Role of p53 and reactive oxygen species in apoptotic response to copper and zinc in epithelial breast cancer cells

Zinc Oxide Nanoparticles and Cancer Chemotherapy: Helpful Tools for Enhancing Chemo-sensitivity and Reducing Side Effects?

Cancer chemotherapy is still a serious challenge. Chemo-resistance and destructive side effects of chemotherapy drugs are the most critical limitations of chemotherapy. Chemo-resistance is the leading cause of chemotherapy failure. Chemo-resistance, which refers to the resistance of cancer cells to the anticancer effects of chemotherapy drugs, is caused by various reasons. Among the most important of these reasons is the increase in the efflux of chemotherapy drugs due to the rise in the expression and activity of ABC transporters, the weakening of apoptosis, and the strengthening of stemness. In the last decade, a significant number of studies focused on the application of nanotechnology in cancer treatment. Considering the anti-cancer properties of zinc, zinc oxide nanoparticles have received much attention in recent years. Some studies have indicated that zinc oxide nanoparticles can target the critical mechanisms of cancer chemo-resistance and enhance the effectiveness of chemotherapy drugs. These studies have shown that zinc oxide nanoparticles can reduce the activity of ABC transporters, increase DNA damage and apoptosis, and attenuate stemness in cancer cells, leading to enhanced chemo-sensitivity. Some other studies have also shown that zinc oxide nanoparticles in low doses can be helpful in minimizing the harmful side effects of chemotherapy drugs. In this article, after a brief overview of the mechanisms of chemo-resistance and anticancer effects of zinc, we will review all these studies in detail.

A Responsive Nanorobot Modulates Intracellular Zinc Homeostasis to Amplify Mitochondria-Targeted Phototherapy

Zinc has been proven to interweave with many critical cell death pathways, and not only exhibits potent anticancer activity solely, but sensitizes cancer cells to anticancer treatment, making zinc supplementation ideal for boosting odds against malignancy. Herein, a smart nanorobot (termed as Zinger) is developed, composed of iRGD-functionalized liposome encapsulating black phosphorus nanosheet (BPNs) doped zeolite imidazole framework-8 (BPN@ZIF-8), for advancing zinc-promoted photodynamic therapy (PDT). Zinger exhibits photo-triggered sequential mitochondria-targeting ability, and can induce zinc overload-mediated mitochondrial stress, which consequently sensitized tumor to PDT through synergistically modulating reactive oxygen species (ROS) production and p53 pathway. It is identified that Zinger selectively triggered intracellular zinc overload and photodynamic effect in cancer cells, which together enhanced PDT treatment outcomes. Importantly, Zinger shows high efficacy in overcoming various treatment barriers, allowing for effectively killing cancer cells in the complex circumstances. Particularly, Zinger exhibits good tumor accumulation, penetration, and even cell uptake, and can respond to light stimulation to eliminate tumors while avoiding normal tissues, thereby prolonging survival of tumor-bearing mice. Therefore, the study provides a novel insight in the development of novel zinc-associated therapy for advancing cancer treatment approaches.

Copper-instigated modulatory cell mortality mechanisms and progress in oncological treatment investigations

Copper, a transition metal, serves as an essential co-factor in numerous enzymatic active sites and constitutes a vital trace element in the human body, participating in crucial life-sustaining activities such as energy metabolism, antioxidation, coagulation, neurotransmitter synthesis, iron metabolism, and tetramer deposition. Maintaining the equilibrium of copper ions within biological systems is of paramount importance in the prevention of atherosclerosis and associated cardiovascular diseases. Copper induces cellular demise through diverse mechanisms, encompassing reactive oxygen species responses, apoptosis, necrosis, pyroptosis, and mitochondrial dysfunction. Recent research has identified and dubbed a novel regulatory cell death modality-"cuprotosis"-wherein copper ions bind to acylated proteins in the tricarboxylic acid cycle of mitochondrial respiration, resulting in protein aggregation, subsequent downregulation of iron-sulfur cluster protein expression, induction of proteotoxic stress, and eventual cell death. Scholars have synthesized copper complexes by combining copper ions with various ligands, exploring their significance and applications in cancer therapy. This review comprehensively examines the multiple pathways of copper metabolism, copper-induced regulatory cell death, and the current status of copper complexes in cancer treatment.

Copper metabolism in cell death and autophagy

Copper is an essential trace element in biological systems, maintaining the activity of enzymes and the function of transcription factors. However, at high concentrations, copper ions show increased toxicity by inducing regulated cell death, such as apoptosis, paraptosis, pyroptosis, ferroptosis, and cuproptosis. Furthermore, copper ions can trigger macroautophagy/autophagy, a lysosome-dependent degradation pathway that plays a dual role in regulating the survival or death fate of cells under various stress conditions. Pathologically, impaired copper metabolism due to environmental or genetic causes is implicated in a variety of human diseases, such as rare Wilson disease and common cancers. Therapeutically, copper-based compounds are potential chemotherapeutic agents that can be used alone or in combination with other drugs or approaches to treat cancer. Here, we review the progress made in understanding copper metabolic processes and their impact on the regulation of cell death and autophagy. This knowledge may help in the design of future clinical tools to improve cancer diagnosis and treatment.Abbreviations: ACSL4, acyl-CoA synthetase long chain family member 4; AIFM1/AIF, apoptosis inducing factor mitochondria associated 1; AIFM2, apoptosis inducing factor mitochondria associated 2; ALDH, aldehyde dehydrogenase; ALOX, arachidonate lipoxygenase; AMPK, AMP-activated protein kinase; APAF1, apoptotic peptidase activating factor 1; ATF4, activating transcription factor 4; ATG, autophagy related; ATG13, autophagy related 13; ATG5, autophagy related 5; ATOX1, antioxidant 1 copper chaperone; ATP, adenosine triphosphate; ATP7A, ATPase copper transporting alpha; ATP7B, ATPase copper transporting beta; BAK1, BCL2 antagonist/killer 1; BAX, BCL2 associated X apoptosis regulator; BBC3/PUMA, BCL2 binding component 3; BCS, bathocuproinedisulfonic acid; BECN1, beclin 1; BID, BH3 interacting domain death agonist; BRCA1, BRCA1 DNA repair associated; BSO, buthionine sulphoximine; CASP1, caspase 1; CASP3, caspase 3; CASP4/CASP11, caspase 4; CASP5, caspase 5; CASP8, caspase 8; CASP9, caspase 9; CCS, copper chaperone for superoxide dismutase; CD274/PD-L1, CD274 molecule; CDH2, cadherin 2; CDKN1A/p21, cyclin dependent kinase inhibitor 1A; CDKN1B/p27, cyclin-dependent kinase inhibitor 1B; COMMD10, COMM domain containing 10; CoQ10, coenzyme Q 10; CoQ10H2, reduced coenzyme Q 10; COX11, cytochrome c oxidase copper chaperone COX11; COX17, cytochrome c oxidase copper chaperone COX17; CP, ceruloplasmin; CYCS, cytochrome c, somatic; DBH, dopamine beta-hydroxylase; DDIT3/CHOP, DNA damage inducible transcript 3; DLAT, dihydrolipoamide S-acetyltransferase; DTC, diethyldithiocarbamate; EIF2A, eukaryotic translation initiation factor 2A; EIF2AK3/PERK, eukaryotic translation initiation factor 2 alpha kinase 3; ER, endoplasmic reticulum; ESCRT-III, endosomal sorting complex required for transport-III; ETC, electron transport chain; FABP3, fatty acid binding protein 3; FABP7, fatty acid binding protein 7; FADD, Fas associated via death domain; FAS, Fas cell surface death receptor; FASL, Fas ligand; FDX1, ferredoxin 1; GNAQ/11, G protein subunit alpha q/11; GPX4, glutathione peroxidase 4; GSDMD, gasdermin D; GSH, glutathione; HDAC, histone deacetylase; HIF1, hypoxia inducible factor 1; HIF1A, hypoxia inducible factor 1 subunit alpha; HMGB1, high mobility group box 1; IL1B, interleukin 1 beta; IL17, interleukin 17; KRAS, KRAS proto-oncogene, GTPase; LOX, lysyl oxidase; LPCAT3, lysophosphatidylcholine acyltransferase 3; MAP1LC3, microtubule associated protein 1 light chain 3; MAP2K1, mitogen-activated protein kinase kinase 1; MAP2K2, mitogen-activated protein kinase kinase 2; MAPK, mitogen-activated protein kinases; MAPK14/p38, mitogen-activated protein kinase 14; MEMO1, mediator of cell motility 1; MT-CO1/COX1, mitochondrially encoded cytochrome c oxidase I; MT-CO2/COX2, mitochondrially encoded cytochrome c oxidase II; MTOR, mechanistic target of rapamycin kinase; MTs, metallothioneins; NAC, N-acetylcysteine; NFKB/NF-Κb, nuclear factor kappa B; NLRP3, NLR family pyrin domain containing 3; NPLOC4/NPL4, NPL4 homolog ubiquitin recognition factor; PDE3B, phosphodiesterase 3B; PDK1, phosphoinositide dependent protein kinase 1; PHD, prolyl-4-hydroxylase domain; PIK3C3/VPS34, phosphatidylinositol 3-kinase catalytic subunit type 3; PMAIP1/NOXA, phorbol-12-myristate-13-acetate-induced protein 1; POR, cytochrome P450 oxidoreductase; PUFA-PL, PUFA of phospholipids; PUFAs, polyunsaturated fatty acids; ROS, reactive oxygen species; SCO1, synthesis of cytochrome C oxidase 1; SCO2, synthesis of cytochrome C oxidase 2; SLC7A11, solute carrier family 7 member 11; SLC11A2/DMT1, solute carrier family 11 member 2; SLC31A1/CTR1, solute carrier family 31 member 1; SLC47A1, solute carrier family 47 member 1; SOD1, superoxide dismutase; SP1, Sp1 transcription factor; SQSTM1/p62, sequestosome 1; STEAP4, STEAP4 metalloreductase; TAX1BP1, Tax1 binding protein 1; TEPA, tetraethylenepentamine; TFEB, transcription factor EB; TM, tetrathiomolybdate; TP53/p53, tumor protein p53; TXNRD1, thioredoxin reductase 1; UCHL5, ubiquitin C-terminal hydrolase L5; ULK1, Unc-51 like autophagy activating kinase 1; ULK1, unc-51 like autophagy activating kinase 1; ULK2, unc-51 like autophagy activating kinase 2; USP14, ubiquitin specific peptidase 14; VEGF, vascular endothelial gro wth factor; XIAP, X-linked inhibitor of apoptosis.

