Blocking glutamate-mediated signalling inhibits human melanoma growth and migration.

Glutamate is an excitatory neurotransmitter that has been shown to regulate the proliferation, migration and survival of neuronal progenitors in the central nervous system through its action on metabotropic and ionotropic glutamate receptors (GluRs). Antagonists of ionotropic GluRs have been shown to cause a rapid and reversible change in melanocyte dendritic morphology, which is associated with the disorganization of actin and tubulin microfilaments in the cytoskeleton. Intracellular expression of microtubule-associated protein (MAP) 2a affects the assembly, stabilization and bundling of microtubules in melanoma cells; stimulates the development of dendrites; and suppresses melanoma cell migration and invasion. In this study, we investigated the relationship between glutamate-mediated signalling and microtubules, cell dendritic morphology and melanoma cell motility. We found that metabotropic GluR1 and N-methyl-d-aspartate receptor antagonists increased dendritic branching and inhibited the motility, migration and proliferation of melanoma cells. We also demonstrated that the invasion and motility of melanoma cells are significantly inhibited by the combination of increased expression of MAP2a and either metabotropic GluR1 or N-methyl-d-aspartate receptor antagonists. Moreover, the blockade of glutamate receptors inhibited melanoma growth in vivo. Collectively, these results demonstrate the importance of glutamate signalling in human melanoma and suggest that the blockade of glutamate receptors is a promising novel therapy for treating melanoma.

Blocking core fucosylation of TGF-ß1 receptors downregulates their functions and attenuates the epithelial-mesenchymal transition of renal tubular cells.

Posttranslational modification of proteins could regulate their multiple biological functions. Transforming growth factor-ß receptor I and II (ALK5 and TGF-ßRII), which are glycoproteins, play important roles in the renal tubular epithelial-mesenchymal transition (EMT). In the present study, we examined the role of core fucosylation of TGF-ßRII and ALK5, which is regulated by α-1,6 fucosyltransferase (Fut8), in the process of EMT of cultured human renal proximal tubular epithelial (HK-2) cells. The typical cell model of EMT induced by TGF-ß1 was constructed to address the role of core fucosylation in EMT. Core fucosylation was found to be essential for both TGF-ßRII and ALK5 to fulfill their functions, and blocking it with Fut8 small interfering RNA greatly reduced the phosphorylation of Smad2/3 protein, caused the inactivation of TGF-ß/Smad2/3 signaling, and resulted in remission of EMT. More importantly, even with high levels of expressions of TGF-ß1, TGF-ßRII, and ALK5, blocking core fucosylation also could attenuate the EMT of HK-2 cells. Thus blocking core fucosylation of TGF-ßRII and ALK5 may attenuate EMT independently of the expression of these proteins. This study may provide new insight into the role of glycosylation in renal interstitial fibrosis. Furthermore, core fucosylation may be a novel potential therapeutic target for treatment of renal tubular EMT.

[Advanced oxidation protein products promote expression of stromal-cell derived factor-1alpha of ECV304 cells through ERK signal pathway].

OBJECTIVE: To explore the effects of advanced oxidation protein products (AOPP) on expressions of stromal cell-derived factor-1alpha (SDF-1alpha) in ECV304 cells and the signal pathway that mediated the effects. METHODS: AOPP-BSA was made from bovine serum albumin (BSA) and sodium hypochlorite. After treated with AOPP-BSA of different concentrations (50, 100, 200 micromol/L), the expressions of SDF-1alpha mRNA in ECV304 cells were measured by reverse transcription-polymerase chain reaction (RT-PCR) and the expressions of SDF-1alpha protein and the levels of phosphorylated extracellular signal-regulated kinase (ERK) in ECV304 cells were analyzed by Western blot. In inhibition test, U0126, the special inhibitor of ERK of different concentrations (0.1, 1, 10 rmol/L) were added into ECV304 cells culture media for 1 hour, then the cells were treated with AOPP-BSA for 24 hours, at last the protein levels in supernatant were detected by enzyme-linked immunosorbent assay (ELISA). RESULTS: AOPP-BSA obviously promoted the expressions of SDF-1alpha mRNA and increased the levels of SDF-1beta protein of ECV304 cells in dose-dependent manner (all P < 0.01), after 15 minutes treated with 200 micromol/L AOPP-BSA, the levels of phosphorylated ERK of ECV304 cells increased significantly (P < 0.01). When the ERK pathway was blocked by U0126, the promoting effects of AOPP-BSA on expressions of SDF-la protein in ECV304 cells were significantly inhibited in dose-dependent manner (P < 0.05). CONCLUSION: AOPP induced the expression of SDF-la of ECV304 cells, ERK signal pathway is an important pathway that mediated the effects.

