The JNK, ERK and p53 pathways play distinct roles in apoptosis mediated by the antitumor agents vinblastine, doxorubicin, and etoposide

Impact of Complex Apoptotic Signaling Pathways on Cancer Cell Sensitivity to Therapy

Anticancer drugs induce apoptotic and non-apoptotic cell death in various cancer types. The signaling pathways for anticancer drug-induced apoptotic cell death have been shown to differ between drug-sensitive and drug-resistant cells. In atypical multidrug-resistant leukemia cells, the c-Jun/activator protein 1 (AP-1)/p53 signaling pathway leading to apoptotic death is altered. Cancer cells treated with anticancer drugs undergo c-Jun/AP-1-mediated apoptotic death and are involved in c-Jun N-terminal kinase activation and growth arrest- and DNA damage-inducible gene 153 (Gadd153)/CCAAT/enhancer-binding protein homologous protein pathway induction, regardless of the p53 genotype. Gadd153 induction is associated with mitochondrial membrane permeabilization after anticancer drug treatment and involves a coupled endoplasmic reticulum stress response. The induction of apoptosis by anticancer drugs is mediated by the intrinsic pathway (cytochrome c, Cyt c) and subsequent activation of the caspase cascade via proapoptotic genes (e.g., Bax and Bcl-xS) and their interactions. Anticancer drug-induced apoptosis involves caspase-dependent and caspase-independent pathways and occurs via intrinsic and extrinsic pathways. The targeting of antiapoptotic genes such as Bcl-2 enhances anticancer drug efficacy. The modulation of apoptotic signaling by Bcl-xS transduction increases the sensitivity of multidrug resistance-related protein-overexpressing epidermoid carcinoma cells to anticancer drugs. The significance of autophagy in cancer therapy remains to be elucidated. In this review, we summarize current knowledge of cancer cell death-related signaling pathways and their alterations during anticancer drug treatment and discuss potential strategies to enhance treatment efficacy.

The Essential Oil from Conyza bonariensis (L.) Cronquist (Asteraceae) Exerts an In Vitro Antimelanoma Effect by Inducing Apoptosis and Modulating the MAPKs, NF-κB, and PKB/AKT Signaling Pathways

The characterization and cytotoxicity of the essential oil from Conyza bonariensis (L.) aerial parts (CBEO) were previously conducted. The major compound was (Z)-2-lachnophyllum ester (EZ), and CBEO exhibited significant ROS-dependent cytotoxicity in the melanoma cell line SK-MEL-28. Herein, we employed the Molegro Virtual Docker v.6.0.1 software to investigate the interactions between the EZ and Mitogen-Activated Protein Kinases (MAPKs), the Nuclear Factor kappa B (NF-κB), and the Protein Kinase B (PKB/AKT). Additionally, in vitro assays were performed in SK-MEL-28 cells to assess the effect of CBEO on the cell cycle, apoptosis, and these signaling pathways by flow cytometry and the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay using MAPKs inhibitors. CBEO induced a significant increase in the sub-G1 peak, as well as biochemical and morphological changes characteristic of apoptosis. The in-silico results indicated that EZ interacts with Extracellular Signal-Regulated Kinase 1 (ERK1), c-Jun N-terminal Kinase 1 (JNK1), p38α MAPK, NF-κB, and PKB/AKT. Moreover, CBEO modulated the ERK1/2, JNK, p38 MAPK, NF-κB, and PKB/AKT activities in SK-MEL-28 cells. Furthermore, CBEO's cytotoxicity against SK-MEL-28 cells was significantly altered in the presence of MAPKs inhibitors. These findings support the in vitro antimelanoma effect of CBEO through apoptosis induction, and the modulation of ERK, JNK, p38 MAPK, NF-κB, and PKB/AKT activities.

Novel Meta-iodobenzylguanidine and Etoposide Complex: Physicochemical Characterization and Mathematical Modeling of Anticancer Activity

It is hypothesized that meta-iodobenzylguanidine (MIBG) complexation with etoposide (VP-16) will improve drug solubility and specificity towards BE(2)C neuroblastoma (NB) cells, 90% of which are known to be MIBG avid. After MIBG and VP-16 interaction, the dry complex was analyzed for crystalline structure, surface morphology, solubility, and size distribution by X-ray powder diffraction (P-XRD), scanning electron microscopy (SEM), infrared (FTIR) and UV spectroscopy, and dynamic light scattering. After exposure to the complex, the cell viability and decay rates were assessed by the MTS assay and estimated using exponential decay models (EDM). Multi-factorial ANOVA and an independent t-test were used to assess for cell viability and solubility data, respectively. The resulting (1: 3 w/w) VP-16: MIBG complex had a mean diameter and zeta potential of 458.5 nm and 0.951 mV, respectively. It dramatically increased the drug apparent water solubility (~ 12-folds). This was ascribed to the formation of a VP-16/MIBG nanocrystalline state mainly governed by cation-π interactions, evidenced by FTIR, SEM, and P-XRD data following the complexation. The EDM relating percent cell viability to drug concentration yielded an excellent fit (r2 > 0.95) and enabled to estimate the IC50 values of both native drug and its complex: 6.2 μM and 5.23 μM, respectively (indicating a conservation of drug anticancer activity). The statistical results were consistent with those of the exponential decay models, indicating that MIBG does not inhibit the anticancer activity of VP-16. This study indicates that the VP-16/MIBG complexation improves VP-16 solubility without antagonizing its anticancer activity. Moreover, the efficiency of the EDM for drug IC50 estimation provides alternative mathematical method for such in vitro cytotoxicity studies.

Flavonoids from Hippophae rhamnoides Linn. Revert Doxorubicin-Induced Cardiotoxicity through Inhibition of Mitochondrial Dysfunction in H9c2 Cardiomyoblasts In Vitro

Doxorubicin (Dox) is one of the most frequently prescribed anti-cancer drugs. However, treatment with Dox is limited due to cumulative cardiotoxicity. 3-O-β-d-Sophorosylkaempferol-7-O-{3-O-[2(E)-2,6-dimethyl-6-hydroxyocta-2,7-dienoyl]}-α-L-rhamnoside (F-A), kaempferol 3-sophoroside 7-rhamnoside (F-B), and hippophanone (F-C) were successfully obtained by purification and separation of seabuckthorn seed residue in our previous research. This study was undertaken to investigate the protective effect of three flavonoids against Dox-induced H9c2 cell apoptosis. Cell proliferation was detected by MTT assay. 2',7'-Dichlorofluorescein diacetate (DCFH-DA) was used to determine the production of intracellular reactive oxygen species (ROS). ATP content was measured using an assay kit. Transmission electron microscopy (TEM) was used to observe changes in mitochondrial ultrastructure. The expression levels of proteins (p-JNK, JNK, p-Akt, Akt, p-P38, P38, p-ERK, ERK, p-Src, Src, Sab, IRE1α, Mfn1, Mfn2, and cleaved caspase-3) were evaluated by Western blot. Molecular docking was performed using AutoDock Vina. The three flavonoids could significantly relieve Dox-induced cardiac injury and inhibit cardiomyocyte apoptosis. The mechanisms were mainly related to the stability of mitochondrial structure and function maintained by suppressing the production of intracellular ROS, p-JNK and cleaved caspase-3, and increasing ATP contents and protein expression of mitochondrial mitofusin (Mfn1, Mfn2), Sab and p-Src. Pretreatment with flavonoids from Hippophae rhamnoides Linn. can reduce Dox-induced H9c2 cell apoptosis based on the 'JNK-Sab-Ros' signal pathway.

New Visions on Natural Products and Cancer Therapy: Autophagy and Related Regulatory Pathways

Macroautophagy (autophagy) has been a highly conserved process throughout evolution and allows cells to degrade aggregated/misfolded proteins, dysfunctional or superfluous organelles and damaged macromolecules, in order to recycle them for biosynthetic and/or energetic purposes to preserve cellular homeostasis and health. Changes in autophagy are indeed correlated with several pathological disorders such as neurodegenerative and cardiovascular diseases, infections, cancer and inflammatory diseases. Conversely, autophagy controls both apoptosis and the unfolded protein response (UPR) in the cells. Therefore, any changes in the autophagy pathway will affect both the UPR and apoptosis. Recent evidence has shown that several natural products can modulate (induce or inhibit) the autophagy pathway. Natural products may target different regulatory components of the autophagy pathway, including specific kinases or phosphatases. In this review, we evaluated ~100 natural compounds and plant species and their impact on different types of cancers via the autophagy pathway. We also discuss the impact of these compounds on the UPR and apoptosis via the autophagy pathway. A multitude of preclinical findings have shown the function of botanicals in regulating cell autophagy and its potential impact on cancer therapy; however, the number of related clinical trials to date remains low. In this regard, further pre-clinical and clinical studies are warranted to better clarify the utility of natural compounds and their modulatory effects on autophagy, as fine-tuning of autophagy could be translated into therapeutic applications for several cancers.