Uncovering the Interaction between Intracellular Telomerase Activity and Hydrogen Peroxide during Cancer Cell Apoptosis Utilizing a Dual-Color Fluorescent Nanoprobe

Uncovering the intrinsic interaction of different bioactive species, i.e., reactive oxygen species (ROS) and telomerase, is of great importance because they play interrelated and interdependent biological roles in living organisms. Nevertheless, exploration of the intracellular ROS/telomerase cross-talk by effective and noninvasive methods remains a great challenge, as it is difficult to simultaneously detect different types of biomolecules (i.e., active small molecules and proteins) in living cells. To address this issue, herein, we report, for the first time, a novel fluorescent nanoprobe for simultaneous determination and in situ imaging of telomerase activity and hydrogen peroxide (H₂O₂) in living cells. With the advantage of high sensitivity and good specificity, this newly fabricated nanoprobe was successfully applied to precisely visualize and monitor the changes in telomerase activity and H₂O₂ concentration in cancer cells. More significantly, by employing the nanoprobe as a one-step incubation tool, it is found that there is a cross-talk between H₂O₂ and telomerase activity in the drug-induced cancer cells' apoptosis process, which provides valuable information for gaining fundamental insights into the relationship between ROS and telomerase activity in cancer treatments. This work affords a promising method for revealing the relevant regulatory mechanisms and roles of ROS and telomerase activity in the occurrence, evolvement, and treatment of diseases.

In situ monitoring of the effect of Cu2+ on the membrane permeability of a single living cell with a dual-electrode tip of a scanning electrochemical microscope

Here, an Au-Cu dual-electrode tip was designed to monitor the effect of Cu²⁺ on the membrane permeability of a single living cell in situ using scanning electrochemical microscopy. The probe approach curves (PACs) were obtained using potassium ferricyanide as a redox mediator. Meanwhile, according to the simulation, theoretical PACs could be acquired. Thus, the cell membrane permeability coefficient (P_m) values were obtained by overlapping the experimental PACs with the theoretical values. Cu²⁺ was directly generated by electrolyzing the Cu electrode of the dual-electrode tip to investigate its effect on the cell membrane permeability in situ. This work has potential value to improve the understanding of the mechanism of acute heavy metal damage on the cell membrane and will also help clarify the role of heavy metal ions in physiological or pathological processes.

Innovative therapies for neuroblastoma: The surprisingly potent role of iron chelation in up-regulating metastasis and tumor suppressors and down-regulating the key oncogene, N-myc

Iron is an indispensable requirement for essential biological processes in cancer cells. Due to the greater proliferation of neoplastic cells, their demand for iron is considerably higher relative to normal cells, making them highly susceptible to iron depletion. Understanding this sensitive relationship led to research exploring the effect of iron chelation therapy for cancer treatment. The classical iron-binding ligand, desferrioxamine (DFO), has demonstrated effective anti-proliferative activity against many cancer-types, particularly neuroblastoma tumors, and has the surprising activity of down-regulating the potent oncogene, N-myc, which is a major oncogenic driver in neuroblastoma. Even more significant is the ability of DFO to simultaneously up-regulate the potent metastasis suppressor, N-myc downstream-regulated gene-1 (NDRG1), which plays a plethora of roles in suppressing a variety of oncogenic signaling pathways. However, DFO suffers the disadvantage of demonstrating poor membrane permeability and short plasma half-life, requiring administration by prolonged subcutaneous or intravenous infusions. Considering this, the specifically designed di-2-pyridylketone thiosemicarbazone (DpT) series of metal-binding ligands was developed in our laboratory. The lead agent from the first generation DpT series, di-2-pyridylketone-4,4-dimethyl-3-thiosemicarbazone (Dp44mT), showed exceptional anti-cancer properties compared to DFO. However, it exhibited cardiotoxicity in mouse models at higher dosages. Therefore, a second generation of agents was developed with the lead compound being di-2-pyridylketone-4-cyclohexyl-4-methyl-3-thiosemicarbazone (DpC) that progressed to Phase I clinical trials. Importantly, DpC showed better anti-proliferative activity than Dp44mT and no cardiotoxicity, demonstrating effective anti-cancer activity against neuroblastoma tumors in vivo.

Copper: An Intracellular Achilles' Heel Allowing the Targeting of Epigenetics, Kinase Pathways, and Cell Metabolism in Cancer Therapeutics

Copper is an essential transition metal frequently increased in cancer known to strongly influence essential cellular processes. Targeted therapy protocols utilizing both novel and repurposed drug agents initially demonstrate strong efficacy, before failing in advanced cancers as drug resistance develops and relapse occurs. Overcoming this limitation involves the development of strategies and protocols aimed at a wider targeting of the underlying molecular changes. Receptor Tyrosine Kinase signaling pathways, epigenetic mechanisms and cell metabolism are among the most common therapeutic targets, with molecular investigations increasingly demonstrating the strong influence each mechanism exerts on the others. Interestingly, all these mechanisms can be influenced by intracellular copper. We propose that copper chelating agents, already in clinical trial for multiple cancers, may simultaneously target these mechanisms across a wide variety of cancers, serving as an excellent candidate for targeted combination therapy. This review summarizes the known links between these mechanisms, copper, and copper chelation therapy.

Candesartan and valsartan Zn(ii) complexes as inducing agents of reductive stress: mitochondrial dysfunction and apoptosis

Candesartan and valsartan Zn(ii) complexes as inducing agents of reductive stress, including mitochondrial dysfunction and apoptosis.

High-Dose Vitamin C Exerts Its Anti-cancer Effects in a Xenograft Model of Colon Cancer by Suppressing Angiogenesis

Several studies have been conducted to investigate the anti-cancer effects of vitamin C (VC). However, the effect of high-dose VC administration on tumor angiogenesis remains unclear. Focusing on our high-dose VC, our study investigated the effect of high-dose VC (4 g/kg) on vascular endothelial growth in mice with xenografts of a rectal cancer cell line referred to as Colon 26. Male mice harboring Colon 26 tumors were established, and high-dose VC solution was orally administered once daily for 14 d. On the final day of the study, the lower limb tumor tissues and serum samples were collected and analyzed for the expression of tumor angiogenesis related proteins as well as the levels of reactive oxygen species (ROS). Oral VC administration decreased tumor volumes and increased p53 and endostatin levels. In addition, plasma and in tumor part ROS levels and tissue hypoxia inducible factor-1α (HIF-1α) were reduced by VC administration. In addition, the levels of vascular endothelial growth factor A (VEGFA) and vascular endothelial growth factor D (VEGFD) were decreased by VC administration. These results suggest that VC exerts its anti-cancer effects by suppressing angiogenesis.

