

Sphingosine kinase 1 (SK1) is a lipid kinase whose activity produces sphingosine 1‐phosphate, a prosurvival lipid associated with proliferation, angiogenesis, and invasion. SK1 overexpression has been observed in numerous cancers. Recent studies have demonstrated that SK1 proteolysis occurs downstream of the tumor suppressor p53 in response to several DNA‐damaging agents. Moreover, loss of SK1 in p53‐knockout mice resulted in complete protection from thymic lymphoma, providing evidence that regulation of SK1 constitutes a major tumor suppressor function of p53. Given this profound phenotype, this study aimed to investigate the mechanism by which wild‐type p53 regulates proteolysis of SK1 in response to the DNA‐damaging agent doxorubicin in breast cancer cells. We find that p53‐mediated activation of caspase‐2 was required for SK1 proteolysis and that caspase‐2 activity significantly alters the levels of endogenous sphingolipids. As p53 is mutated in 50% of all cancers, we extended our studies to investigate whether SK1 is deregulated in the context of triple‐negative breast cancer cells (TNBC) harboring a mutation in p53. Indeed, caspase‐2 was not activated in these cells and SK1 was not degraded. Moreover, caspase‐2 activation was recently shown to be downstream of the CHK1‐suppressed pathway in p53‐mutant cells, whereby inhibition of the cell cycle kinase CHK1 leads to caspase‐2 activation and apoptosis. Indeed, knockdown and inhibition of CHK1 led to the loss of SK1 in p53‐mutant TNBC cells, providing evidence that SK1 may be the first identified effector of the CHK1‐suppressed pathway.

Novel Doxorubicin Derivatives: Synthesis and Cytotoxicity Study in 2D and 3D in Vitro Models

Purpose: Multidrug resistance (MDR) of tumors to chemotherapeutics often leads to failure of cancer treatment. The aim of the study was to prepare novel MDR-overcoming chemotherapeutics based on doxorubicin (DOX) derivatives and to evaluate their efficacy in 2D and 3D in vitro models. Methods: To overcome MDR, we synthesized five DOX derivatives, and then obtained non-covalent complexes with human serum albumin (HSA). Drug efficacy was evaluated for two tumor cell lines, namely human breast adenocarcinoma MCF-7 cells and DOX resistant MCF-7/ADR cells. Additionally, MCF-7 cells were entrapped in alginate-oligochitosan microcapsules, and generated tumor spheroids were used as a 3D in vitro model to study cytotoxicity of the DOX derivatives. Results: Due to 3D structure, the tumor spheroids were more resistant to chemotherapy compared to monolayer culture. DOX covalently attached to palmitic acid through hydrazone linkage (DOX-N2H-Palm conjugate) was found to be the most promising derivative. Its accumulation levels within MCF-7/ADR cells was 4- and 10-fold higher than those of native DOX when the conjugate was added to cultivation medium without serum and to medium supplemented with 10% fetal bovine serum, respectively. Non-covalent complex of the conjugate with HSA was found to reduce the IC50 value from 32.9 µM (for free DOX-N2H-Palm) to 16.8 µM (for HSA-DOX-N2H-Palm) after 72 h incubation with MCF-7/ADR cells. Conclusion: Palm-N2H-DOX conjugate was found to be the most promising DOX derivative in this research. The formation of non-covalent complex of Palm-N2H-DOX conjugate with HSA allowed improving its anti-proliferative activity against both MCF-7 and MCF-7/ADR cells.

Accumulation of tissue factor in endothelial cells induces cell apoptosis, mediated through p38 and p53 activation

We previously reported that high levels of tissue factor (TF) can induce cellular apoptosis in endothelial cells. In this study, TF-mediated mechanisms of induction of apoptosis were explored. Endothelial cells were transfected to express wild-type TF. Additionally, cells were transfected to express Asp253-substituted, or Ala253-substitued TF to enhance or prevent TF release, respectively. Alternatively, cells were pre-incubated with TF-rich and TF-poor microvesicles. Cell proliferation, apoptosis and the expression of cyclin D1, p53, bax and p21 were measured following activation of cells with PAR2-agonist peptide. Greatest levels of cell proliferation and cyclin D1 expression were observed in cells expressing wild-type or Asp253-substituted TF. In contrast, increased cellular apoptosis was observed in cells expressing Ala253-substituted TF, or cells pre-incubated with TF-rich microvesicles. The level of p53 protein, p53-phosphorylation at ser33, p53 nuclear localisation and transcriptional activity, but not p53 mRNA, were increased in cells expressing wild-type and Ala253-substituted TF, or in cells pre-incubated with TF-rich microvesicles. However, the expression of bax and p21 mRNA, and Bax protein were only increased in cells pre-incubated with TF-rich microvesicle and in cells expressing Ala253-substituted TF. Inhibition of the transcriptional activity of p53 using pifithrin-α suppressed the expression of Bax. Finally, siRNA- mediated suppression of p38α, or inhibition using SB202190 significantly reduced the p53 protein levels, p53 nuclear localisation and transcriptional activity, suppressed Bax expression and prevented cellular apoptosis. In conclusion, accumulation of TF within endothelial cells, or sequestered from the surrounding can induce cellular apoptosis through mechanisms mediated by p38, and involves the stabilisation of p53.

