Publications (34) View all
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Article: Proteolytic cleavage and truncation of NDRG1 in human prostate cancer cells, but not normal prostate epithelial cells.
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ABSTRACT: N-myc downstream regulated gene-1 (NDRG1) is a metastasis suppressor that is down-regulated in prostate cancer. NDRG1 phosphorylation is associated with inhibition of metastasis and western blots indicate two bands at ~41 and ~46 kDa. Previous investigations by others suggest the higher band is due to NDRG1 phosphorylation. However, the current study using a dephosphorylation assay and the Phos-tag SDS-PAGE assay, demonstrated the 46 kDa NDRG1 protein band was not due to phosphorylation. Further experiments showed the NDRG1 protein bands were not affected upon glycosidase treatment, despite marked effects of these enzymes on the glycosylated protein, fetuin. Analysis using RT-PCR demonstrated only a single amplicon, and thus, the two bands could not a result from an alternatively spliced NDRG1 transcript. Western blot analysis of prostate cancer cell lysates identified the 41 kDa band to be a truncated form of NDRG1, with mass spectrometry confirming the full and truncated proteins to be NDRG1. Significantly, this truncated protein was not present in normal human prostate epithelial cells. Western blot analysis using anti-NDRG1 raised to its N-terminal sequence failed to detect the truncated protein, suggesting it lacked N-terminus amino acids (residues 1-49). Sequence analysis predicted a pseudotrypsin protease cleavage site between Cys49-Gly50. Such cleavage of NDRG1 in cancer cells may result in loss of NDRG1 tumour suppressive activity.Bioscience Reports 05/2013; · 2.38 Impact Factor -
Article: Cytosolic phospholipase A2α sustains pAKT, pERK and AR levels in PTEN-null/mutated prostate cancer cells.
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ABSTRACT: Constitutive phosphorylation of protein kinase B (AKT) is a common feature of cancer caused by genetic alteration in the phosphatase and tensin homolog (PTEN) gene and is associated with poor prognosis. This study determined the role of cytosolic phospholipase A2α (cPLA2α) in AKT, extracellular signal-regulated kinase (ERK) and androgen receptor (AR) signaling in PTEN-null/mutated prostate cancer cells. Doxycycline (Dox)-induced expression of cPLA2α led to an increase in pAKT, pGSK3β and cyclin D1 levels in LNCaP cells that possess a PTEN frame-shift mutation. In contrast, silencing cPLA2α expression with siRNA decreased pAKT, pGSK3β and cyclin D1 levels in both PC-3 (PTEN deletion) and LNCaP cells. Silencing of cPLA2α decreased pERK and AR protein levels. The inhibitory effect of cPLA2α siRNA on pAKT and AR protein levels was reduced by the addition of arachidonic acid (AA), whereas the stimulatory effect of AA on pAKT, pERK and AR levels was decreased by an inhibitor of 5-hydroxyeicosatetraenoic acid production. Pharmacological blockade of cPLA2α with Efipladib reduced pAKT and AR levels with a concomitant inhibition of PC-3 and LNCaP cell proliferation. These results demonstrate an important role for cPLA2α in sustaining AKT, ERK and AR signaling in PTEN-null/mutated prostate cancer cells and provide a potential molecular target for treating prostate cancer.Biochimica et Biophysica Acta 03/2013; · 4.66 Impact Factor -
Dataset: Review in Patent
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Article: Quantitative reverse transcriptase polymerase chain reaction assay for mouse androgen receptor mRNA
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ABSTRACT: A quantitative reverse transcriptase polymerase chain reaction (RT-PCR) assay for mouse androgen receptor (AR) mRNA was developed to study relative changes in AR gene expression. Serial dilutions of a standard comprising a fragment of the ampicillin resistance gene flanked by the primer sequences of the AR mRNA were added to a constant amount of total RNA for RT-PCR. Primers were designed to generate a 541-bp fragment of mouse AR mRNA (target [T]) and a 460-bp fragment of the standard (S). PCR products were resolved by gel electrophoresis and quantitated by densitometry. A standard curve was generated for each sample by plotting the logarithm of T/S products vs the logarithm of the amount of S added. The amount of T was determined from the standard curve where intensities of PCR products of T and S were equal. The assay was validated by measuring the relative abundance of AR mRNA in 10 mouse tissues, and results were consistent with studies of AR expression in rat tissues. Assay reproducibility, tested by repeating assays on four different tissues on different days from the RT step, had a coefficient of variation of 6–16%. The current assay is thus both reproducible and valid in quantitation of mouse AR mRNA.Endocrine 04/2012; 15(2):193-198. · 1.42 Impact Factor -
Article: How can food extracts consumed in the Mediterranean and East Asia suppress prostate cancer proliferation?
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ABSTRACT: We have developed a blend of food extracts commonly consumed in the Mediterranean and East Asia, named blueberry punch (BBP), with the ultimate aim to formulate a chemoprevention strategy to inhibit prostate cancer progression in men on active surveillance protocol. We demonstrated previously that BBP inhibited prostate cancer cell proliferation in vitro and in vivo. The purpose of this study was to determine the molecular mechanism responsible for the suppression of prostate cancer cell proliferation by BBP. Treatment of lymph node-metastasised prostate cancer cells (LNCaP) and bone-metastasised prostate cancer cells (PC-3 and MDA-PCa-2b) with BBP (up to 0·8 %) for 72 h increased the percentage of cells at the G0/G1 phase and decreased those at the S and G2/M phases. The finding was supported by the reduction in the percentage of Ki-67-positive cells and of DNA synthesis measured by the incorporation of 5-ethynyl-2'-deoxyuridine. Concomitantly, BBP treatment decreased the protein levels of phosphorylated retinoblastoma, cyclin D1 and E, cyclin-dependent kinase (CDK) 4 and 2, and pre-replication complex (CDC6 and MCM7) in LNCaP and PC-3 cells, whereas CDK inhibitor p27 was elevated in these cell lines. In conclusion, BBP exerts its anti-proliferative effect on prostate cancer cells by modulating the expression and phosphorylation of multiple regulatory proteins essential for cell proliferation.The British journal of nutrition 11/2011; 108(3):424-30. · 3.45 Impact Factor