Zinc, ω-3 polyunsaturated fatty acids and vitamin D: An essential combination for prevention and treatment of cancers

Zinc, ω-3 polyunsaturated fatty acids (PUFAs) and vitamin D are essential nutrients for health, maturation and general wellbeing. Extensive literature searches have revealed the widespread similarity in molecular biological properties of zinc, ω-3 PUFAs and vitamin D, and their similar anti-cancer properties, even though they have different modes of action. These three nutrients are separately essential for good health, especially in the aged. Zinc, ω-3 PUFAs and vitamin D are inexpensive and safe as they are fundamentally natural and have the properties of correcting and inhibiting undesirable actions without disturbing the normal functions of cells or their extracellular environment. This review of the anticancer properties of zinc, ω-3 PUFAs and vitamin D is made in the context of the hallmarks of cancer. The anticancer properties of zinc, ω-3 PUFAs and vitamin D can therefore be used beneficially through combined treatment or supplementation. It is proposed that sufficiency of zinc, ω-3 PUFAs and vitamin D is a necessary requirement during chemotherapy treatment and that clinical trials can have questionable integrity if this sufficiency is not checked and maintained during efficacy trials.

Myricetin Apoptotic Effects on T47D Breast Cancer Cells is a P53-Independent Approach

Objective:

Using nutraceuticals in cancer therapy is a strategy contributing with other approaches to promote apoptosis in cancer cells. Myricetin is a polyphenol flavonoid that forms main ingredients of various type of foods and beverages. The inducing properties of myricetin in apoptosis is reported by several investigations. The present study aimed to assess apoptotic effects of myricetin on T47D breast cancer cells and to evaluate part of the mechanisms of action.

Materials and Methods:

T47D breast cancer cells were assigned into five groups: control (cells in normal condition), myricetin (cells treated with myricetin IC50 concentration) in two different incubation times (24, 48 and 72 hours). MTT assay, annexin v assay, flow cytometry, caspase-3 assay and Real-time PCR were used to evaluate apoptosis in breast cancer cells.

Results:

The expression rate of apoptotic genes caspase-3, caspase-8, caspase-9, the ratio of BAX /Bcl-2 as well as the expression of P53, BRCA1, GADD45 genes were increased significantly after treatment of T47D breast cancer cells with myricetin. Annexin v assay confirmed significant expression of annexin as were displyed by flow cytometry.

Conclusion:

Myricetin enhances apoptosis in T47D breast cancer cells by evoking both extrinsic and intrinsic apoptotic pathways. myricetin may practices its apoptotic properties on T47D cells through inducing BRCA1- GADD45 pathway.

Targeting ferroptosis in breast cancer

Ferroptosis is a recently discovered distinct type of regulated cell death caused by the accumulation of lipid-based ROS. Metabolism and expression of specific genes affect the occurrence of ferroptosis, making it a promising therapeutic target to manage cancer. Here, we describe the current status of ferroptosis studies in breast cancer and trace the key regulators of ferroptosis back to previous studies. We also compare ferroptosis to common regulated cell death patterns and discuss the sensitivity to ferroptosis in different subtypes of breast cancer. We propose that viewing ferroptosis-related studies from a historical angle will accelerate the development of ferroptosis-based biomarkers and therapeutic strategies in breast cancer.

Reactive Oxygen Species Induced p53 Activation: DNA Damage, Redox Signaling, or Both?

Significance: The p53 tumor suppressor has been dubbed the "guardian of genome" because of its various roles in the response to DNA damage such as DNA damage repair, cell cycle arrest, senescence, and apoptosis, all of which are in place to prevent mutations from being passed on down the lineage. Recent Advances: Reactive oxygen species (ROS), for instance hydrogen peroxide derived from mitochondrial respiration, have long been regarded mainly as a major source of cellular damage to DNA and other macromolecules. Critical Issues: More recently, ROS have been shown to also play important physiological roles as second messengers in so-called redox signaling. It is, therefore, not clear whether the observed activation of p53 by ROS is mediated through the DNA damage response, redox signaling, or both. In this review, we will discuss the similarities and differences between p53 activation in response to DNA damage and redox signaling in terms of upstream signaling and downstream transcriptional program activation. Future Directions: Understanding whether and how DNA damage and redox signaling-dependent p53 activation can be dissected could be useful to develop anti-cancer therapeutic p53-reactivation strategies that do not depend on the induction of DNA damage and the resulting additional mutational load.

Oxidative stress, apoptosis and inflammatory responses involved in copper-induced pulmonary toxicity in mice

At present, there are few studies focused on the relationship between copper (Cu) and oxidative stress, apoptosis, or inflammatory responses in animal and human lungs. This study was conducted to explore the effects of Cu on pulmonary oxidative stress, apoptosis and inflammatory responses in mice orally administered with 0 mg/kg (control), 10 mg/kg, 20 mg/kg, and 40 mg/kg of CuSO₄ for 42 days. The results showed that CuSO₄ increased ROS production, and MDA, 8-OHdG and NO contents as well as iNOS activities and mRNA expression levels. Meanwhile, CuSO₄ reduced the activities and mRNA expression levels of antioxidant enzymes (GSH-Px, CAT, and SOD) and GSH contents, and ASA and AHR abilities. Also, CuSO₄ induced apoptosis, which was accompanied by decreasing Bcl-2, Bcl-xL mRNA expression levels and protein expression levels, and increasing Bax, Bak, cleaved-caspase-3, cleaved-caspase-9 mRNA, and protein expression levels, and Bax/Bcl-2 ratio. Concurrently, CuSO₄ caused inflammation by increasing MPO activities and activating the NF-κB signalling pathway, and down-regulating the mRNA and protein expression levels of anti-inflammatory cytokines (IL-2, IL-4, IL-10). In conclusion, the abovementioned findings demonstrated that over 10 mg/kg CuSO₄ can cause oxidative stress, apoptosis, and inflammatory responses, which contribute to pulmonary lesions and dysfunction in mice.

Frizzled-7-targeted delivery of zinc oxide nanoparticles to drug-resistant breast cancer cells

There is a need for novel strategies to treat aggressive breast cancer subtypes and overcome drug resistance. ZnO nanoparticles (NPs) have potential in cancer therapy due to their ability to potently and selectively induce cancer cell apoptosis. Here, we tested the in vitro chemotherapeutic efficacy of ZnONPs loaded via a mesoporous silica nanolayer (MSN) towards drug-sensitive breast cancer cells (MCF-7: estrogen receptor-positive, CAL51: triple-negative) and their drug-resistant counterparts (MCF-7TX, CALDOX). ZnO-MSNs were coated on to gold nanostars (AuNSs) for future imaging capabilities in the NIR-II range. Electron and confocal microscopy showed that MSN-ZnO-AuNSs accumulated close to the plasma membrane and were internalized by cells. High-resolution electron microscopy showed that MSN coating degraded outside the cells, releasing ZnONPs that interacted with cell membranes. MSN-ZnO-AuNSs efficiently reduced the viability of all cell lines, and CAL51/CALDOX cells were more susceptible than MCF7/MCF-7-TX cells. MSN-ZnO-AuNSs were then conjugated with the antibody to Frizzled-7 (FZD-7), the receptor upregulated by several breast cancer cells. We used the disulphide (S-S) linker that could be cleaved with a high concentration of glutathione normally observed within cancer cells, releasing Zn2+ into the cytoplasm. FZD-7 targeting resulted in approximately three-fold amplified toxicity of MSN-ZnO-AuNSs towards the MCF-7TX drug-resistant cell line with the highest FZD-7 expression. This study shows that ZnO-MSs are promising tools to treat triple-negative and drug-resistant breast cancers and highlights the potential clinical utility of FZD-7 for delivery of nanomedicines and imaging probes specifically to these cancer types.