Exploiting bilosomes for delivering bioactive polysaccharide isolated from Enteromorpha intestinalis for hacking hepatocellular carcinoma

Bile salts containing vesicles (bilosomes) represent a portentous vesicular carrier that showed prosperous results in delivering active moieties in the gastrointestinal tract (GIT). In this study, bilosomes were exploited to deliver sulfated polysaccharide-protein complexes of Enteromorpha intestinalis (EHEM) and enhance its activity against hepatocellular carcinoma as well as resist harsh GIT conditions. Bilosomes were prepared using the sodium salt of three different bile acids (cholic, deoxycholic, taurodeoxycholic) and two different nonionic surfactants (Span 40 and 65). The effects of experimental variables were thoroughly studied to obtain an optimum formulation loading EHEM. The selected formulation (EH-Bilo-2) prepared with sodium cholate and Span 65 displayed nano-sized (181.1 ± 16.80 nm) spherical vesicles with reasonable entrapment efficiency (71.60 ± 0.25%) and controlled release properties; and thus was investigated as anti-hepatocarcinogenic candidate for in vivo studies. Treatment of hepatocellular carcinoma (HCC) bearing rats with EH-Bilo-2 experienced significant decrease in serum α-fetoprotein, endoglin, lipocalin-2, and heat shock protein 70 levels vs. the untreated counterparts. Furthermore, the photomicrographs of their liver tissue sections showed focal area of degenerated pleomorphic hepatocytes with fine fibrosis originating from the portal area. Thus, the optimized bilosomal formulation is a promising delegate for tackling hepatocellular carcinoma owing to its powerful anti-cancer and anti-angiogenic activity.

Inhibition of Thioredoxin Reductase by Targeted Selenopolymeric Nanocarriers Synergizes the Therapeutic Efficacy of Doxorubicin in MCF7 Human Breast Cancer Cells

Increasing evidence suggests selenium nanoparticles (Se NPs) as potential cancer therapeutic agents and emerging drug delivery carriers, yet, the molecular mechanism of their anticancer activity still remains unclear. Recent studies indicate thioredoxin reductase (TrxR), a selenoenzyme, as a promising target for anticancer therapy. The present study explored the TrxR inhibition efficacy of Se NPs as a plausible factor impeding tumor growth. Hyaluronic acid (HA)-functionalized selenopolymeric nanocarriers (Se@CMHA NPs) were designed wielding chemotherapeutic potential for target specific Doxorubicin (DOX) delivery. Se@CMHA nanocarriers are thoroughly characterized asserting their chemical and physical integrity and possess prolonged stability. DOX-loaded selenopolymeric nanocarriers (Se@CMHA-DOX NPs) exhibited enhanced cytotoxic potential toward human cancer cells compared to free DOX in an equivalent concentration eliciting its selectivity. In first-of-its-kind findings, selenium as Se NPs in these polymeric carriers progressively inhibit TrxR activity, further augmenting the anticancer efficacy of DOX through a synergistic interplay between DOX and Se NPs. Detailed molecular studies on MCF7 cells also established that upon exposure to Se@CMHA-DOX NPs, MCF7 cells endure G2/M cell cycle arrest and p53-mediated caspase-independent apoptosis. To gauge the relevance of the developed nanosystem in in vivo settings, three-dimensional tumor sphere model mimicking the overall tumor environment was also performed, and the results clearly depict the effectiveness of our nanocarriers in reducing tumor activity. These findings are reminiscent of the fact that our Se@CMHA-DOX NPs could be a viable modality for effective cancer chemotherapy.

Dual targeting of the cancer antioxidant network with 1,4-naphthoquinone fused Gold(i) N-heterocyclic carbene complexes

