Identification of pharmacodynamic biomarkers and common molecular mechanisms of response to genotoxic agents in cancer cell lines

PURPOSE

Genotoxic agents (GAs) including cisplatin, doxorubicin, gemcitabine, and topotecan are often used in cancer treatment. However, the response to GAs is variable among patients and predictive biomarkers are inadequate to select patients for treatment. Accurate and rapid pharmacodynamics measures of response can, thus, be useful for monitoring therapy and improve clinical outcomes.

METHODS

This study focuses on integrating a database of genome-wide response to treatment (The NCI Transcriptional Pharmacodynamics Workbench) with a database of baseline gene expression (GSE32474) for the NCI-60 cell lines to identify mechanisms of response and pharmacodynamic (PD) biomarkers.

RESULTS AND CONCLUSIONS

Our analysis suggests that GA-induced endoplasmic reticulum (ER) stress may signal for GA-induced cell death. Reducing the uptake of GA, activating DNA repair, and blocking ER-stress induction cooperate to prevent GA-induced cell death in the GA-resistant cells. ATF3, DDIT3, CARS, and PPP1R15A appear as possible candidate PD biomarkers for monitoring the progress of GA treatment. Further validation studies on the proposed intrinsic drug-resistant mechanism and candidate genes are needed using in vivo data from either patient-derived xenograft models or clinical chemotherapy trials.

Abstract 4246: Association of transcriptional levels of folate-mediated one-carbon metabolism related genes in cancer cell lines with drug treatment response

Folate-mediated one-carbon metabolism (OCM) is essential for growth and survival of cancer cells. It affects biosynthesis of nucleotides and amino acids, regulation of redox status, methylation of nucleic acids and proteins, and genome maintenance. We investigated whether the response of cancer cells to antitumor therapy treatment may be partially influenced by variation in expression of one-carbon metabolism genes. We used publicly available gene expression data and drug response measures for 251 antitumor agents in 635 cancer cell lines with matching information from the Cancer Cell Line Encyclopedia and the Genomics of Drug Sensitivity in Cancer resources. We examined whether pre-treatment expression levels of OCM-related genes were associated with drug response. Among the 34 OCM genes examined, expression of GART, TYMS, SHMT2, MTR, ALDH2, BHMT, MAT2B, MTHFD2, NNMT, and SLC46A1 showed modest correlations with response to treatment with a variety of antitumor agents. Higher expression levels of the SLC46A1 transporter gene were associated with resistance to multiple drugs, whereas elevated expression of GART, TYMS, SHMT2, MTR, BHMT, and MAT2B was associated with chemosensitivity to multiple antitumor agents. NNMT expression was bimodally distributed and showed different directions of association with various agents. Correlation of increased NNMT expression with sensitivity to dasatinib was validated in the NCI-60 cancer cell line panel. Expression of several OCM genes was strongly associated with expression of multiple components of drug target pathways. For example, expression of both TYMS and GART was strongly positively correlated with BRCA1 expression, NNMT expression was associated with expression of multiple drug target genes including EGFR and ABL2, and the expression of TYMS, DHFR, and SHMT1 was positively correlated with AURKB expression. Pretreatment expression levels of many OCM genes including DHFR, TYMS, ATIC, GART, AHCY, MTHFD1, SLC19A1, and multiple other genes were positively correlated with each other, suggesting their co-regulation. In contrast, NNMT expression was negatively correlated with expression of several other OCM genes. Further studies could investigate whether correlations of expression levels of individual OCM genes with drug response are related to specific metabolic roles of these genes or whether such associations may be due to the general increase in cellular growth and proliferation and tumor progression, which may affect sensitivity to cancer treatment.

Citation Format: Julia Krushkal, Suleyman Vural, Dong-Joon Min. Association of transcriptional levels of folate-mediated one-carbon metabolism related genes in cancer cell lines with drug treatment response [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4246.

Birinapant (TL32711) Improves Responses to GEM/AZD7762 Combination Therapy in Triple-negative Breast Cancer Cell Lines

BACKGROUND

Triple-negative breast cancer (TNBC) is an aggressive form of breast cancer currently lacking targeted therapies. Our previous work demonstrated a therapeutic synergism with gemcitabine (GEM) and the CHK1 inhibitor (AZD7762) combination treatment in a TNBC cell line. We hypothesized that the response to this combination therapy would differ among heterogeneous TNBC patients and that addition of a SMAC mimetic (TL32711) could improve efficacy.

