Cytokine array after cyclosporine treatment in rats

OBJECTIVES

Long-term treatment with cyclosporine (CsA) results in chronic nephrotoxicity, which is known to be mediated by several cytokines including transforming growth factor-betal. Cytokines are known to play an important role in innate immunity, apoptosis, angiogenesis, cell growth, and differentiation. They are known to be involved in most disease processes, including cancer, cardiac disease, and nephrotoxicity. To evaluate changes of cytokines in a rat model of CsA-induced chronic nephrotoxicity, we performed a cytokine array.

METHODS

Experiments were performed on two groups of rats; normal control group and CsA-treated group. Cytokine array in rat serum was performed using Cytokine Antibody Array I kit from RayBiotech.

RESULTS

Serum creatinine, urine creatinine, and creatinine clearance increased in the CsA-treated group. Among the several cytokines, the expressions of the lipopolysaccharide-induced CXC chemokine (LIX), monocyte chemoattractant protein 1 (MCP-1), nerve growth factor (beta-NGF), and tissue inhibitor of metalloproteinase-1 (TIMP-1) in the CsA-treated group were increased above that of cytokines in the control group. The density of the LIX in controls was 0.62, and in the CsA-treated group was 1.24. The density of the MCP-1 in controls was 0.68, and in CsA-treated, 1.43. The density of the beta-NGF in controls was 0.62, and that in CsA-treated, 1.24. The density of the TIMP-1 in controls 1.13, and in CsA-treated, 1.40.

CONCLUSIONS

Our data suggested that among several cytokines elevated levels of the LIX, MCP-1, beta-NGF, and TIMP-1 are the contributing factors to CsA-induced nephropathy.

The production of reactive oxygen species in tacrolimus-treated glial cells

OBJECTIVE

After organ transplantation, some patients suffer from mild neurological symptoms, such as tremor, to severe complications, including seizures and encephalopathy. These neurological side effects can be caused by immunosuppressants such as tacrolimus. However, the mechanism of encephalopathy by tacrolimus is not fully understood.

METHODS

We measured the production of reactive oxygen species (ROS) in glioma cells after tacrolimus treatment. Tacrolimus added to glioma cells was incubated for 60 minutes at 37 degrees C. The production of ROS was evaluated by measuring the fluorescent product from the oxidation of an oxidant-sensitive 2',7'-dichlorofluorescin using VICTOR3TM multilabel counter.

RESULTS

Tacrolimus resulted in the production of the ROS in glioma cells. The production of the ROS was increased in time-dependent fashion.

CONCLUSIONS

These findings indicated that the tacrolimus may contribute the neurological side effects by ROS production.

Effect of tacrolimus on the production of oxygen free radicals in hepatic mitochondria

OBJECTIVES

Cyclosporine (CsA) causes side effects that occur mainly in the kidney but also in the liver. Several reports have strongly suggested that the production of oxygen free radicals (OFRs) is a common mechanism of CsA toxicity. However, tacrolimus is believed to suppress the production of OFRs.

METHODS

We obtained the mitochondrial fraction with 96% purity from rat liver using a sucrose density gradient solution. Zero to 100 micromol/L tacrolimus was incubated with the mitochondrial fraction for 6 hours at 37 degrees C. OFRs were evaluated by measuring the fluorescent product from the oxidation of an oxidant-sensitive 2,7-dichlorefluorescein using a VICTOR3 multilabel counter.

RESULTS

The fluorescence units for OFR production were increased as the time of exposure to tacrolimus passed from 1 to 6 hours. The fluorescence units in 0.1 micromol/L tacrolimus were 6.0 x 10(5) at 1 hour, 7.8 x 10(5) at 2 hours, 9.0 x 10(5) at 3 hours, 10.0 x 10(5) at 4 hours, 11.1 x 10(5) at 5 hours, and 11.4 x 10(5) at 6 hours. However, the fluorescence units were similar although the tacrolimus concentration increases from 0.1 to 100 micromol/L.

CONCLUSIONS

The results in this experiment suggested that tacrolimus induced the production of OFRs depending on the exposure time.