The effect of HIF-1α inhibition in breast cancer cells prior to doxorubicin treatment under conditions of normoxia and hypoxia

BACKGROUND

Oxygen deprivation is a key hallmark within solid tumours that contributes to breast-tumour pathophysiology. Under these conditions, neoplastic cells activate several genes, regulated by the HIF-1 transcription factor, which alters the tumour microenvironment to promote survival - including resistance to cell death in therapeutic attempts such as doxorubicin (Dox) treatment.

METHODS

We investigated HIF-1ɑ as a therapeutic target to sensitize breast cancer cells to Dox treatment. Under both normoxic (21% O₂) and hypoxic (∼0.1% O₂) conditions, the HIF-1 inhibitor, 2-methoxyestradiol (2-ME), was investigated as an adjuvant for its ability to alter MCF-7 cell viability, apoptosis, autophagy and molecular pathways which are often associated with increased cell survival.

RESULTS

Here we observed that an inverse relationship between HIF-1ɑ and apoptosis exists and that Dox promotes autophagy under hypoxic conditions. Although adjuvant therapy with 2-ME induced an antagonistic effect in breast cancer cells, upregulated HIF-1ɑ expression in a hypoxic environment promotes treatment resistance and this was attenuated once HIF-1ɑ gene expression was silenced.

CONCLUSION

Therefore, highlighting the identification of possible hypoxia-targeting therapies for breast cancer patients can be beneficial by promoting more favourable treatment responses.

Neuroprotective Potential of Berberine Against Doxorubicin-Induced Toxicity in Rat's Brain

Chemotherapy-associated neurotoxicity is one of the principal side-effects for doxorubicin (DOX)-treated cancer patients. Despite its poor-penetration across the blood-brain barrier (BBB), DOX is linked to the induction of oxidative stress and neuroinflammation. Berberine (BEB) is a natural polyphenolic alkaloid, which exhibits unique antioxidant activity and anti-inflammatory potential. The present study was performed to investigate the neuroprotective potential of BEB in a rodent model of DOX-induced neurotoxicity. Neurotoxicity was induced in rats via a single acute dose of DOX (20 mg/kg/week, i.p.). BEB was administered at 50 mg/kg/day orally for 10 days before and 4 days after DOX administration. Brain acetylcholinesterase (AChE) activities were evaluated. Oxidative stress was investigated via the colorimetric determination of lipid peroxides, glutathione reduced (GSH) contents and catalase (CAT) activities in the brain tissue. In addition, DOX-induced genotoxicity was evaluated using comet assay. DOX produced a significant elevation in AChE activities. Additionally, DOX provoked oxidative stress as evidenced from the significant elevation in lipid peroxidation along with depletion in GSH contents and CAT activities. Moreover, DOX resulted in neuroinflammation as indicated by the elevation of pro-inflammatory mediator glial fibrillary acid protein (GFAP), as well as, the pro-apoptotic nuclear factor kappa B (NF-κB) and caspase-3 in brain tissue. Co-treatment with BEB significantly counteracted DOX-induced oxidative stress, neuroinflammation and genotoxicity. Histopathological and immunohistochemical examination supported the biochemical results. BEB demonstrated neuroprotective potential through exerting cholinergic, anti-oxidative, genoprotective, anti-inflammatory, and anti-apoptotic activities. Our findings present BEB as a promising "pre-clinical" neuroprotective agent against DOX-induced neurotoxicity during anti-neoplastic therapy.

Protective Effect of Two Alkaloids from Hippophae rhamnoides Linn. against Doxorubicin-Induced Toxicity in H9c2 Cardiomyoblasts

BACKGROUND

Doxorubicin (Dox) is one of the most frequently prescribed anti-cancer drugs. However, clinical application with Dox is limited due to its potentially fatal cumulative cardiotoxicity. N-p-coumaroyl-4-aminobutan-1-ol (alk-A), an organic amide alkaloid and hippophamide (alk-B), a rare pyridoindole alkaloid were successfully obtained by purification and separation of seabuckthorn seed residue in our previous research. This study was undertaken to investigate the protective effect of alk-A and alk-B against Dox-induced embryonic rat cardiac cells (H9c2 cells) apoptosis.

METHODS

H9c2 cells were treated with Dox (2.5 µM) in the presence of alk-A and alk-B (10, 20, and 40 µM) and incubated for 24 h.

RESULTS

It was shown that pretreatment of the H9c2 cells with alk-A and alk-B significantly reduced Dox-induced apoptosis. Alk-A and alk-B both inhibited reactive oxygen species (ROS) production and suppressed cleaved-caspase-3 protein expression and the activation of JNK (Jun N-terminal kinases), as well as increasing ATP levels, favoring mitochondrial mitofusin protein expression, and relieving damage to mitochondrial DNA.

CONCLUSIONS

These results suggest that alk-A and alk-B can inhibit Dox-induced apoptosis in H9C2 cardiac muscle cells via inhibition of cell apoptosis and improvement of mitochondrial function, while alk-B showed more protection. Alk-B could be a potential candidate agent for protecting against cardiotoxicity in Dox-exposed patients.

Mesoporous silica coated carbon nanofibers reduce embryotoxicity via ERK and JNK pathways

Carbon nanofibers (CNFs) have been implicated in biomedical applications, yet, they are still considered as a potential hazard. Conversely, mesoporous silica is a biocompatible compound that has been used in various biomedical applications. In this regard, we recently reported that CNFs induce significant toxicity on the early stage of embryogenesis in addition to the inhibition of its angiogenesis. Thus, we herein use mesoporous silica coating of CNFs (MCNFs) in order to explore their outcome on normal development and angiogenesis using avian embryos at 3 days and its chorioallantoic membrane (CAM) at 6 days of incubation. Our data show that mesoporous silica coating of CNFs significantly reduces embryotoxicity provoked by CNFs. However, MCNFs exhibit slight increase in angiogenesis inhibition in comparison with CNFs. Further investigation revealed that MCNFs slightly deregulate the expression patterns of key controller genes involved in cell proliferation, survival, angiogenesis, and apoptosis as compared to CNFs. We confirmed these data using avian primary normal embryonic fibroblast cells established in our lab. Regarding the molecular pathways, we found that MCNFs downregulate the expression of ERK1/ERK2, p-ERK1/ERK2 and JNK1/JNK2/JNK3, thus indicating a protective role of MCNFs via ERK and JNK pathways. Our data suggest that coating CNFs with a layer of mesoporous silica can overcome their toxicity making them suitable for use in biomedical applications. Nevertheless, further investigations are required to evaluate the effects of MCNFs and their mechanisms using different in vitro and in vivo models.

PIAS2-mediated blockade of IFN-β signaling: a basis for sporadic Parkinson disease dementia

Familial Parkinson disease (PD) is associated with rare genetic mutations, but the etiology in most patients with sporadic (s)PD is largely unknown, and the basis for its progression to dementia (sPDD) is poorly characterized. We have identified that loss of IFNβ or IFNAR1, the receptor for IFNα/β, causes pathological and behavioral changes resembling PDD, prompting us to hypothesize that dysregulated genes in IFNβ-IFNAR signaling pathway predispose one to sPD. By transcriptomic analysis, we found defective neuronal IFNβ-IFNAR signaling, including particularly elevated PIAS2 associated with sPDD. With meta-analysis of GWASs, we identified sequence variants in IFNβ-IFNAR-related genes in sPD patients. Furthermore, sPDD patients expressed higher levels of PIAS2 mRNA and protein in neurons. To determine its function in brain, we overexpressed PIAS2 under a neuronal promoter, alone or with human α-synuclein, in the brains of mice, which caused motor and cognitive impairments and correlated with intraneuronal phosphorylated (p)α-synuclein accumulation and dopaminergic neuron loss. Ectopic expression of neuronal PIAS2 blocked mitophagy, increased the accumulation of senescent mitochondrial and oxidative stress, as evidenced by excessive oxDJ1 and 8OHdG, by inactivating ERK1/2-P53 signaling. Conversely, PIAS2 knockdown rescued the clinicopathological manifestations of PDD in Ifnb^-/- mice on restoring mitochondrial homeostasis, oxidative stress, and pERK1/2-pP53 signaling. The regulation of JAK-STAT2-PIAS2 signaling was crucial for neurite outgrowth and neuronal survival and excitability and thus might prevent cognitive impairments. Our findings provide insights into the progression of sPD and dementia and have implications for new therapeutic approaches.

