Reelin levels are increased in synovial fluid of patients with rheumatoid arthritis.

OBJECTIVES: To evaluate the presence and the glycosylation pattern of reelin in synovial fluid and serum of patients affected by different rheumatic pathologies. METHODS: Reelin levels were evaluated in patients affected by rheumatoid arthritis (RA), psoriatic arthritis (PsA), spondyloarthritis (SpA) and osteoarthritis (OA). Reelin semi-quantitative assays were performed by western blot. The glycosylation pattern was evaluated by immunoblotting performed by sepharose conjugated lectins. RT-PCR was used to detect the presence of mRNA encoding for reelin and its receptors. RESULTS: Reelin is detectable in both sinovial fluids and sera and its levels are more elevated in patients affected by RA with respect to those affected by other inflammatory and non inflammatory joint diseases. The glycosylation pattern of the protein differs in synovial fluid and serum. Fibroblast-like synoviocytes (FLS) express the mRNAs encoding for reelin and its receptors. CONCLUSIONS: Since its levels are higher in RA then in the other analysed pathologies, reelin can represent a candidate suitable for the differential diagnosis of this pathology. Moreover, the observation that this protein is encoded by FLS and differentially glycosylated in blood and synovial fluid supports the hypothesis that it is locally produced in the joints, where it could play an important role in RA development and maintenance.

Toll-like receptor 4 (TLR4) gene polymorphisms in giant cell arteritis.

OBJECTIVE: To investigate potential associations between toll-like receptor 4 (TLR4) gene polymorphisms and susceptibility to, and clinical features of giant cell arteritis (GCA). METHODS: A total of 155 patients with biopsy-proven GCA who were residents of Reggio Emilia, Italy, and 210 population-based controls from the same geographical area were genotyped for two coding single nucleotide polymorphisms of TLR4 (Asp299Gly and Thr399Ile) by molecular methods. The patients were subgrouped according to the presence or absence of polymyalgia rheumatica and severe ischemic complications (visual loss and/or cerebrovascular accidents). RESULTS: The distribution of allele and genotype frequencies did not differ significantly between GCA patients and healthy controls. Carriers of the -299 G allele (G/A+ G/G) [odds ratio (OR) 1.78, 95% confidence intervals (CI) 0.90-3.50)] were more frequent among GCA patients than among the controls, but the difference was not statistically significant. No significant associations were found when GCA patients with and without PMR or with and without severe ischemic complications were compared. CONCLUSION: Our data suggest that the TLR4 gene polymorphisms are not associated with susceptibility to, and clinical expression of, GCA in Italian patients.

-463 G/A myeloperoxidase promoter polymorphism in giant cell arteritis.

OBJECTIVE: To investigate potential associations between-463 G/A myeloperoxidase (MPO) promoter polymorphism and susceptibility to, and clinical features of giant cell arteritis (GCA). METHODS: A total of 156 patients with biopsy-proven GCA who were residents of Reggio Emilia, Italy, and 235 population-based controls from the same geographic area were genotyped for-463 G/A promoter polymorphism of the MPO gene by molecular methods. The patients were subgrouped according to the presence or absence of polymyalgia rheumatica and severe ischaemic complications (visual loss and/or cerebrovascular accidents). RESULTS: The distribution of the MPO-G/A genotype differed significantly between patients with GCA and the controls (p(corr) = 0.003). Allele G was significantly more frequent in patients with GCA than in the controls (p(corr) = 0.0002, OR 2.0, 95% CI 1.4 to 2.9). Homozygosity for the G allele was significantly more frequent in patients with GCA than in controls (p(corr) = 0.0002, OR 2.2, 95% CI 1.4 to 3.4). No significant associations were found when patients with GCA with and without polymyalgia rheumatica or with and without severe ischaemic complications were compared. CONCLUSIONS: Our findings show that the-463 G/A promoter polymorphism of the MPO gene is associated with GCA susceptibility and support a role for MPO in the pathophysiology of GCA.

The codon 72 polymorphic variants of p53 in Italian rheumatoid arthritis patients.

