1,721,136 research outputs found
Atypical PKC-ζ and PKC-ι mediate opposing effects on MCF-7 Na+/K+ATPase activity
No full textWe demonstrated previously that in serum-starved MCF-7 breast cancer cell line, Ang II increased Na+/K(+)ATPase activity and activated the protein kinase C xi(PKC-xi) (Muscellaetal., 2002J Enclocrinol 173:315-323; 2003 J Cell Physiol 197:61 -68.). The aim of the present study was to investigate the modulation of the activity of the Na+/K(+)ATPase by PKC-xi in MCF-7 cells. Here, using serum-starved MCF-7cells, we have demonstrated that the effect of Ang II on the Na+/K(+)ATPase activity was inhibited by a synthetic myristoylated peptide with sequences based on the endogenous PKC-xi pseudosubstrate region (xi-PS) and by high doses of GF109203X, inhibitor of PKCs. When MCF-7 cells, grown in 10% fetal bovine serum (FBS), were stimulated with Ang II adose-and time-dependent inhibition of the Na+/K(+)ATPase activity was obtained. Under this growth condition we found that mRNAs for AT1, AT2, and for Na+/K(+)ATPase alpha(1) and alpha(3) subunits were unchanged; besides both the activity of the Na+/K(+)ATPase and the level of PKC-xi also were unaffected by the serum. The atypical PKC-xi level (present in very low abundance in serum-starved MCF-7) was increased and Ang II provoked its translocation from the cytosol to plasma membrane. PKC-xi was localized to the membrane, and upon Ang II treatment its cellular localization did not change. The Ang II-mediated decrease of the Na+/K(+)ATPase activity was inhibited by high doses of GF109203X but not by xi-PS, thus indicating that such effect was not due to PKC-xi activity. The treatment of cells with PKC-xi antisense oligodeoxynucleotides inhibited the effects of Ang II on the Na+/K(+)ATPase activity. Additionally, the effect of Ang II on Na+/K(+)ATPase activity was also blocked by the phosphatidylinositol 3-kinase (Pl3K) inhibitors, wortmannin and LY294002, and by the actin depolymerizing agents, cytochalasin D. In conclusion, in MCF-7 cells Ang II modulates the Na+/ K(+)ATPase activity by both atypical PKC-xi/-i. The effects of Ang II are opposite depending upon the presence of the serum-sensitive PKC-i, with the inhibitory effect possibly due to the redistribution of sodium pump from plasma membrane to the inactive intracellular pool
CCL20 induces migration and proliferation on breast epithelial cells
Full text linkThe communication between the tumor cells and the surrounding cells helps drive the process of tumor progression. Since the
microenvironment of breast cancer includes CCL20 chemokine, the purpose of this study was to determine whether CCL20 modulates the
physiology of healthy breast epithelial cells in areas adjacent to the tumor. Therefore, primary cultures of mammary cells taken from normal
peritumoral areaswere used.We assessed that breast cells expressedCCR6CCL20 receptor.Usingmolecular (siRNA) and pharmacological
(inhibitors) techniques, we found multiple signaling kinases to be activated by CCR6 and involved in CCL20-induced breast cell proliferation
and migration. The binding of 10 ng/ml CCL20 to CCR6 induced cell migration whilst higher concentrations (from 15 to 25 ng/ml) led to cell
proliferation. CCL20 controlled cell migration and MMP-9 expression by PKC-alpha that activated Src, which caused the activation of
downstream Akt, JNK, and NF-kB pathways. Furthermore, higher CCL20 concentrations increased cycE and decreased p27Kip expression
ending in enhanced cell proliferation.Cell proliferation occurred through PKC-epsilon activation that transactivated EGFR and ERK1/2/MAPK
pathway.Although activated by differentCCL20 concentrations, these pathways function in parallel and crosstalk to some extent, inasmuch as
Akt activation was responsible for ERK1/2 nuclear translocation and enhanced the transcription of of c-fos and c-myc, involved in cell
proliferation. In summary, tumor cells exchange signals with the surrounding healthy cellsmodifying the extracellular matrix through enzyme
secretion; thus, CCL20 might be a factor involved in the ontogeny of breast carcinoma
Purinergic receptors in a pleural mesotelioma cell line.