Animal models of chemotherapy-induced cognitive decline in preclinical drug development

RATIONALE

Chemotherapy-induced cognitive impairment (CICI), chemobrain, and chemofog are the common terms for mental dysfunction in a cancer patient/survivor under the influence of chemotherapeutics. CICI is manifested as short/long term memory problems and delayed mental processing, which interferes with a person's day-to-day activities. Understanding CICI mechanisms help in developing therapeutic interventions that may alleviate the disease condition. Animal models facilitate critical evaluation to elucidate the underlying mechanisms and form an integral part of verifying different treatment hypotheses and strategies.

OBJECTIVES

A methodical evaluation of scientific literature is required to understand cognitive changes associated with the use of chemotherapeutic agents in different preclinical studies. This review mainly emphasizes animal models developed with various chemotherapeutic agents individually and in combination, with their proposed mechanisms contributing to the cognitive dysfunction. This review also points toward the analysis of chemobrain in healthy animals to understand the mechanism of interventions in absence of tumor and in tumor-bearing animals to mimic human cancer conditions to screen potential drug candidates against chemobrain.

RESULTS

Substantial memory deficit as a result of commonly used chemotherapeutic agents was evidenced in healthy and tumor-bearing animals. Spatial and episodic cognitive impairments, alterations in neurotrophins, oxidative and inflammatory markers, and changes in long-term potentiation were commonly observed changes in different animal models irrespective of the chemotherapeutic agent.

CONCLUSION

Dyscognition exists as one of the serious side effects of cancer chemotherapy. Due to differing mechanisms of chemotherapeutic agents with differing tendencies to alter behavioral and biochemical parameters, chemotherapy may present a significant risk in resulting memory impairments in healthy as well as tumor-bearing animals.

Challenges and potential for improving the druggability of podophyllotoxin-derived drugs in cancer chemotherapy

Covering: up to 2020As a main bioactive component of the Chinese, Indian, and American Podophyllum species, the herbal medicine, podophyllotoxin (PTOX) exhibits broad spectrum pharmacological activity, such as superior antitumor activity and against multiple viruses. PTOX derivatives (PTOXs) could arrest the cell cycle, block the transitorily generated DNA/RNA breaks, and blunt the growth-stimulation by targeting topoisomerase II, tubulin, or insulin-like growth factor 1 receptor. Since 1983, etoposide (VP-16) is being used in frontline cancer therapy against various cancer types, such as small cell lung cancer and testicular cancer. Surprisingly, VP-16 (ClinicalTrials NTC04356690) was also redeveloped to treat the cytokine storm in coronavirus disease 2019 (COVID-19) in phase II in April 2020. The treatment aims at dampening the cytokine storm and is based on etoposide in the case of central nervous system. However, the initial version of PTOX was far from perfect. Almost all podophyllotoxin derivatives, including the FDA-approved drugs VP-16 and teniposide, were seriously limited in clinical therapy due to systemic toxicity, drug resistance, and low bioavailability. To meet this challenge, scientists have devoted continuous efforts to discover new candidate drugs and have developed drug strategies. This review focuses on the current clinical treatment of PTOXs and the prospective analysis for improving druggability in the rational design of new generation PTOX-derived drugs.

A Prospective, Randomized, Placebo-Controlled Study of a Combination of Simvastatin and Chemotherapy in Metastatic Breast Cancer

Preclinical studies support the anticancer activity of statins; however, the existing clinical evidence is inconsistent and not definitive. Our study aimed at evaluating a postulated cancer chemo-sensitizing effect of statin (simvastatin) in a cohort of metastatic breast cancer (MBC) patients. We designed a prospective, single-centered, randomized, double blinded, placebo-controlled trial that encompassed MBC patients with an ECOG Performance Status Scale ≤2 and scheduled to be treated with a chemotherapy regimen consisting of carboplatin and vinorelbine every 3 weeks at Al-Baironi Hospital, Damascus, Syria. Patients were enrolled between August 2011 and July 2012 and randomly allocated to receive a 15-day course of either simvastatin (40 mg) or placebo seven days prior to the first day of each chemotherapy cycle and then continued for eight days in each individual cycle. Primary endpoints were objective response rate (ORR) and toxicity, and the secondary endpoint was overall survival (OS). Eighty-two patients met the inclusion criteria and consented. ORR (35% vs. 32.5%) and predominant toxicity and grade ≥3 neutropenia (occurred in 30% vs. 40% of the patients) were not significantly different between simvastatin and placebo groups, respectively. Over a median follow-up of 44 months (range, 10-60), median OS was 15 months in the simvastatin group and 17 the in placebo group (hazard ratio (HR) = 1.16, 95% CI (0.70-1.91), P=0.57). Elevated baseline values of high-sensitivity C-reactive protein (hsCRP >10 mg/l), lactate dehydrogenase (LDH >480 U/L), and chemotherapy being ≥2^nd line were significantly associated with shorter OS for the total cohort in both Univariate and multivariate analyses. Our data prove a safe profile of simvastatin at 40 mg per day combined with carboplatin and vinorelbine in MBC patients but without any beneficial increase of tumor sensitivity to chemotherapy. Moreover, we demonstrated a strong clinical advantage of baseline values of hsCRP and LDH as useful prognostic tools in MBC patients. This trial is registered with ISRCTN12964275.

Mebendazole is unique among tubulin-active drugs in activating the MEK-ERK pathway

We recently showed that the anti-helminthic compound mebendazole (MBZ) has immunomodulating activity in monocyte/macrophage models and induces ERK signalling. In the present study we investigated whether MBZ induced ERK activation is shared by other tubulin binding agents (TBAs) and if it is observable also in other human cell types. Curated gene signatures for a panel of TBAs in the LINCS Connectivity Map (CMap) database showed a unique strong negative correlation of MBZ with MEK/ERK inhibitors indicating ERK activation also in non-haematological cell lines. L1000 gene expression signatures for MBZ treated THP-1 monocytes also connected negatively to MEK inhibitors. MEK/ERK phosphoprotein activity testing of a number of TBAs showed that only MBZ increased the activity in both THP-1 monocytes and PMA differentiated macrophages. Distal effects on ERK phosphorylation of the substrate P90RSK and release of IL1B followed the same pattern. The effect of MBZ on MEK/ERK phosphorylation was inhibited by RAF/MEK/ERK inhibitors in THP-1 models, CD3/IL2 stimulated PBMCs and a MAPK reporter HEK-293 cell line. MBZ was also shown to increase ERK activity in CD4+ T-cells from lupus patients with known defective ERK signalling. Given these mechanistic features MBZ is suggested suitable for treatment of diseases characterized by defective ERK signalling, notably difficult to treat autoimmune diseases.

Sodium thiosulfate prevents doxorubicin-induced DNA damage and apoptosis in cardiomyocytes in mice

AIM

Doxorubicin (DOX) induces dose-dependent cardiotoxicity due to reactive oxygen species (ROS)-mediated oxidative stress and subsequent apoptosis of cardiomyocytes. We aimed to assess whether sodium thiosulfate (STS), which has antioxidant and antiapoptotic properties, exerts cardioprotective effects on DOX-induced cardiomyopathy.

MAIN METHODS

Male C57BL/6N mice were divided into four groups, control, DOX, STS, and DOX + STS, and administered DOX (20 or 30 mg/kg) or normal saline intraperitoneally, followed by an injection of STS (2 g/kg) or normal saline 4 h later.

KEY FINDINGS

The DOX group showed a poorer 6-day survival and decreased cardiac function than the DOX + STS group. The DOX group showed a marked increase in the plasma creatine kinase isoenzyme myocardial band (CK-MB) and lactate dehydrogenase (LDH) levels 10 h after DOX injection, while the DOX + STS group showed suppression of DOX-induced elevation of CK-MB and LDH levels. The DOX group showed increased 8-hydroxy-2'-deoxyguanosine (8-OHdG) levels in the heart, whereas the DOX + STS group showed increased catalase and superoxide dismutase (SOD) activities and decreased 8-OHdG levels in the heart compared with DOX group, suggesting that STS reduces DOX-induced DNA damage by improving antioxidant enzymes activities in cardiomyocytes. Additionally, the DOX + STS group showed attenuation of cleaved caspase-3 and DNA fragmentation in cardiomyocytes compared with the DOX group, suggesting that STS suppresses DOX-induced apoptosis in cardiomyocytes.

