Leucine-rich repeat protein PRAME: expression, potential functions and clinical implications for leukaemia

PRAME/MAPE/OIP4 is a germinal tissue-specific gene that is also expressed at high levels in haematological malignancies and solid tumours. The physiological functions of PRAME in normal and tumour cells are unknown, although a role in the regulation of retinoic acid signalling has been proposed. Sequence homology and structural predictions suggest that PRAME is related to the leucine-rich repeat (LRR) family of proteins, which have diverse functions. Here we review the current knowledge of the structure/function of PRAME and its relevance in leukaemia

eIF4A Inhibition Allows Translational Regulation of mRNAs Encoding Proteins Involved in Alzheimer's Disease

Alzheimer's disease (AD) is the main cause of dementia in our increasingly aging population. The debilitating cognitive and behavioral symptoms characteristic of AD make it an extremely distressing illness for patients and carers. Although drugs have been developed to treat AD symptoms and to slow disease progression, there is currently no cure. The incidence of AD is predicted to increase to over one hundred million by 2050, placing a heavy burden on communities and economies, and making the development of effective therapies an urgent priority. Two proteins are thought to have major contributory roles in AD: the microtubule associated protein tau, also known as MAPT; and the amyloid-beta peptide (A-beta), a cleavage product of amyloid precursor protein (APP). Oxidative stress is also implicated in AD pathology from an early stage. By targeting eIF4A, an RNA helicase involved in translation initiation, the synthesis of APP and tau, but not neuroprotective proteins, can be simultaneously and specifically reduced, representing a novel avenue for AD intervention. We also show that protection from oxidative stress is increased upon eIF4A inhibition. We demonstrate that the reduction of these proteins is not due to changes in mRNA levels or increased protein degradation, but is a consequence of translational repression conferred by inhibition of the helicase activity of eIF4A. Inhibition of eIF4A selectively and simultaneously modulates the synthesis of proteins involved in Alzheimer's disease: reducing A-beta and tau synthesis, while increasing proteins predicted to be neuroprotective

The human insulin receptor mRNA contains a functional internal ribosome entry segment.

Regulation of mRNA translation is an important mechanism determining the level of expression of proteins in eukaryotic cells. Translation is most commonly initiated by cap-dependent scanning, but many eukaryotic mRNAs contain internal ribosome entry segments (IRESs), providing an alternative means of initiation capable of independent regulation. Here, we show by using dicistronic luciferase reporter vectors that the 5'-UTR of the mRNA encoding human insulin receptor (hIR) contains a functional IRES. RNAi-mediated knockdown showed that the protein PTB was required for maximum IRES activity. Electrophoretic mobility shift assays confirmed that PTB1, PTB2 and nPTB, but not unr or PTB4, bound to hIR mRNA, and deletion mapping implicated a CCU motif 448 nt upstream of the initiator AUG in PTB binding. The IR-IRES was functional in a number of cell lines, and most active in cells of neuronal origin, as assessed by luciferase reporter assays. The IRES was more active in confluent than sub-confluent cells, but activity did not change during differentiation of 3T3-L1 fibroblasts to adipocytes. IRES activity was stimulated by insulin in sub-confluent cells. The IRES may function to maintain expression of IR protein in tissues such as the brain where mRNA translation by cap-dependent scanning is less effective

Cytotoxic potential of ethanol extract of Parquetina nigrescens on MCF-7, C4-2WT, HT 29 and HTC 116 cell lines

The cytotoxic activity of ethanol extract of Parquetina nigrescen was investigated using a (3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, methylene blue and Trypan Blue exclusion assay on four human cancer cell lines, MCF-7, HT 29, HTC 116 and C4-2WT. A mitochondrial enzyme in living cells, succinate-dehydrogenase cleaves the tetrazolium ring and converts the MTT to an insoluble purple formazan whose intensity is directly proportional to the presence of viable cells in the microwell plate. Results showed a significant (p less than 0.05) cytotoxic effect of the extract in a dose dependent manner. Cytotoxicity increased with increase in the concentration of the extract used. GI50 results calculated after MTT test showed the concentration of ethanol extract of P. nigrescens required for 50% inhibition of the different cell lines as follows: MCF-7 = 2.61 µg/ml, C4-2WT = 8.33 µg/ml, HCT 29 = 3.47 µg/ml and HCT 116 =1.75 µg/ml. For the methylene blue assay, the number of viable cells present was significantly reduced (p less than 0.05) with an increase in the concentration of the extract and duration of exposure of the cells to the extract. The result of trypan blue assay showed a significant reduction (p less than 0.05) in the total count of viable cells and a significant increase (p less than 0.05) in the total count of non-viable cells over 72 h post-treatment with an extract of P. nigrescens. Comparatively, results obtained indicate that there is a correlation between the various methods adopted in establishing the antiproliferative and cytotoxic activity of ethanol extract of P. nigrescens obtained in this study

