African American patients with Multiple Sclerosis (MS) have higher proportions of CD19+ and CD20+ B-cell lineage cells in their cerebrospinal fluid than White MS patients

OBJECTIVES

To compare proportions of B-cell lineage CD19+ and CD20+ cells in CSF of African-American (AA) and White (W) patients with MS.

BACKGROUND

AA MS patients are more likely to have oligoclonal bands in CSF, higher IgG index in CSF, and higher circulating plasmablasts in blood than W MS patients. It is unknown whether the proportion of B-cells in CSF differs between AA and W patients in MS.

METHODS

Demographics, disease-related information, treatment history were retrospectively collected on patients with MS who self-identified as AA or W and underwent flow cytometry of CSF during diagnostic work-up. Proportion of B-lymphocytes, T-lymphocytes, NK cells, monocytes, and plasma cells were analyzed with flow cytometry.

RESULTS

20 AA and 56 W MS patients fulfilled our inclusion criteria. The groups had similar demographics, CSF cell counts, protein and glucose CSF concentrations, and oligoclonal band number. IgG index was higher in AA compared to W (1.08 vs. 0.85, p = 0.031). AA had higher proportions of CD19+ (5.46 % AA vs. 2.26 % W, p = 0.006) and CD20+ (4.64 % AA vs. 1.91 % W, p = 0.004) cells but did not significantly differ in proportion of CD4+, CD8+, CD38+ bright B-cells, NK cells and monocytes.

CONCLUSIONS

B-cells are overrepresented in the CSF of African American patients with MS relative to Whites.

Haplodeficiency of the 9p21 tumor suppressor locus causes myeloid disorders driven by the bone marrow microenvironment

The chromosome 9p21 locus comprises several tumor suppressor genes including MTAP, CDKN2A, and CDKN2B, and its homo- or heterozygous deletion is associated with reduced survival in multiple cancer types. We report that mice with germ line monoallelic deletion or induced biallelic deletion of the 9p21-syntenic locus (9p21s) developed a fatal myelodysplastic syndrome/myeloproliferative neoplasm (MDS/MPN)-like disease associated with aberrant trabecular bone formation and/or fibrosis in the bone marrow (BM). Reciprocal BM transfers and conditional targeting of 9p21s suggested that the disease originates in the BM stroma. Single-cell analysis of 9p21s-deficient BM stroma revealed the expansion of chondrocyte and osteogenic precursors, reflected in increased osteogenic differentiation in vitro. It also showed reduced expression of factors maintaining hematopoietic stem/progenitor cells, including Cxcl12. Accordingly, 9p21s-deficient mice showed reduced levels of circulating Cxcl12 and concomitant upregulation of the profibrotic chemokine Cxcl13 and the osteogenesis- and fibrosis-related multifunctional glycoprotein osteopontin/Spp1. Our study highlights the potential of mutations in the BM microenvironment to drive MDS/MPN-like disease.

Loss of FBXO31-mediated degradation of DUSP6 dysregulates ERK and PI3K-AKT signaling and promotes prostate tumorigenesis

FBXO31 is the substrate receptor of one of many CUL1-RING ubiquitin ligase (CRL1) complexes. Here, we show that low FBXO31 mRNA levels are associated with high pre-operative prostate-specific antigen (PSA) levels and Gleason grade in human prostate cancer. Mechanistically, the ubiquitin ligase CRL1FBXO31 promotes the ubiquitylation-mediated degradation of DUSP6, a dual specificity phosphatase that dephosphorylates and inactivates the extracellular-signal-regulated kinase-1 and -2 (ERK1/2). Depletion of FBXO31 stabilizes DUSP6, suppresses ERK signaling, and activates the PI3K-AKT signaling cascade. Moreover, deletion of FBXO31 promotes tumor development in a mouse orthotopic model of prostate cancer. Treatment with BCI, a small molecule inhibitor of DUSP6, suppresses AKT activation and prevents tumor formation, suggesting that the FBXO31 tumor suppressor activity is dependent on DUSP6. Taken together, our studies highlight the relevance of the FBXO31-DUSP6 axis in the regulation of ERK- and PI3K-AKT-mediated signaling pathways, as well as its therapeutic potential in prostate cancer.

CRL4AMBRA1 is a master regulator of D-type cyclins

D-type cyclins are central regulators of the cell division cycle and are among the most frequently deregulated therapeutic targets in human cancer¹, but the mechanisms that regulate their turnover are still being debated^2,3. Here, by combining biochemical and genetics studies in somatic cells, we identify CRL4^AMBRA1 (also known as CRL4^DCAF3) as the ubiquitin ligase that targets all three D-type cyclins for degradation. During development, loss of Ambra1 induces the accumulation of D-type cyclins and retinoblastoma (RB) hyperphosphorylation and hyperproliferation, and results in defects of the nervous system that are reduced by treating pregnant mice with the FDA-approved CDK4 and CDK6 (CDK4/6) inhibitor abemaciclib. Moreover, AMBRA1 acts as a tumour suppressor in mouse models and low AMBRA1 mRNA levels are predictive of poor survival in cancer patients. Cancer hotspot mutations in D-type cyclins abrogate their binding to AMBRA1 and induce their stabilization. Finally, a whole-genome, CRISPR-Cas9 screen identified AMBRA1 as a regulator of the response to CDK4/6 inhibition. Loss of AMBRA1 reduces sensitivity to CDK4/6 inhibitors by promoting the formation of complexes of D-type cyclins with CDK2. Collectively, our results reveal the molecular mechanism that controls the stability of D-type cyclins during cell-cycle progression, in development and in human cancer, and implicate AMBRA1 as a critical regulator of the RB pathway.

Epigenetic silencing of the ubiquitin ligase subunit FBXL7 impairs c-SRC degradation and promotes epithelial-to-mesenchymal transition and metastasis

Epigenetic plasticity is a pivotal factor that drives metastasis. Here, we show that the promoter of the gene that encodes the ubiquitin ligase subunit FBXL7 is hypermethylated in advanced prostate and pancreatic cancers, correlating with decreased FBXL7 mRNA and protein levels. Low FBXL7 mRNA levels are predictive of poor survival in patients with pancreatic and prostatic cancers. FBXL7 mediates the ubiquitylation and proteasomal degradation of active c-SRC after its phosphorylation at Ser 104. The DNA-demethylating agent decitabine recovers FBXL7 expression and limits epithelial-to-mesenchymal transition and cell invasion in a c-SRC-dependent manner. In vivo, FBXL7-depleted cancer cells form tumours with a high metastatic burden. Silencing of c-SRC or treatment with the c-SRC inhibitor dasatinib together with FBXL7 depletion prevents metastases. Furthermore, decitabine reduces metastases derived from prostate and pancreatic cancer cells in a FBXL7-dependent manner. Collectively, this research implicates FBXL7 as a metastasis-suppressor gene and suggests therapeutic strategies to counteract metastatic dissemination of pancreatic and prostatic cancer cells.