SIGNIFICANCE

STS exerts cardioprotective effects against DOX-induced cardiac dysfunction partly by improving antioxidant defense and suppressing apoptosis, indicating the therapeutic potential of STS against DOX-induced cardiomyopathy.

The natural alkaloid Jerantinine B has activity in acute myeloid leukemia cells through a mechanism involving c-Jun

BACKGROUND

Acute myeloid leukemia (AML) is a heterogenous hematological malignancy with poor long-term survival. New drugs which improve the outcome of AML patients are urgently required. In this work, the activity and mechanism of action of the cytotoxic indole alkaloid Jerantinine B (JB), was examined in AML cells.

METHODS

We used a combination of proliferation and apoptosis assays to assess the effect of JB on AML cell lines and patient samples, with BH3 profiling being performed to identify early effects of the drug (4 h). Phosphokinase arrays were adopted to identify potential driver proteins in the cellular response to JB, the results of which were confirmed and extended using western blotting and inhibitor assays and measuring levels of reactive oxygen species.

RESULTS

AML cell growth was significantly impaired following JB exposure in a dose-dependent manner; potent colony inhibition of primary patient cells was also observed. An apoptotic mode of death was demonstrated using Annexin V and upregulation of apoptotic biomarkers (active caspase 3 and cleaved PARP). Using BH3 profiling, JB was shown to prime cells to apoptosis at an early time point (4 h) and phospho-kinase arrays demonstrated this to be associated with a strong upregulation and activation of both total and phosphorylated c-Jun (S63). The mechanism of c-Jun activation was probed and significant induction of reactive oxygen species (ROS) was demonstrated which resulted in an increase in the DNA damage response marker γH2AX. This was further verified by the loss of JB-induced C-Jun activation and maintenance of cell viability when using the ROS scavenger N-acetyl-L-cysteine (NAC).

CONCLUSIONS

This work provides the first evidence of cytotoxicity of JB against AML cells and identifies ROS-induced c-Jun activation as the major mechanism of action.

Doxorubicin chemotherapy-induced "chemo-brain": Meta-analysis

Doxorubicin is a leading chemotherapeutic halting cellular replication and inducing p53-dependent apoptosis in cancerous tissue. Like many chemotherapies, doxorubicin damages healthy tissue throughout the body through cellular mechanisms independent of its chemotherapeutic action. Although cognitive impairment is commonly recorded in patients after chemotherapy, the occurrence of doxorubicin-induced "chemo-brain" is debated, as doxorubicin cannot cross the blood-brain barrier. However, the potential of indirect doxorubicin neurotoxicity remains, providing a foundation for doxorubicin-mediated chemo-brain. We present the first meta-analysis of defined cognitive performance of doxorubicin-treated patients. A search of PubMed and MedLine collected 494 studies, 14 of which met analysis criteria. Performance of 511 doxorubicin-treated women with breast cancer was compared to that of 306 healthy controls across measures of defined cognitive modalities. Treated patients experience significant impairment in global cognition compared to controls (g₌ -0.41, P < 0.001), with select impairment in executive function (g = -0.25, P < 0.0001), language (g = -0.30, P < 0.0001), memory (g = -0.12, P < 0.01) and processing speed (g = -0.28, P < 0.01). Within memory, short-term verbal memory is most significantly affected (g = -0.21, P < 0.01). Impairment in select cognitive modalities (executive function, language, memory, short-term verbal memory, processing speed) is prevalent in doxorubicin-treated patients, with some cognitive functions remaining intact (attention, motor function, visuospatial abilities). This information can guide the development of future interventions to improve quality-of-life (QOL) and doxorubicin-derived therapies that target cytotoxicity to cancerous tissue, avoiding healthy tissue damage, which is mediated by seemingly independent mechanisms.

Synthesis, biological evaluation and molecular docking studies of new amides of 4-chlorothiocolchicine as anticancer agents

Colchicine belongs to a large group of microtubule polymerization inhibitors. Although the anti-cancer activity of colchicine and its derivatives has been established, none of them has found commercial application in cancer treatment due to side effects. Therefore, we designed and synthesized a series of six triple-modified 4-chlorothiocolchicine analogues with amide moieties and one urea derivative. These novel derivatives were tested against several different cancer cell lines (A549, MCF-7, LoVo, LoVo/DX) and primary acute lymphoblastic leukemia (ALL) cells and they showed activity in the nanomolar range. The obtained IC₅₀ values for novel derivatives were lower than those obtained for unmodified colchicine and common anticancer drugs such as doxorubicin and cisplatin. Further studies of colchicine and selected analogues were undertaken to indicate that they induced apoptotic cell death in ALL-5 cells. We also performed in silico studies to predict binding modes of the 4-chlorothiocolchicine derivatives to different β tubulin isotypes. The results indicate that select triple-modified 4-chlorothiocolchicine derivatives represent highly promising novel cancer chemotherapeutics.

Synthesis, biological evaluation and molecular docking studies of new amides of 4-bromothiocolchicine as anticancer agents

Colchicine is the major alkaloid isolated from the plant Colchicum autumnale, which shows strong therapeutic effects towards different types of cancer. However, due to the toxicity of colchicine towards normal cells its application is limited. To address this issue we synthesized a series of seven triple-modified 4-bromothiocolchicine analogues with amide moieties. These novel derivatives were active in the nanomolar range against several different cancer cell lines and primary acute lymphoblastic leukemia cells, specifically compounds: 5-9 against primary ALL-5 (IC₅₀ = 5.3-14 nM), 5, 7-9 against A549 (IC₅₀ = 10 nM), 5, 7-9 against MCF-7 (IC₅₀ = 11 nM), 5-9 against LoVo (IC₅₀ = 7-12 nM), and 5, 7-9 against LoVo/DX (IC₅₀ = 48-87 nM). These IC₅₀ values were lower than those obtained for unmodified colchicine and common anticancer drugs such as doxorubicin and cisplatin. Further studies revealed that colchicine and selected analogues induced characteristics of apoptotic cell death but manifested their effects in different phases of the cell cycle in MCF-7 versus ALL-5 cells. Specifically, while colchicine and the studied derivatives arrested MCF-7 cells in mitosis, very little mitotically arrested ALL-5 cells were observed, suggesting effects were manifest instead in interphase. We also developed an in silico model of the mode of binding of these compounds to their primary target, β-tubulin. We conducted a correlation analysis (linear regression) between the calculated binding energies of colchicine derivatives and their anti-proliferative activity, and determined that the obtained correlation coefficients strongly depend on the type of cells used.

Transmembrane TNF-alpha promotes chemoresistance in breast cancer cells

Chemoresistance remains a major obstacle to successful treatment of breast cancer. Although soluble tumor necrosis factor-α (sTNF-α) has been implicated in mediating drug-resistance in human cancers, whether transmembrane tumor necrosis factor-α (tmTNF-α) plays a role in chemoresistance remains unclear. Here we found that over 50% of studied patients expressed tmTNF-α at high levels in breast cancer tissues and tmTNF-α expression positively correlated with resistance to anthracycline chemotherapy. Alteration of tmTNF-α expression changed the sensitivity of primary human breast cancer cells and breast cancer cell lines to doxorubicin (DOX). Overexpression of N-terminal fragment (NTF) of tmTNF-α, a mutant form with intact intracellular domain of tmTNF-α to transmit reverse signals, induced DOX-resistance. Mechanistically, the tmTNF-α/NTF-ERK-GST-π axis and tmTNF-α/NTF-NF-κB-mediated anti-apoptotic functions were required for tmTNF-α-induced DOX-resistance. In a xenograft mouse model, the combination of tmTNF-α suppression with chemotherapy significantly enhanced the efficacy of DOX. Our data indicate that tmTNF-α mediates DOX-resistance through reverse signaling and targeting tmTNF-α may be beneficial for the treatment of DOX-resistant breast cancer.

Effect of statins on breast cancer recurrence and mortality: a review

Statins, or 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors, are medications that have been used for decades to lower cholesterol and to prevent or treat cardiovascular diseases. Since their approval by the US Food and Drug Administration in the 1980s, other potential uses for statins have been speculated on and explored. Basic science and clinical research suggest that statins are also effective in the management of breast cancer. Specifically, in various breast cancer cell lines, statins increase apoptosis and radiosensitivity, inhibit proliferation and invasion, and decrease the metastatic dissemination of tumors. Clinical trials in breast cancer patients support these laboratory findings by demonstrating improved local control and a mortality benefit for statin users. A role for statins in the management of aggressive breast cancers with poor outcomes – namely, inflammatory breast cancer and triple-negative breast cancer – is particularly implicated. However, data exist showing that statins may actually promote invasive breast disease after long-term use and thus should be prescribed cautiously. Furthermore, a general consensus on the type of statin that should be administered, for how long, and when in relation to time of diagnosis is lacking. Given their low toxicity profile, affordability, and ease of use, consideration of statins as a therapy for breast cancer patients is imminent. In this review, we summarize current evidence regarding statins and clinical breast cancer outcomes, as well as discuss potential future studies that could shed light on this increasingly relevant topic.

