Distinct patterns of protein binding to the MAT2A promoter in normal and leukemic T cells.

The metabolism of S-adenosylmethionine (AdoMet), a key molecule in regulating T cell differentiation and proliferation, is different in normal and leukemic T cells. To delineate the basis for these differences we studied the transcriptional regulation of human methionine adenosyltransferase II (MAT II), which catalyzes AdoMet synthesis in these cells. Recently, we identified an Sp1 site in the proximal promoter of the MAT2A gene, which encodes the alpha2 catalytic subunit of MAT II, that is essential for the in vitro and in vivo promoter activity in Jurkat leukemic T cells, and that involves binding of the nuclear factors Sp2 and Sp3, but not Sp1. Here, the in vitro and in vivo activity of the proximal MAT2A promoter in normal resting, PHA-stimulated, and leukemic human T cells was compared. Significantly different patterns of protein factor interaction in the proximal region of the MAT2A promoter were found. Normal resting and activated T cells produced complexes of significantly lower molecular weight than those formed in leukemic T cells. Supershift studies coupled with analysis of proteins bound to the proximal promoter suggest that low levels of expression of Sp2 and Sp3 in normal T cells may be responsible for the difference in the in vitro promoter activity between normal and leukemic cells. Mutation of the key Sp1 site equally reduced the in vivo promoter activity in normal and malignant T cells; by contrast, it had significantly different effects on protein-DNA interactions in normal and leukemic T cells. Together, the data support the idea that differences in protein-DNA interactions may contribute to significant differences in MAT2A regulation in normal and malignant cells.

Reciprocal, temporal expression of SpeA and SpeB by invasive M1T1 group a streptococcal isolates in vivo.

The streptococcal pyrogenic exotoxins (Spes) play a central role in the pathogenesis of invasive group A streptococcal (GAS) infections. The majority of recent invasive GAS infections have been caused by an M1T1 strain that harbors the genes for several streptococcal superantigens, including speA, speB, speF, speG, and smeZ. However, considerable variation in the expression of Spe proteins among clonal M1 isolates has been found, and many of the speA-positive M1 strains do not produce detectable amounts of SpeA in vitro. This study was designed to test the hypothesis that speA gene expression can be induced in vivo. A mouse infection chamber model that allows sequential sampling of GAS isolates at various time points postinfection was developed and used to monitor the kinetics of Spe production in vivo. Micropore Teflon diffusion chambers were implanted subcutaneously in BALB/c mice, and after 3 weeks the pores became sealed with connective tissue and sterile fluid containing a white blood cell infiltrate accumulated inside the infection chambers. Representative clonal M1T1 isolates expressing no detectable SpeA were inoculated into the implanted chambers, and the expression of SpeA in the aspirated aliquots of the chamber fluid was analyzed on successive days postinfection. Expression of SpeA was detected in the chamber fluid as early as days 3 to 5 postinfection in most animals, with a significant increase in expression by day 7 in all infected mice. Isolates recovered from the chamber and grown in vitro continued to produce SpeA even after 21 passages in vitro, suggesting stable switch on of the speA gene. A temporal relation between the upregulation of SpeA expression and the downregulation of SpeB expression was observed in vivo. These data suggest that in vivo host and/or environmental signals induced speA gene expression and suppressed speB gene expression. This underscores the role of the host-pathogen interaction in regulating the expression of streptococcal virulence factors in vivo. The model described here should facilitate such studies.

Regulation of the human MAT2B gene encoding the regulatory beta subunit of methionine adenosyltransferase, MAT II.