OBJECTIVE: The p53 tumor suppressor protein plays an important role in cell apoptosis. The wild type p53 protein presents a common polymorphism at position 72 resulting in either a proline or an arginine residue at this position, leading to differences between the two variants in the induction of apoptosis. We examined the possible associations of this polymorphism with the occurrence of rheumatoid arthritis (RA) and its severity in a series of RA patients of Italian origin. METHODS: 170 consecutive RA patients fulfilling the 1997 ACR criteria and seen over a 4-month period in our rheumatology centre were studied. The medical records of the patients were reviewed for demographic and clinical parameters. Radiographs of the hands and feet taken at disease onset and after 5 years were available for 122 of the patients and were used to determine the presence and number of erosions, which were scored according to the modified Sharp/van der Heijde method (S/vdH). All of the RA patients and controls were genotyped by the polymerase chain reaction and allele-specific oligonucleotide techniques for p53 gene polymorphism Arg/Pro at codon 72. RESULTS: The distribution of the polymorphism of Arg/Pro 72 did not differ significantly between patients and healthy controls (Arg/Arg 47.1 vs 48.5%, Arg/Pro 43.5% vs 42%, Pro/Pro 9.8 vs 9.5% respectively, p=ns). Patients carrying the Pro/Pro genotype had a significantly higher percentage of erosive disease at year 5 compared with patients carrying the Arg/Arg genotype (Pro/Pro 93%, Arg/Arg 52%, p=0.0001). The mean number of eroded joints per patient at 5 years was higher in the Pro/Pro subgroup and significantly lower in the Arg/Arg subgroup (Pro/Pro 13.2, Arg/Arg 3.6, p=0.0001). The mean S/vdH erosive score, joint space narrowing score and total damage score were significantly higher in the Pro/Pro subgroup compared with the Arg/Arg and Arg/Pro subgroups. CONCLUSION: In the Italian population there is no association between codon 72-p53 gene polymorphism and the occurrence of RA. However, this polymorphism is associated with the structural damage of the disease.

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy.

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is an inherited autosomal dominant condition characterized by migrane, recurrent stroke, subcortical dementia, and pseudobulbar palsy. It begins with migraine with aura in -33% of patients. CADASIL is commonly overlooked or misdiagnosed owing to its recent identification. The pathological hallmark of angiopathy is the presence of multiple, small, deep cerebral infarcts, leucoencephalopathy, and nonatherorosclerotic, nonamyloid angiopathy involving mainly small, deep perforating cerebral arteries. Changes also are present in vascular smooth muscle cells and consist in the presence of granular osmiophilic material (GOM). The defective gene in CADASIL is Notch 3, which encodes a large transmembrane receptor. Magnetic resonance imaging shows high intensity signal lesions, often confluent, and areas of cystic degeneration of subcortical white matter and basal ganglia. Diagnostic strategies in CADASIL are matter of discussions because the electron microscopic demonstration of GOM was reported in 100% of symptomatic patients of French authors, but only in 45% of a British study. GOMs are not present in presymptomatic patients.

An Italian case of CADASIL with mutation CGC-TCG in codon 1006, exon 19 Notch3 gene.

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is commonly overlooked or misdiagnosed owing to its recent identification. It is characterized clinically by recurrent cerebral infarcts, usually appearing between the ages of 30 and 50 years, subcortical dementia, and pseudobulbar palsy. It begins with migraine with aura in approximately one-third of patients. The pathological hallmark of angiopathy is the presence of characteristic granular osmiophilic material (GOM) within the basal lamina of smooth muscle cells. The defective gene in CADASIL is Notch3, which encodes a large transmembrane receptor, and 70% of missense mutations are in exons 3 and 4. Each gene defect leads to either a gain or loss of a cysteine residue in the extracellular N-terminal domain of the molecule. We report the case of a 53-year-old woman admitted to the hospital for transient ischemic attack and stroke-like episodes recurrent since age 43 years. The patient had pseudobulbar palsy, pyramidal signs, and cognitive impairment but not frank dementia. Cerebral MRI showed periventricular diffuse and confluent ischemic lesions. Ultrastructural study revealed an abnormal deposition of granular osmiophilic material (GOM) within the basal lamina in skin capillaries. Direct sequence analysis of the Notch3 gene was performed. Since no mutation was detected in exons 3 and 4, the remaining exons were sequenced and a missense mutation, CGC-TGC in codon 1006 of exon 19 was found. The mutation led to a gain of a cysteine residue. This is the first missense mutation in codon 1006 of exon 19 of the Notch3 gene to be described in Italy and the second reported in the literature.

Intercellular adhesion molecule 1 gene polymorphisms in polymyalgia rheumatica/giant cell arteritis: association with disease risk and severity.

