Wnt-7a Causes Loss of Differentiated Phenotype and Inhibits Apoptosis of Articular Chondrocytes via Different Mechanisms

Although regulation of chondrogenesis and cartilage development by Wnt signaling is well established, the function of Wnt in the maintenance and destruction of cartilage remains largely unknown. Here we investigated the involvement and regulatory mechanisms of Wnt signaling in cartilage destruction. We found that interleukin-1beta, the primary pro-inflammatory cytokine involved in cartilage destruction, induces expression of Wnt-5a and -7a in primary culture articular chondrocytes. The level of beta-catenin was also increased in chondrocytes of arthritic cartilage, suggesting the association of Wnt/beta-catenin signaling with arthritic cartilage destruction. In addition, our results show that Wnt-7a induces dedifferentiation and inhibits NO-induced apoptosis of primary culture articular chondrocytes. Wnt-7a induces dedifferentiation of articular chondrocytes by stimulating transcriptional activity of beta-catenin, whereas NO-induced apoptosis is inhibited via the activation of cell survival signaling, such as phosphatidylinositol 3-kinase and Akt, which block apoptotic signaling cascade. Our results collectively suggest that Wnt-7a is associated with cartilage destruction by regulating the maintenance of differentiation status and the apoptosis of articular chondrocytes via different mechanisms.

Actin cytoskeletal architecture regulates nitric oxide-induced apoptosis, dedifferentiation, and cyclooxygenase-2 expression in articular chondrocytes via mitogen-activated protein kinase and protein kinase C pathways

Nitric oxide (NO) in articular chondrocytes regulates differentiation, survival, and inflammatory responses by modulating ERK-1 and -2, p38 kinase, and protein kinase C (PKC) alpha and zeta. In this study, we investigated the effects of the actin cytoskeletal architecture on NO-induced dedifferentiation, apoptosis, cyclooxygenase (COX)-2 expression, and prostaglandin E2 production in articular chondrocytes, with a focus on ERK-1/-2, p38 kinase, and PKC signaling. Disruption of the actin cytoskeleton by cytochalasin D (CD) inhibited NO-induced apoptosis, dedifferentiation, COX-2 expression, and prostaglandin E2 production in chondrocytes cultured on plastic or during cartilage explants culture. CD treatment did not affect ERK-1/-2 activation but blocked the signaling events necessary for NO-induced dedifferentiation, apoptosis, and COX-2 expression such as activation of p38 kinase and inhibition of PKCalpha and -zeta. CD also suppressed activation of downstream signaling of p38 kinase and PKC, such as NF-kappaB activation, p53 accumulation, and caspase-3 activation, which are necessary for NO-induced apoptosis. NO production in articular chondrocytes caused down-regulation of phosphatidylinositol (PI) 3-kinase and Akt activities. The down-regulation of PI 3-kinase and Akt was blocked by CD treatment, and the CD effects on apoptosis, p38 kinase, and PKCalpha and -zeta were abolished by the inhibition of PI 3-kinase with LY294002. Our results collectively indicate that the actin cytoskeleton mediates NO-induced regulatory effects in chondrocytes by modulating down-regulation of PI 3-kinase and Akt, activation of p38 kinase, and inhibition of PKCalpha and -zeta

Non-steroidal anti-inflammatory drugs inhibit nitric oxide-induced apoptosis and dedifferentiation of articular chondrocytes independent of cyclooxygenase activity

Nitric oxide (NO) causes apoptosis and dedifferentiation of articular chondrocytes by the modulation of extracellular signal-regulated kinase (ERK), p38 kinase, and protein kinase C (PKC) alpha and -zeta. In this study, we investigated the effects and mechanisms of non-steroidal anti-inflammatory drugs (NSAIDs), such as indomethacin, ketoprofen, ibuprofen, sulindac sulfide, and flurbiprofen, in NO-induced apoptosis and dedifferentiation of articular chondrocytes. We found that all of the examined NSAIDs inhibited apoptosis and dedifferentiation. NO production in chondrocytes caused activation of ERK-1/2 and p38 kinase, which oppositely regulate apoptosis and dedifferentiation. NO production also caused inhibition of PKCalpha and -zeta independent of and dependent on, respectively, p38 kinase, which is required for apoptosis and dedifferentiation. Among the signaling molecules modulated by NO, NSAIDs blocked NO-induced activation of p38 kinase, potentiated ERK activation, and blocked inhibition of PKCalpha and -zeta. NSAIDs also inhibited some of the apoptotic signaling that is downstream of p38 kinase and PKC, such as NFkappaB activation, p53 accumulation, and caspase-3 activation. The inhibitory effects of NSAIDs on apoptosis and dedifferentiation were independent of the inhibition of cyclooxygenase (COX)-2 and prostaglandin E(2) (PGE(2)) production, as evidenced by the observation that specific inhibition of COX-2 activity and PGE(2) production or exogenous PGE(2) did not affect NO-induced apoptosis and dedifferentiation. Taken together, our results indicate that NSAIDs block NO-induced apoptosis and dedifferentiation of articular chondrocytes by the modulation of ERK, p38 kinase, and PKCalpha and -zeta in a manner independent of their ability to inhibit COX-2 and PGE(2) production.

Regulation of the chondrocyte phenotype by beta-catenin

beta-Catenin regulates important biological processes, including embryonic development and tumorigenesis. We have investigated the role of beta-catenin in the regulation of the chondrocyte phenotype. Expression of beta-catenin was high in prechondrogenic mesenchymal cells, but significantly decreased in differentiated chondrocytes both in vivo and in vitro. Accumulation of beta-catenin by the inhibition of glycogen synthase kinase-3beta with LiCl inhibited chondrogenesis by stabilizing cell-cell adhesion. Conversely, the low level of beta-catenin in differentiated articular chondrocytes was increased by post-translational stabilization during phenotypic loss caused by a serial monolayer culture or exposure to retinoic acid or interleukin-1beta. Ectopic expression of beta-catenin or inhibition of beta-catenin degradation with LiCl or proteasome inhibitor caused de-differentiation of chondrocytes. Transcriptional activation of beta-catenin by its nuclear translocation was sufficient to cause phenotypic loss of differentiated chondrocytes. Expression pattern of Jun, a known target gene of beta-catenin, is essentially the same as that of beta-catenin both in vivo and in vitro suggesting that Jun and possibly activator protein 1 is involved in the beta-catenin regulation of the chondrocyte phenotype.