MATERIALS AND METHODS

Therapeutic responses to GEM, GEM/AZD7762, and GEM/AZD7762/TL32711 combinations were investigated by XTT assays and western blotting of cell cycle and apoptosis-related proteins in ten TNBC cell lines.

RESULTS

TNBC cell lines harboring low levels of endogenous CHK1, cIAP1 and cIAP2 were responsive to GEM alone, whereas cell lines demonstrating a minimal increase in phospho-S345 CHK1 after treatment were responsive to GEM/AZD7762 or GEM/AZD7762/TL32711 combination.

CONCLUSION

The response of TNBC cells to particular therapies varies and will require development of predictive biomarkers.

Abstract 1046: The histone methyl transferase MMSET/WHSC1 promotes an epithelial-mesenchymal transition and invasive properties of prostate cancer

Prostate cancer (PCa) remains the most common neoplasia diagnosed among men in the USA, and the second leading cause of cancer deaths. Recent evidence has indicated that epigenetic alterations contribute to the initiation and progression of PCa; however, the mechanisms by which chromatin modifiers influence this disease are still poorly understood. The histone methyl transferase MMSET (Multiple Myeloma Set Domain) is overexpressed in a number of different tumor types, including PCa. While the precise mechanism of MMSET action is still not well defined, it is believed to involve alteration of chromatin structure through dimethylation of lysine 36 on histone H3 (H3K36me2). Analysis of microarray databases indicates that MMSET expression rises in the progression from benign prostatic epithelium to localized and metastatic PCa. We found that PCa cell lines express significantly higher levels of MMSET compared to immortalized but non-transformed prostate cells. In t(4;14)+ myelomas, MMSET overexpression changes global levels of histone modifications, promoting H3K36me2, and repressing trimethylation of lysine 27 (H3K27me3). Similarly, H3K36me2 and H3K27me3 levels in PCa cell lines depended on the expression of MMSET, while depletion of MMSET in benign prostatic epithelial cells did not affect chromatin modifications. Knockdown of MMSET in DU145 and PC-3 tumor cells decreased soft agar colony formation and cell proliferation. Furthermore, inhibition of MMSET expression strikingly decreased cell migration and invasion, while overexpression of MMSET in immortalized non-transformed RWPE-1 cells promoted migratory and invasive properties. These findings suggest that high levels of MMSET play a pathogenic role in PCa progression. Overexpression of MMSET in RWPE-1 cells was accompanied by an epithelial to mesenchymal transition (EMT), characterized by a change in cell morphology and increased expression of mesenchymal markers vimentin and N-cadherin. Among a panel of EMT promoting genes analyzed, Twist1 expression was strongly regulated by MMSET both in the knockdown and the overexpression models. Chromatin immunoprecipitation analysis demonstrated that MMSET binds to the Twist1 locus, leading to an increase in H3K36me2 and a decrease in the repressive mark H3K27me3, suggesting a direct role of MMSET in regulation of Twist1. siRNA depletion of Twist1 in MMSET-overexpressing RWPE-1 cells blocked invasion, indicating that Twist1 was a critical target of MMSET responsible for the acquisition of EMT properties. Intriguingly, Twist1 expression was also elevated in a panel of myeloma cell lines overexpressing MMSET due to chromosomal translocation t(4;14). Collectively, these data suggest that MMSET has a critical role in cancer pathogenesis and progression through epigenetic regulation of metastasis-related genes.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 1046. doi:1538-7445.AM2012-1046

Partners in crime: Genes within an amplicon collude to globally deregulate chromatin in lymphoma

In this issue of Cancer Cell, Rui et al. identify JAK2 and JMJDC2 as two contiguous, coamplified oncogenes in primary mediastinal B cell and Hodgkin lymphoma. Together, JAK2 and JMJD2C induce major changes in chromatin structure and gene expression. Targeting these proteins with small molecules represents a new avenue for therapy.

