Increased proto-oncogene expression in peripheral blood lymphocytes from patients with systemic lupus erythematosus and other autoimmune diseases

Clinical and laboratory observation systemic lupus erythematosus and acute lymphocytic leukemia: An unusual case

The association of systemic lupus erythematosus (SLE) and myeloproliferative and lymphoproliferative malignancies is widely reported. There is scarce information available with regards to the association of SLE and malignancy in children. Usually, SLE precedes the onset of lymphoproliferative disease, but the neoplasia can occur earlier or even simultaneously. There are only five pediatric cases of SLE and associated acute lymphoblastic leukemia (ALL) reported in literature. All of these except one satisfied the revised American College of Rheumatology Criteria for SLE. Three of these cases developed SLE several years after successful treatment of ALL. While two cases reported had simultaneous onset of SLE and ALL, one of the cases in this two-patient series, did not fulfill ≥4 criteria for diagnosis of SLE. We present a case of a 3-year-old boy with SLE and coexistent ALL. To the best of our knowledge, only two such cases of simultaneous presentation of both these diseases are present in literature.

Hematological features of pediatric systemic lupus erythematosus: suggesting management strategies in children

Aim: The aim of this study was to analyze the hematological features in children with systemic lupus erythematosus (SLE) and to review our current treatment protocols. Methods: We evaluated hematological findings of 43 children with SLE diagnosed and followed at the Pediatric Rheumatology Division of Hacettepe University, Turkey. Thirty-seven patients with hematological abnormalities were analyzed in detail. Results: Median age at presentation was 13 years. Hematological involvement was seen in 86% of patients. The most common hematological finding was anemia ( n = 30). Anemia was either a Coombs (+) hemolytic one, or was due to other causes. Hemolytic anemia was treated with steroids and intravenous gamma globulin (IVIG). Leucopenia and thrombocytopenia were detected in 35.1 % and 37.8 %, respectively. Bone marrow aspiration was performed in 15, mainly for cytopenia. Secondary dysplastic changes were common. Acute lymphoblastic leukemia (ALL) was diagnosed in one patient. Six patients were diagnosed as having macrophage activation syndrome (MAS). One patient died due to secondary infections and multiorgan failure despite aggressive treatment. In patients diagnosed early, treatment with steroids and cyclosporine resulted in an excellent response. Thrombotic microangiopathy was detected in two patients. Both were treated successfully with steroids and plasma exchange. Antiphospholipid and anticardiolipin antibodies were positive in 12 and 15 of the patients, respectively. Five developed deep vein thrombosis (DVT), one cerebral sinus thrombosis and one presented with purpura fulminans. They were effectively treated with anticoagulation protocol. Conclusion: Hematological findings should be carefully assessed and treated vigorously to prevent the morbidity and possible mortality.

Variants within MECP2, a key transcription regulator, are associated with increased susceptibility to lupus and differential gene expression in patients with systemic lupus erythematosus

OBJECTIVE

Both genetic and epigenetic factors play an important role in the pathogenesis of lupus. The aim of this study was to examine methyl-CpG-binding protein 2 gene (MECP2) polymorphisms in a large cohort of patients with lupus and control subjects, and to determine the functional consequences of the lupus-associated MECP2 haplotype.

METHODS

We genotyped 18 single-nucleotide polymorphisms within MECP2, located on chromosome Xq28, in a large cohort of patients with lupus and control subjects of European descent. We studied the functional effects of the lupus-associated MECP2 haplotype by determining gene expression profiles in B cell lines in female lupus patients with and those without the lupus-associated MECP2 risk haplotype.

RESULTS

We confirmed, replicated, and extended the genetic association between lupus and genetic markers within MECP2 in a large independent cohort of lupus patients and control subjects of European descent (odds ratio 1.35, P = 6.65 x 10(-11)). MECP2 is a dichotomous transcription regulator that either activates or represses gene expression. We identified 128 genes that are differentially expressed in lupus patients with the disease-associated MECP2 haplotype; most ( approximately 81%) were up-regulated. Genes that were up-regulated had significantly more CpG islands in their promoter regions compared with genes that were down-regulated. Gene ontology analysis using the differentially expressed genes revealed significant association with epigenetic regulatory mechanisms, suggesting that these genes are targets for MECP2 regulation in B cells. Furthermore, at least 13 of the 104 up-regulated genes are regulated by interferon. The disease-risk MECP2 haplotype was associated with increased expression of the MECP2 transcription coactivator CREB1 and decreased expression of the corepressor histone deacetylase 1.