OBJECTIVE: Intercellular adhesion molecule 1 (ICAM-1) is widely distributed in shoulder synovial membrane of active polymyalgia rheumatica (PMR) and strongly expressed in granulomatous inflammatory infiltrate of the temporal artery in giant cell arteritis (GCA). ICAM-1 genes may contribute to the inflammatory PMR/GCA processes. We examined potential associations of ICAM-1 gene polymorphisms with PMR/GCA susceptibility and severity. METHODS: We enrolled 121 consecutive patients with "pure" PMR and 56 patients with biopsy positive GCA residing in Reggio Emilia, Italy. Among patients with PMR, 91 had a followup duration of at least one year. Selected as control subjects were 228 healthy blood donors, 75 patients with nonarteritic central retinal artery occlusion, and 116 cataract surgery patients from the same geographic area. All PMR/GCA patients and controls were genotyped by polymerase chain reaction and allele-specific oligonucleotide techniques for ICAM-1 polymorphism at codon 241 (exon 4) and codon 469 (exon 6). RESULTS: The frequency of R241 was significantly higher in PMR/GCA patients [p = 0.00001, odds ratio (OR) 5.0 (95% confidence intervals, CI 2.6-9.6) ], in pure PMR patients [p = 0.00001, OR 5.0 (95% CI 2.5-10.0)], and in GCA patients [p = 0.00005; OR 5.0 (95% CI 2.2-11.5)] compared to the healthy controls. The frequency of R241 was significantly higher in total PMR/GCA patients compared to patients with nonarteritic central retinal artery occlusion [p = 0.0007; OR 5.3 (95% CI 1.8-15.5)] and cataract surgery patients [p = 0.0003; OR 4.1 (95% CI 1.8-9.0)]. The distribution of E/K 469 genotype was similar in PMR/GCA patients and in the 3 control groups. Cox proportional hazards modeling identified 2 variables that independently increased the risk of PMR relapse/recurrence: erythrocyte sedimentation rate at diagnosis > 72 mm/h [relative risk 1.6 (95% CI 1.1-2.3)] and the presence of R241 allele [relative risk 1.6 (95% CI 1.1-2.4)]. CONCLUSION: Our findings show that G/R 241 polymorphism of ICAM-1 is associated with PMR/GCA susceptibility and confers an increased risk of relapse/recurrence in PMR.

Increased plasma levels of platelet-derived growth factor (PDGF-BB + PDGF-AB) in patients with never-treated mild essential hypertension.

Platelet-derived growth factor (PDGF) could play a role in both vascular hypertrophy and atherosclerotic disease associated with hypertension. To assess whether plasma PDGF level is increased in mild essential hypertension, we measured plasma PDGF concentration in 25 never-treated patients with uncomplicated mild essential hypertension and in 22 normotensive healthy subjects. To evaluate the contribution of platelets to plasma PDGF in the two groups, we also measured plasma beta-thromboglobulin (BTG). Measurement of PDGF was carried out through an enzyme-linked immunoadsorbent assay, which detects two PDGF dimers, namely PDGF-BB and PDGF-AB. Both plasma PDGF and BTG were higher in the hypertensive than in the normotensive subjects. The ratio of PDGF to BTG was similar in the two groups. Plasma PDGF was weakly correlated with plasma BTG in the normotensive subjects, whereas this relationship was lost in the hypertensive patients. Our results suggest that the increase in plasma PDGF (PDGF-AB + PDGF-BB) in never-treated essential hypertension is mainly due to platelet activation. The increased circulating level of PDGF could play a role in the vascular structural changes associated with hypertension.

Low molecular weight IgM in primary Sjögren's syndrome.

Low molecular weight IgM (LMW IgM), the monomeric subunit of pentameric IgM, was measured in the serum of 27 patients with primary Sjögren's syndrome. LMW IgM was also measured in a control group consisting of 24 patients with psoriatic arthritis (PA) and 8 patients with active rheumatoid arthritis (RA). LMW IgM was found in the majority of patients with primary SS (63%) and those patients had a longer disease duration than those without SS (80.7 +/- 43.9 months vs 37 +/- 18.3, p = 0.01). Although the differences were not significant, SS patients with LMW IgM showed higher rates of: seropositive disease (71% vs 50%), anti-Ro (59% vs 30%) and anti-La antibodies (12% vs 0%), extraglandular involvement (76% vs 60%) and raised gammaglobulins levels (47% vs 30%) compared to those without LMW IgM. Our only two patients with active RA and vasculitis had LMW IgM. None of the patients with PA showed LMW IgM, regardless of their Kammer subgroup classification, disease activity or radiological evidence of erosions. The presence of LMW IgM in a high percentage of patients with primary SS appears to be the expression of a dysregulation of B cell state that may predispose these patients to developing malignant lymphoproliferation.

