Elena V. Komissarova

Evaluation of fetuses in a study of intravenous immunoglobulin as preventive therapy for congenital heart block: Results of a multicenter, prospective, open-label clinical trial†

OBJECTIVE The recurrence rate of anti-SSA/Ro-associated congenital heart block (CHB) is 17%. Sustained reversal of third-degree block has never been achieved. Based on potential reduction of maternal autoantibody titers as well as fetal inflammatory responses, intravenous immunoglobulin (IVIG) was evaluated as preventive therapy for CHB. METHODS A multicenter, prospective, open-label study based on Simons 2-stage optimal design was initiated. Enrollment criteria included the presence of anti-SSA/Ro antibodies in the mother, birth of a previous child with CHB/neonatal lupus rash, current treatment with < or = 20 mg/day of prednisone, and <12 weeks pregnant. IVIG (400 mg/kg) was given every 3 weeks from week 12 to week 24 of gestation. The primary outcome was the development of second-degree or third-degree CHB. RESULTS Twenty mothers completed the IVIG protocol before the predetermined stopping rule of 3 cases of advanced CHB in the study was reached. CHB was detected at 19, 20, and 25 weeks; none of the cases occurred following the finding of an abnormal PR interval on fetal Doppler monitoring. One of these mothers had 2 previous children with CHB. One child without CHB developed a transient rash consistent with neonatal lupus. Sixteen children had no manifestations of neonatal lupus at birth. No significant changes in maternal titers of antibody to SSA/Ro, SSB/La, or Ro 52 kd were detected over the course of therapy or at delivery. There were no safety issues. CONCLUSION This study establishes the safety of IVIG and the feasibility of recruiting pregnant women who have previously had a child with CHB. However, IVIG at low doses consistent with replacement does not prevent the recurrence of CHB or reduce maternal antibody titers.

Ro60-Associated Single-Stranded RNA Links Inflammation with Fetal Cardiac Fibrosis via Ligation of TLRs: A Novel Pathway to Autoimmune-Associated Heart Block

Activation of TLR by ssRNA after FcγR-mediated phagocytosis of immune complexes (IC) may be relevant in autoimmune-associated congenital heart block (CHB) where the obligate factor is a maternal anti-SSA/Ro Ab and the fetal factors, protein/RNA on an apoptotic cardiocyte and infiltrating macrophages. This study addressed the hypothesis that Ro60-associated ssRNAs link macrophage activation to fibrosis via TLR engagement. Both macrophage transfection with noncoding ssRNA that bind Ro60 and an IC generated by incubation of Ro60-ssRNA with an IgG fraction from a CHB mother or affinity purified anti-Ro60 significantly increased TNF-α secretion, an effect not observed using control RNAs or normal IgG. Dependence on TLR was supported by the significant inhibition of TNF-α release by IRS661 and chloroquine. The requirement for FcγRIIIa-mediated delivery was provided by inhibition with an anti-CD16a Ab. Fibrosis markers were noticeably increased in fetal cardiac fibroblasts after incubation with supernatants generated from macrophages transfected with ssRNA or incubated with the IC. Supernatants generated from macrophages with ssRNA in the presence of IRS661 or chloroquine did not cause fibrosis. In a CHB heart, but not a healthy heart, TLR7 immunostaining was localized to a region near the atrioventricular groove at a site enriched in mononuclear cells and fibrosis. These data support a novel injury model in CHB, whereby endogenous ligand, Ro60-associated ssRNA, forges a nexus between TLR ligation and fibrosis instigated by binding of anti-Ro Abs to the target protein likely accessible via apoptosis.

Arsenite induced poly(ADP-ribosyl)ation of tumor suppressor P53 in human skin keratinocytes as a possible mechanism for carcinogenesis associated with arsenic exposure

Arsenite is an environmental pollutant. Exposure to inorganic arsenic in drinking water is associated with elevated cancer risk, especially in skin. Arsenite alone does not cause skin cancer in animals, but arsenite can enhance the carcinogenicity of solar UV. Arsenite is not a significant mutagen at non-toxic concentrations, but it enhances the mutagenicity of other carcinogens. The tumor suppressor protein P53 and nuclear enzyme PARP-1 are both key players in DNA damage response. This laboratory demonstrated earlier that in cells treated with arsenite, the P53-dependent increase in p21(WAF1/CIP1) expression, normally a block to cell cycle progression after DNA damage, is deficient. Here we show that although long-term exposure of human keratinocytes (HaCaT) to a nontoxic concentration (0.1 microM) of arsenite decreases the level of global protein poly(ADP-ribosyl)ation, it increases poly(ADP-ribosyl)ation of P53 protein and PARP-1 protein abundance. We also demonstrate that exposure to 0.1 microM arsenite depresses the constitutive expression of p21 mRNA and P21 protein in HaCaT cells. Poly(ADP-ribosyl)ation of P53 is reported to block its activation, DNA binding and its functioning as a transcription factor. Our results suggest that arsenites interference with activation of P53 via poly(ADP-ribosyl)ation may play a role in the comutagenic and cocarcinogenic effects of arsenite.

