Doxorubicin induces cytotoxicity through upregulation of pERK-dependent ATF3

Multimodal Mass Spectrometry Imaging of an Osteosarcoma Multicellular Tumour Spheroid Model to Investigate Drug-Induced Response

A multimodal mass spectrometry imaging (MSI) approach was used to investigate the chemotherapy drug-induced response of a Multicellular Tumour Spheroid (MCTS) 3D cell culture model of osteosarcoma (OS). The work addresses the critical demand for enhanced translatable early drug discovery approaches by demonstrating a robust spatially resolved molecular distribution analysis in tumour models following chemotherapeutic intervention. Advanced high-resolution techniques were employed, including desorption electrospray ionisation (DESI) mass spectrometry imaging (MSI), to assess the interplay between metabolic and cellular pathways in response to chemotherapeutic intervention. Endogenous metabolite distributions of the human OS tumour models were complemented with subcellularly resolved protein localisation by the detection of metal-tagged antibodies using Imaging Mass Cytometry (IMC). The first application of matrix-assisted laser desorption ionization-immunohistochemistry (MALDI-IHC) of 3D cell culture models is reported here. Protein localisation and expression following an acute dosage of the chemotherapy drug doxorubicin demonstrated novel indications for mechanisms of region-specific tumour survival and cell-cycle-specific drug-induced responses. Previously unknown doxorubicin-induced metabolite upregulation was revealed by DESI-MSI of MCTSs, which may be used to inform mechanisms of chemotherapeutic resistance. The demonstration of specific tumour survival mechanisms that are characteristic of those reported for in vivo tumours has underscored the increasing value of this approach as a tool to investigate drug resistance.

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

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

CEBP-β and PLK1 as Potential Mediators of the Breast Cancer/Obesity Crosstalk: In Vitro and In Silico Analyses

Over the last two decades, obesity has reached pandemic proportions in several countries, and expanding evidence is showing its contribution to several types of malignancies, including breast cancer (BC). The conditioned medium (CM) from mature adipocytes contains a complex of secretes that may mimic the obesity condition in studies on BC cell lines conducted in vitro. Here, we report a transcriptomic analysis on MCF-7 BC cells exposed to adipocyte-derived CM and focus on the predictive functional relevance that CM-affected pathways/processes and related biomarkers (BMs) may have in BC response to obesity. CM was demonstrated to increase cell proliferation, motility and invasion as well as broadly alter the transcript profiles of MCF-7 cells by significantly modulating 364 genes. Bioinformatic functional analyses unraveled the presence of five highly relevant central hubs in the direct interaction networks (DIN), and Kaplan-Meier analysis sorted the CCAAT/enhancer binding protein beta (CEBP-β) and serine/threonine-protein kinase PLK1 (PLK1) as clinically significant biomarkers in BC. Indeed, CEBP-β and PLK1 negatively correlated with BC overall survival and were up-regulated by adipocyte-derived CM. In addition to their known involvement in cell proliferation and tumor progression, our work suggests them as a possible "deus ex machina" in BC response to fat tissue humoral products in obese women.

A Synergistic pH-Responsive Serum Albumin-Based Drug Delivery System Loaded with Doxorubicin and Pentacyclic Triterpene Betulinic Acid for Potential Treatment of NSCLC

Nanosized drug delivery systems (DDS) have been studied as a novel strategy against cancer due to their potential to simultaneously decrease drug inactivation and systemic toxicity and increase passive and/or active drug accumulation within the tumor(s). Triterpenes are plant-derived compounds with interesting therapeutic properties. Betulinic acid (BeA) is a pentacyclic triterpene that has great cytotoxic activity against different cancer types. Herein, we developed a nanosized protein-based DDS of bovine serum albumin (BSA) as the drug carrier combining two compounds, doxorubicin (Dox) and the triterpene BeA, using an oil-water-like micro-emulsion method. We used spectrophotometric assays to determine protein and drug concentrations in the DDS. The biophysical properties of these DDS were characterized using dynamic light scattering (DLS) and circular dichroism (CD) spectroscopy, confirming nanoparticle (NP) formation and drug loading into the protein structure, respectively. The encapsulation efficiency was 77% for Dox and 18% for BeA. More than 50% of both drugs were released within 24 h at pH 6.8, while less drug was released at pH 7.4 in this period. Co-incubation viability assays of Dox and BeA alone for 24 h demonstrated synergistic cytotoxic activity in the low μM range against non-small-cell lung carcinoma (NSCLC) A549 cells. Viability assays of the BSA-(Dox+BeA) DDS demonstrated a higher synergistic cytotoxic activity than the two drugs with no carrier. Moreover, confocal microscopy analysis confirmed the cellular internalization of the DDS and the accumulation of the Dox in the nucleus. We determined the mechanism of action of the BSA-(Dox+BeA) DDS, confirming S-phase cell cycle arrest, DNA damage, caspase cascade activation, and downregulation of epidermal growth factor receptor (EGFR) expression. This DDS has the potential to synergistically maximize the therapeutic effect of Dox and diminish chemoresistance induced by EGFR expression using a natural triterpene against NSCLC.

α-Bisabolol Attenuates NF-κB/MAPK Signaling Activation and ER-Stress-Mediated Apoptosis by Invoking Nrf2-Mediated Antioxidant Defense Systems against Doxorubicin-Induced Testicular Toxicity in Rats

The present study investigated the effects of α-bisabolol on DOX-induced testicular damage in rats. Testicular damage was induced in rats by injecting DOX (12.5 mg/kg, i.p., single dose) into rats. α-Bisabolol (25 mg/kg, i.p.) was administered to the rats along with DOX pre- and co-treatment daily for a period of 5 days. DOX-injected rats showed a decrease in absolute testicular weight and relative testicular weight ratio along with concomitant changes in the levels/expression levels of oxidative stress markers and Nrf2 expression levels in the testis. DOX injection also triggered the activation of NF-κB/MAPK signaling and increased levels/expression levels of pro-inflammatory cytokines (TNF-α, IL-6, and IL-1β) and inflammatory mediators (iNOS and COX-2) in the testis. DOX triggered apoptosis, manifested by an increment in the expression levels of pro-apoptotic markers (Bax, Bcl2, cleaved caspase-3 and -9, and cytochrome-C) and a decline in the expression levels of anti-apoptotic markers (Bcl-xL and Bcl2) in the testis. Additionally, light microscopy revealed the changes in testicular architecture. α-Bisabolol rescued alterations in the testicular weight; restored all biochemical markers; modulated the expression levels of Nrf2-mediated antioxidant responses, NF-κB/MAPK signaling, endoplasmic reticulum (ER) stress, and apoptosis markers in DOX-injected testicular toxicity in rats. Based on our findings, it can be concluded that α-bisabolol has the potential to attenuate DOX-induced testicular injury by modifying NF-κB/MAPK signaling and the ER-stress-mediated mitochondrial pathway of apoptosis by invoking Nrf2-dependent antioxidant defense systems in rats. Based on the findings of the present study, α-bisabolol could be suggested for use as an agent or adjuvant with chemotherapeutic drugs to attenuate their deleterious effects of DOX on many organs including the testis. However, further regulatory toxicology and preclinical studies are necessary before making recommendations in clinical tests.

