Hyaluronic acid engrafted metformin loaded graphene oxide nanoparticle as CD44 targeted anti-cancer therapy for triple negative breast cancer

BackgroundTriple negative breast cancer (TNBC) is the most aggressive form of breast cancer with limited treatment modalities. It is associated with high propensity of cancer recurrence.MethodsUV Spectroscopy, FTIR, DLS, Zeta potential, TEM and SEM were employed to characterize nanoparticles. MTT assay, Wound healing assay, SEM, Immunocytochemistry analysis, Western blot, RT-PCR, mammosphere formation assay were employed to study apoptosis, cell migration and stemness. Tumor regression was studied in chick embryo xenograft and BALB/c mice model.ResultsHylaluronic acid engrafted metformin loaded graphene oxide (HA-GO-Met) nanoparticles exhibited an anti-cancer efficacy at much lower dosage as compared to metformin alone. HA-GO-Met nanoparticles induced apoptosis and inhibited cell migration of TNBC cells by targeting miR-10b/PTEN axis via NFkB-p65. Upregulation of PTEN affected pAKT(473) expression that induced apoptosis. Cell migration was inhibited by reduction of pFAK/integrinβ1 expressions. Treatment inhibited epithelial mesenchymal transition (EMT) and reduced stemness as evident from the increase in E-cadherin expression, inhibition of mammosphere formation and low expression levels of stemness markers including nanog, oct4 and sox2 as compared to control. Moreover, tumor regression was studied in chick embryo xenograft and BALB/c mice model. HA-GO-Met nanoparticle treatment reduced tumor load and nullified toxicity in peripheral organs imparted by tumor.ConclusionsHA-GO-Met nanoparticles exhibited an enormous anti-cancer efficacy in TNBC in vitro and in vivo.General significanceHA-GO-Met nanoparticles induced apoptosis and attenuated cell migration in TNBC. It nullified overall toxicity imparted by tumor load. It inhibited EMT and reduced stemness and thereby addressed the issue of cancer recurrence.     

Inhibition of Escherichia coli DNA polymerase-I by the anti-cancer drug cis-diaminedichloroplatinum(II): what roles do polymerases play in cis-platin-induced cytotoxicity?

Activities of Escherichia coli DNA polymerase-I were examined in the presence of the anti-tumor drug cis-diaminedichloroplatinum(II) and its inactive geometric isomer trans-diaminedichloroplatinum(II). The trans-isomer did not inhibit the enzyme activity. The anti-tumor drug, on the other hand, retarded the enzyme in its ability to extend the primer strand of DNA. Two alternative mechanisms of inhibition, covalent binding of cis-diaminedichloroplatinum(II) to the polymerase and to the template DNA, were explored. Selective preincubations of the platinum drug with the polymerase and DNA reveal that the inhibition is primarily due to covalent binding to the enzyme. The rates of inhibition were found to be first order in enzyme and zeroth order in platinum in the concentration range 0.05-3.0 mM. A mechanism that deals with the formation of an initial platinum-polymerase-I complex with a binding constant > 10(5) M(-1) followed by a further reaction to form an inhibitory complex is consistent with the kinetic data. The rate limiting first order rate constant for the formation of the inhibitory complex is comparable to that observed for the thiol coordination of peptides containing cysteine residues. Analyses of known structures and functions of catalytic domains of various polymerases point to the direction that the inhibition is perhaps due to the distortion of the DNA binding domain of the enzyme due to platinum coordination.     

Horseradish peroxidase-catalyzed conversion of iodine to iodide in presence of EDTA and H2O2

