Search

Cancer cells require substantial amounts of energy and substrates for their metabolic hyperactivity, enabling the synthesis of new cells at the expense of healthy ones. Preliminary in vitro data suggest that a mix of free essential amino acids (EAA-mix) can promote cancer cell apoptosis by enhancing autophagy. This study aimed to confirm, both in vitro and in vivo, whether EAA intake could influence the development of colon cancer in mice. We investigated changes in cancer proliferation in CT26 cells treated with EAA-mix and in mice fed with EAA-rich modified diets (EAARD) as compared to those on a standard laboratory diet (StD). CT26 cells were injected subcutaneously (s.c.) or intraperitoneally (i.p.). After 21 days, tumors were removed and measured. In vitro data corroborated that EAA-mix impairs cancer growth by inducing apoptosis. In vivo data revealed that mice on StD developed significantly larger (s.c.) and more numerous (i.p.) cancers than those on EAARD. EAA administration appears to influence cancer cell survival with notable antiproliferative properties.

Lead (Pb) is an environmental oncogenic metal that induces immunotoxicity and anaemia. Emerging evidence has linked Pb toxicity with endoplasmic reticulum-driven apoptosis and autophagy. Glucose-regulated protein of 78 kDa (Grp78 or binding immunoglobulin protein (BiP)), a master endoplasmic reticulum chaperone, drives macrophage activation and regulates protein folding and calcium flux in response to heavy metals. The spleen may be involved in Pb poisoning due to its crucial role in erythrocatheresis and immune response, although there are no data to support this theory. Here, we found haematic and histopathological changes in the spleen of mice exposed to medium doses of Pb acetate (200 ppm-1 mM) in drinking water for 45 days. Pb deposition was also detected in organs such as the liver, kidney, brain, bone, blood and faeces, indicating an accumulation of this metal despite relatively short exposure time. Blood Pb content (BBL) reached 21.6 μg/dL; echinocytes and poikilocytes were found in Pb smears of treated group. Inside the spleen, higher Fe(II) and Fe(III) deposits inside macrophages were observed. Grp78 immunostaining, weakly expressed in spleen cells of control mice, after Pb exposure was specifically restricted to macrophages and megakaryocytes of the marginal zone of red pulp. Furthermore, Pb exposure induced superoxide dismutase 1 (SOD1) expression, cleaved caspase-3 and p62/SQSTM1, consistent with oxidative stress, apoptosis and dysregulated autophagy in spleen compartments. We suggest that even at a middle dose, oral Pb intake induces oxidant iron deposition in the spleen and that this may trigger sustained Grp78 redistribution to cells, thus leading to oxidative and autophagy dysfunction as early local reactions to this dangerous metal.

Cancer cells require both energy and material to survive and duplicate in a competitive environment. Nutrients, such as amino acids (AAs), are not only a caloric source, but can also modulate cell metabolism and modify hormone homeostasis. Our hypothesis is that the environmental messages provided by AAs rule the dynamics of cancer cell life or death, and the alteration of the balance between essential amino acids (EAAs) and non-essential amino acids (NEAAs) (lower and higher than 50%, respectively) present in nutrients may represent a key instrument to alter environment-dependent messages, thus mastering cancer cells destiny. In this study, two AA mixtures, one exclusively consisting of EAAs and the other consisting of 85% EAAs and 15% NEAAs, were tested to explore their effects on the viability of both normal and cancer cell lines and to clarify the molecular mechanisms involved. Both mixtures exerted a cell-dependent anti-proliferative, cytotoxic effect involving the inhibition of proteasome activity and the consequent activation of autophagy and apoptosis. These results, besides further validating the notion of the peculiar interdependence and extensive crosstalk between the ubiquitin-proteasome system (UPS) and autophagy, indicate that variation in the ratio of EAAs and NEAAs can deeply influence cancer cell survival. Consequently, customization of dietary ratios among EAAs and NEAAs by specific AA mixtures may represent a promising anticancer strategy able to selectively induce death of cancer cells through the induction of apoptosis via both UPS inhibition and autophagy activation., (© 2017 Federation of European Biochemical Societies.)