To achieve a systems-based approach to targeting the antioxidant pathway, 1,4-naphthoquinone annulated N-heterocyclic carbene (NHC) [bis(1,3-dimesityl-4,5-naphthoquino-imidazol-2-ylidene)-gold(i)] [silver(i) dichloride] (1), [bis(1,3-dimesityl-4,5-naphthoquino-imidazol-2-ylidene)-gold(i)] chloride (2), and 1,3-dimesityl-4,5-naphthoquino-imidazol-2-ylidene)-gold(i) chloride (3)) were designed, synthesized, and tested for biological activity in a series of human cancer cell lines. The solution phase of complexes 1-3 were assigned using several spectroscopy techniques, including NMR spectroscopic analysis. Complexes 1 and 3 were further characterized by single crystal X-ray diffraction analysis. Electrochemical and spectroelectrochemical studies revealed that quinone reductions are reversible and that the electrochemically generated semiquinone and quinone dianions are stable under these conditions. Complex 1, containing two NHC-quinone moieties (to accentuate exogenous ROS via redox cycling) centered around a Au(i) center (to inactivate thioredoxin reductase (TrxR) irreversibly), was found to inhibit cancer cell proliferation to a much greater extent than the individual components (i.e., Au(i)-NHC alone or naphthoquinone alone). Treatment of A549 lung cancer cells with 1 produced a 27-fold increase in exogenous reactive oxygen species (ROS) which was found to localize to the mitochondria. The inhibition of TrxR, an essential mediator of ROS homeostasis, was achieved in the same cell line at low administrated concentrations of 1. TrxR inhibition by 1 was similar to that of auranofin, a gold(i) containing complex known to inhibit TrxR irreversibly. Complex 1 was found to induce cell death via an apoptotic mechanism as confirmed by annexin-V staining. Complex 1 was demonstrated to be efficacious in zebrafish bearing A549 xenografts. These results provide support for the suggestion that a dual targeting approach that involves reducing ROS tolerance while concurrently increasing ROS production can perturb antioxidant homeostasis, enhance cancer cell death in vitro, and reduce tumor burden in vivo, as inferred from preliminary zebra fish model studies.

Sensitive Electrochemical Detection of Nitric Oxide Release from Cardiac and Cancer Cells via a Hierarchical Nanoporous Gold Microelectrode

The importance of nitric oxide (NO) in many biological processes has garnered increasing research interest in the design and development of efficient technologies for the sensitive detection of NO. Here we report on a novel gold microelectrode with a unique three-dimensional (3D) hierarchical nanoporous structure for the electrochemical sensing of NO, which was fabricated via a facile electrochemical alloying/dealloying method. Following the treatment, the electrochemically active surface area (ECSA) of the gold microelectrode was significantly increased by 22.9 times. The hierarchical nanoporous gold (HNG) microelectrode exhibited excellent performance for the detection of NO with high stability. On the basis of differential pulse voltammetry (DPV) and amperometric techniques, the obtained sensitivities were 21.8 and 14.4 μA μM^-1 cm^-2, with detection limits of 18.1 ± 1.22 and 1.38 ± 0.139 nM, respectively. The optimized HNG microelectrode was further utilized to monitor the release of NO from different cells, realizing a significant differential amount of NO generated from the normal and stressed rat cardiac cells as well as from the untreated and treated breast cancer cells. The HNG microelectrode developed in the present study may provide an effective platform in monitoring NO in biological processes and would have a great potential in the medical diagnostics.

Doxorubicin Hydrochloride Loaded Zymosan-Polyethylenimine Biopolymeric Nanoparticles for Dual 'Chemoimmunotherapeutic' Intervention in Breast Cancer

OBJECTIVE

To utilize nanoparticles produced by condensation of zymosan (an immunotherapeutic polysaccharide) with pegylated polyethylenimine (PEG-PEI) for dual intervention in breast cancer by modulating tumor microenvironment and direct chemotherapy.

METHOD

Positively charged PEG-PEI and negatively charged sulphated zymosan were utilized for electrostatic complexation of chemoimmunotherapeutic nanoparticles (ChiNPs). ChiNPs were loaded with doxorubicin hydrochloride (DOX) for improved delivery at tumor site and were tested for in-vivo tolerability. Biodistribution studies were conducted to showcase their effective accumulation in tumor hypoxic regions where tumor associated macrophages (TAMs) are preferentially recruited.

RESULTS

ChiNPs modulated TAMs differentiation resulting in decrement of CD206 positive population. This immunotherapeutic action was furnished by enhanced expression of Th1 specific cytokines. ChiNPs also facilitated an anti-angiogenetic effect which further reduces the possibility of tumor progression and metastasis.

Metformin augments doxorubicin cytotoxicity in mammary carcinoma through activation of adenosine monophosphate protein kinase pathway

Since the incidence of breast cancer increases dramatically all over the world, the search for effective treatment is an urgent need. Metformin has demonstrated anti-tumorigenic effect both in vivo and in vitro in different cancer types. This work was designed to examine on molecular level the mode of action of metformin in mice bearing solid Ehrlich carcinoma and to evaluate the use of metformin in conjunction with doxorubicin as a combined therapy against solid Ehrlich carcinoma. Ehrlich ascites carcinoma cells were inoculated in 60 female mice as a model of breast cancer. The mice were divided into four equal groups: Control tumor, metformin, doxorubicin, and co-treatment. Metformin (15 mg/kg) and doxorubicin (4 mg/kg) were given intraperitoneally (i.p.) for four cycles every 5 days starting on day 12 of inoculation. The anti-tumorigenic effect of metformin was mediated by enhancement of adenosine monophosphate protein kinase activity and elevation of P53 protein as well as the suppression of nuclear factor-kappa B, DNA contents, and cyclin D1 gene expression. Metformin and doxorubicin mono-treatments exhibited opposing action regarding cyclin D1 gene expression, phosphorylated adenosine monophosphate protein kinase, and nuclear factor-kappa B levels. Co-treatment markedly decreased tumor volume, increased survival rate, and improved other parameters compared to doxorubicin group. In parallel, the histopathological findings demonstrated enhanced apoptosis and absence of necrosis in tumor tissue of co-treatment group. Metformin proved chemotherapeutic effect which could be mediated by the activation of adenosine monophosphate protein kinase and related pathways. Combining metformin and doxorubicin, which exhibited different mechanisms of action, produced greater efficacy as anticancer therapeutic regimen.