CONCLUSION

Polymorphism in the MECP2 locus is associated with lupus and, at least in part, contributes to the interferon signature observed in lupus patients.

Altered T and B lymphocyte signaling pathways in lupus

Systemic lupus erythematosus (SLE) has long been recognized to be characterized by dysregulated signaling pathways in T and B lymphocytes, beginning with observations of cellular hyperactivity and hyperresponsiveness, and evolving to recent studies focused upon the genetic and molecular bases of such phenomena. This review focuses on recently elucidated signaling abnormalities currently thought to be intrinsic to T and/or B cells in human SLE.

Naive CD4+ T Cells from Lupus-Prone Fas-Intact MRL Mice Display TCR-Mediated Hyperproliferation Due to Intrinsic Threshold Defects in Activation

Autoreactive T cell activation is a consistent feature of murine lupus; however, the mechanism of such activation remains unclear. We hypothesized that naive CD4+ T cells in lupus have a lower threshold of activation through their TCR-CD3 complex that renders them more susceptible to stimulation with self-Ags. To test this hypothesis, we compared proliferation, IL-2 production, and single cell calcium signaling of naive CD4+ T cells isolated from Fas-intact MRL/+(Fas-lpr) mice with H-2k-matched B10.BR and CBA/CaJ controls, following anti-CD3 stimulation in the presence or absence of anti-CD28. We also assessed the responsiveness of naive CD4+ T cells isolated from Fas-intact MRL and control mice bearing a rearranged TCR specific for amino acids 88-104 of pigeon cytochrome c to cognate and low affinity peptide Ags presented by bone marrow-matured dendritic cells. TCR transgenic and wild-type CD4+ T cells from MRL mice displayed a lower threshold of activation than control cells, a response that was class II MHC dependent. The rise in intracellular calcium in MRL vs controls was enhanced and prolonged following anti-CD3 triggering, suggestive of proximal defects in TCR-engendered signaling as the mechanism for the observed hyperactivity. These findings were observed as early as 1-2 mo postweaning and, based on analysis of F1 T cells, appeared to be dominantly expressed. This genetically altered threshold for activation of MRL T cells, a consequence of a proximal defect in CD3-mediated signal transduction, may contribute to the abrogation of T cell tolerance to self-Ags in lupus.

Activated peripheral blood mononuclear cells detected in lupus patients using cDNA coding for proliferating cell nuclear antigen

Abstract The expression of proliferating cell nuclear antigen (PCNA) mRNA in peripheral blood mononuclear cells (PBMCs) from patients with systemic lupus erythematosus (SLE) was measured by dot blot hybridization using a PCNA cDNA, and correlated with the percentage of PCNA-positive cells detected immunohistochemically using a monoclonal anti-PCNA antibody. PCNA-positive PBMCs were detected in 72.2% of SLE patients (n = 36), which is significantly more than among healthy controls. In addition, among those in whom PCNA expression was detected, the percentage of PBMCs expressing PCNA was significantly higher in SLE patients (mean 2.5% vs. 0.15%). The level of PCNA mRNA was increased in PBMCs from 83.3% of SLE patients, and was significantly correlated with the percentage of PCNA-positive cells (r = 0.54, P < 0.01) and with the disease activity score (r = 0.56, P < 0.01). A longitudinal study of two SLE patients confirmed that PCNA mRNA expression and the percentages of PCNA-positive cells varied in parallel with disease activity. Thus, an analysis of activated PBMCs from SLE patients using PCNA cDNA may be a useful method by which to estimate SLE disease activity.

Is cancer an autoimmune process dependent on anti-apoptotic autoantibodies?

Dysregulated apoptosis is a potentially important mechanism in the pathogenesis of cancer. Autoantibodies, which inhibit apoptosis, have recently been identified in patients with malignant diseases. We suggest that such inhibitory autoantibodies participate in tumorigenesis. These views may provide a basis for the increased incidence of cancer in patients with autoimmune diseases and have novel therapeutic implications for cancer.

Lymphocyte apoptosis and apoptosis-associated gene expression in Sjögren's syndrome

OBJECTIVE

To study the mechanism and regulation of apoptosis in peripheral blood T and B lymphocytes from patients with Sjögren's syndrome (SS).