Ginkgo biloba exocarp extracts induces apoptosis in Lewis lung cancer cells involving MAPK signaling pathways

ETHNOPHARMACOLOGICAL RELEVANCE

A fruit of Ginkgo biloba L. is known as Ginkgo nuts. It is an edible traditional Chinese medicine, and could be used for the treatment of cancer thousands of years ago in China. The extracts prepared from the exocarp of Ginkgo biloba (Ginkgo biloba exocarp extracts, GBEE) has the effects of anti-cancer, immune promotion, anti-aging and etc.

AIM OF STUDY

To study the effects of GBEE inducing apoptosis in Lewis lung cancer (LLC) cells and the role of Mitogen-activated protein kinase(MAPK) signaling pathways in it.

MATERIALS AND METHODS

The LLC solid tumor model was established in C57BL/6J mice. The tumor-bearing mice were randomly divided into 5 groups. A normal control group without tumor cells was established additionally. There were 10 mice in each group, and they were dosed 24h after inoculation. The GBEE (50, 100, 200mg/kg b.w.) groups were dosed by intragastric gavage (i.g.). The mice in positive control group were intraperitoneal (i.p.) injected with cyclophosphamide (CPA) at a dose of 20mg/kg (b.w.). The model control group and the normal control group were both given normal saline (NS) by i.g.. All the groups were dosed at a volume of 0.1mL/10g (b.w.), once a day for 18d. The day after the last administration, the transplanted tumors was stripped and weighed, and the inhibition rate was calculated. In vitro experiments, MTT method was applied to detect the effects of GBEE on LLC cells and primary cultured mouse lung cells. Annexin V-FITC/PI method was used to detect the apoptosis rate of LLC cells. Rhodamine 123 method was used to detect the Mitochondrial transmembrane potential (MTP). Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) was used to detect the levels of Fas mRNA. Western Blot was used to detect the expression of Bax, Bcl-2, Cyt C, cleaved Caspase-3 and MAPK proteins in the corresponding parts of LLC cells.

RESULTS

GBEE (50-200mg/kg) inhibited the growth of LLC transplanted tumors with a dose-effect relationship. GBEE (5-160µg/mL) inhibited the proliferation of LLC cells in vitro with the half maximal inhibitory concentration (IC50) value of 162.43µg/mL, while it had no significant inhibitory effects on the primary cultured mouse lung cells. After GBEE (10, 20 and 40µg/mL) acted on the LLC cells, the apoptosis rate was increased and the MTP was decreased. The ratio of Bax/Bcl-2 was increased in the cells. Meanwhile, it also promoted the translocation of Bax/Bcl-2 in mitochondrial membrane and the release of Cyt C from mitochondria to cytosol. In addition, it up-regulated the cleaved-Caspase-3 protein expression. The mRNA levels of Fas and the protein levels of Fas, FasL and p-p38 in the cells were both increased. The levels of p-ERK1/2 and p-JNK1/2 protein were down-regulated but the p38, ERK1/2 and JNK1/2 were not significantly changed.

CONCLUSIONS

GBEE induces apoptosis in LLC cells via mitochondrial-mediated intrinsic pathway and death receptor-mediated extrinsic pathway, which may be closely relevant to the regulation of MAPK signaling pathways.

Uncaria tomentosa (Willd. ex Schult.) DC (Rubiaceae) Sensitizes THP-1 Cells to Radiation-induced Cell Death

Background:

Uncaria tomentosa (Willd. ex Schult.) DC (Rubiaceae), known as Cat's Claw or Uña de gato, is a traditionally used medicinal plant native to Peru. Some studies have shown that U. tomentosa can act as an antiapoptotic agent and enhance DNA repair in chemotherapy-treated cells although others have shown that U. tomentosa enhanced apoptosis.

Objective:

To determine if treatment with U. tomentosa can significantly enhance cell death in THP-1 cells exposed to ionizing radiation.

Materials and Methods:

THP-1 monocyte-like cells were treated with ethanolic extracts of U. tomentosa in the presence or absence of bacterial lipopolysaccharide and then exposed to ionizing radiation. Cell proliferation was assessed by MTT and clonogenic assays and the effects on cell cycle measured by flow cytometry and immunoblotting. Changes in cell signaling were determined by immunoblotting and cytokine ELISA and activation of apoptosis measured by caspase activation and DNA fragmentation analysis.

Results:

Treatment of THP-1 cells with U. tomentosa had a small effect on cell proliferation. However, when the U. tomentosa-pretreated cells were also subjected to 5–9 Gy ionizing radiation, they showed a significant decrease in cell proliferation and increased cellular apoptosis as measured by DNA fragmentation and caspase activation. Treatment with U. tomentosa also decreased the expression of Cyclin E and Cyclin B, key regulators of normal cell cycle progression, and decreased the phosphorylation of various stress-activated, cell survival proteins including p38, ERK, and SAP/JNK kinase.

Conclusions:

These results suggest that U. tomentosa could be useful in enhancing cell death following anticancer therapies including ionizing radiation.

SUMMARY

Treatment of THP-1 cells with Uncaria tomentosa increases their susceptibility to X-rays. The combination of Uncaria tomentosa and X-ray exposure strongly inhibits cell signaling and promotes apoptosis.

Abbreviations Used: LPS: Lipopolysaccharide, TNF: Tumor necrosis factor: IL-1, Interleukin-1: SDS: Sodium dodecylsulphate, TBS: Tris-buffered saline.

Microtubule destabilising agents: far more than just antimitotic anticancer drugs

Vinca alkaloids have been approved as anticancer drugs for more than 50 years. They have been classified as cytotoxic chemotherapy drugs that act during cellular mitosis, enabling them to target fast growing cancer cells. With the evolution of cancer drug development there has been a shift towards new "targeted" therapies to avoid the side effects and general toxicities of "cytotoxic chemotherapies" such as the vinca alkaloids. Due to their original classification, many have overlooked the fact that vinca alkaloids, taxanes and related drugs do have a specific molecular target: tubulin. They continue to be some of the most effective anticancer drugs, perhaps because their actions upon the microtubule network extend far beyond the ability to halt cells in mitosis, and include the induction of apoptosis at all phases of the cell cycle. In this review, we highlight the numerous cellular consequences of disrupting microtubule dynamics, expanding the textbook knowledge of microtubule destabilising agents and providing novel opportunities for their use in cancer therapy.

Etoposide induces pancreatic β-cells cytotoxicity via the JNK/ERK/GSK-3 signaling-mediated mitochondria-dependent apoptosis pathway

Etoposide is widely used in the treatment of the different types of tumors such as pancreatic cancer. However, etoposide also causes several unwanted side-effects in normal viable cells, including pancreatic β-cells, which are vulnerable to chemical-induced injuries, and the molecular mechanisms underlying etoposide-induced apoptosis are still unclear. Here, the results showed that in RIN-m5F cells (a β-cell-derived cell line), the number of viable cells was significantly decreased after 24h of etoposide treatment and underwent mitochondria-dependent apoptotic signals accompanied by mitochondrial dysfunction, and increases in the population of sub-G1 hypodiploid cells and apoptotic cells, caspase-3 activity, and the activation of caspase cascades. Etoposide also increased the phosphorylation levels of glycogen synthase kinase (GSK)-3α/β in treated RIN-m5F cells. Pretreatment with LiCl, a GSK-3 inhibitor, prevented etoposide-induced mitochondria-dependent apoptosis and GSK-3 protein phosphorylation in RIN-m5F cells. Furthermore, exposure of the cells to etoposide induced the phosphorylation of c-Jun N-terminal kinase (JNK) and extracellular signal-related kinase (ERK)1/2 but not p38-MAPK, which was suppressed by the specific JNK inhibitor (SP600125) and ERK1/2 inhibitor (PD98059), respectively. Additionally, pretreatment with both SP600125 and PD98059 effectively suppressed etoposide-induced β-cell cytotoxicity, apoptosis, and GSK-3 protein phosphorylation; however, LiCl did not reverse JNK and ERK1/2 phosphorylation. Taken together, these results suggest that etoposide is capable of causing cytotoxicity on pancreatic β-cells by inducing apoptosis through the JNK/ERK-mediated GSK-3 downstream-triggered mitochondria-dependent signaling pathway.