IFNγ-Induced IFIT5 Promotes Epithelial-to-Mesenchymal Transition in Prostate Cancer via miRNA Processing

IFNγ, a potent cytokine known to modulate tumor immunity and tumoricidal effects, is highly elevated in patients with prostate cancer after radiation. In this study, we demonstrate that IFNγ can induce epithelial-to-mesenchymal transition (EMT) in prostate cancer cells via the JAK-STAT signaling pathway, leading to the transcription of IFN-stimulated genes (ISG) such as IFN-induced tetratricopeptide repeat 5 (IFIT5). We unveil a new function of IFIT5 complex in degrading precursor miRNAs (pre-miRNA) that includes pre-miR-363 from the miR-106a-363 cluster as well as pre-miR-101 and pre-miR-128, who share a similar 5'-end structure with pre-miR-363. These suppressive miRNAs exerted a similar function by targeting EMT transcription factors in prostate cancer cells. Depletion of IFIT5 decreased IFNγ-induced cell invasiveness in vitro and lung metastasis in vivo. IFIT5 was highly elevated in high-grade prostate cancer and its expression inversely correlated with these suppressive miRNAs. Altogether, this study unveils a prometastatic role of the IFNγ pathway via a new mechanism of action, which raises concerns about its clinical application.Significance: A unique IFIT5-XRN1 complex involved in the turnover of specific tumor suppressive microRNAs is the underlying mechanism of IFNγ-induced epithelial-to-mesenchymal transition in prostate cancer.See related commentary by Liu and Gao, p. 1032.

Low Prevalence of the Factor V Leiden Mutation Among “Severe” Hemophiliacs with a “Milder” Bleeding Diathesis

Patients with hemophilia A and B and factor levels less than 1 percent of normal bleed frequently with an average number of spontaneous bleeding episodes of 20–30 or more. However there are patients with equally low levels of factor VIII or factor IX who bleed once or twice per year or not at all. To examine whether the presence of a hereditary defect predisposing to hypercoagulability might play a role in amelio rating the hemorrhagic tendency in these so-called “mild severe” hemophiliacs, we determined the prevalence of prothrombotic defects in 17 patients with hemophilia A and four patients with hemophilia B selected from 295 and 76 individuals with these disorders, respectively, followed at a large Italian hemophilia center. We tested for the presence of the Factor V Leiden mutation by PCR-amplifying a fragment of the factor V gene which contains the mutation site and then digesting the product with the restriction enzyme Mnll. None of the patients with hemophilia A and only one patient with hemophilia B was heterozygous for Factor V Leiden. None of the 21 patients had hereditary deficiencies of antithrombin III, protein C, or protein S. Our results indicate that the milder bleeding diathesis that is occasionally seen among Italian hemophiliacs with factor levels that are less than 1 percent cannot be explained by the concomitant expression of a known prothrombotic defect.

Are Capillary Whole Blood Coagulation Monitors Suitable for the Control of Oral Anticoagulant Treatment by the International Normalized Ratio?

The 512 Coagulation Monitor is a portable coagulation photometer that uses disposable cartridges containing a lyophilized rabbit brain thromboplastin to measure the PT for capillary whole blood. It has been proposed as a suitable system for patient self monitoring at home, but its performance has never been thoroughly assessed for results expressed as International Normalized Ratio (INR). In particular, there is no available information about the adequacy of the WHO calibration model with the Monitor. The aims of the study were to determine the International Sensitivity Index (ISI) against the secondary International Reference Preparation for rabbit thromboplastin and to assess the precision of the INR. The study demonstrates that the Monitor can be calibrated with the WHO model, because log-transformed PTs for patients stabilized on oral anticoagulants and normal individuals are linearly related and because the same orthogonal regression line describes patient and normal data points adequately. However, the ISI calculated in this study (2.715) is higher than that adopted by the manufacturer (2.036). The between-assay reproducibility of the Monitor is acceptable (CV = 9.7%) with results expressed in seconds, but become unacceptably poor when the results are converted into INR (CV = 18.8%) because of the high ISI value of the thromboplastin used. We think that the Monitor might be suitable for monitoring oral anticoagulant therapy if the manufacturer would provide a more sensitive thromboplastin in the cartridges.

Effects of Hirudin on Activated Partial Thromboplastin Time Determined with Ten Different Reagents

Hirudin prolongs the APTT when added to normal plasma and the extent of prolongation depends on the type of reagent used. The aim of this study was to compare the dose-response curves of 10 widely used APTT reagents for linearity and parallelism. On each of 10 working days a normal pooled plasma was mixed with increasing amounts of recombinant hirudin (HBW023) ranging from 0 to 5 μg/ml and tested for APTT by photo optical coagulometer. Within each working day, clotting times were measured in duplicate and the order of testing with each reagent was changed every day. Results were expressed as ratios of clotting times with hirudin to clotting times without hirudin, and the values plotted against the hirudin concentration on a log-log scale. The dose-response curves for all reagents were linear over 0.3–1.2 μg/ml. The reagent-related slopes ranged from 0.225 ± 0.003 to 0.303 ± 0.003 (mean ± SE) and were significantly different. Precision studies indicated that the least sensitive reagent was also the least precise. These findings indicate that the clotting time values obtained for patients treated with hirudin will vary depending on the APTT reagent used.

Intravascular large B-cell lymphoma with multi-organ failure presenting as a pancreatic mass: a case with atypical presentation and definite diagnosis postmortem

Intravascular large B-cell lymphoma (IVLBCL) is a very rare extra nodal lymphoma that tends to proliferate within small blood vessels, particularly capillaries and postcapillary venules while sparing the organ parenchyma. The cause of its affinity for the vascular bed remains unknown. Because of its rarity and unremarkable clinical presentation, a timely diagnosis of IVLBCL is very challenging. Here, we describe a case of IVLBCL presenting as pancreatic mass that was ultimately diagnosed at autopsy. A 71-year-old Caucasian female presented with a 3-month history of fatigue, abdominal pain, and weight loss. She was referred to the emergency room with a new diagnosis of portal vein thrombosis and lactic acidosis. During her hospital course she was found to have a 1.9 × 1.8 cm lesion in the pancreatic tail on imaging; The cytologic specimen on the mass showed a high-grade lymphoma. A bone marrow biopsy showed no involvement. The patient’s condition rapidly deteriorated and she, later, died due to multi-organ failure. An autopsy revealed diffuse intravascular invasion in multiple organs by the lymphoma cells. Based on our literature review—and to the best of our knowledge—there are virtually no reports describing the presentation of this lymphoma with a discernible tissue mass and associated multi-organ failure. The immunophenotypic studies performed revealed de novo CD5+ intravascular large B-cell lymphoma, which is known to be aggressive with very poor prognosis. Although it is a very rare lymphoma, it should be considered as a potential cause of multi-organ failure when no other cause has been identified. A prompt tissue diagnosis, appropriate high-dose chemotherapy and stem cell transplantation remain the only viable alternative to achieve some kind of remission.

