Mitochondrial dynamic alterations regulate melanoma cell progression.

Research on mitochondrial fusion and fission (mitochondrial dynamics) has gained much attention in recent years, as it is important for understanding many biological processes, including the maintenance of mitochondrial functions, apoptosis, and cancer. The rate of mitochondrial biosynthesis and degradation can affect various aspects of tumor progression. However, the role of mitochondrial dynamics in melanoma progression remains controversial and requires a mechanistic understanding to target the altered metabolism of cancer cells. Therefore, in our study, we disrupted mitochondrial fission with mdivi-1, the reported inhibitor of dynamin related protein 1 (Drp1), and knocked down Drp1 and Mfn2 to evaluate the effects of mitochondrial dynamic alterations on melanoma cell progression. Our confocal study results showed that mitochondrial fission was inhibited both in mdivi-1 and in Drp1 knockdown cells and, in parallel, mitochondrial fusion was induced. We also found that mitochondrial fission inhibition by mdivi-1 induced cell death in melanoma cells. However, silencing Drp1 and Mfn2 did not affect cell viability, but enhanced melanoma cell migration. We further show that dysregulated mitochondrial fusion by Mfn2 knockdowns suppressed the oxygen consumption rate of melanoma cells. Together, our findings suggest that mitochondrial dynamic alterations regulate melanoma cell migration and progression.

Evidence that Extreme Dilutions of Paclitaxel and Docetaxel Alter Gene Expression of In Vitro Breast Cancer Cells.

BACKGROUND: Gene expression analysis of cells treated with extreme dilutions or micro amounts of drugs has been used to provide useful suggestions about biological responses. However, most of the previous studies were performed on medicines being prepared from a variety of herbal and metal sources. This study investigated the effects of ultramolecular dilution of the taxane anti-cancer drugs, which are not commonly used in homeopathic medicines, on mRNA expression profiles of five key genes (p53, p21, COX-2, TUBB2A and TUBB3) in the breast cancer cell line MCF-7. METHOD: MCF-7 cells were exposed to paclitaxel (Taxol) or docetaxel (Taxotere) preparations (6X, 5C and 15C dilutions prepared from pharmacological concentration of 25 nmol/L) for 72 hours. The cell culture groups were evaluated with the trypan blue dye exclusion method for the proliferation/cytotoxicity rates, immuno-staining ß-tubulin for microtubule organization, and reverse transcription polymerase chain reaction for gene expression levels.Fold-change in gene expression was determined by the ΔΔCt method. RESULTS: The administration of diluted preparations had little or no cytotoxic effect on MCF-7 cells, but altered the expression of genes analyzed with a complex effect. According to the ΔΔCt method with a five-fold expression difference (p < 0.05) as a cut-off level, ultra-high dilutions of paclitaxel and docetaxel showed differential effects on the studied genes with a concentration-independent activity. Furthermore, the dilutions disrupted the microtubule structure of MCF-7 cells, suggesting that they retain their biological activity. CONCLUSION: Despite some limitations, our findings demonstrate that gene expression alterations also occur with ultra-high dilutions of taxane drugs.

ß-carotene treatment alters the cellular death process in oxidative stress-induced K562 cells.

Oxidizing agents (e.g., H2 O2 ) cause structural and functional disruptions of molecules by affecting lipids, proteins, and nucleic acids. As a result, cellular mechanisms related to disrupted macro molecules are affected and cell death is induced. Oxidative damage can be prevented at a certain point by antioxidants or the damage can be reversed. In this work, we studied the cellular response against oxidative stress induced by H2 O2 and antioxidant-oxidant (ß-carotene-H2 O2 ) interactions in terms of time, concentration, and treatment method (pre-, co-, and post) in K562 cells. We showed that co- or post-treatment with ß-carotene did not protect cells from the damage of oxidative stress furthermore co- and post-ß-carotene-treated oxidative stress induced cells showed similar results with only H2 O2 treated cells. However, ß-carotene pre-treatment prevented oxidative damage induced by H2 O2 at concentrations lower than 1,000 µM compared with only H2 O2 -treated and co- and post-ß-carotene-treated oxidative stress-induced cells in terms of studied cellular parameters (mitochondrial membrane potential [Δψm ], cell cycle and apoptosis). Prevention effect of ß-carotene pre-treatment was lost at concentrations higher than 1,000 µM H2 O2 (2-10 mM). These findings suggest that ß-carotene pre-treatment alters the effects of oxidative damage induced by H2 O2 and cell death processes in K562 cells.

