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J L Francis

Publications and source records attributed to J L Francis.

At least 19 recordsLinked to original sources
PubMed2006

Enumeration of leukocyte infiltration in solid tumors by confocal laser scanning microscopy.

BACKGROUND: Leukocytes commonly infiltrate solid tumors, and have been implicated in the mechanism of spontaneous regression in some cancers. Conventional techniques for the quantitative estimation of leukocyte infiltrates in tumors rely on light microscopy of immunostained thin tissue sections, in which an arbitrary assessment (based on low, medium or high levels of infiltration) of antigen density is made by the pathologist. These estimates are relatively subjective and often require the opinion of a second pathologist. In addition, since thin tissue sections are cut, no data regarding the three-dimensional distribution of antigen can be obtained. RESULTS: To overcome these problems, we have designed a method to enumerate leukocyte infiltration into tumors, using confocal laser scanning microscopy of fluorescently immunostained leukocytes in thick tissue sections. Using image analysis software, a threshold was applied to eliminate unstained tissue and residual noise. The total antigen volume in the scanned tissue was calculated and divided by the mean cell volume (calculated by "seeding" ten individual cells) to obtain the cell count. Using this method, we compared the calculated leukocyte counts with those obtained manually by ten laboratory personnel. There was no significant difference (P > 0.05) between the cell counts obtained by either method. We then compared leukocyte infiltration into seven tumors and matched non-malignant tissue obtained from the periphery of the resected tissue. There was a significant increase in the infiltration of all leukocyte subsets into the tumors compared to minimal numbers in the non-malignant tissue. CONCLUSION: From these results we conclude that this method may be of considerable use for the enumeration of cells in tissues. Furthermore, since it can be performed by laboratory technical staff, less time input is required by the pathologist in assessing the degree of leukocyte infiltration into tumors.

Antigens, CD↗
PubMed2006

Experimental metastasis and primary tumor growth in mice with hemophilia A.

During experimental lung metastasis, tumor cells adhere to the pulmonary microvasculature and activate coagulation via surface-expressed tissue factor (TF), leading to local fibrin deposition and platelet aggregation. While interventional studies have demonstrated great efficacy of anticoagulants and antiplatelet agents in inhibiting metastasis, no information is available on how tumor biology may be affected by congenital bleeding disorders such as hemophilia A. We therefore used a syngeneic model to study experimental metastasis and primary tumor growth in factor VIII (FVIII)-deficient mice. By conventional reverse transcription-polymerase chain reaction, flow cytometry, and one-stage clotting assays, we demonstrated constitutive expression of TF mRNA, antigen, and procoagulant activity in the murine B16F10 melanoma cell line. In hemophilic mice, B16F10 lung metastasis was significantly (P < 0.001) enhanced by a single dose of human FVIII (100 U kg(-1)), suggesting that FVIII played a critical role during the early blood-borne phase of the metastatic cascade. In contrast, lung seeding was significantly (P < 0.05) reduced by lepirudin, a direct thrombin inhibitor, suggesting that thrombin generation contributed to pulmonary metastasis even in the absence of FVIII. Consistent with this finding, intravenous injection of B16F10 cell-evoked laboratory changes of a hemolytic thrombotic microangiopathy and consumptive coagulopathy in both hemophilic and non-hemophilic mice. Subcutaneous implantation of B16F10 cells into mice with hemophilia A gave rise to primary tumors in an exponential growth pattern similar to that observed in non-hemophilic mice. Although TF expression by B16F10 cells may promote thrombin-dependent metastasis in mice with hemophilia A, amplification of coagulation by host FVIII appears to be necessary for maximum lung seeding.

Animals↗
PubMed2003

Antimetastatic effect of tinzaparin, a low-molecular-weight heparin.