No full textWe here demonstrated the expression of 4 (P2Y1,4,6,11) purinoceptors mRNAs coupled to Gq protein. The extracellular ATP, UTP, ADP and UDP caused a transient [Ca2+]i peak followed by a sustained lower phase. Removal of extracellular Ca2+ decreased the initial transient and abolished the plateau phase. Ca2+ signal was blocked by the inhibitor of PLCβ, U73122. Through experiments of fluorescence quenching, it was seen that nucleotides increased plasmamembrane Ca2+ permeability. These results indicate that [Ca2+]i increase was due to activation of P2Y receptors exclusively and that Ca2+ is released from intracellular stores and also enters from the extracellular liquid. We also investigated the effects of purinoceptors on cell proliferation. UTP, ATP and UDP had no significant effects, while ADP causes a drastic cell proliferation decrease in a dose- and time-dependent manner. In conclusion, these results indicate that the expressed purinergic receptors act via PLC activation and that ADP may have a therapeutic potential in MM
PKC-zeta is required for angiotensin II-induced activation of ERK and synthesis of C-FOS in MCF-7 cells
No full textWe examined the signalling pathways responsible for the Ang II induction of growth in MCF-7 human breast cancer cells. Ang II in MCF-7 cells induced: (a) the translocation from the cytosol to membrane and nucleus of atypical protein kinase C-zeta (PKC-zeta) but not of PKC-alpha, -delta, -epsilon and -eta; (b) the expression of c-fos mRNA and protein; (c) the phosphorylation of the extracellular signal-regulated protein kinases 1 and 2 (ERK1/2). All these effects were due to the activation of the Ang II type I receptor (AT1) since they were blocked by the AT1 antagonist losartan. The Ang II-stimulated ERK1/2 phosphorylation was blocked by (a) high doses of staurosporine, inhibitor of PKC-zeta, and by a synthetic myristoylated peptide with sequences based on the endogenous PKC-zeta pseudosubstrate region (zeta-PS); (b) PD098059, a mitogen-activated protein kinase kinase inhibitor (MAPKK/MEK); and, moreover, (c) the inhibitors of phosphoinositide 3-kinases (PI3K), LY294002 and wortmannin, thus indicating that PI3K may act upstream of ERK1/2. The Ang II-evoked c-fos induction was blocked only by high doses of staurosporine and by zeta-PS whilst PD098059, LY294002 and wortmannin were ineffective, thus indicating that c-fos induction is not due to ERK1/2 activity. When the epidermal growth factor-receptor (FGFR) tyrosine kinase activity was inhibited by the use of its inhibitor AG1478, Ang II was still able to induce ERK1/2 phosphorylation and c-fos expression, therefore proving that the transactivation of EGFR was not required for these Ang 11 effects in MCF-7 cells. The previously reported proliferation of MCF-7 cells induced by Ang 11 was blocked by PD098059 and by wortmannin in a dose-dependent manner, thereby indicating that in MCF-7 cells the PI3K and ERK pathways mediate the mitogenic signalling of AT1. Our results suggest that in MCF-7 cells Ang 11 activates multiple signalling pathways involving PKC-zeta, PI3K and MAPK; of these pathways only PKC-zeta appears responsible for the induction of c-fos
Angiotensin II modulates the activity of the Na+/K+ATPase in eel kidney
No full textWe have previously shown that angiotensin II (Ang II) has a role at the level of the eel gill chloride cell regulating sodium balance, and therefore osmoregulation; the purpose of the present study was to extend these findings to another important osmoregulatory organ, the kidney.
By catalytic histochemistry Na+/K(+)ATPase activity was found in both sea water (SW)- and freshwater (FW)adapted eel kidney, particularly at the level of both proximal and distal tubules. Quantitation of tubular cell Na+/K(+)ATPase activity, by imaging, gave values in SW-adapted eels which were double those found in FW-adapted eels (Student's t-test: P 0.05 respectively). Isolated tubule cells stimulated with 100 nM Ang II showed a significant generation of inositol trisphosphate (InsP(3)) and an increment in calcium release from intracellular stores.
In conclusion, our results suggest that tubular Na+/K(+)ATPase is modulated by environmental salinity, and that Ang II has a role in regulating its activity in FW-adapted eels, probably through an InsP(3)-dependent mechanism
Angiotensin II modulates the activity of Na+/K+ATPase in cultured rat astrocytes via the AT1 receptor and protein kinase C-delta activation
No full textIn astrocytes the activity of the Na+,K+-ATPase pump maintains an inwardly directed electrochemical sodium gradient used by the Na+-dependent transporters and regulates the extracellular K+ concentration essential for neuronal excitability, We show here that incubation of cultured rat astrocytes with angiotensin II (Ang II) modulates Na+,K+-ATPase activity, in a dose-and time-dependent manner. Na+,K+-ATPase activation was mediated by binding of Ang II to AT1 receptors as it was completely blocked by DuP 753, a specific AT1 receptor subtype antagonist, Stimulation of Na+,K+-ATPase activity by Ang II was dependent on protein kinase C (PKC) activation because PKC antagonists abolished the inducing effect of Ang II and the PKC activator phorbol 12-myristate 13-acetate enhanced transporter activity, Ang II stimulated translocation of PKC-delta but not that of other PKC isoforms from the cytosol to the plasma membrane. These results indicate that the activity of Na+,K+-ATPase in astrocytes is increased by physiological concentrations of Ang II and that the AT1 receptor subtype mediates the Na+,K+-ATPase response to Ang II via PKC-delta activation
Angiotensin II does not stimulate proliferation of rat thyroid PC Cl3 cell line
No full textIn PC Cl3 cells, a rat thyroid cell line, angiotensin (Ang 11) activates the atypical protein kinase C-zeta (PKC-zeta) and the extracellular signal-regulated kinase (ERK) pathways. We here studied the Ang It effects on PC C13 cell proliferation. It was found that Ang 11: (1) induced the phosphorylation of protein kinase B (PKB), (2) induced the growth-related early gene c-fos expression, (3) enhanced the cyclin E and p27(kip) expression, (4) had no effects on Cdk2, and (5) did not affect the transition from G0/G1 to S phase. Inhibition of phosphoinositide-3kinase by LY294002 further increased the effect of Ang 11 on p27(kip) induction, whilst PKCs inhibition by GF109203X decreased such effect. The role of PKC-zeta was recognized by the use of a synthetic myristoylated peptide with sequences based on the endogenous PKC-zeta pseuclosubstrate and by PKC-zeta downregulation using the small interfering RNA (siRNA). Insulin had a replicating effect on PC C13 cells, induced the phosphorylation of PKB, decreased p27(kip) expression and had no effect on the PKC-zeta cytosol-to-membrane translocation. PC C13 cell proliferation was induced more potently by simultaneous stimulation with insulin and Ang 11 than by stimulation with insulin alone, and the effect on p27(kip) expression was similar to that obtained with insulin only. These observations demonstrate that in PC Cl3 cells Ang 11 causes a block in G1 phase, although both ERK and PKB pathways are activated, and this effect may be due to the upregulation of p27(kip) and PKC- operativity
Lactoferrin as an added-value whey component and a healthy additive in nutraceutical drinks.
No full text- …
