A multikinase inhibitor of the Raf/mitogen‐activated protein kinase kinase (MEK)/extracellular signal‐regulated kinase (ERK) pathway, sorafenib, is increasingly being used in the management of ...hepatocellular carcinoma, and its combination with conventional chemotherapeutics has stimulated particular interest. Although the combination of sorafenib with doxorubicin (DOX) is presently being investigated in a phase III randomized trial, little is known about the molecular mechanisms of their interaction. Because DOX causes cell death through upregulation of the MEK/ERK pathway, and sorafenib has an opposite influence on the same cascade, we hypothesized that co‐treatment with these drugs may lead to an antagonistic effect. DOX treatment arrested proliferation and induced autophagic cell death in Hep3B cells, whereas apoptotic changes were not conspicuous. Sorafenib alone affected viability and caused massive mitochondrial degradation. However, when added together with DOX, sorafenib facilitated cell cycle progression, increased survival, and reduced autophagy. To evaluate the molecular mechanisms of this phenomenon, we examined the expression of ERK1/2, protein kinase B (Akt), and cyclin D1, as well as the members of Bcl‐2 family. ERK1/2 activation induced by DOX was suppressed by sorafenib. Similarly, ERK targeting with the selective inhibitor U0126 impaired DOX‐induced toxicity. Treatment with sorafenib, either alone or in combination with DOX, resulted in Akt activation. The role of sorafenib‐induced degradation of cyclin D1 in the suppression of DOX efficiency is discussed. In conclusion, MEK/ERK counteraction, stimulation of survival via Akt and dysregulation of cyclin D1 could contribute to the escape from DOX‐induced autophagy and thus promote cancer cell survival. The use of MEK/ERK inhibitors in combination with chemotherapeutics, intended to enhance anticancer efficacy, requires the consideration of possible antagonistic effects.
Here we demonstrate the antagonistic effect of combined treatment by doxorubicin and sorafenib in hepatocellular carcinoma Hep3B cells. ERK1/2 signaling and its counteractive regulation by these drugs appears to play a crucial role in predicting pro‐survival outcome of drug combination. The use of MEK/ERK targeting in the treatment of hepatocellular carcinoma combined with doxorubicin could reduce the efficacy of single‐drug therapy.
Tools commonly used for shredding rubber waste, currently produced, are made of neatly cast iron in the composite is to avoid the presence of sulfur and phosphorus. In this paper are presented the ...main structural material changes that occur in different areas, located at different distances from the active surface of tools. Structural changes occurred mainly refers to the transformation of white iron surface layer to gray cast iron and graphite separations appearance, which causes the crack primers and cracking corrosion phenomena in tools material.
Traditional risk stratification modestly predicts adverse cardiovascular events in patients with coronary artery disease (CAD). Our aim was to investigate the association between monocyte subsets ...numbers and function, and the first major adverse cardiovascular event (MACE) in patients with symptomatic stable CAD and angiographically documented coronary atherosclerosis.
Patients with stable CAD were screened for inclusion. Using flow cytometry, we identified classical, intermediate, and non-classical monocyte subsets and we assessed cytokine production capacity after ex-vivo stimulation of peripheral blood mononuclear cells. Clinical follow-up was performed after four years. The endpoint was the composite of cardiovascular death, acute myocardial infarction, and ischemic stroke.
A cohort of 229 patients was recruited. The percentage of intermediate monocytes was positively associated with adverse cardiovascular events at follow-up (HR 1.09; 95%CI 1.02–1.16; p = 0.006), while the percentage of classical monocytes was identified as a protective factor for adverse outcomes (HR 0.96; 95%CI 0.94–0.99; p = 0.02). The percentage of intermediate monocytes remained independently associated with outcomes after adjusting for age, systolic blood pressure, and left ventricular ejection fraction (HR 1.07; 95% CI 1.01–1.14; p = 0.04). Several correlations were identified between monocyte subsets and stimulated cytokine production, but cytokine production capacity was not associated with adverse outcomes.
In patients with stable CAD, intermediate monocytes were associated with MACE at follow-up. The association was not due to an increased cytokine production capacity. Novel biomarkers could improve risk stratification in patients with stable CAD and could represent new pharmacological targets against atherosclerosis progression.
•In stable CAD, intermediate monocytes are associated with an increased risk of MACE at four years follow-up.•The percentage of classical monocytes is a protective factor for adverse outcomes.•The association between monocyte subsets and MACE is independent of their cytokine production capacity.