α-Bisabolol Attenuates Doxorubicin Induced Renal Toxicity by Modulating NF-κB/MAPK Signaling and Caspase-Dependent Apoptosis in Rats

Doxorubicin (DOX) is a well-known and effective antineoplastic agent of the anthracycline family. But, multiple organ toxicities compromise its invaluable therapeutic usage. Among many toxicity types, nephrotoxicity is one of the major concerns. In recent years many approaches, including bioactive agents of natural origin, have been explored to provide protective effects against chemotherapy-related complications. α-Bisabolol is a naturally occurring monocyclic sesquiterpene alcohol identified in the essential oils of various aromatic plants and possesses a wide range of pharmacological properties such as antioxidant, anti-inflammatory, analgesic, cardioprotective, antibiotic, anti-irritant, and anticancer activities. The present study aimed to evaluate the effects of α-Bisabolol on DOX-induced nephrotoxicity in Wistar male albino rats. Nephrotoxicity was induced in rats by injecting a single dose of DOX (12.5 mg/kg, i.p.), and the test compound, α-Bisabolol (25 mg/kg) was administered intraperitoneally along with DOX as a co-treatment daily for 5 days. DOX-injected rats showed reduction in body weight along with a concomitant fall in antioxidants and increased lipid peroxidation in the kidney. DOX-injection also increased levels/expressions of proinflammatory cytokines namely tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and interleukin-1β (IL-1β) and inflammatory mediators like inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) and activated nuclear factor kappa-B (NF-κB)/mitogen-activated protein kinases (MAPK) signaling in the kidney tissues. DOX also triggered apoptotic cell death, evidenced by the increased expression of pro-apoptotic markers like BCL2-Associated X Protein (Bax), cleaved caspase-3, caspase- 9, and cytochrome-C) and a decrease in the expressions of anti-apoptotic markers namely B-cell lymphoma 2 (Bcl2) and B-cell lymphoma-extra large (Bcl-xL) in the kidney. These biochemical alterations were additionally supported by light microscopic findings, which revealed structural alterations in the kidney. However, treatment with α-Bisabolol prevented body weight loss, restored antioxidants, mitigated lipid peroxidation, and inhibited the rise in proinflammatory cytokines, as well as favorably modulated the expressions of NF-κB/MAPK signaling and apoptosis markers in DOX-induced nephrotoxicity. Based on the results observed, it can be concluded that α-Bisabolol has potential to attenuate DOX-induced nephrotoxicity by inhibiting oxidative stress and inflammation mediated activation of NF-κB/MAPK signaling alongwith intrinsic pathway of apoptosis in rats. The study findings are suggestive of protective potential of α-Bisabolol in DOX associated nephrotoxicity and this could be potentially useful in minimizing the adverse effects of DOX and may be a potential agent or adjuvant for renal protection.

Thymoquinone alleviates doxorubicin induced acute kidney injury by decreasing endoplasmic reticulum stress, inflammation and apoptosis

Doxorubicin (DOX) is used as an anticancer drug despite its many side effects. Thymoquinone (THQ) is a plant-derived substance that exhibits antioxidant and anti-inflammatory properties. We investigated the protective effects of THQ on DOX induced nephrotoxicity in rats. Rats were divided into five groups of eight: group 1, untreated control; group 2, olive oil group given olive oil intraperitoneally (i.p.) for 14 days; group 3, THQ group given 10 mg/kg THQ i.p. for 14 days; group 4, DOX group given a single dose of 15 mg/kg DOX i.p. on day 7 of experiment; group 5, DOX + THQ given 10 mg/kg THQ i.p. for 14 days and 15 mg/kg DOX i.p. on day 7. Kidney tissues were evaluated for histopathology. Caspase-3, IL-17, GRP78 and TNF-α immunostaining was used to determine the expression levels of these proteins among the groups. The TUNEL method was used to determine the apoptotic index. Total antioxidant status (TAS), total oxidant status (TOS), and TNF-α and TGF-β1 levels in kidney tissue were measured using ELISA assay. Histopathologic damage, caspase-3, IL-17, GRP78 and TNF-α immunoreactivity, TUNEL positive cells, TOS, TNF-α and TGF-β1 levels were increased in group 4 compared to group 1. The TAS of group 4 decreased compared to group 1. We found decreased caspase-3, IL-17, GRP78 and TNF-α expressions and TUNEL positive cells in group 5 compared to group 4. In rats given DOX, THQ reduced kidney damage by suppressing endoplasmic reticulum stress, inflammation and apoptosis pathways.

Apoptotic and antioxidant effects in HCT-116 colorectal carcinoma cells by a spiro-acridine compound, AMTAC-06

BACKGROUND

Acridine compounds have been described as promising anticancer agents. Previous studies showed that (E)-1'-((4-chlorobenzylidene)amino)-5'-oxo-1',5'-dihydro-10H-spiro[acridine-9,2'-pyrrole]-4'-carbonitrile (AMTAC-06), a spiro-acridine compound, has antitumor activity on Ehrlich tumor and low toxicity. Herein, we investigated its antitumor effect against human cells in vitro.

METHODS

MTT assay was used to assess cytotoxicity of AMTAC-06 (3.125-200 µM) against tumor and non-tumor cells, and the half-maximal inhibitory concentration (IC₅₀) and the selectivity index (SI) were calculated. The effects on the cell cycle (propidium iodide-PI-staining), apoptosis (Annexin V-FITC/PI double staining by flow cytometry), and production of reactive oxygen species, ROS (DCFH assay) were also evaluated. Statistical analysis was achieved using ANOVA followed by Tukey's post-test.

RESULTS

AMTAC-06 showed higher cytotoxicity against colorectal carcinoma HCT-116 cells (IC₅₀: 12.62 µM). The SI showed that AMTAC-06 was more selective for HCT-116 cells (HaCaT SI: 1.41; PBMC SI: 0.62) than doxorubicin (HaCaT SI: 0.10; PBMC SI: 0.01). AMTAC-06 (15 and 30 µM) induced an increase in the sub-G1 peak (p < 0.000001) and cell cycle arrest in S phase (p = 0.003547). Moreover, treatment with this compound (15 and 30 µM) resulted in increased early (p < 0.000001) and late apoptotic cells (p < 0.000001). In addition, there was a reduction on ROS production (p < 0.000001).

CONCLUSIONS

AMTAC-06 presents anticancer activity against HCT-116 cells by regulating the cell cycle, inducing apoptosis and an antioxidant action.

Apoptosis induction in HeLa cervical cancer cell line by steroidal 16,17-seco-16,17a-dinitriles

Steroids are good candidates for drug development, thanks to their low general toxicity and possible structure modifications, connected with change of their activity. Several 16,17-secoandrost-4-ene-16,17a-dinitrile compounds were synthesized and screened for anticancer effect previously, including 6-oxo and 6-hydroxyimino compounds. This research is continued with the attempts for different synthetic strategy and evaluation of anticancer effect mechanism. Synthesis of 3-hydroxyimino compounds was successful, but inseparable mix of isomers was excluded from biological tests. Tested secodinitriles expressed cytotoxic effect on HeLa cervix cancer cells as a model system, with submicromolar to molar IC50 values, where 6-substituted derivatives were more effective. After 72 h treatment with equitoxic concentrations equal IC50 values of test compounds the mechanism of this effect was studied using flow cytometry and specific fluorescent dyes. Modest change in both G0/G1 and G2/M resting phases and change in mitochondrial membrane potential were noticed, while the most pronounced effect was apoptosis induction. Total apoptosis was in range 50.72-58.31 % in all samples of cells treated with secodinitriles, compared to 7.44 % in control samples. Total percent of dead cells, including both apoptotic and necrotic, ranged from 55.24 to 65.34 %, compared to 10.68 % in control. Selectivity towards cancer cells is very important feature of these compounds as leading compounds in the drug development for the treatment of cancers of steroid hormone-dependent tissues.

