Nanoparticle-Modified Apoferritin Nanotransfer for Targeted Cytostatic Transport.

BACKGROUND: Ferritin is a globular intracellular protein that acts as the main reservoir for iron. Malignancies are associated with increased plasma ferritin concentrations. A number of studies show that tumor cells express high levels of transferrin receptors (TfR). Increased TfR expression was observed in prostate carcinoma. Apoferritin (APO) can be used as a protein nanotransporter into which a suitable medicinal substance can be encapsulated. Nanoparticles increase the permeability of tumor cells to nanotransporters and have a photothermal effect. The aim of this study was to encapsulate doxorubicin (DOX) into APO and to modify the resulting APO/DOX with gold (AuNPs) and silver nanoparticles prepared by green synthesis (AgNPsGS). METHODS: APO was characterized using 10% sodium dodecylsulphate polyacrylamide gel electrophoresis (SDS-PAGE) - 120 V, 60 min, 24 mM Tris, 0.2 M glycine, 3 mM SDS. DOX fluorescence (Ex 480 nm; Em 650 nm) was observed, with a typical absorption maximum at 560 nm. Electrochemical measurement was performed in Brdicka solution (three-electrode setup). AgNPsGS were prepared by green synthesis using clover (Trifolium pratense L.). RESULTS: An electrophoretic study of APO and APO/DOX (5-100 μg/mL) was performed and the behavior of APO and APO/DOX (10 μM) as a function of pH was monitored. In an acidic environment, APO forms subunits of about 20 kDa; in an alkaline medium, it forms a globular protein of about 450 kDa. A change in APO/DOX mobility (about by 10%) was observed. A film of gold nanoparticles was applied to the APO/DOX surface. APO/DOX-AuNPs were washed with ultra-pure water. pH-dependent release of DOX a was monitored. The amount of DOX analyzed was increased by up to 50%. Furthermore, an AgNPsGS-DOX complex (1 mg AgNPsGS/100 μM DOX) was generated and prepared. Subsequently, the AgNPsGS-DOX complex was encapsulated into APO. To further improve therapeutic efficacy, the APO/AgNPsGS-DOX complex was coated with an Au layer. APO/AgNPsGS-DOX/AuNPs were stable and DOX was released from the complex after physical parameters had changed. CONCLUSION: APO nanocomplexes were prepared and modified to increase therapeutic efficacy against tumors. Tumor cell targeting was achieved by binding to TfR and via increased tumor cell permeability and retention. Release of the drug was made possible due to a pH change and photothermal activation that will now be tested. This work was supported by COST European Cholangiocarcinoma Network CA18122 and International Collaboration Project of The European Technology Platform for Nanomedicine. The authors declare they have no potential conflicts of interest concerning drugs, products, or services used in the study. The Editorial Board declares that the manuscript met the ICMJE recommendation for biomedical papers. Submitted: 21. 3. 2019 Accepted: 14. 5. 2019.

[Fullerene Doxorubicin Nanotransporter for Target Interaction with mutated gene BRCA2]. / Fullerenový nanotransportér doxorubicinu pro cílenou interakci s mutovaným genem BRCA2.

