Limited efficacy of COX-2 inhibitors on nerve growth factor and metalloproteinases expressions in human synovial fibroblasts.

BACKGROUND: Nerve growth factor (NGF) is associated with arthritic pain and metalloproteinases are implicated in collagen and aggrecan degradation. Although selective COX-2 inhibitors are recommended for the treatment of arthritic diseases, their effects on NGF and metalloproteinases remain unclear. This study investigated the regulations of NGF and metalloproteinases by selective COX-2 inhibitors in isolated human synovial cells. METHODS: The isolated human synovial cells were stimulated with IL-1ß in the presence of selective COX-2 inhibitors (NS-398 or celecoxib) with or without exogenous PGE2 or its receptor (EP1-4) agonists. The expressions of NGF, MMP-1, -3, -13, ADAMTS-4, and -5 were quantified by real-time PCR and their proteins were determined by Western blotting. The amount of PGE2 released was measured by enzyme-linked immunosorbent assay (ELISA). RESULTS: The IL-1ß inductions of NGF and MMP-1 and MMP-13 were augmented by the COX-2 inhibitors, whereas the inductions of ADAMTS-4 and ADAMTS-5 were inhibited. These actions were reversed by supplementing PGE2 or the EP4 agonist exogenously. CONCLUSION: Our comprehensive analysis revealed that COX-2 inhibitors may be beneficial for suppressing aggrecan degradation and for reducing inflammatory pain by inhibiting PGE2 release, although they may have limited efficacy in suppressing collagen degradation and nerve growth. This study suggests the feedback roles of PGE2 in the negative regulation of NGF and MMP-1 and MMP-13 and the positive regulation of ADAMTS-4 and ADAMTS-5.

PGE1 Attenuates IL-1ß-induced NGF Expression in Human Intervertebral Disc Cells.

STUDY DESIGN: In vitro study using isolated human intervertebral disc (IVD) cells. OBJECTIVE: To investigate the effects of prostaglandin (PG)E1 and its orally available derivative limaprost on the regulation of nerve growth factor (NGF) expression and to compare their actions with other prostanoids using interleukin (IL)-1-stimulated human IVD cells. SUMMARY OF BACKGROUND DATA: We previously reported that a selective COX-2 inhibitor enhanced, whereas PGE2 suppressed the induction of NGF by IL-1 in human IVD cells, and proposed that PGE2 can suppress NGF expression by a negative feedback mechanism. METHODS: Isolated human IVD cells were stimulated with IL-1 in the presence or absence of increasing concentrations of PGE2, PGE1, limaprost, PGI2, PGD2, or PGF2α (10-10,000 nM). For some experiments, an E-series prostanoid receptor (EP)4 antagonist (L-161,982) was added prior to the stimulation. NGF expression was determined by real-time polymerase chain reaction and its protein level was quantified by enzyme-linked immunosorbent assay. RESULTS: PGE2, PGE1, and limaprost inhibited the IL-1-mediated induction of NGF in a concentration-dependent manner, with IC50 values of 9.9, 10.6, and 70.9 nM, respectively. PGI2 also suppressed NGF expression but to a much less extent. PGD2, on the other hand, significantly enhanced NGF expression, whereas PGF2α had no effect. Protein expression levels of NGF mirrored its mRNA levels. The suppression of NGF expression by PGE2 and PGE1 was partly reversed by L-161,982. CONCLUSION: PGE1 and limaprost exhibited a novel pharmacological action that suppresses NGF expression in human IVD cells, and other prostanoids differentially regulated NGF expression. Limaprost has been used to treat patients with lumbar spinal stenosis in Japan and was proved to be effective in relieving symptoms. Our in vitro results may explain, in part, the mechanism of action of limaprost for low back pain. LEVEL OF EVIDENCE: N/A.

Regulation of nerve growth factor by anti-inflammatory drugs, a steroid, and a selective cyclooxygenase 2 inhibitor in human intervertebral disc cells stimulated with interleukin-1.

