Showing papers by "V. Wee Yong published in 2000"

Central Nervous System-Initiated Inflammation and Neurotrophism in Trauma: IL-1β Is Required for the Production of Ciliary Neurotrophic Factor

Abstract: Injury to the CNS results in the production and accumulation of inflammatory cytokines within this tissue. The origin and role of inflammation within the CNS remains controversial. In this paper we demonstrate that an acute trauma to the mouse brain results in the rapid elevation of IL-1β. This increase is detectable by 15 min after injury and significantly precedes the influx of leukocytes that occurs hours after. To confirm that IL-1β up-regulation is initiated by cells within the CNS, in situ hybridization for cytokine transcript was combined with cell type immunohistochemistry. The results reveal parenchymal microglia to be the sole source of IL-1β at 3 h postinjury. A role for CNS-initiated inflammation was addressed by examining the expression of the neurotrophic factor, ciliary neurotrophic factor (CNTF). Analysis of their temporal relationship suggests the up-regulation of CNTF by IL-1β, which was confirmed through three lines of evidence. First, the application of IL-1 receptor antagonist into the lesion site attenuated the up-regulation of CNTF. Second, the examination of corticectomized animals genetically deficient for IL-1β found no CNTF up-regulation. Third, the lack of CNTF elevation in IL-1β null mice was rescued through exogenous application of IL-1β into the lesion site. These findings provide the first evidence of the requirement for IL-1β in the production of CNTF following CNS trauma, and suggest that inflammation can have a beneficial impact on the regenerative capacity of the CNS.

Interleukin-1 is a key regulator of matrix metalloproteinase-9 expression in human neurons in culture and following mouse brain trauma in vivo

Abstract: An acute trauma to the CNS rapidly results in the upregulation of inflammatory cytokines that include interleukin-1 (IL-1). We report here that the levels of several matrix metalloproteinases (MMPs) are also elevated following a corticectomy trauma injury to the mouse CNS. The delayed upregulation of MMPs compared to that for IL-1 suggests the possibility that inflammatory cytokines regulate MMP production in CNS trauma. To resolve this, we developed a method to isolate and maintain highly enriched human fetal neurons or astrocytes in culture and examined the regulation by cytokines of the activity of a subgroup of MMPs, the gelatinases (MMP-2 and -9). While both neuronal and astrocytic cultures displayed comparable MMP-2 activity, as evidenced by gelatin zymography, levels of MMP-9 were proportionately higher in neurons compared to astrocytes. Of a variety of cytokines and growth factors tested in vitro, only IL-1beta was effective in increasing the neuronal expression of MMP-9. Finally, an IL-1 receptor antagonist attenuated the increase of neuronal MMP-9 in culture and abolished the injury-induced increase of MMP-9 in the mouse brain. These results implicate IL-1beta as a key regulator of neuronal MMP-9 in culture and of the elevation of MMP-9 that occurs following mouse CNS trauma.

Marked Inhibition of Tumor Growth in a Malignant Glioma Tumor Model by a Novel Synthetic Matrix Metalloproteinase

Abstract: Synthetic matrix metalloproteinase (MMP) inhibitors have activity against a variety of tumors in preclinical models but have not been studied in gliomas. We determined the effect of AG3340, a novel synthetic MMP inhibitor with K i values against gelatinases in the low picomolar range, on the growth of a human malignant glioma cell line (U87) in SCID-NOD mice. Mice were injected s.c. with U87 cells. Tumors were allowed to grow to a size of approximately 0.5 3 0.5 cm (after about 3 weeks), and the mice were randomized to receive either: (a) 100 mg/kg AG3340 in vehicle; or (b) vehicle control (0.5% carboxymethyl cellulose, 0.1% pluronic F68), both given daily i.p. Tumor area was measured twice weekly, and animals were sacrificed when moribund, or earlier if premorbid histology was examined. In vivo inhibition of tumor growth was profound, with AG3340 decreasing tumor size by 78% compared with controls after 31 days (when controls were sacrificed; P 2-fold increase in survival associated with tumor growth delay. Histological examination found that AG3340-treated tumors were smaller, had lower rates of proliferation, and significantly less invasion than controltreated tumors. Hepatic or pulmonary metastases were not seen in either group. In a separate experiment, the tumors were smaller and sampled after a shorter duration of treatment; the changes in proliferation were more marked and occurred earlier than differences in tumor invasion between the two groups. Furthermore, in vitro cell growth was not inhibited at AG3340 concentrations of < 1m M. AG3340 plasma concentrations in vivo, 1 h after administration, ranged from 67 to 365 nM. Thus, AG3340 produced a profound inhibition of glioma tumor growth and invasion. AG3340 markedly increased survival in this in vivo glioma model. Treatment with AG3340 may be potentially useful in patients with malignant gliomas.

Involvement of p21(Waf1/Cip1) in protein kinase C alpha-induced cell cycle progression.

Abstract: Protein kinase C (PKC) plays an important role in the regulation of glioma growth; however, the identity of the specific isoform and mechanism by which PKC fulfills this function remain unknown. In this study, we demonstrate that PKC activation in glioma cells increased their progression through the cell cycle. Of the six PKC isoforms that were present in glioma cells, PKC α was both necessary and sufficient to promote cell cycle progression when stimulated with phorbol 12-myristate 13-acetate. Also, decreased PKC α expression resulted in a marked decrease in cell proliferation. The only cell cycle-regulatory molecule whose expression was rapidly altered and increased by PKC α activity was the cyclin-cyclin-dependent kinase (CDK) inhibitor p21Waf1/Cip1. Coimmunoprecipitation studies revealed that p21Waf1/Cip1 upregulation was accompanied by an incorporation of p21Waf1/Cip1 into various cyclin-CDK complexes and that the kinase activity of these complexes was increased, thus resulting in cell cycle progression. Furthermore, depletion of p21Waf1/Cip1 by antisense strategy attenuated the PKC-induced cell cycle progression. These results suggest that PKC α activity controls glioma cell cycle progression through the upregulation of p21Waf1/Cip1, which facilitates active cyclin-CDK complex formation.