This paper presents the results of the main changes in the chemical composition of the material, and changes in its hardness. The changes in terms of chemical composition refer primarily to changes ...in concentration of sulfur and carbon, and in terms of hardness material change there can be noticed a decrease in hardness of the material that is in direct contact with waste rubber.
Carbon nanotubes (CNTs) are emerging versatile tools in nanomedicine applications, particularly in the field of cancer targeting. Due to diverse surface chemistry and unique thermal properties, CNTs ...can act as strong optical absorbers in near infrared light where biological systems prove to be highly transparent. The process of laser-mediated ablation of cancer cells marked with biofunctionalized CNTs is frequently termed "nanophotothermolysis." This paper illustrates the potential of engineered CNTs as laser-activated photothermal agents for the selective nanophotothermolysis of cancer cells.
Doxorubicin (DOX) is a widely used chemotherapeutic drug for human hepatocellular carcinoma (HCC). A major limitation to its effectiveness is the development of multidrug resistance of cancer cells. ...In clinical trials, patients with advanced HCC were treated with high-dose acetaminophen (HAAP) in an effort to improve the antitumor activity of chemotherapeutics. In this study, we investigated the effect of concomitant treatment of DOX and HAAP on hepatoma-derived HepG2 cells. Viability, cell cycle distribution, and ultrastructure were examined. Unexpectedly, HAAP, when added to DOX-exposed cells, increased cell viability, released cell cycle arrest, and decreased apoptosis. To elucidate the mechanisms by which HAAP reduces the DOX lethal effect to HepG2 cells, we investigated the multidrug resistance P-glycoprotein (P-gp) and p44/42-mitogen-activated protein kinase (MAPK) pathways. The P-gp function was enhanced by DOX and HAAP, and it was further stimulated during combined treatment, leading to decreased DOX retention. Verapamil (VRP), when added to DOX + HAAP exposure, increased DOX accumulation and restored DOX-induced toxicity. The increased phospho-p44/42-MAPK level in DOX-exposed cells was inhibited by HAAP. In addition, suppression of p44/42 activation by the p44/42-MAPK inhibitor 2'-amino-3'-methoxyflavone (PD98059) blocked DOX-induced apoptosis. These findings suggest that the antagonistic effect of concomitant DOX + HAAP treatment occurs as a result of interactive stimulation of P-gp, generating decreased intracellular drug concentrations. Furthermore, inhibition of the p44/42-MAPK phosphorylation by HAAP could abolish the DOX-induced cell death pathway. Thus, combined treatment by DOX + HAAP, intended to improve chemotherapeutic efficacy, could have an opposite effect facilitating cancer cell survival.
: Acetaminophen in large doses is well‐known as hepatotoxic, and early therapy with N‐acetylcysteine is frequently life‐saving. However, in later stages of acetaminophen poisoning, treatment with ...N‐acetylcysteine is not always effective. Although some of the pathways of acetaminophen toxicity and the effect of N‐acetylcysteine have been elucidated, in depth information on this process is still lacking. Hepatoma‐derived HepG2 cultured cells were exposed to acetaminophen (5 and 10 mM), with or without N‐acetylcysteine (5 mM), for 24 and 48 hr. For the assessment of oxidative damage, apoptosis and necrosis, we followed redox status, glutathione content, nuclear fragmentation, phosphatidylserine externalization and ultrastructural changes. Variations in Ca2+ level and number of mitochondrial dense granules were also studied. Acetaminophen treatment of HepG2 cells caused oxidative damage and apoptosis. Significant decrease of cellular redox potential and glutathione content were time‐ and concentration‐dependent. The protective effect of N‐acetylcysteine was expressed by an increase of intracellular glutathione and of the level of metabolic reduction of the redox indicator Alamar Blue. The apoptogenic effect of acetaminophen was assessed by flow cytometry of annexin V binding, nuclear hypodiploidity, intracellular Ca2+, as well as by ultrastructural examination. Beyond 24 hr of acetaminophen exposure, necrosis was also noticed. We conclude that acetaminophen‐induced oxidative damage in HepG2 cultured cells can be prevented by exposure to N‐acetylcysteine. However, apoptosis, either early or late, here demonstrated, is not avoided by exposure to N‐acetylcysteine. N‐Acetylcysteine did not prevent acetaminophen‐induced plasma membrane asymmetry, nuclear damage, alterations of Ca2+ homeostasis and ultrastructural changes.