Computational prediction of CRISPR-impaired non-coding regulatory regions

Genome-wide CRISPR screens are becoming more widespread and allow the simultaneous interrogation of thousands of genomic regions. Although recent progress has been made in the analysis of CRISPR screens, it is still an open problem how to interpret CRISPR mutations in non-coding regions of the genome. Most of the tools concentrate on the interpretation of mutations introduced in gene coding regions. We introduce a computational pipeline that uses epigenomic information about regulatory elements for the interpretation of CRISPR mutations in non-coding regions. We illustrate our analysis protocol on the analysis of a genome-wide CRISPR screen in hTERT-RPE1 cells and reveal novel regulatory elements that mediate chemoresistance against doxorubicin in these cells. We infer links to established and to novel chemoresistance genes. Our analysis protocol is general and can be applied on any cell type and with different CRISPR enzymes.

ATF3 Modulates the Resistance of Breast Cancer Cells to Tamoxifen through an N6-Methyladenosine-Based Epitranscriptomic Mechanism

Tamoxifen has been used for years for treating estrogen receptor-positive breast cancer; drug resistance, however, constitutes one of the main challenges for this therapy. We found that the protein expression level of ATF3 is significantly higher in tamoxifen-resistant (TamR) MCF-7 cells than the corresponding parental cancer cells. In addition, ATF3 protein expression is positively correlated with the resistance of TamR MCF-7 cells to 4-hydroxytamoxifen (4-OHT). Mechanistically, elevated ATF3 protein expression in TamR MCF-7 cells results from a lower level of expression of YTHDF2, an m⁶A reader protein, and the ensuing stabilization and increased translational efficiency of ATF3 mRNA. Additionally, TamR MCF-7 cells exhibited decreased methylation at A131, a consensus motif site for m⁶A, in the 5'-untranslated region (5'-UTR) of ATF3 mRNA. Moreover, augmented ATF3 stimulates the expression of ABCB1, an efflux pump that confers drug resistance in breast cancer cells, and ATF3 itself is also positively regulated by adenylate kinase 4. Together, our results uncovered a novel molecular target for m⁶A modification (i.e., ATF3 mRNA) and the epitranscriptomic regulator for this target (i.e., YTHDF2). We also illustrated the role of ATF3 in drug resistance, revealed its downstream target (i.e., ABCB1), and suggested ATF3 as a candidate therapeutic target for overcoming drug resistance in cancer cells.

Doxorubicin sensitizes cancer cells to Smac mimetic via synergistic activation of the CYLD/RIPK1/FADD/caspase-8-dependent apoptosis

Smac/Diablo is a pro-apoptotic protein via interaction with inhibitors of apoptosis proteins (IAPs) to relieve their inhibition of caspases. Smac mimetic compounds (also known as antagonists of IAPs) mimic the function of Smac/Diablo and sensitize cancer cells to TNF-induced apoptosis. However, the majority of cancer cells are resistant to Smac mimetic alone. Doxorubicin is a widely used chemotherapeutic drug and causes adverse effect of cardiotoxicity in many patients. Therefore, it is important to find strategies of combined chemotherapy to increase chemosensitivity and reduce the adverse effects. Here, we report that doxorubicin synergizes with Smac mimetic to trigger TNF-mediated apoptosis, which is mechanistically distinct from doxorubicin-induced cell death. Doxorubicin sensitizes cancer cells including human pancreatic and colorectal cancer cells to Smac mimetic treatment. The combined treatment leads to synergistic induction of TNFα to initiate apoptosis through activating NF-κB and c-Jun signaling pathways. Knockdown of caspase-8 or knockout of FADD significantly blocked apoptosis synergistically induced by Smac mimetic and doxorubicin, but had no effect on cell death caused by doxorubicin alone. Moreover, Smac mimetic and doxorubicin-induced apoptosis requires receptor-interacting protein kinase 1 (RIPK1) and its deubiquitinating enzyme cylindromatosis (CYLD), not A20. These in vitro findings demonstrate that combination of Smac mimetic and doxorubicin synergistically triggers apoptosis through the TNF/CYLD/RIPK1/FADD/caspase-8 signaling pathway. Importantly, the combined treatment induced in vivo synergistic anti-tumor effects in the xenograft tumor model. Thus, the combined therapy using Smac mimetic and doxorubicin presents a promising apoptosis-inducing strategy with great potential for the development of anti-cancer therapy.

Adult Zebrafish Model for Screening Drug-Induced Kidney Injury

Drug-induced kidney injury is a serious safety issue in drug development. In this study, we evaluated the usefulness of adult zebrafish as a small in vivo system for detecting drug-induced kidney injury. We first investigated the effects of typical nephrotoxicants, gentamicin and doxorubicin, on adult zebrafish. We found that gentamicin induced renal tubular necrosis with increased lysosome and myeloid bodies, and doxorubicin caused foot process fusion of glomerular podocytes. These findings were similar to those seen in mammals, suggesting a common pathogenesis. Second, to further evaluate the performance of the model in detecting drug-induced kidney injury, adult zebrafish were treated with 28 nephrotoxicants or 14 nonnephrotoxicants for up to 4 days, euthanized 24 h after the final treatment, and examined histopathologically. Sixteen of the 28 nephrotoxicants and none of the 14 nonnephrotoxicants caused drug-induced kidney injury in zebrafish (sensitivity, 57%; specificity, 100%; positive predictive value, 100%; negative predictive value, 54%). Finally, we explored genomic biomarker candidates using kidneys isolated from gentamicin- and cisplatin-treated zebrafish using microarray analysis and identified 3 candidate genes, egr1, atf3, and fos based on increased expression levels and biological implications. The expression of these genes was upregulated dose dependently in cisplatin-treated groups and was > 25-fold higher in gentamicin-treated than in the control group. In conclusion, these results suggest that the adult zebrafish has (1) similar nephrotoxic response to those of mammals, (2) considerable feasibility as an experimental model for toxicity studies, and (3) applicability to pathological examination and genomic biomarker evaluation in drug-induced kidney injury.

Thymoquinone Selectively Induces Hepatocellular Carcinoma Cell Apoptosis in Synergism With Clinical Therapeutics and Dependence of p53 Status

Thymoquinone (TQ) is a natural compound extracted from the black seeds of Nigella sativa Linn. belonging to the Ranunculaceae family. TQ exhibits anti-inflammatory and antineoplastic activities against various cancers. Many therapeutics in hepatocellular carcinoma (HCC) treatments, such as doxorubicin (DOX) and cisplatin (DDP), exhibit considerable side effects on patients. We investigated cytotoxic effects of TQ, alone or in combination with DDP and DOX to HCC cells. TQ exhibited selective killing to HCC HepG2 and SMMC-7721 cells, but relatively low toxicity to normal liver HL-7702 cells. Importantly, when used with DOX or DDP, TQ showed synergistic inhibition of HCC cells, but not HL-7702 cells. We also discovered that Hep3B cells with a p53 null status were more sensitive to TQ than HepG2 and SMMC-7721 cells harboring wild type p53. Consistently, shRNA-mediated p53 silencing in HepG2 cells dramatically enhanced TQ-induced apoptosis, measured by caspase 3 and PARP cleavage. Furthermore, TQ-stimulated increase of reactive oxygen species (ROS) in p53-depleted cells was more pronounced than that in cells with intact p53. In summary, we discovered that TQ synergistically improves the anti-cancer activity of DOX and DDP, and loss of p53 sensitizes HCC cells to TQ-induced apoptosis.