Regulation of the chondrocyte phenotype by beta-catenin

beta-Catenin regulates important biological processes, including embryonic development and tumorigenesis. We have investigated the role of beta-catenin in the regulation of the chondrocyte phenotype. Expression of beta-catenin was high in prechondrogenic mesenchymal cells, but significantly decreased in differentiated chondrocytes both in vivo and in vitro. Accumulation of beta-catenin by the inhibition of glycogen synthase kinase-3beta with LiCl inhibited chondrogenesis by stabilizing cell-cell adhesion. Conversely, the low level of beta-catenin in differentiated articular chondrocytes was increased by post-translational stabilization during phenotypic loss caused by a serial monolayer culture or exposure to retinoic acid or interleukin-1beta. Ectopic expression of beta-catenin or inhibition of beta-catenin degradation with LiCl or proteasome inhibitor caused de-differentiation of chondrocytes. Transcriptional activation of beta-catenin by its nuclear translocation was sufficient to cause phenotypic loss of differentiated chondrocytes. Expression pattern of Jun, a known target gene of beta-catenin, is essentially the same as that of beta-catenin both in vivo and in vitro suggesting that Jun and possibly activator protein 1 is involved in the beta-catenin regulation of the chondrocyte phenotype.

p38 kinase regulates nitric oxide-induced apoptosis of articular chondrocytes by accumulating p53 via NFkappa B-dependent transcription and stabilization by serine 15 phosphorylation

Nitric oxide (NO) during primary culture of articular chondrocytes causes apoptosis via p38 mitogen-activated protein kinase in association with elevation of p53 protein level, caspase-3 activation, and differentiation status. In this study, we characterized the molecular mechanism by which p38 kinase induces apoptosis through activation of p53. We report here that NO-induced activation of p38 kinase leads to activation of NFkappaB, which in turn induces transcription of the p53 gene. Activated p38 kinase also physically associates and phosphorylates the serine 15 residue of p53, which results in accumulation of p53 protein during NO-induced apoptosis. Ectopic expression of wild-type p53 enhanced NO-induced apoptosis, whereas expression of a dominant negative p53 blocked it, indicating that p53 plays an essential role in NO-induced apoptosis of chondrocytes. The increased accumulation of p53 caused expression of Bax, a pro-apoptotic member of the Bcl-2 family that is known to cause apoptosis via release of cytochrome c and caspase activation. These results suggest that NO-activated p38 kinase activates p53 function in two different ways, transcriptional activation by NFkappaB and direct phosphorylation of p53 protein, leading to apoptosis of articular chondrocytes.

p38 kinase-dependent and -independent Inhibition of protein kinase C zeta and -alpha regulates nitric oxide-induced apoptosis and dedifferentiation of articular chondrocytes

In articular chondrocytes, nitric oxide (NO) production triggers dedifferentiation and apoptotic cell death that is regulated by the converse functions of two mitogen-activated protein kinase subtypes, extracellular signal-regulated kinase (ERK) and p38 kinase. Since protein kinase C (PKC) transduces signals that influence differentiation, survival, and apoptosis of various cell types, we investigated the roles and underlying molecular mechanisms of action of PKC isoforms in NO-induced dedifferentiation and apoptosis of articular chondrocytes. We report here that among the expressed isoforms, activities of PKCalpha and -zeta were reduced during NO-induced dedifferentiation and apoptosis. Inhibition of PKCalpha activity was independent of NO-induced activation of ERK or p38 kinase and occurred due to blockage of expression. On the other hand, PKCzeta activity was inhibited as a result of NO-induced p38 kinase activation and was observed prior to proteolytic cleavage by a caspase-mediated process to generate enzymatically inactive fragments. Inhibition of PKCalpha or -zeta activities potentiated NO-induced apoptosis, whereas ectopic expression of these isoforms significantly reduced the number of apoptotic cells and blocked dedifferentiation. Ectopic expression of PKCalpha or -zeta did not affect p38 kinase or ERK but inhibited the p53 accumulation and caspase-3 activation that are required for NO-induced apoptosis of chondrocytes. Therefore, our results collectively indicate that p38 kinase-independent and -dependent inhibition of PKCalpha and -zeta, respectively, regulates NO-induced apoptosis and dedifferentiation of articular chondrocytes.

Regulation of leukemic cell adhesion, proliferation, and survival by beta-catenin

In epithelial cells beta-catenin plays a critical role as a component of the cell-cell adhesion apparatus and as a coactivator of the TCF/LEF (T-cell transcription factor/lymphoid enhancer binding factor) family of transcription factors. Deregulation of beta-catenin has been implicated in the malignant transformation of cells of epithelial origin. However, a function for beta-catenin in hematologic malignancies has not been reported. beta-Catenin is not detectable in normal peripheral blood T cells but is expressed in T-acute lymphoblastic leukemia cells and other tumor lines of hematopoietic origin and in primary lymphoid and myeloid leukemia cells. beta-Catenin function was examined in Jurkat T-acute lymphoblastic leukemia cells. Overexpression of dominant-negative beta-catenin or dominant-negative TCF reduced beta-catenin nuclear signaling and inhibited Jurkat proliferation and clonogenicity. Similarly, these constructs inhibited proliferation of K562 and HUT-102 cells. Reduction of beta-catenin expression with beta-catenin antisense down-regulated adhesion of Jurkat cells in response to phytohemagglutinin. Incubation of Jurkat cells with anti-Fas induced caspase-dependent limited proteolysis of beta-catenin N- and C-terminal regions and rapid redistribution of beta-catenin to the detergent-insoluble cytoskeleton, concomitant with a marked decline in nuclear beta-catenin signaling. Fas-mediated apoptosis was potentiated by inhibition of beta-catenin nuclear signaling. The data suggest that beta-catenin can play a significant role in promoting leukemic cell proliferation, adhesion, and survival.

