Resorcylidene Aminoguanidine (RAG) Improves Cardiac Mitochondrial Bioenergetics Impaired by Hyperglycaemia in a Model of Experimental Diabetes

Diabetes is associated with a mitochondrial dysfunction. Hyperglycaemia is also clearly recognized as the primary culprit in the pathogenesis of cardiac complications. In response to glycation and oxidative stress, cardiac mitochondria undergo cumulative alterations, often leading to heart deterioration. There is a continuous search for innovative treatment strategies for protecting the heart mitochondria from the destructive impact of diabetes. Aminoguanidine derivatives have been successfully used in animal model studies on the treatment of experimental diabetes, as well as the diabetes-driven dysfunctions of peripheral tissues and cells. Considerable attention has been paid particularly to β-resorcylidene aminoguanidine (RAG), often shown as the efficient anti-glycation and anti-oxidant agent in both animal studies and in vitro experiments. The aim of the present study was to test the hypothesis that RAG improves oxidative phosphorylation and electron transport capacity in mitochondria impaired by hyperglycaemia. Diabetes mellitus was induced in Wistar rats by a single intraperitoneal injection of streptozotocin (70 mg/kg body weight). Heart mitochondria were isolated from healthy rats and rats with streptozotocin-diabetes. Mitochondrial respiratory capacity was measured by high resolution respirometry with the OROBOROS Oxygraph-2k according to experimental protocol including respiratory substrates and inhibitors. The results revealed that RAG protects the heart against diabetes-associated injury by improving the mitochondrial bioenergetics, thus suggesting a possible novel pharmacological strategy for cardioprotection

Gliclazide may have an antiapoptotic effect related to its antioxidant properties in human normal and cancer cells

Experimental and clinical studies suggest that gliclazide may protect pancreatic β-cells from apoptosis induced by an oxidative stress. However, the precise mechanism(s) of this action are not fully understood and requires further clarification. Therefore, using human normal and cancer cells we examined whether the anti-apoptotic effects of this sulfonylurea is due to its free radical scavenger properties. Hydrogen peroxide (H2O2) as a model trigger of oxidative stress was used to induce cell death. Our experiments were performed on human normal cell line (human umbilical vein endothelial cell line, HUVEC-c) and human cancer cell lines (human mammary gland cell line, Hs578T; human pancreatic duct epithelioid carcinoma cell line, PANC-1). To assess the effect of gliclazide the cells were pre-treated with the drug. The 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide assay was employed to measure the impact of gliclazide on cell viability. Generation of reactive oxygen species, mitochondrial membrane potential (∆Ψm), and intracellular Ca2+ concentration [Ca2+] were monitored. Furthermore, the morphological changes associated with apoptosis were determined using double staining with Hoechst 33258-propidium iodide (PI). Gliclazide protects the tested cells from H2O2-induced cell death most likely throughout the inhibition of ROS production. Moreover, the drug restored loss of ΔΨm and diminished intracellular [Ca2+] evoked by H2O2. Double staining with Hoechst 33258-PI revealed that pre-treatment with gliclazide diminished the number of apoptotic cells. Our findings indicate that gliclazide may protect both normal and cancer human cells against apoptosis induced by H2O2. It appears that the anti-apoptotic effect of the drug is most likely associated with reduction of oxidative stress

Aguas de lastre, problemas de biologicas contaminaciones de aguas portuarias de Baltico

Conferència realitzada per la doctora Zofia Józwiak de la Universidad Politécnica de Szczecin (Polònia

Relationship between therapeutic efficacy of doxorubicin-transferrin conjugate and expression of P-glycoprotein in chronic erythromyeloblastoid leukemia cells sensitive and resistant to doxorubicin

Background Conjugation of anti-neoplastic agents with human proteins is a strategy to diminish the toxic side effects of anthracycline antibiotics. We have developed a novel doxorubicin-transferrin (DOX-TRF) conjugate aimed to direct anticancer drugs against therapeutic targets that display altered levels of expression in malignant versus normal cells. Our previous work has shown that the cellular bio-distribution of the conjugate is dependent on a dynamic balance between influx and efflux processes. Here, we set out to investigate whether P-glycoprotein (P-gp) expression may affect DOXTRF conjugate-induced cellular drug accumulation and cytotoxicity. Results All experiments were carried out on human erythromyeloblastoid cells exhibiting P-gp over-expression (K562/DOX) and its drug sensitive parental line (K562). MTT cytotoxicity, flow cytometry, fluorescence microscopy and RT-PCR assessments revealed that the investigated conjugate (DOX-TRF) possesses a greater cytotoxic potential than free DOX. Conclusion Our data suggest that the newly developed DOXTRF conjugate is a less P-gp dependent substrate than free DOX and, consequently, may be used in a clinical setting to increase treatment efficacy in resistant human tumors.Grant no. 545/ 756 of the University of Lodz, Poland

Transferrin as a drug carrier: Cytotoxicity, cellular uptake and transport kinetics of doxorubicin transferrin conjugate in the human leukemia cells.

Leukemias are one of most common malignancies worldwide. There is a substantial need for new chemotherapeutic drugs effective against this cancer. Doxorubicin (DOX), used for treatment of leukemias and solid tumors, is poorly efficacious when it is administered systemically at conventional doses. Therefore, several strategies have been developed to reduce the side effects of this anthracycline treatment. In this study we compared the effect of DOX and doxorubicin-transferrin conjugate (DOX-TRF) on human leukemia cell lines: chronic erythromyeloblastoid leukemia (K562), sensitive and resistant (K562/DOX) to doxorubicin, and acute lymphoblastic leukemia (CCRF-CEM). Experiments were also carried out on normal cells, peripheral blood mononuclear cells (PBMC). We analyzed the chemical structure of DOX-TRF conjugate by using mass spectroscopy. The in vitro growth-inhibition assay XTT, indicated that DOX-TRF is more cytotoxic for leukemia cells sensitive and resistant to doxorubicin and significantly less sensitive to normal cells compared to DOX alone. During the assessment of intracellular DOX-TRF accumulation it was confirmed that the tested malignant cells were able to retain the examined conjugate for longer periods of time than normal lymphocytes. Comparison of kinetic parameters showed that the rate of DOX-TRF efflux was also slower in the tested cells than free DOX. The results presented here should contribute to the understanding of the differences in antitumor activities of the DOX-TRF conjugate and free drug

Recent Insights into Plant miRNA Biogenesis: Multiple Layers of miRNA Level Regulation

MicroRNAs are small RNAs, 20–22 nt long, the main role of which is to downregulate gene expression at the level of mRNAs. MiRNAs are fundamental regulators of plant growth and development in response to internal signals as well as in response to abiotic and biotic factors. Therefore, the deficiency or excess of individual miRNAs is detrimental to particular aspects of a plant’s life. In consequence, the miRNA levels must be appropriately adjusted. To obtain proper expression of each miRNA, their biogenesis is controlled at multiple regulatory layers. Here, we addressed processes discovered to influence miRNA steady-state levels, such as MIR transcription, co-transcriptional pri-miRNA processing (including splicing, polyadenylation, microprocessor assembly and activity) and miRNA-encoded peptides synthesis. MiRNA stability, RISC formation and miRNA export out of the nucleus and out of the plant cell also define the levels of miRNAs in various plant tissues. Moreover, we show the evolutionary conservation of miRNA biogenesis core proteins across the plant kingdom