Structural Determinants of p53-Independence in Anticancer Ruthenium-Arene Schiff-Base Complexes

p53 is a key tumor suppressor gene involved in key cellular processes and implicated in cancer therapy. However, it is inactivated in more than 50% of all cancers due to mutation or overexpression of its negative regulators. This leads to drug resistance and poor chemotherapeutic outcome as most clinical drugs act via a p53-dependent mechanism of action. An attractive strategy to circumvent this resistance would be to identify new anticancer drugs that act via p53-independent mode of action. In the present study, we identified 9 Ru (II)-Arene Schiff-base (RAS) complexes able to induce p53-independent cytotoxicity and discuss structural features that are required for their p53-independent activity. Increasing hydrophobicity led to an increase in cellular accumulation in cells with a corresponding increase in efficacy. We further showed that all nine complexes demonstrated p53-independent activity. This was despite significant differences in their physicochemical properties, suggesting that the iminoquinoline ligand, a common structural feature for all the complexes, is required for the p53-independent activity.

Synthesis of CaCO3 Nanobelts for Drug Delivery in Cancer Therapy

Nanobelt carriers have demonstrated some advantages such as good biocompatibility, biodegradability, and strain-accommodating properties. We prepared an optimized nanobelt carrier formulation for drug (etoposide) as an oral delivery system and estimated the potential of calcium carbonate (CaCO3) nanobelts. The nanobelts were prepared by the method of binary solvent approach and were characterized by transmission electron microscope (TEM), scanning electron microscopy (SEM), and ultraviolet-visible (UV-vis) spectra. MTT (3-(4,5-dimethyl-2-thiazolyl)-2, 5-diphenyl-2H-tetrazolium bromide) assay test exhibited that etoposide-loaded calcium carbonate nanobelts (ECCNBs) showed a higher cell kill ratio against SGC-7901 cells compared with free drug. The apoptosis test and cell cycle test analysis revealed that etoposide entrapped in calcium carbonate nanobelts (CCNBs) could enhance the delivery efficiencies of drug and improved inhibition effect. The present findings demonstrated that ECCNBs might induce cell cycle arrest at G2/M phase and cell apoptosis in a p53-related manner. It can be foreseen that CCNBs are a promising drug carrier to store the anti-cancer drug for cancer therapy and drug delivery.

Doxorubicin induces apoptosis in Jurkat cells by mitochondria-dependent and mitochondria-independent mechanisms under normoxic and hypoxic conditions

In this study, we investigated the molecular mechanism of doxorubicin (dxr)-induced cytotoxicity on Jurkat cells - a model cell of human acute lymphoblastic leukemia - under normoxic (20% O2) and hypoxic (5% O2) conditions. Using in-cell western analysis, immunofluorescence, flow cytometry analysis, and biochemical inhibitors, we evaluated several oxidative stress (OS) and cell death markers. It was found that dxr (5-100 μmol/l) induced apoptosis by OS mechanisms involving DNA fragmentation (8-48%), loss of mitochondrial membrane potential (ΔΨm, 33-92%), and H2O2 production (15-42%) under normoxia. In addition, dxr (10 μmol/l) induced activation and/or nuclei translocation of NF-κB (6.6, 1.6-fold increase), p53 (4.3, 3.1 f), c-Jun (9.5, 5.0 f), apoptosis-inducing factor (AIF) (1.9, 3.9 f), caspase-3 (3.7, 1.9 f), overexpression of Parkin (2.1, 1.2 f)/PINK-1 (2.1 f) proteins, and reduced DJ-1 levels by half compared with untreated cells under normoxia, according to immunofluorescence and in-cell western analysis, respectively. In contrast, dxr (10 μmol/l) could not induce apoptosis in Jurkat cells under hypoxia. Effectively, dxr significantly reduced DNA fragmentation (6%), expression levels of cell death (e.g. p53, c-Jun, caspase-3, AIF), and OS (e.g. Parkin) markers, whereas it increased ΔΨm, hypoxia-inducible factor 1-α (HIF-1α, 3.1, 2.3 f), NF-κB (6.8, 2.0 f), and DJ-1 (1.3, 1.0 f) levels. This investigation suggests that dxr might efficiently eliminate acute lymphoblastic leukemia cells by OS-induced apoptosis under normoxic conditions through a minimal completeness of cell death signaling (i.e. mitochondria-caspase-3/AIF-dependent pathways) and through a direct DNA damage process. However, hypoxic conditions may reduce the effectiveness of dxr toxicity.

B7-H4 downregulation induces mitochondrial dysfunction and enhances doxorubicin sensitivity via the cAMP/CREB/PGC1-α signaling pathway in HeLa cells

B7-H4 is a B7 family coregulatory protein that inhibits T cell-mediated immunity. B7-H4 is overexpressed in various cancers; however, the functional role of B7-H4 in cancer metabolism is poorly understood. Because mitochondria play pivotal roles in development, proliferation, and death of cancer cells, we investigated molecular and functional alterations of mitochondria in B7-H4-depleted HeLa cells. In a human study, overexpression of B7-H4 was confirmed in the cervices of adenocarcinoma patients (n = 3) compared to noncancer patients (n = 3). In the cell line model, B7-H4 depletion was performed by transfection with small interfering RNA (siRNA). B7-H4 depletion suppressed oxygen consumption rate, ATP production, and mitochondrial membrane potential and mass and increased reactive oxygen species production. In particular, electron transport complex III activity was significantly impaired in siB7-H4-treated cells. Coincidently, depletion of B7-H4 suppressed major mitochondrial regulators (peroxisome proliferator-activated receptor gamma coactivator 1-alpha [PGC1-α] and mitochondrial transcription factor A), a component of oxidative phosphorylation (ubiquinol-cytochrome c reductase core protein 1), and an antiapoptosis protein (Bcl-XL). Mitochondrial dysfunction in siRNA-treated cells significantly augmented oxidative stress, which strongly activated the JNK/P38/caspase axis in the presence of doxorubicin, resulting in increased apoptotic cell death. Investigating the mechanism of B7-H4-mediated mitochondrial modulation, we found that B7-H4 depletion significantly downregulated the cAMP/cAMP response element-binding protein/PGC1-α signaling pathway. Based on these findings, we conclude that B7-H4 has a role in the regulation of mitochondrial function, which is closely related to cancer cell physiology and drug sensitivity.

Sirtuin 7 promotes cellular survival following genomic stress by attenuation of DNA damage, SAPK activation and p53 response

Maintaining the genomic integrity is a constant challenge in proliferating cells. Amongst various proteins involved in this process, Sirtuins play a key role in DNA damage repair mechanisms in yeast as well as mammals. In the present work we report the role of one of the least explored Sirtuin viz., SIRT7, under conditions of genomic stress when treated with doxorubicin. Knockdown of SIRT7 sensitized osteosarcoma (U2OS) cells to DNA damage induced cell death by doxorubicin. SIRT7 overexpression in NIH3T3 delayed cell cycle progression by causing delay in G1 to S transition. SIRT7 overexpressing cells when treated with low dose of doxorubicin (0.25 µM) showed delayed onset of senescence, lesser accumulation of DNA damage marker γH2AX and lowered levels of growth arrest markers viz., p53 and p21 when compared to doxorubicin treated control GFP expressing cells. Resistance to DNA damage following SIRT7 overexpression was also evident by EdU incorporation studies where cellular growth arrest was significantly delayed. When treated with higher dose of doxorubicin (>1 µM), SIRT7 conferred resistance to apoptosis by attenuating stress activated kinases (SAPK viz., p38 and JNK) and p53 response thereby shifting the cellular fate towards senescence. Interestingly, relocalization of SIRT7 from nucleolus to nucleoplasm together with its co-localization with SAPK was an important feature associated with DNA damage. SIRT7 mediated resistance to doxorubicin induced apoptosis and senescence was lost when p53 level was restored by nutlin treatment. Overall, we propose SIRT7 attenuates DNA damage, SAPK activation and p53 response thereby promoting cellular survival under conditions of genomic stress.

Guibitang, a traditional herbal medicine, induces apoptotic death in A431 cells by regulating the activities of mitogen-activated protein kinases

Background

Guibi-tang (GBT), a traditional herbal formula, mainly has been shown to possess immune regulation, antioxidant and protective effect of the gastric mucosa. Constituent herbs of GBT are frequently used to treat various diseases; however, their pharmacological effects, especially on cancer cells, differ from those of GBT. Furthermore, the molecular mechanisms behind effects of GBT remain unclear. In the present study, we explored the mechanism of chemopreventive/chemotherapeutic efficacy of GBT against human squamous cell carcinoma without cytotoxicity in normal cells and proved the efficacy of GBT through performing in vivo xenograft assay.