MicroRNA-874-3p Aggravates Doxorubicin-Induced Renal Podocyte Injury via Targeting Methionine Sulfoxide Reductase B3

Clinical application of doxorubicin (Dox) is limited due to its serious side effects including nephrotoxicity, and kidney podocytes play important roles in renal diseases. MicroRNAs (miRNAs) are critical regulators associated with human diseases. The purpose of this study was to explore a novel target in adjusting Dox-induced renal podocyte injury. Through a double luciferase reporter gene experiment, it was found that miR-874-3p directly targeted methionine sulfoxide reductase B3 (MsrB3). During the tests of miR-874-3p inhibitor and MsrB3 siRNA in human podocytes or miR-874-3p antagomir in mice, we found that the expression levels of downstream oxidative stress and apoptosis-related proteins were regulated by miR-874-3p/MsrB3 signal to alleviate or aggravate renal podocyte injury. The data in the present work showed that miR-874-3p aggravated Dox-caused renal podocyte injury by promoting apoptosis and oxidative damage via inhibiting MsrB3. Therefore, miR-874-3p/MsrB3 should be considered as a new therapeutic target in controlling renal podocyte injury induced by Dox.

New A-homo lactam D-homo lactone androstane derivative: Synthesis and evaluation of cytotoxic and anti-inflammatory activities in vitro

This paper describes the synthesis of a new A-homo lactam D-homo lactone androstane derivative from dehydroepiandrosterone. To evaluate the impact of the introduction of nitrogen in the parental scaffold on biological activity, a new androstane enamide-type lactam derivative was prepared and characterized. The new compound as well as starting compounds were screened for cytotoxic, anti-angiogenic and anti-inflammatory activities using several human cancer cell lines (MCF-7, MDA-MB-231, PC3, CEM, G-361, HeLa), endothelial (HUVEC) and non-tumour (MRC-5 and BJ) cell lines. Strong cytotoxic and anti-inflammatory activity with a broad therapeutical window was demonstrated by the A-homo lactam D-homo lactone androstane derivative. The induction of apoptosis in treated PC3 cultures was confirmed using apoptotic morphology screening and a fluorescent double-staining method. New A-homo lactam D-homo lactone androstane derivative induced apoptosis more than the tested reference compounds, Formestane and Doxorubicin. An in silico ADME analysis showed that the compounds possess drug-like properties.

An Extract of Transgenic Senna obtusifolia L. Hairy Roots with Overexpression of PgSS1 Gene in Combination with Chemotherapeutic Agent Induces Apoptosis in the Leukemia Cell Line

Many biologically-active plant-derived compounds have therapeutic or chemopreventive effects. The use of plant in vitro cultures in conjunction with modern genetic engineering techniques allows greater amounts of valuable secondary metabolites to be obtained without interfering with the natural environment. This work presents the first findings concerning the acquisition of transgenic hairy roots of Senna obtusifolia overexpressing the gene encoding squalene synthase 1 from Panax ginseng (PgSS1) (SOPSS hairy loot lines) involved in terpenoid biosynthesis. Our results confirm that one of PgSS1-overexpressing hairy root line extracts (SOPSS2) possess a high cytotoxic effect against a human acute lymphoblastic leukemia (NALM6) cell line. Further analysis of the cell cycle, the expression of apoptosis-related genes (TP53, PUMA, NOXA, BAX) and the observed decrease in mitochondrial membrane potential also confirmed that the SOPSS2 hairy root extract displays the highest effects; similar results were also obtained for this extract combined with doxorubicin. The high cytotoxic activity, observed both alone or in combination with doxorubicin, may be due to the higher content of betulinic acid as determined by HPLC analysis. Our results suggest synergistic effects of tested extract (betulinic acid in greater amount) with doxorubicin which may be used in the future to develop new effective strategies of cancer chemosensitization.

The Adjuvant Effect of Squalene, an Active Ingredient of Functional Foods, on Doxorubicin-Treated Allograft Mice

Many functional foods or physiologically active ingredients derived from plants and animals are actively being investigated for their role in chronic disease prevention. Squalene (SQ) is found as active ingredient in the functional foods predominantly present in olive oil and shark liver oil. It is known that during chemotherapy anticancer drugs induce inflammation. SQ has been thought to prevent and suppress inflammation; however, there is little direct evidence available. We examined the adjuvant effect of SQ on tumor-transplanted mice along with anticancer drug doxorubicin (DOX). SQ significantly suppressed the DOX-induced increase in prostaglandin E₂ (PGE₂) concentration (P < 0.05) in plasma of tumor-bearing mice. SQ inhibited the numbers of writhing response (P < 0.05), formalin-induced pain and decreased COX-2 and substance P expression in the tumor tissue compared to control mice and also enhanced the antitumor efficacy of DOX in allograft mice. Thus, SQ reduces inflammation through modulation of PGE₂ production indicating its potential as an adjuvant during chemotherapy in tumor-bearing mice.

β-Lapachone protects against doxorubicin-induced nephrotoxicity via NAD+/AMPK/NF-kB in mice

β-Lapachone (B-LAP) is a natural naphtaquinone with established anti-oxidative stress and anti-cancer activities. We aimed to investigate B-LAP protective potential against doxorubicin (DOX)-induced nephrotoxicity in mice. The mice received an oral dose of B-LAP followed by a single intraperitoneal injection of 20 mg/kg DOX a day later. They were then treated for 4 days with 1.25 mg/kg, 2.5 mg/kg, and 5 mg/kg doses of B-LAP. Renal levels of NAD+/NADH ratios, p-AMPKα, p-NF-κB p65, inducible nitric oxide synthase (iNOS), tumor necrosis factor alpha (TNF-α), interleukin 6 (IL-6) along with renal expressions of TNF-α, IL-1β, and IL-6 were examined. Serum levels of kidney function markers as well as renal histopathology were also investigated. In addition to increasing the activities of p-AMPKα, B-LAP elevated NAD+/NADH ratios in the kidneys and decreased the renal levels of nuclear p-NF-κB and its correspondent downstream effectors TNF-α, IL-1β, IL-6, and iNOS in the kidneys. Also, B-LAP effectively ameliorated renal architectural changes and attenuated serum levels of urea, creatinine, and cystatin C. Collectively, these findings suggest the protective actions of B-LAP against DOX-induced nephrotoxicity in mice.

siRNA-Conjugated Nanoparticles to Treat Ovarian Cancer

Ovarian cancer is the fifth-most lethal cancer among women due to a lack of early detection and late-stage treatment options, and it is responsible for more than 14,000 deaths each year in the United States. Recently, there have been advances in RNA interference therapy, specifically with small interfering RNA (siRNA), to reduce tumor burden for ovarian cancer via gene down-regulation. However, delivery of siRNA poses its own challenges, as siRNA is unstable in circulation, is unable to be effectively internalized by cells, and may cause toxicity in off-target sites. To address such challenges, nanoparticle carriers have emerged as delivery platforms for the biocompatible, targeted delivery of siRNA-based therapies. Several preclinical studies have shown the promising effects of siRNA therapy to reduce chemotherapy resistance and proliferation of ovarian cancer cells. This review evaluates the recent advances, clinical applications, and future potential of nanoparticle-mediated delivery of siRNA therapeutics to target genes implicated in ovarian cancer.

Treatment with DHA Modifies the Response of MDA-MB-231 Breast Cancer Cells and Tumors from nu/nu Mice to Doxorubicin through Apoptosis and Cell Cycle Arrest

Background

Docosahexaenoic acid (DHA) has been shown to reduce growth of breast cancer cells in vitro and in vivo; it may also benefit the action of cytotoxic cancer drugs. The mechanisms for these observations are not completely understood.