Recombinant human erythropoietin therapy in patients with rheumatoid arthritis with the anemia of chronic disease.

We treated 5 patients with rheumatoid arthritis (RA) with anemia of chronic disease with recombinant human erythropoietin (rHuEPO) for 11 weeks. An increase in hematocrit (Hct) greater than 5 was seen in 4 patients after 4 weeks of therapy. The 5th patient had a significant rise in Hct when the dosage of rHuEPO was increased to 150 units/kg from the 4th to 7th week. The subcutaneous administration of rHuEPO dose, reduced by one third with respect to initial dose, maintained an effective Hct value in all the 5 patients during the last 4 weeks of therapy. There was no change in disease activity. In one patient Hct normalization completely resolved symptoms of angina pectoris and permitted hip replacement surgery in another. No side effects occurred during rHuEPO therapy. We conclude that HuEPO is an effective, safe and well tolerated therapy for RA patients with severe anemia of chronic disease.

Evidence of a warfarin-sensitive cancer procoagulant in V2 carcinoma.

Rabbit V2 carcinoma tissue is the tumor in which cancer procoagulant activity (CP) was first described, purified and identified as a cysteine proteinase able to activate F X directly. In the present study we show that CP of V2 carcinoma extracts is depressed in its biological activity (although the antigen is present) by warfarin treatment. The biochemical basis for this effect is offered by the identification of Vit.K-dependent gamma-carboxylase in the microsomal fraction of the tumor tissue. V2 carcinoma tissue had very low endogenous substrate(s) of tumor carboxylase in basal conditions but this increased threefold after warfarin. The accumulation of endogenous substrate(s) and the depression of the CP activity by warfarin raises the possibility that CP represents at least one of the substrates for gamma-glutamyl carboxylase in this experimental tumor tissue.

Procoagulant activity of mouse transformed cells: different expression in freshly isolated or cultured cells.

This study was originally designed to investigate whether there is any correlation between the type of procoagulant activity (PCA) and the tumorigenicity of transformed cells. The data obtained are relevant to this question and to defining the differences in the expression of cellular activities depending on the in vitro system used. PCA was measured and characterized in normal, immortalized, and tumorigenic mouse fibroblasts. In all the cell lines studied the activity was of tissue factor type, as established with functional, enzymatic, and immunochemical criteria. However, the PCA of cells freshly isolated from the tumors induced by tumorigenic cell lines was of cancer procoagulant type, i.e. a cysteine protease with direct factor X activator activity. The same cells, when cultured in vitro, expressed again PCA of tissue-factor type. These results suggest that either a tumor-host interaction is required for the expression of cancer procoagulant or the latter activity, produced by tumor cells under in vitro conditions, is destroyed or inactivated during the culture period. Our findings caution against defining the procoagulant activity of tumors based on experiments on cultured cells.

DMSO-induced changes in the procoagulant and fibrinolytic activity of B16 melanoma cells: influence on lung colony formation.

In this study DMSO (dimethylsulphoxide) was used as a tool to test the significance of in vitro modifications of procoagulant and fibrinolytic activity of tumor cells for their in vivo metastatic ability. B16 melanoma cells were chosen as the experimental model. After four days' treatment DMSO increased both the procoagulant and fibrinolytic (plasminogen activator) activity of B16 melanoma cells in a dose-related manner. DMSO treated cells showed significantly greater lung colonizing ability than untreated cells. Our results indicate that DMSO treatment in vitro can modulate procoagulant and fibrinolytic activity and the metastatic ability of B16 melanoma cells; however a direct causal relationship between these in vitro and in vivo effects remains to be established.

Mouse tumor-associated macrophages do not generate procoagulant activity in response to different stimuli.