Melatonin Prevents Mitochondrial Damage Induced by Doxorubicin in Mouse Fibroblasts Through Ampk-Ppar Gamma-Dependent Mechanisms.

BACKGROUND Doxorubicin (brand name: Adriamycin®) is used to treat solid tissue cancer but it also affects noncancerous tissues. Its mechanism of cytotoxicity is probably related to increased oxidation, mitochondrial dysfunction, and apoptosis. Melatonin is reported to have antiapoptotic and antioxidative effects. The aim of this study was to determine whether melatonin would counteract in vitro cytotoxicity of doxorubicin in mouse fibroblasts and determine the pathway of its action against doxorubicin-induced apoptosis. MATERIAL AND METHODS We measured markers of apoptosis (cytochrome-c, mitochondrial membrane potential, and apoptotic cell number) and oxidative stress (total oxidant and antioxidant status) and calculated oxidant stress index in 4 groups of fibroblasts: controls, melatonin-treated, doxorubicin-treated, and fibroblasts concomittantly treated with a combination of melatonin and doxorubicin. RESULTS Melatonin given with doxorubicin succesfully countered apoptosis generated by doxorubicin alone, which points to its potential as a protective agent against cell death in doxorubicin chemotherapy. This also implies that patients should be receiving doxorubicin treatment when their physiological level of melatonin is at its highest, which is early in the morning. CONCLUSIONS This physiological level may not be high enough to overcome doxorubicin-induced oxidative stress, but adjuvant melatonin treatment may improve quality of life. Further research is needed to verify our findings.

K562 cells display different vulnerability to H2O2 induced oxidative stress in differing cell cycle phases.

Oxidative stress can be defined as the increase of oxidizing agents like reactive oxygen and nitrogen species, or the imbalance between the antioxidative defense mechanism and oxidants. Cell cycle checkpoint response can be defined as the arrest of the cell cycle functioning after damaging chemical exposure. This temporary arrest may be a period of time given to the cells to repair the DNA damage before entering the cycle again and completing mitosis. In order to determine the effects of oxidative stress on several cell cycle phases, human erytroleukemia cell line (K562) was synchronized with mimosine and genistein, and cell cycle analysis carried out. Synchronized cells were exposed to oxidative stress with hydrogen peroxide (H2O2) at several concentrations and different times. Changes on mitochondria membrane potential (ΔΨm) of K562 cells were analyzed in G1, S, and G2 /M using Rhodamine 123 (Rho 123). To determine apoptosis and necrosis, stressed cells were stained with Annexin V (AnnV) and propidium iodide (PI) for flow cytometry. Changes were observed in the ΔΨm of synchronized and asynchronized cells that were exposed to oxidative stress. Synchronized cells in S phase proved resistant to the effects of oxidative stress and synchronized cells at G2 /M phase were sensitive to the effects of H2O2 -induced oxidative stress at 500 µM and above.

Molecularly imprinted nanoparticles with recognition properties towards diphtheria toxin for ELISA applications.

Plastic antibodies can be used for in vitro neutralization of biomacromolecules with different fragments due to their potential in separation, purification, chemical sensor, catalysis and drug production studies. These polymer nanoparticles with binding affinity and selectivity comparable to natural antibodies were prepared using functional monomer synthesis and copolymerization of acrylic monomers via miniemulsion polymerization. As a result, the in vitro cytotoxic effect from diphtheria toxin was reduced by MIPs. In vitro imaging experiments of polymer nanoparticles (plastic antibodies) were performed to examine the interaction of diphtheria toxin with actin filaments, and MIPs inhibited diphtheria toxin damage on actin filaments. The enzyme-linked immunosorbent assay (ELISA) was performed with plastic antibodies labeled with biotin, and it was determined that plastic antibodies could also be used for diagnostic purposes. We report that molecularly imprinted polymers (MIPs), which are biocompatible polymer nanoparticles, can capture and reduce the effect of diphtheria toxic and its fragment A.