Objectives

We sought to explore how pretreatment of MDA-MB-231 breast cancer cells with DHA alters gene expression with doxorubicin (DOX) treatment and confirm that feeding DHA to tumor-bearing nu/nu mice improves the efficacy of DOX.

Methods

MDA-MB-231 cells were subjected to 4 conditions: a control mixture of 40 μM linoleic and 40 μM oleic acid (OALA), DHA (60 μM plus OALA), OALA DOX (0.41 μM), or DHA DOX (plus OALA) and assessed for effects on viability and function. Female nu/nu mice (6 wk old) bearing MDA-MB-231 tumors were randomly assigned to a nutritionally complete diet (20 g ± 2.8 g DHA/100 g diet) containing a polyunsaturated:saturated fat ratio of 0.5, with or without injections 2 times/wk of 5 mg DOX/kg for 4 wk.

Results

Microarray and protein analysis indicated that DHA DOX cells, compared with OALA DOX, had upregulated expression of apoptosis genes, Caspase-10 (1.3-fold), Caspase-9 (1.4-fold), and Receptor (TNFRSF)-interacting serine-threonine kinase 1 (RIPK1) (1.2-fold), while downregulating cell cycle genes, Cyclin B1 (-2.1-fold), WEE1 (-1.6-fold), and cell division cycle 25 homolog C (CDC25C) (-1.8-fold) (P < 0.05). DHA DOX-treated mice had 50% smaller tumors than control mice (P < 0.05). Analysis of proapoptotic proteins from tumors of DHA DOX mice showed increased Caspase-10 (by 68%) and BH3 interacting domain death agonist (Bid) (by 50%), decreased B-cell CLL/lymphoma 2 (BCL2) (by 24%), and decreased cell cycle proteins Cyclin B1 and Cdc25c (both by 42%), compared with control mice (P < 0.05).

Conclusions

Supplementation with DHA facilitates the action of DOX in MDA-MB-231 cells and in nu/nu mice, which may occur via amplification of the effect of DOX on apoptosis and cell cycle genes.

Protective effect of irbesartan against doxorubicin-induced nephrotoxicity in rats: implication of AMPK, PI3K/Akt, and mTOR signaling pathways

Nephrotoxicity is one of the serious undesirable effects related to doxorubicin (DOX). Herein, we have investigated the potential protective effect of irbesartan (IRB) against chronic nephrotoxicity induced by DOX, and the implication of different mechanistic pathways underlying these effects. Rats were treated with either DOX (2.5 mg/kg i.p., 3 times/week) for 2 weeks, and (or) IRB (40 mg/kg, daily) for 3 weeks. IRB prohibited nephrotoxicity induced by DOX, which was evident by the increase in blood urea nitrogen and creatinine levels and histopathological changes. IRB improved DOX-induced alterations in oxidative status by diminishing lipid peroxidation and upregulating the antioxidant enzymes. Also, upon DOX treatment, the renal expression of tumor necrosis factor-α, interleukin-6, and caspase-3 were significantly increased; IRB diminished DOX-induced alterations in these parameters. Moreover, DOX significantly decreased the expression level of AMP-activated protein kinase (AMPK). Meanwhile, DOX induced activation of phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt/PKB) and mammalian target of rapamycin (mTOR) pathways that cross talked with AMPK. On the contrary, IRB successfully counterbalanced all these effects. Collectively, these outcomes suggest that the modulation of AMPK, PI3K, Akt, and mTOR pathways plays a critical role in conferring the protective effects of IRB against DOX nephrotoxicity.

Flavonoids modulate multidrug resistance through wnt signaling in P-glycoprotein overexpressing cell lines

BACKGROUND

Wnt signaling has been linked with P-glycoprotein (P-gp) overexpression and which was mainly mediated by β-catenin nuclear translocation. Flavonoids have already been reported as modulators of the Wnt/β-catenin pathway and hence they may serve as promising agents in the reversal of P-gp mediated cancer multi drug resistance (MDR).

METHODS

In this study, we screened selected flavonoids against Wnt/β-catenin signaling molecules. The binding interaction of flavonoids (theaflavin, quercetin, rutin, epicatechin 3 gallate and tamarixetin) with GSK 3β was determined by molecular docking. Flavonoids on P-gp expression and the components of Wnt signaling in drug-resistant KBCH^R8-5 cells were analyzed by western blotting and qRT-PCR. The MDR reversal potential of these selected flavonoids against P-gp mediated drug resistance was analyzed by cytotoxicity assay in KBCH^R8-5 and MCF7/ADR cell lines. The chemosensitizing potential of flavonoids was further analyzed by observing cell cycle arrest in KBCH^R8-5 cells.

RESULTS

In this study, we observed that the components of Wnt/β-catenin pathway such as Wnt and GSK 3β were activated in multidrug resistant KBCH^R8-5 cell lines. All the flavonoids selected in this study significantly decreased the expression of Wnt and GSK 3β in KBCH^R8-5 cells and subsequently modulates P-gp overexpression in this drug-resistant cell line. Further, we observed that these flavonoids considerably decreased the doxorubicin resistance in KBCH^R8-5 and MCF7/ADR cell lines. The MDR reversal potential of flavonoids were found to be in the order of theaflavin > quercetin > rutin > epicatechin 3 gallate > tamarixetin. Moreover, we observed that flavonoids pretreatment significantly induced the doxorubicin-mediated arrest at the phase of G2/M. Further, the combinations of doxorubicin with flavonoids significantly modulate the expression of drug response genes in KBCH^R8-5 cells.

CONCLUSION

The present findings illustrate that the studied flavonoids significantly enhances doxorubicin-mediated cell death through modulating P-gp expression pattern by targeting Wnt/β-catenin signaling in drug-resistant KBCH^R8-5 cells.

EGR1 is essential for deoxynivalenol-induced G2/M cell cycle arrest in HepG2 cells via the ATF3ΔZip2a/2b-EGR1-p21 pathway

Deoxynivalenol (DON) is a type B trichothecene mycotoxin that exerts multiple toxic effects on plants, animals and humans. Several reports have shown that DON leads to G2/M cell cycle arrest. However, its molecular mechanism is still unclear. In this study, we showed that DON induced strong G2/M cell cycle arrest in HepG2 cells, and the cell cycle-inhibitory protein p21 was highly upregulated by DON. Further analysis showed that the cell cycle regulating gene EGR1 was highly induced by DON and that EGR1 knockdown abolished the upregulation of p21 and G2/M cell cycle arrest. Furthermore, we showed that the induction of EGR1 was regulated by the stress-responsive transcription factor ATF3. ATF3ΔZip2a/2b, which is a DNA binding domain truncated isoform of ATF3, was upregulated by DON. ATF3 knockdown weakened the expression induction of EGR1 and G2/M cell cycle arrest by DON. Moreover, the upregulation of ATF3ΔZip2a/2 highly depended on the enhanced presence of histones H3K9ac and H3K27ac. H3K9ac and H3K27ac were enriched at the promoter region of ATF3 following the DON treatment, and the knocking down of the genes responsible for H3K9ac and H3K27ac abolished the upregulation of ATF3 by DON. In summary, we found that DON induced G2/M cell cycle arrest by sequentially inducing the expression of ATF3ΔZip2a/2b, EGR1 and p21, and EGR1 played an essential role in this process, which is a novel molecular mechanism of cell cycle arrest by DON and is important for understanding its toxicology.