Mitochondrial Dysfunction: A Novel Potential Driver of Epithelial-to-Mesenchymal Transition in Cancer

Epithelial-to-mesenchymal transition (EMT) allows epithelial cancer cells to assume mesenchymal features, endowing them with enhanced motility and invasiveness, thus enabling cancer dissemination and metastatic spread. The induction of EMT is orchestrated by EMT-inducing transcription factors that switch on the expression of “mesenchymal” genes and switch off the expression of “epithelial” genes. Mitochondrial dysfunction is a hallmark of cancer and has been associated with progression to a metastatic and drug-resistant phenotype. The mechanistic link between metastasis and mitochondrial dysfunction is gradually emerging. The discovery that mitochondrial dysfunction owing to deregulated mitophagy, depletion of the mitochondrial genome (mitochondrial DNA) or mutations in Krebs’ cycle enzymes, such as succinate dehydrogenase, fumarate hydratase, and isocitrate dehydrogenase, activate the EMT gene signature has provided evidence that mitochondrial dysfunction and EMT are interconnected. In this review, we provide an overview of the current knowledge on the role of different types of mitochondrial dysfunction in inducing EMT in cancer cells. We place emphasis on recent advances in the identification of signaling components in the mito-nuclear communication network initiated by dysfunctional mitochondria that promote cellular remodeling and EMT activation in cancer cells.

Rapid and robust reversion to essential thrombocythemia on treatment with Decitabine in a case of hydroxyurea-induced t-MDS/AML

Rapid remission of MDS/AML may be induced with Decitabine; however, significant megakaryocyte expansion and subsequent thrombocytosis may occur. Decitabine‐mediated reversion of the MDS to benign ET via hypomethylation of JAK/STAT pathway repressors is one potential mechanism to explain this observed phenomenon.

Mitochondrial DNA depletion sensitizes cancer cells to PARP inhibitors by translational and post-translational repression of BRCA2

Previous studies have shown that pharmacologic inhibition of poly (ADP-ribose) polymerase (PARP), a nuclear protein that is crucial in signaling single-strand DNA breaks, is synthetically lethal to cancer cells from patients with genetic deficiency in the DNA repair proteins BRCA1 and BRCA2. Herein, we demonstrate that depletion of the mitochondrial genome (mtDNA) in breast, prostate and thyroid transformed cells resulted in elevated steady-state cytosolic calcium concentration and activation of calcineurin/PI3-kinase/AKT signaling leading to upregulation of miR-1245 and the ubiquitin ligase Skp2, two potent negative regulators of the tumor suppressor protein BRCA2, thus resulting in BRCA2 protein depletion, severe reduction in homologous recombination (HR) and increased sensitivity to the PARP inhibitor rucaparib. Treatment of mtDNA-depleted cells with the PI3-kinase inhibitor LY294002, the calmodulin antagonist W-7, the calcineurin inhibitor FK506, the calcium chelator BAPTA-AM, or suppression of AKT activity by AKT small-interfering RNA (siRNA) enhanced BRCA2 protein levels as well as HR. Decreasing the intracellular calcium levels using BAPTA, or direct reconstitution of BRCA2 protein levels either by recombinant expression or by small molecule inhibition of both Skp2 and miR-1245 restored sensitivity to rucaparib to wild-type levels. Furthermore, by studying prostate tissue specimens from prostate carcinoma patients we found a direct correlation between the presence of mtDNA large deletions and loss of BRCA2 protein in vivo, suggesting that mtDNA status may serve as a marker to predict therapeutic efficacy to PARP inhibitors. In summary, our results uncover a novel mechanism by which mtDNA depletion restrains HR, and highlight the role of mtDNA in regulating sensitivity to PARP inhibitors in transformed cells.

Bone marrow uptake of ferumoxytol: a preliminary study in healthy human subjects

PURPOSE

To characterize the uptake and elimination of ferumoxytol, an ultrasmall superparamagnetic iron oxide (USPIO) agent, in bone marrow of healthy human subjects.

MATERIALS AND METHODS

Four men and two postmenopausal women, aged 22 to 57 years, were prospectively included. Simultaneous fat, water, and T2* mapping of the proximal femora was performed at 1.5 Tesla using a three-dimensional multiple gradient echo sequence. After baseline imaging, ferumoxytol (Feraheme/Rienso) was injected intravenously at a dose of 5 mg Fe/kg body weight. Imaging was repeated at 3 days, 1 month, 3 months, and 5 months after administration.

RESULTS

Imaging at 3 days revealed large increases in R2* ( =1/T2*) in hematopoietic marrow and lower average responses in fatty marrow, consistent with macrophage-specific uptake. However, certain regions of the diaphysis exhibited substantial R2* enhancement despite having very high fat content. This suggests the persistence of residual marrow stroma following adipose conversion, and may reflect the ability of diaphyseal marrow to adapt dynamically to fluctuating demand for hematopoiesis. Follow-up imaging demonstrated almost complete R2* recovery within 3 months.

CONCLUSION

The observed R2* enhancement characteristics support applications for ferumoxytol in distinguishing normal or hypercellular marrow from neoplasms, infection and inflammation. Further studies are warranted in specific patient populations.

Stress-related mitochondrial components and mitochondrial genome as targets of anticancer therapy

In addition to their role as cell powerhouse mitochondria are key organelles in the processes deciding about cell life or death that are crucial for tumor cell growth and survival, as well as for tumor cell ability to metastasize. Alterations in mitochondrial structure and functions have long been observed in cancer cells, thus targeting mitochondria as an anticancer therapeutic strategy has gained momentum recently. We will review the achievements and perspectives in the elucidation of the molecular basis for developing mitochondrial-targeted compounds as potential anticancer agents with special attention to mitochondrial DNA mutations and mitochondrial dysfunction. Molecules/agents candidate to affect mitochondrial metabolism in cancer cells will be dealt with, with a particular focus on approaches targeting defects in the mitochondrial genome.