Environmental pollution and toxic substances: Cellular apoptosis as a key parameter in a sensible model like fish

The industrial wastes, sewage effluents, agricultural run-off and decomposition of biological waste may cause high environmental concentration of chemicals that can interfere with the cell cycle activating the programmed process of cells death (apoptosis). In order to provide a detailed understanding of environmental pollutants-induced apoptosis, here we reviewed the current knowledge on the interactions of environmental chemicals and programmed cell death. Metals (aluminum, arsenic, cadmium, chromium, cobalt, zinc, copper, mercury and silver) as well as other chemicals including bleached kraft pulp mill effluent (BKME), persistent organic pollutants (POPs), and pesticides (organo-phosphated, organo-chlorinated, carbamates, phyretroids and biopesticides) were evaluated in relation to apoptotic pathways, heat shock proteins and metallothioneins. Although research performed over the past decades has improved our understanding of processes involved in apoptosis in fish, yet there is lack of knowledge on associations between environmental pollutants and apoptosis. Thus, this review could be useful tool to study the cytotoxic/apoptotic effects of different pollutants in fish species.

p53 and metabolism: from mechanism to therapeutics

The tumor cell changes itself and its microenvironment to adapt to different situations, including action of drugs and other agents targeting tumor control. Therefore, metabolism plays an important role in the activation of survival mechanisms to keep the cell proliferative potential. The Warburg effect directs the cellular metabolism towards an aerobic glycolytic pathway, despite the fact that it generates less adenosine triphosphate than oxidative phosphorylation; because it creates the building blocks necessary for cell proliferation. The transcription factor p53 is the master tumor suppressor; it binds to more than 4,000 sites in the genome and regulates the expression of more than 500 genes. Among these genes are important regulators of metabolism, affecting glucose, lipids and amino acids metabolism, oxidative phosphorylation, reactive oxygen species (ROS) generation and growth factors signaling. Wild-type and mutant p53 may have opposing effects in the expression of these metabolic genes. Therefore, depending on the p53 status of the cell, drugs that target metabolism may have different outcomes and metabolism may modulate drug resistance. Conversely, induction of p53 expression may regulate differently the tumor cell metabolism, inducing senescence, autophagy and apoptosis, which are dependent on the regulation of the PI3K/AKT/mTOR pathway and/or ROS induction. The interplay between p53 and metabolism is essential in the decision of cell fate and for cancer therapeutics.

The effect of "NutramilTM Complex," food for special medical purpose, on breast and prostate carcinoma cells

NutramilTM Complex is a multicomponent food product that meets the requirements of a food for special medical purpose. As a complete, high-energy diet it consists of properly balanced nutrients, vitamins and minerals. The aim of this study was to assess the effect of NutramilTM Complex on breast and prostate carcinoma cells. Our results showed that NutramilTM Complex reduced the viability and proliferation of breast and prostate cancer cells and that this process was associated with the induction of apoptosis via activation of caspase signalling. Data showed elevated levels of p53 tumour suppressor, up-regulation of p38 MAPK and SAPK / JNK proteins and downregulation of anti-apoptotic ERK1/2, AKT1 and HSP27. Treatment with NutramilTM Complex also affected the expression of the BCL2 family genes. Results also showed down-regulation of anti-apoptotic BCL-2 and up-regulation of pro-apoptotic members such as BAX, BAD, BID. In addition, we also observed regulation of many other genes, including Iκβα, Chk1 and Chk2, associated with apoptotic events. Taken together, our results suggest activation of the mitochondrial apoptotic pathway as most likely mechanism of anti-carcinogenic activity of NutramilTM Complex.

Anti-oxidant and anti-cancer activities of Angelica dahurica extract via induction of apoptosis in colon cancer cells

INTRODUCTION

Angelica dahurica Radix is the common herbal medicine with anti-cancer activities. However, details of its anti-cancer activities are lacking.

MATERIALS AND METHODS

We investigated the anti-cancer effects of Angelica dahurica extract in HT-29 colon cancer cell line. Cell viability, apoptotic and necrotic activities and the mechanism of actions of the active fraction were measured.

RESULTS AND DISCUSSION

The organic extract of Angelica dahurica Radi decreased significantly the gene expression of p53, Bcl, Bax and induced apoptosis via caspase cascade and cell cycle arrest. The ethanol-ethyl acetate fraction showed anti-cancer activities in HT-29 cancer cells. A HPLC-DAD analysis of the fraction indicated the presence of Imperatorin and isoimperatorin, which are the major coumarins in the active fraction that contribute to the anti-cancer activities.

CONCLUSIONS

This study has evaluated the ant-cancer activity of the organic extract of Angelica dahurica Radix against colon cancer cells and provided a basis of further development of the herbal extract for treatment of colon cancer.

Disruption of apoptosis pathways involved in zebrafish gonad differentiation by 17α-ethinylestradiol and fadrozole exposures

Zebrafish (Danio rerio) sex determination seems to involve genetic factors (GSD) but also environmental factors (ESD), such as endocrine disrupting chemicals (EDCs) that are known to mimic endogenous hormones and disrupt gonad differentiation. Apoptosis has also been proposed to play a crucial role in zebrafish gonad differentiation. Nevertheless, the interactions between EDCs and apoptosis have received little attention. Thus, this study aimed to assess if and which apoptotic pathways are involved in zebrafish gonad differentiation and how EDCs may interfere with this process. With these purposes, zebrafish were exposed to 17α-ethinylestradiol (EE2, 4ng/L) and fadrozole (Fad, 50μg/L) from 2h to 35days post-fertilization (dpf). Afterwards, a gene expression analysis by qRT-PCR and a stereological analysis, based on systematic sampling and protein immunohistochemistry, were performed. The death receptors (FAS; TRADD), anti-apoptotic (BCL-2; MDM2), pro-apoptotic (CASP-2 and -6) and cell proliferation (BIRC5/survivin; JUN) genes and proteins were evaluated. In general, apoptosis was inhibited in females through the involvement of anti-apoptotic pathways, while in males apoptosis seemed to be crucial to the failure of the "juvenile ovary" development and the induction of testes transformation. The JUN protein was shown to be necessary in juvenile ovaries, while the BIRC5 protein seemed to be involved in zebrafish spermatogenesis. Both EDCs, EE2 and Fad, increased the apoptosis stimulus in zebrafish gonad. It was noticed that the few females that were resistant to Fad-induced sex reversal had increased anti-apoptotic factor levels, while males exposed to EE2 showed increased pro-apoptotic genes/proteins and were more advanced in gonad differentiation. Overall, our findings show that apoptosis pathways are involved in zebrafish gonad differentiation and that EDCs can disrupt this process.

Copper induced apoptosis in Caco-2 and Hep-G2 cells: Expression of caspases 3, 8 and 9, AIF and p53

Copper (Cu) is an essential trace metal needed to ensure cell function. However, when present at high concentrations it becomes toxic to organisms. Cell death, induced by toxic levels of copper, was previously observed in in vitro studies. However, there is no consensus about the cell death pathway induced by Cu and it is still not known whether this occurs as a result of the direct action of the metal or by indirect effects. In the present work, we intend to identify the influence of different Cu concentrations in the induction of apoptosis and to explore the potential signaling pathways, using two different in vitro cell culture models (Caco-2 and Hep-G2). Cells were exposed, during 6, 12, 24 and 48h, to Cu concentrations corresponding to IC50 and 1/8 of IC50, according to the viability assays. Then, considering the different apoptosis pathways, the expression of caspases 3, 8 and 9, apoptosis inducing factor (AIF) and p53 genes was analyzed by quantitative real time PCR. The results suggested that different Cu concentrations could trigger different apoptotic pathways, at different times of exposure. In both cell lines, apoptosis seems to be initiated by caspase independent pathway and intrinsic pathway, followed by extrinsic pathway. In conclusion, this study demonstrates that Cu induces the activation of apoptosis through caspase dependent and independent pathways, also suggesting that apoptosis activation mechanism is dependent on the concentration, time of exposure to Cu and cell type.

Anticancer effects of synthetic hexahydrobenzo [g]chromen-4-one derivatives on human breast cancer cell lines

BACKGROUND

Cancer results from a series of molecular changes that alter the normal function of cells. Breast cancer is the second leading cause of cancer death in women. To develop novel anticancer agents, new series of chromen derivatives were synthesized and evaluated for their cytotoxic activity against human breast cancer cell lines.

METHOD

The growth inhibitory activities of synthesized hexahydrobenzo chromen-4-one were screened against six human cancer cell lines using an in vitro cell culture system (MTT assay). Fluorochrome staining (acridine orange/ethidium bromide double staining) and DNA fragmentation by the diphenylamine method were used to investigate the effects of most potent compounds on the process of apoptosis in breast cancer cell lines. To determine the mechanism of apoptosis, ROS and NOX production in treated breast cancer cells with compounds was evaluated.

RESULTS

The cytotoxicity data of tested compounds demonstrate these compounds had varying degree of toxicity. Compound 7h was the most potent compound with IC₅₀ = 1.8 ± 0.6 µg/mL against T-47D cell line. Analyses of the compounds treated (MCF-7, MDA-MB-231, and T-47D) cells by acridine orange/ethidium bromide double staining and DNA fragmentation by the diphenylamine method showed that the synthetic compounds induce apoptosis in the cells. A significant increase in ROS production was observed in T-47D cells treated with IC₅₀ value of compound 7g. Incubation with IC₅₀ value of synthetic compounds increased the NOX production in cell lines, especially T-47D cells.