Effects of cyclosporine and tacrolimus on the oxidative stress in cultured mesangial cells

OBJECTIVES

Cyclosporine (CsA) and tacrolimus (Tac) are two primary immunosuppressive agents used for the prevention of graft rejection. However, their use is associated with significant side effects, most notably nephrotoxicity. The mechanisms of this toxicity are not fully understood, but they seem to be associated with increases in the production of oxygen free radicals (OFRs). This present work examined the effect of CsA and Tac on the production of OFRs in cultured rat renal mesangial cells (RMCs).

METHODS

Varying concentrations of CsA and Tac (0 to 40 micromol/L) were added to RMCs and incubated for 60 minutes at 37 degrees C. The production of OFRs was evaluated by measuring the fluorescent product from the oxidation of an oxidant-sensitive 2', 7'-dichlorofluorescin.

RESULTS

At 60 minutes, the relative fluorescence units (RFU) for OFRs production in RMCs exposure to CsA were increased by 2.5%, 11.5%, 22.5%, 57.2%, and 174% at 2.5, 5, 10, 20, and 40 micromol/L, respectively. Tac increased the RFU by 15.9%, 13.6%, 14.8%, 13.2%, 21.4%, 13.2%, and 28.1% at 0.1, 1, 2.5, 5, 10, 20, and 40 micromol/L, respectively. In RMCs, the RFU produced by CsA was higher than that by Tac.

CONCLUSIONS

The results of this experiment suggest that CsA and Tac induced renal injury by OFRs.

Phase contrast radiography of Lewy bodies in Parkinson disease

Parkinson's disease (PD), defined as a neurodegenerative disorder, is characterized by the loss of dopaminergic neurons and the presence of Lewy bodies in neurons. Morphological study of Lewy bodies is important to identify the causes and the processes of PD. Here, we investigate a possibility of phase contrast radiography using coherent synchrotron X-rays to explore the microscopic details of Lewy bodies in thick (approximately 3 mm) midbrain tissues. Autopsied midbrain tissues of a PD patient were sliced in 3 mm thickness and then examined using synchrotron X-rays from the 7B2 beamline of the Pohang Light Source. Refraction-enhanced phase contrast radiography and microtomography were adopted to identify dark core and dim edge of Lewy bodies in neurons. The morphology of Lewy bodies was clearly revealed by the phase contrast radiography in very thick (3 mm) midbrain tissues without any staining treatment. Three-dimensional volume rendered microtomography of the autopsied midbrain tissues demonstrates striking evidence that several Lewy bodies are agglomerated by dim edges in a neuron. We suggest that the phase contrast radiography could be a useful tool to morphologically investigate the causes or the processes in PD.

Simultaneous Bilateral Carotid Stenting under the Circumstance of Neuroprotection Device. A Retrospective Analysis

SUMMARY

In this study, in order to evaluate the feasibility and outcomes of simultaneous bilateral carotid artery stenting (CAS) with the use of neuroprotection in symptomatic patients, we conducted a retrospective analysis of 27 patients (19 men, eight women; median age, 69.2 years), all of whom had been scheduled to undergo bilateral CAS in a single setting. All patients presented with severe atherosclerotic bilateral carotid stenosis (> 50% for symptomatic side, > 80% for asymptomatic side), exhibiting symptoms of either a cerebrovascular accident or of a transient ischemic attack on at least one side. 48 arteries were treated with self-expandable stents. Neuroprotection devices were utilized for bilateral CAS in 11 patients, and in 16 unilateral CAS patients. We did not perform the second procedure in six patients, in cases in which a patient exhibited (a) hemodynamic instability, (b) a new neurological impairment, or (c) restlessness after a prolonged time for the first CAS. The second procedure was postponed in a staged manner. We achieved a mean residual stenosis of 8.1 +/- 5.0 % in the treated lesions. The mean procedural time for bilateral CAS was three hours and 18 minutes. 17 patients (63%) developed transient bradycardia during the balloon dilatation of one or both of the relevant arteries. Three patients (11%) exhibited persistent bradycardia and hypotension, which required the administration of intravenous vasopressors for several days (2~7 days). None of the patients ultimately required pacemakers, or any further therapy. Two of the patients (7%) developed transient ischemic attack during the periprocedural period, but recovered completely. One patient developed a new minor stroke after the first procedure, and the second procedure was delayed in a staged manner.We observed no periprocedural deaths, major strokes, or myocardial infarctions, nor did we detect any cases of hyperperfusion syndrome within 30 days. In summary, simultaneous bilateral CAS with neuroprotection can be performed in a single setting without increased concerns with regard to hyperperfusion syndrome, hemodynamic instability, thrombo-embolism, or procedure time, when the first CAS has been safely completed with no evidence of complications in a wellmanaged procedure time.