Mononuclear phagocytes, an integral part of the lymphoreticular infiltrate of human and experimental tumors, might contribute to fibrin deposition within malignant tissues through the production of procoagulant activity (PCA). We have studied the PCA of tumor-associated macrophages (TAM) in 2 poorly immunogenic, metastatic murine sarcomas (mFS6 and MN/MCA1); peritoneal macrophages (PM) from tumor-bearing and control animals were also studied, as reference cell populations. PCA was evaluated by a one-stage clotting assay immediately after isolation (basal PCA) and following in vitro stimulation. Basal PCA was very low (less than 1 U/10(4) macrophages) in all cell preparations. Exposure of PM from both normal and tumor-bearing animals to bacterial endotoxin (lipopolysaccharide, LPS), phorbol myristate acetate (PMA) or the chemotactic peptide formyl-methionyl-leucyl-phenylalanine (FMLP) resulted in 10-, 7- and 3-fold increases in PCA, respectively. In contrast, TAM from mFS6 and MN/MCA1 consistently failed to generate PCA in response to different concentrations of the same stimuli. Treatment of TAM with aspirin did not affect cell unresponsiveness. Fluorescence microscopy showed that almost all PM were stained with fluorescein isothiocyanate (FITC)-LPS, while less than 10% of the TAM were stained. These data, coupled with previous evidence that TAM have a lower number of specific binding sites for phorbol esters than PM, suggest that the defective responsiveness of TAM to endotoxin, PMA and, possibly, FMLP, is due to the lack, or very low expression, of binding sites for these agents on the cell surface. The tumor environment may orient the functional status of in situ macrophages in a direction less favorable to the host.

Effects of dimethyl sulfoxide (DMSO) on microfilament organization, cellular adhesion, and growth of cultured mouse B16 melanoma cells.

Cell shape is involved in a variety of cellular activities including proliferation, adhesion, migration, and transformation. Agents known to promote differentiation, such as retinoic acid, butyrate, and dibutyryl cyclic AMP, induce marked alterations in cell shape which are often accompanied by changes in cell functions. In this paper we study the effects of the differentiating polar solvent dimethyl sulfoxide (DMSO) on cytoskeleton, adhesion, and growth properties of cultured mouse B16 melanoma cells. DMSO induced a progressive reorganization of the cytoskeleton which was fully developed in 4 days of continuous exposure to the agent. DMSO-treated cells developed thick and regularly oriented microfilament bundles of the stress fiber type ending at vinculin-rich areas of focal contact between the ventral membrane and the substratum (interference reflection microscopy-dark adhesion plaques). Such a rearrangement of the cytoskeleton resulted in increased adhesion to the substratum and inhibition of cell growth in comparison to control untreated cells. Cells which became highly flattened and tightly adherent after exposure to DMSO for 4 days progressively reverted their phenotype to that of control untreated cells within 3 days of DMSO withdrawal. Namely, they lost stress fibers and adhesion plaques, became rounded and less adherent, and increased their growth rate. These results indicate that DMSO can change the transformed appearance of B16 mouse melanoma cells to a phenotype which is typical of a variety of nontransformed cells in culture.

Several murine metastasizing tumors possess a cysteine proteinase with cancer procoagulant characteristics.

Cancer Procoagulant (CP), a cysteine proteinase which triggers blood coagulation by directly activating Factor X (FX) in the absence of Factor VII (F VII), has recently been isolated from rabbit V2 carcinoma and biochemically characterized. We have studied the procoagulant activity of tissue extracts from 4 murine experimental tumors in order to define whether or not a F VII-independent activity with cysteine proteinase characteristics was present. The tumors studied were: Lewis lung carcinoma (3LL), B16 melanoma (B16), JW sarcoma (JWS) and the M4 variant of the mFS6 fibrosarcoma (M4). Extracts from 3LL, B16 and JWS tumor initiated coagulation in both the presence and absence of F VII, their procoagulant activity was sensitive to iodoacetamide (1 mM) and mercury chloride (0.1 mM). The procoagulant of M4 extract was dependent on the presence of F VII and was not significantly affected by the cysteine proteinase inhibitors. An Ouchterlony double immunodiffusion study showed immunological cross-reactivity of all but M4 extracts to a polyclonal antibody to purified CP. The present study suggests that the procoagulant(s) present in the murine tumors 3LL, B16 and JWS are enzymatically and immunologically indistinguishable from cancer procoagulant of the rabbit V2 carcinoma.

Cancer procoagulant in human tumor cells: evidence from melanoma patients.