METHODS

The mode of in vitro lymphocyte death in the peripheral blood of patients with SS was determined by fluorescence microscopic analysis, terminal deoxynucleotidyl transferase assay, and DNA fragmentation analysis. Apoptotic cell death of T and B cells was determined at 48 hours of culture by fluorescence-activated cell sorter analysis of propidium iodidestained cells. Messenger RNA (mRNA) expression of bcl-2, bcl-x, bax, and c-myc in T and B cells was determined by enzyme-linked immunosorbent assay-polymerase chain reaction (ELISA-PCR). Expression of bcl-xL and bcl-xS was determined by Southern blot analysis of PCR products. Gene expression was calculated as the ratio of each gene message to the message of the GAPDH gene. Bcl-2 protein levels in SS T cells were determined by ELISA.

RESULTS

SS T cells showed increased in vitro apoptosis compared with normal T cells (mean +/- SD 12.3 +/- 4.5% versus 7.3 +/- 2.0%; P < 0.01). Freshly isolated SS T cells showed increased expression of bcl-2 mRNA compared with normal controls (mean +/- SD 1.50 +/- 0.65 versus 0.88 +/- 0.23; P < 0.05). There was no significant difference in levels of bax or c-myc mRNA in T cells and B cells between SS patients and normal controls. When SS T lymphocytes were cultured in vitro for 72 hours, Bcl-2 protein levels decreased with time.

CONCLUSION

SS T cells showed accelerated apoptosis in vitro. Freshly isolated SS T cells had increased expression of bcl-2. An increase in death-promoter signals and decrease in death-suppressor signals in vitro may have been responsible, in part, for the apoptosis in SS T lymphocytes.

Reactive oxygen species, chromosome mutation, and cancer: possible role of clastogenic factors in carcinogenesis

Superoxide radicals may induce genotoxic effects by indirect action mechanisms, implicating the formation of more long-lived, secondary clastogenic material called chromosome breakage factors or clastogenic factors (CF). CF are produced via the intermediacy of superoxide, and stimulate further superoxide production by competent cells. This results in a selfsustaining and longlasting process of clastogenesis, which may exceed the DNA repair system and ultimately lead to cancer. An increased cancer risk is indeed observed in conditions accompanied by CF formation. These include irradiated persons, asbestos workers, patients with chronic inflammatory diseases, HIV-infected persons, and the congenital breakage syndromes ataxia telangiectasia, Bloom's syndrome, and Fanconi's anemia. Because reactive oxygen species (ROS) are implicated in CF formation and CF action, antioxidants may be protective as anticlastogens and consequently as anticarcinogens. In persons at high risk because of their occupation, life style or place of residence, the presence of CF may represent an indication for chemoprevention of cancer by antioxidants. CF can be useful as biochemical markers and intermediate endpoints for the evaluation of promising drugs. They are therefore not only of interest as a mechanism by which ROS may exert genotoxic effects, but also have practical implications.

Bcl-2 and Fas, molecules which influence apoptosis. A possible role in systemic lupus erythematosus?

Polyclonal B cell activation and the production of antibodies against a variety of autoantigens are features of systemic lupus erythematosus (SLE). Autoreactive B cells are found in healthy individuals but their numbers are probably regulated by cell death, after a few days, in the absence of proliferative stimuli. The process which achieves this regulation is known as apoptosis or programmed cell death. It has been postulated that in SLE patients dysfunction of apoptosis could result in the inappropriate longevity of autoreactive B cells, allowing autoantibody levels to reach pathogenic thresholds. This hypothesis has arisen as a result of studies revealing links between autoimmunity and two molecules which influence apoptosis. These are bcl-2 which enhances cell survival by inhibiting or delaying apoptosis and Fas, a cell surface molecule involved in the induction of apoptosis. Transgenic mice over expressing bcl-2 in their B cells showed polyclonal B cell expansion and their B cells showed extended survival in vitro. After a few months these mice developed an autoimmune syndrome resembling SLE. Mice that carry the lpr disorder have defects in the Fas gene. These mice, which do not express functional Fas molecules, suffer from an SLE-like autoimmune syndrome. Thus inappropriate expression of both bcl-2 and Fas can result in SLE-like autoimmune disease in mice. Research is now in progress to ascertain whether quantitative or functional abnormalities in these molecules exist in human SLE patients and contribute to the pathogenesis of the disease in some or all cases.

