PAPOLA contributes to cyclin D1 mRNA alternative polyadenylation and promotes breast cancer cell proliferation

Poly(A) polymerases add the poly(A) tail at the 3' end of nearly all eukaryotic mRNA, and are associated with proliferation and cancer. To elucidate the role of the most-studied mammalian poly(A) polymerase, poly(A) polymerase α (PAPOLA), in cancer, we assessed its expression in 221 breast cancer samples and found it to correlate strongly with the aggressive triple-negative subtype. Silencing PAPOLA in MCF-7 and MDA-MB-231 breast cancer cells reduced proliferation and anchorage-independent growth by decreasing steady-state cyclin D1 (CCND1) mRNA and protein levels. Whereas the length of the CCND1 mRNA poly(A) tail was not affected, its 3' untranslated region (3'UTR) lengthened. Overexpressing PAPOLA caused CCND1 mRNA 3'UTR shortening with a concomitant increase in the amount of corresponding transcript and protein, resulting in growth arrest in MCF-7 cells and DNA damage in HEK-293 cells. Such overexpression of PAPOLA promoted proliferation in the p53 mutant MDA-MB-231 cells. Our data suggest that PAPOLA is a possible candidate target for the control of tumor growth that is mostly relevant to triple-negative tumors, a group characterized by PAPOLA overexpression and lack of alternative targeted therapies.

Exploring the crosstalk of glycolysis and mitochondrial metabolism in psychiatric disorders and brain tumours

Dysfunction of metabolic pathways characterises a plethora of common pathologies and has emerged as an underlying hallmark of disease phenotypes. Here, we focus on psychiatric disorders and brain tumours and explore changes in the interplay between glycolysis and mitochondrial energy metabolism in the brain. We discuss alterations in glycolysis versus core mitochondrial metabolic pathways, such as the tricarboxylic acid cycle and oxidative phosphorylation, in major psychiatric disorders and brain tumours. We investigate potential common patterns of altered mitochondrial metabolism in different brain regions and sample types and explore how changes in mitochondrial number, shape and morphology affect disease-related manifestations. We also highlight the potential of pharmacologically targeting mitochondria to achieve therapeutic effects.

mTORC2 deploys the mRNA binding protein IGF2BP1 to regulate c-MYC expression and promote cell survival

mTORC2 promotes cell survival by phosphorylating AKT and enhancing its activity. Inactivation of mTORC2 reduces viability through down-regulation of E2F1 caused by up-regulation of c-MYC. An additional target of mTORC2 is IGF2BP1, an oncofetal RNA binding protein expressed de novo in a wide array of malignancies. IGF2BP1 enhances c-MYC expression by protecting the coding region instability sequence (CRD) of its mRNA from endonucleolytic cleavage. Here we show that repression of mTORC2 signalling and prevention of Ser181 phosphorylation of IGF2BP1 enhanced translation and destabilization of the endogenous c-myc mRNA as well as the mRNA of reporter transcripts carrying the CRD sequence in frame. The consequent increase in c-MYC protein was accompanied by the emergence of an apoptotic c-MYC overexpressing population. On the other hand, preventing phosphorylation of IGF2BP1 on Tyr396 by Src kinase caused the accumulation of translationally silent transcripts through sequestration by IGF2BP1 into cytoplasmic granules. The apoptotic effect of mTORC2 signalling deprivation was augmented when preceded by inhibition of IGF2BP1 phosphorylation by the Src kinase in concert with further increase of c-MYC levels because of enhanced translation of the previously stored mRNA only in the presence of IGF2BP1. Furthermore, the combined administration of mTORC2 and Src inhibitors exhibited synergism in delaying xenograft growth in female NOD.CB17-Prkdc^scid/J mice. The above in vitro and in vivo findings may be applied for the induction of targeted apoptosis of cells expressing de novo the oncofetal protein IGF2BP1, a feature of aggressive malignancies resulting in a more focused anticancer therapeutic approach.