CONCLUSION

Our results show that most compounds have a significant anti-proliferative activity against six human cancer cell lines. The observations confirm that chromen derivatives have induced the cell death through apoptosis.

p53 Loss in MYC-Driven Neuroblastoma Leads to Metabolic Adaptations Supporting Radioresistance

Neuroblastoma is the most common childhood extracranial solid tumor. In high-risk cases, many of which are characterized by amplification of MYCN, outcome remains poor. Mutations in the p53 (TP53) tumor suppressor are rare at diagnosis, but evidence suggests that p53 function is often impaired in relapsed, treatment-resistant disease. To address the role of p53 loss of function in the development and pathogenesis of high-risk neuroblastoma, we generated a MYCN-driven genetically engineered mouse model in which the tamoxifen-inducible p53ER(TAM) fusion protein was expressed from a knock-in allele (Th-MYCN/Trp53(KI)). We observed no significant differences in tumor-free survival between Th-MYCN mice heterozygous for Trp53(KI) (n = 188) and Th-MYCN mice with wild-type p53 (n = 101). Conversely, the survival of Th-MYCN/Trp53(KI/KI) mice lacking functional p53 (n = 60) was greatly reduced. We found that Th-MYCN/Trp53(KI/KI) tumors were resistant to ionizing radiation (IR), as expected. However, restoration of functional p53ER(TAM) reinstated sensitivity to IR in only 50% of Th-MYCN/Trp53(KI/KI) tumors, indicating the acquisition of additional resistance mechanisms. Gene expression and metabolic analyses indicated that the principal acquired mechanism of resistance to IR in the absence of functional p53 was metabolic adaptation in response to chronic oxidative stress. Tumors exhibited increased antioxidant metabolites and upregulation of glutathione S-transferase pathway genes, including Gstp1 and Gstz1, which are associated with poor outcome in human neuroblastoma. Accordingly, glutathione depletion by buthionine sulfoximine together with restoration of p53 activity resensitized tumors to IR. Our findings highlight the complex pathways operating in relapsed neuroblastomas and the need for combination therapies that target the diverse resistance mechanisms at play. Cancer Res; 76(10); 3025-35. ©2016 AACR.

Basal and copper-induced expression of metallothionein isoform 1,2 and 3 genes in epithelial cancer cells: The role of tumor suppressor p53

Metallothioneins (MTs) are a ubiquitous low-molecular weight, cysteine rich proteins with a high affinity for metal ions. The expression and induction of MTs have been associated with protection against DNA damage, oxidative stress, and apoptosis. Our past research had shown that p53 is an important factor in metal regulation of MTs. The present study was undertaken to explore further the interrelationship between p53 and MTs. We investigated whether silencing of p53 could affect expression pattern of basal and copper induced metallothioneins. The silencing of wild-type p53 (wt-p53) in epithelial breast cancer MCF7 cells affected the basal level of MT-2A RNA, whereas the levels of MT-1A and MT-1X RNA remained largely unchanged. The expression of MT-3 was undetectable in MCF7 with either functional or silenced p53. MCF7 cells with silenced wt-p53 failed to upregulate MT-2A in response to copper and showed a reduced sensitivity toward copper induced cell apoptotic death. Similarly in MCF7-E6 and MDA-MB-231 cells, the presence of inactive/mutated p53 halted MT-1A and MT-2A gene expression in response to copper. Constitutive expression of MT-3 RNA was detectable in the presence of mutated p53 (mtp53). Transient transfection of MDA-MB-231 cells with wt-p53 enabled copper induced upregulation of both MT-1A and MT-2A but not basal level of MT-2A, MT-1E, MT-1X and MT-3. Inactivation of p53 in HepG2 cells amplified the basal expression of studied MT isoforms, including MT-3, as well as copper-induced mRNA expression of MTs except MT-1H and MT-3. Presented data demonstrate a direct relation between p53 and MT-1A and MT-2A and they also indicate that wt-p53 might be a negative regulator of MT-3 in epithelial cancer cells.

In situ clinical evidence that zinc levels are decreased in breast invasive ductal carcinoma

PURPOSE

Altered zinc levels in malignant cells versus their normal cells have important implications in the development and progression of several cancers. Prostate, pancreatic, and hepatocellular carcinomas exhibit consistent marked zinc decrease in situ in the malignant cells, and other cancers (such as kidney, lung, and thyroid) also exhibit decreased tissue zinc levels. However, zinc levels are increased in breast cancer tissue compared to breast normal tissue, and the contemporary dominant view is that zinc is increased in invasive ductal carcinoma. This has important implications regarding the role and effects of zinc in breast malignancy compared to other cancers, which caused us to initiate this study to either confirm or challenge the contemporary view of an increased zinc level in the invasive ductal malignant cells.

METHODS

We employed dithizone staining of breast tissue sections and tissue cores to determine the relative in situ cellular zinc levels specifically in the invasive ductal malignant cells as compared to normal ductal epithelium. This approach had not been employed in any of the reported breast studies.

RESULTS

The results revealed that the zinc levels are consistently and markedly decreased in the ductal malignant cells as compared with higher prominent zinc levels in the normal ductal epithelium. Decreased zinc is evident in Grade 1 well-differentiated malignancy and in Grade 2 and Grade 3 carcinomas. Among the twenty-five cancer cases in this study, none exhibited increased zinc in the invasive ductal carcinoma compared to the zinc level in the normal ductal epithelium.

CONCLUSIONS

The decreased zinc levels in breast invasive ductal carcinoma is consistent with prostate, pancreatic, and liver carcinomas in which the decrease in zinc is a required event in the development of malignancy to prevent cytotoxicity that would result from the higher zinc levels in the normal cells. This new understanding requires a redirection in elucidating the mechanisms and factors regarding the regulation of zinc in breast cancer, its potential translational applications as possible biomarkers, and for treatment of breast invasive ductal carcinoma.

Midline2 is overexpressed and a prognostic indicator in human breast cancer and promotes breast cancer cell proliferation in vitro and in vivo

Midline2 (MID2) is an ubiquitin-conjugating E2 enzyme linked to tumor progression and a novel interacting partner of breast cancer 1, early-onset (BRCA1). However, the role of MID2 in breast cancer remains unknown. This study investigated the expression, prognostic value, and role of MID2 in breast cancer. The expression of MID2 mRNA and protein was significantly upregulated in breast cancer tissue and established cell lines compared with that in normal breast epithelial cells and paired adjacent non-tumor tissue (P < 0.001). Immunohistochemical analysis demonstrated that MID2 was overexpressed in 272 of 284 (95.8%) paraffinembedded, archived breast cancer tissue. Moreover, MID2 expression increased with advanced clinical stage (P < 0.001). High MID2 expression was significantly associated with advanced clinical stages and T, N, and M staging (all P < 0.05). Univariate and multivariate analyses indicated that high MID2 expression was an independent prognostic factor for poor overall survival in the entire cohort (93.73 vs. 172.1 months; P < 0.001, logrank test) and in subgroups with stages Tis + I + II and III + IV. Furthermore, 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide colony formation, and anchorage-independent growth ability assays were conducted. Results showed that siRNA silencing of MID2 expression significantly reduced MCF-7 and MDA-MB-231 cell proliferation in vitro and blocked the growth of MDA-MB-231 cell xenograft tumors in vivo (P < 0.05). This study indicated that MID2 may be a novel prognostic marker and interventional target in breast cancer.

Oxidative damage induced by copper in mouse primary hepatocytes by single-cell analysis

Copper can disturb the intracellular redox balance, induce oxidative stress, and subsequently cause irreversible damage, leading to a variety of diseases. In the present study, mouse primary hepatocytes were chosen to elucidate the in vitro oxidative damage of short-term copper exposure (10-200 μM) by single-cell analysis. We evaluated the toxicity of copper by reactive oxygen species (ROS), glutathione (GSH), and oxidative DNA damage at the single-cell level. Oxidative damage induced by copper was verified by the morphological changes, persistent elevations of excessive ROS and malondialdehyde (MDA), a decrease in GSH level, and the oxidative DNA damage. Furthermore, the average ROS generation, GSH consumption, and the indicators in DNA damage did not significantly change at relatively low concentrations (10 or 50 μM), but we can find the alterations of parameters in some single cells clearly. Emphasis on the analysis of single cells is conducive to gain a better understanding on the toxicity of copper. This study will also complement studies on the environmental risk assessment of copper pollution.

Assessing the carcinogenic potential of low-dose exposures to chemical mixtures in the environment: the challenge ahead

Low-dose exposures to common environmental chemicals that are deemed safe individually may be combining to instigate carcinogenesis, thereby contributing to the incidence of cancer. This risk may be overlooked by current regulatory practices and needs to be vigorously investigated.