Transcription-coupled DNA Repair Is Genomic Context-dependent

DNA damage is preferentially repaired in the transcribed strand of many active genes. Although the concept of DNA repair coupled with transcription has been widely accepted, its mechanisms remain elusive. We recently reported that in Chinese hamster ovary cells while ultraviolet light-induced cyclobutane pyrimidine dimers (CPDs) are preferentially repaired in the transcribed strand of dihydrofolate reductase gene, CPDs are efficiently repaired in both strands of adenine phosphoribosyltransferase (APRT) locus, in either a transcribed or nontranscribed APRT gene (1). These results suggested that the transcription dependence of repair may depend on genomic context. To test this hypothesis, we constructed transfectant cell lines containing a single, actively transcribedAPRT gene, integrated at different genomic sites. Mapping of CPD repair in the integrated APRT genes in three transfectant cell lines revealed two distinct repair patterns, either preferential repair of CPDs in the transcribed strand or very poor repair in both strands. Similar kinetics of micrococcal nuclease digestion were seen for all three transfectant APRT gene domains and endogenous APRT locus. Our results suggest that both the efficiency and strand-specificity of repair of an actively transcribed gene are profoundly affected by genomic context but do not reflect changes in first order nucleosomal structure.

fau and its ubiquitin-like domain (FUBI) transforms human osteogenic sarcoma (HOS) cells to anchorage-independence

Arsenite is the most likely carcinogenic form of arsenic in the environment. Previously, expression cloning for cDNAs whose overexpression confers arsenite-resistance in Chinese hamster V79 cells identified two genes: fau and a novel gene, asr2. The fau gene encodes a ubiquitin-like protein (here called FUBI) fused to the ribosomal S30 protein. Since the expression of the fox sequence (antisense to fau) increased the tumorigenicity of a mouse sarcoma virus, it was proposed that fau might be a tumor suppressor gene. We intended to test its ability to block arsenite-induced transformation of human osteogenic sarcoma (HOS) cells to anchorage-independence. Instead, we found that overexpressing fau itself was able to transform HOS cells. When the two domains were expressed separately, only FUBI was transforming and only the S30 domain conferred arsenite resistance. An incidental finding was the transforming activity of the selectable marker, hyg. FUBI belongs to the ubiquitin-like protein group that is capable of forming conjugates to other proteins, although none have so far been identified. Alternatively, FUBI may act as a substitute or inhibitor of ubiquitin, to which it is most closely related, or to close ubiquitin-like relatives UCRP, FAT10, and/or Nedd8.

High-definition CpG methylation of novel genes in gastric carcinogenesis identified by next-generation sequencing

Gastric cancers are the most frequent gastric malignancy and usually arise in the sequence of Helicobacter pylori-associated chronic gastritis. CpG methylation is a central mechanism of epigenetic gene regulation affecting cancer-related genes, and occurs early in gastric carcinogenesis. DNA samples from non-metaplastic gastric mucosa with variable levels of gastritis (non-metaplastic mucosa), intestinal metaplasia, or gastric cancer were screened with methylation arrays for CpG methylation of cancer-related genes and 30 gene targets were further characterized by high-definition bisulfite next-generation sequencing. In addition, data from The Cancer Genome Atlas were analyzed for correlation of methylation with gene expression. Overall, 13 genes had significantly increased CpG methylation in gastric cancer vs non-metaplastic mucosa (BRINP1, CDH11, CHFR, EPHA5, EPHA7, FGF2, FLI1, GALR1, HS3ST2, PDGFRA, SEZ6L, SGCE, and SNRPN). Further, most of these genes had corresponding reduced expression levels in gastric cancer compared with intestinal metaplasia, including novel hypermethylated genes in gastric cancer (FLI1, GALR1, SGCE, and SNRPN), suggesting that they may regulate neoplastic transformation from non-malignant intestinal metaplasia to cancer. Our data suggest a tumor-suppressor role for FLI1 in gastric cancer, consistent with recently reported data in breast cancer. For the genes with strongest methylation/expression correlation, namely FLI1, the expression was lowest in microsatellite-unstable tumors compared with other gastric cancer molecular subtypes. Importantly, reduced expression of hypermethylated BRINP1 and SGCE was significantly associated with favorable survival in gastric cancer. In summary, we report novel methylation gene targets that may have functional roles in discrete stages of gastric carcinogenesis and may serve as biomarkers for diagnosis and prognosis of gastric cancer.