BACKGROUND: Malignant breast tumors are in developed countries, the most common cancer affecting mainly women. It is estimated that approximately 5-10% of breast cancers are conditioned by genetic family burdens, caused by mutation in the BRCA2 gene. In the course of the treatment doxorubicin is frequently used therapeutics. Despite its therapeutic efficacy, however, it shows high cardiotoxicity. Possibility to increase the therapeutic window, represent nanotransporters. Fullerenes are nanoparticles composed of carbon atoms whose physical-chemical properties indicate high stability. The complex of fullerene and doxorubicin enables the targeted method for the treatment. The aim of this work is to develop a nanotransporter system with an expected cytostatic effect without significant toxic effects. MATERIAL AND METHODS: To 5mg of fullerene 0.5ml of distilled water was added and solution was subsequently placed for 30 min in an ultrasonic bath (50 W). Fullerenes with bound doxorubicin (DOXO) were purified from unbound DOXO by centrifugation (16,000g). For DOXO analysis acetate buffer was used. Fe2O3-NPs were prepared by reduction with borohydride and ammonia. Thereafter Fe2O3-AuNPs were prepared by thermal synthesis. RESULTS: Carbon nanotransporter (fullerene) for binding of doxorubicin (FULLER-DOXO) was designed and subsequently studied by biophysical methods. We have found that FULLER-DOXO size is larger than 100 nm and the zeta potential is around 24 mV. DOXO, interacts with FULLER by the electrostatic interaction, and its volume increases with the applied concentration (R2 = 0.96). In the following experiment FULLER-DOXO was modified with oligodeoxynucleotide (ODN; 10 µg/ml), and this way was FULLER-DOXO-ODN1 complex prepared. Bound ODN represents a specific sequence for targeting the complex to a point mutation in the BRCA2 gene. In order to prove the interaction magnetic gold nanoparticle modified with the complementary sequence to the test nanotransporter was designed (ODN2-Fe2O3-AuNPs). Formed complex (FULLER-DOXO-ODN1-ODN2-Fe2O3-AuNPs) was subsequently confirmed by several independent techniques. CONCLUSION: We assume that the proposed nanoconstruct will be able to use for genetic targeting of anticancer drug.Key words: doxorubicin - breast cancer - fullerenes - magnetic gold nanoparticles The work was realized with the support of the project NANO LPR 2017 Liga proti rakovine Praha and The European Technology Platform for Nanomedicine. The authors declare they have no potential conflicts of interest concerning drugs, products, or services used in the study. The Editorial Board declares that the manuscript met the ICMJE recommendation for biomedical papers.Submitted: 6. 3. 2017Accepted: 26. 3. 2017.

[Zinc-modified Nanotransporter for Target Drug Therapy of Breast Cancer]. / Zinecnatými ionty modifikovaný nanotransportér antracyklinových antibiotik pro cílenou terapii nádoru prsu.

BACKGROUND: In the centre of nanomedical interest stands the nanotechnological modification of anthracycline antibiotics, which are often used in antitumor treatment of hematological malignancies and solid tumors. Chitosan nanoparticles are gaining more attention in the field of targeted transport of drugs because of their stability, low toxicity and simple preparation. The main objective of the project, was the design of chitosan nanotransporter of anthracycline antibiotics with zinc modified surface, for a specific interaction with metallothionein. MATERIAL AND METHODS: The chitosan nanoparticles with encapsulated doxorubicin were prepared by a dissolution of 5g of chitosan in 3% solution of acetic acid and TPP (0.25% w/v) and doxorubicin (0.5mg/ml). Fe2O3-NPs were prepared by a reduction with borohydride and using ammonia. Thereafter Fe2O3-AuNPs were prepared by thermal synthesis. The amount of doxorubicin and Zn2+ was determined using DPV. RESULTS: Chitosan nanotransporter with anthracycline antibiotics (CHIT-Zn-DOXO-Fe2O3-AuNPs) was designed and subsequently studied by biophysical methods. Inside of the nanometric structure is electrostatically bound doxorubicin (concentration 10 µM, CHIT-DOXO). Moreover metallothionein is a molecule rich in cysteine and thanks to its free sulphhydryl groups is capable of bonding with the zinc ions. We have decided to use this ability for a construction of the nanotransporter for its targeted direction towards the tumor tissue (CHIT-Zn-DOXO). We have shown significant increases of a metallothionein (MT) level in malignant tumors in many of our previous experiments. MT into its domains binds heavy metal ions (naturally zinc ions) and keeps the homeostasis in equilibrium this way. Therefore we have decided to observe the ability of modified chitosan nanoparticles (CHIT-Zn-DOXO, 100 µg/ml) for MT protein binding (magnetic gold nanoparticles were modified by MT, 100 µg/ml, Fe2O3-AuNPs) in the other part of our experiment. The efficiency of the chitosan nanoparticle bond modified by zinc ions (CHIT-Zn-DOXO) to the MT (CHIT-Zn-DOXO-Fe2O3-AuNPs-MT) increased by more than 30% compared with the unmodified nanoparticle (CHIT-DOXO). CONCLUSION: We assume that the new nanotransporter is specific for its bioavailability, increased uptake of the drug from bloodstream in the tumor tissue area and low toxicity for an untargeted tissue.Key words: chitosan - magnetic gold nanoparticles - breast cancer - doxorubicin The work was realized with the support of the project NANODRUGS 328/2017/FaF and The European Technology Platform for Nanomedicine. The authors declare they have no potential conflicts of interest concerning drugs, products, or services used in the study. The Editorial Board declares that the manuscript met the ICMJE recommendation for biomedical papers.Submitted: 6. 3. 2017Accepted: 26. 3. 2017.