Lifestyle factors are responsible for a considerable portion of cancer incidence worldwide, but credible estimates from the World Health Organization and the International Agency for Research on Cancer (IARC) suggest that the fraction of cancers attributable to toxic environmental exposures is between 7% and 19%. To explore the hypothesis that low-dose exposures to mixtures of chemicals in the environment may be combining to contribute to environmental carcinogenesis, we reviewed 11 hallmark phenotypes of cancer, multiple priority target sites for disruption in each area and prototypical chemical disruptors for all targets, this included dose-response characterizations, evidence of low-dose effects and cross-hallmark effects for all targets and chemicals. In total, 85 examples of chemicals were reviewed for actions on key pathways/mechanisms related to carcinogenesis. Only 15% (13/85) were found to have evidence of a dose-response threshold, whereas 59% (50/85) exerted low-dose effects. No dose-response information was found for the remaining 26% (22/85). Our analysis suggests that the cumulative effects of individual (non-carcinogenic) chemicals acting on different pathways, and a variety of related systems, organs, tissues and cells could plausibly conspire to produce carcinogenic synergies. Additional basic research on carcinogenesis and research focused on low-dose effects of chemical mixtures needs to be rigorously pursued before the merits of this hypothesis can be further advanced. However, the structure of the World Health Organization International Programme on Chemical Safety ‘Mode of Action’ framework should be revisited as it has inherent weaknesses that are not fully aligned with our current understanding of cancer biology.

Zinc supplementation induces apoptosis and enhances antitumor efficacy of docetaxel in non-small-cell lung cancer

BACKGROUND

Exposure to exogenous zinc results in increased apoptosis, growth inhibition, and altered oxidative stress in cancer cells. Previous studies also suggested that zinc sensitizes some cancer cells to cytotoxic agents depending on the p53 status. Therefore, zinc supplementation may show anticancer efficacy solely and may increase docetaxel-induced cytotoxicity in non-small-cell lung cancer cells.

METHODS

Here, we report the effects of several concentrations of zinc combined with docetaxel on p53-wild-type (A549) and p53-null (H1299) cells. We evaluated cellular viability, apoptosis, and cell cycle progression as well as oxidative stress parameters, including superoxide dismutase, glutathione peroxidase, and malondialdehyde levels.

RESULTS

Zinc reduced the viability of A549 cells and increased the apoptotic response in both cell lines in a dose-dependent manner. Zinc also amplified the docetaxel effects and reduced its inhibitory concentration 50 (IC50) values. The superoxide dismutase levels increased in all treatment groups; however, glutathione peroxidase was slightly increased in the combination treatments. Zinc also caused malondialdehyde elevations at 50 μM and 100 μM.

CONCLUSION

Zinc has anticancer efficacy against non-small-cell lung cancer cells in the presence of functionally active p53 and enhances docetaxel efficacy in both p53-wild-type and p53-deficient cancer cells.

Comparative assessment of the apoptotic potential of silver nanoparticles synthesized by Bacillus tequilensis and Calocybe indica in MDA-MB-231 human breast cancer cells: targeting p53 for anticancer therapy

Background

Recently, the use of nanotechnology has been expanding very rapidly in diverse areas of research, such as consumer products, energy, materials, and medicine. This is especially true in the area of nanomedicine, due to physicochemical properties, such as mechanical, chemical, magnetic, optical, and electrical properties, compared with bulk materials. The first goal of this study was to produce silver nanoparticles (AgNPs) using two different biological resources as reducing agents, Bacillus tequilensis and Calocybe indica. The second goal was to investigate the apoptotic potential of the as-prepared AgNPs in breast cancer cells. The final goal was to investigate the role of p53 in the cellular response elicited by AgNPs.

Methods

The synthesis and characterization of AgNPs were assessed by various analytical techniques, including ultraviolet-visible (UV-vis) spectroscopy, X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, dynamic light scattering (DLS), and transmission electron microscopy (TEM). The apoptotic efficiency of AgNPs was confirmed using a series of assays, including cell viability, leakage of lactate dehydrogenase (LDH), production of reactive oxygen species (ROS), DNA fragmentation, mitochondrial membrane potential, and Western blot.

Results

The absorption spectrum of the yellow AgNPs showed the presence of nanoparticles. XRD and FTIR spectroscopy results confirmed the crystal structure and biomolecules involved in the synthesis of AgNPs. The AgNPs derived from bacteria and fungi showed distinguishable shapes, with an average size of 20 nm. Cell viability assays suggested a dose-dependent toxic effect of AgNPs, which was confirmed by leakage of LDH, activation of ROS, and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL)-positive cells in MDA-MB-231 breast cancer cells. Western blot analyses revealed that AgNPs induce cellular apoptosis via activation of p53, p-Erk1/2, and caspase-3 signaling, and downregulation of Bcl-2. Cells pretreated with pifithrin-alpha were protected from p53-mediated AgNPs-induced toxicity.

Conclusion

We have demonstrated a simple approach for the synthesis of AgNPs using the novel strains B. tequilensis and C. indica, as well as their mechanism of cell death in a p53-dependent manner in MDA-MB-231 human breast cancer cells. The present findings could provide insight for the future development of a suitable anticancer drug, which may lead to the development of novel nanotherapeutic molecules for the treatment of cancers.

Metal toxicity and the p53 protein: an intimate relationship

The relationship between p53, ROS and transition metals.

The role of NOS-mediated ROS accumulation in an early phase Cu-induced acute cytotoxicity in MCF-7 cells

Copper (Cu) ion is essential for the biological systems, however, high level of CuCl2 exposure causes detrimental effects, which leads to cell apoptosis. Nitric oxide (NO) is an efficient cell signal messenger, which plays an important role in cell apoptosis. However, the potential mechanism of an early phase Cu-induced acute cytotoxicity through the nitric oxide synthase (NOS) signaling pathway and its interaction has not been studied. In this report, we provide data showing that high level of CuCl2 could rapidly decrease the NO production with the release of Ca(2+) and Zn(2+), and then modulate the transcriptional and translational expression of NOSs in MCF-7 cells. The reactive oxygen species (ROS) level in cells was increased after high level of CuCl2 exposure, which led to the alpha subunit of eukaryotic initiation factor 2 phosphorylation. By using the free radical scavenger N-acetyl-L-cysteine or the NOS substrate L-arginine, it demonstrated that NOS played a critical role on the Cu-induced ROS generation, which further led to the oxidative stress and cell apoptosis. These results suggested that Cu-induced apoptosis was associated with the oxidative stress, and through the NOS-mediated signaling pathway.

The role of nitric oxide synthase signaling pathway in the Zn-induced cellular responses in MCF-7 cells

Trace amount zinc plays key roles in biological systems, while in excessive amount it causes toxic effects. Evidence shows that there exists a crosstalk between NO and Zn apoptotic signal transduction pathway. However, the potential mechanism of Zn-induced cellular responses through the NOS signaling pathway has not been determined yet. In this research, trace amount ZnCl2 (1nM) could induce the NO production, however it appears that this influence does not extend to genetic level in MCF-7 cells. Whereas, excess ZnCl2 (100μM, 1mM) could lead to a decreased NO production first with the release of Ca(2+), and then induce the NO production with the transcriptional and translational activation of NOSs. The ROS generation was also induced by excess ZnCl2, causing the elF2α phosphorylation. The alleviation effect of N-acetyl-l-cysteine or l-arginine on the Zn-induced ROS generation and apoptosis suggested that Zn-induced apoptosis was associated with the NOS-mediated oxidative stress.

Anti-proliferative activities of sinigrin on carcinogen-induced hepatotoxicity in rats

Liver cancer is one of the leading causes of cancer death worldwide. A very high incidence of new liver cancer cases is diagnosed every year, and metastasis has been found to correlate to poor prognoses in humans. Better treatments for liver cancer are thus clearly needed. Sinigrin is one of the major ingredients present in Brassica nigra, which has been used in combination with other herbs for treatment of various diseases. The anti-proliferative activities of sinigrin were studied in a model of carcinogen-induced hepatotoxicity in rats. Rats were orally administered with sinigrin on a daily basis for three months before sacrifice. Sinigrin was found to significantly inhibit the proliferation of liver tumor cells; the number of surface tumors in the rat liver was dramatically reduced. Sinigrin induced apoptosis of liver cancer cells through up-regulation of p53 and down-regulation of Bcl-2 family members and caspases. Our findings indicated that the liver functions were gradually restored after treatment with sinigrin and that the agent did not cause liver toxicity. Cell cycle analysis indicated that sinigrin caused cell cycle arrest in G0/G1 phase. The results suggest that sinigrin exerts important anti-proliferative activities in carcinogen-induced hepatocarcinogenesis in rats, and highlight the potential of sinigrin as an anti-cancer agent for liver cancer.