We have previously demonstrated that STAT-1 plays a critical role in promoting apoptotic cell death in cardiac myocytes following ischemia/reperfusion (I/R) injury. Epigallocatechin-3-gallate (EGCG), the major constituent of green tea, has recently been reported to inhibit STAT-1 activity in noncardiac cells. In the present study, we have assessed the protective effects of EGCG and green tea extract (GTE) infusion on both cultures of cardiac myocytes and the isolated rat heart. EGCG reduced STAT-1 phosphorylation and protected cardiac myocytes against I/R-induced apoptotic cell death. Moreover, EGCG reduced the expression of a known STAT-1 pro-apoptotic target gene, Fas receptor. More interestingly, oral administration of GTE as well as EGCG infusion limited the extent of infarct size and attenuated the magnitude of myocyte apoptosis in the isolated rat heart exposed to I/R injury. This reduction cell death was associated with improved hemodynamic recovery and ventricular function in the ischemic/reperfused rat heart. This is the first report to show that consumption of green tea is able to mediate cardioprotection and enhance cardiac function during I/R injury. Because GTE-mediated cardioprotection is achieved, at least in part, through inhibition of STAT-1 activity, we may postulate that a similar action can be implemented in the clinical setting to minimize STAT-1 activation levels in patients with acute coronary artery disease (CAD).

Objectives: This study assesses the mechanisms of apoptosis in patients after on-pump coronary artery bypass graft surgery and the potential involvement of the endogenous cardiac peptide urocortin as a cardiomyocyte salvage mechanism. We have previously described the mechanisms of apoptosis after ischemia-reperfusion injury in the rat heart and shown that endogenous urocortin is cardioprotective. Here we extend these findings to the human heart exposed to ischemic-reperfusion injury., Methods: Two sequential biopsy specimens were obtained from the right atriums of 24 patients undergoing coronary artery bypass grafting at the start of grafting and 10 minutes after release of the aortic clamp. Apoptosis was identified by means of immunocytochemical colocalization between terminal deoxynucleotidyl transferase-mediated nick end-labeling positivity and active caspase-3. Immunostaining for active caspase-9 and caspase-8 was performed to identify the pathways of apoptosis induction. Urocortin and adenosine triphosphate-dependent potassium channel expression was also assessed by means of immunocytochemistry., Results: Myocyte apoptosis (<0.1% before coronary artery bypass grafting) was increased after coronary artery bypass grafting and reperfusion and was greater in patients with longer periods of cardioplegic arrest (3.3% +/- 0.5% with <55 minutes and 5.1% +/- 0.9% with 85-100 minutes, P <.001). Processing of caspase-9 was always more pronounced than that of caspase-8 (P <.05). Cardioplegic arrest was also associated with increased urocortin expression (up to 29% +/- 3.5% vs <3% in samples obtained before coronary artery bypass grafting, P <.001) but only in nonapoptotic myocytes. These and surrounding viable myocytes also showed increased Kir6.1 adenosine triphosphate-dependent potassium channel expression., Conclusions: Cardioplegic arrest and subsequent reperfusion result in cardiomyocyte apoptosis, largely through mitochondrial injury, as well as exclusive urocortin expression in viable cells. This finding might suggest a cardioprotective role for endogenous urocortin in human subjects.

Apoptosis contributes, with necrosis, to the cardiac cell loss after ischemia/reperfusion injury. The apoptotic cascade is initiated either by mitochondrial damage and activation of caspase-9 or by death receptor ligation and activation of caspase-8. In the present study, performed in the isolated rat heart exposed either to ischemia alone or ischemia followed by reperfusion, cleavage of caspase-9 was observed primarily in endothelial cells. Conversely, caspase-8 cleavage was only found in cardiomyocytes, where it progressively increased throughout reperfusion. Addition of a specific caspase-9 inhibitor to the perfusate before ischemia prevented endothelial apoptosis, whereas preischemic infusion of a specific caspase-8 inhibitor affected only myocyte apoptosis. Additionally, caspase-8-mediated BID processing was observed only during reperfusion. Production of tBID then sustains mitochondrial injury and perpetuates caspase-9 activation.