ROS signalling in the biology of cancer

Increased reactive oxygen species (ROS) production has been detected in various cancers and has been shown to have several roles, for example, they can activate pro-tumourigenic signalling, enhance cell survival and proliferation, and drive DNA damage and genetic instability. Counterintuitively ROS can also promote anti-tumourigenic signalling, initiating oxidative stress-induced tumour cell death. Tumour cells express elevated levels of antioxidant proteins to detoxify elevated ROS levels, establish a redox balance, while maintaining pro-tumourigenic signalling and resistance to apoptosis. Tumour cells have an altered redox balance to that of their normal counterparts and this identifies ROS manipulation as a potential target for cancer therapies. This review discusses the generation and sources of ROS within tumour cells, the regulation of ROS by antioxidant defence systems, as well as the effect of elevated ROS production on their signalling targets in cancer. It also provides an insight into how pro- and anti-tumourigenic ROS signalling pathways could be manipulated in the treatment of cancer.

Optical imaging and anticancer chemotherapy through carbon dot created hollow mesoporous silica nanoparticles

Multifunctional nanocarrier-based theranostics is currently considered to solve some key unmet challenges in cancer treatment. Here we report a nanocarrier platform, named carbon dot (CD) created mesoporous hollow organosilica (C-hMOS) nanoparticles, to deliver anticancer drug and to enable optical imaging. The hollow structure was formed by the removal of a nanorod core template, and at the same time, the fluorescent signal was endowed from the heat-treated organosilica network. Thanks to the hollow and mesoporous structure, the C-hMOS effectively loaded doxorubicin (DOX) for cancer chemotherapy. The DOX was released from C-hMOS highly sustainably (over 12days) and pH-dependently (pH 5.0 >pH 7.4). The DOX-loading C-hMOS internalized cancer cells efficiently (>90%), and induced cellular apoptosis including the expression of caspase-3. The treatment of C-hMOS to cancer cells enabled multi-color visualization in vitro, suggesting the possibility of cell tracing. Moreover, when injected intratumorally in mice, the C-hMOS exhibited strong optical signals in vivo along with a high optical stability (over a week). The injected C-hMOS were distributed only a fraction in liver but not in heart, lung, spleen or kidney and displayed good biocompatibility. The DOX-delivering C-hMOS significantly suppressed the in vivo tumor growth associated with apoptotic functions. Taken together, the developed C-hMOS nanoparticles can be a promising nanoplatform for drug delivery and in vivo imaging in cancer treatment.

STATEMENT OF SIGNIFICANCE

Multifunctional nanoparticles that combine chemotherapeutic ability with imaging modality comprise promising platform for cancer theranostics. Here we developed a novel theranostic nanoparticle, i.e., carbon-dot created mesoporous hollow silica nanoparticle, to offer unique merit for this purpose. The in vitro and in vivo findings to support this include: i) carbon dots with 1-2nm size in situ generated discretely and uniformly within silica network, ii) hollow and mesoporous structure effective for loading of DOX at high content, iii) release behavior of DOX in a sustainable and pH-dependent manner, iv) chemotherapeutic efficacy in killing cancer cells and suppressing tumor growth through DOX delivery, and v) carbon dot induced multi-color fluorescence imaging within cells and tumor tissues. These collective multifaceted properties may facilitate the novel carbon dot nanocarriers to be a potential candidate for delivering anticancer drug and non-invasive imaging in cancer treatment.

Nuclear Localizing Peptide-Conjugated, Redox-Sensitive Polymersomes for Delivering Curcumin and Doxorubicin to Pancreatic Cancer Microtumors

Improving the therapeutic index of anticancer agents is an enormous challenge. Targeting decreases the side effects of the therapeutic agents by delivering the drugs to the intended destination. Nanocarriers containing the nuclear localizing peptide sequences (NLS) translocate to the cell nuclei. However, the nuclear localization peptides are nonselective and cannot distinguish the malignant cells from the healthy counterparts. In this study, we designed a "masked" NLS peptide which is activated only in the presence of overexpressed matrix metalloproteinase-7 (MMP-7) enzyme in the pancreatic cancer microenvironment. This peptide is conjugated to the surface of redox responsive polymersomes to deliver doxorubicin and curcumin to the pancreatic cancer cell nucleus. We have tested the formulation in both two- and three-dimensional cultures of pancreatic cancer and normal cells. Our studies revealed that the drug-encapsulated polymeric vesicles are significantly more toxic toward the cancer cells (shrinking the spheroids up to 49%) compared to the normal cells (shrinking the spheroids up to 24%). This study can lead to the development of other organelle targeted drug delivery systems for various human malignancies.