Transcriptional profiling of polycythemia vera identifies gene expression patterns both dependent and independent from the action of JAK2V617F

PURPOSE

To understand the changes in gene expression in polycythemia vera (PV) progenitor cells and their relationship to JAK2V617F.

EXPERIMENTAL DESIGN

Messenger RNA isolated from CD34(+) cells from nine PV patients and normal controls was profiled using Affymetrix arrays. Gene expression change mediated by JAK2V617F was determined by profiling CD34(+) cells transduced with the kinase and by analysis of leukemia cell lines harboring JAK2V617F, treated with an inhibitor.

RESULTS

A PV expression signature was enriched for genes involved in hematopoietic development, inflammatory responses, and cell proliferation. By quantitative reverse transcription-PCR, 23 genes were consistently deregulated in all patient samples. Several of these genes such as WT1 and KLF4 were regulated by JAK2, whereas others such as NFIB and EVI1 seemed to be deregulated in PV by a JAK2-independent mechanism. Using cell line models and comparing gene expression profiles of cell lines and PV CD34(+) PV specimens, we have identified panels of 14 JAK2-dependent genes and 12 JAK2-independent genes. These two 14- and 12-gene sets could separate not only PV from normal CD34(+) specimens, but also other MPN such as essential thrombocytosis and primary myelofibrosis from their normal counterparts.

CONCLUSIONS

A subset of the aberrant gene expression in PV progenitor cells can be attributed to the action of the mutant kinase, but there remain a significant number of genes characteristic of the disease but deregulated by as yet unknown mechanisms. Genes deregulated in PV as a result of the action of JAK2V617F or independent of the kinase may represent other targets for therapy.

Gene expression signatures predictive of early response and outcome in high-risk childhood acute lymphoblastic leukemia: A Children's Oncology Group Study [corrected]

PURPOSE

To identify children with acute lymphoblastic leukemia (ALL) at initial diagnosis who are at risk for inferior response to therapy by using molecular signatures.

PATIENTS AND METHODS

Gene expression profiles were generated from bone marrow blasts at initial diagnosis from a cohort of 99 children with National Cancer Institute-defined high-risk ALL who were treated uniformly on the Children's Oncology Group (COG) 1961 study. For prediction of early response, genes that correlated to marrow status on day 7 were identified on a training set and were validated on a test set. An additional signature was correlated with long-term outcome, and the predictive models were validated on three large, independent patient cohorts. Results We identified a 24-probe set signature that was highly predictive of day 7 marrow status on the test set (P = .0061). Pathways were identified that may play a role in early blast regression. We have also identified a 47-probe set signature (which represents 41 unique genes) that was predictive of long-term outcome in our data set as well as three large independent data sets of patients with childhood ALL who were treated on different protocols. However, we did not find sufficient evidence for the added significance of these genes and the derived predictive models when other known prognostic features, such as age, WBC, and karyotype, were included in a multivariate analysis.

CONCLUSION

Genes and pathways that play a role in early blast regression may identify patients who may be at risk for inferior responses to treatment. A fully validated predictive gene expression signature was defined for high-risk ALL that provided insight into the biologic mechanisms of treatment failure.

Diverse pathways mediate chemotherapy-induced cell death in acute lymphoblastic leukemia cell lines

Cancer cell resistance to chemotherapy may be mediated by defects in apoptotic pathways. A prior study showed that in vivo apoptosis of Acute Lymphoblastic Leukemia (ALL) blasts in response to chemotherapy could occur through diverse pathways including both p53-dependent and -independent mechanisms. In this study we investigated the apoptotic response in more detail by using a panel of ALL cell lines that differed in respect to p53 status. Upon exposure to a uniform stimulus, expression of apoptotic proteins, including the effector caspase-3, varied among ALL cell lines partly depending on p53 transcriptional activity and caspase-8 activation. Although the expression and contribution to apoptosis differed among known members of the apoptotic pathway, apoptosis was universally mediated by mitochondrial depolarization. The NFkappaB pathway was activated in response to chemotherapy but NFkappaB inhibition appeared to not influence chemosensitivity. This study further documents the highly variable nature of cell death programs in ALL and provides the foundation for cell death pathway modulation to improve ALL cure rates without increasing chemotherapy-related toxicity.

