Long-Term Oral Administration of Theaphenon-E Improves Cardiomyocyte Mechanics and Calcium Dynamics by Affecting Phospholamban Phosphorylation and ATP Production

Background/Aims: Dietary polyphenols from green tea have been shown to possess cardio-protective activities in different experimental models of heart diseases and age-related ventricular dysfunction. The present study was aimed at evaluating whether long term in vivo administration of green tea extracts (GTE), can exert positive effects on the normal heart, with focus on the underlying mechanisms. Methods: The study population consisted of 20 male adult Wistar rats. Ten animals were given 40 mL/day tap water solution of GTE (concentration 0.3%) for 4 weeks (GTE group). The same volume of water was administered to the 10 remaining control rats (CTRL). Then, in vivo and ex vivo measurements of cardiac function were performed in the same animal, at the organ (hemodynamics) and cellular (cardiomyocyte mechanical properties and intracellular calcium dynamics) levels. On cardiomyocytes and myocardial tissue samples collected from the same in vivo studied animals, we evaluated: (1) the intracellular content of ATP, (2) the endogenous mitochondrial respiration, (3) the expression levels of the Sarcoplasmic Reticulum Ca2+-dependent ATPase 2a (SERCA2), the Phospholamban (PLB) and the phosphorylated form of PLB, the L-type Ca2+ channel, the Na+-Ca2+ exchanger, and the ryanodine receptor 2. Results: GTE cardiomyocytes exhibited a hyperdynamic contractility compared with CTRL (the rate of shortening and re-lengthening, the fraction of shortening, the amplitude of calcium transient, and the rate of cytosolic calcium removal were significantly increased). A faster isovolumic relaxation was also observed at the organ level. Consistent with functional data, we measured a significant increase in the intracellular ATP content supported by enhanced endogenous mitochondrial respiration in GTE cardiomyocytes, as well as higher values of the ratios phosphorylated-PLB/PLB and SERCA2/PLB. Conclusions: Long-term in vivo administration of GTE improves cell mechanical properties and intracellular calcium dynamics in normal cardiomyocytes, by increasing energy availability and removing the inhibitory effect of PLB on SERCA2

Evidence for folate-salvage reactions in plants

Folates in vivo undergo oxidative cleavage, giving pterin and p-aminobenzoylglutamate (pABAGlu) moieties. These breakdown products are excreted in animals, but their fate is unclear in microorganisms and unknown in plants. As indirect evidence from this and previous studies strongly suggests that plants can have high folate-breakdown rates (approximately 10% per day), salvage of the cleavage products seems likely. Four sets of observations support this possibility. First, cleavage products do not normally accumulate: pools of pABAGlu (including its polyglutamyl forms) are equivalent to, at most, 4-14% of typical total folate pools in Arabidopsis thaliana, Lycopersicon esculentum and Pisum sativum tissues. Pools of the pterin oxidation end-product pterin-6-carboxylate are, likewise, fairly small (3-37%) relative to total folate pools. Second, little pABAGlu built up in A. thaliana plantlets when net folate breakdown was induced by blocking folate synthesis with sulfanilamide. Third, A. thaliana and L. esculentum tissues readily converted supplied breakdown products to folate synthesis precursors: pABAGlu was hydrolysed to p-aminobenzoate and glutamate, and dihydropterin-6-aldehyde was reduced to 6-hydroxymethyldihydropterin. Fourth, both these reactions were detected in vitro; the reduction used NADPH as cofactor. An alternative salvage route for pABAGlu, direct reincorporation into dihydrofolate via the action of dihydropteroate synthase, appears implausible from the properties of this enzyme. We conclude that plants are excellent organisms in which to explore the biochemistry of folate salvage

Lemur tyrosine kinases and prostate cancer: A literature review

The members of the Lemur Tyrosine Kinases (LMTK1-3) subfamily constitute a group of three membrane-anchored kinases. They are known to influence a wide variety of key cellular events, often affecting cell proliferation and apoptosis. They have been discovered to be involved in cancer, in that they impact various signalling pathways that influence cell proliferation, migration, and invasiveness. Notably, in the context of genome-wide association studies, one member of the LMTK family has been identified as a candidate gene which could contribute to the development of prostate cancer. In this review, of published literature, we present evidence on the role of LMTKs in human prostate cancer and model systems, focusing on the complex network of interacting partners involved in signalling cascades that are frequently activated in prostate cancer malignancy. We speculate that the modulators of LMTK enzyme expression and activity would be of high clinical relevance for the design of innovative prostate cancer treatment