In vivo effects of Panax ginseng extracts on the cytochrome P450-dependent monooxygenase system in the liver of 2,3,7,8-tetrachlorodibenzo-p-dioxin-exposed guinea pig

The effects of the subchronic administration of Panax ginseng extracts were examined on the hepatic cytochrome P450-dependent monooxygenase system of guinea pigs pre-exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Panax ginseng extracts were intraperitoneally administered to guinea pigs at 100 mg/kg/day for 14 days from 1 week after a single intraperitoneal injection of 1 microg of TCDD/kg of body weight. TCDD treatment increased the total cytochrome P450 content 2.86-fold, and this was remarkably inhibited by the administration of Panax ginseng extracts. Treatment with ginseng extract alone also decreased the contents of cytochrome P450 by 33%, but both TCDD and ginseng extracts had no effect on cytochrome b(5) content. The administration of TCDD resulted in a 1.73-fold increase in microsomal NADPH-cytochrome P450 reductase activity in the guinea pig liver, and this was significantly inhibited by ginseng extracts, but treatment with ginseng extracts alone had no effect on its activity, and no statistical changes in the activity of NADPH-cytochrome b(5) reductase were observed in guinea pig liver due to TCDD and/or ginseng extract administration. Compared to the control, ECOD activity remarkably (1.76-fold) increased after TCDD administration, but this increase was completely inhibited by treatment with ginseng extract. Treatment with ginseng extract alone resulted in a 50% reduction of ECOD activity. TCDD administration remarkably induced benzphetamine demethylation (BPDM) activity, while ginseng extract also slightly increased the enzyme's activity, but the induction attributed to ginseng extracts was not statistically significant. Even though administration of ginseng extracts slightly inhibited TCDD-induced BPDM activity, the inhibition was not statistically significant. These results indicate that ginseng extract exerts different effect on the induction of P450 isozymes. From these results, we suggest that Panax ginseng extracts may act as an inhibitor of CYP1A rather than that of CYP2B.

Caspase-dependent deubiquitination of monoubiquitinated nucleosomal histone H2A induced by diverse apoptogenic stimuli

Enzymatic deubiquitination of mono-ubiquitinated nucleosomal histone H2A (uH2A) and H2B (uH2B) is closely associated with mitotic chromatin condensation, although the function of this histone modification in cell division remains ambiguous. Here we show that rapid and extensive deubiquitination of nucleosomal uH2A occurs in Jurkat cells undergoing apoptosis initiated by anti-Fas activating antibody, staurosporine, etoposide, doxorubicin and the proteasome inhibitor, N-acetyl-leucyl-leucyl-norlucinal. These diverse apoptosis inducers also promoted the accumulation of slowly migrating, high molecular weight ubiquitinated proteins and depleted the cellular pool of unconjugated ubiquitin. In apoptotic cells, ubiquitin was cleaved from uH2A subsequent to the appearance of plasma membrane blebbing, and deubiquitination of uH2A closely coincided with the onset of nuclear pyknosis and chromatin condensation. Nucleosomal uH2A deubiquitination, poly (ADP-ribose)polymerase (PARP) cleavage and chromatin condensation were prevented in cells challenged with apoptosis inducers by pretreatment with the pan-caspase inhibitor, zVAD-fmk, or by over-expressing anti-apoptotic Bcl-xL protein. These results implicate a connection between caspase cascade activation and nucleosomal uH2A deubiquitination. Transient transfection of 293 cells with the gene encoding Ubp-M, a human deubiquitinating enzyme, promoted uH2A deubiquitination, while an inactive mutated Ubp-M enzyme did not. However, Ubp-M-promoted deubiquitination of uH2A was insufficient to initiate apoptosis in these cells. We conclude that uH2A deubiquitination is a down-stream consequence of procaspase activation and that unscheduled cleavage of ubiquitin from uH2A is a consistent feature of the execution phase of apoptosis rather than a determining or initiating apoptogenic event. Nucleosomal uH2A deubiquitination may function as a cellular sensor of stress in situations like apoptosis through which cells attempt to preserve genomic integrity.

Molecular cloning of kpcA gene encoding a Kex2p-like endoprotease from Aspergillus nidulans

We cloned and sequenced a gene, kpcA (Kex2p-like proprotein convertase A), from a genomic library of Aspergillus nidulans. The kpcA gene encodes an 820-residue protein, named KpcA, which contains a putative subtilisin-like catalytic domain (residues 136-466) homologous to that of the subtilisin serine protease family. KpcA shows 56, 73, and 47% amino acid identities with Saccharomyces cerevisiae Kex2p, Aspergillus niger KexB, and mouse furin within the subtilisin-like catalytic domain, respectively. The sequences around the proposed active site Asp, His, and Ser residues of KpcA are similar to those of other Kex2p family members. The KpcA mRNA transcript with an expected size of approximately 2.8 kb was detected in A. nidulans. The substrate specificity of KpcA, expressed in CHO cells, is similar to that of A. niger KexB and yeast Kex2p. We conclude that KpcA is a resident Kex2p-like proprotein that processes endoprotease in A. nidulans.

Induction of apoptotic cell death by a p53-independent pathway in neuronal SK-N-MC cells after treatment with 2,2',5,5'-tetrachlorobiphenyl

Apoptotic cell death is an active process, which is a critical feature of the regulated development of multicellular organisms. Polychlorinated biphenyls (PCBs) are ubiquitous environmental contaminants, some of which may be neurotoxic. This study investigates the 2,2', 5,5'-tetrachlorobiphenyl (PCB 52) induced apoptosis in human neuronal SK-N-MC cells, and the role of p53 in this response. Upon treatments with PCB 52, time- and concentration-dependent inhibition of the cell viability was observed. PCB 52 also caused apoptosis, as measured by cell morphology and DNA fragmentation. The capability of PCB 52 to induce apoptosis was associated with the proteolytic cleavage of specific target proteins, such as poly(ADP-ribose) polymerase (PARP) and beta-catenin proteins, suggesting the possible involvement of caspases. In general, DNA-damaging agents induce accumulation of the tumor suppressor protein p53, leading cells to either growth arrest in G1, or apoptosis. However, our data showed that both p53 and Bcl-2 protein levels were decreased in a time-dependent manner during apoptosis after exposure to PCB 52. These results suggest that PCB 52 induced a p53-independent apoptosis in these cells.