Toxicity and Safety Evaluation of Doxorubicin-Loaded Cockleshell-Derived Calcium Carbonate Nanoparticle in Dogs

Doxorubicin (DOX) is a potent anticancer agent with cytotoxic effects which limit its clinical usage. This effect is due to its nonselective nature causing injury to the cells as a result of reactive free oxygen radical's release. Cockleshell-derived calcium carbonate nanoparticle (CS-CaCO3NP) is a pH-responsive carrier with targeted delivery potentials. This study aimed at evaluating the toxicity effects of repeated dose administration of DOX-loaded CS-CaCO3NP in healthy dogs. Fifteen dogs with an average body weight of 15 kg were randomized equally into 5 groups. Dogs were subjected to 5 doses at every 3-week interval with (i) normal saline, (ii) DOX, 30 mg/m2, and the experimental groups: CS-CaCO3NP-DOX at (iii) high dose, 50 mg/m2, (iv) clinical dose, 30 mg/m2, and (v) low dose, 20 mg/m2. Radiographs, electrocardiography, and blood samples were collected before every treatment for haematology, serum biochemistry, and cardiac injury assessment. Heart and kidney tissues were harvested after euthanasia for histological and ultrastructural evaluation. The cumulative dose of DOX 150 mg/m2 over 15 weeks revealed significant effects on body weight, blood cells, functional enzymes, and cardiac injury biomarkers with alterations in electrocardiogram, myocardium, and renal tissue morphology. However, the dogs given CS-CaCO3NP-DOX 150 mg/m2 and below did not show any significant change in toxicity biomarker as compared to those given normal saline. The study confirmed the safety of repeated dose administration of CS-CaCO3NP-DOX (30 mg/m2) for 5 cycles in dogs. This finding offers opportunity to dogs with cancer that might require long-term administration of DOX without adverse effects.

Activating Transcription Factor 3 as a Novel Regulator of Chemotherapy Response in Breast Cancer

Anthracyclines, such as doxorubicin, are used as first-line chemotherapeutics, usually in combination therapies, for the treatment of advanced breast cancer. While these drugs have been successful therapeutic options, their use is limited due to serious drug related toxicities and acquired tumor resistance. Uncovering the molecular mechanisms that mediate doxorubicin's cytotoxic effect will lead to the identification of novel more efficacious combination therapies and allow for reduced doses of doxorubicin to be administered while maintaining efficacy. In our study, we demonstrate that activating transcription factor (ATF) 3 expression was upregulated by doxorubicin treatment in a representative panel of human breast cancer cell lines MCF7 and MDA-MB-231. We have also shown that doxorubicin treatment can induce ATF3 expression in ex vivo human breast and ovarian tumor samples. The upregulation of ATF3 in the cell lines was regulated by multiple cellular mechanisms including the activation of JNK and ATM signaling pathways. Importantly, loss of ATF3 expression resulted in reduced sensitivity to doxorubicin treatment in mouse embryonic fibroblasts. Through a 1200 FDA-approved compound library screen, we identified a number of agents whose cytotoxicity is dependent on ATF3 expression that also enhanced doxorubicin induced cytotoxicity. For example, the combination of the HDAC inhibitor vorinostat or the nucleoside analogue trifluridine could synergistically enhance doxorubicin cytotoxicity in the MCF7 cell line. Synergy in cell lines with the combination of ATF3 inducers and patients with elevated basal levels of ATF3 shows enhanced response to chemotherapy. Taken together, our results demonstrate a role for ATF3 in mediating doxorubicin cytotoxicity and provide rationale for the combination of ATF3-inducing agents with doxorubicin as a novel therapeutic approach.

Stress-inducible gene Atf3 in the noncancer host cells contributes to chemotherapy-exacerbated breast cancer metastasis

Chemotherapy is a double-edged sword. It is anticancer because of its cytotoxicity. Paradoxically, by increasing chemoresistance and cancer metastasis, it is also procancer. However, the underlying mechanisms for chemotherapy-induced procancer activities are not well understood. Here we describe the ability of paclitaxel (PTX), a frontline chemotherapeutic agent, to exacerbate metastasis in mouse models of breast cancer. We demonstrate that, despite the apparent benefit of reducing tumor size, PTX increased the circulating tumor cells in the blood and enhanced the metastatic burden at the lung. At the primary tumor, PTX increased the abundance of the tumor microenvironment of metastasis, a landmark microanatomical structure at the microvasculature where cancer cells enter the blood stream. At the metastatic lung, PTX improved the tissue microenvironment (the "soil") for cancer cells (the "seeds") to thrive; these changes include increased inflammatory monocytes and reduced cytotoxicity. Importantly, these changes in the primary tumor and the metastatic lung were all dependent on Atf3, a stress-inducible gene, in the noncancer host cells. Together, our data provide mechanistic insights into the procancer effect of chemotherapy, explaining its paradox in the context of the seed-and-soil theory. Analyses of public datasets suggest that our data may have relevance to human cancers. Thus, ATF3 in the host cells links a chemotherapeutic agent-a stressor-to immune modulation and cancer metastasis. Dampening the effect of ATF3 may improve the efficacy of chemotherapy.

Etoposide induced cytotoxicity mediated by ROS and ERK in human kidney proximal tubule cells

Etoposide (ETO) is a commonly used chemotherapeutic drug that inhibits topoisomerase II activity, thereby leading to genotoxicity and cytotoxicity. However, ETO has limited application due to its side effects on normal organs, especially the kidney. Here, we report the mechanism of ETO-induced cytotoxicity progression in human kidney proximal tubule (HK-2) cells. Our results show that ETO perpetuates DNA damage, activates mitogen-activated protein kinase (MAPK), and triggers morphological changes, such as cell and nuclear swelling. When NAC, a well-known reactive oxygen species (ROS) scavenger, is co-treated with ETO, it inhibits an ETO-induced increase in mitochondrial mass, mitochondrial DNA (ND1 and ND4) copy number, intracellular ATP level, and mitochondrial biogenesis activators (TFAM, PGC-1α and PGC-1β). Moreover, co-treatment with ETO and NAC inhibits ETO-induced necrosis and cell swelling, but not apoptosis. Studies using MAPK inhibitors reveal that inhibition of extracellular signal regulated kinase (ERK) protects ETO-induced cytotoxicity by inhibiting DNA damage and caspase 3/7 activity. Eventually, ERK inhibitor treated cells are protected from ETO-induced nuclear envelope (NE) rupture and DNA leakage through inhibition of caspase activity. Taken together, these data suggest that ETO mediates cytotoxicity in HK-2 cells through ROS and ERK pathways, which highlight the preventive avenues in ETO-induced cytotoxicity in kidney.

Fullerenol nanoparticles as a new delivery system for doxorubicin

Fullerenol as a promising intracellular targeting carrier for the efficient delivery of antitumor drugs into tumor cells.

Protective effects of madecassoside against Doxorubicin induced nephrotoxicity in vivo and in vitro

Madecassoside (MA), a triterpenoid saponin isolated from C. asitica, exerts various pharmacological activity including antioxidative and antinflammatory. Doxorubicin (DOX), a common chemotherapeutic drug, has been reported to induce numerous toxic side effects including renal-toxicity. We hypothesized that MA administration may decrease renal-toxicity caused by DOX. In this study, we investigated this hypothesis by introducing MA and DOX into the culture of Human Proximal Tubule Cells HK-2 and mice model. Our in vivo study demonstrated that MA (12 mg/kg), treatment for two weeks attenuated DOX-induced renal injury via protecting renal function, recovering antioxidant enzyme activity, inhibiting Bax, p-ERK1/2, NF-κB p65, iNOS expression and increasing Bcl-2 expression. Similar findings were obtained in our in vitro studies with treatment of DOX and/or MA. Further studies with application of iNOS inhibitor and ERK1/2 kinase inhibitor indicated that the inhibitory effects of MA on DOX-induced apoptosis and inflammation might be mediated by the suppression of the activation of cleaved caspase-3, ERK1/2 pathways, NF-κB p65 and NO production. These results suggest that MA is a promising protective agent for DOX-induced renal toxicity and can be a potential candidate to protect against renal toxicity in DOX-treated cancer patients.