Mitochondrial respiratory chain disorders are an established cause of liver failure in early childhood. In some patients, the levels of mitochondrial DNA are markedly reduced, a condition referred to ...as mtDNA depletion syndrome (MDS). We report here on the ultrastructural changes in the livers of 10 infants with the hepatic form of this syndrome. All patients displayed progressive liver failure, neurological abnormalities, hypoglycemia, and lactic acidosis that warranted investigation of respiratory chain disorder in liver tissue, specifically expressing the disease. Decreased activity of respiratory chain complexes containing mtDNA-encoded subunits (complexes I, III, IV) was shown in 5 patients. Mitochondrial DNA depletion was confirmed by Southern blot analysis in the livers of 6 patients. We found hepatocytes filled with mitochondria having aspects of “oncocytic transformation,” associated with numerous changes in shape, size, cristae, and matrix. The changes were virtually identical in all specimens. In many hepatocytes, microvesicular steatosis was the salient feature. Additional findings included cholestasis and focal cytoplasmic biliary necrosis (CBN), as well as cytosiderosis in hepatocytes and sinusoidal cells. In some hepatocytes the damage appeared extreme, but fibrosis was identified only in the few patients who died beyond 6 months of age. Although individual ultrastructural findings are not specific, when taken together, they show a diagnostic pattern highly suggestive of a respiratory chain disorder. In the appropriate clinical context, these findings can direct the clinician towards the diagnosis of hepatic MDS. (H
EPATOLOGY 2001;34:776-784.)
Myeloproliferative neoplasms (MPNs) are clonal hematopoietic diseases that belong to the spectrum of myeloid malignancies (MyMs), which also include myelodysplastic syndromes (MDS), acute myeloid ...leukemia (AML), and chronic myelogenous leukemia (CML). While hematopoietic stem cell transplantation (HSCT) is a potentially curative therapeutic approach to many MyMs, the associated morbidity and mortality have necessitated the development of non-HSCT therapeutics for symptom management and disease course modification. Immune checkpoint inhibition, in particular along the programmed cell death protein 1 (PD-1)/B7-H1 (PD-L1) axis, is an established strategy in solid tumors with potential as an adjunctive therapy in hematologic malignancies. Seminal studies suggest that the pro-inflammatory microenvironment of MyMs can suppress T lymphocyte-mediated immunity via PD-1 signaling and that response to mainstay epigenetic therapies for MyMs may be governed by PD-1 gene regulation. Although the role of PD-1 signaling in MPN pathogenesis and progression is as yet unclear, research in MPN patients has revealed expansion of myeloid-derived suppressor cells (MDSCs), which may effect host immune tolerance of tumor via temporally and spatially specific activation of PD-1/PD-L1 signaling. The current understanding of immune dysfunction in MPNs and analogous MyMs offers a compelling rationale to study PD-1/PD-L1 inhibition in patients as a novel treatment option.
The passive transport of glucose and related hexoses in human cells is facilitated by members of the glucose transporter family (GLUT, SLC2 gene family). GLUT3 is a high-affinity glucose transporter ...primarily responsible for glucose entry in neurons. Changes in its expression have been implicated in neurodegenerative diseases and cancer. GLUT3 inhibitors can provide new ways to probe the pathophysiological role of GLUT3 and tackle GLUT3-dependent cancers. Through in silico screening of an ~ 8 million compounds library against the inward- and outward-facing models of GLUT3, we selected ~ 200 ligand candidates. These were tested for in vivo inhibition of GLUT3 expressed in hexose transporter-deficient yeast cells, resulting in six new GLUT3 inhibitors. Examining their specificity for GLUT1-5 revealed that the most potent GLUT3 inhibitor (G3iA, IC
~ 7 µM) was most selective for GLUT3, inhibiting less strongly only GLUT2 (IC
~ 29 µM). None of the GLUT3 inhibitors affected GLUT5, three inhibited GLUT1 with equal or twofold lower potency, and four showed comparable or two- to fivefold better inhibition of GLUT4. G3iD was a pan-Class 1 GLUT inhibitor with the highest preference for GLUT4 (IC
~ 3.9 µM). Given the prevalence of GLUT1 and GLUT3 overexpression in many cancers and multiple myeloma's reliance on GLUT4, these GLUT3 inhibitors may discriminately hinder glucose entry into various cancer cells, promising novel therapeutic avenues in oncology.
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