Biologic pathways associated with relapse in childhood acute lymphoblastic leukemia: a Children's Oncology Group study

Outcome for children with childhood acute lymphoblastic leukemia (ALL) who relapse is poor. To gain insight into the mechanisms of relapse, we analyzed gene-expression profiles in 35 matched diagnosis/relapse pairs as well as 60 uniformly treated children at relapse using the Affymetrix platform. Matched-pair analyses revealed significant differences in the expression of genes involved in cell-cycle regulation, DNA repair, and apoptosis between diagnostic and early-relapse samples. Many of these pathways have been implicated in tumorigenesis previously and are attractive targets for intervention strategies. In contrast, no common pattern of changes was observed among late-relapse pairs. Early-relapse samples were more likely to be similar to their respective diagnostic sample while we noted greater divergence in gene-expression patterns among late-relapse pairs. Comparison of expression profiles of early- versus late-relapse samples indicated that early-relapse clones were characterized by overexpression of biologic pathways associated with cell-cycle regulation. These results suggest that early-relapse results from the emergence of a related clone, characterized by the up-regulation of genes mediating cell proliferation. In contrast, late relapse appears to be mediated by diverse pathways.

Gene expression profiling reveals intrinsic differences between T-cell acute lymphoblastic leukemia and T-cell lymphoblastic lymphoma

BACKGROUND

T-cell acute lymphoblastic leukemia (T-ALL) and T-cell lymphoblastic lymphoma (T-LL) and are often thought to represent a spectrum of a single disease. The malignant cells in T-ALL and T-LL are morphologically indistinguishable, and they share the expression of common cell surface antigens and cytogenetic characteristics. However, despite these similarities, differences in the clinical behavior of T-ALL and T-LL are observed.

PROCEDURE

We analyzed the gene expression profiles of T-ALL and T-LL samples obtained from Children's Oncology Group (COG) tumor banks using DNA arrays. Immunohistochemistry was also performed to validate the expression of selected targets.

RESULTS

Unsupervised hierarchical clustering of all samples showed complete segregation of T-ALL and T-LL into distinct clusters. Next, we identified the top 201 genes that best differentiated T-ALL from T-LL using significance analysis of microarrays (SAM), a supervised statistical approach. Genes representing several functional groups were differentially expressed in T-LL and T-ALL. Prediction analysis of microarrays (PAM) identified a subset of genes, which accurately classified all 19 T-ALL and T-LL samples with an overall misclassification error rate of 0. Immunohistochemical validation of protein expression of selected genes identified by microarray analysis confirmed overexpression of MLL-1 in T-LL tumor cells compared to T-ALL and CD47 in T-ALL tumors cells when compared to T-LL.

CONCLUSIONS

Despite significant similarities between the malignant T-cell precursors, clear differences in the gene expression profiles were observed between T-ALL and T-LL implying underlying differences in the biology of the two entities.

Childhood acute lymphoblastic leukemia in the age of genomics

The recent sequencing of the human genome and technical breakthroughs now make it possible to simultaneously determine mRNA expression levels of almost all of the identified genes in the human genome. DNA "chip" or microarray technology holds great promise for the development of more refined, biologically-based classification systems for childhood ALL, as well as the identification of new targets for novel therapy. To date gene expression profiles have been described that correlate with subtypes of ALL defined by morphology, immunophenotype, cytogenetic alterations, and response to therapy. Mechanistic insights into treatment failure have come from the definition of mRNA signatures that predict in vitro chemoresistance, as well as differences between blasts at relapse and new diagnosis. New bioinformatics tools optimize data mining, but validation of findings is essential since "over-fitting" the data is a common danger. In the future, genomic analysis will be complemented by evaluation of the cancer proteome.