Structural and functional analysis of cell adhesion and nuclear envelope nano-topography in cell death

The cell death mechanisms of necrosis and apoptosis generate biochemical and morphological changes in different manners. However, the changes that occur in cell adhesion and nuclear envelope (NE) topography, during necrosis and apoptosis, are not yet fully understood. Here, we show the different alterations in cell adhesion function, as well as the topographical changes occurring to the NE, during the necrotic and apoptotic cell death process, using the xCELLigence system and atomic force microscopy (AFM). Studies using xCELLigence technology and AFM have shown that necrotic cell death induced the expansion of the cell adhesion area, but did not affect the speed of cell adhesion. Necrotic nuclei showed a round shape and presence of nuclear pore complexes (NPCs). Moreover, we found that the process of necrosis in combination with apoptosis (termed nepoptosis here) resulted in the reduction of the cell adhesion area and cell adhesion speed through the activation of caspases. Our findings showed, for the first time, a successful characterization of NE topography and cell adhesion during necrosis and apoptosis, which may be of importance for the understanding of cell death and might aid the design of future drug delivery methods for anti-cancer therapies.

Activating transcription factor 3 represses inflammatory responses by binding to the p65 subunit of NF-κB

Activating transcription factor 3 (ATF3) is induced by inflammatory responses, cell death, cytokines, and oxidative stress conditions. ATF3 is a negative regulator in the Toll-like receptor 4 signalling pathway. The principal molecule in this pathway is nuclear factor κB (NF-κB) that translocates into the nucleus to initiate the transcription of inflammatory mediators. However, scarce data are available regarding the interaction of ATF3 and p65, a part of the NF-κB dimer. Therefore, we studied the mechanism of regulation of p65 by ATF3 in RAW 264.7 cells. First, LPS-mediated NF-κB activation was confirmed, and then the direct interaction of ATF3 and p65 was observed through immunoprecipitation (IP). The presence of histone deacetylase 1 (HDAC1) was also detected in the complex. In ATF3 deficient cells, NF-κB activity was up-regulated and HDAC1 was not detected by IP. These observations suggest that p65 is attenuated by ATF3 such that ATF3 recruits HDAC1 to the ATF3/p65 complex and facilitates the deacetylation of p65. Likewise, inflammatory response genes were induced by translocated NF-κB in ATF3-deficient cells. Cumulatively, we uncovered a novel mechanism for the negative regulation of NF-κB by ATF3 via direct interaction with p65.

Etoposide Induces Necrosis Through p53-Mediated Antiapoptosis in Human Kidney Proximal Tubule Cells

The p53 protein is an important transcription factor that modulates signaling pathways for both cell death and survival. Its antiapoptotic mechanisms that correlate with necrotic and apoptotic cell death are not well understood. Here, we report that etoposide promotes progression of the DNA damage response as well as necrotic morphological changes including plasma membrane rupture using carbon nanotube-tipped/atomic force microscopy (CNT/AFM) probes in human kidney proximal tubule (HK-2) cells. Inhibition of p53 abrogated cell cycle arrest and led to a decrease in the expression levels of repair proteins that were induced by DNA damage. Mitochondrial biogenesis and cytosolic production of reactive oxygen species were also reduced after p53 inhibition; the latter change induced mitochondrial superoxide accumulation and mitochondrial damage, which triggered the activation of caspase 3. Inhibition of p53 also led to a loss of cell adhesion and converted necrotic cell death to apoptotic cell death, with appreciable cell shrinkage and appearance of apoptotic bodies that were observed using CNT/AFM probes. Thus, our study demonstrated that p53 protects against apoptosis, and leads to etoposide-induced necrosis. These results are expected to aid in the understanding of mechanism of antiapoptosis and its relationship to cell death.

Sall2 is required for proapoptotic Noxa expression and genotoxic stress-induced apoptosis by doxorubicin

The Sall2 transcription factor is deregulated in several cancers; however, little is known about its cellular functions, including its target genes. Recently, we demonstrated that p53 directly regulates Sall2 expression under genotoxic stress. Here, we investigated the role of Sall2 in the context of cellular response to genotoxic stress. In addition, we further examined the Sall2-p53 relationship during genotoxic stress in primary mouse embryo fibroblasts (MEFs), which are derived from Sall2 knockout mice separately, or in combination with the p53ERTAM knock-in mice. We found that the levels of Sall2 mRNA and protein are dynamically modulated in response to doxorubicin. At early times of stress, Sall2 is downregulated, but increases under extension of the stress in a p53-independent manner. Based on caspase-3/7 activities, expression of cleaved poly (ADP-ribose) polymerase, expression of cleaved caspase-3 and induction of proapoptotic proteins, Sall2 expression was correlated with cellular apoptosis. Consequently, Sall2-/- MEFs have decreased apoptosis, which relates with increased cell viability in response to doxorubicin. Importantly, Sall2 was required for apoptosis even in the presence of fully activated p53. Searching for putative Sall2 targets that could mediate its role in apoptosis, we identified proapoptotic NOXA/PMAIP1 (phorbol-12-myristate-13-acetate-induced protein 1). We demonstrated that Sall2 positively regulates Noxa promoter activity. Conserved putative Sall2-binding sites at the NOXA promoter were validated in vitro by electrophoretic mobility shift assay and in vivo by ChIP experiments, identifying NOXA as a novel Sall2 target. In agreement, induction of Noxa protein and mRNA in response to doxorubicin was significantly decreased in Sall2-/- MEFs. In addition, studies in leukemia Jurkat T cells support the existence of the Sall2/Noxa axis, and the significance of this axis on the apoptotic response to doxorubicin in cancer cells. Our study highlights the relevance of Sall2 in the apoptotic response to extended genotoxic stress, which is important for understanding its role in normal physiology and disease.

Oxidative/Nitrative Stress and Inflammation Drive Progression of Doxorubicin-Induced Renal Fibrosis in Rats as Revealed by Comparing a Normal and a Fibrosis-Resistant Rat Strain

Chronic renal fibrosis is the final common pathway of end stage renal disease caused by glomerular or tubular pathologies. Genetic background has a strong influence on the progression of chronic renal fibrosis. We recently found that Rowett black hooded rats were resistant to renal fibrosis. We aimed to investigate the role of sustained inflammation and oxidative/nitrative stress in renal fibrosis progression using this new model. Our previous data suggested the involvement of podocytes, thus we investigated renal fibrosis initiated by doxorubicin-induced (5 mg/kg) podocyte damage. Doxorubicin induced progressive glomerular sclerosis followed by increasing proteinuria and reduced bodyweight gain in fibrosis-sensitive, Charles Dawley rats during an 8-week long observation period. In comparison, the fibrosis-resistant, Rowett black hooded rats had longer survival, milder proteinuria and reduced tubular damage as assessed by neutrophil gelatinase-associated lipocalin (NGAL) excretion, reduced loss of the slit diaphragm protein, nephrin, less glomerulosclerosis, tubulointerstitial fibrosis and matrix deposition assessed by periodic acid–Schiff, Picro-Sirius-red staining and fibronectin immunostaining. Less fibrosis was associated with reduced profibrotic transforming growth factor-beta, (TGF-β1) connective tissue growth factor (CTGF), and collagen type I alpha 1 (COL-1a1) mRNA levels. Milder inflammation demonstrated by histology was confirmed by less monocyte chemotactic protein 1 (MCP-1) mRNA. As a consequence of less inflammation, less oxidative and nitrative stress was obvious by less neutrophil cytosolic factor 1 (p47^phox) and NADPH oxidase-2 (p91^phox) mRNA. Reduced oxidative enzyme expression was accompanied by less lipid peroxidation as demonstrated by 4-hydroxynonenal (HNE) and less protein nitrosylation demonstrated by nitrotyrosine (NT) immunohistochemistry and quantified by Western blot. Our results demonstrate that mediators of fibrosis, inflammation and oxidative/nitrative stress were suppressed in doxorubicin nephropathy in fibrosis-resistant Rowett black hooded rats underlying the importance of these pathomechanisms in the progression of renal fibrosis initiated by glomerular podocyte damage.