Effects of polyhemoglobin-antioxidant enzyme complex on ischemia-reperfusion in kidney

INTRODUCTION

The kidney suffers ischemia-reperfusion (I/R) injury during transplantation. The purpose of the present study was to investigate the therapeutic effect of artificials cells on renal I/R injury through biochemical assays and histological examination.

METHODS

We prepared artificial cells using cross-linked hemoglobin (Hb), superoxide dismutase (SOD), and catalase. Normal male Sprague-Dawley rats were divided into 6 groups: the sham-operated control group, the group treated with polyHb,and the group treated with polyHb-SOD-catalase (PSC) (per groups were subjected to ischemia for 1 hour or 2 hours). After reperfusion for 4 hours, kidney and blood samples were obtained.

RESULTS

The levels of SOD and catalase in the PSC group were 15 and 50 times higher than those of the control group, respectively. In the polyHb group, the levels of blood urea nitrogen (BUN), serum creatinine, renal hydrogen peroxide, and renal malondialdehyde were increased. However, their levels were significantly decreased by PSC administration. Renal SOD activity did not show any significant changes in the polyHb group, but renal catalase activity was decreased by polyHb treatment in comparison with the control group. The activities of renal SOD and catalase were increased using PSC treatment. In the histological findings, the PSC group showed no evidence of acute tubular necrosis in proximal convoluted tubules; their microvilli and cytoplasmic microorganelles were relatively well preserved.

CONCLUSIONS

These results show that PSC effectively reduces renal damage via diminished oxygen free radical-mediated injury after I/R.

Effect of artificial cells on hepatic function after ischemia–reperfusion injury in liver

BACKGROUND

The liver suffers from ischemia/reperfusion injury during transplantation. Reactive oxygen species generated by xanthine oxidase during reperfusion of the ischemic liver may be partially responsible for the hepatic injury. Oxygen free radicals are removed by antioxidant enzymes such as superoxide dismutase (SOD), catalase, and glutathione peroxidase. Using glutaraldehyde and lysine we constructed crosslinked hemoglobin, containing SOD and catalase, and assessed its ability to protect against ischemia/reperfusion injury during transplantation.

METHODS

In contrast to the sham-operated control groups, blood was exchanged using crosslinked hemoglobin (polyHb) a PolyHb-SOD-catalase (PSC) group. After ischemia/reperfusion injury, several parameters of hepatic damage and oxygen free radicals were measured as well as microscopic examination.

RESULTS

Alanine aminotransferase, aspartate aminotransferase, superoxide production, hydrogen peroxide, and malondialdehyde levels were higher among the PolyHb group than sham-operated controls. The PolyHb group revealed a few apoptotic bodies, some acute inflammatory infiltrates in the sinusoids, nuclear fragmentations, cell shrinkage, and chromatin clumping with formation of apoptotic bodies in the apoptotic cells under microscopic examination. Alanine aminotransferase, aspartate aminotransferase, superoxide production, and hydrogen peroxide levels were lower in the PSC than the PolyHb group. Hepatic structures were well preserved in the PSC group.

CONCLUSIONS

Reactive oxygen species contribute to hepatic dysfunction with morphologic changes. PSC is effective to reduce hepatic damage by lowering oxygen free radical-mediated injury after ischemia/reperfusion in the liver.