Methionine adenosyltransferase (MAT) catalyzes the biosynthesis of S-adenosylmethionine (AdoMet), a key molecule in transmethylation reactions and polyamine biosynthesis. The MAT II isozyme consists of a catalytic alpha2 and a regulatory beta subunit. Down-regulation of the MAT II beta subunit expression causes a 6-10-fold increase in intracellular AdoMet levels. To understand the mechanism by which the beta subunit expression is regulated, we cloned the MAT2B gene, determined its organization, characterized its 5'-flanking sequences, and elucidated the in vitro and in vivo regulation of its promoter. Transcription of the MAT2B gene initiates at position -203 relative to the translation start site. Promoter deletion analysis defined a minimal promoter between positions +52 and +93 base pairs, a GC-rich region. Inclusion of the sequences between -4 and +52 enhanced promoter activity; this was primarily because of an Sp1 recognition site at +9/+15. The inclusion of sequences up to position -115 provided full activity; this was attributed to a TATA at -32. The Sp1 site at position +9 was key for the formation of protein.DNA complexes. Mutation of both the Sp1 site at +9 and the TATA at -32 reduced promoter activity to its minimal level. Supershift assays showed no effect of the anti-Sp1 antibody on complex formation, whereas the anti-Sp3 antibody had a strong effect on protein.DNA complex formation, suggesting that Sp3 is one of the main factors binding to this Sp1 site. Chromatin immunoprecipitation assays supported the involvement of both Sp1 and Sp3 in complexes formed on the MAT2B promoter. The data show that the 5'-untranslated sequences play an important role in regulating the MAT2B gene and identifies the Sp1 site at +9 as a potential target for modulating MAT2B expression, a process that can have a major effect on intracellular AdoMet levels.

Regulation of the human MAT2A gene encoding the catalytic alpha 2 subunit of methionine adenosyltransferase, MAT II: gene organization, promoter characterization, and identification of a site in the proximal promoter that is essential for its activity.

Mammalian methionine adenosyltransferase II (MAT II) consists of a catalytic alpha2/alpha2' and a regulatory beta subunit. Up-regulation of alpha2 subunit expression is associated with increased intracellular levels of S-adenosylmethionine, the major methyl group donor and a key compound in cell metabolism and polyamine synthesis. Previous studies have shown that expression of the alpha2 subunit is differentially regulated in normal and malignant cells. To delineate the molecular basis for the differential regulation of alpha2 subunit expression, we cloned and characterized the human MAT2A gene and its promoter and defined regions that contain enhancer and repressor elements. Detailed functional characterization of the proximal promoter of the MAT2A gene revealed the formation of three major protein-DNA complexes with probes containing three Sp1 sites (Sp1-1 at -14, Sp1-2 at -47, and Sp1-3 at -69). Competition with a probe copying sequence between -76 and -54, which contains the Sp1-3 site only, or mutation of this site, abolished complex formation. Furthermore, mutation of the Sp1-3 site, but not the Sp1-1 or Sp1-2 sites, inhibited the in vivo promoter activity by approximately 85%. Supershift assays showed that the transcription factors Sp2 and Sp3 are part of the complexes formed at the Sp1-3 site, and that Sp1 does not appear to be directly involved. The data indicate that complex formation is initiated at site Sp1-3, which appears to be essential for promoter activity. However, other regions of the proximal promoter may also contribute to the regulation of MAT2A gene expression. These studies may lead to the delineation of the molecular basis for the differential regulation of MAT2A expression in normal and leukemic T cells.

Cloning, expression, and functional characterization of the beta regulatory subunit of human methionine adenosyltransferase (MAT II).

MAT II, the extrahepatic form of methionine adenosyltransferase (MAT), consists of catalytic alpha(2)/alpha(2') subunits and a noncatalytic beta subunit, believed to have a regulatory function. The full-length cDNA that encodes the beta subunit of human MAT II was cloned and found to encode for a 334-amino acid protein with a calculated molecular weight of 37,552. Analysis of sequence homology showed similarity with bacterial enzymes that catalyze the reduction of TDP-linked sugars. The beta subunit cDNA was cloned into the pQE-30 expression vector, and the recombinant His tagged protein, which was expressed in Escherichia coli, was recognized by antibodies to the human MAT II, to synthetic peptides copying the sequence of native beta subunit protein, and to the rbeta protein. There is no cross-reactivity between the MAT II alpha(2) or beta subunits. None of the anti-beta subunit antibodies reacted with protein extracts of E. coli host cells, suggesting that these bacteria have no beta subunit protein. Interestingly, the rbeta subunit associated with E. coli as well as human MAT alpha subunits. This association changed the kinetic properties of both enzymes and lowered the K(m) of MAT for L-methionine. Together, the data show that we have cloned and expressed the human MAT II beta subunit and confirmed its long suspected regulatory function. This knowledge affords a molecular means by which MAT activity and consequently the levels of AdoMet may be modulated in mammalian cells.