Recent Advances on the Anticancer Properties of Saffron (Crocus sativus L.) and Its Major Constituents

Cancer is the second leading cause of death globally with an estimated 9.6 million deaths in 2018 and a sustained rise in its incidence in both developing and developed countries. According to the WHO, about 1 in 6 deaths is due to cancer. Despite the emergence of many pioneer therapeutic options for patients with cancer, their efficacy is still time-limited and noncurative. Thus, continuous intensive screening for superior and safer drugs is still ongoing and has resulted in the detection of the anticancer properties of several phytochemicals. Among the spices, Crocus sativus L. (saffron) and its main constituents, crocin, crocetin, and safranal, have attracted the interest of the scientific community. Pharmacological experiments have established numerous beneficial properties for this brilliant reddish-orange dye derived from the flowers of a humble crocus family species. Studies in cultured human malignant cell lines and animal models have demonstrated the cancer prevention and antitumor activities of saffron and its main ingredients. This review provides an insight into the advances in research on the anticancer properties of saffron and its components, discussing preclinical data, clinical trials, and patents aiming to improve the pharmacological properties of saffron and its major ingredients.

Docosahexaenoic Acid Inhibits Proliferation of EoL-1 Leukemia Cells and Induces Cell Cycle Arrest and Cell Differentiation

Τhe effect of docosahexaenoic acid (DHA, an omega-3 polyunsaturated fatty acid) upon the proliferation of EoL-1 (Eosinophilic leukemia) cell line was assessed, while additional cellular events during the antiproliferative action were recorded. DHA inhibited EoL-1 cells growth dose-dependently by inducing growth arrest at G0/1 phase of the cell cycle. After DHA addition to the cells, the expression of MYC oncogene was decreased, PTAFR-mRNA overexpression was observed which was used as a marker of differentiation, and PLA2G4A-mRNA increase was recorded. The enzymatic activities of phospholipase A₂ (PLA₂), a group of hydrolytic enzymes, whose action precedes and leads to PAF biosynthesis through the remodeling pathway, as well as platelet activating factor acetylhydrolase (PAFAH) which hydrolyses and deactivates PAF, were also measured. DHA had an effect on the levels of both the intracellular and secreted activities of PLA₂ and PAFAH. The inflammatory cytokines IL-6 and TNF-α were also detected in high levels. In conclusion, DHA-induced EoL-1 cells differentiation was correlated with downregulation of MYC oncogene, overexpression of PTAFR and PLA2G4A-mRNAs, increase of the inflammatory cytokines production, and alteration of the enzymatic activities that regulate PAF levels. DHA is a natural substance and the understanding of its action on EoL-1 cells on molecular level could be useful in further investigation as a future therapeutic tool against F/P ⁺ hypereosinophilic syndrome.

Characterization of poly(ADP-ribose)--histone H1 complex formation in purified polynucleosomes and chromatin

Poly(ADP-ribose) [poly(ADP-Rib)] polymerase of HeLa nucleosomes has been shown in vitro, to catalyze the synthesis of a complex of histone H1 containing 2 H1 histones and 15-16 units of oligo(ADP-Rib). The synthesis of the H1 complex in vitro was compared in polynucleosome populations of various sizes (3--16 and greater than 30) released from HeLa nuclei following micrococcal nuclease digestion. Poly(ADP-Rib) was synthesized from [32P]NAD and the poly(ADP-ribosyl)ation of H1 was studied by selective H1 extraction, gel electrophoresis and autoradiography. Quantitative differences in H1 complex formation occurred when either chromatin concentration or polynucleosome length was varied. The data indicated that H1 complex formation in vitro was favored in polynucleosomes 16 nucleosomes long as compared to 8 nucleosomes. A series of partially ADP-ribosylated H1 species was also detected. Partially modified H1 species migrate more slowly than pure H1 in dodecylsulfate gels. The reduced mobility is a function of the number of attached ADP-Rib moieties. Thus, molecules containing one molecule of H1 and various numbers of ADP-Rib residues can be separated. When the partially modified H1 species were incubated in alkali to cleave the linkage of ADP-Rib to protein, (ADP-Rib1-15) were detected by chain length analysis on 15% polyacrylamide gels. The intermediate H1 species could be chased, in vitro, into as H1 complex with NAD and thus were determined to be successive precursors in the formation of the H1 complex. Evidence is presented that the H1 complex is synthesized in intact cells permeabilized with lysolecithin.