HDAC Inhibitor Conjugated Polymeric Prodrug Micelles for Doxorubicin Delivery

Amphiphilic diblock copolymers bearing histone deacetylase inhibitors (HDACi) (4-phenyl butyric acid and valproic acid) were synthesized by the ring-opening polymerization of γ-4-phenylbutyrate-ε-caprolactone (PBACL), γ-valproate-ε-caprolactone (VPACL), and ε-caprolactone (CL) from a poly(ethylene glycol) macroinitiator (PEG). These amphiphilic diblock copolymers self-assembled into stable pro-drug micelles and demonstrated excellent biocompatibility. High loading of doxorubicin (DOX) up to 5.1 wt% was achieved. Optimized micelles enabled sustained drug release in a concentration-dependent manner over time to expand the therapeutic window of cytotoxic small molecule drugs.

Englerin A induces an acute inflammatory response and reveals lipid metabolism and ER stress as targetable vulnerabilities in renal cell carcinoma

Renal cell carcinoma (RCC) is among the top ten most common forms of cancer and is the most common malignancy of the kidney. Clear cell renal carcinoma (cc-RCC), the most common type of RCC, is one of the most refractory cancers with an incidence that is on the rise. Screening of plant extracts in search of new anti-cancer agents resulted in the discovery of englerin A, a guaiane sesquiterpene with potent cytotoxicity against renal cancer cells and a small subset of other cancer cells. Though a few cellular targets have been identified for englerin A, it is still not clear what mechanisms account for the cytotoxicity of englerin A in RCC, which occurs at concentrations well below those used to engage the targets previously identified. Unlike any prior study, the current study used a systems biology approach to explore the mechanism(s) of action of englerin A. Metabolomics analyses indicated that englerin A profoundly altered lipid metabolism by 24 h in cc-RCC cell lines and generated significant levels of ceramides that were highly toxic to these cells. Microarray analyses determined that englerin A induced ER stress signaling and an acute inflammatory response, which was confirmed by quantitative PCR and Western Blot analyses. Additionally, fluorescence confocal microscopy revealed that englerin A at 25 nM disrupted the morphology of the ER confirming the deleterious effect of englerin A on the ER. Collectively, our findings suggest that cc-RCC is highly sensitive to disruptions in lipid metabolism and ER stress and that these vulnerabilities can be targeted for the treatment of cc-RCC and possibly other lipid storing cancers. Furthermore, our results suggest that ceramides may be a mediator of some of the actions of englerin A. Lastly, the acute inflammatory response induced by englerin A may mediate anti-tumor immunity.

Depletion of enteric bacteria diminishes leukocyte infiltration following doxorubicin-induced small intestinal damage in mice

Background & aims

While enteric bacteria have been shown to play a critical role in other forms of intestinal damage, their role in mediating the response to the chemotherapeutic drug Doxorubicin (Doxo) is unclear. In this study, we used a mouse model of intestinal bacterial depletion to evaluate the role enteric bacteria play in mediating Doxo-induced small intestinal damage and, more specifically, in mediating chemokine expression and leukocyte infiltration following Doxo treatment. An understanding of this pathway may allow for development of intervention strategies to reduce chemotherapy-induced small intestinal damage.

Methods

Mice were treated with (Abx) or without (NoAbx) oral antibiotics in drinking water for four weeks and then with Doxo. Jejunal tissues were collected at various time points following Doxo treatment and stained and analyzed for apoptosis, crypt damage and restitution, and macrophage and neutrophil number. In addition, RNA expression of inflammatory markers (TNFα, IL1-β, IL-10) and cytokines (CCL2, CC7, KC) was assessed by qRT-PCR.

Results

In NoAbx mice Doxo-induced damage was associated with rapid induction of apoptosis in jejunal crypt epithelium and an increase weight loss and crypt loss. In addition, we observed an increase in immune-modulating chemokines CCL2, CCL7 and KC and infiltration of macrophages and neutrophils. In contrast, while still positive for induction of apoptosis following Doxo treatment, Abx mice showed neither the overall weight loss nor crypt loss seen in NoAbx mice nor the increased chemokine expression and leukocyte infiltration.

Conclusion

Enteric bacteria play a critical role in Doxo-induced small intestinal damage and are associated with an increase in immune-modulating chemokines and cells. Manipulation of enteric bacteria or the damage pathway may allow for prevention or treatment of chemotherapy-induced small intestinal damage.