Selective targeting of the mTORC1/2 protein kinase complexes leads to antileukemic effects in vitro and in vivo

The BCR/ABL tyrosine kinase promotes leukemogenesis through activation of several targets that include the phosphoinositide 3-kinase (PI3K). Tyrosine kinase inhibitors (TKIs), which target BCR/ABL, induce striking clinical responses. However, therapy with TKIs is associated with limitations such as drug intolerance, inability to universally eradicate the disease and emergence of BCR/ABL drug-resistant mutants. To overcome these limitations, we tested whether inhibition of the PI3K/target of rapamycin (mTOR) signaling pathway has antileukemic effect in primary hematopoietic stem cells and BA/F3 cells expressing the BCR/ABL oncoprotein. We determined that dual inhibition of PI3K/mTOR causes growth arrest and apoptosis leading to profound antileukemic effects both in vitro and in vivo. We also established that pharmacologic inhibition of the mTORC1/mTORC2 complexes is sufficient to cause these antileukemic effects. Our results support the development of inhibitors of the mTORC1/2 complexes for the therapy of leukemias that either express BCR/ABL or display deregulation of the PI3K/mTOR signaling pathway.

Skp2 overexpression is associated with loss of BRCA2 protein in human prostate cancer

BRCA2 (breast cancer 2, early onset) is a tumor suppressor gene that confers increased susceptibility for prostate cancer (PCa). Previous in vitro experiments demonstrated that Skp2, an E3 ubiquitin ligase aberrantly overexpressed in PCa, is involved in the proteolytic degradation of BRCA2 in PCa cells, suggesting that the BRCA2-Skp2 interaction may play a role in prostate tumorigenesis. Herein, we investigated BRCA2 and Skp2 expression during PCa development using a prostate TMA. Although luminal and basal benign prostate epithelium exhibited moderate to strong nuclear BRCA2 immunostaining, the intensity and number of positive nuclei decreased significantly in high-grade prostatic intraepithelial neoplasia and PCa. Decreased frequency and intensity of nuclear BRCA2 labeling were inversely correlated with Skp2 expression in high-grade prostatic intraepithelial neoplasia and PCa. To functionally assess the effects of BRCA2 and Skp2 expression on prostate malignant transformation, we overexpressed Skp2 in normal immortalized prostate cells. Skp2 overexpression reduced BRCA2 protein and promoted cell growth and migration. A similar phenotype was observed after reduction of BRCA2 protein levels using specific BRCA2 small-interfering RNA. Forced BRCA2 expression in Skp2-overexpressing stable transfectants inhibited the migratory and growth properties by >60%. These results show that loss of BRCA2 expression during prostate tumor development is strongly correlated with both migratory behavior and cancer growth and include Skp2 as a BRCA2 proteolytic partner in vivo.

Aromatase deficiency inhibits the permeability transition in mouse liver mitochondria

Lack of estrogens affects male physiology in a number of ways, including severe changes in liver metabolism that result in lipid accumulation and massive hepatic steatosis. Here we investigated whether estrogen deficiency may alter the functionality and permeability properties of liver mitochondria using, as an experimental model, aromatase knockout (ArKO) male mice, which cannot synthesize endogenous estrogens due to a disruption of the Cyp19 gene. Liver mitochondria isolated from ArKO mice displayed increased activity of the mitochondrial respiratory complex IV compared with wild-type mice and were less prone to undergo cyclosporin A-sensitive mitochondrial permeability transition (MPT) induced by calcium loading. The altered permeability properties of the mitochondrial membranes were not due to changes in reactive oxygen species, ATP levels, or mitochondrial membrane potential but were associated with increased content of the phospholipid cardiolipin, structural component of the mitochondrial membranes and regulator of the MPT pore, and with increased mitochondrial protein levels of Bcl-2 and the adenine nucleotide translocator (ANT), regulator and component of the MPT pore, respectively. Real-time RT-PCR demonstrated increased mRNA levels for Bcl-2 and ANT2 but not for the ANT1 isoform in ArKO livers. Supplementation of 17beta-estradiol retrieved ArKO mice from massive hepatic steatosis and restored mitochondrial permeability properties, cardiolipin, Bcl-2, and ANT2 levels. Overall, our findings demonstrate an important role of estrogens in the modulation of hepatic mitochondrial function and permeability properties in males and suggest that estrogen deficiency may represent a novel positive regulator of Bcl-2 and ANT2 proteins, two inhibitors of MPT occurrence and powerful antiapoptotic molecules.

Segmental tandem triplication of the MLL gene in an intravascular large B-cell lymphoma with multisystem involvement: a comprehensive morphologic, immunophenotypic, cytogenetic, and molecular cytogenetic antemortem study

An association between intravascular large B-cell lymphoma (IVLBCL) and the mixed lineage leukemia (MLL) gene has never been demonstrated. Here, we report an IVLBCL in a 47-year-old Asian man. Morphologically, the atypical lymphoid infiltrate was entirely confined in the lumina of capillaries, small vessels, and sinusoidal space. Within the kidney, the neoplastic lymphoid cells exhibited both the glomerular and peritubular capillary distribution pattern. Conventional cytogenetic analysis from the bone marrow aspirates displayed a complex karyotype, with a notable triple tandem repeat at band segment q22-q25 of chromosome 11. Fluorescence in situ hybridization with an MLL probe set, performed on both interphase cells and metaphase spreads, confirmed the presence of 3 copies of the MLL gene on the derivative chromosome 11. From this finding and 3 other IVLBCL cases reported in the literature, we conclude that MLL may play an important role in the lymphomagenesis of IVLBCL at least in a subset of cases.

Mitochondrial DNA depletion in prostate epithelial cells promotes anoikis resistance and invasion through activation of PI3K/Akt2

Neoplastic transformation of prostate epithelium involves aberrant activation of anti-apoptotic and pro-invasive pathways triggered by multiple poorly understood genetic events. We demonstrated earlier that depletion of mitochondrial DNA (mtDNA) induces prostate cancer progression. Here, using normal prostate epithelial PNT1A cells we demonstrate that mtDNA depletion prevents detachment-induced apoptosis (anoikis) and promotes migratory capabilities onto basement membrane proteins through upregulation of p85 and p110 phosphatidylinositol 3-kinase (PI3K) subunits, which results in Akt2 activation and phosphorylation of downstream substrates GSK3beta, c-Myc, MMP-9, Mdm2, and p53. Pharmacological or genetic PI3K inhibition, siRNA-mediated Akt2 depletion, as well as mtDNA reconstitution were sufficient to restore sensitivity to anoikis and curtail cell migration. Moreover, Akt2 activation induced glucose transporter 1 (GLUT1) expression, glucose uptake, and lactate production, common phenotypic changes seen in neoplastic cells. In keeping with these findings, several prostate carcinoma cell lines displayed reduced mtDNA content and increased PI3K/Akt2 levels when compared to normal PNT1A cells, and Akt2 downregulation prevented their survival, migration and glycolytic metabolism. On a tissue microarray, we also found a statistically significant decrease in mtDNA-encoded cytochrome oxidase I in prostate carcinomas. Taken together, these results provide novel mechanistic evidence supporting the notion that mtDNA mutations may confer survival and migratory advantage to prostate cancer cells through Akt2 signaling.