The C2 Domain and Altered ATP-Binding Loop Phosphorylation at Ser359 Mediate the Redox-Dependent Increase in Protein Kinase C-δ Activity

ABSTRACT The diverse roles of protein kinase C-δ (PKCδ) in cellular growth, survival, and injury have been attributed to stimulus-specific differences in PKCδ signaling responses. PKCδ exerts membrane-delimited actions in cells activated by agonists that stimulate phosphoinositide hydrolysis. PKCδ is released from membranes as a Tyr313-phosphorylated enzyme that displays a high level of lipid-independent activity and altered substrate specificity during oxidative stress. This study identifies an interaction between PKCδs Tyr313-phosphorylated hinge region and its phosphotyrosine-binding C2 domain that controls PKCδs enzymology indirectly by decreasing phosphorylation in the kinase domain ATP-positioning loop at Ser359. We show that wild-type (WT) PKCδ displays a strong preference for substrates with serine as the phosphoacceptor residue at the active site when it harbors phosphomimetic or bulky substitutions at Ser359. In contrast, PKCδ-S359A displays lipid-independent activity toward substrates with either a serine or threonine as the phosphoacceptor residue. Additional studies in cardiomyocytes show that oxidative stress decreases Ser359 phosphorylation on native PKCδ and that PKCδ-S359A overexpression increases basal levels of phosphorylation on substrates with both phosphoacceptor site serine and threonine residues. Collectively, these studies identify a C2 domain-pTyr313 docking interaction that controls ATP-positioning loop phosphorylation as a novel, dynamically regulated, and physiologically relevant structural determinant of PKCδ catalytic activity.

Arsenic trioxide suppresses paclitaxel-induced mitotic arrest

Objectives:  To understand if there exists a functional interaction between arsenic trioxide and paclitaxel in vitro.

Evaluation of Fetuses in the Preventive IVIG Therapy for Congenital Heart Block (PITCH) study

OBJECTIVE The recurrence rate of anti-SSA/Ro-associated congenital heart block (CHB) is 17%. Sustained reversal of third-degree block has never been achieved. Based on potential reduction of maternal autoantibody titers as well as fetal inflammatory responses, intravenous immunoglobulin (IVIG) was evaluated as preventive therapy for CHB. METHODS A multicenter, prospective, open-label study based on Simons 2-stage optimal design was initiated. Enrollment criteria included the presence of anti-SSA/Ro antibodies in the mother, birth of a previous child with CHB/neonatal lupus rash, current treatment with < or = 20 mg/day of prednisone, and <12 weeks pregnant. IVIG (400 mg/kg) was given every 3 weeks from week 12 to week 24 of gestation. The primary outcome was the development of second-degree or third-degree CHB. RESULTS Twenty mothers completed the IVIG protocol before the predetermined stopping rule of 3 cases of advanced CHB in the study was reached. CHB was detected at 19, 20, and 25 weeks; none of the cases occurred following the finding of an abnormal PR interval on fetal Doppler monitoring. One of these mothers had 2 previous children with CHB. One child without CHB developed a transient rash consistent with neonatal lupus. Sixteen children had no manifestations of neonatal lupus at birth. No significant changes in maternal titers of antibody to SSA/Ro, SSB/La, or Ro 52 kd were detected over the course of therapy or at delivery. There were no safety issues. CONCLUSION This study establishes the safety of IVIG and the feasibility of recruiting pregnant women who have previously had a child with CHB. However, IVIG at low doses consistent with replacement does not prevent the recurrence of CHB or reduce maternal antibody titers.

Variability in sensitivity to arsenite does not correlate with arsenic accumulation rate in normal human lymphoblasts.

Arsenic is a common environmental contaminant of our air, water and food, but not every individual who drinks arsenic-contaminated water shows clinical signs of toxicity. Large inter-individual variations are also found in arsenite-induced aneuploidy, chromosome aberrations and sister chromatid exchanges in peripheral blood lymphocytes from different human donors. Lymphoblasts are virally immortalized lymphocytes that retain most of the properties of lymphocytes. Individual lymphoblast cell lines retained their arsenite sensitivity after cryopreservation and subsequent revival. We measured the accumulation of 73[As]-arsenite into lymphoblast lines derived from 11 normal individuals. Arsenite accumulation rate varied 6.3 fold between the slowest and the fastest subjects. Assays in 14 lymphoblast lines showed variability to the toxic effects of arsenite, as measured by growth inhibition. Lymphoblast lines also vary with regard to their growth rates, but there is no relationship between growth rate and arsenite sensitivity. Surprisingly, we also found no correlation between arsenite accumulation rate and cellular sensitivity to growth inhibition, suggesting that the arsenite accumulation rate may not be the main determinant of cellular sensitivity to arsenic. We were also unable to detect evidence for a human homolog for the yeast arsenite efflux gene ACR3, using RT-PCR.