Increased expression and localization of a serine protease inhibitor, protease nexin-1 (PN-1), in the ovary and uterus during implantation in rat

Protease nexin-1 (PN-1) is a serine protease inhibitor (serpin) that inactivates several proteases, including thrombin, urokinase, plasminogen activators (PA), and plasmin. It also plays a role in regulating proteolytic activity generated by PA system. PN-1 is known to be involved in tissue remodeling, cellular invasiveness, matrix degradation, and tumor growth. However, the role of PN-1 in female reproductive tracts, such as the uterus, ovary, and oviduct, during pregnancy is not known. The present study was designed to investigate the changes of PN-1 mRNA level and localization in the tracts during implantation and early pregnancy by using reverse transcription (RT)-polymerase chain reaction (PCR) and in situ hybridization. We found that PN-1 mRNA levels were coordinately regulated during early pregnancy in a stage- and tissue-specific manner, such that an increased expression of PN-1 gene appeared at the time of the implantation period in the uterus and ovary. Both the uterus and ovary synthesized PN-1 mRNA and their maximal PN-1 expression occurred on Day 6.5 postcoitum (p.c.). On 13.5 days of pregnancy, PN-1 level was low in the uterus and ovary. On the other hand, PN-1 mRNA in the oviduct did not show after 6.5 days of pregnancy. It appears that PN-1 mRNA in the uterus and ovary was highly regulated during early pregnancy, which might have an important role in implantation of rat blastocysts. PN-1 was localized in endometrial stromal cells of the uterus and in granulosa cells of the unstimulated primary follicles in the ovary during periimplantation period. Also, PN-1 mRNA expression was higher at implantation period than that at nonimplantation period of pregnancy. In conclusion, PN-1 is expressed in female reproductive tracts and highly regulated during implantation and early pregnancy.

Viral interferon regulatory factor 1 of Kaposi's sarcoma-associated herpesvirus binds to p53 and represses p53-dependent transcription and apoptosis

Kaposi's sarcoma-associated herpesvirus (KSHV) is related to the development of Kaposi's sarcoma. Open reading frame K9 of KSHV encodes viral interferon regulatory factor 1 (vIRF1), which functions as a repressor of interferon- and IRF1-mediated signal transduction. In addition, vIRF1 acts as an oncogene to induce cellular transformation. Here we show that vIRF1 directly associates with the tumor suppressor p53 and represses its functions. The vIRF1 interaction domains of p53 are the DNA binding domain (amino acids [aa] 100 to 300) and the tetramerization domain (aa 300 to 393). p53 interacts with the central region (aa 152 to 360) of vIRF1. vIRF1 suppresses p53-dependent transcription and deregulates its apoptotic activity. These results suggest that vIRF1 may regulate cellular function by inhibiting p53.

Prevention of cisplatin-DNA adduct repair and potentiation of cisplatin-induced apoptosis in ovarian carcinoma cells by proteasome inhibitors

Histones H2A and H2B are known to be reversibly post-translationally modified by ubiquitination. We previously observed in cultured tumor cells that proteasome inhibition stabilizes polyubiquitinated proteins, depletes unconjugated ubiquitin, and thereby promotes the deubiquitination of nucleosomal histones in chromatin. Provocative indirect evidence suggests that histone ubiquitination/deubiquitination cycles alter chromatin structure, which may limit accessibility of DNA repair proteins to damaged sites. In the present study, we focused on the relationship between the ubiquitination status of histone H2A, the structure of chromatin, and the efficiency of nucleotide excision repair (NER) of cisplatin-DNA adducts in human ovarian carcinoma cells exposed to the antitumor drug cisplatin. Pretreating cells with the proteasome inhibitor lactacystin (LC) or N-acetyl-leucyl-leucyl-norleucinal (ALLnL) induced deubiquitination of ubiquitinated histone H2A (uH2A) and concomitantly promoted chromatin condensation, increased the extent of cisplatin-DNA adducts, and diminished NER-dependent repair of cisplatin-DNA lesions, compared with control cells treated with cisplatin alone. Both proteasome inhibitors also prevented the increase in ERCC-1 mRNA expression that occurs in cells exposed to cisplatin. Cells treated with the combination of ALLnL and cisplatin underwent apoptosis, as indicated by caspase-dependent poly(ADP-ribose) polymerase (PARP) cleavage, more quickly than cells treated with either agent alone. Additionally, the combination of ALLnL and cisplatin potently increased p53 levels in cell lysates and stimulated the binding of p53 to chromatin. Together, these observations suggest that proteasome inhibition may be exploited therapeutically for its potential to sensitize ovarian tumor cells to cisplatin.

Induction of apoptosis in p16INK4A mutant cell lines by adenovirus-mediated overexpression of p16INK4A protein

The tumor suppressor gene p16INK4A is a cyclin-dependent kinase inhibitor (CDKI) and an important cell cycle regulator. We have previously constructed a recombinant adenovirus which expresses p16 (Adp16) and shown that infection in a variety of human tumor cell lines with this recombinant virus results in high levels of p16INK4A protein expression resulting in cell cycle arrest and loss of cyclin-cdk activity. Furthermore, adenoviral-mediated overexpression of wild-type p16INK4A is more toxic in cancer cells which express mutant forms of p16INK4A compared to cancer cell lines containing endogenous wild-type p16. TUNEL assay and DAPI staining following infection of MDA-MB 231 breast cancer cells with Adp16 indicate that p16INK4A-mediated cytotoxicity was associated with apoptosis. This is supported by studies demonstrating a decrease in cpp32 and cyclinB1 protein levels and induction of poly (ADP-ribose) polymerase (PARP) cleavage following infection of MDA-MB-231 cells with Adp16. These results suggest that gene therapy using Adp16 may be a promising treatment option for human cancers containing alterations in p16 expression.

