Protein Z, protein S levels are lower in patients with thrombophilia and subsequent pregnancy complications.

OBJECTIVE: We posit that low levels of protein S (PS) and protein Z (PZ) contribute to adverse pregnancy outcome (APO). PATIENTS: We evaluated 103 women with subsequent normal pregnancy outcome (NPO), 106 women with APO, and 20 women with thrombophilia (TP). METHODS: We compared first trimester (1st TRI) PZ levels in 103 women with NPO, 106 women with APO, and in 20 women with TP. We compared plasma levels of PZ and free PS antigen during the second (2nd TRI) and third trimesters (3rd TRI) of pregnancy in 51 women with APO and 51 matched women with NPO. RESULTS: The mean 1st TRI PZ level was significantly lower among patients with APO, compared to pregnant controls (1.81 +/- 0.7 vs. 2.21 +/- 0.8 microg mL(-1), respectively, P < 0.001). Of patients with known TP, those with APO had a tendency for lower mean PZ levels compared to those TP women with NPO (1.5 +/- 0.6 vs. 2.3 +/- 0.9 microg mL(-1), respectively, P < 0.0631). There was a significant decrease in the PZ levels in patients with APO compared to NPO (2nd TRI 1.5 +/- 0.4 vs. 2.0 +/- 0.5 microg mL(-1), P < 0.0001; and 3rd TRI 1.6 +/- 0.5 vs. 1.9 +/- 0.5 microg mL(-1), P < 0.0002). Protein S levels were significantly lower in the 2nd and 3rd TRIs among patients with APO compared to patients with NPO (2nd TRI 34.4 +/- 11.8% vs. 38.9 +/- 10.3%, P < 0.05, respectively; and 3rd TRI 27.5 +/- 8.4 vs. 31.2 +/- 7.4, P < 0.025, respectively). CONCLUSIONS: We posit that decreased PZ and PS levels are additional risk factors for APO.

The use of coagulation activation markers (soluble fibrin polymer, TpP, prothrombin fragment 1.2, thrombin-antithrombin, and D-dimer) in the assessment of hypercoagulability in patients with inherited and acquired prothrombotic disorders.

A total of 260 consecutive patients, referred for hypercoagulable assessment, was included in this study. Four coagulation activation markers were utilized to assess these patients [enzyme-linked immunosorbent assays for soluble fibrin polymer (TpP), prothrombin fragment 1.2, thrombin-antithrombin complex, and D-dimer]. The mean levels of the activation markers directly correlated with the number of hypercoagulable abnormalities. The percentage of patients with increased TpP levels for each group was lower than the other activation markers. The findings indicate that activation markers reflect the number of underlying thrombophilic abnormalities. Our data suggest that there is a utility in performing a panel of coagulation activation markers to assess the thrombotic risk. The measurement of soluble fibrin polymer may be more reflective of an impending vascular event.

Thrombophilia and pregnancy: review of the literature and some original data.

The association of thrombophilia with pregnancy complications has received increasing attention. It is now apparent that thrombophilia is responsible for a large number of the serious complications of pregnancy such as venous thrombosis, pulmonary embolism, fetal loss, pregnancy loss, intrauterine fetal demise, and preeclampsia. The inherited thrombophilia abnormalities, factor V Leiden mutation, prothrombin gene mutation 20210A, and antithrombin III, protein C, and protein S deficiency, and the acquired disorders, the anticardiolipin syndrome and lupus inhibitor, are responsible for a large share of the incidences of premature termination of pregnancy and many of the above complications. The normal physiology of pregnancy may be prothrombotic, with evidence for increased markers of activated coagulation and coagulation factors. There is a decrease in protein S and resistance to activated protein C occurs in a significant number of pregnancies in the absence of the factor V Leiden mutation. In the following article, we review some of the major studies that have correlated the thrombophilia and other acquired disorders that adversely impact pregnancies.

The use of thrombus precursor protein, D-dimer, prothrombin fragment 1.2, and thrombin antithrombin in the exclusion of proximal deep vein thrombosis and pulmonary embolism.

We examined various nonSTAT commercially available coagulation activation markers in an attempt to help diagnose or exclude the often subtle clinical presentations of proximal deep vein thrombosis (PDVT) and pulmonary embolism (PE). Fifty-five patients presenting to the Emergency Department were completely assessed. Eleven patients were diagnosed with PDVT, six patients were diagnosed with PE, and three patients were diagnosed with both PDVT and PE. Thrombus precursor protein (TpP) excluded the diagnosis in 19 of the 35 patients negative for PDVT and/or PE, D-Dimer in 15 patients, prothrombin fragment 1.2 in 17 patients, and thrombin-antithrombin (TAT) in 14 patients. Both the TpP and TAT enzyme-linked immunosorbent assay (ELISA) tests had 100% sensitivity and negative predictive value for evaluating PDVT and/or PE. The TpP ELISA had the highest specificity (54%) of all four markers studied.