Expression and functional interaction of the catalytic and regulatory subunits of human methionine adenosyltransferase in mammalian cells.

Methionine adenosyltransferase (MAT) catalyzes the synthesis of S-adenosylmethionine (AdoMet). The mammalian MAT II isozyme consists of catalytic alpha(2) and regulatory beta subunits. The aim of this study was to investigate the interaction and kinetic behavior of the human MAT II subunit proteins in mammalian cells. COS-1 cells were transiently transfected with pTargeT vector harboring full-length cDNA that encodes for the MAT II alpha(2) or beta subunits. Expression of the His-tagged recombinant alpha(2) (ralpha(2)) subunit in COS-1 cells markedly increased MAT II activity and resulted in a shift in the K(m) for L-methionine (L-Met) from 15 microM (endogenous MAT II) to 75 microM (ralpha(2)), and with the apparent existence of two kinetic forms of MAT in the transfected COS-1 cell extracts. By contrast, expression of the recombinant beta (rbeta) subunit had no effect on the K(m) for L-Met of the endogenous MAT II, while it did cause an increase in both the V(max) and the specific activity of endogenous MAT. Co-expression of both ralpha(2) and rbeta subunits resulted in a significant increase of MAT specific activity with the appearance of a single kinetic form of MAT (K(m) = 20 microM). The recombinant MAT II alpha(2) and rbeta subunit associated spontaneously either in cell-free system or in COS-1 cells co-expressing both subunits. Analysis of nickel-agarose-purified His-tagged ralpha(2) subunit from COS-1 cell extracts showed that the beta subunit co-purified with the alpha(2) subunit. Furthermore, the alpha(2) and beta subunits co-migrated in native polyacrylamide gels. Together, the data provide evidence for alpha(2) and beta MAT subunit association. In addition, the beta subunit regulated MAT II activity by reducing its K(m) for L-Met and by rendering the enzyme more susceptible to feedback inhibition by AdoMet. We believe that the previously described differential expression of MAT II beta subunit may be an important mechanism by which MAT activity can be modulated to provide different levels of AdoMet that may be required at different stages of cell growth and differentiation.

The clinical value of CYFRA21-1 in bladder cancer patients: Egyptian experience.

There are a wide variety of tumor markers now available that proved to be of value in the management of cancer patients. Of these markers, tissue polypeptide antigen (TPA) and tissue polypeptide specific antigen (TPS) are well known in the field of bladder cancer. TPA was found to be a mixture of cytokeratins 8, 18 and 19 and recent investigations proved that TPS is keratin 18. The aim of the present study was to assess the clinical value of urinary cytokeratin 19 (CYFRA21-1) in the differential diagnosis between bladder cancer and benign urinary tract diseases represented by bilharziasis. Two hundreds and seventy individuals were included in the present study: 186 with bladder cancer representing the different stages and grades, 44 with urinary tract bilharziasis and 40 normal healthy controls. CYFRA21-1 was evaluated in 24-hour urine samples by ELISA using the automatic set supplied by Boehringer Manheim, Manheim, Germany (ES 300). Results of this study revealed significant elevation of CYFRA21-1 in bladder cancer followed by bilharziasis. 82.3% (153/186) of bladder cancer patients and 11.4% (5/44) of bilharzial patients exhibited CYFRA21-1 levels above the upper limit of the control group (3 micrograms/24-hr). CYFRA21-1 was more sensitive in advanced than early stages of bladder cancer and in patients with positive than those with negative lymph nodes, but association of tumor with bilharziasis did not markedly affect its level.

Effect of schistosomiasis and hepatitis on liver disease.