EDTA (4 mM) blocks the oxidation of iodide to I-3 (increase of extinction at 353 nm) by H2O2 catalyzed by horseradish peroxidase, which is reversed by the addition of an equimolar concentration of Zn2+. Addition of suboptimal concentration of EDTA (2 mM) not only decreases the rate of forward reaction of I-3 formation but also causes loss of extinction of the same when I-3 is generated. The loss of extinction of I-3 is proportional to the enzyme concentration and is blocked by azide, the inhibitor of the peroxidase. EDTA also causes bleaching of nonenzymatically formed I-3 (from iodide and H2O2) only in the presence of horseradish peroxidase, and the effect is reversed by the equimolar concentration of Zn2+. Both the bleaching of I-3 by EDTA and reversal of EDTA effect by Zn2+ are sensitive to azide. The decrease of extinction of I-3 (formed by dissolving iodine in KI solution) is dependent on EDTA, H2O2, and horseradish peroxidase. Molecular iodine is also bleached but at a slower rate than I-3. Evidence is presented to show that this bleaching of I-3 is due to enzymatic conversion of I-3 to iodide in presence of EDTA and H2O2 and this involves pseudocatalatic degradation of H2O2 to O2.     

Inhalation toxicity of methylisocyanate: assessment of germ cell mutagenicity and reproductive effects in rats.

Adult male Wistar rats were exposed to methylisocyanate (MIC, 3.2 mg/l, single inhalation exposure for 8 min under static condition) or ethyl methanesulphonate (EMS, 150 mg/kg, single ip dose) for the assessment of germ cell mutagenicity and reproductive effects. Sequential matings of treated males with normal females on days 1-7, 8-14 and 15-21 post-exposure did not indicate any induction of dominant lethal mutation (increased frequency of preimplantation losses and early fetal deaths) by MIC but it was significantly induced by EMS as compared to respective controls. Males, necropsied after 21 days of exposure, showed no effect of MIC on epididymal sperm density and morphology. EMS also had no effect on sperm density but it significantly induced morphological abnormalities in sperm as compared to untreated controls. There was an acute and transitional reduction in reproductive performance (10-21%) of MIC-exposed males during days 1-14 post-exposure followed by recovery to the normal level during days 15-21 post-exposure. The progeny of MIC-exposed males was also normal in terms of litter size, litter weight, neonatal survival and body weight gain in litters up to 10 days post-partem. It is concluded with the evidence at hand that the observed failure of MIC to cause germ cell mutagenicity is related to its poor biodistribution to the target site(s) and a transient reduction in the reproductive performance of MIC-exposed males is a result of general stress and disconsolate copulation.     

Superior Appetite Hormone Profile After Equivalent Weight Loss by Gastric Bypass Compared to Gastric Banding

The goal of this study was to understand the mechanisms of greater weight loss by gastric bypass (GBP) compared to gastric banding (GB) surgery. Obese weight‐ and age‐matched subjects were studied before (T0), after a 12 kg weight loss (T1) by GBP (n = 11) or GB (n = 9), and at 1 year after surgery (T2). peptide YY_3–36 (PYY_3–36), ghrelin, glucagon‐like peptide‐1 (GLP‐1), leptin, and amylin were measured after an oral glucose challenge. At T1, glucose‐stimulated GLP‐1 and PYY levels increased significantly after GBP but not GB. Ghrelin levels did not change significantly after either surgery. In spite of equivalent weight loss, leptin and amylin decreased after GBP, but not after GB. At T2, weight loss was greater after GBP than GB (P = 0.003). GLP‐1, PYY, and amylin levels did not significantly change from T1 to T2; leptin levels continued to decrease after GBP, but not after GB at T2. Surprisingly, ghrelin area under the curve (AUC) increased 1 year after GBP (P = 0.03). These data show that, at equivalent weight loss, favorable GLP‐1 and PYY changes occur after GBP, but not GB, and could explain the difference in weight loss at 1 year. Mechanisms other than weight loss may explain changes of leptin and amylin after GBP.     

A role of calcium in altered sodium ion transport of hypertensives?

Research on the etiology of essential hypertension has led to many reports of altered ion transport in cells from hypertensive patients and animal models. Abnormalities in sodium and calcium ion gradients and transport in vascular smooth muscle, neuronal tissue, cardiac muscle as well as erythrocytes have been extensively investigated. It is not clear whether these abnormalities are of primary or secondary nature. The current knowledge of sodium and calcium ion transport in essential hypertension is briefly reviewed here. Furthermore, evidence is presented which suggests a role of calcium in the regulation of sodium transport activity.