Ischemic stroke in a young patient with protein C deficiency and prothrombin gene mutation G20210A.

We report a patient who had an ischemic stroke aged 22 years, an inherited type I protein C deficiency and a heterozygous genotype of prothrombin gene 20210A. In view of recent reports of an increased risk for ischemic cerebral vascular disease in patients with the prothrombin 20210A mutation, we suggest that many of the reported cases of ischemic stroke and protein C deficiency may have had additional prothrombotic disorders such as the prothrombin mutation. The current data concerning the magnified risk for stroke in patients with the prothrombin 20210A mutation suggests the need to study all patients with premature stroke for this mutation and the other risk factors for thrombosis. This would include homocysteine, lupus inhibitor, anticardiolipin antibodies, and possibly the natural inhibitors of coagulation. It is possible that patients with the prothrombin 20210A mutation and ischemic cerebral vascular disease would benefit from long-term anticoagulation therapy in a similar way to patients with the antiphospholipid syndrome.

ets-2 regulates cdc2 kinase activity in mammalian cells: coordinated expression of cdc2 and cyclin A.

ets-2 is a member of a family of transcription factors implicated in the regulation of gene expression during cell proliferation, cell differentiation, and development. We report that the ets-2 protein transactivates the promoter of the cdc2 gene which encodes a 34-kDa serine-threonine kinase required for mitotic initiation in mammalian cells. Transactivation occurs via specific interaction with multiple ets binding sites in the 5' flanking region of the gene. In BALB/c3T3 rodent fibroblasts constitutively expressing ets-2 and cultured in either 10 or 0.5% serum, cdc2 expression and its associated histone H1 kinase activity are increased, compared to control cells. Such increased activity correlates with elevated levels of cyclin A but not cyclin B1. Furthermore, ets-2-transfected, but not parental, BALB/c3T3 cells, grow under low serum conditions, albeit at a reduced rate. These data demonstrate that ets-2 plays a direct role in the regulation of cdc2 expression and raise the possibility that ets-2 participates in the coordinated regulation of cdc2 cyclin A expression which is essential for the modulation of cdc2-regulated processes.

Negative regulation of p120GAP GTPase promoting activity by p210bcr/abl: implication for RAS-dependent Philadelphia chromosome positive cell growth.

The p210bcr/abl tyrosine kinase appears to be responsible for initiating and maintaining the leukemic phenotype in chronic myelogenous leukemia (CML) patients. p21ras-p120GAP interactions play a central role in transducing mitogenic signals. Therefore, we investigated whether p21ras and p120GAP are regulated by p210bcr/abl, and whether this activation is functionally significant for CML cell proliferation. We report that transient expression of p210bcr/abl in fibroblast-like cells induces simultaneous activation of p21ras and inhibition of GTPase-promoting activity of p120GAP, and confirm these data showing that downregulation of p210bcr/abl expression in CML cells with bcr/abl antisense oligodeoxynucleotides induces both inhibition of p21ras activation and stimulation of GTPase-promoting activity of p120GAP. Tyrosine phosphorylation of two p120GAP-associated proteins, p190 and p62, which may affect p120GAP activity, also depends on p210bcr/abl tyrosine kinase expression. Direct dependence of these effects on the kinase activity is proven in experiments in which expression of c-MYB protein in fibroblast-like cells or downregulation of c-MYB expression resulting in analogous inhibition of CML cell proliferation does not result in the same changes. Use of specific antisense oligodeoxynucleotides to downregulate p21ras expression revealed a requirement for functional p21ras in the proliferation of Philadelphia chromosome-positive CML primary cells. Thus, the p210bcr/abl-dependent regulation of p120GAP activity is responsible, in part, for the maintenance of p21ras in the active GTP-bound form, a crucial requirement for CML cell proliferation.

Regulation of the expression of the hematopoietic stem cell antigen CD34: role of c-myb.

The CD34 antigen defines a subset of hematopoietic progenitor cells with self-renewal capacity and the ability to reconstitute hematopoiesis in irradiated primates and marrow-ablated humans, but its function remains unknown. The c-myb protooncogene plays a fundamental role in hematopoiesis, most likely via its transcriptional regulator function. We report that c-myb protein transactivates the CD34 promoter via specific interaction with multiple Myb binding sites in the 5' flanking region of the gene and induces expression of the endogenous CD34 mRNA in rodent fibroblasts. Also, constitutive expression of c-myb in CD34-negative human glioblastoma cells induces expression of CD34 mRNA and synthesis of the surface membrane antigen. These data directly demonstrate that c-myb regulates the expression of the hematopoietic stem cell antigen CD34 and raise the possibility that c-myb regulates hematopoiesis inducing a cascade of differentiation-related events.

Regulation of proliferation and cytokine expression of bone marrow fibroblasts: role of c-myb.