It has repeatedly been proposed that fibrin plays a role in tumor growth and metastasis. Among tumor cell products or activities which may promote clot formation, cancer procoagulant (CP), a direct activator of coagulation factor X, has been suggested to be selectively associated with the malignant phenotype. We report here the enzymatic and immunological identification of this cysteine proteinase procoagulant in extracts and cells from human melanoma. CP activity was independent of both the intrinsic and extrinsic pathways of blood coagulation, using factor IX and factor VII deficient plasmas, and was inhibited by the cysteine proteinase inhibitors iodoacetamide and HgCl2. CP activity was detectable in extracts and cell suspensions from all 32 patients studied and was higher in extracts from metastases (14.8 +/- 3.9 units/mg protein) than from the primary tumors (3.7 +/- 1.0 units/mg protein). CP activity was not affected by an anti-apoprotein III antibody or by concanavalin A, a known inhibitor of thromboplastin. In contrast, no CP activity or antigen was detected in extracts from six benign melanocytic lesions. The procoagulant activity was dependent on factor VII and was inhibited by anti-apoprotein III antibody and by concanavalin A, properties that suggest that the procoagulant was tissue thromboplastin. These data indicate that CP can be expressed by human tumor cells and that, among melanotic lesions, its presence is associated with the malignant phenotype and its activity is particularly high in metastatic cells.

Induction of monocyte-macrophage procoagulant activity by transformed cell lines.

Human peripheral blood monocytes and mature macrophages were found to produce significant procoagulant activity (PCA), identified as tissue factor, on exposure to a variety of human (K562, HL60, Raji) and murine (TU5, NS-1) transformed cell lines. The monocyte procoagulant response was vigorous, generating PCA to a level nearly comparable to the response to endotoxin, a known stimulant for monocyte PCA. The response was rapid and could be fully elicited, in a dose-dependent fashion, within 4 hr with HL60 and Raji cell lines and within 14 hr with K562, TU5, and NS-1 cells. The monocyte PCA-inducing activity was found to reside in the membrane fraction of transformed cells. Other transformed human (Laz 509, Laz 221, Laz 156, U937, CEM) and murine (L1210, P815, TLX9, WEHI 164) cell lines had little, if any, activity. The induction of monocyte PCA by transformed cells most probably was not due to an allogeneic signal, as 1) the K562 and HL60 cell lines were potent PCA inducers despite the lack of class II histocompatibility antigen expression, whereas Laz 156, which did express HLA antigens, was ineffective; 2) mouse peritoneal macrophages responded with the production of strong PCA to the syngeneic transformed cell lines TU5 and NS-1. The monocyte-macrophage procoagulant response to transformed cell lines appeared to be independent of T lymphocytes. Indeed, monocytes purified on the basis of reactivity with monoclonal antibody Mo2 and sorting or depleted of contaminating T cells by anti-T3 antibody and complement responded similarly to conventional monocyte preparations. The production of tissue factor by monocyte-macrophages in response to exposure to some tumor cells may represent a mechanism whereby blood coagulation is activated in malignancy.

Vitamin K-dependent procoagulant in cancer cells: a potential target for the antimetastatic effect of warfarin?

Anticoagulants of the coumarin type have long been reported to inhibit metastasis growth in experimental animals; however, the mechanisms of such effects has not been clarified. Systemic anticoagulation per se does not appear to account completely for such metastasis growth depression. More recent information gathered on a cell procoagulant activity, which is vitamin K-dependent, could probably supply a fresh insight into this problem. Indeed, vitamin K deficiency induced either dietarily or pharmacologically by warfarin, does inhibit the activity of a cysteine protease with direct factor-X-activating properties. This protease is only present in warfarin-sensitive tumors. The correlation of this activity with cancer cell invasiveness is supported by experimental data in metastatic variants and, lately, also by the observation of markedly higher cancer procoagulant activity in extracts from metastases than from primary human melanomas.

gamma-Glutamyl carboxylase activity in experimental tumor tissues: a biochemical basis for vitamin K dependence of cancer procoagulant.

Rabbit V2 carcinoma tissues have been described to possess a procoagulant activity with specific characteristics; this material has been purified and identified as a cysteine proteinase able to directly activate coagulation factor X. We have shown here that the procoagulant activity of V2 carcinoma extracts is depressed in warfarin-treated animals, thus suggesting that cancer procoagulant could represent a new vitamin K-dependent protein. The biochemical basis for this effect is offered by the identification of gamma-glutamyl carboxylase in the microsomal fraction of tumor tissues. The V2 carcinoma has a carboxylase activity which is increased in warfarin-treated animals. An endogenous substrate of tumor carboxylase, the nature of which has not been identified, has been found 5-fold increased in warfarin-treated animals. The presence of gamma-glutamyl carboxylase was also described in several murine tumors including both carcinomas and fibrosarcomas. It is worth mentioning that all the tumors tested produce a procoagulant with the peculiar characteristics of that described in V2 carcinoma. It is conceivable that cancer procoagulant could represent at least one of the substrates for gamma-glutamyl carboxylase in these experimental tumor tissues.