Infection with hepatitis C virus (HCV) has become the most important public health problem in Egypt. In Egypt, viral hepatitis along with infection with Schistosoma mansoni is the major cause of chronic liver disease and liver cirrhosis. Although HCV infection is highly prevalent in Egypt, very little information is available on the distribution of the different genotypes of HCV. Our aims in this study were first to determine the prevalence of viral and parasite infections in patients with chronic liver disease and then to assess the distribution of HCV genotypes in these patients. In the present study, 151 individuals (50 with chronic liver disease, 51 with chronic diseases of organs other than the liver, and 50 apparently healthy persons) were investigated. The last 2 groups served as control groups. These individuals were subjected to routine liver function tests and detection of serum antibodies to bilharziasis, hepatitis B surface antigen (HBsAg), and HCV. Furthermore, the presence of hepatitis G virus (HGV) and HCV in the serum samples were tested for by a reverse transcription polymerase chain reaction (RT-PCR). Prevalence of different genotypes of HCV in patients positive for HCV were determined by RT-PCR using type-specific primers. Results of the study revealed that 84, 74, 12, and 20% of patients with chronic liver disease were positive for Schistosoma mansoni, HCV, HBsAg, and HGV, respectively, as compared to 51, 43.1, 2, and 4% of patients with other chronic diseases and 22, 6, 0, and 0% of apparently healthy individuals. One hundred percent of patients with chronic liver disease, 72.5% of those with other diseases, and 26% of normal controls were shown to have at least one of the studied infectious agents. Two or more of the agents were highly coincident in patients with chronic liver disease. In Egypt, HCV genotype 4a is highly prevalent, where it contributed 85% of the tested samples in comparison to 10, 2.5, and 2.5% for subtypes 1b, 2a, and 3a, respectively. In conclusion, these results suggest that in Egypt, HCV along with schistosomal parasite infection is the major risk factor for chronic liver disease. In most Egyptian patients, HCV genotype 4 is highly prevalent.

Biochemical effect of antioxidants on lipids and liver function in experimentally-induced liver damage.

Recent studies demonstrated the role of antioxidants in preventing organ damage caused by free radicals. The present study was conducted to find out the modulatory effect of some antioxidants on lipid patterns in experimentally-induced liver damage. Rats chronically intoxicated with carbon tetrachloride (CCl4) were used as a model of liver injury terminating with fibrosis or cirrhosis. One hundred and sixty six albino rats were classified into five groups: one served as a control group; the second was subjected to oral administration of CCl4 (200 microL/100 g body weight) twice a week; the other three groups, in addition to CCl4, received oral doses of silymarin (30 mg/kg), vitamin E (200 IU/kg) and vitamin C (50 mg/kg) respectively. At the end of the experiment, the animals were killed, blood was collected and liver was taken for histopathological examination. Liver function tests, disturbed by CCl4 were significantly modulated by antioxidants, and histopathological examination showed that antioxidants ameliorated the necrotic and fibrotic changes caused by CCl4. Treatment with antioxidants was also shown to modulate the toxic effect of CCl4 on the lipid profile and malondialdehyde content. Administration of antioxidants could play an important role in prophylaxis against lipid peroxidation and consequently liver fibrosis caused by free radicals.

Transfection of HepG2 cells with infectious hepatitis C virus genome.

Hepatitis C virus (HCV) represents one of the major causes of acute and chronic hepatitis, cirrhosis, and hepatocellular carcinoma (HCC) around the world. Our knowledge of the life cycle of HCV, however, is limited. Current studies are hampered by the lack of a reproducible, high-level in vitro replication system of HCV. We sought to establish HCV replication in HepG2 cells by gene transfer of in vitro transcribed HCV RNA. In preliminary experiments, diethylaminoethyl-dextran led to more efficient gene transfer than cationic liposomes (lipofectin, lipofectamine, and DOTAP). Therefore, in subsequent experiments, HepG2 cells were transfected with full-length (9.6-kb) and near-full-length (9.4-kb) HCV RNA using diethylaminoethyl-dextran. Transfection with subgenomic HCV RNA and mock transfection were used as controls. Positive- and negative-strand HCV RNA sequences were detected by reverse transcription polymerase chain reaction (KT-PCR) for 60 days in the infectious HCV RNA transfected HepG2 cells. The presence of negative-strand HCV RNA, presumably representing replicative intermediates, was confirmed by ribonuclease protection assay. The intracellular levels of HCV RNA were measured by quantitative competitive RT-PCR from 10 to 50 days after transfection and were stable over this time period at moderately high levels (10(8) to 10(10) genomes per mg of total RNA). Expression of viral core and nonstructural proteins was detected in the cytoplasm of transfected cells by immunostaining. Virus-like particles measuring 50 to 60 nm in diameter were found by electron microscopy in cytoplasmic vesicles and conditioned media of the cells transfected with infectious HCV RNA but not in cells transfected with truncated HCV RNA. Culture supernatants of infectious HCV RNA transfected HepG2 cells were infectious for Daudi cells for three passages tested. The truncated HCV RNA lacking NS5 and 3' untranslated region (3' UTR) of HCV was replication incompetent. This is the first demonstration of HCV particles in HepG2 cells after transfection with infectious HCV RNA. We conclude that we have established a reproducible HCV replication system in HepG2 cells that can be used to study the life cycle of HCV and to test anti-HCV agents.