Pyrostegia venusta heptane extract containing saturated aliphatic hydrocarbons induces apoptosis on B16F10-Nex2 melanoma cells and displays antitumor activity in vivo

Background:

Pyrostegia venusta (Ker. Gawl.) Miers (Bignoniacea) is a medicinal plant from the Brazilian Cerrado used to treat leucoderma and common diseases of the respiratory system.

Objective:

To investigate the antitumor activity of P.venusta extracts against melanoma.

Materials and Methods:

The cytotoxic activity and tumor induced cell death of heptane extract (HE) from P. venusta flowers was evaluated against murine melanoma B16F10-Nex2 cells in vitro and in a syngeneic model in vivo.

Results:

We found that HE induced apoptosis in melanoma cells by disruption of the mitochondrial membrane potential, induction of reactive oxygen species and late apoptosis evidenced by plasma membrane blebbing, cell shrinkage, chromatin condensation and DNA fragmentation, exposure of phosphatidylserine on the cell surface and activation of caspase-2,-3,-8,-9. HE was also protective against singeneyc subcutaneous melanoma HE compounds were also able to induce cell cycle arrest at G2/M phases on tumor cells. On fractionation of HE in silica gel we isolated a cytotoxic fraction that contained a mixture of saturated hydrocarbons identified by ¹H NMR and GC-MS analyses. Predominant species were octacosane (C₂₈H₅₈-36%) and triacontane (C₃₀H₆₂-13%), which individually showed significant cytotoxic activity against murine melanoma B16F10-Nex2 cells in vitro and a very promising antitumor protection against subcutaneous melanoma in vivo.

Conclusion:

The results suggest that the components of the heptane extract, mainly octasane and triacontane, which showed antitumor properties in experimental melanoma upon regional administration, might also be therapeutic in human cancer, such as in the mostly epidermal and slowly invasive melanomas, such as acral lentiginous melanoma, as an adjuvant treatment to surgical excision.

Differential responses of neuronal and spermatogenic cells to the doppel cytotoxicity

Although structurally and biochemically similar to the cellular prion (PrP(C)), doppel (Dpl) is unique in its biological functions. There are no reports about any neurodegenerative diseases induced by Dpl. However the artificial expression of Dpl in the PrP-deficient mouse brain causes ataxia with Purkinje cell death. Abundant Dpl proteins have been found in testis and depletion of the Dpl gene (Prnd) causes male infertility. Therefore, we hypothesize different regulations of Prnd in the nerve and male productive systems. In this study, by electrophoretic mobility shift assays we have determined that two different sets of transcription factors are involved in regulation of the Prnd promoter in mouse neuronal N2a and GC-1 spermatogenic (spg) cells, i.e., upstream stimulatory factors (USF) in both cells, Brn-3 and Sp1 in GC-1 spg cells, and Sp3 in N2a cells, leading to the expression of Dpl in GC-1 spg but not in N2a cells. We have further defined that, in N2a cells, Dpl induces oxidative stress and apoptosis, which stimulate ataxia-telangiectasia mutated (ATM)-modulating bindings of transcription factors, p53 and p21, to Prnp promoter, resulting the PrP(C) elevation for counteraction of the Dpl cytotoxicity; in contrast, in GC-1 spg cells, phosphorylation of p21 and N-terminal truncated PrP may play roles in the control of Dpl-induced apoptosis, which may benefit the physiological function of Dpl in the male reproduction system.

Marijuana smoke condensate induces p53-mediated apoptosis in human lung epithelial cells

Since the largely abused worldwide used of marijuana, there have been many ongoing debates regarding the adverse health effects of marijuana smoking. Marijuana smoking was recently proved to cause pulmonary toxicity by inducing genotoxic effects or generating reactive oxygen species. Because p53, a tumor suppressor gene, has an important pathophysiologic role in the regulation of lung epithelial cell DNA damage responses, we hypothesized that p53 may be involved in the oxidative stress-mediated apoptosis induced by marijuana smoking. First, we confirmed that marijuana smoke condensate (MSC) induces oxidative stress in BEAS-2B cells. We observed that reactive oxygen species (ROS) generation was increased by MSC in the DCFH-DA assay. Also, antioxidant enzyme (superoxide dismutase, catalase) activity and their mRNA expressions were up-regulated by MSC. Second, we investigated p53 involvement in the MSC-induced apoptotic pathway in BEAS-2B cells. The results showed that MSC increased caspase-3 activation and DNA fragmentation as markers of apoptosis. In addition, the mRNA levels of apoptosis-related genes (p53 and Bax) were increased by MSC and phospho-p53, along with the increase of Bax protein expression by MSC. Apoptosis and apoptosis-related gene expression were partially blocked by an inhibitor of p53-dependent transcriptional activation (pifithrin-α). The results indicate that p53 plays a role in MSC-induced apoptosis. Taken together, the findings of the present study suggest that MSC partially induces p53-mediated apoptosis through ROS generation in human lung epithelial cells and this may have broader implications for our understanding of pulmonary diseases.

Solute carriers (SLCs) in cancer

During tumor progression cells acquire an altered metabolism, either as a cause or as a consequence of an increased need of energy and nutrients. All four major classes of macromolecules are affected: carbohydrates, proteins, lipids and nucleic acids. As a result of the changed needs, solute carriers (SLCs) which are the major transporters of these molecules are differently expressed. This renders them important targets in the treatment of cancer. Blocking or activating SLCs is one possible therapeutic strategy. For example, some SLCs are upregulated in tumor cells due to the increased demand for energy and nutritional needs. Thus, blocking them and turning off the delivery of fuel or nutrients could be one way to interfere with tumor progression. Specific drug delivery to cancer cells via transporters is another approach. Some SLCs are also interesting as chemosensitizing targets because blocking or activating them may result in an altered response to chemotherapy. In this review we summarize the roles of SLCs in cancer therapy and specifically their potential as direct or indirect targets, as drug carriers or as chemosensitizing targets.

Copper induces apoptotic cell death through reactive oxygen species-triggered oxidative stress in the intertidal copepod Tigriopus japonicus

The copepod, Tigriopus japonicus is an important model for toxicity testing. However, no attempt has been made in analyzing the effect of toxicants at the level of the ROS-mediated signal transduction pathway. To understand copper-induced cytotoxicity at the molecular level, we employed several cellular and biochemical assays after exposure to copper, and found a significant induction of enzyme activities of antioxidant proteins with increased intracellular reactive oxygen species (ROS) as well as an increase of TUNEL-positive cells, but a decrease of BrdU-positive cells. In addition, several important genes such as p38 MAPK, antioxidant-related genes, Hsps, and apoptosis-related genes were significantly modulated by copper exposure. Taken together, we suggest that copper-induced cytotoxicity is mediated by the formation of intracellular ROS and oxidative stress in T. japonicus. Whole body biochemical assays such as TUNEL- and BrdU-assay will provide a better understanding of cellular responses such as apoptosis and cell death upon cytotoxic exposure of copper in T. japonicus.

Copper induced upregulation of apoptosis related genes in zebrafish (Danio rerio) gill

Copper (Cu) is an essential micronutrient that, when present in high concentrations, becomes toxic to aquatic organisms. It is known that Cu toxicity may induce apoptotic cell death. However, the precise mechanism and the pathways that are activated, in fish, are still unclear. Thus, this study aimed to assess which apoptotic pathways are triggered by Cu, in zebrafish (Danio rerio) gill, the main target of waterborne pollutants. Fish where exposed to 12.5 and 100 μg/L of Cu during 6, 12, 24 and 48 h. Fish gills were collected to TUNEL assay and mRNA expression analysis of selected genes by real time PCR. An approach to different apoptosis pathways was done selecting p53, caspase-8, caspase-9 and apoptosis inducing factor (AIF) genes. The higher incidence of TUNEL-positive cells, in gill epithelia of the exposed fish, proved that Cu induced apoptosis. The results suggest that different apoptosis pathways are triggered by Cu at different time points of the exposure period, as the increase in transcripts was sequential, instead of simultaneous. Apoptosis seems to be initiated via intrinsic pathway (caspase-9), through p53 activation; then followed by the extrinsic pathway (caspase-8) and finally by the caspase-independent pathway (AIF). A possible model for Cu-induce apoptosis pathways is proposed.