STUDY DESIGN: Regulation of nerve growth factor (NGF) by 2 different anti-inflammatory drugs was investigated in vitro using isolated human intervertebral disc (IVD) cells stimulated with the proinflammatory cytokine interleukin-1 (IL-1). OBJECTIVE: To investigate the regulation of NGF by a synthetic steroid and a selective cyclooxygenase-2 (COX-2) inhibitor and to clarify the biological role of prostaglandin E2 (PGE2) in this process. SUMMARY OF BACKGROUND DATA: NGF is known to play an important role in pain, including low back pain, and to be induced by proinflammatory cytokines in IVD cells. However, the effect of clinically used drugs for managing low back pain on the regulation of NGF is unclear. METHODS: Isolated human IVD cells were stimulated with interleukin-1 (IL-1) in the presence or absence of dexamethasone or a selective COX-2 inhibitor (NS-398). NGF expression and release were determined by real-time polymerase chain reaction and enzyme-linked immuno sorbent assay, respectively. Inhibition of PGE2 release was determined by enzyme-linked immuno sorbent assay. The effects of exogenous PGE2 and its receptor (E-series prostanoid receptors [EPs] 1-4) agonists were also tested for NGF regulation. RESULTS: IL-1 transiently induced, in a dose-dependent manner, the induction of NGF in human IVD cells. Pretreatment with dexamethasone strongly inhibited the NGF expression, whereas NS-398 significantly enhanced it at the concentration at which PGE2 release was substantially inhibited. Exogenous PGE2 inhibited IL-1 induction of NGF and this effect was mimicked when EP2 and EP4, but not EP1 and EP3, agonists were supplemented to the culture. CONCLUSION: Although selective COX-2 inhibitors have been shown to be effective for acute low back pain by inhibiting PGE2 release, our findings suggest that it may have a limited efficacy because it exaggerated NGF expression, whereas dexamethasone inhibited it. On the other hand, PGE2 had an inhibitory function for NGF induction by mediating EP2/4 in human IVD cells. Further studies are needed to clarify whether these observations could take place in vivo. LEVEL OF EVIDENCE: N/A.

TLS-CHOP represses miR-486 expression, inducing upregulation of a metastasis regulator PAI-1 in human myxoid liposarcoma.

Myxoid liposarcomas (MLSs) are characterized by t(12;16)(q13;p11) translocation and expression of TLS-CHOP chimeric oncoprotein. However, the molecular functions of TLS-CHOP have not been fully understood. On the other hand, microRNAs (miRNAs) comprise an abundant class of endogenous small non-coding RNAs that negatively regulate the expression of their target genes, and are involved in many biological processes. It is now evident that dysregulation of miRNAs is an important step in the development of many cancers. To our knowledge, however, there have been no reports of the miRNAs involved in MLS tumorigenesis and development. In this study, we have found that miR-486 expression was repressed in TLS-CHOP-expressed NIH3T3 fibroblasts and MLS tissues, and exogenous overexpression of miR-486 repressed growth of MLS cells. Thus, downregulation of miR-486 may be an important process for MLS. In addition, we have identified plasminogen activator inhibitor-1 (PAI-1) as a novel target gene of miR-486. PAI-1 is a unique type of serine protease inhibitor and is known to be one of the key regulators of tumor invasion and metastasis. Furthermore, knockdown of PAI-1 by a specific small interfering RNA (siRNA) inhibited growth of MLS cells, suggesting that increased expression of PAI-1 by miR-486 repression is critical for survival of MLS cells. Collectively, these results suggest a novel essential molecular mechanism that TLS-CHOP activates PAI-1 expression by repression of miR-486 expression in MLS tumorigenesis and development.

[Updates on ossification of posterior longitudinal ligament. Effect of insulin/IGF-1 signals and leptin signals on ossification of the spinal ligament in Zucker fatty rats].

The involvement of insulin/IGF-1 signals and leptin signals in spinal ligament cells was investigated using Zucker fatty rats (fa/fa) that carry mutation of the leptin receptor gene (fa) and monosodium glutamate-treated (MSG) rats that present obesity due to destruction of the hypothalamic ventromedial nucleus. Zucker fatty rats (ZFR) , that have a with functional abnormality of leptin receptors are a spontaneous model of ossification of the posterior longitudinal ligament that develops sympathetic nerve hypoactivity. (insulin/IGF-1 signals) IRS-1-positive cells, IRS-1 protein were eminent by detected in the cartilage endplate and the enthesis region in ZFR group. On the other hand, IRS-2-positive cells were slightly less in the ZFR group than in the MSG and control groups. The results suggest that IRS-1-mediated signaling for cell proliferation was enhanced in ZFR, which may explain the ossification of the posterior longitudinal ligament. (Leptin signals) We investigated the effects of leptin on the spinal ligament in ZFR histopathologically and immunohistochemically. Since Ob-R does not play any role due to functional abnormality in ZFR, the direct involvement of leptin in ligament ossification may be slight in ZFR. beta(2)AR expression in the stage preceding ligament ossification was confirmed, suggesting that ossification of the spinal ligament may be inhibited by sympathetic nerve stimulation in ZFR.

Rhabdoid transformation of recurrent meningioma in the cervical cord: a case report.

We report a case of persistent local recurrence of rhabdoid meningioma in the cervical spinal cord. Recently, the meningioma has been reported to be undergoing rhabdoid transformation, but the clinical course is still unclear. Histopathological examination of the tumor showed that it was composed of both meningothelial cells and rhabdoid cells. At each recurrence of the tumor, the population of the rhabdoid cells had increased and the ability to grow had also increased, confirmed by the MIB-1 labeling index. This case showed that phenotypic change of the cells with "rhabdoid" morphology may affect meningiomas and that such changes are associated with aggressive biological and clinical behavior. This newly classified tumor should be recognized in the differential diagnosis of meningioma.