Site-Specific Cross-Linking of Proteins through Tyrosine Hexahistidine Tags

The genetic addition of hexahistidine (H(6)) tags is widely used to isolate recombinant proteins by immobilized metal-affinity chromatography (IMAC). Addition of a tyrosine residue to H(6) tags enabled proteins to be covalently cross-linked under mild conditions in a manner similar to the natural, site-specific cross-linking of tyrosines into dityrosine. A series of seven hexahistidine tags with tyrosines placed in various positions (H(6)Y tags) were added to the amino terminus of the I28 immunoglobulin domain of the human cardiac titin. The H(6)Y-tagged I28 dimerized in the presence of excess Ni(2+) with a K(D) of 200 microM. Treatment of Ni(2+)-dimerized H(6)Y-I28 with an oxidant, monoperoxyphthalic acid (MMPP) or sodium sulfite, resulted in covalent protein multimerization through chelated Ni(2+)-catalyzed cross-linking of the Y residues engineered into the H(6) tag. The protein oligomerization was observed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS PAGE). The presence of dityrosine in the cross-linked proteins was confirmed by fluorescence emission at 410 nm. Proteins lacking the Y residue in the H(6) tag treated with the same oxidative conditions did not cross-link or exhibit dityrosine fluorescence, despite the presence of an endogenous Y residue. The method may have potential uses in other protein conjugation applications such as protein labeling and interfacial immobilization of proteins on artificial surfaces.

Individualized therapy for childhood acute lymphoblastic leukemia

In the field of oncology, a growing emphasis is now being placed on individualizing treatment in a way that maximizes chance for cure while minimizing unwanted side effects. In childhood acute lymphoblastic leukemia (ALL), several well-established clinical and biologic prognostic variables have traditionally been used to risk stratify therapy for individual patients. While this approach has been very successful, many relapses still occur unpredictably in patients characterized as having favorable features of their disease at diagnosis. Furthermore, it is likely that other children are overtreated. Therefore, current initiatives in childhood leukemia have focused on identifying new prognostic markers to refine treatment decision-making. Recent advances, which include the sequencing of the human genome, and technical developments in high-throughput genomics and proteomics, have facilitated these efforts. This review will chart the evolution of individualized therapy for ALL, the most common malignancy of children.

Pediatric acute lymphoblastic leukemia

The outcome for children with acute lymphoblastic leukemia (ALL) has improved dramatically with current therapy resulting in an event free survival exceeding 75% for most patients. However significant challenges remain including developing better methods to predict which patients can be cured with less toxic treatment and which ones will benefit from augmented therapy. In addition, 25% of patients fail therapy and novel treatments that are focused on undermining specifically the leukemic process are needed urgently. In Section I, Dr. Carroll reviews current approaches to risk classification and proposes a system that incorporates well-established clinical parameters, genetic lesions of the blast as well as early response parameters. He then provides an overview of emerging technologies in genomics and proteomics and how they might lead to more rational, biologically based classification systems. In Section II, Drs. Mary Relling and Stella Davies describe emerging findings that relate to host features that influence outcome, the role of inherited germline variation. They highlight technical breakthroughs in assessing germline differences among patients. Polymorphisms of drug metabolizing genes have been shown to influence toxicity and the best example is the gene thiopurine methyltransferase (TPMT) a key enzyme in the metabolism of 6-mercaptopurine. Polymorphisms are associated with decreased activity that is also associated with increased toxicity. The role of polymorphisms in other genes whose products play an important role in drug metabolism as well as cytokine genes are discussed. In Sections III and IV, Drs. James Downing and Cheryl Willman review their findings using gene expression profiling to classify ALL. Both authors outline challenges in applying this methodology to analysis of clinical samples. Dr. Willman describes her laboratory's examination of infant leukemia and precursor B-ALL where unsupervised approaches have led to the identification of inherent biologic groups not predicted by conventional morphologic, immunophenotypic and cytogenetic variables. Dr. Downing describes his results from a pediatric ALL expression database using over 327 diagnostic samples, with 80% of the dataset consisting of samples from patients treated on a single institutional protocol. Seven distinct leukemia subtypes were identified representing known leukemia subtypes including: BCR-ABL, E2A-PBX1, TEL-AML1, rearrangements in the MLL gene, hyperdiploid karyotype (i.e., > 50 chromosomes), and T-ALL as well as a new leukemia subtype. A subset of genes have been identified whose expression appears to be predictive of outcome but independent verification is needed before this type of analysis can be integrated into treatment assignment. Chemotherapeutic agents kill cancer cells by activating apoptosis, or programmed cell death. In Section V, Dr. John Reed describes major apoptotic pathways and the specific role of key proteins in this response. The expression level of some of these proteins, such as BCL2, BAX, and caspase 3, has been shown to be predictive of ultimate outcome in hematopoietic tumors. New therapeutic approaches that modulate the apoptotic pathway are now available and Dr. Reed highlights those that may be applicable to the treatment of childhood ALL.