Neuroprotective effects of mGluR II and III activators against staurosporine- and doxorubicin-induced cellular injury in SH-SY5Y cells: New evidence for a mechanism involving inhibition of AIF translocation

There are several experimental data sets demonstrating the neuroprotective effects of activation of group II and III metabotropic glutamate receptors (mGluR II/III), however, their effect on neuronal apoptotic processes has yet to be fully recognized. Thus, the comparison of the neuroprotective potency of the mGluR II agonist LY354740, mGluR III agonist ACPT-I, mGluR4 PAM VU0361737, mGluR8 PAM AZ12216052 and allosteric mGluR7 agonist AMN082 against staurosporine (St-) and doxorubicin (Dox)-induced cell death has been performed in undifferentiated (UN-) and retinoic acid differentiated (RA-) human neuroblastoma SH-SY5Y cells. The highest neuroprotection in UN-SH-SY5Y cells was noted for AZ12216052 (0.01-1 µM) and VU0361737 (1-10 µM), with both agents partially attenuating the St- and Dox-evoked cell death. LY354740 (0.01-10 µM) and ACPT-I (10 µM) were protective only against the St-evoked cell damage, whereas AMN082 (0.001-0.01 µM) attenuated only the Dox-induced cell death. In RA-SH-SY5Y, a moderate neuroprotective response of mGluR II/III activators was observed for LY354740 (10 µM) and AZ12216052 (0.01 and 10 µM), which afforded protection only against the St-induced cell damage. The protection mediated by mGluR II/III activators against the St- and Dox-evoked cell death in UN-SH-SY5Y cells was not related to attenuation of caspase-3 activity, however, a decrease in the number of TUNEL-positive nuclei was found. Moreover, mGluR II/III activators attenuated the cytosolic level of the apoptosis inducing factor (AIF), which was increased after St and Dox exposure. Our data point to differential neuroprotective efficacy of various mGluR II/III activators in attenuating St- and Dox-evoked cell damage in SH-SY5Y cells, and dependence of the effects on the cellular differentiation state, as well on the type of the pro-apoptotic agent that is employed. Moreover, the neuroprotection mediated by mGluR II/III activators is accompanied by inhibition of caspase-3-independent DNA fragmentation evoked by AIF translocation.

Urotensin II inhibits doxorubicin-induced human umbilical vein endothelial cell death by modulating ATF expression and via the ERK and Akt pathway

Background and Purpose

Regulation of the homeostasis of vascular endothelium is critical for the processes of vascular remodeling and angiogenesis under physiological and pathological conditions. Urotensin II (U-II), a potent vasoactive peptide, participates in vascular and myocardial remodeling after injury. We investigated the protective effect of U-II on doxorubicin (DOX)-induced apoptosis in cultured human umbilical vein endothelial cells (HUVECs) and the potential mechanisms involved in this process.

Experimental Approach

Cultured HUVECs were treated with vehicle, DOX (1 µM), U-II, or U-II plus DOX. Apoptosis was evaluated by DNA strand break level with TdT-mediated dUTP nick-end labeling (TUNEL) staining. Western blot analysis was employed to determine the related protein expression and flow cytometry assay was used to determine the TUNEL positive cells.

Key Results

U-II reduced the quantity of cleaved caspase-3 and cytosol cytochrome c and increased Bcl-2 expression, which results in protecting HUVECs from DOX-induced apoptosis. U-II induced Activating transcription factor 3 (ATF3) at both mRNA and protein levels in U-II-treated cells. Knockdown of ATF3 with ATF3 siRNA significantly reduced ATF3 protein levels and U-II protective effect under DOX-treated condition. U-II downregulated p53 expression in DOX-induced HUVECs apoptosis, and it rapidly activated extracellular signal-regulated protein kinase (ERK) and Akt. The DOX induced change of p53 was not affected by U-II antagonist (urantide) under ATF-3 knockdown. The inhibitory effect of U-II on DOX-increased apoptosis was attenuated by inhibitors of ERK (U0126) and PI3K/Akt (LY294002).

Conclusion and Implications

Our observations provide evidence that U-II protects HUVECs from DOX-induced apoptosis. ERK-Akt phosphorylation, ATF3 activation, and p53 downregulation may play a signal-transduction role in this process.

Acylated and unacylated ghrelin inhibit doxorubicin-induced apoptosis in skeletal muscle

AIM

Doxorubicin, a potent chemotherapeutic drug, has been demonstrated previously as an inducer of apoptosis in muscle cells. Extensive induction of apoptosis may cause excessive loss of muscle cells and subsequent functional decline in skeletal muscle. This study examined the effects of acylated ghrelin, a potential agent for treating cancer cachexia, on inhibiting apoptotic signalling in doxorubicin-treated skeletal muscle. Unacylated ghrelin, a form of ghrelin that does not bind to GHSR-1a, is also employed in this study to examine the GHSR-1a signalling dependency of the effects of ghrelin.

METHODS

Adult C57BL/6 mice were randomly assigned to saline control (CON), doxorubicin (DOX), doxorubicin with treatment of acylated ghrelin (DOX+Acylated Ghrelin) and doxorubicin with treatment of unacylated ghrelin (DOX+Unacylated Ghrelin). Mice in all groups that involved DOX were intraperitoneally injected with 15 mg of doxorubicin per kg body weight, whereas mice in CON group received saline as placebo. Gastrocnemius muscle tissues were harvested after the experimental period for analysis.

RESULTS

The elevation of apoptotic DNA fragmentation and number of TUNEL-positive nuclei were accompanied with the upregulation of Bax in muscle after exposure to doxorubicin, but all these changes were neither seen in the muscle treated with acylated ghrelin nor unacylated ghrelin after doxorubicin exposure. Protein abundances of autophagic markers including LC3 II-to-LC3 I ratio, Atg12-5 complex, Atg5 and Beclin-1 were not altered by doxorubicin but were upregulated by the treatment of either acylated or unacyated ghrelin. Histological analysis revealed that the amount of centronucleated myofibres was elevated in doxorubicin-treated muscle while muscle of others groups showed normal histology.

CONCLUSIONS

Collectively, our data demonstrated that acylated ghrelin administration suppresses the doxorubicin-induced activation of apoptosis and enhances the cellular signalling of autophagy. The treatment of unacylated ghrelin has similar effects as acylated ghrelin on apoptotic and autophagic signalling, suggesting that the effects of ghrelin are probably mediated through a signalling pathway that is independent of GHSR-1a. These findings were consistent with the hypothesis that acylated ghrelin inhibits doxorubicin-induced upregulation of apoptosis in skeletal muscle while treatment of unacylated ghrelin can achieve similar effects as the treatment of acylated ghrelin. The inhibition of apoptosis and enhancement of autophagy induced by acylated and unacylated ghrelin might exert myoprotective effects on doxorubicin-induced toxicity in skeletal muscle.