The green tea polyphenol (-)-epigallocatechin gallate attenuates beta-amyloid-induced neurotoxicity in cultured hippocampal neurons

Previous evidence has indicated that the neuronal toxicity of amyloid beta (betaA) protein is mediated through oxygen free radicals and can be attenuated by antioxidants and free radical scavengers. Recent studies have shown that green tea polyphenols reduced free radical-induced lipid peroxidation. The purpose of this study was to investigate whether (-)-epigallocatechin gallate (EGCG) would prevent or reduce the death of cultured hippocampal neuronal cells exposed to betaA because EGCG has a potent antioxidant property as a green tea polyphenol. Following exposure of the hippocampal neuronal cells to betaA for 48 hours, a marked hippocampal neuronal injuries and increases in malondialdehyde (MDA) level and caspase activity were observed. Co-treatment of cells with EGCG to betaA exposure elevated the cell survival and decreased the levels of MDA and caspase activity. Proapoptotic (p53 and Bax), Bcl-XL and cyclooxygenase (COX) proteins have been implicated in betaA-induced neuronal death. However, in this study the protective effects of EGCG seem to be independent of the regulation of p53, Bax, Bcl-XL and COX proteins. Taken together, the results suggest that EGCG has protective effects against betaA-induced neuronal apoptosis through scavenging reactive oxygen species, which may be beneficial for the prevention of Alzheimer's disease.

p21(WAF1) is associated with CDK2 and CDK4 protein during HL-60 cell differentiation by TPA treatment

TPA-treated HL-60 cells are mainly arrested in G1 by p21(WAF1) accumulation. We investigate the downstream changes following such accumulation. Increased p21(WAF1) is associated with CDK2 and CDK4. pRb is dephosphorylated in the presence of p21-CDK2/4 complexes, and the Rb-E2F1 complex increases after TPA treatment, whereas the Rb-HDAC1 complex decreases slightly. Our results suggest that increased p21(WAF1) is associated with CDK2/4, and that these complexes induce pRb dephosphorylation. In turn, hypophosphorylated pRb are mainly complexed with E2F1, but HDAC1 appears not to be a key component in this process.

The effects of the melatonin on ultraviolet-B irradiated cultured dermal fibroblasts

It has been reported that reactive oxygen species (ROS) and oxygen-derived free radicals are generated by ultraviolet (UV) radiation and various chemicals and their important roles in cellular damage and apoptosis are being increasingly recognized. Melatonin is a hormone with multiple functions in humans, produced by the pineal gland and stimulated by beta-adrenergic receptors. Melatonin has been shown to have photo protection properties, but there has been little progress toward identifying the specific mechanisms of its action. To clarify the role of melatonin as a free radical scavenger, in response to ultraviolet-B (UVB) irradiation, we investigated the effects of UVB and melatonin on cytotoxicity, lipid peroxidation, terminal deoxynucleotidyl transferase-mediated digoxigenin-dUTP nick end-labeling (TUNEL) assay and alteration of cell cycle in cultured skin fibroblast. Cell survival curves after UVB irradiation showed dose dependent decrement pattern by trypan blue exclusion assay. Only 56% of dermal fibroblasts were survived at 140 mJ/cm2 UVB irradiation. The damage was associated with cell membrane lipid peroxidation, as shown by accumulation malondialdehyde (MDA). By pre-cultivation with melatonin (10(-9) M), a significant preventive effect was noted on the increase in the absolute number of surviving cells (up to 92.5% of cells were survived) and the levels of MDA were markedly decreased. These finding suggest significant correlation between an increase of lipid peroxide and cell viability. Morphological changes associated with apoptotic cell death were easily distinguished by TUNEL stain. Quantitative analysis of DNA content of skin fibroblasts was evaluated by flow cytometric analysis performed after vital staining with propidium iodide. UVB suppresses the G1 progression induced pre-G1 arrest leading to apoptotic changes of dermal fibroblast and those are blocked by melatonin pre-treatment. The results show the photodynamic effects of UVB that supposes the production of ROS and arrest the cell cycle. Melatonin, which have newly accepted as a potential UV protection properties, is effective membrane peroxidation inhibitor and prevent the pre-G1 arrest when present in relevant concentration during UVB irradiation.