Chlorophyllin suppression of lipopolysaccharide-induced nitric oxide production in RAW 264.7 cells

Chlorophyllin (CHL), a water-soluble derivative of chlorophyll, functions as an anticarcinogen and antioxidant. In the present study, we investigated the effect of CHL on nitric oxide production in lipopolysaccharide (LPS)-stimulated RAW 264.7 cells. Treatment with CHL inhibited nitric oxide production in the LPS-stimulated RAW 264. 7 cells in a dose-related manner. Competitive RT-PCR analysis, using a DNA competitor as an internal standard, demonstrated that the treatment with 1, 10, and 50 microM CHL decreased LPS-induced iNOS mRNA expression in a concentration-dependent manner. Since the expression of the iNOS gene is mainly regulated by NF-kappaB, we then examined the effects of CHL on the NF-kappaB DNA binding activity, using an electrophoretic mobility shift assay. CHL down-regulated the NF-kappaB DNA binding on its cognate recognition site at the concentrations just noted. Employing a transfection and reporter gene expression system with p(NF-kappaB)(3)-chloramphenicol acetyl transferase (CAT), the treatment of CHL produced a dose-dependent inhibition of CAT activity in RAW 264.7 cells. Furthermore, CHL partially restored LPS-decreased IkappaBalpha, an inhibitory protein against NF-kappaB activation, in the cytosolic extract from the LPS-treated cells determined by immunoblot analysis. CHL also protected the hydroxyl radical-induced cytotoxicity in RAW 264.7 cells, indicating its antioxidant effect. These results suggest that CHL suppresses the nitric oxide production and iNOS mRNA expression mediated by the inhibition of NF-kappaB activation, and its action mechanism may be based on its antioxidant effect.

Protease inhibitor-induced apoptosis: accumulation of wt p53, p21WAF1/CIP1, and induction of apoptosis are independent markers of proteasome inhibition

Inhibitors of proteases are currently emerging as a potential anti-cancer modality. Nonselective protease inhibitors are cytotoxic to leukemia and cancer cell lines and we found that this cytotoxicity is correlated with their potency as inhibitors of the proteasome but not as inhibitors of calpain and cathepsin. Highly selective inhibitors of the proteasome were more cytotoxic and fast-acting than less selective inhibitors (PS341>>ALLN>>ALLM). Induction of wt p53 correlated with inhibition of the proteasome and antiproliferative effect in MCF7, a breast cancer cell line, which was resistant to apoptosis caused by proteasome inhibitors. In contrast, inhibitors of the proteasome induced apoptosis in four leukemia cell lines lacking wt p53. The order of sensitivity of leukemia cells was: Jurkat>HL60> or =U937>>K562. The highly selective proteasome inhibitor PS-341 induced cell death with an IC50 as low as 5 nM in apoptosis-prone leukemia cells. Cell death was preceded by p21WAF1/CIP1 accumulation, an alternative marker of proteasome inhibition, and by cleavage of PARP and Rb proteins and nuclear fragmentation. Inhibition of caspases abrogated PARP cleavage and nuclear fragmentation and delayed, but did not completely prevent cell death caused by PS-341. Reintroduction of wt p53 into p53-null PC3 prostate carcinoma cells did not increase their sensitivity to proteasome inhibitors. Likewise, comparison of parental and p21-deficient cells demonstrated that p21WAF1/CIP1 was dispensable for proteasome inhibitor-induced cytotoxicity. We conclude that accumulation of wt p53 and induction of apoptosis are independent markers of proteasome inhibition.

Organo-axial volvulus of the stomach with diaphragmatic eventration

Gastric volvulus occurs when the stomach rotates about its longitudinal axis (organo-axial volvulus), or about an axis joining the lesser and greater curvatures (mesentero-axial volvulus). Primary gastric volvulus, making up one third of cases, occurs when the stabilizing ligaments are too lax as a result of congenital or acquired causes. Secondary gastric volvulus, making up the remainder of cases, occurs in association with a paraesophageal hernia or other congenital or acquired diaphragmatic defects. While gastric volvulus may occur acutely, especially in children, it may not be clinically apparent and discovered incidentally. The authors present a case of chronic organo-axial volvulus of the stomach secondary to left hemidiaphragmatic eventration with a review of the relevant literature.

Cutaneous Rosai-Dorfman disease--a pathologic review of 2 cases

Rosai-Dorfman disease, also known as sinus histiocytosis with massive lymphadenopathy, is a rare but distinct clinicopathologic entity characterised histologically by a benign s histiocytic proliferation. Isolated involvement of extranodal sites without concomitant nodal disease is rare. We describe the pathological features of 2 cases of Rosai-Dorfman disease that were clinically confined to the skin. In both male adult Chinese patients, proliferation of histiocytes was accompanied by S-100 protein expression demonstrated immunohistochemically within the histiocytes. The pathology of Rosai-Dorfman disease and its microscopic differential diagnoses are discussed.

Nuclear beta-catenin displays GSK-3beta- and APC-independent proteasome sensitivity in melanoma cells

Colon carcinoma and melanoma cells containing either a deletion of the adenomatous polyposis coli tumor suppressor protein (APC) or mutation of the site in beta-catenin phosphorylated by glycogen synthase kinase-3beta (GSK-3beta) display elevated levels of detergent-soluble beta-catenin due to insensitivity of the cytosolic protein to proteasome-dependent degradation. In this study, we have examined the effect of beta-catenin mutation (S37F) or APC loss on the proteasome sensitivity of additional subcellular beta-catenin pools in melanoma cells. In contrast to detergent-soluble beta-catenin, the detergent-insoluble protein remains proteasome-sensitive irrespective of S37F mutation or APC status. This insoluble component appears associated primarily with nuclear cytoskeletal elements. In addition, DNase I treatment solubilized a portion of detergent-insoluble beta-catenin, suggesting that this fraction also contains chromatin-associated protein, and correlating with a proteasome-sensitive elevation in beta-catenin-stimulated reporter activity. Since the detergent-insoluble nuclear component of beta-catenin displays GSK-3beta- and APC-independent proteasome sensitivity, distinct from the soluble nuclear and cytosolic pools of this protein, regulation of beta-catenin proteasome sensitivity and the contribution of this process to beta-catenin function may be more complex than previously appreciated.

Diversity of core promoter mutations in immune clearance phase of chronic HBV infection

BACKGROUND/AIMS

Transcription of HBV (hepatitis B virus) pre-core and pre-genomic mRNAs is controlled by core promoter. Therefore, mutations in the core promoter region might change the activity of liver diseases through an altered transcriptional level of the mRNA. The present study was carried out to determine the diversity of HBV core promoter sequences in chronic HBV carriers.

METHODS

DNA sequences in the core promoter region were determined after cloning the PCR product. Two groups of chronic HBV carriers with HBeAg, including five cases of asymptomatic carriers (ASCs, 21 clones) and eight with chronic hepatitis (CH, 50 clones) were studied.