Flavonoids as epigenetic modulators for prostate cancer prevention

Prostate cancer (PCa) is a multifactorial disease with an unclear etiology. Due to its high prevalence, long latency, and slow progression, PCa is an ideal target for chemoprevention strategies. Many research studies have highlighted the positive effects of natural flavonoids on chronic diseases, including PCa. Different classes of dietary flavonoids exhibit anti-oxidative, anti-inflammatory, anti-mutagenic, anti-aging, cardioprotective, anti-viral/bacterial and anti-carcinogenic properties. We overviewed the most recent evidence of the antitumoral effects exerted by dietary flavonoids, with a special focus on their epigenetic action in PCa. Epigenetic alterations have been identified as key initiating events in several kinds of cancer. Many dietary flavonoids have been found to reverse DNA aberrations that promote neoplastic transformation, particularly for PCa. The epigenetic targets of the actions of flavonoids include oncogenes and tumor suppressor genes, indirectly controlled through the regulation of epigenetic enzymes such as DNA methyltransferase (DNMT), histone acetyltransferase (HAT), and histone deacetylase (HDAC). In addition, flavonoids were found capable of restoring miRNA and lncRNA expression that is altered during diseases. The optimization of the use of flavonoids as natural epigenetic modulators for chemoprevention and as a possible treatment of PCa and other kinds of cancers could represent a promising and valid strategy to inhibit carcinogenesis and fight cancer

Roles of Autophagy Induced by Natural Compounds in Prostate Cancer

Autophagy is a homeostatic mechanism through which intracellular organelles and proteins are degraded and recycled in response to increased metabolic demand or stress. Autophagy dysfunction is often associated with many diseases, including cancer. Because of its role in tumorigenesis, autophagy can represent a new therapeutic target for cancer treatment. Prostate cancer (PCa) is one of the most common cancers in aged men. The evidence on alterations of autophagy related genes and/or protein levels in PCa cells suggests a potential implication of autophagy in PCa onset and progression. The use of natural compounds, characterized by low toxicity to normal tissue associated with specific anticancer effects at physiological levels in vivo, is receiving increasing attention for prevention and/or treatment of PCa. Understanding the mechanism of action of these compounds could be crucial for the development of new therapeutic or chemopreventive options. In this review we focus on the current evidence showing the capacity of natural compounds to exert their action through autophagy modulation in PCa cells

Evidence for essential catalytic determinants for human erythrocyte pyrimidine 5′-nucleotidase

Human erythrocyte pyrimidine 5′-nucleotidase, PN-I, catalyzes the dephosphorylation of pyrimidine nucleoside monophosphates. The enzyme also possesses phosphotransferase activity, transferring phosphate groups between pyrimidine nucleoside monophosphates and various pyrimidine nucleosides. Deficiency of the enzyme activity is associated with a hemolytic anemia. PN-I cDNA has been expressed in Escherichia coli, yielding a fully active recombinant enzyme, which was purified to homogeneity and extensively characterized. Multiple sequence alignment of PN-I and homologues proteins revealed the existence of conserved regions, whose importance in catalysis was examined by performing experiments designed to intercept covalent intermediates as strongly suggested by our previous kinetic studies. Furthermore, a functional analysis of the enzyme was carried out through site-directed mutagenesis designed on the basis of the sequence of the identified conserved regions as well as mutations observed in PN-I-deficient patients. © Birkhäuser Verlag, 2005

Evidence for essential catalytic determinants for human erythrocytes pyrimidine 5’-nucleotidase

Human erythrocyte pyrimidine 5'-nucleotidase, PN-I, catalyzes the dephosphorylation of pyrimidine nucleoside monophosphates. The enzyme also possesses phosphotransferase activity, transferring phosphate groups between pyrimidine nucleoside monophosphates and various pyrimidine nucleosides. Deficiency of the enzyme activity is associated with a hemolytic anemia. PN-I cDNA has been expressed in Escherichia coli, yielding a fully active recombinant enzyme, which was purified to homogeneity and extensively characterized. Multiple sequence alignment of PN-I and homologues proteins revealed the existence of conserved regions, whose importance in catalysis was examined by performing experiments designed to intercept covalent intermediates as strongly suggested by our previous kinetic studies. Furthermore, a functional analysis of the enzyme was carried out through site-directed mutagenesis designed on the basis of the sequence of the identified conserved regions as well as mutations observed in PN-I-deficient patients