Assay for lipid peroxides in animal tissues by thiobarbituric acid reaction

Protein kinase C, an enzyme that is activated by the receptor-mediated hydrolysis of inositol phospholipids, relays information in the form of a variety of extracellular signals across the membrane to regulate many Ca2+-dependent processes. At an early phase of cellular responses, the enzyme appears to have a dual effect, providing positive forward as well as negative feedback controls over various steps of its own and other signaling pathways, such as the receptors that are coupled to inositol phospholipid hydrolysis and those of some growth factors. In biological systems, a positive signal is frequently followed by immediate negative feedback regulation. Such a novel role of this protein kinase system seems to give a logical basis for clarifying the biochemical mechanism of signal transduction, and to add a new dimension essential to our understanding of cell-to-cell communication.

https://science.sciencemag.org/content/sci/233/4761/305.full.pdf

Studies and perspectives of protein kinase C

Diversity and plasticity are hallmarks of cells of the monocyte-macrophage lineage. In response to IFNs, Toll-like receptor engagement, or IL-4/IL-13 signaling, macrophages undergo M1 (classical) or M2 (alternative) activation, which represent extremes of a continuum in a universe of activation states. Progress has now been made in defining the signaling pathways, transcriptional networks, and epigenetic mechanisms underlying M1-M2 or M2-like polarized activation. Functional skewing of mononuclear phagocytes occurs in vivo under physiological conditions (e.g., ontogenesis and pregnancy) and in pathology (allergic and chronic inflammation, tissue repair, infection, and cancer). However, in selected preclinical and clinical conditions, coexistence of cells in different activation states and unique or mixed phenotypes have been observed, a reflection of dynamic changes and complex tissue-derived signals. The identification of mechanisms and molecules associated with macrophage plasticity and polarized activation provides a basis for macrophage-centered diagnostic and therapeutic strategies.

/pdf/macrophage-plasticity-and-polarization-in-vivo-veritas-3j0n8qsu6m.pdf

Macrophage plasticity and polarization: in vivo veritas

Reactive oxygen species (ROS) homeostasis and redox regulation in cellular signaling

The clinical use of anthracyclines like doxorubicin and daunorubicin can be viewed as a sort of double-edged sword. On the one hand, anthracyclines play an undisputed key role in the treatment of many neoplastic diseases; on the other hand, chronic administration of anthracyclines induces cardiomyopathy and congestive heart failure usually refractory to common medications. Second-generation analogs like epirubicin or idarubicin exhibit improvements in their therapeutic index, but the risk of inducing cardiomyopathy is not abated. It is because of their janus behavior (activity in tumors vis-a-vis toxicity in cardiomyocytes) that anthracyclines continue to attract the interest of preclinical and clinical investigations despite their longer-than-40-year record of longevity. Here we review recent progresses that may serve as a framework for reappraising the activity and toxicity of anthracyclines on basic and clinical pharmacology grounds. We review 1) new aspects of anthracycline-induced DNA damage in cancer cells; 2) the role of iron and free radicals as causative factors of apoptosis or other forms of cardiac damage; 3) molecular mechanisms of cardiotoxic synergism between anthracyclines and other anticancer agents; 4) the pharmacologic rationale and clinical recommendations for using cardioprotectants while not interfering with tumor response; 5) the development of tumor-targeted anthracycline formulations; and 6) the designing of third-generation analogs and their assessment in preclinical or clinical settings. An overview of these issues confirms that anthracyclines remain "evergreen" drugs with broad clinical indications but have still an improvable therapeutic index.

/pdf/anthracyclines-molecular-advances-and-pharmacologic-4vygbx1i0b.pdf

Anthracyclines: Molecular Advances and Pharmacologic Developments in Antitumor Activity and Cardiotoxicity

Transferrin receptor induction by hypoxia. HIF-1-mediated transcriptional activation and cell-specific post-transcriptional regulation.

Iron metabolism in inflammation has been mostly characterized in macrophages exposed to pathogens or inflammatory conditions, mimicked by the combined action of LPS and IFN-gamma (M1 polarization) However, macrophages can undergo an alternative type of activation stimulated by Th2 cytokines, and acquire a role in cell growth and tissue repair control (M2 polarization) We characterized the expression of genes related to iron homeostasis in fully differentiated unpolarized (M0), M1 and M2 human macrophages The molecular signature of the M1 macrophages showed changes in gene expression (ferroportin repression and H ferritin induction) that favour iron sequestration in the reticuloendothelial system, a hallmark of inflammatory disorders, whereas the M2 macrophages had an expression profile (ferroportin upregulation and the downregulation of H ferritin and heme oxygenase) that enhanced iron release The conditioned media from M2 macrophages promoted cell proliferation more efficiently than those of M1 cells and the effect was blunted by iron chelation The role of ferroportin-mediated iron release was demonstrated by the absence of differences from the media of macrophages of a patient with loss of function ferroportin mutation The distinct regulation of iron homeostasis in M2 macrophages provides insights into their role under pathophysiological conditions

https://onlinelibrary.wiley.com/doi/pdf/10.1002/eji.200939889

Differential regulation of iron homeostasis during human macrophage polarized activation.

Induction of Ferritin Synthesis by Oxidative Stress TRANSCRIPTIONAL AND POST-TRANSCRIPTIONAL REGULATION BY EXPANSION OF THE “FREE” IRON POOL

The capacity of readily exchanging electrons makes iron not only essential for fundamental cell functions, but also a potential catalyst for chemical reactions involving free-radical formation and subsequent oxidative stress and cell damage. Cellular iron levels are therefore carefully regulated in order to maintain an adequate substrate while also minimizing the pool of potentially toxic ‘free iron’. Iron homoeostasis is controlled through several genes, an increasing number of which have been found to contain non-coding sequences [i.e. the iron-responsive elements (IREs)] which are recognized at the mRNA level by two cytoplasmic iron-regulatory proteins (IRP-1 and IRP-2). The IRPs belong to the aconitase superfamily. By means of an Fe-S-cluster-dependent switch, IRP-1 can function as an mRNA-binding protein or as an enzyme that converts citrate into isocitrate. Although structurally and functionally similar to IRP-1, IRP-2 does not seem to assemble a cluster nor to possess aconitase activity; moreover, it has a distinct pattern of tissue expression and is modulated by means of proteasome-mediated degradation. In response to fluctuations in the level of the ‘labile iron pool’, IRPs act as key regulators of cellular iron homoeostasis as a result of the translational control of the expression of a number of iron metabolism-related genes. Conversely, various agents and conditions may affect IRP activity, thereby modulating iron and oxygen radical levels in different pathobiological settings. As the number of mRNAs regulated through IRE–IRP interactions keeps growing, the definition of IRPs as iron-regulatory proteins may in the near future become limiting as their role expands to other essential metabolic pathways.

/pdf/iron-regulatory-proteins-in-pathobiology-1cgeuj69am.pdf

Gaetano Cairo

Papers

Anthracyclines: Molecular Advances and Pharmacologic Developments in Antitumor Activity and Cardiotoxicity

Transferrin receptor induction by hypoxia. HIF-1-mediated transcriptional activation and cell-specific post-transcriptional regulation.

Differential regulation of iron homeostasis during human macrophage polarized activation.

Induction of Ferritin Synthesis by Oxidative Stress TRANSCRIPTIONAL AND POST-TRANSCRIPTIONAL REGULATION BY EXPANSION OF THE “FREE” IRON POOL

Iron regulatory proteins in pathobiology.