Macromolecules can be imprinted by using their fragments as template molecules.MIPs gain an affinity for the template molecule by covalent binding, non-covalent interactions or ligand interactions, as well as the ability to bind, release and recognize the template molecule.The viability of cells treated with DT, NIPs and MIPs was determined by MTT assay.Immunofluorescence staining studies examined structural changes in actin filaments in HUVEC treated with DT, NIPs and MIPs.FA imprinted polymer has the ability to bind whole diphtheria toxin.FA-MIP gave significant results in terms of specificity in ELISA using diphtheria toxin.

Preparation of collagen modified photopolymers: a new type of biodegradable gel for cell growth.

In this study a new branched methacrylated poly(propylene glycol-co-lactic acid) (PPG-PLA-IEM) and methacrylated cellulose acetate butyrate resin (CAB-IEM) were synthesized. Hydrogels with various amounts of PPG-PLA-IEM and CAB-IEM (25, 50 and 75 wt% IEM modified) were prepared by photopolymerization. Collagen tethered PEG-monoacrylate (PEGMA-collagen) was prepared and introduced as a bioactive moiety to modify the hydrogel in order to enhance cell affinity. In vitro attachment and growth of 3T3 mouse fibroblasts and human umbilical vein endothelial cells (HUVEC) on the hydrogels with and without collagen were also investigated. It was observed that, the collagen improves the cell adhesion onto the hydrogel surface. With the increasing amount of collagen, cell viability increased by 28% for ECV304 (P < 0.05) and 30% for 3T3 (P < 0.05).

Polymeric nanoparticles for selective protein recognition by using thiol-ene miniemulsion photopolymerization.

The fabrication of molecularly imprinted nanoparticles (MIP-NPs) specific for myoglobin by using thiol-ene photopolymerization in miniemulsion was described. Allyl derivatives of phenylalanine as a functional monomer was synthesized and copolymerized with acrylic monomers via miniemulsion polymerization to produce NIP-NPs with approximately 74 nm number average particle diameter. FTIR and 1H-NMR analysis confirmed the synthesis of functional monomer. MIP-NPs were prepared in the existence of myoglobin as a template protein. Morphological investigations exhibited that the particle size of the MIP-NPs, increased compared to the corresponding NIPs and the mean particle diameter by number was measured as 141 nm with narrow distribution. NIP-NPs that were polymerized without myoglobin were found to have less affinity to the target protein. In addition, the rebinding ability of MIP-NPs was much bigger than that of the corresponding NIPs. ELISA results showed that MIPs interact particularly with the myoglobin and show little affinity for BSA in competitive binding experiments.HighlightsAllyl N,N-diallyl phenylalaninate was synthesized as a functional monomer.Imprinted nanoparticles were prepared by using thiol-ene photopolymerization in miniemulsion.The nanoparticles were 141 nm with narrow size distribution.The imprinted nanoparticles showed selectivity toward myoglobin.

Silencing HMGB1 expression inhibits adriamycin's heart toxicity via TLR4 dependent manner through MAPK signal transduction.

PURPOSE: Adriamycin (ADR) is a commonly used anti-cancer drug. ADR has toxic effects on cardiomyocytes and leads to heart failure. However, the underlying mechanism(s) by which ADR causes heart failure is still not clarified exactly. The aim of present study is to investigate whether ADR-induced heart failure is mediated via HMGB1/TLR4 to initiate the apoptosis through MAPK/AMPK pathways. METHODS: H9c2 cell line was used to create four groups as a control, HMGB1 inhibition, ADR, ADR+HMGB1 inhibition. Silencing HMGB1 was performed with specific small interfering RNA. ADR was used at 2 µM concentration for 36 and 48 hours. Protein and genes expressions, apoptosis was measured. RESULTS: Although ADR decreased AMPK, pAMPK, ERK1/2, pERK1/2, p38, JNK protein expression, ADR+HMGB1 inhibition led to change those protein expressions. The effect of silencing of HMGB1 prevented apoptosis induced by ADR in the cells. HMGB1 caused changes a kind of posttranscriptional modification on the TLR4 receptor. This posttranscriptional modification of TLR4 receptor led to decreased AMPK protein level, but phosphorylated-AMPK. This alternation of AMPK protein caused enhancing of JNK protein, resulting from the decline of p38 and ERK protein levels. Eventually, JNK triggered apoptosis by a caspase-dependent pathway. The number of TUNEL positive and active caspase 8 cells at ADR was high, although HMGB1 silencing could decrease the cell numbers. CONCLUSIONS: Inhibition of HMGB1 might prevent the lose of the cardiac cell by inhibition of apoptotic pathway, therefore HMGB1 plays an essential role as amplifying on ADR toxicity on the heart by TLR4.