UGP in urogenital disorders: Egyptian experience.

UGP (Urinary gonadotropin peptide) also know as urinary gonadotropin fragment (UGF) or the beta-core of hCG (c beta hCG), was identified as a peptide with a molecular weight of 10.5 kD, having the same amino acid sequence as the core section of the beta-subunit of human chorionic gonadotropin. UGP has been found in normal pregnancy urine as well as in the urine of patients with gestational trophoblastic and non-trophoblastic malignancies. The aim of the present work was to investigate the clinical value of UGP in Egyptian patients with urogenital disorders. The study included 793 cases (462 males and 331 females) classified into 5 groups: 277 with bladder cancer, 121 with benign urinary tract disorders, 27 with different gynecological malignancies, 53 with benign gynecological disease and 315 apparently healthy individuals as a control group. The normal females included 88 premenopausal and 71 postmenopausal women. UGP was determined in 24- hour urine samples from all cases, and in morning urine samples from 151 subjects by ELISA technique using the reagents supplied by Ciba Corning Diagnostics, CA, USA (Triton UGP - EIA). The results of this study revealed significant elevation of UGP in cancer patients when compared to either normal controls or patients with benign diseases. Females in the control and benign diseases groups expressed higher UGP values than males and UGP in postmenopausal women was significantly elevated when compared to premenopausal control females. A a tumor marker, UGP was more sensitive and more specific in bladder than in gynecological cancer. A significant correlation (r = 0.934) was obtained between UGP levels in 24-hr and morning urine samples.

Comparative study between sonography, pathology and UGP in women with perimenopausal bleeding.

Adenocarcinoma is the commonest primary malignancy encountered in the endometrium. Adenomatous hyperplasia represents an important precancerous endometrial lesion. In this study, different techniques have been applied in a trial to early detect endometrial carcinoma and to distinguish between hyperplasia with minimal and high risk of progression to endometrial adenocarcinoma. Eighty women were included in this study and classified into 4 groups: 10 with adenocarcinoma, 28 with simple hyperplasia, 12 with hyperplasia with atypia and 30 normal healthy women. All individuals were subjected to Doppler endovaginal ultrasonography (EVS) for endometrial thickness and uterine artery resistance index (RI). Endometrial biopsy was taken for histopathological examination and DNA analysis. 24-hr urine was collected for the estimation of UGP by ELISA using reagents supplied by Ciba Corning Diagnostica, Alameda, CA, USA (Triton UGP-EIA). On referring to histopathological findings, no single parameter was seen to be specific and sensitive enough to differentiate between benign and malignant endometrial lesions. Doppler endovaginal ultrasonography could detect 76% of endometrial abnormalities. DNA ploidy and UGP showed equal sensitivity rate (60%) in endometrial carcinoma but DNA ploidy was more specific than UGP (0% and 10% false positivity in benign endometrial diseases respectively.

Urinary gonadotropin peptide (UGP) in Egyptian patients with benign and advanced malignant urological disease.

Urinary gonadotropin peptide (UGP) levels were determined in urine samples from 450 Egyptian subjects to determine its relative level of expression in benign and malignant urological disease, and normal individuals. The mean UGP level in patients with bladder cancer was 44-fold higher than in patients with benign disease, and 81-fold higher than in normal individuals. At specificities of 95% and 100%, overall sensitivities of 73% and 60%, respectively, were observed for the detection of malignant disease. Mean UGP levels in patients with bladder cancer were significantly correlated with the stage and grade of malignant disease but did not vary significantly when stratified according to histological type of disease, nodal involvement or bilharzial association. UGP could be a potentially useful marker for the differentiation of benign from malignant urological disease.