Methods

For analysis of the constituents of GBT, high performance liquid chromatography (HPLC)-DAD system was performed. To detect the anticancer effect of GBT, cell viability assay, caspase activity assay, cell cycle analysis, DNA fragmentation analysis, and Western blot analysis were performed in A431 cells. In addition, the inhibitory effect of tumor growth by GBT was evaluated in athymic nude mice inoculated with A431 cells.

Results

GBT showed cytotoxic activity against three different squamous cell carcinoma, especially on A431 cells. GBT induced the apoptosis through activating the caspase-8 in A431 cells. Inhibition of A431 cell growth by GBT was caused by G1-phase arrest through regulating proteins associated with cell cycle progression, such as cyclin D1, p21, and p27. Furthermore, GBT regulated the activation of mitogen-activated protein kinases (MAPKs) including extracellular signal-regulated kinase (ERK), p38 and c-Jun NH2-terminal kinase (JNK), and activated p53, a tumor suppressor protein. In MAPKs inhibitor study, inhibitors respectively blocked GBT-induced cell viability, indicating that MAPKs signals play critical role in cell death caused by GBT. In vivo xenografts, daily oral administration of 600 mg/kg GBT efficiently suppressed the tumorigenic growth of A431 cells without side effects such as loss of body weight and change of toxicological parameters compared to vehicle.

Conclusions

We first elucidate that GBT stimulates the apoptotic signaling pathway and suppresses the proliferation of A431 cells via regulating MAPKs signaling pathway. Furthermore, GBT significantly inhibits tumor growth of A431 cells without causing systemic toxicity. Based on our study, GBT could be useful in the management of skin cancer as chemoprevention and chemotherapy remedy.

Enhancement of the anti-tumor effect of DNA vaccination using an ultrasound-responsive mannose-modified gene carrier in combination with doxorubicin-encapsulated PEGylated liposomes

A method involving the use of doxorubicin-loaded polyethylene-glycol-modified liposomes and transfection using mannose-modified bubble lipoplexes in combination with ultrasound irradiation may be a promising approach to cancer treatment; it could not only suppress early-stage tumor growth but also enhance transfection efficacy in antigen-presenting cells, thus enhancing the therapeutic potential of a DNA vaccine. However, to date only limited research has been carried out regarding this combination DNA vaccination method for use in cancer therapy. In this study, we examined the anti-tumor effect of DNA vaccination using an ultrasound-responsive mannose-modified gene carrier combined with doxorubicin-encapsulated polyethylene-glycol-modified liposomes. Doxorubicin-encapsulated PEGylated liposomes activated transcriptional factors, such as nuclear factor-κB and AP-1 in the spleen; subsequently pUb-M, ubiquitylated melanoma-related antigen encoding plasmid DNA expression in splenic cells was significantly enhanced. Moreover, effective cytotoxic T-lymphocyte activities were stimulated by DNA vaccination combined with the administration of doxorubicin-encapsulated polyethylene-glycol-modified liposomes. Furthermore, potent DNA vaccine effects against established solid tumor and metastatic tumor derived from B16BL6 melanoma were observed. These results suggest that the combined use of DNA vaccination with doxorubicin-encapsulated polyethylene-glycol-modified liposomes could be an effective method for the treatment of melanoma using immunotherapy.

Discovery and investigation of anticancer ruthenium-arene Schiff-base complexes via water-promoted combinatorial three-component assembly

The structural diversity of metal scaffolds makes them a viable alternative to traditional organic scaffolds for drug design. Combinatorial chemistry and multicomponent reactions, coupled with high-throughput screening, are useful techniques in drug discovery, but they are rarely used in metal-based drug design. We report the optimization and validation of a new combinatorial, metal-based, three-component assembly reaction for the synthesis of a library of 442 Ru-arene Schiff-base (RAS) complexes. These RAS complexes were synthesized in a one-pot, on-a-plate format using commercially available starting materials under aqueous conditions. The library was screened for their anticancer activity, and several cytotoxic lead compounds were identified. In particular, [(η6-1,3,5-triisopropylbenzene)RuCl(4-methoxy-N-(2-quinolinylmethylene)aniline)]Cl (4) displayed low micromolar IC50 values in ovarian cancers (A2780, A2780cisR), breast cancer (MCF7), and colorectal cancer (HCT116, SW480). The absence of p53 activation or changes in IC50 value between p53+/+ and p53-/- cells suggests that 4 and possibly the other lead compounds may act independently of the p53 tumor suppressor gene frequently mutated in cancer.

Microtubules and their role in cellular stress in cancer

Microtubules are highly dynamic structures, which consist of α- and β-tubulin heterodimers, and are involved in cell movement, intracellular trafficking, and mitosis. In the context of cancer, the tubulin family of proteins is recognized as the target of the tubulin-binding chemotherapeutics, which suppress the dynamics of the mitotic spindle to cause mitotic arrest and cell death. Importantly, changes in microtubule stability and the expression of different tubulin isotypes as well as altered post-translational modifications have been reported for a range of cancers. These changes have been correlated with poor prognosis and chemotherapy resistance in solid and hematological cancers. However, the mechanisms underlying these observations have remained poorly understood. Emerging evidence suggests that tubulins and microtubule-associated proteins may play a role in a range of cellular stress responses, thus conferring survival advantage to cancer cells. This review will focus on the importance of the microtubule-protein network in regulating critical cellular processes in response to stress. Understanding the role of microtubules in this context may offer novel therapeutic approaches for the treatment of cancer.

Epicatechin gallate induces cell death via p53 activation and stimulation of p38 and JNK in human colon cancer SW480 cells

The tea flavonoid epicatechin gallate (ECG) exhibits a wide range of biological activities. In this study, the in vitro anticancer effects of ECG on SW480 colon cancer cell line was investigated by analyzing the cell cycle, apoptosis, key proteins involved in cellular survival/proliferation, namely AKT/phosphatidylinositol-3-kinase (PI3K) and mitogen-activated protein kinases (MAPKs), and the role of p53 in these processes. ECG induced cell cycle arrest at the G0/G1-S phase border associated with the stimulation of p21, p-p53, and p53 and the suppression of cyclins D1 and B1. Exposure of SW480 cells to ECG also led to apoptosis as determined by time-dependent changes in caspase-3 activity, MAPKs [extracellular regulated kinase (ERK), p38, and c-jun amino-terminal kinase (JNK)], p21 and p53 activation, and AKT inhibition. The presence of pifithrin, an inhibitor of p53 function, blocked ECG-induced apoptosis as was manifested by restored cell viability and caspase-3 activity to control values and reestablished the balance among Bcl-2 anti- and proapoptotic protein levels. Interestingly, ECG also inhibited p53 protein and RNA degradation, contributing to the stabilization of p53. In addition, JNK and p38 have been identified as necessary for ECG-induced apoptosis, upon activation by p53. The results suggest that the activation of the p53-p38/JNK cascade is required for ECG-induced cell death in SW480 cells.

Mangiferin activates Nrf2-antioxidant response element signaling without reducing the sensitivity to etoposide of human myeloid leukemia cells in vitro

AIM

Mangiferin is glucosylxanthone extracted from plants of the Anacardiaceae and Gentianaceae families. The aim of this study was to investigate the effects of mangiferin on Nrf2-antioxidant response element (ARE) signaling and the sensitivity to etoposide of human myeloid leukemia cells in vitro.

METHODS

Human HL-60 myeloid leukemia cells and mononuclear human umbilical cord blood cells (MNCs) were examined. Nrf2 protein was detected using immunofluorescence staining and Western blotting. Binding of Nrf2 to ARE was examined with electrophoretic mobility shift assay. The level of NQO1 was assessed with real-time RT-PCR and Western blotting. DCFH-DA was used to evaluate intracellular ROS level. Cell proliferation and apoptosis were analyzed using MTT and flow cytometry, respectively.

RESULTS

Mangiferin (50 μmol/L) significantly increased Nrf2 protein accumulation in HL-60 cells, particularly in the nucleus. Mangiferin also enhanced the binding of Nrf2 to an ARE, significantly up-regulated NQO1 expression and reduced intracellular ROS in HL60 cells. Mangiferin alone dose-dependently inhibited the proliferation of HL-60 cells. Mangiferin (50 mol/L) did not attenuate etoposide-induced cytotoxicity in HL-60 cells, and combined treatment of mangiferin with low concentration of etoposide (0.8 μg/mL) even increased the cell inhibition rate. Nor did mangiferin change the rate of etoposide-induced apoptosis in HL-60 cells. In MNCs, mangiferin significantly relieved oxidative stress, but attenuated etoposide-induced cytotoxicity.