Anti-nucleosome antibody: significance in lupus patients lacking anti-double-stranded DNA antibody

OBJECTIVE

To investigate the clinical significance of anti-nucleosome antibodies in SLE patients lacking anti-double stranded DNA (dsDNA) antibodies.

METHODS

IgG anti-nucleosome antibodies were detected by enzyme-linked immunosorbent assays (ELISA) in the sera of SLE patients. Anti-dsDNA antibodies were measured by Farr assays and ELISA, not only in the samples taken for anti-nucleosome testing, but also in sera obtained regularly during the follow-up.

RESULTS

Ninety-eight (76.0%) out of 129 patients with SLE had anti-nucleosome antibodies. Twenty-five patients (19.4%) consistently showed little or no anti-dsDNA reactivity during the course of their disease, and among these anti-nucleosome antibodies were present in the sera of 15 (60.0%). Of the patients with anti-dsDNA-negative SLE, renal disorders were present in 8 patients (32.0%), all of whom had anti-nucleosome antibodies. Renal disorders were not found in patients (n = 10) who had neither anti-dsDNA nor anti-nucleosome antibodies. Other autoantibodies such as anti-Ro, anti-Sm and anti-cardiolipin were not associated with renal disorders in this group. The levels of anti-nucleosome antibody strongly correlated with the SLEDAI scores, but inversely correlated with serum complement levels in anti-dsDNA negative SLE patients.

CONCLUSION

Our data suggest that the anti-nucleosome antibody may be a useful marker for diagnosis and activity assessment of anti-dsDNA negative SLE. Anti-nucleosome antibody may be an important factor for renal involvement in this subgroup of patients.

The kinetics of circulating cytokines including IL-6, TNF-alpha, IL-8 and IL-10 following allogeneic hematopoietic stem cell transplantation

Pro-inflammatory (IL-6, TNFalpha and IL-8) and anti-inflammatory (IL-10) cytokines were determined in weekly samples from 52 patients undergoing allogeneic hematopoietic stem cell transplantation (HSCT). IL-6 increased immediately after transplant peaking at week +3, but IL-8 concentrations were elevated only during week +1. After a slight decrease in week +1, TNF-alpha significantly increased from week +2 and peaked at week +3, whereas, IL-10 values started to rise in week +2 and peaked during week +4. IL-6 and TNF-alpha were positively correlated from week +2 to week +4, and IL-6 levels at week +1 were related with fever and severe stomatitis. Serum levels of IL-6 at week +1 and IL-10 at week +4 were significantly higher in patients with early transplant-related complications, such as fever, severe stomatitis or acute GVHD > or = overall grade II than in those without the complications. We conclude that a high serum IL-6 level at week +1 may be an early predictor of transplant-related complications and that it seems to trigger pro- and anti-inflammatory cytokine release. Kinetic patterns of IL-6 and IL-10 were more exaggerated in those with complications after HSCT.

Vascular endothelial growth factor levels in the serum and synovial fluid of patients with rheumatoid arthritis

OBJECTIVE

To determine the vascular endothelial growth factor (VEGF) concentrations in serum and synovial fluid (SF) from patients with rheumatoid arthritis (RA) and to search for relationships between VEGF levels and clinical and laboratory variables.

METHODS

We measured VEGF levels using an enzyme-linked immunosorbent assay. Serum samples were obtained from 99 RA patients, 49 osteoarthritis (OA) patients, and 80 normal controls. Paired samples of serum and SF were collected from 32 patients with RA and 15 with OA.

RESULTS

The mean serum VEGF concentration was 590.1 pg/ml for RA patients, 286.7 pg/ml for OA patients, and 265.8 pg/ml in controls. The serum VEGF concentration was significantly higher in the RA patients than in the OA patients or the controls (both p < 0.001). Furthermore, the VEGF levels in SF from RA patients were significantly higher than in SF from OA patients (p = 0.017). However, there was no correlation between VEGF levels in serum and SF from the same RA patients. The serum VEGF concentration was correlated with the ESR, serum CRP concentration, serum rheumatoid factor, number of tender and swollen joints, Modified Health Assessment Questionnaire, and patient and physician global assessments of disease activity in RA patients.