The effect of zinc and the role of p53 in copper-induced cellular stress responses

Metals can directly or indirectly cause an increase in reactive oxygen species (ROS) accumulation in cells, and this may result in programmed cell death. A number of previous studies have shown that zinc (Zn) modulates mitogenic activity via several signalling pathways, such as AKT, mitogen-activated protein kinase (MAPK), nuclear factor-kappa B (NF -κB), AP-1 and p53. The exact role that Zn plays in the regulation of apoptosis remains ambiguous. Intracellular free Zn modulates p53 activity and stability, and excess Zn alters the p53 protein structure and down-regulates p53's binding to DNA. Copper (Cu) accumulation causes apoptosis that seems to be mediated by DNA damage and subsequent p53 activation. Cu can also displace Zn from its normal binding site on p53, resulting in abnormal protein folding and disruption of p53 function. In spite of the induction of the tumour suppressor p53, hepatic Cu accumulation significantly increases the risk of cancerous neoplasm both in humans and rats, suggesting that p53 function may be impaired in these cells. It is generally understood that imbalances in Cu and Zn levels may lead to a higher prevalence of p53 mutations. An increased number of p53 mutations have been found in liver samples from Wilson's disease (WD) patients. High levels of the p53 mutation most probably contribute to the pathogenesis of cancer in individuals with WD, but the cause and effect are not clear. The protein p53 also plays a crucial role in the transcriptional regulation of metallothionein, which indicates a novel regulatory role for p53. This review discusses the central role of p53 and the redox-inert metal Zn in the cellular stress responses induced by the redox active biometal Cu.

Effects of shear stresses and antioxidant concentrations on the production of reactive oxygen species in lung cancer cells

Reactive oxygen species (ROS) are known to be a key factor in the development of cancer, and many exogenous sources are supposed to be related to the formation of ROS. In this paper, a microfluidic chip was developed for studying the production of ROS in lung cancer cells under different chemical and physical stimuli. This chip has two unique features: (1) five relative concentrations of 0, 1/8, 1/2, 7/8, and 1 are achieved in the culture regions; (2) a shear stress gradient is produced inside each of the five culture areas. Lung cancer cells were seeded inside this biocompatible chip for investigating their response to different concentrations of H2O2, a chemical stimulus known to increase the production of ROS. Then the effect of shear stress, a physical stimulus, on lung cancer cells was examined, showing that the production of ROS was increased in response to a larger shear stress. Finally, two antioxidants, α-tocopherol and ferulic acid, were used to study their effects on reducing ROS. It was found that high-dose α-tocopherol was not able to effectively eliminate the ROS produced inside cells. This counter effect was not observed in cells cultured in a traditional chamber slide, where no shear stress was present. This result suggests that the current microfluidic chip provides an in vitro platform best mimicking the physiological condition where cells are under circulating conditions.

Functional repeats (TGYCC)n in the p53-inducible gene 3 (PIG3) promoter and susceptibility to squamous cell carcinoma of the head and neck

A polymorphic pentanucleotide microsatellite sequence (TGYCC)n within the p53-inducible gene 3 (PIG3) promoter is correlated with the extent of transcriptional activation by p53 and thought to modulate susceptibility to cancer. Using a PCR-silver staining-based single-strand conformation assay, we visualized variant genotypes of the PIG3 promoter (TGYCC)n motif in a subset of 100 subjects for each of four ethnic groups: non-Hispanic whites, African Americans, Hispanic Americans and Native Chinese. We found that PIG3 (TGYCC)15 was the most common allele but less frequent in non-Hispanic whites (0.660) than in Chinese (0.785) (P = 0.016). In an additional study of 616 patients with squamous cell carcinoma of the head and neck (SCCHN) and 623 cancer-free controls in a non-Hispanic white population, we found that compared with those who were PIG3 (TGYCC)15 homozygotes, subjects without the PIG3 (TGYCC)15 allele had a significantly increased SCCHN risk [adjusted odds ratio (OR) = 1.34; 95% CI = 1.04-1.73 for heterozygotes and OR = 1.69; 95% CI = 1.18-2.44 for variant homozygotes] in an allele-dose response manner (P = 0.002). Consistently, subsequent luciferase reporter assay revealed that the wild-type (TGYCC)15 allele had the highest p53-mediated transcriptional activity, compared with the other (TGYCC)n motifs. Our data suggest that the PIG3 variant polymorphic repeats alleles other than (TGYCC)15 may affect p53 binding and thus may be a marker for susceptibility to SCCHN, but our findings need to be validated in larger studies.

The Role of p53 in Marijuana Smoke Condensates-induced Genotoxicity and Apoptosis

OBJECTIVES

Marijuana is one of the most frequently abused drug in Korea and its adverse health effects are controversial. p53 is known to be crucial in regulating the DNA damage responses, and adverse effects can occur when it is regulated by marijuana smoke. We evaluated a role of p53 on genotoxic effect and apoptosis in lung cancer cells exposed to marijuana smoke condensates (MSCs).

METHODS

The p53-related genotoxicity and apoptosis of MSCs were evaluated using in vitro bioassay, viz., comet assay, cytokinesis-block micronucleus assay and apoptosis assay. We used two cell lines with differential p53 expression (p53-wildtype (WT) H460 and p53-null H1299).

RESULTS

MSCs significantly increased DNA breakages and chromosomal changes in p53-WT H460 and p53-null H1299 cells. The genotoxicity induced by MSCs in p53-null H1299 cells showed greater sensitivity than p53-WT H460 cells. Moreover, MSCs showed a significant increase in reactive oxygen species production and apoptosis. The apoptotic responses induced by MSCs were higher in p53-WT H460 cells than in p53-null H1299 cells. Significantly increased mRNA expression or apoptosis related genes, including p53, caspase-3, and Bax/Bcl-2 ratio were observed in the p53-WT H460 cells exposed to MSCs.

CONCLUSIONS

These results suggest that MSCs induce DNA/chromosomal damages and apoptosis in human lung cancer cells and p53 plays an important role in the cellular response to MSCs. The present study may have border implications for our understanding of pulmonary diseases.

Cellular mechanisms of zinc dysregulation: a perspective on zinc homeostasis as an etiological factor in the development and progression of breast cancer

Worldwide, breast cancer is the most commonly diagnosed cancer among women and is the leading cause of female cancer deaths. Zinc (Zn) functions as an antioxidant and plays a role in maintaining genomic stability. Zn deficiency results in oxidative DNA damage and increased cancer risk. Studies suggest an inverse association between dietary and plasma Zn levels and the risk for developing breast cancer. In contrast, breast tumor biopsies display significantly higher Zn levels compared with normal tissue. Zn accumulation in tumor tissue also correlates with increased levels of Zn importing proteins. Further, aberrant expression of Zn transporters in tumors correlates with malignancy, suggesting that altered metal homeostasis in the breast could contribute to malignant transformation and the severity of cancer. However, studies have yet to link dysregulated Zn transport and abnormal Zn-dependent functions in breast cancer development. Herein, we summarize studies that address the multi-modal role of Zn dyshomeostasis in breast cancer with respect to the role of Zn in modulating oxidative stress, DNA damage response/repair pathways and cell proliferation/apoptosis, and the relationship to aberrant regulation of Zn transporters. We also compare Zn dysregulation in breast tissue to that of prostate, pancreatic and ovarian cancer where possible.

Mammalian metallothioneins: properties and functions

Metallothioneins (MT) are a family of ubiquitous proteins, whose role is still discussed in numerous papers, but their affinity to some metal ions is undisputable. These cysteine-rich proteins are connected with antioxidant activity and protective effects on biomolecules against free radicals, especially reactive oxygen species. In this review, the connection between zinc(II) ions, reactive oxygen species, heavy metal ions and metallothioneins is demonstrated with respect to effect of these proteins on cell proliferation and a possible negative role in resistance to heavy metal-based and non-heavy metal-based drugs.

Redox regulation of p53, redox effectors regulated by p53: a subtle balance

SIGNIFICANCE

Reactive oxygen species (ROS), generated by cells as side products of biological reactions, function as secondary messengers by impacting a host of cellular networks involved in maintaining normal homeostatic growth as well as pathological disease states. Redox-sensitive proteins, such as the tumor suppressor protein p53, are susceptible to ROS-dependent modifications, which could impact their activities and/or biological functions.

RECENT ADVANCES

p53 is a transcription factor that controls a wide variety of target genes and regulates numerous cellular functions in response to stresses that lead to genomic instability. Thus, redox modifications of p53 could impact cell fate signaling and could have profound effects on pathways fundamental to maintaining cell and tissue integrity.

CRITICAL ISSUES

Recent studies present evidence that ROS function upstream of p53 in some model systems, while in others ROS production could be a downstream effect of p53 activation.

FUTURE DIRECTIONS

In this review, we describe how ROS production regulates p53 activity and how p53 can, in turn, influence cellular ROS production.