Expression of c-myc, c-myb, and c-sis in fibroblasts from affected and unaffected skin of patients with systemic sclerosis

We examined c-sis, c-myc, and c-myb proto-oncogene expression in fibroblasts cultured from affected and unaffected skin of patients with systemic sclerosis (SSc), and from healthy donor skin. Total cellular RNA from cultured dermal fibroblasts was used in slot blot analysis and scanning densitometry or phosphorimaging to quantify steady-state levels of proto-oncogene mRNAs. PDGF B-chain levels in culture supernatants of fibroblasts were determined by ELISA. Our results demonstrate that steady-state levels of c-myc and c-myb mRNA were elevated 1.5- to 5.6-fold in intralesional fibroblasts from SSc patients as compared to other cells examined. Levels of c-sis mRNA and PDGF-B protein were comparable regardless of source. Elevated c-myc and c-myb expression may be indicative of, and may contribute to, fibroblast activation in SSc.

Immune-mediated disease as a risk factor for canine lymphoma

BACKGROUND

Autoimmune diseases and neoplasia have been associated as occurring simultaneously in individuals. This study evaluated the association between the simultaneous occurrence of canine lymphoma and various immune-mediated diseases.

METHODS

The Veterinary Medical Data Program, a national disease data registry for veterinary schools, was examined. The following immune-mediated disease categories were evaluated: lupus disorders, pemphigus disorders, autoimmune polyarthritis, immune-mediated hemolytic anemia, and immune-mediated thrombocytopenia. Odds ratios with 99% confidence intervals were calculated for the occurrence of lymphoma and each of the immune-mediated disorder categories.

RESULTS

Only dogs with immune-mediated thrombocytopenia had a statistically significantly increased odds ratio (5.61; 99% confidence interval, 4.16-7.57) for the occurrence of lymphoma versus the general population. This association still was observed for immune-mediated thrombocytopenia when stratified by age, sex, and neutering status.

CONCLUSION

Dogs with immune-mediated thrombocytopenia had a greater occurrence of lymphoma than dogs without immune-mediated thrombocytopenia.

Increased risk of cancer in patients with systemic lupus erythematosus

To evaluate the risk of cancer in patients with systemic lupus erythematosus (SLE) a series of 205 consecutive patients (182 women and 23 men) were followed up for cancer through the files of the Finnish Cancer Registry. The follow up consisted of a total of 2340 person years. Fifteen cancers were diagnosed against 5.7 expected (relative risk (RR) 2.6, 95% confidence interval (CI) 1.5 to 4.4). Among the women there were four non-Hodgkin's lymphomas against 0.09 expected (RR 44, CI 11.9 to 111) and two soft tissue sarcomas against 0.04 expected (RR 49, CI 6.0 to 177). When evaluated by a case control study previous treatment with cytostatic drugs showed no influence on the occurrence of cancer in this series of patients with SLE.

Autoantibodies to c-myc protein: elevated levels in patients with African Burkitt's lymphoma and normal Ghanians

Sera from U.S. patients with SLE, RA, and various malignancies, clinically normal individuals with sero-activity to HIV, AIDS, and from pregnant women were tested for the presence of anti-c-myc antibodies. In an ELISA using recombinant human c-myc protein as the antigen, no difference in mean antibody titer was generally detected in these sera when compared to normal controls. Only three malignancy sera (two myeloid leukemia and only one lymphoma) and two patients with AIDS-related lymphoma exhibited exceedingly higher levels of anti-c-myc antibody. However, significantly elevated anti-c-myc antibody levels were found among 20 patients with African Burkitt's lymphoma (Ghana) and 20 normal Ghanians, thus apparently reflecting an autoimmune phenomenon prevalent in the endemic region. These findings indicated that elevated levels of anti-c-myc antibodies are not a general characteristic of patients with diseases that have been associated with increased expression of c-myc.

Protooncogene (C-Myc) expression in the infiltrating cells of lesional skin from patients with systemic lupus erythematosus

Polyclonal activation of lymphocytes due to an unknown cause is considered to be one of the most important findings of systemic autoimmune disorders including systemic lupus erythematosus (SLE). In order to confirm the expression of the C-Myc protooncogene in lesional skin, tissue specimens from SLE were examined by the histo in situ hybridization method and a histochemical method using a specific antibody reactive with C-Myc related products. Twenty-two cases of SLE, six cases of DLE, one case of lupus erythematosus profundus, two cases of lichen planus, and five skin specimens from healthy volunteers were selected for the examination. In the SLE group, further comparative examination of diseased skin and normal skin from the same patient, and of diseased skin in an active stage and a stable stage in the same SLE patient with renal involvement, were carried out. In most of the active SLE cases, protooncogene expression had apparently increased as compared with the expression in the groups of inactive and treated SLE, active DLE, active lichen planus, and those with healthy skin. Even in normal-appearing skin from active SLE without other organic failure, the protooncogenes were not expressed very strongly.