Mitochondrial DNA depletion reduces PARP-1 levels and promotes progression of the neoplastic phenotype in prostate carcinoma

Mitochondrial dysfunction resulting from mitochondrial DNA (mtDNA) mutations and/or depletion has been correlated with cancer progression and drug resistance. To investigate the role of mtDNA in prostate cancer progression, we used LNCaP and PC-3 prostate carcinoma cells as experimental model. Compared to minimally invasive androgen-dependent LNCaP cells, highly invasive androgen-independent PC-3 cells, as well as androgen-independent DU145 and C4-2 cells, exhibited significantly reduced mtDNA content. In PC-3 cells, reduction of mtDNA was accompanied by decreased mitochondrial membrane potential (ΔΨm), increased migration onto the basement membrane protein laminin-1, reduced chemosensitivity to paclitaxel (IC50=110 nM vs. 22 nM) and decreased expression of poly(ADP-ribose) polymerase (PARP)-1. To investigate the relationship between mtDNA depletion and these phenotypic characteristics, we established mtDNA-depleted LNCaP cells [Rho(−)] by long-term exposure to ethidium bromide or treated wild-type LNCaP cells with a mitochondrial ionophore, carbonyl cyanide m-chlorophenylhydrazone. Both manipulations resulted in ΔΨm loss, acquisition of invasive cytology, increased motility onto laminin-1, reduced sensitivity to paclitaxel (IC50=~100 nM) and ~75% reduction in PARP-1 protein levels, resembling PC-3 cells. Overall, these results provide novel evidence demonstrating that mtDNA depletion in early prostate carcinoma may contribute to the acquisition of a more invasive phenotype that is less sensitive to paclitaxel-induced apoptosis.

Multiparameter flow cytometric analysis reveals low percentage of bone marrow hematogones in myelodysplastic syndromes

Diagnosis of myelodysplastic syndromes (MDS) could be difficult. We explored the usefulness of the enumeration of maturing B-lineage precursors (hematogones) by multiparameter flow cytometric analysis in the diagnosis of MDS in bone marrow (BM) specimens. We evaluated 111 MDS, 120 non-MDS (most with cytopenias; control group 1), and 41 noncytopenic lymphoma staging BM (control group 2) specimens. The percentage of total hematogones was significantly lower in MDS (median, 0%; mean, 0.10%) compared with non-MDS (control group 1, median, 0.38%, and mean, 0.91%; control group 2, median, 0.38%, and mean, 0.60%; P < .0001), as was the percentage of the most immature (stage I) hematogones. Thus, hematogone enumeration may serve as a biomarker to aid in the diagnosis of MDS. Interestingly, the percentage of hematogones was not significantly different between MDS subgroups or patients with MDS with and without chromosomal abnormalities, implying that a defect in maturing B-cell precursors may be an early event in the pathogenesis of MDS.

Loss of BRCA2 promotes prostate cancer cell invasion through up-regulation of matrix metalloproteinase-9

BRCA2 is a multifunctional tumor suppressor protein which plays critical roles in DNA repair, transcription, and cell proliferation, and the loss of which has been linked to the biology of several types of cancers. Here, on prostate adenocarcinoma specimens from 80 patients, we demonstrate that BRCA2 protein is lost in carcinoma cells compared to normal and hyperplastic prostate epithelium. Using highly metastatic prostate cancer PC-3 cells, we show that while BRCA2 depletion by small-interfering RNA promoted migration onto the extracellular matrix proteins fibronectin, laminin, and collagens, as well as invasion through the reconstituted basement membrane matrix Matrigel by more than 140%, recombinant BRCA2 overexpression decreased both phenomena by 57-80% and changed cell morphology from angular and spindle to round and compact. The BRCA2 inhibitory effect on cancer cell migration and invasion resulted from down-regulation of matrix metalloproteinase (MMP)-9 protein levels due to increased MMP-9 proteolysis, and was signaled through inhibition of PI3-kinase/AKT and activation of MAPK/ERK pathway. In BRCA2-overexpressing PC-3 cells, transient transfection with a constitutively active PI3-kinase mutant or treatment with the MAPK/ERK inhibitor PD98059 rescued MMP-9 levels and restored the migratory and invasive capabilities. Consistently, PI3-kinase inhibition with a dominant-negative mutant or MAPK/ERK activation with a gain-of-function mutant reduced MMP-9 levels and prevented migration and invasion in wild-type PC-3 cells. These results provide novel evidence showing that a functional BRCA2 protein may limit the metastatic potential of neoplastic cells by down-regulating MMP-9 production through inhibition of PI3-kinase/AKT and activation of MAPK/ERK, effectively hindering cancer cell migration and invasion.

Constitutive activation of MAPK/ERK inhibits prostate cancer cell proliferation through upregulation of BRCA2

BRCA2 is central to an utterly diverse biological behavior elicited after integrin-mediated normal and prostate cancer cell adhesion to basement membrane (BM) and extracellular matrix (ECM) proteins. Unlike normal cells, adhesive stimuli in cancer cells activate PI 3-kinase/AKT signaling resulting in BRCA2 degradation and unchecked cancer cell proliferation and metastasis. However, the precise mechanisms involved in normal BRCA2 homeostasis are unknown. We investigated ERK and AKT phosphorylation in normal (PNT1A) and cancer (PC-3) prostate cells after adhesion to ECM and the effects upon BRCA2 and cell proliferation. PNT1A cell adhesion to ECM triggered MAPK/ERK signaling resulting in upregulation of BRCA2 mRNA and protein, with negligible effects upon cell proliferation. Disruption of MAPK/ERK with PD98059 prevented any BRCA2 upregulation inhibiting DNA synthesis below basal levels. PC-3 cells exhibited a defective MAPK/ERK pathway that was unresponsive to adhesion to the ECM, which instead triggered PI 3-kinase/AKT signaling leading to BRCA2 protein depletion and cell proliferation. Reconstitution of MAPK/ERK by recombinant expression of a constitutively active form of MAPK kinase 1 (MEK1) effectively reversed the neoplastic phenotype by increasing BRCA2 expression and preventing any aberrant cell proliferation at rest and upon interaction with ECM proteins. Our results suggest that aberrant loss of MAPK/ERK activity in prostate cancer may play a pivotal role in the malignant phenotype, and provide evidence that interventions aimed at bypassing the signaling block are able to effectively reverse neoplastic unchecked cell proliferation.