CONCLUSION

These results suggest that VEGF level is related to RA disease activity, suggesting that VEGF may play some role in the pathogenesis of RA.

Decreased production of interleukin-12 and interferon-gamma is associated with renal involvement in systemic lupus erythematosus

OBJECTIVE

To analyze the type 1/type 2 cytokine balance in patients with systemic lupus erythematosus (SLE) according to the presence of renal disorder and activity status.

METHODS

We measured the serum levels of type 1 (IFN-gamma, IL-12) and type 2 cytokines (IL-4, IL-10) as well as spontaneous and stimulated cytokine production from peripheral blood mononuclear cells (PBMC) in 40 patients with SLE.

RESULTS

Patients with lupus nephritis (LN) showed significantly lower levels of serum IL-12 and IFN-gamma than those without LN. Production of IL-12 and IFN-gamma by stimulated PBMC were also decreased in patients with LN. The circulating IL-12 correlated positively with IFN-gamma, but inversely with IL-10. The SLEDAI scores correlated well with the ratio of IL-4/IFN-gamma levels.

CONCLUSION

The reduced production of IL-12 and IFN-gamma and the resultant shift towards the type 2 cytokine phenotype may be associated with LN.

Shift toward T helper 1 cytokines by type II collagen-reactive T cells in patients with rheumatoid arthritis

OBJECTIVE

To investigate the impact of type II collagen (CII)-reactive T cells on the Th1/Th2 cytokine balance in patients with rheumatoid arthritis (RA).

METHODS

T cell proliferative responses to bovine CII were examined in synovial fluid mononuclear cells (SFMC) and peripheral blood mononuclear cells (PBMC) by mixed lymphocyte culture. CII-reactive T cell lines were generated from the SFMC and PBMC. Interferon-gamma (IFNgamma), interleukin-12 (IL-12), and IL-4 were measured by enzyme-linked immunosorbent assay in the SF, sera, and culture supernatants of PBMC and SFMC that had been stimulated with CII.

RESULTS

The frequency of CII-reactive T cells was higher in the PBMC from RA patients than in that from osteoarthritis patients and healthy control subjects. In RA patients, CII-reactive T cells were more prevalent in SFMC than in PBMC. The mean level of IFNgamma and the ratio of IFNgamma to IL-4 were significantly higher in the culture supernatants of T cells stimulated with CII; these differences were more prominent in SFMC. Levels of IL-12 in the culture supernatants of SFMC and PBMC stimulated with CII were significantly higher than those in unstimulated supernatants. T cell responsiveness correlated well with the level of type 1 cytokines in culture supernatants from RA T cells stimulated with CII. In the CII-reactive cell lines, the increased production of IFNgamma was consistent with clonal expansion.

CONCLUSION

CII-reactive T cells are more abundant in SFMC than in PBMC and are strongly associated with a shift toward Thl cytokine in the inflamed joints of RA patients. Our results suggest that a skewing toward type 1 cytokines by CII-reactive T cells may play an important role in the chronic inflammatory process of RA.

CD40 engagement on synovial fibroblast up-regulates production of vascular endothelial growth factor

We tested the impact of CD40 engagement on the production of vascular endothelial growth factor (VEGF) from rheumatoid synovial fibroblasts. Fibroblast-like synovial cells (FLS) were prepared from the synovial tissues of rheumatoid arthritis patients and cultured in the presence of CD40 ligand-transfected (CD40L+) L cells. VEGF levels were determined in the culture supernatants by ELISA. Stimulation of FLS by CD40L+ L cells increased the production of VEGF by 4.1-fold over the constitutive levels of unstimulated FLS. The CD40L on activated T cells from rheumatoid synovial fluid also up-regulated VEGF production from FLS. Neither indomethacin nor Abs to IL-1beta, TNF-alpha, and TGF-beta did affect CD40L-induced VEGF production. Stimulation of FLS with TNF-alpha, IL-1beta, and TGF-beta increased VEGF production by 1.6-, 2.0-, and 5.2-fold, respectively, and displayed an additive effect on the production of VEGF by CD40L. VEGF mRNA expression was also up-regulated by the stimulation of FLS with membranes from the CD40L+ L cells. Dexamethasone completely abrogated CD40L-induced VEGF production. In addition, pyrrolidine dithiocarbamate partially down-regulated CD40L-induced VEGF production, showing that the NF-kappaB pathway was partly involved in the signaling of CD40L leading to VEGF production. Collectively, these results suggest that the interaction between CD40 on synovial fibroblasts and CD40L expressed on activated T lymphocytes may be directly involved in the neovascularization in rheumatoid synovitis by enhancing the production of VEGF.