RESULTS

Mutations in the core promoter were found in three out of the ASCs (11 clones), and in all eight cases in the CH group (48 clones). While mutations at nucleotide 1762 (A-->T) and 1764(G-->A) were not found in ASC, mutations at the same positions were found in all the cases of CH group (40 clones) (P=0.003). Diverse patterns of mutations in the core promoter were observed in each patient in the CH group.

CONCLUSIONS

Further studies are needed to determine whether the diversity of HBV core promoter mutations has clinical significance such as the seroconversion of HBeAg to anti-HBe.

Posttranslational regulation of the retinoblastoma gene family member p107 by calpain protease

The retinoblastoma protein plays a critical role in regulating the G1/S transition. Less is known about the function and regulation of the homologous pocket protein p107. Here we present evidence for the posttranslational regulation of p107 by the Ca2+-activated protease calpain. Three negative growth regulators, the HMG-CoA reductase inhibitor lovastatin, the antimetabolite 5-fluorouracil, and the cyclic nucleotide dibutyryl cAMP were found to induce cell type-specific loss of p107 protein which was reversible by the calpain inhibitor leucyl-leucyl-norleucinal but not by the serine protease inhibitor phenylmethylsulfonylfluoride, caspase inhibitors, or lactacystin, a specific inhibitor of the 26S proteasome. Purified calpain induced Ca2+-dependent p107 degradation in cell lysates. Transient expression of the specific calpain inhibitor calpastatin blocked the loss of p107 protein in lovastatin-treated cells, and the half-life of p107 was markedly lengthened in lovastatian-treated cells stably transfected with a calpastatin expression vector versus cells transfected with vector alone. The data presented here demonstrate down-regulation of p107 protein in response to various antiproliferative signals, and implicate calpain in p107 posttranslational regulation.

Recombinant adenovirus expressing Von Hippel-Lindau-mediated cell cycle arrest is associated with the induction of cyclin-dependent kinase inhibitor p27Kip1

A recombinant adenovirus containing the Von Hippel-Lindau (VHL) cDNA was constructed (AdVHL) and used to investigate the function of this tumor suppressor gene. Exposure of renal and breast cancer cell lines to AdVHL resulted in high levels of VHL mRNA and protein. AdVHL infection resulted in G1 cell cycle arrest and growth inhibition of renal and breast cancer cell lines. AdVHL-mediated cell cycle arrest was associated with induction of the cyclin-dependent kinase inhibitor (CDKI) p27Kip1 and inhibition of CDK2 and cyclinB1-dependent cdc2 activities. Nuclear run-on analyses and actinomycin D inhibition studies indicate that the induction of p27Kip1 RNA by VHL is mediated at least in part through an increase in p27Kip1 mRNA synthesis. Furthermore, [35S]methionine pulse-chase studies indicate that the increase in p27Kip expression is also regulated through posttranscriptional control mechanisms. These studies support a novel concept that the tumor suppressor gene VHL controls cell cycle progression by regulation of p27Kip1 at both the mRNA and protein levels.

Colonoscopic diagnosis of whipworm infection

Trichuriasis is an intestinal infection found in human beings which is caused by Trichuris trichiura, more commonly known as whipworm because of its whip-like appearance. It is characterized by the invasion of the colonic mucosa by the adult Trichuris and produces minor inflammatory changes at the sites of localization. It is prevalent throughout the world, especially in tropical areas. Its diagnosis is usually made by identification of the typical eggs in the stool; adult whipworm is rarely seen during colonoscopy. Colonoscopy can directly diagnose trichuriasis, confirming the threadlike form of worms with an attenuated end. The worms can be overlooked, particularly if colon preparation is imperfect. Attenuated whip-like ends of whipworms, which are embedded in the colonic mucosa, were removed with biopsy forceps. We report on 5 cases of whipworm infection that were diagnosed on total colonoscopy.

Preliminary results of a new covered biliary metal stent for malignant biliary obstruction

BACKGROUND AND STUDY AIMS

The biliary stents in current use have a tendency to be blocked, so we designed a self-expandable metal stent covered with polyurethane to overcome the risk of tumor ingrowth of uncovered self-expandable metal stents. To evaluate the success and the effectiveness of the new membrane-covered self-expandable metal stent (covered modified Gianturco biliary stent), we studied patients with biliary obstruction caused by biliopancreatic carcinoma.

PATIENTS AND METHODS

We retrospectively evaluated 47 patients with malignant biliary obstruction to receive either a newly developed self-expandable metal stent covered with polyurethane (21 cases) or an uncovered metal stent (Strecker stent or Wallstent, 26 cases) by the endoscopic transpapillary route.

RESULTS

The success rate of stent insertion and drainage effect of stent showed no statistical difference in patients with a new membrane-covered self-expandable metal stent compared with those with an uncovered metal stent (90.4% vs. 88.5%, P > 0.05; and 100% vs. 95.6%, P > 0.05, respectively). The median patency of the stent was slightly prolonged in patients with a membrane-covered self-expandable metal stent, but there was no statistical difference between two groups (267 vs. 233 days, P > 0.05). The rate of early complication related to stent insertion showed no significant difference between the two groups. During the follow-up period, stent occlusion due to tumor ingrowth occurred in two patients (10.5%) in the membrane-covered, self-expandable stent group, compared with six patients (26.1%) in the uncovered metal stent group. The membrane-covered metal stent was removed successfully and a polyethylene stent was reinserted in one patient who had developed tumor overgrowth.

CONCLUSIONS

A new, membrane-covered, self-expandable metal stent has a tendency towards better long-term patency than the uncovered metal stent, and it can effectively prevent tumor ingrowth into the stent. Also it is possible to remove an occluded membrane-covered stent. However, a case-controlled study, including a larger patient number, and long-term follow-up are needed.