The importance of coagulation activation in cancer patients is suggested by the clinical finding of hypercoagulability, experimental enhancement of metastasis and angiogenesis by coagulation factors such as tissue factor (TF) and thrombin and the possible antitumor effects of anticoagulant agents. Tinzaparin is a low-molecular-weight heparin (LMWH) with a relatively high molecular weight distribution and high sulfate to carboxylate ratio. In addition to its ability to inhibit thrombin and factor Xa, tinzaparin is particularly effective at releasing endothelial tissue factor pathway inhibitor (TFPI), the natural inhibitor of both procoagulant and non-coagulant effects of TF. The present study was undertaken to investigate the effect of tinzaparin on lung metastasis using a B16 melanoma model in experimental mice. Tinzaparin's anticoagulant effect in mice and its ability to release TFPI from human endothelial cells at various time points were demonstrated. Subcutaneous (s.c.) injection of tinzaparin (10 mg kg-1) 4 h before intravenous administration of melanoma cells (2.0 x 105) markedly (89%) reduced lung tumor formation (3 +/- 2) compared with controls (31 +/- 23; P < 0.001). In a second group of animals, tinzaparin (10 mg kg-1, s.c.) administered daily for 14 days following the initial (pretumor cell) dose, before assessment of lung seeding, reduced tumor formation by 96% (P < 0.001). No bleeding problems were observed in any of the tinzaparin-treated animals, despite a 4-fold prolongation of the whole blood clotting time after a single s.c. dose of tinzaparin (10 mg kg-1). Administration of tumor cells (2 x 106) caused a rapid and significant fall in platelet count 15 min after injection (a sensitive marker of intravascular coagulation) in controls (939 +/- 37 vs. 498 +/- 94 x 106 mL-1, P < 0.01), but this was prevented by tinzaparin treatment (921 +/- 104 x 106 mL-1). These data provide further experimental evidence to support the potential for LMWH as antimetastatic agents.

Animals↗
PubMed2002

Hemoglobin binds melanoma cell tissue factor and enhances its procoagulant activity.

Tissue factor (TF), the membrane-bound glycoprotein that normally initiates the coagulation pathway, is expressed on the surface of various cells including endothelial cells, fibroblasts, monocytes and tumor cells. We recently reported that hemoglobin (Hb) enhances TF expression and procoagulant activity on TF-bearing human A375 malignant melanoma cells. To elucidate the mechanism of Hb-induced TF expression, we studied the interaction between purified TF from human A375 malignant melanoma cells and Hb. Selective binding of highly purified melanoma cell TF-apoprotein to Hb was demonstrated under native conditions using a dot-immunobinding assay and under denaturing conditions by Western blotting. The complex formation between purified melanoma cell TF-apoprotein and Hb was also demonstrated by the binding of fluid-phase Hb to immobilized TF-apoprotein (0-2.0 microg/ml) in an enzyme-linked immunosorbent assay. The binding was specific, concentration-dependent, saturable and inhibited significantly (60%) by Concanavalin-A. Hb enhanced the factor X-activating procoagulant activity of melanoma cell TF in a concentration-dependent manner, but had no effect on recombinant human TF. Concanavalin-A and wheat germ agglutinin significantly (60%) inhibited the Hb-induced procoagulant activity of malignant cell TF. We conclude that TF-apoprotein selectively binds Hb, most probably via the carbohydrate moieties (alpha-d-glucosyl; alpha-d-mannosyl and N-acetyl-beta-d-glucosaminyl residues) of TF, and enhances its procoagulant activity. The physiological significance of this interaction remains to be established.

Apoproteins↗
PubMed2002

Platelet-CD40 ligand interaction with melanoma cell and monocyte CD40 enhances cellular procoagulant activity.

Platelet-tumor cell interactions are believed to be important in tumor metastasis. Tumor cell tissue factor (TF) expression enhances metastasis and angiogenesis, and is primarily responsible for tumor-induced thrombin generation and the formation of tumor cell-platelet aggregates. Activated platelets express and release CD40 ligand (CD40L), which induces endothelial TF expression by ligation to CD40. We investigated the effect of platelet-derived CD40L on the TF activity of human CD40-positive melanoma cells and monocytes by incubating supernatants from activated or resting platelets with tumor cells or monocytes, and by bringing resting or activated platelets into close apposition with tumor cell monolayers. CD40L was present on the surface of activated (but not resting) platelets and was also released following platelet activation. Both recombinant soluble CD40L (rsCD40L) and activated platelet supernatants increased procoagulant activity (PCA) and TF antigen in tumor cells and monocytes. The increase in TF activity induced by both rsCD40L and activated platelet supernatants was inhibited by anti-CD40L antibody. Furthermore, contact of activated platelets with tumor cells increased cellular PCA, and this effect was also inhibited by anti-CD40L. In malignancy, the increase in cellular TF activity via CD40 (tumor cell)-CD40L (platelet) interaction may possibly enhance intravascular coagulation and hematogenous metastasis.

Blood Coagulation↗
PubMed2001

Hemoglobin enhances tissue factor expression on human malignant cells.