Bcl-2 overexpression attenuates resveratrol-induced apoptosis in U937 cells by inhibition of caspase-3 activity

Resveratrol has been shown to induce anti-proliferation and apoptosis of human cancer cell lines. In the present study, we determined the effect of high intracellular levels of the anti-apoptosis protein Bcl-2 on caspase-3 activation, PLC-gamma1 degradation and cytochrome c release during resveratrol-induced apoptosis. For this, we used U937/vector and U937/Bcl-2 cells, which were generated by transfection of the cDNA of the Bcl-2 gene. As compared with U937/vector, U937/Bcl-2 cells exhibited a 4-fold greater expression of Bcl-2. Treatment with 60 or 100 microM resveratrol for 24 h produced morphological features of apoptosis and DNA fragmentation in U937/vector cells, respectively. This was associated with caspase-3 activation and PLC-gamma1 degradation. In contrast, resveratrol-induced caspase-3 activation and PLC-gamma1 degradation and apoptosis were significantly inhibited in U937/Bcl-2 cells. Bcl-2 overexpressing cells exhibited less cytochrome c release and sustained expression levels of the IAP proteins during resveratrol-induced apoptosis. In addition, these findings indicate that Bcl-2 inhibits resveratrol-induced apoptosis by a mechanism that interferes with cytochrome c release and activity of caspase-3 that is involved in the execution of apoptosis.

Involvement of ERK and protein tyrosine phosphatase signaling pathways in EGCG-induced cyclooxygenase-2 expression in Raw 264.7 cells

Prostaglandins play regulatory roles in a variety of physiological and pathological processes in immune response and inflammation. Epigallocatechin-3-gallate (EGCG) is known to potent antitumor agent with antioxidant property. We first investigated the effect of EGCG on the production of prostaglandin E(2) (PGE(2)) and the expression of cyclooxygenase-2 (COX-2), the rate-limiting enzyme in the synthesis of PGE(2), using macrophage cell line, Raw264.7. Our results showed that COX-2 expression and PGE(2) production are upregulated by EGCG treatment and that this induction of COX-2 is regulated in part at the transcriptional level. In addition, we demonstrated the signal transduction pathway of mitogen-activated protein kinase (MAP kinase) in EGCG-mediated COX-2 expression. The MEK inhibitor (PD098059) prevented EGCG-induced COX-2 expression, whereas sodium orthovanadate (protein-tyrosine phosphatase inhibitor) significantly enhanced COX-2 expression and PGE(2) production. These results suggest that EGCG mediated COX-2 expression and PGE(2) production is associated with the activation of both the ERK and protein-tyrosine phosphatase signaling pathways.

Immune response induced by immunization with Hepatitis B virus core DNA isolated from chronic active hepatitis patients

There are many mutations in the gene encoding Hepatitis B virus (HBV) core antigen of chronic active hepatitis patients, and such mutations are most likely to be related to the severity of disease. Here, we constructed plasmids containing wild-type and deletion type of HBV core gene (HBc) to develop an experimental DNA vaccine and to compare immunogenicity of two types of HBc vaccine. Twenty-nine wild-types and seven deletion types of HBc were detected in sera of 32 Korean patients with chronic active hepatitis. Four wild-types (W1, W2, W4, W6) and two deletion types (D3, D4) of HBc were cloned into the pcDNA3 vector. Intramuscular immunization with wild-type HBc efficiently increased serum anti-HBc antibody response in a dose-dependent manner. Anti-HBc antibody response in mice injected with W6 increased 14 days after immunization, and peaked after 30 days and was maintained at least up to 50 days. W6 immunization induced a specific cytotoxic T lymphocyte response to W6-transfected 3LL (3LL-W6), and reduced the sizes of tumor mass of mice challenged with 3LL-W6 or 3LL transfected with D4. However, intramuscular immunization with D3 and D4 did not show antibody response at all. D3 and D4 have 157 bp (from 331 to 491 bp) and 122 bp (from 327 to 448 bp) gene deletion, respectively, and these encode class II MHC-restricted T-cell epitope. Altogether, these results suggest that mutant virus that has deleted HBc gene may evade immune systems due to loss of T-cell epitope.

Hepatitis C virus core protein promotes cell proliferation through the upregulation of cyclin E expression levels

AIMS/BACKGROUND

The hepatitis C virus (HCV) core protein is known to play an important role in hepatocarcinogenesis. Recent studies have suggested that the increased proliferation rate of hepatocytes is a major risk factor for the development of hepatocellular carcinoma. In this study, we investigated whether the HCV core protein promotes the cell growth rate through the modulation of cyclin E expression levels.

METHODS/RESULTS

HCV core stable transfectant Rat-1 cell lines showed a markedly increased proliferation rate compared to mock cells. Cyclin E expression and its associated kinase activities were remarkably increased in HCV core stable transfectants. Cyclin E mRNA levels were also upregulated in these cell lines.