Suppression of interleukin-2 by the putative endogenous cannabinoid 2-arachidonyl-glycerol is mediated through down-regulation of the nuclear factor of activated T cells

2-Arachidonyl-glycerol (2-Ara-Gl) recently was identified as a putative endogenous ligand for cannabinoid receptor types CB1 and CB2 by competitive binding. More recent immune function assays demonstrated that 2-Ara-Gl possessed immunomodulatory activity. Because several plant-derived cannabinoids inhibit interleukin-2 (IL-2) expression, 2-Ara-Gl was investigated for its ability to modulate this cytokine. The direct addition of 2-Ara-Gl to mouse splenocyte cultures suppressed phorbol-12-myristate-13-acetate plus ionomycin-induced IL-2 secretion and steady state mRNA expression in a dose-dependent manner. 2-Ara-Gl also produced a marked inhibition of IL-2 promotor activity as determined by transient transfection of EL4.IL-2 cells with a pIL-2-CAT construct. 2-Ara-Gl at 5, 10, 20, and 50 microM suppressed phorbol-12-myristate-13-acetate plus ionomycin-induced IL-2 promotor activity by 18%, 28%, 39%, and 54%, respectively. To further characterize the mechanism for the transcriptional regulation of IL-2 by 2-Ara-Gl, the DNA-binding activity of transcription factors, nuclear factor of activated T cells (NF-AT), nuclear factor for immunoglobulin kappa chain in B cells (NF-kappa B/Rel), activator protein-1(AP-1), octamer, and cAMP-response element binding protein was evaluated by electrophoretic mobility shift assay in mouse splenocytes. In addition, a reporter gene expression system for p(NF-kappa B)3-CAT, p(NF-AT)3-CAT, and p(AP-1)3-CAT was used in transiently transfected EL4.IL-2 cells to determine the effect of 2-Ara-Gl on promoter activity for each of the specific transcription factors. 2-Ara-Gl reduced both the NF-AT-binding and promoter activity in a dose-dependent manner and, to a lesser degree, NF-kappa B/Rel-binding and promoter activity. No significant effect was observed on octamer- and cAMP-response element-binding activity. AP-1 DNA-binding activity was not inhibited by 2-Ara-Gl, but a modest inhibition of promoter activity was observed.

Differentiation of pancreatic epithelial progenitor cells into hepatocytes following transplantation into rat liver

The ability to identify, isolate, and transplant progenitor cells from solid tissues would greatly facilitate the treatment of diseases currently requiring whole organ transplantation. In this study, cell fractions enriched in candidate epithelial progenitor cells from the rat pancreas were isolated and transplanted into the liver of an inbred strain of Fischer rats. Using a dipeptidyl dipeptidase IV genetic marker system to follow the fate of transplanted cells in conjunction with albumin gene expression, we provide conclusive evidence that, after transplantation to the liver, epithelial progenitor cells from the pancreas differentiate into hepatocytes, express liver-specific proteins, and become fully integrated into the liver parenchymal structure. These studies demonstrate the presence of multipotent progenitor cells in the adult pancreas and establish a role for the liver microenvironment in the terminal differentiation of epithelial cells of foregut origin. They further suggest that such progenitor cells might be useful in studies of organ repopulation following acute or chronic liver injury.

In situ detection of hepatitis C virus RNA in liver tissue using a digoxigenin-labeled probe created during a polymerase chain reaction

The cellular localization of hepatitis C virus (HCV) RNA in liver tissue was studied by nonisotopic in situ hybridization using a digoxigenin-labeled cDNA probe created during a polymerase chain reaction on samples from 16 patients with chronic HCV infection. Hybridization signals were recognized in the cytoplasm of the hepatocytes, and a few hepatocytes had hybridization signals in the nucleus as well. HCV RNA positive hepatocytes were found in 1 of 9 patients with chronic persistent hepatitis, 2 of 5 patients with chronic active hepatitis, and in each of 2 patients with chronic active hepatitis and cirrhosis. Positive signals were found in many hepatocytes within the lobule in liver sections of patients with advanced chronic active hepatitis. A number of HCV RNA positive hepatocytes were found in nodules, but not in the area of fibrosis. On the other hand, positive signals were found in a few hepatocytes scattered in the lobule in a patient with chronic persistent hepatitis. The mean ALT levels in the patients with positive signal (175.6 +/- 44.2 U/L) were significantly higher than in those without a signal (70.27 +/- 16.1 U/L) (P < 0.05). The findings suggest that a larger amount of HCV may be present during the advanced than during the early stages of type C hepatitis and nonisotopic in situ hybridization using a digoxigenin-labeled HCV cDNA probe created during a polymerase chain reaction deserves wider application for the detection of HCV replication in specimens.

Serum neopterin levels in ovarian tumors

OBJECTIVES

The aims of this study were to evaluate the difference between benign and malignant ovarian tumors through measurement of preoperative serum neopterin and CA 125 levels and to evaluate the correlation between serum neopterin levels and prognosis.

METHODS

Preoperative serum neopterin levels were measured in 55 ovarian tumors. Of these, 29 malignant tumors were studied over a 3-year follow-up period.

RESULTS

Statistical analysis demonstrated significant differences in neopterin levels between those with benign or malignant ovarian tumors, and different survival rates between the 11 patients whose preoperative neopterin levels were > or = 7.9 nM/l and the 18 patients whose preoperative neopterin levels were < 7.9 nM/l (P < 0.01). The sensitivity of preoperative serum neopterin levels (> or = 7.9 nM/l) in detecting malignant ovarian tumors was 37.9%, the specificity was 96.1%, the positive predictive value 72.0%, the negative predictive value 63.3% and the diagnostic efficiency 65.4%, and those of preoperative serum CA 125 levels (> or = 35 U/ml) in detecting malignant ovarian tumors were 62.1%, 73.1%, 91.7%, 58.1% and 85.5%, respectively.

CONCLUSIONS

Measurement of preoperative serum neopterin levels helped to discriminate between benign and malignant ovarian tumors and was related to ovarian cancer survival. In particular the combination of CA 125 and neopterin measurements showed a better sensitivity for the diagnosis of ovarian cancer than neopterin alone.

Effectiveness of endoscopic ultrasonography in the diagnosis of choledocholithiasis prior to laparoscopic cholecystectomy

BACKGROUND AND STUDY AIMS

To reduce the rate of conversion to open cholecystectomy, and to avoid retained bile duct stones, it is essential to detect choledocholithiasis prior to laparoscopic cholecystectomy. The aim of the present study was to evaluate the usefulness and safety of performing endoscopic ultrasonography (EUS) for the diagnosis of choledocholithiasis prior to laparoscopic cholecystectomy.