Abstract: Caffeine is the most frequently ingested neuroactive drug in the world and it is largely used to delay fatigue and improve physical activity. Caffeine can modulate NO synthesis in cells and may influence muscular function by modifying the cellular cycle life-death. There is little data concerning the relationship between caffeine in the heart, NOS expression and apoptosis and no data regarding the acute effect of high doses of caffeine in the in vivo myocardium. We therefore studied hemodynamic NOS and Bax/Bcl2 expression in the rat myocardium after a single cafffeine administration. Thirty-two male rats were divided into six groups: the first was iv-injected with caffeine (16mg/kg), the second with caffeine+ l-NAME (30mg/kg), the third with caffeine+ l-arg (0.5g/kg), the fourth with caffeine+ l-NAME+ l-arg and finally the fifth with saline. Mean arterial blood pressure (MAP) was monitored for 30min, then the animals were killed. The sixth group was injected with caffeine and killed after 2h. The hearts were isolated and processed by immunohistochemistry. We found that caffeine increased MAP temporarily while caffeine+ l-NAME increased it for a longer period. In the control myocardium, all NOS isoforms were expressed. The Bcl2 were strongly expressed inside the perinuclear cytoplasm whereas Bax was very faintly detectable in the peripheral cytoplasm. In caffeine and caffeine+ l-NAME treated animals, NOS expression disappeared. Bax and Bcl2 expression did not vary. The l-arg administration reversed these caffeine and l-NAME effects on NOS expression. Two hours after caffeine, NOS expression increased and Bax and Bcl2 expression did not vary, although Bcl2 was mainly expressed in the peripheral cytoplasm. We conclude that improved caffeine-induced physical performance could also be related to caffeine''s ability to interfere with endogenous myocardial NO synthesis. Furthermore, we suggest that myocardial cell plays an effective anti-apoptotic role against acute caffeine administration. [Copyright &y& Elsevier]

Abstract: Caffeine (Caf) is largely used to delay fatigue, improving physical activity. However, its role remains elusive, and there are no hemodynamic or immunohistochemical data regarding its effects on skeletal muscle. We studied the hemodynamic and NOS expression of Bax/Bcl2 in skeletal muscle after single Caf administration. Thirty-two male rats were divided into six groups: the first was iv-injected with Caf (16mg/kg), the second with Caf+L-NAME, the third with Caf+L-arg, the fourth with Caf+L-NAME+L-arg, fifth with saline. Mean arterial blood pressure (MAP) was monitored for 30′, then the animals were killed. The sixth group was injected with Caf and killed after 2h. The quadriceps were isolated and processed by immunohistochemistry. We found that Caf increased MAP temporarily, while Caf+L-NAME increased it for a longer period. In untreated muscle, all NOS isoforms was expressed with different intensity and localisation, and Bcl2 was strongly expressed among the myofibrils. In Caf and Caf+L-NAME treated animals, NOS expression was lost; Bcl2 expression decreased among myofibrils but increased inside the subsarcolemma. The L-arg administration reversed these Caf and L-NAME effects. Two hours after Caf, NOS expression increased. We concluded that improved physical performance could be related to Caf''s ability to interfere with the endogenous muscular synthesis of NO. [Copyright &y& Elsevier]

Energy production is the main task of the cancer cell metabolism because the costs of duplicating are enormous. Although energy is derived in cells by dismantling the carbon-to-carbon bonds of any macronutrient, cancer nutritional needs for energetic purposes have been studied primarily as being dependent on glycolysis. Since the end of the last century, the awareness of the dependence of cancer metabolism on amino acids not only for protein synthesis but also to match energy needs has grown. The roles of specific amino acids such as glutamine, glycine and serine have been explored in different experimental conditions and reviewed. Moreover, epidemiological evidence has revealed that some amino acids used as a supplement for therapeutic reasons, particularly the branched-chain ones, may reduce the incidence of liver cancer and a specific molecular mechanism has been proposed as functional to their protective action. By contrast and puzzling clinicians, the metabolomic signature of some pathologies connected to an increased risk of cancer, such as prolonged hyperinsulinemia in insulin-resistant patients, is identified by elevated plasma levels of the same branched-chain amino acids. Most recently, certain formulations of amino acids, deeply different from the amino acid compositions normally present in foods, have shown the power to master cancer cells epigenetically, slowing growth or driving cancer cells to apoptotic death, while being both beneficial for normal cell function and the animal's health and lifespan. In this review, we will analyze and try to disentangle some of the many knots dealing with the complexities of amino acid biology and links to cancer metabolism. [ABSTRACT FROM AUTHOR]