Levels of transforming growth factor beta and transforming growth factor beta receptors in rat liver during growth, regression by apoptosis and neoplasia.

Transforming growth factor beta1 (TGF-beta1) has been implicated as inhibitor of cell proliferation and a potent inducer of apoptosis in vitro and in vivo after the administration of high doses. To assess the role of endogenous TGF-beta1, we quantitated the cytokine and its receptors in rat liver during regenerative and hyperplastic growth, regression by apoptosis, and in hepatocellular carcinoma (HCC). This was accomplished by Northern blot analysis and by RNase protection assay of the messenger RNA (mRNA) of TGF-beta1 and TGF-beta receptors (TbetaR) types I to III and by an activity bioassay of the TGF-beta proteins. Untreated rat livers were found to contain 15.6 +/- 4.8 ng TGF-beta1 protein/g tissue; TGF-beta2 protein was not detected. To induce toxic cell death and subsequent regenerative DNA synthesis in the liver, rats were treated with a necrogenic dose of carbon tetrachloride (CCl4). After 24 and 48 hours, there was an upregulation of TGF-beta1 (mRNA, up to tenfold; protein, about twofold) and of TbetaRs (mRNA: two- to fourfold); that indicates an overall enhanced production of and sensitivity to TGF-beta1, which may serve to confine the regenerative response. Hyperplastic liver growth and regression of the hyperplasia were induced by treatment with cyproterone acetate (CPA) or nafenopin (NAF) followed by withdrawal; neither mRNAs of TGF-beta1 and TbetaR types I to III nor TGF-beta1 protein exhibited significant changes during the growth phase or during regression by apoptosis. We also studied neoplastic growth. HCC, obtained after long-term treatment with NAF, exhibited high rates of cell replication and apoptosis. The majority of lesions contained mRNA and protein of TGF-beta1 and mRNA of TbetaR types I to III at concentrations similar to those of the surrounding tissue. In conclusion, during liver regeneration there is a pronounced upregulation of expression of both TGF-beta1 and TbetaRs I to III, but not during mitogen-induced liver growth or regression. It appears that apoptosis is induced via altered local concentration of TGF-beta1, in a paracrine and/or autocrine way. By this mechanism the lethal effects of TGF-beta1 may be locally confined, and overshoots of apoptosis in the liver may be prevented.

Inherent increase of apoptosis in liver tumors: implications for carcinogenesis and tumor regression.

We quantitatively assessed rates of cell replication and of apoptosis during the development and regression of liver cancer. In rats, apoptotic activity gradually increased from normal liver to putative preneoplastic foci (PPF), to hepatocellular adenoma (HCA), and to hepatocellular carcinoma (HCC). At all stages, rates of cell replication were higher than of apoptosis, allowing a preferential net gain of (pre)neoplastic cells. As in rats, in human HCC, birth and death rates were increased manifold, indicating a species-independent phenomenon. Implications of the increasing cell turnover were studied in rats using the administration and withdrawal of nafenopin (NAF), a liver mitogen and nongenotoxic carcinogen. Prolonged NAF treatment enhanced cell number in normal liver by 25%, while PPF and liver tumors were amplified at least 100-fold. After stopping NAF treatment, cell replication ceased, while cell elimination by apoptosis was increased in normal and (pre)neoplastic liver. HCA and HCC showed the most pronounced shifts from replication toward apoptosis. As a result, 5 weeks after halting NAF, 20% of cells in normal liver, but about 85% of (pre)neoplastic lesions including HCC, were eliminated. The implications of these findings include that nongenotoxic carcinogens can act as survival factors even for malignant cells. Furthermore, tumor cells not only exhibit excessive proliferation, but also undergo apoptosis at rates that far exceed those in normal tissue. Therefore, inhibition of cell death by the survival activity of nongenotoxic carcinogens results in selective growth of (pre)neoplastic lesions. On the other hand, blockade of survival effects leads to excessive apoptosis in (pre)neoplasia and seems promising as a therapeutic concept for the selective elimination of (liver) cancer.

Apoptosis and multistage carcinogenesis in rat liver.