Up-regulation of Skp2 after prostate cancer cell adhesion to basement membranes results in BRCA2 degradation and cell proliferation

Aberrant interaction of carcinoma cells with basement membranes (BM) is a fundamental pathophysiological process that initiates a series of events resulting in cancer cell invasion and metastasis. In this report, we describe the results of our investigations pertaining to the events triggered by the adhesion of normal (PNT1A) and highly metastatic (PC-3) prostate cells onto BM proteins. Unlike PNT1A, PC-3 cells adhered avidly to Matrigel BM matrix as well as to isolated collagen type IV, laminin, and heparan sulfate proteoglycan perlecan, main BM components. This aberrantly increased cancer cell adhesion resulted in sustained BRCA2 protein depletion and vigorous cell proliferation, a cascade triggered by beta1 integrin-mediated phosphatidylinositol 3-kinase activation leading to BRCA2 degradation in the proteasome. This latter effect was orchestrated by phosphatidylinositol 3-kinase-dependent up-regulation of Skp2, a subunit of the Skp1-Cul1-F-box protein ubiquitin complex that directly associates with BRCA2 as demonstrated by coimmunoprecipitation assays, determines its ubiquitination, and ultimately targets it for proteasomal degradation. Inhibition of Skp2 expression by small interference RNA prevented BRCA2 depletion and inhibited the trophic effect upon cell proliferation. These results provide additional evidence on the role of BRCA2 as a modulator of cancer cell growth and elucidate the molecular mechanisms involved in its down-regulation in cancer cells when interacting with BM, a crucial step in the biology of metastasis. Furthering the understanding of this molecular pathway may prove valuable in designing new therapeutic strategies aimed at modifying the natural history of prostate carcinoma.

Is there an association between ocular adnexal lymphoma and infection with Chlamydia psittaci?

Various subsets of extranodal marginal zone lymphomas of mucosa-associated lymphoid tissues (MALT lymphomas) have been associated with infectious organisms. Most notable of these is the association of gastric MALT lymphomas with Helicobacter pylori infection. In a recent publication Ferreri et al. [Ferreri AJ, Guidoboni M, Ponzoni M, De Conciliis C, Dell'Oro S, Fleischhauer K, et al. Evidence for an association between Chlamydia psittaci and ocular adnexal lymphomas. J Natl Cancer Inst 2004;96:586-94] reported the presence of C. psittaci DNA in 80% of 40 ocular adnexal lymphomas. Similar to the gastric MALT lymphoma data, a subset of these patients responded well to antibiotic treatment. We analyzed a set of ocular adnexal lymphomas and benign (non-neoplastic) lesions for evidence of C. psittaci DNA in patients from New York State. No evidence of C. psittaci DNA was seen in seven MALT-type ocular adnexal lymphomas, four non-MALT ocular lymphomas, one Langerhans histiocytosis, and five reactive lymphoproliferations. We eliminated several possible reasons that would cause our study to fail to find C. psittaci DNA, including the presence of PCR inhibitors, inadequate template DNA, and sequence diversity in the target region in C. psittaci. The positive data were based primarily on patients from Italy, while our study involved only patients living in the Northeastern United States. This would suggest possible geographic differences in the etiology of ocular adnexal lymphomas.

Down-regulation of BRCA2 expression by collagen type I promotes prostate cancer cell proliferation

BRCA2 is a tumor suppressor gene that when mutated confers an increased susceptibility to developing breast and prostate carcinoma. Besides its role in mediating DNA repair, new evidence suggests that BRCA2 may also play a role in suppressing cancer cell growth. Because altered interactions between neoplastic cells and the surrounding extracellular matrix (ECM) play a pivotal role in unchecked cancer cell proliferation and metastatic progression, we hypothesized that the ECM may have an effect in BRCA2 expression. By using normal and prostate carcinoma cell lines, we demonstrated that although normal cells transiently increase BRCA2 protein levels when adhering to the ECM protein collagen type I (COL1), carcinoma cells exhibit a significant reduction in BRCA2 protein. This aberrant effect is independent from de novo protein synthesis and results from COL1-beta(1) integrin signaling through phosphatidylinositol (PI) 3-kinase leading to BRCA2 ubiquitination and degradation in the proteasome. BRCA2 protein depletion after cancer cell adhesion to COL1 or in small RNA interference assays triggers new DNA synthesis, a trophic effect that is abrogated by recombinant BRCA2 expression. Blocking or inhibiting beta(1) integrin, PI 3-kinase, or proteasome activity all have a negative effect on COL1-mediated DNA synthesis in cancer cells. In normal cells, the transient increase in BRCA2 expression is independent from beta(1) integrin or PI 3-kinase and has no effect in cell proliferation. In summary, these results unravel a novel mechanism whereby prostate carcinoma cell proliferation is enhanced by the down-regulation of BRCA2 expression when interacting with COL1, a major component of the ECM at osseous metastatic sites.

Optimal dosing and triggers for prophylactic use of platelet transfusions

Despite the reliance on platelet transfusion support in patients receiving myeloablative therapy, controversies surround platelet transfusion practices. These include the appropriate platelet dose and the threshold at which prophylactic platelet transfusions will be most effective. These issues bear directly on patient outcome (donor exposure and bleeding complications), cost effectiveness of transfusion, and maintenance of adequate platelet inventories. This review examines the recent studies that have taken on the task of resolving these questions in order to provide optimal platelet transfusion guidelines. Studies now have convincingly demonstrated that a 10,000/microL threshold for prophylactic platelet transfusion is safe and effective in uncomplicated thrombocytopenic patients. Although platelet dosages vary, in general, smaller doses are both effective and inventory-sparing in the more complicated inpatient setting, while larger platelet doses allow for an increased transfusion interval for chronic outpatient support.

Mechanism underlying factor VII deficiency in Jewish populations with the Ala244Val mutation

We investigated a Sephardic Jewish patient with a mild bleeding diathesis whose plasma levels of factor VII coagulant activity and factor VII antigen were 7% and 9% of normal, respectively. Sequencing demonstrated homozygosity for the Ala244Val mutation and the Arg353Gln polymorphism, which is associated with a modest decrease in factor VII levels. To elucidate the mechanism by which Ala244Val reduced factor VII levels in this patient, transient transfections were performed in COS-1 cells with wild type and mutant factor VII cDNAs and factor VII antigen levels in cell lysates and conditioned media were measured. The secretion of the mutant protein (FVII244V) into the media was 20% of wild type (FVIIwt), and intracellular levels of FVII244V were 60% of FVIIwt. A construct encoding Ala244Val along with the Arg353Gln polymorphism decreased the factor VII level in the media to that observed in the patient's plasma. Pulse-chase experiments demonstrated that FVII244V did not accumulate intracellularly and that low levels of the abnormal protein were maintained throughout the chase. To test the hypothesis that FVII244V results in an unstable molecule, amino acids with smaller (Gly) or larger (Phe) side chains were substituted for Val244 by site-directed mutagenesis. Transient transfection assays with these constructs demonstrated that the side chain of amino acid 244 is crucial in maintaining a proper conformation of the molecule. We conclude that Ala244Val results in a factor VII molecule that is unstable and is probably degraded intracellularly.