Low dose monoethyl phthalate (MEP) exposure triggers proliferation by activating PDX-1 at 1.1B4 human pancreatic beta cells.

Phthalate plasticizers used in a wide range of common plastic products are released into the environment and may pose a risk of increased incidence of type 2 diabetes. In this work, we studied the effects of monoethyl phthalate (MEP), the metabolite of diethyl phthalate, exposure on 1.1B4 human pancreatic beta cells at low doses (1-1000 nM). We showed that MEP treatment induced proliferation in 1.1B4 cells. Also PCNA protein expression levels were increased related to proliferation induction. It has been noted that phthalates can exert estrogen mediated response by interacting with ER. In our study 24 h MEP treatment decreased ERα protein expression level conversely it increased the same protein expression level after 72 h treatment. Also MEP treatment decreased ERß expression after 72 h at 1.1B4 cells. Our results further show that insulin content of 1.1B4 cells were increased with low dose MEP treatment. Along with our insulin content results, PDX- 1 expression levels were also increased at 1.1B4 cells with MEP treatment. These findings suggest that MEP acts as an estrogenic compound and PPARγ agonist at lower concentrations. Also it should be noted that PDX-1 may be a critical regulator of 1.1B4 cells treated with MEP.

Effect of oxidative stress on in vivo ADP-ribosylation of eukaryotic elongation factor 2.

Different lines of evidence indicate that eukaryotic elongation factor 2 (eEF2) can be ADP-ribosylated endogenously. The physiological significance of this reaction has, however, remained unclarified. In order to address this issue we investigated the in vivo ADP-ribosylation of eEF2 and the effect of oxidative stress thereon. The investigation revealed that the endogenous ADP-ribosylation of eEF2 is complex and can take place in K562 cell lysates either under the action of endogenous transferase from [adenosine-14C]NAD or by direct binding of free [14C]ADP-ribose. These two types of ADP-ribosylation were distinguished by use of different treatments based on the chemical stability of the respective bonds formed. Under standard culture conditions, in vivo labeling of eEF2 in the presence of [14C]adenosine was reversed to about 65% in the presence of diphtheria toxin and nicotinamide. This finding implied that the modification that took place under physiological circumstances was, mainly, of an enzymic nature. On the other hand, H2O2-promoted oxidative stress gave rise to a nearly two-fold increase in the extent of in vivo labeling of eEF2. This was accompanied by a loss of eEF2 activity in polypeptide chain elongation. Oxidative stress specifically inhibited the subsequent binding of free ADP-ribose to eEF2. The results thus provide evidence that endogenous ADP-ribosylation of eEF2 can also take place by the binding of free ADP-ribose. This nonenzymic reaction appears to account primarily for in vivo ADP-ribosylation of eEF2 under oxidative stress.

Photopolymerized injectable RGD-modified fumarated poly(ethylene glycol) diglycidyl ether hydrogels for cell growth.