Differential expression of Raf-1 protooncogene in resting and activated human leukocyte populations

In this study we examined by Northern blot analysis the expression of Raf-1 protooncogene in normal human peripheral blood leukocytes. Unlike thymocytes, circulating lymphocytes did not express appreciable levels of Raf-1 mRNA. In contrast, polymorphonuclear cells (PMN) had high levels of Raf-1 transcripts. Also density gradient separated monocytes showed Raf-1 mRNA but at lower levels compared to PMN. Expression of Raf-1 was constitutive inasmuch as it was not induced by the purification procedure. The half-life of Raf-1 mRNA in PMN was greater than 4 h. Functional activation of PMN and monocytes with various stimuli (phorbol esters, tumor necrosis factor, colony stimulating factors, LPS) did not affect Raf-1 expression. By contrast, density gradient purified monocytes allowed to adhere to plastic for 1 h expressed augmented levels of Raf-1. Monocytes cultivated in suspension or allowed to adhere to plastic showed an half-life of Raf-1 transcripts of, respectively, more than 4 h and less than 30 min. Circulating lymphocytes stimulated with mitogens (PHA, conA, anti-CD3 antibodies, and Staphylococcus aureus) also expressed high levels of transcripts of this protooncogene. PHA-induced transcripts in lymphocytes had an half-life greater than 4 h. The pattern of expression of Raf-1 in resting and activated leukocytes suggests that this protooncogene may play a role in expression of differentiated functions and activation of these cells.

5-Methylcytosine content of DNA in blood, synovial mononuclear cells and synovial tissue from patients affected by autoimmune rheumatic diseases

The percentage of 5-methylcytosine (m5Cyt) has been determined in peripheral blood, synovial mononuclear cells and synovial tissue from patients affected by various rheumatic autoimmune diseases. The determination was performed by reversed-phase high-performance liquid chromatography. Fifteen controls were compared to twenty-one patients affected by rheumatoid arthritis and to nine patients affected by systemic lupus erythematosus. The mean percentage of m5Cyt in normal individuals was significantly higher than in the rheumatoid arthritis and systemic lupus erythematosus patients. In addition, patients with active disease showed lower values than patients in remission. This finding is in agreement with the hypothesis that DNA hypomethylation may play a role in the pathogenesis of the autoimmune diseases, resulting in altered oncogene expression. Therapy with cyclosporin A led to a decrease in the percentage of m5Cyt in three rheumatoid arthritis patients, but a rebound was observed when the cyclosporin A was suspended. The percentage of m5Cyt in the DNA of synovial tissue from four rheumatoid arthritis patients and five patients with osteoarthritis was similar; this observation confirms that, in addition to disease-specific and disease activity-specific variations, the percentage of m5Cyt may also show tissue-specific variations.

Proto-oncogene expression in peripheral blood mononuclear cells in IgA nephropathy

We have investigated the expression of proto-oncogenes in mononuclear cells obtained from patients with IgA nephropathy using a RNA hybridization technique. Patients with IgA nephropathy expressed more c-myc, c-raf, c-fos, and c-jun proto-oncogene RNA than did normal controls. However, no significant expression of c-N-ras, c-mos or c-myb genes was found in the mononuclear cells of these patients. When the amount of urinary protein excretion was used as an indicator of disease activity (greater than 1 g/day), a positive correlation was found between c-myc, c-raf, c-fos, and c-jun expression and urinary protein excretion (P less than 0.01). The expression of these genes correlated also with the serum IgA concentration (P less than 0.01), IgA immune complex (P less than 0.01), and histopathological changes in renal tissues obtained from patients with IgA nephropathy (P less than 0.01). The results of this survey suggest that abnormally regulated proto-oncogene expression in mononuclear cells may play an important role in the progression of IgA nephropathy and may be useful as an indicator of disease activity and/or prognosis.

