Protein tyrosine phosphatases (PTPases) play an important role in regulating cell growth and transformation. We report that the antitumor agent gallium nitrate is a potent inhibitor (concentration producing 50% inhibition, 2-6 microM) of detergent-solubilized cellular membrane PTPase from Jurkat human T-cell leukemia cells and HT-29 human colon cancer cells. This is the first report of a select...

The expression of many genes is modulated after exposure to ionizing radiation. Identification of specific genes may allow the determination of pathways important in radiation responses. We previously identified modulation of the expression of several genes in response to ionizing radiation treatment. In the present study, we monitored the expression of RGS1, CC3, THBS1, vWF, MADH7, and a novel...

Charged multivesicular body protein 5 (CHMP5) has a key role in multivesicular body biogenesis and a critical role in the downregulation of signaling pathways through receptor degradation. However, the role of CHMP5 in T-cell receptor (TCR)-mediated signaling has not been previously investigated. In this study, we utilized a short hairpin RNA-based RNA interference approach to investigate the f...

We have recently reported that methionine adenosyltransferase (MAT) in resting human peripheral blood T-cells is primarily present in the form of a precursor which we named lambda. This protein decreases upon cell stimulation, as both MAT activity and the amount of the catalytic alpha/alpha' subunits of the enzyme increase. When resting cells are activated by phytohemagglutinin, the decrease in...

Triumfetta welwitschii is a plant used traditionally for the treatment of fever and diarrhoea. Previous work has shown that T. welwitschii has antibacterial activity. The purpose of this study was to investigate T. welwitschii extract for anticancer activity against Jurkat T cells. The Jurkat T cell line is used to study acute T cell leukaemia. An antiproliferation assay, determination of induc...

alpha-Hydroxy-9-cis-octadecenoic acid, a synthetic fatty acid that modifies the composition and structure of lipid membranes. 2-Hydroxyoleic acid (HOA) generated interest due to its potent, yet nontoxic, anticancer activity. It induces cell cycle arrest in human lung cancer (A549) cells and apoptosis in human leukemia (Jurkat) cells. These two pathways may explain how HOA induces regression of ...

Marsdenia tenacissimae extraction (MTE) as a traditional Chinese herb has long been used to treat some diseases such as tumors in China. However, the potential effectiveness of MTE in leukemia has not yet been fully understood, and the related molecular mechanism is still unknown. In the present study, we aimed to evaluate the effects of MTE on the proliferation and apoptosis of Jurkat cells (T...

Op18/stathmin (Op18), a conserved microtubule-depolymerizing and tubulin heterodimer-binding protein, is a major interphase regulator of tubulin monomer-polymer partitioning in diverse cell types in which Op18 is abundant. Here, we addressed the question of whether the microtubule regulatory function of Op18 includes regulation of tubulin heterodimer synthesis. We used two human cell model syst...

Ecto-phosphorylation plays an important role in many cellular functions. The transmembrane glycoprotein CD98 contains potential phosphorylation sites in its extracellular C-terminal tail. We hypothesized that extracellular signaling through ecto-protein kinases (ePKs) might lead to ecto-phosphorylation of CD98 and influence its multiple functions, including its role in cell-cell interactions. O...