CONCLUSION

Mangiferin is a novel Nrf2 activator that reduces oxidative stress and protects normal cells without reducing the sensitivity to etoposide of HL-60 leukemia cells in vitro. Mangiferin may be a potential chemotherapy adjuvant.

Tetramethylpyrazine induces G0/G1 cell cycle arrest and stimulates mitochondrial-mediated and caspase-dependent apoptosis through modulating ERK/p53 signaling in hepatic stellate cells in vitro

Activation of hepatic stellate cells (HSCs) is a pivotal event in the pathogenesis of liver fibrosis. Pharmacological induction of HSC apoptosis could be a promising strategy for fibrosis regression. Natural product tetramethylpyrazine (TMP) exhibits potent antifibrotic activities in vivo. However, the molecular mechanisms remain to be defined. The present study aimed at investigating the anti-proliferative and pro-apoptotic effects of TMP on HSCs and elucidating the underlying mechanisms. Our results demonstrated that TMP had no apparent cytotoxic effects on hepatocytes, but significantly inhibited HSC proliferation and induced cell cycle arrest at the G0/G1 checkpoint. These effects were associated with TMP regulation of cyclin D1, p21, p27 and p53. Furthermore, we found that TMP disrupted mitochondrial functions and led to activation of caspase cascades in HSCs. Mechanistic investigations revealed that TMP selectively blocked the extracellular signal-regulated kinase (ERK) signaling and activated p53, which was required for TMP induction of caspase-dependent mitochondrial apoptosis in HSCs. Autodock simulations predicted that TMP could directly bind to ERK2 with two hydrogen bonds and low energy score, indicating that ERK2 could be a direct target molecule for TMP within HSCs. Moreover, TMP altered expression of some marker proteins relevant to HSC activation. These data collectively revealed that TMP modulation of ERK/p53 signaling led to mitochondrial-mediated and caspase-dependent apoptosis in HSCs in vitro. These studies provided mechanistic insights into the antifibrotic properties of TMP that may be exploited as a potential option for hepatic fibrosis.

Isorhamnetin protects against doxorubicin-induced cardiotoxicity in vivo and in vitro

Doxorubicin (Dox) is an anthracycline antibiotic for cancer therapy with limited usage due to cardiotoxicity. Isorhamnetin is a nature antioxidant with obvious cardiac protective effect. The aim of this study is going to investigate the possible protective effect of isorhamnetin against Dox-induced cardiotoxicity and its underlying mechanisms. In an in vivo investigation, rats were intraperitoneally (i.p.) administered with Dox to duplicate the model of Dox-induced chronic cardiotoxicity. Daily pretreatment with isorhamnetin (5 mg/kg, i.p.) for 7 days was found to reduce Dox-induced myocardial damage significantly, including the decline of cardiac index, decrease in the release of serum cardiac enzymes and amelioration of heart vacuolation. In vitro studies on H9c2 cardiomyocytes, isorhamnetin was effective to reduce Dox-induced cell toxicity. A further mechanism study indicated that isorhamnetin pretreatment can counteract Dox-induced oxidative stress and suppress the activation of mitochondrion apoptotic pathway and mitogen-activated protein kinase pathway. Isorhamnetin also potentiated the anti-cancer activity of Dox in MCF-7, HepG2 and Hep2 cells. These findings indicated that isorhamnetin can be used as an adjuvant therapy for the long-term clinical use of Dox.

DC-81-enediyne induces apoptosis of human melanoma A375 cells: involvement of the ROS, p38 MAPK, and AP-1 signaling pathways

Melanoma is one of the most chemoresistant cancers in patient care. The remission rate of current therapy remains low. DC-81, an antitumor antibiotic produced by Streptomyces species, belongs to pyrrolo[2,1-c][1,4]benzodiazepine (PBD), which is a potent inhibitor of nucleic acid synthesis. An enediyne contains either DNA intercalating groups or DNA minor groove binding functions and these are potent DNA-damaging agents due to their ability to generate benzenoid diradicals. We have previously reported an efficient synthesis and antitumor activity of a series of novel PBD hybrids linked with enediyne. The purpose of this study was to examine the mechanism of the antiproliferative effect of DC-81-enediyne agent on human melanoma A375 cells. DC-81-enediyne induced an increase in Ca(2+) level and reactive oxygen species (ROS) generation as detected by flow cytometric assay. Western blot analysis showed that DC-81-enediyne induced the phosphorylation of p38 and activating transcription factor 2 (ATF-2). By using the luciferase reporter assay, activating protein-1 (AP-1) activity was further enhanced after A375 cells were treated with graded concentrations of DC-81-enediyne. DC-81-enediyne treatment-induced A375 cell apoptosis was significantly abrogated by the addition of Ca(2+), ROS, and p38 inhibitors. Collectively, our studies indicate that DC-81-enediyne induces A375 cell apoptosis through an increased Ca(2+) and ROS generation, which involves p38 phosphorylation and enhanced ATF-2/AP-1 expressions, leading to caspase-3 activity, poly(ADP-ribose)polymerase cleavage, M30 CytoDeath staining, and subsequent apoptotic cell death.

Induction of p53, p21 and apoptosis by silencing the NF90/NF45 complex in human papilloma virus-transformed cervical carcinoma cells

The heterodimeric nuclear factor 90/nuclear factor 45 complex (NF90/NF45) binds nucleic acids and is a multifunctional regulator of gene expression. Here we report that depletion of NF90/NF45 restores the expression of the p53 and p21 proteins in cervical carcinoma cells infected with high-risk human papillomaviruses (HPV). Knockdown of either NF90 or NF45 by RNA interference led to greatly elevated levels of p53 and p21 proteins in HPV-derived HeLa and SiHa cells, but not in other cancerous or normal cell lines. In HeLa cells, p21 mRNA increased concomitantly but the level of p53 mRNA was unaffected. RNA interference directed against p53 prevented the induction of both proteins. These results indicated that the up-regulation of p21 is due to p53-dependent transcription, whereas p53 is regulated post-transcriptionally. Proteasome-mediated turnover of p53 is accelerated by the HPV E6 and cellular E6AP proteins. We therefore examined the hypothesis that this pathway is regulated by NF90/NF45. Indeed, depletion of NF90 attenuated the expression of E6 RNA and inhibited transcription from the HPV early promoter, revealing a new role for NF90/NF45 in HPV gene expression. The transcription inhibition was largely independent of the reduction of P-TEFb levels caused by NF90 depletion. Consistent with p53 derepression, NF90/NF45-depleted HeLa cells displayed elevated PARP cleavage and susceptibility to camptothecin-induced apoptosis. We conclude that high-risk strains of HPV utilize the cellular NF90/NF45 complex for viral E6 expression in infected cervical carcinoma cell lines. Interference with NF90/NF45 function could assist in controlling cervical carcinoma.

ERK1/2 signaling plays an important role in topoisomerase II poison-induced G2/M checkpoint activation

Topo II poisons, which target topoisomerase II (topo II) to generate enzyme mediated DNA damage, have been commonly used for anti-cancer treatment. While clinical evidence demonstrate a capability of topo II poisons in inducing apoptosis in cancer cells, accumulating evidence also show that topo II poison treatment frequently results in cell cycle arrest in cancer cells, which was associated with subsequent resistance to these treatments. Results in this report indicate that treatment of MCF-7 and T47D breast cancer cells with topo II poisons resulted in an increased phosphorylation of extracellular signal-regulated kinase 1 and 2 (ERK1/2) and an subsequent induction of G2/M cell cycle arrest. Furthermore, inhibition of ERK1/2 activation using specific inhibitors markedly attenuated the topo II poison-induced G2/M arrest and diminished the topo II poison-induced activation of ATR and Chk1 kinases. Moreover, decreased expression of ATR by specific shRNA diminished topo II poison-induced G2/M arrest but had no effect on topo II poison-induced ERK1/2 activation. In contrast, inhibition of ERK1/2 signaling had little, if any, effect on topo II poison-induced ATM activation. In addition, ATM inhibition by either incubation of cells with ATM specific inhibitor or transfection of cells with ATM specific siRNA did not block topo II poison-induced G2/M arrest. Ultimately, inhibition of ERK1/2 signaling greatly enhanced topo II poison-induced apoptosis. These results implicate a critical role for ERK1/2 signaling in the activation of G2/M checkpoint response following topo II poison treatment, which protects cells from topo II poison-induced apoptosis.