The role of IL-12 in inflammatory activity of patients with rheumatoid arthritis (RA)

The aim of this study was to investigate the role of IL-12 in patients with RA. IL-12 (p70) and its associated cytokines were measured in sera and synovial fluid (SF) using an enzyme-linked immunosorbent method. Seven American College of Rheumatology (ACR) core set measures as well as IL-12 levels were sequentially monitored at the commencement and 4 months after treatment with a low-dose steroid and disease-modifying anti-rheumatic drugs (DMARDs). In sera, 64 (42.2%) of 152 RA patients had detectable concentrations of IL-12 (p70), whereas one (1.4%) of 69 osteoarthritis (OA) patients and five (10%) of 50 healthy controls had detectable IL-12 (P < 0.001). The median level of circulating IL-12 was also higher in RA patients (P < 0.001). In SF, the number of patients with detectable IL-12 and the median IL-12 levels were significantly higher in RA patients (n = 53) than in OA patients (n = 22). In paired samples (n = 53) of sera and SF from RA patients, IL-12 levels were higher in the SF than in sera (P < 0.001). Patients with detectable IL-12 (n = 51) in sera had higher tender joint scores (P = 0.003), swollen joint scores (P < 0.001) and C-reactive protein (CRP; P = 0.036), than those without (n = 55). Four months after treatment with DMARDs, the improved group showed a larger IL-12 decrease than the non-improved group (P = 0.017). The levels of IL-12 correlated positively with those of IL-2, interferon-gamma, IL-6, and tumour necrosis factor-alpha, but were correlated inversely with those of IL-10. Our results demonstrate that IL-12 levels reflect RA disease activity and that IL-12 is involved in the production of proinflammatory cytokines. An IL-12 blockade could be useful for the treatment of RA.

Specific immobilization of in vivo biotinylated bacterial luciferase and FMN:NAD(P)H oxidoreductase

Bacterial bioluminescence, catalyzed by FMN:NAD(P)H oxidoreductase and luciferase, has been used as an analytical tool for quantitating the substrates of NAD(P)H-dependent enzymes. The development of inexpensive and sensitive biosensors based on bacterial bioluminescence would benefit from a method to immobilize the oxidoreductase and luciferase with high specific activity. Toward this end, oxidoreductase and luciferase were fused with a segment of biotin carboxy carrier protein and produced in Escherichia coli. The in vivo biotinylated luciferase and oxidoreductase were immobilized on avidin-conjugated agarose beads with little loss of activity. Coimmobilized enzymes had eight times higher bioluminescence activity than the free enzymes at low enzyme concentration and high NADH concentration. In addition, the immobilized enzymes were more stable than the free enzymes. This immobilization method is also useful to control enzyme orientation, which could increase the efficiency of sequentially operating enzymes like the oxidoreductase-luciferase system.

Behavior of Model Proteins, Pretreated in Urea and/or Dithiothreitol, at Air/Solution Interfaces

The behavior of the model proteins, lysozyme, myoglobin, and beta-casein, pretreated in urea and/or dithiothreitol, at air/solution interfaces was studied by surface pressure-area techniques. The data suggested that in the absence of pretreatments the globular proteins are only partially unfolded at the interfaces. The interfacial activity was enhanced by the pretreatment (lysozyme in 8 M urea with 0.2 M dithiothreitol and myoglobin in 8 M urea). The interfacial activity of casein, a random-coil type protein, was not influenced by the pretreatment (8 M urea), as it readily and completely unfolds at the interfaces. The unfolding of globular proteins at the interfaces is apparently restricted by both disulfide and noncovalent bonds. Pretreatment can relax those restrictions, resulting in more complete interfacial unfolding. Copyright 1998 Academic Press. Copyright 1998Academic Press