Characterization of two naturally occurring mutations in the second epidermal growth factor-like domain of factor VII

We investigated the mechanisms responsible for severe factor VII (FVII) deficiency in homozygous Italian patients with either Gly97Cys or Gln100Arg mutations in the second epidermal growth factor domain of FVII. Transient expression of complementary DNA coding for the mutations in COS-1 cells showed impaired secretion of the mutant molecules. Using stably transfected Chinese hamster ovary (CHO) cells, we performed pulse-chase labeling studies, immunohistochemistry, and experiments with inhibitors of protein degradation, showing that FVII-Cys97 did not accumulate intracellularly but was degraded in a pre-Golgi, nonlysosomal compartment by a cysteine protease. In stably transfected CHO cells expressing FVII-Arg100, the level of intracellular FVII was not increased by several inhibitors of protein degradation, but FVII-Arg100 was retained in the endoplasmic reticulum for a longer period of time than wild-type FVII. FVII-Arg100 had a lower apparent molecular weight than did wild-type FVII under nondenaturing conditions, which is attributable to misfolding due to abnormal disulfide bond formation.

The Arg353Gln polymorphism reduces the level of coagulation factor VII. In vivo and in vitro studies

Factor VII levels are regulated by environmental and genetic factors. Two polymorphisms, a G-to-A transversion at nucleotide 10,976 resulting in Arg353Gln and a decanucleotide insert at position -323 in the 5'-flanking region of the factor VII gene, have been associated with a 20% to 25% reduction in plasma factor VII levels. However Arg353Gln almost always segregates on alleles containing the insert in UK and Italian populations, thereby making it impossible to independently evaluate the impact of Arg353Gln on factor VII levels in these ethnic groups. We have evaluated the influence of genotype on factor VII levels in 99 healthy Polish blood donors and observed that Arg353Gln frequently occurs in the absence of the insert. In univariate analysis, the mean levels of factor VII coagulant activity (VII:C) and factor VII antigen (VII:Ag) were significantly lower in 16 people who were heterozygous for Arg353Gln and the insert compared with 72 normal subjects who had neither Arg353Gln nor the insert (88.8% of normal and 83.1% versus 102% and 100%, P = .019 and P = .0003, respectively). In nine subjects heterozygous for Arg353Gln alone, VII:C and VII:Ag were significantly decreased compared with the normal subjects (81.9% and 83%, respectively, P = .007 and P = .004). In multivariate analysis, Arg353Gln but not the insert significantly reduced VII:C and VII:Ag after adjustment for age and plasma triglycerides (P < .05 and P = .02, respectively). To evaluate the mechanism responsible for reduced factor VII levels in individuals with Arg353Gln, we performed transient transfection assays with factor VII cDNA containing the base substitution resulting in Gln353 and wild-type factor VII cDNA in COS-1 cells. The levels of VII:Ag in the cell lysates were similar, but the amino acid substitution significantly reduced factor VII secretion into the media to 74.9% of wild-type (P = .0001). Based on these in vivo and in vitro studies, we conclude that the Arg353Gln polymorphism alone can decrease plasma factor VII levels.

Severe factor VII deficiency due to a mutation disrupting a hepatocyte nuclear factor 4 binding site in the factor VII promoter

Although small deletions, splice site abnormalities, missense, and nonsense mutations have been identified in patients with factor VII deficiency, there have been no reports of mutations in the factor VII promoter. We investigated a girl with factor VII levels that were less than 1% of normal in association with a severe bleeding diathesis. The patient is homozygous for a T to G transversion that occurs 61 bp before the translation start site. This nucleotide is in a sequence that is an hepatocyte nuclear factor 4 (HNF-4) binding site within the factor VII promoter (ACTTTG AE-->ACGTTG). Using gel mobility shift assays, we show that the mutation disrupts the binding of HNF-4 to its cognate binding site. In growth hormone reporter gene assays, the activity of a plasmid containing the mutant promoter was 6.7% of the wild-type promoter plasmid. Although HNF-4 was able to transactivate the wild-type factor VII promoter 5.4-fold in HeLa cells, no transactivation could be shown with the mutant promoter. These findings indicate that HNF-4 exerts a major positive regulatory effect on factor VII expression and provides in vivo evidence that binding of this transcription factor is critical for normal factor VII expression.

A Thr359Met mutation in factor VII of a patient with a hereditary deficiency causes defective secretion of the molecule

We elucidated the genetic basis responsible for factor VII deficiency in an Italian woman with a severe bleeding diathesis. In the allele inherited from the patient's father, we identified a G to A mutation at nucleotide 6070 at the 5' splice site of intron 4 and a G to A substitution at nucleotide 10976 resulting in the Arg353Gln polymorphism. The maternal allele demonstrated a C to T substitution at nucleotide 10994 resulting in Thr359Met. The mutation at nucleotide 6070 alters an invariant GT dinucleotide and disrupts normal mRNA processing. To investigate the mechanism by which Thr359Met reduces factor VIl levels, we expressed wild type factor VII cDNA (FVIIwt) and a mutant factor VII cDNA containing the base substitution resulting in Met359 (FVII359M) in Chinese hamster ovary cells (CHO). In cells transfected with the mutant factor VII cDNA, FVII359M accumulated intracellularly, and no factor VII was detected in the media after 3 hours of chase. The carbohydrate side chains associated with FVII359M were sensitive to Endo H digestion, which indicates that the protein is retained in the endoplasmic reticulum. Analysis of cell lysates also showed that FVII359M was associated with the 78 kD protein corresponding to GRP78/BiP. We conclude that a Thr359Met mutation in factor VII results in a severe secretion defect that probably results from abnormal folding of the molecule.

Low prevalence of the factor V Leiden mutation among "severe" hemophiliacs with a "milder" bleeding diathesis

Patients with hemophilia A and B and factor levels than 1 percent of normal bleed frequently with an average number of spontaneous bleeding episodes of 20-30 or more. However there are patients with equally low levels of factor VIII or factor IX who bleed once or twice per year or not at all. To examine whether the presence of a hereditary defect predisposing to hypercoagulability might play a role in ameliorating the hemorrhagic tendency in these so-called "mild severe" hemophiliacs, we determined the prevalence of prothrombotic defects in 17 patients with hemophilia A and four patients with hemophilia B selected from 295 and 76 individuals with these disorders, respectively, followed at a large Italian hemophilia center. We tested for the presence of the Factor V Leiden mutation by PCR-amplifying a fragment of the factor V gene which contains the mutation site and then digesting the product with the restriction enzyme MnlI. None of the patients with hemophilia A and only one patient with hemophilia B was heterozygous for Factor V Leiden. None of the 21 patients had hereditary deficiencies of antithrombin III, protein C, or protein S. Our results indicate that the milder bleeding diathesis that is occasionally seen among Italian hemophiliacs with factor levels that are less than 1 percent cannot be explained by the concomitant expression of a known prothrombotic defect.