[Analysis of immunophenotypes of acute lymphoblastic leukemia by three color flow cytometry].

This study was purposed to investigate the immunophenotype characteristics and their significance in subtypes of acute lymphoblastic leukemia (ALL). The immunophenotypes in 40 cases of ALL were analyzed with three color flow cytometry using CD45/SSC two-parametric gating. The results showed that the three color flow cytometry assay using CD45/SSC two-parametric gating could accurately distinguish each other from lymphocytes, monocytes, granulocytes, erythroblasts and primitive cells in bone marrow and/or peripheral blood. Among 40 cases of ALL, B-ALL was 26 cases, T-ALL was 11 cases, HAL was 3 cases. All of the 26 cases of B-ALL expressed CD19 with positive rate of 100%, meanwhile 11 cases of T-ALL most highly expressed CD17 with positive rate of 100%. 12 cases of ALL with myeloid antigen expression (My-ALL) were involved in ALL, the incidence of these cases was almost 30% (12/40). The CD13 was expressed most highly in myeloid antigens. All 3 cases of HAL coexpressed myeloid and B-lineage antigens, among them CD34 was expressed in 2 cases with positive rate of 66.67%. It is concluded that three color flow cytometry assay using CD45/SSC two-parametric gating can exclude the interference of normal cells, thereby the results are more reliable and more accurate.

Dendroaspis natriuretic peptide relaxes gastric antral circular smooth muscle of guinea-pig through the cGMP/cGMP-dependent protein kinase pathway.

AIM: To systematically investigate if cGMP/cGMP-dependent protein kinase G (PKG) signaling pathway may participate in dendroaspis natriuretic peptide (DNP)-induced relaxation of gastric circular smooth muscle. METHODS: The content of cGMP in guinea pig gastric antral smooth muscle tissue and perfusion solution were measured using radioimmunoassay; spontaneous contraction of gastric antral circular muscles recorded using a 4-channel physiograph; and Ca(2+)-activated K(+) currents (I(K(Ca))) and spontaneous transient outward currents (STOCs) in isolated gastric antral myocytes were recorded using the whole-cell patch clamp technique. RESULTS: DNP markedly enhanced cGMP levels in gastric antral smooth muscle tissue and in the perfusion medium. DNP induced relaxation in gastric antral circular smooth muscle, which was inhibited by KT5823, a cGMP-dependent PKG inhibitor. DNP increased I(K(Ca)). This effect was almost completely blocked by KT5823, and partially blocked by LY83583, an inhibitor of guanylate cyclase to change the production of cGMP. DNP also increased STOCs. The effect of DNP on STOCs was abolished in the presence of KT5823, but not affected by KT-5720, a PKA-specific inhibitor. CONCLUSION: DNP activates I(K(Ca)) and relaxes guinea-pig gastric antral circular smooth muscle via the cGMP/PKG-dependent singling axis instead of cAMP/PKA pathway.

[Inhibition effect of antisense Bmi-1 on Jurkat cells].

OBJECTIVES: To investigate whether antisense Bmi-1 plasmid could inhibit the proliferation of Jurkat cells. METHODS: The antisense plasmid was constructed by PCR amplification of a 171 bp segment spanning Bmi-1 start codon and zinc finger structure and the PCR product was subsequently inserted reversely to plasmid pLNCX2. The final construct was confirmed through restriction enzyme digestion. G418 was added into the medium after the plasmid was successfully introduced into Jurkat cells by using lipofectin-mediated DNA transfection. The proliferation of Jurkat cells were determined by MTT and colony formation assays. Cell cycle was determined by flow cytometry. The p16 expression of Jurkat cells was studied by immunofluorescent histochemistry. RESULTS: The growth rate of antisense Bmi-1 transfected Jurkat cells was significantly lower than that of the controls, and the colony forming capacity of the transfected cells decreased significantly (P < 0.01), the colony numbers being (90.7 +/- 9.07)/10(3) cells, (83.3 +/- 6.11)/10(3) cells and (56.0 +/- 5.56)/10(3) cells for control cells, empty plasmid transfected Jurkat cells and antisense Bmi-1 transfected Jurkat cells, respectively. The percentage of G, phase cells was increased and the p16 expression of antisense Bmi-1 transfected cells was significantly upregulated than that of control cells. CONCLUSION: Antisense Bmi-1 can inhibit the growth and upregulate the expression of p16 of Jurkat cells in vitro.