Tissue Factor (TF) is a transmembrane glycoprotein that complexes with factor VII/activated factor VII to initiate blood coagulation. TF may be expressed on the surface of various cells including monocytes and endothelial cells. Over-expression of TF in human tumor cell lines promotes metastasis. We recently showed that hemoglobin (Hb) forms a specific complex with TF purified from human malignant melanoma cells and enhances its procoagulant activity (PCA). To further study this interaction, we examined the effect of Hb on the expression of TF on human malignant (TF+) cells and KG1 myeloid leukemia (TF-) cells. Human melanoma A375 and J82 bladder carcinoma cells, which express TF at moderate and relatively high levels, respectively, were incubated with varying concentrations (0-1.5 mg/ml) of Hb. After washing, cells were analyzed for Hb binding and TF expression using flow cytometry and confocal microscopy. Hb bound to the cells in a concentration-dependent manner, and increased both TF expression and PCA. The human A375 malignant melanoma cells incubated with Hb (1 mg/ml) expressed up to six times more TF antigen than cells without Hb. This increase in TF expression and PCA of intact cells incubated with Hb was significantly inhibited by cycloheximide at a concentration of 10 microg/ml (P < 0.01). An increase in total cellular TF antigen content was demonstrated by specific immunoassay. In contrast, Hb (5 mg/ml) did not induce TF expression and PCA on KG1 cells as determined by flow cytometry and TF (FXAA) activity. We conclude that Hb specifically binds to TF-bearing malignant cells and increases their PCA. This effect seems to be at least partly due to de novo synthesis of TF and increased surface expression. However, the exact mechanism by which Hb binds and upregulates TF expression remains to be determined.

Carcinoma, Transitional Cell↗
PubMed2001

The relationship between insight and social skill in persons with severe mental illness.

The relationship of insight with the social behaviors of outpatients with severe mental illness (SMI) was investigated. Participants' engaged in two social interactions (i.e., stigmatizing and nonstigmatizing), each with a different research confederate. The participant's behavior was later coded for the presence of various self-presentation and social skill variables. Results indicated that greater insight was associated with better overall social skill, less observed strangeness, and greater self-disclosure of one's mental illness. Furthermore, the three measures of insight, one based on self-report and two interview-based, were all highly intercorrelated, suggesting that they are measuring a similar construct. Finally, consistent with previous research in the area, greater insight was associated with less severe psychiatric symptoms. Implications of these findings for future research are discussed.

Adult↗
PubMed2001

Purification and properties of human melanoma cell tissue factor.

Tissue factor (TF) is a transmembrane glycoprotein that acts as a receptor for nonactivated and activated factor VII (FVII) and triggers the coagulation cascade. TF plays an important role in hemostasis, but may also have noncoagulation functions in vascular development, angiogenesis, and tumor cell metastasis. In tumor cells, analysis of the role of TF has been hampered by the lack of purified TF. In this study, TF antigen was identified on human A375 malignant melanoma cells using flow cytometry. We further purified TF apoprotein 2,000-fold to homogeneity from A375 melanoma cells using immunoaffinity chromatography. On SDS-polyacrylamide gel electrophoresis under reduction, purified TF apoprotein gave two major protein bands corresponding to molecular weights of 53 and 34 to 36 KD. The identity of these forms of TF was confirmed by Western blotting using a polyclonal antibody against human brain TF. Under reduction, the TF antibody bound with a monomeric form of TF (53 KD), and without reduction, to several forms of TF (34 to 128 KD). Preliminary carbohydrate analysis suggested that TF is a glycoprotein and contains about 22% total carbohydrates. The coagulant activity of the purified apoprotein was reconstituted by the addition of phospholipids. The effects of varying concentrations (0 to 8 microg) of polyclonal antibodies to TF and FVII on TF procoagulant activity were studied. Both antibodies inhibited more than 70% of the procoagulant activity of TF in an FX activation assay. The complex formation between purified TF apoprotein and FVIIa was demonstrated by using an enzyme-linked immunosorbent assay. TF formed a complex with FVIIa in a concentration-dependent and saturable manner. We conclude that in human melanoma cells, TF occurs in monomeric and heterodimeric forms and appears to have similar properties as reported for TF from other sources.

Antibodies↗
PubMed2000

Validation of the ISAAC video questionnaire (AVQ3.0) in adolescents from a mixed ethnic background.