PATIENTS AND METHODS

One hundred thirty-two patients with symptomatic cholelithiasis were evaluated prospectively using standard abdominal ultrasonography (US), US plus EUS, and US plus endoscopic retrograde cholangiography (ERC) for the detection of choledocholithiasis prior to laparoscopic cholecystectomy.

RESULTS

Twenty-eight patients (21.2%) had choledocholithiasis, and six patients with common bile duct stones had normal-sized ducts on US. The common bile duct was successfully examined in all patients using EUS, but only in 65.9% of patients when US was used and 94.7% of patients when ERC was used. US plus EUS detected choledocholithiasis in 25 of 28 patients (89.3%), US in 19 of 28 patients (67.9%), and US plus ERC in 26 of 28 patients (92.9%). While no complications as a result of EUS were encountered, complications resulting from ERC occurred in seven patients (5.3%), including cholecystitis in two patients, cholangitis in three patients, and pancreatitis in two patients. In view of the complication and failure rates, EUS appears to offer significant advantages over ERC. These results suggest that EUS is more sensitive than standard abdominal ultrasonography, and as sensitive as ERC.

CONCLUSIONS

EUS appears to be as sensitive as, and safer than, ERC in the detection of choledocholithiasis prior to laparoscopic cholecystectomy.

Influence of dietary medium- and long-chain triglycerides on fat deposition and lipogenic enzyme activities in rats

The present study investigates fat deposition, variances of fatty acid (FA) composition, and lipogenic enzyme activities through dietary medium- and long-chain triglyceride (MCT and LCT) supplementation in growing rats. Eighteen male Wistar rats were divided into three groups and fed isocalorically for 4 weeks with control (based on AIN 76), MCT (C8:0 26%), or LCT (corn oil 25%) diets. Compared to the control group with 0.28 +/- 0.01, feed efficiency was lower in the MCT rats and greater in the LCT rats (0.24 +/- 0.01 and 0.33 +/- 0.01, respectively). Weights of perirenal and epididymal adipose tissue pads of the MCT rats were similar to those of the control group, but were significantly lower than those of the LCT group. Whole-body carcass components data of MCT rats showed the decrease in moisture and protein contents compared to those of control and LCT rats. Fat content of LCT rats was 25-30% higher than those of the MCT and control group. Glucose-6-phosphate dehydrogenase, citrate cleavage enzyme, and malic enzyme activities of liver and epididymal adipose tissue were markedly low in LCT rats. In the MCT group, however, lipogenic enzyme activities were not suppressed, and malic enzyme activity was drastically increased. FA composition of whole-body triglycerides and epididymal adipose tissue in MCT rats showed that C16:0 and C16:1 levels were higher than those of the LCT rats. In contrast, FA composition of the LCT group presented high C18:2 content.(ABSTRACT TRUNCATED AT 250 WORDS)

The influence of dietary medium and long chain triglycerides on growth performances and fat deposition in growing rats

The present study was undertaken to investigate the effects of dietary medium and long chain triglycerides (MCT and LCT) on fat deposition and fatty acid composition of adipose tissues of rats. Twenty-seven Wistar strain male rats were divided into three groups and fed semisynthetic experimental diets: Basal (AIN 76), MCT (basal+C8:0 10%), LCT (basal+corn oil 10%). Feed intake was measured every day and body weight was measured once a week. At the beginning, 4th and 8th week of experimental feeding, 3, 12, 12 rats were slaughtered, respectively. Liver, perirenal and epididymal adipose tissue pads were weighted and their fatty acid composition was determined. Chemical composition of wholebody carcass was measured. Body weight gain was greater in rats fed the LCT diet than in rats fed the basal and MCT diets. Feed intakes were decreased in rats fed the MCT and LCT diets compared to that of the basal group. Subsequently, when compared to the basal group rats, feed efficiencies in rats fed the MCT and LCT diets were improved at the level of 6 and 14% for 4 weeks, and then 17 and 24% for 8 weeks, respectively. The weight of perirenal and epididymal adipose tissue pads tended to be larger in rats fed the MCT and LCT diets than in the basal group, although not significant. There were not significant differences in wholebody composition among the three groups. But it appeared that in rats fed the MCT diet, moisture content tended to be decreased and crude protein content increased compared to the LCT group rats. Fatty acid composition of the rats fed the LCT diet showed a good reflection of dietary fatty acid composition. Unlike LCT, little of medium chain fatty acid (MCFA) itself were incorporated into liver or adipose tissues. However, it seems that fat deposition of the MCT group was accomplished not by incorporation of dietary fatty acids but by de novo fatty acids synthesis.

Measurements of postcoital sympathetic activity in females by means of vanillylmandelic acid

Urinary vanillylmandelic acid (VMA), the final metabolite of epinephrine and norepinephrine, and creatinine (Cr) were measured 1 hr before, within an hour after intercourse, and in a 23-hr pooled sample after intercourse in 11 females. The results were compared to a group of 8 normal females who abstained from intercourse. The control VMA/creatinine ratios were significantly lower than the preintercourse values (P less than 0.01) as well as the postintercourse and 23-hr pooled postintercourse sample. This ratio, 1 hr postintercourse increased significantly (P less than 0.01) over the preintercourse values. The pooled 23-hr postintercourse sample remained high and was significantly different from preintercourse but not from the postintercourse sample. The absolute values of VMA showed relatively similar significance. This study provides objective evidence in the female for the considerable involvement of the sympathetic system during sexual intercourse. In addition, it shows that the group that was planning to have sexual intercourse, 1 hr prior to intercourse, already had VMA/creatinine ratios double over the control group. Such objective information has hitherto not been available.

Elevated creatinine levels in rape assault survivors

Urine specimens were collected from alleged rape survivors. In 13 of the 29 survivors, creatinine levels were over 150 mg/dl, and nine of these were over 200 mg/dl. These elevated urine creatinine levels persisted for some time after the alleged rape attacks. Various controls yielded overall levels below those of the alleged rape assault survivors. When control values of creatinine and osmolality of pre- and postintercourse samples were plotted and compared by linear regression covariance analysis to the data on alleged rape survivors, the levels of urinary creatinine in the alleged rape survivors were higher than would have been expected from urine osmolality increases. The dissimilarity of the two sets of data has a p value less than 0.0001. These findings might serve as supplemental objective evidence of rape (or terror) that could be used medicolegally.