CONCLUSIONS

Our data suggest that the HCV core protein promotes cell proliferation through upregulation of the cyclin E expression levels, implying this property of HCV core protein plays an important role in hepatocarcinogenesis.

The levels of MDM2 protein are decreased by a proteasome-mediated proteolysis prior to caspase-3-dependent pRb and PARP cleavages

MDM2 is a substrate of caspase-3 in p53-mediated apoptosis. In addition, MDM2 mediates its own ubiquitination in a RING finger-dependent manner. Thus, we investigated whether MDM2 is degraded through a ubiquitin-dependent proteasome pathway in the absence of p53. When HL-60 cells, p53 null, were treated with etoposide, MDM2 was markedly decreased prior to caspase-3-dependent retinoblastoma tumor suppressor protein (pRb) and poly (ADP- ribose) polymerase (PARP) cleavages. Moreover, down-regulation of MDM2 level was not coupled with its mRNA down-regulation. However, the level of MDM2 was partially restored by proteasome inhibitors such as LLnL and lactacystin, even in the presence of etoposide. Our results suggest that, in the p53 null status, MDM2 protein level is decreased by proteasome-mediated proteolysis prior to caspase-3-dependent PARP and pRb cleavages.

Chemopreventive agent resveratrol, a natural product derived from grapes, reversibly inhibits progression through S and G2 phases of the cell cycle in U937 cells

Resveratrol, a natural product derived from grapes, has been shown to prevent carcinogenesis in murine models. We report here that resveratrol induces antiproliferation and arrests the S phase in human histiocytic lymphoma U937 cells. Resveratrol induces arrest in the S phase at low concentrations (30-60 microM), but high concentrations do not induce S phase accumulation in U937 cells. Removal of resveratrol from the culture medium stimulates U937 cells to reenter the cell cycle synchronously, as judged by the expression patterns of cyclin E, A and by fluorescent activated cell sorting analysis. These data demonstrate that resveratrol causes S phase arrest and reversible cell cycle arrest. Thus, resveratrol provides an important new cell cycle blocker as well as a cancer chemopreventive agent.

5-Aza-2'-deoxycytidine leads to down-regulation of aberrant p16INK4A RNA transcripts and restores the functional retinoblastoma protein pathway in hepatocellular carcinoma cell lines

The inactivation of the cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitor p16INK4A may be caused by gene deletion, mutation or promoter hypermethylation. We have previously reported that p16INK4A in hepatocellular carcinoma (HCC) tissues and cell lines is inactivated predominantly by promoter hypermethylation rather than genomic aberrations. In the present experiments, we have studied the effects of the demethylating agent, 5-aza-2'-deoxycytidine (5-AZA/decitabine), on the expression of aberrant p16INK4A RNA transcripts and the CDK-retinoblastoma gene pathway in HCC cell lines with p16INK4A promoter hypermethylation. The expression of aberrant p16INK4A RNA transcripts was down-regulated and p16INK4A protein was strongly re-expressed in the HCC cell lines, SNU 354, 398, 423 and 475 after 5-AZA/decitabine treatment for 5 days. The re-expressed p16INK4A was functional, because it bound to and inhibited CDK4 kinase activity, and increased the concentrations of the hypophosphorylated form of retinoblastoma protein (pRB) in cells with a wild type RB gene. Moreover, treatment with the demethylating agent led not only to G1 cell cycle arrest, but also to the increased expression of the senescence-associated marker beta-galactosidase. This up-regulation of p16INK4A mRNA and protein correlated with demethylation of the p16INK4A promoter, and with the down-regulation or disappearance of aberrant p16INK4A transcripts. These results suggest that the aberrant p16INK4A RNA transcript can be transcribed from the methylated p16INK4A gene, and endogenous reactivation of functional p16INK4A mRNA by a demethylating agent can restore the pRB pathway in HCC, and foster the terminal differentiation of the malignant cells. Therefore, demethylating agents, such as 5-AZA/decitabine, may have potential in the treatment of HCC.