In this study, photopolymerized hydrogels of fumarated poly(ethylene glycol) diglycidyl-co- poly(ethylene glycol) diacrylate have been synthesized and modified with cell adhesion peptide, Arg-Gly-Asp (RGD). The structural and mechanical properties of the hydrogels are found to be poly(ethylene glycol) diacrylate (PEGDA) dependent. The percentage of gelation is increased from 72 to 89 wt.-% when the amount of the crosslinker co-monomer (PEGDA) in the hydrogel formulation is increased from 20 to 40 wt.-%. In the present case, the equilibrium mass swelling is decreased from 216 to 93%. The viscosities of the uncured formulations have also been measured and likewise, the results were influenced by the increasing amount of PEGDA that reduced the value from 83 to 36 cP. The compressive modulus of the prepared hydrogels was improved with the addition of the PEGDA. Cell growth experiments have been performed by comparing the properties of the hydrogels with and without RGD units. The results show that RGD units enhance the adhesion of cells to the surface of the hydrogels. SEM-EDS studies reveal that nitrogen and calcium are produced on the osteoblast-seeded surface of the scaffold within the culture time period. [Figure: see text].

In vitro evaluation of the use of zeolites as biomaterials: effects on simulated body fluid and two types of cells.

Various zeolites were kept in simulated body fluid (SBF) for different periods of time. Possible changes that may occur in the crystalline structures of zeolites and the chemical composition of SBF were determined by various analysis techniques after this treatment. The possible effects of two different zeolites on the morphology and viability of chronic myelogeneous leukemia and swiss albino fibroblast culture cells were also investigated. It was determined that when different types of zeolites were kept in the SBF for up to 14 days, their crystal structures were not affected. Observable amounts of Si were detected in the SBF samples after their treatment with all the zeolites investigated. Another variation in the chemical composition of SBF, worth to mention, was the increase of about 10% in its K content after the treatment carried out by using clinoptilolite. The zeolites KA and silicalite, which allowed the lowest and highest amount of silicon transfer into the SBF, respectively, were observed not to have any significant biological effect on the two different cell generations investigated under the conditions used in this study.

A quantitative colorimetric method of measuring alkaline phosphatase activity in eukaryotic cell membranes.

Alkaline phosphatase (ALP) is glycoprotein structured metalophosphatase with several defined functions. It is present in many tissues of all living beings from bacteria to mammals. The enzyme may catalyse the hydrolysis of various monophosphate esters at alkaline pH. The objective of this study was to quantify ALP functioning particularly in the membranes of eukaryotic cells. The membranes of seven different cells (myeloma cells; hybrid cells; erythroleukaemia cells; lymphocytes and erythrocytes) were tested for ALP activity using a cellular enzyme assay, which is based on the conversion of para-nitrophenylphosphate (p-NPP) to para-nitrophenol and the colorimetric determination of the resulting coloured product. The test system was optimised with respect to substrate concentration, reaction time and the number of cells used as a source of enzyme. The obtained values were converted to quantitative results through a standard curve created using commercial ALP. In order to determine the effect of serum concentration on enzyme activity, 1G2 hybridoma, which is among the cells used in this study and which synthesizes monoclonal antibody against human serum albumin, was produced in different serum concentrations ranging from 0 to 15%.

Effects of tricalcium phosphate bone graft materials on primary cultures of osteoblast cells in vitro.

The aim of this study was to evaluate beta-tricalcium phosphate (beta-TCP Cerasorb Curasan-Germany) graft materials on specific parameters of rat osteoblast activity in vitro. Primary culture osteoblastic cells were isolated from neonatal rat calvaria by sequential collagenase digestion. To analyze the effect of biomaterials on cell proliferation, cell numbers and viability of the cells were cultured on the graft material for 24, 48 or 96 h. Osteoblast cells cultured in DMEF-12 media supplemented with 10% fetal calf serum were used as the control group. [3H]thymidine was added during the last 2 h of the incubation. The cell numbers of each well were counted. Cell viability was estimated by counting the number of cells, which excluded trypan blue solution. Scanning electron microscopy was used to observe for visualizing the interactions between osteoblastic cells and TCP graft material. The proportion of cells undergoing DNA synthesis, estimated by thymidine uptake, was significantly (P<0.05) greater on the control group after the 24- and 48-h incubations. Regarding the cell numbers the difference was not statistically significant for the three time points. The number of viable cells recovered was similar for the two groups. No morphological differences were observed in cell morphology on TCP graft material and the control group. The results demonstrate that TCP graft material has no adverse effect on cell count, viability and morphology, and this material provides a matrix that favors limited cell proliferation.