Expression of the collagenolytic and Ras-induced cysteine proteinase cathepsin L and proliferation-associated oncogenes in synovial cells of MRL/I mice and patients with rheumatoid arthritis

Based on the observation that rheumatoid joint destruction is related to the presence of transformed-appearing proliferating synovial lining cells attached to cartilage and bone at the site of early destruction, we searched for the expression of proliferation- and transformation-associated oncoproteins in synovial tissues from patients with early destructive rheumatoid arthritis (RA). Immunolocalization of Ras and Myc proteins was found in about 70% of the RA cases and was restricted to the proliferating synovial lining cells. The cysteine proteinase, cathepsin L, which has been shown to be the major ras-induced protein in ras-transformed murine NIH 3T3 cells, was detected in 50% of the RA cases, predominantly in synovial cells attached to cartilage and bone at the site of joint destruction. Moreover, utilizing cytoplastic dot hybridization analysis, we demonstrated the presence of RNA sequences complementary to human cathepsin L in primary cultures of human synovial cells from RA joints and complementary to murine cathepsin L in synovial lining cells derived from MRL/l mice developing spontaneously a RA-like disease. Significant levels of ras oncogene transcripts and products in human RA synovial cells associated with an increased expression of the cathepsin L gene indicate that this collagen-degrading enzyme may contribute to the destruction of cartilage and bone in RA.

Activated peripheral blood mononuclear cells detected by murine monoclonal antibodies to proliferating cell nuclear antigen in active lupus patients

Hybridoma producing monoclonal antibody to proliferating cell nuclear antigen (PCNA/cyclin) (TOB7, IgG1 kappa) was newly established. Using TOB7, PCNA was detected in the peripheral blood mononuclear cells (PBMC) in patients with systemic lupus erythematosus (SLE). Forty-four of 58 patients with SLE had PBMC expressing PCNA. The percentage of PCNA-positive PBMC in patients with SLE was 0-20% (mean: 2.63%) which was significantly higher (P less than 0.01) compared with normal controls (mean: 0.18%), patients with rheumatoid arthritis (mean: 0.83%), and patients with mixed connective tissue disease (mean: 0.38%). Patients with high numbers of PCNA positive PBMC tended to complicate pulmonary disorders (P less than 0.005), especially pulmonary fibrosis (P less than 0.005). In addition, the percentage of PCNA-positive cells in SLE patients correlated with the disease activity (r = 0.45, P less than 0.01). The lymphocyte subsets of PCNA-positive PBMC were examined, and most of those cells belonged to CD4- or CD8-positive T-cell populations in three lupus patients. Our findings indicate that PCNA-positive activated PBMC are present in SLE patients and the percentage of PCNA-positive PBMC may be used as an indicator of disease activity.

c-myc proto-oncogene expression in peripheral blood mononuclear cells from patients with primary Sjögren's syndrome

We examined peripheral blood mononuclear cells (PBMC) from 16 patients with Sjögren's syndrome (SS) and 7 normal control subjects for the expression of the c-myc proto-oncogene. Patients with SS were found to have a significantly increased expression of c-myc messenger RNA compared with normal individuals. No abnormal forms of c-myc RNA were detected in the SS patients. DNA analysis did not show deletion, rearrangement, or amplification in the c-myc proto-oncogene. The methylation status of the c-myc gene in patients with SS was found to be comparable with that of the control subjects. Nuclear run-off assays showed increased transcription of the c-myc gene in some patients but normal transcription in others, suggesting that posttranscriptional mechanisms are also involved in the increased c-myc messenger RNA observed in these patients. Two patients with primary SS and B cell lymphomas were found to have normal c-myc expression in their PBMC. These results demonstrate the presence of activated PBMC in patients with primary SS and delineate some of the mechanisms that are involved at the molecular level. We speculate that increased c-myc expression may represent an early permissive event in the progression toward neoplasia in these patients.

Transcriptional and post-transcriptional mechanisms are responsible for the increased expression of c-myc protooncogene in lymphocytes from patients with systemic lupus erythematosus

Peripheral blood mononuclear cells (MNC) of patients with systemic lupus erythematosus (SLE) have increased expression of the c-myc protooncogene. The factors which are responsible for the accumulation of c-myc mRNA levels in SLE MNC, however, have not been determined. We have investigated the steady-state mRNA accumulation, nuclear transcription rate, rate of mRNA degradation as well as methylation status for the c-myc protooncogene in patients with SLE. Increased transcription rate of c-myc protooncogene and slow degradation rate of c-myc mRNA both appear to contribute to the accumulation of c-myc RNA in peripheral blood MNC of patients with SLE. Site-specific methylation of the human c-myc protooncogene in patients with SLE does not differ from that of normal controls. These findings provide evidence for both transcriptional and post-transcriptional alterations of c-myc protooncogene expression in human SLE.