Stimulative nanogels with enhanced thermosensitivity for therapeutic delivery via β-cyclodextrin-induced formation of inclusion complexes

To explore the potential biomedical application of thermoresponsive nanosystems, it is important to enhance their thermosensitivity to improve the controllability in delivery of therapeutic agents. The present work develops multifunctional nanogels with enhanced thermosensitivity through copolymerization of N-isopropylacrylamide (NIPAM) and acrylic acid (AA) in the presence of β-cyclodextrin (β-CD), using N,N'-bis(acryloyl)cystamine (BAC) as a biodegradable crosslinker. The resulting nanogels display significantly improved sensitivity in deswelling (swelling) behavior upon temperature increase (decrease) around body temperature. The nanogels can effectively encapsulate doxorubicin (DOX), which can be released in an accelerated way under microenvironments that mimic intracellular reductive conditions and acidic tumor tissues. Release can also be remotely manipulated by increasing temperature. In vitro study indicates that the nanogels are quickly taken up by KB cells (a human epithelial carcinoma cell line), exerting improved anticancer cytotoxicity, showing their potential for delivery of therapeutic agents beyond anticancer drugs.

A herbal formula, SYKT, reverses doxorubicin‑induced myelosuppression and cardiotoxicity by inhibiting ROS‑mediated apoptosis

Doxorubicin (DOX) is an antineoplastic drug widely used for the treatment of various types of cancer; however, it can induce severe side effects, such as myelosuppression and cardiotoxicity. Sanyang Xuedai (SYKT) is a natural medicine originating from an ancient prescription of the Dai nationality in Southwest China. With eight Chinese herbal medicines, including sanguis draconis, radix et rhizoma notoginseng, radix et rhizoma glycyrrhizae and radix angelicae sinensis as the primary ingredients, SYKT has been reported to possess numerous biological functions. The present study investigated whether SYKT can confer protection against DOX-induced myelosuppression and cardiotoxicity, and explored the potential mechanism involved. Mice were treated with DOX, SYKT or a combination of the two; hematopoietic functions were assessed by measuring the number of peripheral blood cells, cluster of differentiation CD34+/CD44+ bone marrow cells and apoptotic cells. Myocardial enzymes, including aspartate aminotransferase, lactate dehydrogenase, creatine kinase (CK) and its isoform CK-MB, were assessed using a biochemical analyzer. The apoptotic rate of cardiomyocytes was assessed using flow cytometry. Histopathological analysis was conducted using hematoxylin-eosin staining. Intracellular reactive oxygen species (ROS) production was evaluated using a dichlorofluorescein intensity assay. The mice treated with DOX exhibited a reduced survival rate, reduced peripheral blood and CD34+/CD44+ cell counts, elevated myocardial enzymes and apoptotic indices in bone marrow cells and cardiomyocytes, all of which were effectively prevented by SYKT co-administration. Furthermore, bone marrow cells and myocytes from mice treated with DOX demonstrated increased dichlorofluorescein intensity, which was attenuated by SYKT. Notably, SYKT did not interfere with the effects of DOX on tumor volume or the induction of tumor cell apoptosis in tumor-bearing mice. The present study indicated that SYKT may counteract DOX-induced myelosuppression and cardiotoxicity through inhibiting ROS-mediated apoptosis. These findings suggested that SYKT may have potential as a means to counteract the potentially fatal hematopoietic and cardiac complications associated with DOX treatment.

Foxo3a inhibits mitochondrial fission and protects against doxorubicin-induced cardiotoxicity by suppressing MIEF2

Doxorubicin (DOX) as a chemotherapeutic drug is widely used to treat a variety of human tumors. However, a major factor limiting its clinical use is its cardiotoxicity. The molecular components and detailed mechanisms regulating DOX-induced cardiotoxicity remain largely unidentified. Here we report that Foxo3a is downregulated in the cardiomyocyte and mouse heart in response to DOX treatment. Foxo3a attenuates DOX-induced mitochondrial fission and apoptosis in cardiomyocytes. Cardiac specific Foxo3a transgenic mice show reduced mitochondrial fission, apoptosis and cardiotoxicity upon DOX administration. Furthermore, Foxo3a directly targets mitochondrial dynamics protein of 49kDa (MIEF2) and suppresses its expression at transcriptional level. Knockdown of MIEF2 reduces DOX-induced mitochondrial fission and apoptosis in cardiomyocytes and in vivo. Also, knockdown of MIEF2 protects heart from DOX-induced cardiotoxicity. Our study identifies a novel pathway composed of Foxo3a and MIEF2 that mediates DOX cardiotoxicity. This discovery provides a promising therapeutic strategy for the treatment of cancer therapy and cardioprotection.