Urinary beta-HCG in benign and malignant urinary tract diseases.

Detectable levels of HCG have been reported in conditions other than normal pregnancy, including threatened abortion, ectopic pregnancy, trophoblastic tumors, carcinomas of the stomach, liver, pancreas and breast as well as multiple myeloma and melanoma. The present study was conducted to estimate urinary beta-HCG in bladder cancer and benign urinary tract disorders. 163 individuals were included, 68 with bladder cancer (60 males and 8 females), 64 with benign urinary tract diseases (55 males and 9 females) and 31 normal healthy controls (26 males and 5 females). Urinary beta-HCG was estimated by the ELISA technique using the reagents supplied by DRG International Inc., Germany. Results of the study revealed an overexpression of beta-HCG in malignant and benign urinary tract diseases. 60.3% of the cancer patients and 29.7% of patients with benign diseases showed urinary beta-HCG values above the upper limit of the control group (2mIU/ml).

Serum TPS versus TPA in Egyptian bladder cancer patients.

This study included 328 cases (106 with bladder cancer, 152 with non-malignant urinary tract diseases and 70 healthy controls). Serum TPA was determined using the Prolifigen TPA IRMA kit supplied by AB Sangtec Medical, Bromma, Sweden and serum TPS was determined using the TPS IRMA kit supplied by Beki Diagnostics AB, Bromma, Sweden. The results of this study revealed that serum TPA had better sensitivity than serum TPS while no marked difference was found in the false-positivity rates in the non-malignant urinary tract diseases. A correlation coefficient of 0.83 was found between serum TPA and TPS. No relation was found between either TPA or TPS and histopathological stage, grade or association of the tumor with bilharziasis. As regards the histopathological type of the tumor, serum TPS was slightly higher in squamous cell than transitional cell carcinoma but TPA showed no difference. In the follow-up of bladder cancer patients after surgery both TPA and TPS showed an excellent concordance with the clinical state of the patients. In conclusion, TPS does not seem to be an optimal test in Egyptian patients with bladder cancer but serial determinations of one of the two markers can be used in the follow-up of these patients after surgery.

Luminoimmunometric assay of tissue polypeptide antigen (TPA) and cancer antigen 125 (CA-125) in breast cancer patients.

Serum TPA and CA-125 were determined in 86 individuals (66 with breast cancer representing the different stages and grades of the disease and 20 normal healthy controls). TPA and CA-125 were estimated using the LIA reagents supplied by BYK Sangtec. TPA showed sensitivity rates of 31.8%, 42.4% and 51.5% while CA-125 showed sensitivities of 16.3%, 18.6% and 25.6% at specificity levels of 100%, 95% and 90% respectively. Combined determination of the two markers resulted in some improvement in sensitivity. For follow-up of breast cancer patients after surgery both markers were of value and showed near-identical patterns.

Simultaneous determination of urinary CEA, ferritin and TPA in Egyptian bladder cancer patients.

Urinary carcinoembryonic antigen (CEA), ferritin (Fer) and tissue polypeptide antigen (TPA) were determined in 328 cases (106 with bladder cancer, 152 with non-malignant urinary tract disease and 70 healthy controls). CEA was determined by the kit supplied by Roche Diagnostica (CEA EIA Doumab 60), ferritin by the Tandem-E Fer kit supplied by Hybritech and TPA by the Prolifigen TPA-IRMA kit supplied by Sangtec Medical. The results of this work revealed that combined determination of urine CEA and Fer, CEA and TPA or Fer and TPA showed higher sensitivity than determination of the individual markers. There was no significant difference between combined and individual marker determination with respect to false positivity in non-malignant urinary tract diseases. At 97% specificity, the sensitivities of urine CEA, Fer and TPA were 82.1%, 71.7% and 90.6%, respectively, while combined urine CEA & Fer, CEA & TPA and Fer & TPA showed sensitivities of 92.5%, 99.1% and 98.1%, respectively. When the specificity was related to the entire non-cancer group (patients with benign urinary tract diseases and normal controls), some reduction in the sensitivities of the combined markers was noted compared to the normal group only. In conclusion, combined determination of urine markers is superior to determination of individual markers in the diagnosis of bladder cancer.