Rheumatoid factor and Fc signaling: a tale of two Cinderellas

Signaling to lymphocytes depends not only upon the interaction of receptors with specific antigen, but also upon antigen nonspecific receptors which receive input from two classes of molecules, immunologically specific end products and lymphokines. These represent the central elements in the physiologic stimulation of immune responses to both self and foreign antigens. This review is dedicated primarily to describing the function of physiologically active receptors for end product which are central to end product feedback in normal immune responses. The emergence of autoimmunity as a pathologic process resultant from a defective end product signaling mechanism is described.

Detection of antibodies to the antigens involving differentiation of myeloid cells in sera from patients with systemic lupus erythematosus

The sera from 66 patients with systemic lupus erythematosus (SLE) were examined by the immunoblotting method to detect antibodies to the antigens on the cultured myeloid cell lines, fresh monocytes and granulocytes, and were compared with the sera from 26 healthy subjects sex- and roughly age-matched to the patients. The sera from SLE patients demonstrated antibodies to many antigens on myeloid cells at high frequencies, compared with healthy subjects. A high reactivity with similar patterns was demonstrated with K562, KG-1 and HL60 cells, while reactivity to U937, monocytes and granulocytes was rather low. In particular, the sera from SLE patients were found to contain the antibody to the antigens with Mr of 60K on K562, KG-1, and HL60 cells, which are known to express a good amount of c-myc products. However, the sera from healthy subjects demonstrated hardly any antibody to the 60K antigen on HL60 cells. After an incubation of HL60 cells with TPA or vitamin D3 to induce their monocytic differentiation, the SLE sera became able to detect the 55K antigen on the differentiated HL60 cells, while the 60K antigen turned to undetectable or only faintly detected. These findings suggested that the 60K antigen on HL60 cells may be related to a gene product involving cell growth or differentiation, such as c-myc protein. Actually, polyclonal antibody to myc-specific peptide could identify the 60K antigen as one of the cellular products of HL60.(ABSTRACT TRUNCATED AT 250 WORDS)

Increased proto-oncogene expression in peripheral blood T lymphocytes from patients with systemic sclerosis

The expression of c-myc, c-myb, and c-ras proto-oncogenes, determined using RNA hybridization techniques (slot-blot), was significantly increased in peripheral blood T lymphocytes, but not in B cells, from 17 patients with systemic sclerosis with diffuse scleroderma, compared with the expression in normal control subjects. The magnitude of expression of c-myc and c-myb tended to be higher in patients with early, active disease. These results demonstrate an in vivo activation of T cells from systemic sclerosis patients, which may play an important role in the pathogenesis of the disease.

Expression of c-raf-1 and A-raf-1 during regeneration of rat liver following surgical partial hepatectomy

The major objective of this study was to investigate the expression of members of the raf family of proto-oncogenes during rat liver regeneration. The steady-state level of expression of both c-raf-1 and A-raf-1 increased three- to fivefold 18-24 h following partial hepatectomy, and it returned to basal levels by 72 h. Expression of c-myc and Ha-ras mRNA was increased at 3 and 18-24 h, respectively, confirming previous reports. Increased steady-state levels of c-raf-1, A-raf-1, and Ha-ras mRNA were also detected in hepatocytes isolated from rat liver 24 h after partial hepatectomy. Thus, elevated expression of the raf genes closely correlated with that of Ha-ras, beginning at 12 h and reaching maximal levels during the first peak of DNA synthesis following partial hepatectomy.

Age-related changes of proliferative response, kinetics of expression of protooncogenes after the mitogenic stimulation and methylation level of the protooncogene in purified human lymphocyte subsets

Proliferative responses of highly purified T and B cells from aged persons to the combined stimulation with ionomycin and PMA were more significantly reduced than that from young ones although the degree of the age-related reduction was more significant in T cells than in B cells. In B cells, the levels and kinetics of c-myc gene expression after the stimulation were comparable between aged and young groups. In T cells, the maximum level of c-myc gene expression after the stimulation was comparable between the two age groups but the rate of reduction of c-myc mRNA was significantly retarded in the aged. The results of nuclear run on transcription assay showed the reduction of the rate of c-myc mRNA degradation seemed to be the cause. The levels and kinetics of c-myb gene expression in either T or B cells were comparable between the two age groups. We further examined the level of methylation of Xho I site of c-myc gene. The level of the methylation was significantly lower in the aged T cells and more significant in aged CD 8 positive T cells although that in aged B cells was comparable to that in young ones. The relation between a reduced proliferation, a retarded rate of c-myc mRNA degradation and reduction of methylation level of c-myc gene was discussed.