Promotion of HepG2 cell apoptosis by flower of Allium atroviolaceum and the mechanism of action

Background

Liver cancer is a high incidence and fatal disease, the fifth most frequent cancer worldwide that is usually diagnosed at an advanced stage. The number of deaths from liver cancer has not declined even following various therapies. Plant secondary metabolites and their semi-synthetic derivatives play a principal role in anti-cancer drug therapy, since they are effective in the treatment of specific characteristics while also reducing side effects. Allium atroviolaceum, a plant of the genus Allium has been used in folk medicine to protect against several diseases. However, cytotoxicity and the anti-proliferative effect of Allium atroviolaceum remain unclear. This work aims to investigate the anticancer properties of Allium atroviolaceum and the mechanism of action.

Methods

To evaluate the in vitro cytotoxicity of flower of Allium atroviolaceum, methanol extract at a dose range from 100 to 3.12 μg/ml was assessed against the HepG2 hepatocarcinoma cell line, and also on normal 3T3 cells, by monitoring proliferation using the MTT assay method. A microscopy study was undertaken to observe morphological changes of HepG2 cells after treatment and cell cycle arrest and apoptosis were studied using flow cytometry. The apoptosis mechanism of action was assessed by the level of caspase-3 activity and expression of apoptosis related genes, Bcl-2, Cdk1 and p53. The combination effect of the methanolic extract with doxorubicin was also investigated by determination of a combination index.

Results

The results demonstrated growth inhibition of cells in both dose- and time-dependent manners, while no cytotoxic effect on normal cell 3T3 was found. The results revealed the occurrence of apoptosis, illustrated by sub-G0 cell cycle arrest, the change in morphological feature and annexin-V and propidium iodide staining, which is correlated with Bcl-2 downregulation and caspase-3 activity, but p53-independent. In addition, a combination of Allium atroviolaceum and doxorubicin led to a significant synergistic effect.

Conclusion

These findings suggest that Allium atroviolaceum flower extract has potential as a potent cytotoxic agent against HepG2 cell lines, as it has commendable anti-proliferative activities against human hepatocarcinoma and it can be considered as an effective adjuvant therapeutic agent after the clinical trials.

Protective effect of Co-enzyme Q10 On doxorubicin-induced cardiomyopathy of rat hearts

Q10 is a powerful antioxidant often used in medical nutritional supplements for cancer treatment. This study determined whether Q10 could effectively prevent cardio-toxicity caused by doxorubicin treatment. Four week old SD rats were segregated into groups namely control, doxorubicin group (challenged with doxorubicin), Dox + Q10 group (with doxorubicin challenge and oral Q10 treatment), and Q10 group (with oral Q10 treatment). Doxorubicin groups received IP doxorubicin (2.5 mg/kg) every 3 days and Q10 groups received Q10 (10 mg/kg) every day. Three weeks of doxorubicin challenge caused significant reduction in heart weight, disarray in cardiomyocyte arrangement, elevation of collagen accumulation, enhancement of fibrosis and cell death associated proteins, and inhibition of survival proteins. However, Q10 effectively protected cardiomyocytes and ameliorated fibrosis and cell death induced by doxorubicin. Q10 is, therefore, evidently a potential drug to prevent heart damage caused by doxorubicin. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 679-689, 2017.

Statins in anthracycline-induced cardiotoxicity: Rac and Rho, and the heartbreakers

Cancer patients receiving anthracycline-based chemotherapy are at risk to develop life-threatening chronic cardiotoxicity with the pathophysiological mechanism of action not fully understood. Besides the most common hypothesis that anthracycline-induced congestive heart failure (CHF) is mainly caused by generation of reactive oxygen species, recent data point to a critical role of topoisomerase II beta (TOP2B), which is a primary target of anthracycline poisoning, in the pathophysiology of CHF. As the use of the only clinically approved cardioprotectant dexrazoxane has been limited by the FDA in 2011, there is an urgent need for alternative cardioprotective measures. Statins are anti-inflammatory and anti-oxidative drugs that are clinically well established for the prevention of cardiovascular diseases. They exhibit pleiotropic beneficial properties beyond cholesterol-lowering effects that most likely rest on the indirect inhibition of small Ras homologous (Rho) GTPases. The Rho GTPase Rac1 has been shown to be a major factor in the regulation of the pro-oxidative NADPH oxidase as well as in the regulation of type II topoisomerase. Both are discussed to play an important role in the pathophysiology of anthracycline-induced CHF. Therefore, off-label use of statins or novel Rac1 inhibitors might represent a promising pharmacological approach to gain control over chronic cardiotoxicity by interfering with key mechanisms of anthracycline-induced cardiomyocyte cell death.