Determinants of plasma factor VIIa levels in humans

Several enzymes can activate factor VII in vitro, but the protease responsible for generating factor VIIa in vivo has not been determined. Using recombinant tissue factor that has undergone a COOH-terminal truncation, a sensitive functional assay has been established for measuring plasma factor VIIa levels. To evaluate the mechanism responsible for the generation of factor VIIa in vivo, we measured the levels of this enzyme after administering purified concentrates of factor IX and factor VIII to patients with severe deficiencies of these clotting factors. In patients with hemophilia B, factor VIIa levels were initially reduced to 0.5 +/- 0.1 ng/mL and gradually increased to normal after infusing 100 U/kg of body weight (BW) of factor IX. Despite these increases, there were no significant changes in the generation of factor Xa or thrombin. In patients with hemophilia A, only a slight reduction in factor VIIa levels (2.5 +/- 1.3 ng/mL) was observed as compared with controls (3.3 +/- 1.1 ng/mL) and no significant changes were observed after factor VIII levels were normalized. The administration of recombinant factor VIIa (10 micrograms/kg BW) to patients with factor VII deficiency increased the mean circulating level of the enzyme to 118 ng/mL, but this only resulted in normalization of the levels of the activation peptides of factor IX and factor X. The above data indicate that factor IXa is primarily responsible for the basal levels of free factor VIIa generated in vivo (ie, in the absence of thrombosis or provocative stimuli) and that changes in the plasma concentrations of free factor VIIa in the blood do not necessarily lead to alterations in the extent of factor X activation.

Molecular analysis of Polish patients with factor VII deficiency

We analyzed the mutations in patients from 10 Polish kindreds with a bleeding diathesis due to factor VII deficiency. Patients from eight families had plasma levels of factor VII coagulant activity (VII:C) and factor VII antigen (VII:Ag) that were less than 4% of normal. The coding sequence of the factor VII gene was amplified from genomic DNA by polymerase chain reaction (PCR). Sequencing demonstrated a C to T transition at position 10798 resulting in Ala294Val, a G to A transition at 10976 resulting in Arg353Gln, and a single bp deletion at 11125 to 11128 causing a frameshift mutation in the triplet encoding amino acid 404. Homozygosity for the three sequence alterations was confirmed with the restriction enzymes AvaII and MspI and allele specific PCR, respectively. A homozygous patient from a ninth family with levels of VII:C and VII:Ag of 4% and 17%, respectively, had Ala294Val and the frameshift mutation, but not Arg353Gln. Investigation of a homozygous patient from a tenth kindred with VII:C and VII:Ag of 11% and 47%, respectively, demonstrated Ala294Val and Arg353Gln, but not the frameshift mutation. Based on the above data, we conclude that the frameshift mutation in the codon for amino acid 404 is associated with marked reductions in VII:C, Arg353Gln can decrease plasma levels of factor VII in the presence of other mutations in the factor VII gene, and Ala294Val results in a dysfunctional factor VII molecule.

Are capillary whole blood coagulation monitors suitable for the control of oral anticoagulant treatment by the international normalized ratio?

The 512 Coagulation Monitor is a portable coagulation photometer that uses disposable cartridges containing a lyophilized rabbit brain thromboplastin to measure the PT for capillary whole blood. It has been proposed as a suitable system for patient self monitoring at home, but its performance has never been thoroughly assessed for results expressed as International Normalized Ratio (INR). In particular, there is no available information about the adequacy of the WHO calibration model with the Monitor. The aims of the study were to determine the International Sensitivity Index (ISI) against the secondary International Reference Preparation for rabbit thromboplastin and to assess the precision of the INR. The study demonstrates that the Monitor can be calibrated with the WHO model, because log-transformed PTs for patients stabilized on oral anticoagulants and normal individuals are linearly related and because the same orthogonal regression line describes patient and normal data points adequately. However, the ISI calculated in this study (2.715) is higher than that adopted by the manufacturer (2.036). The between-assay reproducibility of the Monitor is acceptable (CV = 9.7%) with results expressed in seconds, but become unacceptably poor when the results are converted into INR (CV = 18.8%) because of the high ISI value of the thromboplastin used. We think that the Monitor might be suitable for monitoring oral anticoagulant therapy if the manufacturer would provide a more sensitive thromboplastin in the cartridges.

Effects of hirudin on activated partial thromboplastin time determined with ten different reagents

Hirudin prolongs the APTT when added to normal plasma and the extent of prolongation depends on the type of reagent used. The aim of this study was to compare the dose-response curves of 10 widely used APTT reagents for linearity and parallelism. On each of 10 working days a normal pooled plasma was mixed with increasing amounts of recombinant hirudin (HBW023) ranging from 0 to 5 micrograms/ml and tested for APTT by photo optical coagulometer. Within each working day, clotting times were measured in duplicate and the order of testing with each reagent was changed every day. Results were expressed as ratios of clotting times with hirudin to clotting times without hirudin, and the values plotted against the hirudin concentration on a log-log scale. The dose-response curves for all reagents were linear over 0.3-1.2 micrograms/ml. The reagent-related slopes ranged from 0.225 +/- 0.003 to 0.303 +/- 0.003 (mean +/- SE) and were significantly different. Precision studies indicated that the least sensitive reagent was also the least precise. These findings indicate that the clotting time values obtained for patients treated with hirudin will vary depending on the APTT reagent used.

Markers of procoagulant imbalance in patients with localized melanomas and autoimmune disorders

Hypercoagulability can be defined as a condition of procoagulant imbalance due to heightened enzymatic activation of coagulation zymogens, but with no laboratory evidence of fibrin deposition nor clinical signs of thrombosis. The imbalance can be detected by measuring the plasma levels of prothrombin fragment 1 + 2 (F1 + 2), fibrinopeptide A (FPA) and thrombin-antithrombin III (TAT) complexes. The aims of this study were to establish the frequency of existence and biochemical pattern of hypercoagulability in patients with cancer and autoimmune disorders, clinical conditions associated with an increased risk of thrombosis, and to ascertain the most sensitive method for its diagnosis. In approximately one-fourth of the patients hypercoagulability was identified by finding high levels of FPA F1 + 2 or TAT unaccompanied by signs of fibrin deposition (expressed by normal levels of D-dimer). In a smaller proportion of patients (approximately 10%), the concomitant presence of high levels of D-dimer indicated that the activation of the coagulation cascade had gone beyond the stage of heightened enzymatic activity to the point of cross-linked fibrin deposition. Of the markers used to detect hypercoagulability. FPA seems to be the most sensitive, being significantly increased in all clinical conditions studied.