BACKGROUND: The International Study of Asthma and Allergies in Childhood (ISAAC) has developed an international version of the asthma video questionnaire (AVQ3.0) to measure asthma prevalence. This questionnaire has not been validated in adolescents from a mixed ethnic background. OBJECTIVE: The aims of this study were to compare the video questionnaire with a written questionnaire in the detection of airway hyperresponsiveness to hypertonic saline in a population of adolescents from a mixed ethnic background, and to establish the repeatability and psychometric properties of the asthma video questionnaire. METHODS: The study was conducted in four secondary schools in Sydney, an area with a high proportion of people from a non-English speaking background. Four hundred and seventy-five students from schools 1 and 2 completed the video questionnaire and a subgroup of these students (n = 170) completed the written questionnaire and a hypertonic saline inhalation challenge. Reproducibility of the questionnaire was evaluated by administering the questionnaire to a subsample of students 2 weeks later. The psychometric properties of the video questionnaire were examined in 852 students at two other schools (schools 3 and 4). RESULTS: One hundred and sixty-nine students aged 13.5 (sd 1.3) years completed both written and video questionnaires, and the hypertonic saline challenge. The students had widely different cultural backgrounds including Asian, South Pacific, Middle Eastern, European and African countries. There was good agreement between the questionnaires for wheeze (kappa 0.42). Questions on the video questionnaire concerning wheezing had good sensitivity (90%) and specificity (68%) for airway hyperresponsiveness to hypertonic saline. The video questionnaire was reproducible (kappa 0.82), had good internal consistency (Cronbach's alpha 0.81) and each question pertained to a single construct explaining 58% of the variance in total score. CONCLUSION: This study has validated the international version of the ISAAC video questionnaire against airway hyperresponsiveness to hypertonic saline in adolescents from a mixed ethnic background, and identified that the questionnaire has good psychometric properties. The ISAAC video has proved to be a valuable tool for the assessment of asthma prevalence in populations of ethnic diversity.

Adolescent↗
PubMed2000

One year in Antarctica: mucosal immunity at three Australian stations.

The effect of a year's isolation in Antarctica on the human mucosal immune system was assessed during the winter of 1992 at three Australian Antarctic stations: Casey, Davis and Mawson. Saliva samples were collected from each expeditioner prior to their departure from Australia and during each month in Antarctica. The concentrations of salivary immunoglobulins IgA and IgG were significantly different between the three stations, but there were no differences for salivary IgM and albumin. The mean concentrations of IgA were higher at Mawson (P < 0.008), and the mean concentrations of IgG were lower at Davis (P < 0.001) compared with the other stations. Ranges of values observed at the stations over the 12-13 months were similar. The variability of values within individuals showed station differences for salivary IgM and IgG only. The study revealed significant changes in salivary immunoglobulin values over the period in Antarctica, with similar patterns at the three Australian stations. The salivary IgA and IgM levels were lower in the first 4 months in Antarctica (January-April) and increased to maximum values in July-August, before returning to mean levels when isolation was broken in October-November. The patterns of salivary IgA and IgM suggest that stressors due to isolation may play a role in alterations of mucosal immunity in expeditioners in Antarctica.

Adult↗
PubMed2000

Urinary tissue factor levels in patients with bladder and prostate cancer.

AIMS: Coagulation activation is a recognized complication of cancer in which increased tissue factor (TF) is implicated. TF can be detected in urine (uTF). This study assesses uTF levels in benign and malignant urological disease and correlates the results with conventional markers of tumour progression. METHODS: Using a simple and reproducible kinetic chromogenic assay, we determined uTF levels in controls (normal volunteers (n = 57) and patients with renal stones (n = 30)), benign and malignant bladder (n = 75) or prostate (n = 106) disease and in patients with or without recurrent bladder cancer (n=30). Each benign disease group was stratified as inflammatory (cystitis or prostatitis) or non-inflammatory (negative cystoscopy following haematuria or benign prostatic hypertrophy). RESULTS: The controls and the benign non-inflammatory results were indistinguishable. The malignant and inflammatory groups showed raised uTF levels over controls (P<0.001 bladder and P<0.01 prostate). The difference between malignant and benign inflammatory disease was only significant for the bladder group. uTF levels were significantly related to histological tumour grading, prostate serum specific antigen, static bone scan images and recurrence status. CONCLUSIONS: uTF levels can distinguish, statistically but not without overlap, patients with malignancy from normal controls and benign non-inflammatory conditions. Discrimination between inflammatory and malignant disease has only been demonstrated in the bladder. uTF levels showed a significant association with markers of tumour progression or metastasis and may be useful in predicting bladder tumour recurrence.

Adult↗
PubMed2000

Immune status and respiratory illness for elite swimmers during a 12-week training cycle.