Apoptosis is a type of active cell death. It is involved in the homeostasis of cell number in tissues and is controlled by the growth regulatory network in the organism. It is also involved in the active removal of damaged cells. We have studied the role of apoptosis in cancer pre-stages and overt cancer in vivo, using rat liver as our main model system. Quantitative determination of apoptosis in histological specimens revealed that the rate of apoptosis tends to increase from normal to (pre)neoplastic to malignant cells. Thereby active cell death largely counterbalances the increasing replicative activity in developing malignancy. Tumor promoters shift the balance in favor of cell replication, whereas promoter withdrawal, fasting or TGF-beta 1 favor apoptosis (anti-promotion). Preneoplastic cells are more susceptible than normal liver cells to stimulation of both cell replication or cell death. Consequentially (pre)neoplastic tissue may preferentially grow or die during the appropriate treatment. Regimens that favor apoptosis and lower cell replication are shown to result in the elimination of preneoplastic cell clones from the liver (anti-initiation) and to reduce the cancer risk of the animal.

In situ detection of fragmented DNA (TUNEL assay) fails to discriminate among apoptosis, necrosis, and autolytic cell death: a cautionary note.

Detection of DNA fragments in situ using the terminal deoxyribonucleotidyl transferase (TDT)-mediated dUTP-digoxigenin nick end labeling (TUNEL) assay is increasingly applied to investigate active cell death (apoptosis). We studied the specificity of the assay in well-defined models of apoptosis and necrosis as well as in postmortem autolysis in rat liver. During involution of liver hyperplasia, which follows stopping treatment with the hepatomitogens cyproterone acetate (CPA) or nafenopin (NAF), numerous apoptotic hepatocytes could be observed with TUNEL-positive chromatin residues. A similar TUNEL-positive reaction appeared in necrotic hepatocytes after a cytotoxic dose of carbon tetrachloride (CCl4) or N-nitrosomorpholine (NNM). Also, in insufficiently fixed, autolytic livers TUNEL-positive nuclei were observed. Thus, DNA fragmentation is common to different kinds of cell death; its detection in situ should not be considered a specific marker of apoptosis.

Food restriction eliminates preneoplastic cells through apoptosis and antagonizes carcinogenesis in rat liver.

Restriction of dietary calories reduces cancer formation in experimental animals and probably also in humans. This effect is generally attributed to the inhibitory effect of fasting on cell proliferation. Here we studied the effect of fasting on physiological cell death through apoptosis by using rat liver as a model. (i) In normal liver, involution of hyperplasia by apoptosis was reinforced by food withdrawal and suppressed by feeding. Complete food withdrawal for 8 days or food reduction by 40% for 3 months eliminated 20-30% of normal liver cells through apoptosis. (ii) Putative preneoplastic liver foci exhibited severalfold higher rates of DNA replication and apoptosis than unaltered liver. Food restriction lowered DNA replication but increased apoptosis, which reduced the number and volume of putative preneoplastic liver foci by 85% within 3 months. Subsequent return to ad libitum feeding normalized cell replication and apoptosis but clear differences in the volume and number of putative preneoplastic liver foci persisted throughout the following 17 months. Treatment of animals after food restriction with nafenopin, a peroxisome proliferator and potent tumor promoter, produced only half as many hepatocellular adenomas and carcinomas as in animals fed unrestrictedly throughout their lifetime. This indicates that food restriction had actually eliminated a part of the initiated cells. This study demonstrates that food restriction preferentially enhances apoptosis of preneoplastic cells. This effect in combination with lowered cell replication provides protection from carcinogenesis.

High-level resistance to cycloheximide resulting from an interaction of the mutated pdr3 and cyh genes in yeast.

In addition to pdr3-1, the S. cerevisiae nuclear pleiotropic drug resistance mutant 2D was found to contain another recessive nuclear mutation, cyh, conferring specific resistance to cycloheximide only. The cycloheximide resistance level due to either the pdr3-1 or the cyh mutation alone was low and was not altered by the ogd1 mutation which increased the physiological acidification of the culture. When pdr3-1 and cyh mutations occurred simultaneously in the haploid yeast strain their interaction was synergistic and resulted in high-level resistance to cycloheximide.

The OGD1 gene, affecting 2-oxoglutarate dehydrogenase in S. cerevisiae, is closely linked to HIS5 on chromosome IX.

Ogd1 mutants of Saccharomyces cerevisiae are deficient in mitochondrial 2-oxoglutarate dehydrogenase activity; they cannot grow on glycerol and produce an increased amount of organic acids during growth on glucose as substrate. Using gamma ray-induced rad52-mediated chromosome loss the ogd1 mutation can be assigned to chromosome IX. Tetrad analysis of crosses between ogd1 and other markers on chromosome IX revealed that the OGD1 gene maps on the left arm of this chromosome 1.9 cM from his5.