The c-myb protooncogene plays a major role in regulating the process of in vitro and in vivo hematopoiesis via its activity as transcriptional regulator in hematopoietic progenitor cells. Since the bone marrow microenvironment appears to regulate in vivo hematopoiesis by maintaining the growth of multipotent progenitors via secretion of specific cytokines, we asked whether c-myb is also required for the proliferation of and/or cytokine production by stromal cells that generate fibroblast-like colonies (fibroblast colony-forming units [CFU-F]). Using the reverse transcriptase polymerase chain reaction technique, we detected low levels of c-myb mRNA transcripts in human normal bone marrow fibroblasts. Treatment of these cells with c-myb antisense oligodeoxynucleotides caused downregulation of c-myb expression, decreased in the number of marrow CFU-F colonies (approximately 54% inhibition) and in the cell number within residual colonies (approximately 80%), and downregulation of granulocyte/macrophage colony-stimulating factor (GM-CSF) and stem cell factor (SCF) mRNA expression. Transfection of T98G glioblastoma cells, in which expression of c-myb, GM-CSF, and SCF mRNAs is undetectable or barely detectable, with a plasmid containing a full-length c-myb cDNA under the control of the SV40 promoter induced the expression of biologically active SCF and GM-CSF in these cells. Regulation of GM-CSF expression by c-myb was due in part to transactivation of the GM-CSF promoter. These results indicate that, in addition to regulating hematopoietic cell proliferation, c-myb is also required for proliferation of and cytokines synthesis by bone marrow fibroblasts.

c-myb transactivates cdc2 expression via Myb binding sites in the 5'-flanking region of the human cdc2 gene.

The c-myb protooncogene is preferentially expressed in hematopoietic cells and is required for cell cycle progression at the G1/S boundary. Because c-myb encodes a transcriptional activator that functions via DNA binding, it is likely that c-myb exerts its biological activity by regulating the transcription of genes required for DNA synthesis and cell cycle progression. One such gene, cdc2, encodes a 34-kDa serine-threonine kinase that appears to be required for G1/S transition in normal human T-lymphocytes. To determine whether c-myb is a transcriptional regulator of cdc2 expression, we subcloned a segment of a cdc2 human genomic clone containing extensive 5'-flanking sequences and part of the first exon. Sequence analysis revealed the presence of two closely spaced Myb binding sites that interact with bacterially synthesized Myb protein within a region extending from nucleotides -410 to -392 upstream of the transcription initiation site. A 465-base pair segment of 5'-flanking sequence containing these sites was linked to the CAT gene and had promoter activity in rodent fibroblasts. Cotransfection of this construct with a full-length human c-myb cDNA driven by the early simian virus 40 promoter resulted in a 6-8-fold enhancement of CAT activity that was abrogated by mutations in the Myb binding sites. These data suggest that c-myb participates in the regulation of cell cycle progression by activating the expression of the cdc2 gene.

A new growth-regulated complementary DNA with the sequence of a putative trans-activating factor.

A new complementary DNA (cDNA) clone has been isolated by differential screening of a cDNA library. The cognate RNA of this clone, called SC1, is growth regulated in human, mouse, and hamster cell lines. Its kinetics of growth regulation (time of increase in mRNA levels, sensitivity to cycloheximide, behavior in G1-specific temperature-sensitive mutants) classify the SC1 gene as a late growth-regulated gene, like the histone genes and the genes coding for the proteins of the DNA synthesis apparatus. By run-on assay, there is a modest increase in transcriptional rates after serum stimulation, which is not sufficient to explain the sharp increase in mRNA levels. The SC1 gene localizes to human chromosome 6p21-22. In bacteria, the SC1 cDNA clone makes a protein of Mr 39,000, in agreement with the putative reading frame. The amino acid sequence derived from the cDNA sequence indicates a previously unknown gene with a domain strongly suggestive of a trans-activating domain. The SC1 gene can be considered as coding for a possible new trans-activating factor that could play an important role in the transcription of genes required for the later stages of cell cycle progression.

Characterization of an enhancer-like structure in the promoter region of the proliferating cell nuclear antigen (PCNA) gene.

The steady-state mRNA levels of the proliferating cell nuclear antigen (PCNA) gene depend on the length of its promoter. A promoter extending from the HpaII restriction site at -210 from the cap site to the cap site itself is very active, while a -45 promoter (AatII restriction site) is very weak. We now show that the sequences between -73 and -45 of the human PCNA promoter contain an enhancer-like sequence that markedly increases the levels of PCNA mRNA. This sequence has characteristics of an enhancer, having an enhancing function also when placed away from the native position in the 5' flanking sequence. The increase in mRNA levels that occurs after serum stimulation, however, is independent of the enhancer. Synthetic promoters were also constructed containing mutations in the -73 to -45 sequence and these mutants completely lost their ability to drive the transcription of a heterologous cDNA. Nuclear proteins were shown to bind to this sequence, both by gel shift and by methylation interference analysis. We conclude that the levels of PCNA mRNA are controlled, in part, by a structure located in the 5' flanking sequence of the gene, but that this enhancer-like structure does not play a role in the serum regulation of the mRNA levels.