Polymorphisms in NF-κB Inhibitors and Risk of Epithelial Ovarian Cancer

<p>Abstract</p> <p>Background</p> <p>The nuclear factor-κB (NF-κB) family is a set of transcription factors with key roles in the induction of the inflammatory response and may be the link between inflammation and cancer development. This pathway has been shown to influence ovarian epithelial tissue repair. Inhibitors of κB (IκB) prevent NF-κB activation by sequestering NF-κB proteins in the cytoplasm until IκB proteins are phosphorylated and degraded.</p> <p>Methods</p> <p>We used a case-control study to evaluate the association between single nucleotide polymorphisms (SNPs) in <it>NFKBIA </it>and <it>NFKBIB </it>(the genes encoding IκBα and IκBβ, respectively) and risk of epithelial ovarian cancer. We queried 19 tagSNPs and putative-functional SNPs among 930 epithelial ovarian cancer cases and 1,037 controls from two studies.</p> <p>Results</p> <p>The minor allele for one synonymous SNP in <it>NFKBIA</it>, rs1957106, was associated with decreased risk (p = 0.03).</p> <p>Conclusion</p> <p>Considering the number of single-SNP tests performed and null gene-level results, we conclude that <it>NFKBIA </it>and <it>NFKBIB </it>are not likely to harbor ovarian cancer risk alleles. Due to its biological significance in ovarian cancer, additional genes encoding NF-κB subunits, activating and inhibiting molecules, and signaling molecules warrant interrogation.</p

Translational regulation of gene expression during conditions of cell stress

A number of stresses, including nutrient stress, temperature shock, DNA damage, and hypoxia, can lead to changes in gene expression patterns caused by a general shutdown and reprogramming of protein synthesis. Each of these stress conditions results in selective recruitment of ribosomes to mRNAs whose protein products are required for responding to stress. This recruitment is regulated by elements within the 5′ and 3′ untranslated regions of mRNAs, including internal ribosome entry segments, upstream open reading frames, and microRNA target sites. These elements can act singly or in combination and are themselves regulated by trans-acting factors. Translational reprogramming can result in increased life span, and conversely, deregulation of these translation pathways is associated with disease including cancer and diabetes

Antiproliferative activities of some selected Nigerian medicinal plants against breast, liver, and cervical cancer cells

Abstract Background Phytochemicals have become a growing source of alternative medicine in developing countries due to the poor prognosis, high cost of conventional pharmaceuticals, and undesirable effects associated with mainstream cancer treatment. Objective This study was aimed at investigating the anticancer effect of some selected Nigerian medicinal plants used in cancer treatment. These include ethanol extracts of Dialium guineense root (DGR), Dialium guineense leaves (DGL), Jateorhiza macrantha leaves (JML), Musanga cecropioides leaves (MCL), Musanga cecropioides stembark (MCSB), Piptadeniastrum africanum stembark (PASB), Piptadeniastrum africanum root (PAR), Pupalia lappacea flower tops (PLF), Raphiostylis beninensis root (RBR), Raphiostylis beninensis leaves (RBL), Ritchiea capparoides leaves (RCL), Ritchiea capparoides stembark (RCSB), and Triplochiton scleroxylon stembark (TSB). Methods The cytotoxic activity of the extracts was examined using a brine shrimp lethality assay and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay against three cancer cell lines, including MCF-7, HUH-7, and HeLa. The selectivity of all extracts towards cancer cells was investigated using normal lung fibroblasts (MRC-5). Cell migration and colony-forming assays of active extracts against MCF-7 cells were also performed. Additionally, the total polyphenolic contents of the active extracts were estimated using standard methods. Results The extract of PASB had the highest cytotoxicity (LC50 = 1.58 μg/mL) on the brine shrimps compared to vincristine sulphate (LC50 = 2.24 μg/mL). In the cell viability assay, all the extracts produced significant (p < 0.05) growth inhibitory effects against all cell lines tested in a dose-dependent manner. All extracts were selective to cancer cells at varying degrees. Worth mentioning are the extracts of MCL, DGR, RBR, and PASB, which exhibited 14-, 7-, 6- and 2-fold selectivity toward MCF-7 cancer cells relative to normal lung fibroblast (MRC-5), respectively. These four extracts also significantly inhibited cell migration and colony formation in MCF-7-treated cells in dose-dependent manners. Considerable amounts of phenolics, flavonoids, and proanthocyanidins were detected in all extracts evaluated. Conclusion These findings advocate the continued development of MCL, DGR, RBR, and PASB as potential chemotherapeutic agents

SF2/ASF TORCs up translation

No abstract available

Polypyrimidine-tract-binding protein: a multifunctional RNA-binding protein

PTB (polypyrimidine-tract-binding protein) is a ubiquitous RNA-binding protein. It was originally identified as a protein with a role in splicing but it is now known to function in a large number of diverse cellular processes including polyadenylation, mRNA stability and translation initiation. Specificity of PTB function is achieved by a combination of changes in the cellular localization of this protein (its ability to shuttle from the nucleus to the cytoplasm is tightly controlled) and its interaction with additional proteins. These differences in location and trans-acting factor requirements account for the fact that PTB acts both as a suppressor of splicing and an activator of translation. In the latter case, the role of PTB in translation has been studied extensively and it appears that this protein is required for an alternative form of translation initiation that is mediated by a large RNA structural element termed an IRES (internal ribosome entry site) that allows the synthesis of picornaviral proteins and cellular proteins that function to control cell growth and cell death. In the present review, we discuss how PTB regulates these disparate processes

Re-programming of translation following cell stress allows IRES-mediated translation to predominate

There is now an overwhelming body of evidence to suggest that internal ribosome entry is required to maintain the expression of specific proteins during patho‐physiological situations when cap‐dependent translation is compromised, for example, following heat shock or during mitosis, hypoxia, differentiation and apoptosis. Translational profiling has been used by several groups to assess the extent to which alternative mechanisms of translation initiation selectively recruit mRNAs to polysomes during cell stress. The data from these studies have shown that under each condition 3–5% of coding mRNAs remain associated with the polysomes. Importantly, the genes identified in each of these studies do not show a significant amount of overlap, suggesting that 10–15% of all mRNAs have the capability for their initiation to occur via alternative mechanism(s)