Polyethylenimine-functionalized carbon nanotubes tagged with AS1411 aptamer for combination gene and drug delivery into human gastric cancer cells

In this project, synergistic cancer cell death was achieved by a targeted delivery system comprising Bcl-xL-specific shRNA and a very low DOX content, which simultaneously activated an intrinsic apoptotic pathway. A modified branched polyethylenimine (PEI 10kDa) was grafted through polyethylene glycol (PEG) linker to carboxylated single-walled carbon nanotubes (SWCNT) to serve as a vehicle for shRNA delivery. The SWNT-PEG-PEI conjugate was covalently attached to AS1411 aptamer as the nucleolin ligand to target the co-delivery system to the tumor cells overexpressing nucleolin receptors on their surface. The final vehicle was eventually obtained after intercalation of DOX with pBcl-xL shRNA-SWCNT-PEG-10-10%PEI-Apt. Cell viability assay, GFP expression and transfection experiment against L929 (-nucleolin) and AGS (+nucleolin) cells illustrated that the tested targeted delivery system inhibited the growth of nucleolin-abundant gastric cancer cells with strong cell selectivity. Subsequently, we illustrated that the combination treatment of the selected shRNAs and DOX had excellent tumoricidal efficacy as verified by MTT assay. Furthermore, very low concentration of DOX, approximately 58-fold lower than its IC50 concentration, was used which could mitigate toxic side effects of DOX. Overall, our work revealed that combination of shRNA-mediated gene-silencing strategy with chemotherapeutic agents constitutes a valuable and safe approach for antitumor activity.

A specific environment-sensitive near-infrared fluorescent turn-on probe for synergistic enhancement of anticancer activity of a chemo-drug

A near-infrared fluorescent turn-on probe has been reported for specific HER2 imaging and synergistic enhancement of anticancer activity of doxorubicin.

A Novel Danshensu Derivative Prevents Cardiac Dysfunction and Improves the Chemotherapeutic Efficacy of Doxorubicin in Breast Cancer Cells

Doxorubicin (Dox) is an anthracycline antibiotic widely used in clinics as an anticancer agent. However, the use of Dox is limited by its cardiotoxicity. We have previously shown that a Danshensu (DSS) derivative, ADTM, displayed strong cardioprotective effects. With improved chemical stability and activity, a novel DSS derivative, D006, based on the structure of ADTM, was synthesized. In the present study, the protective effects of D006, indexed by attenuation of the cardiotoxicity induced by Dox as well as chemosensitizing effects that increase the antitumor activity of Dox, were investigated. Our results showed that D006 was more potent than either parental compound, or their use in combination, in ameliorating Dox-induced toxicity in H9c2 cells. In our zebrafish model, D006, but not DSS, alone significantly preserved the ventricular function of zebrafish after Dox treatment. Moreover, D006 upregulated mitochondrial biogenesis and increased mtDNA copy number after Dox treatment of H9c2 cells. D006 promoted the expression of HO-1 protein in a time-dependent manner while the HO-1 inhibitor, Znpp, reversed the protective effects of D006. In human breast tumor MCF-7 cells, D006 enhanced Dox-induced cytotoxicity by increasing apoptosis. In conclusion, our results indicate that a new DSS derivative exhibits promising protective effects against Dox-induced cardiotoxicity both in vivo and in vitro, an effect at least partially mediated by induction of HO-1 expression and the activation of mitochondrial biogenesis. Meanwhile, D006 also potentiated the anti-cancer effects of Dox in breast tumor cells.

Doxorubicin-induced chronic dilated cardiomyopathy-the apoptosis hypothesis revisited

The chemotherapeutic agent doxorubicin (DOX) has significantly increased survival rates of pediatric and adult cancer patients. However, 10% of pediatric cancer survivors will 10-20 years later develop severe dilated cardiomyopathy (DCM), whereby the exact molecular mechanisms of disease progression after this long latency time remain puzzling. We here revisit the hypothesis that elevated apoptosis signaling or its increased likelihood after DOX exposure can lead to an impairment of cardiac function and cause a cardiac dilation. Based on recent literature evidence, we first argue why a dilated phenotype can occur when little apoptosis is detected. We then review findings suggesting that mature cardiomyocytes are protected against DOX-induced apoptosis downstream, but not upstream of mitochondrial outer membrane permeabilisation (MOMP). This lack of MOMP induction is proposed to alter the metabolic phenotype, induce hypertrophic remodeling, and lead to functional cardiac impairment even in the absence of cardiomyocyte apoptosis. We discuss findings that DOX exposure can lead to increased sensitivity to further cardiomyocyte apoptosis, which may cause a gradual loss in cardiomyocytes over time and a compensatory hypertrophic remodeling after treatment, potentially explaining the long lag time in disease onset. We finally note similarities between DOX-exposed cardiomyocytes and apoptosis-primed cancer cells and propose computational system biology as a tool to predict patient individual DOX doses. In conclusion, combining recent findings in rodent hearts and cardiomyocytes exposed to DOX with insights from apoptosis signal transduction allowed us to obtain a molecularly deeper insight in this delayed and still enigmatic pathology of DCM.