Protooncogene expression in peripheral blood mononuclear cells from patients with systemic lupus erythematosus as an indicator of the disease activity

In the present study, we examined the various protooncogene expressions in PBMC (peripheral blood mononuclear cell) of systemic lupus erythematosus (SLE) patients to determine if they could be an indicator for the disease activity. We divided SLE patients into "very active," "active," and "remitting" states according to the clinical symptoms in addition to the laboratory data peculiar to SLE. In addition, we determined the amount of circulating immune complex (IC) as one of the representative laboratory indicators for the disease activity. We found a positive correlation with either c-myc or c-myb expression and the amounts of IC and clinical disease activity. The degree of c-myc and c-myb expression was significantly reduced along with or prior to the amelioration of clinical symptoms and improvement as determined by laboratory data under treatment with prednisolone and/or azathioprine administration. The degree of c-myc and c-myb gene expression had no direct relation to the presence of particular clinical sign(s) or autoantibody. The expression of the c-raf gene was found in SLE and other systemic autoallergic patients although it showed no correlation with the disease activity. No significant expression of c-src, c-ras, c-fos, c-fgr, c-fps, c-fes, c-fms, c-yes, c-rel, c-abl, c-mos, c-sis, and c-erb B genes was found in the patients. c-myc and c-myb expression as having pathogenic and clinical significance is discussed.

Drosophila melanogaster homologs of the raf oncogene

A murine v-raf probe, representing the kinase domain, was used to identify two unique loci in Drosophila melanogaster DNA. The most closely related to v-raf was mapped by in situ hybridization to position 2F5-6 (Draf-1) on the X chromosome, whereas the other raf-related gene (Draf-2) was found at position 43A2-5 on chromosome 2. The nucleotide and amino acid homologies of Draf-1 to the kinase domain of v-raf are 61 and 65%, respectively. The large amount of a 3.2-kilobase Draf-1 transcript detected in eggs as a maternal message decreases during embryonic development, and significant steady-state levels are observed throughout the remainder of morphogenesis. We speculate that the Draf-1 locus plays an important role in early embryogenesis.

Drosophila melanogaster homologs of the raf oncogene

A murine v-raf probe, representing the kinase domain, was used to identify two unique loci in Drosophila melanogaster DNA. The most closely related to v-raf was mapped by in situ hybridization to position 2F5-6 (Draf-1) on the X chromosome, whereas the other raf-related gene (Draf-2) was found at position 43A2-5 on chromosome 2. The nucleotide and amino acid homologies of Draf-1 to the kinase domain of v-raf are 61 and 65%, respectively. The large amount of a 3.2-kilobase Draf-1 transcript detected in eggs as a maternal message decreases during embryonic development, and significant steady-state levels are observed throughout the remainder of morphogenesis. We speculate that the Draf-1 locus plays an important role in early embryogenesis.

Effect of cyclophosphamide therapy on oncogene expression in angioimmunoblastic lymphadenopathy

The expression of four cellular oncogenes was studied by means of northern blot analysis of messenger RNA in peripheral-blood mononuclear cells from patients with angioimmunoblastic lymphadenopathy (AILD). On average, cells from patients with AILD and from those with systemic lupus erythematosus (SLE) expressed significantly more N-ras and significantly less c-fos mRNA than did cells from healthy controls. Expression of these cellular oncogenes was most abnormal in patients with the most severe disease. In contrast, increased levels of c-myc mRNA were found in patients with SLE but not in those with AILD. Administration of cyclophosphamide to patients with AILD was followed by return to normal of both N-ras and c-fos expression.

Pks, a raf-related sequence in humans

A human fetal liver cDNA library was screened at reduced hybridization stringency for v-raf-related sequences. In addition to the expected c-raf-1 cDNA, a second sequence was isolated. Comparison of the second gene (pks) to the other raf-related sequences revealed nucleotide homologies of 71%. The predicted amino acid sequence of the kinase domain is sufficiently similar to that of v-raf to suggest that pks may encode a polypeptide that exhibits serine/threonine kinase activity. The expression of pks mRNA (2.7 kilobases long) is elevated in peripheral blood mononuclear cells isolated from two patients with angioimmunoblastic lymphadenopathy with dysproteinemia, a disease in which autoantibodies are produced following the lymphoproliferative activation of B cells. Analysis of somatic cell hybrids for segregation of the pks locus revealed the presence of an additional locus closely related to the pks sequence.