Lack of mutation at p16INK4A gene but expression of aberrant p16INK4A RNA transcripts in human ovarian carcinoma

Alterations of the p16INK4A gene are frequent in various human cancers. We investigated p16INK4A gene status in 20 ovarian carcinomas by PCR (polymerase chain reaction), PCR-SSCP (polymerase chain reaction-single strand conformation polymorphism) and sequencing techniques. None of the primary tumors showed any mutational or deletional events. However, 19 out of 20 tumors displayed both a methylated and an unmethylated p16INK4A promoter. In some of these samples, we detected aberrant p16INK4A transcripts, with partial deletions of both exons 1 and 2, which could not encode a functional p16INK4A protein. The sequences of the aberrant mRNA revealed common 4-7 nucleotide sequences before and after the deleted region, which might cause abnormal splicing of mRNA transcripts. These results suggest that both promoter methylation and aberrant mRNA processing may interfere with p16INK4A expression in ovarian tumors.

p53 codon 72 polymorphism and risk of cervical carcinoma in Korean women

A common polymorphism of the wild type p53 is known at codon 72 of exon 4, with 2 alleles encoding either arginine (CGC, p53Arg) or proline (CCC, p53Pro). A recent study suggested that this polymorphism affects the susceptibility of p53 protein to human papillomavirus E6 oncoprotein mediated degradation and that individuals homozygous for p53Arg are seven times more susceptible to HPV-associated carcinogenesis of the cervix than heterozygotes. To examine whether the p53Arg genotype could be a risk factor for HPV-associated cervical carcinomas in the Korean population, we analyzed the p53 codon 72 polymorphism status of HPV-positive invasive cervical carcinomas from 52 Korean women and 103 healthy control samples. The proportion of individuals homozygous for p53Arg, homozygous for p53Pro, and heterozygous for the two alleles were 40%, 19%, and 41% in normal healthy controls; 42%, 17%, and 40% in women with HPV-positive invasive cervical carcinoma. There were no significant differences in the distribution of p53 genotypes between controls and cervical carcinomas. This finding indicates that the p53Arg genotype is not associated with an increased susceptibility to cervical carcinoma in Korean women.

Persistent expression of Fas/FasL mRNA in the mouse hippocampus after a single NMDA injection

Synaptic reorganization plays a very important role in brain adaptations to environmental stimuli, diseases, and aging processes. The NMDA model of excitotoxic injury was used to investigate the long-term molecular changes in the surviving neural cells in the mouse hippocampus. We demonstrated that a single intraperitoneal injection of NMDA produces persistent expression of c-fos, c-jun, Fas, and Fas ligand (FasL) mRNA in the hippocampus for 5 months. To determine the cellular origin of those gene transcripts in our in vivo model, a glial cell line and primary fetal neuronal culture were used to investigate the inducibility of the c-fos, c-jun, Fas, and FasL mRNA by NMDA. Both c-fos and Fas mRNA expression was observed in the NMDA-treated glial or neuronal cultures; however, c-jun and FasL mRNA was undetectable in this study. In our in vivo model, mossy fiber sprouting and apoptosis were also observed up to 40 days after the NMDA injection. Therefore, we hypothesize that the observed long-term expression of c-fos, c-jun, Fas, and FasL mRNAs may reflect the ongoing synaptic reorganization.

Identification of CD44 splice variant in Korean colorectal cancers and cell lines

CD44 is a glycoprotein expressed in a wide variety of cell types. Recently expression of some alternatively-spliced variants of CD44 transcripts (CD44v) has been suggested to play a potential role in tumor metastasis and the detection of CD44v containing exon 6 to 11 may be helpful for the diagnosis of cancers. Expressions of CD44v containing exon 6 to 11 were investigated in 20 human colorectal cancer samples, peripheral blood leukocytes isolated from colorectal cancer patients, and 4 colorectal cancer cell lines using reverse transcription-polymerase chain reaction and Southern blot analysis. The standard form of CD44 transcripts was expressed in all samples tested. CD44v containing exon 6 to 11 was expressed in 18 cases of colorectal cancers (sensitivity = 90%), 3 out of 4 cell lines, and one normal tissue (specificity = 95%). These results suggest that the expression of CD44v containing exon 6 to 11 can be regarded as tumor specific and that this marker may be helpful for the early diagnosis of colon cancers, if specimens from the early stage are available.