The impact of a 12-week training program by elite swimmers on systemic and mucosal immunity was studied prospectively to examine the relationship between changes in immune parameters and the incidence of respiratory illness. Saliva was collected before and after selected training sessions at 2 weekly intervals. There were significant decreases in salivary IgA (p=0.05) and salivary IgM (p < 0.0001) concentrations after individual training sessions, but no significant changes in salivary IgG or albumin concentrations. Over the 12-week training program there were small but statistically significant increases in pre-exercise concentrations of salivary IgA (p<0.001), IgM (p=0.015) and IgG (p=0.003) and post-exercise salivary IgA (p <0.001). There were no significant trends over the 12 weeks for any class of serum immunoglobulins but a significant fall in NK-cell numbers (p<0.001). There were no associations between serum or salivary immunoglobulin levels or NK-cell numbers and upper respiratory tract illness (URTI) during the 12-week program. The data indicated that despite changes in some immune parameters during this final training program prior to competition there were no associations detected with URTI for this cohort of elite swimmers.

Adolescent↗
PubMed2000

Platelet dysfunction detected at high shear in patients with heart valve disease.

Whether patients with valvular heart disease have a defect of platelet function has been unclear. Despite evidence that these individuals have an abnormality detectable only under conditions of high shear stress, no methods have been widely available to adequately assess platelet function under such conditions. The Platelet Function Analyzer (PFA)-100 measures platelet function in a high shear environment and is well suited to the detection of platelet dysfunction in the clinical laboratory. The instrument records the time for platelets to occlude a membrane coated with collagen and either epinephrine (CEPI) or ADP (CADP). We studied the PFA-100 in 398 patients before open heart surgery; 308 for coronary artery bypass grafting (CABG) and 90 for aortic or mitral valve replacement (VR). Patients were classified as normal (CEPI < or = 153 s); 'aspirin effect' (CEPI > 153 s but CADP < or = 109 s) or abnormal (CEPI > 153 s and CADP > 109 s). In the CABG group, 41.2% were classified as normal, 43.2% as 'aspirin effect' and 15.6% as abnormal. In contrast, in patients undergoing VR, these values were 6.7, 11.1 and 82.4%, respectively. Patients with valvular disease had significantly longer closure times for both CEPI and CADP tests (P < 0.001). In addition, the valvular disease group had a significantly higher proportion of patients with markedly prolonged (> 150 s) closure times in the CADP cartridge (43.3 vs. 3.6%, respectively). Only one (0.3%) patient in the CABG group had non-closure (> 300 s) in the CADP test compared to seven (7.8%) in the valvular disease group. Three of six patients in the latter group bled excessively during surgery. We conclude that abnormal CADP closure is much more frequent among patients with aortic or mitral valve disease compared to those with coronary artery disease. This may reflect pre-existing high-shear damage to platelets that renders them refractory to subsequent shear activation and aggregation in the PFA-100 system. Further studies are needed to more precisely define the platelet defect in these patients. Markedly prolonged CADP closure in patients with valvular disease may indicate an increased likelihood of intra-operative bleeding, although an appropriately designed prospective study is needed to adequately address this hypothesis.

Adenosine Diphosphate↗
PubMed2000

Monocyte tissue factor levels in cancer patients.

OBJECTIVE: The association between cancer and thromboembolic disease has been known for over a century. Increased tissue factor expression by endothelial cells, monocytes or macrophages is implicated. Thus, monocyte tissue factor measurements may reflect disease presence or progression. METHODS: Using a 2 stage kinetic chromogenic assay, monocyte tissue factor levels were assessed in normal controls (n=60), patient controls (hernia or cholecystectomy, n=60) and in patients with benign and malignant disease of the bladder (n=73), prostate (n=81), breast (n=83) and colorectum (n=62). This was performed as baseline (resting cells) and after 6 hours incubation with (stimulated) and without (unstimulated) lipopolysaccharide. Each benign disease group was sub-divided into inflammatory and non-inflammatory categories. RESULTS: The relative operating characteristic curve for the lipopolysaccharide-stimulated monocyte tissue factor assay showed sensitivity and specificity for cancer, the area under the curve being 0.71. The control groups and the benign non-inflammatory groups gave similar results and were pooled for further analysis. Each malignant group showed higher monocyte tissue factor levels than the control groups for baseline (P< 0.05) and lipopolysaccharide-stimulated cells (P< 0.05). All benign inflammatory groups apart from breast, showed increased monocyte tissue factor levels over controls for baseline (P< 0.05) and lipopolysaccharide-stimulated cells (P< 0.05). In all cases there was no significant difference between the malignant and the benign inflammatory groups. Monocyte tissue factor levels were related to tumor grade or stage, patients' survival time, serum prostate specific antigen and static bone scan images. Levels were also higher in patients with bladder cancer recurrence and in those who subsequently died. CONCLUSION: Lipopolysaccharide-stimulated monocyte tissue factor assay showed sensitivity and specificity for cancer compared to controls. Monocyte tissue factor levels are raised in malignant groups compared to controls and non-inflammatory diseases but not when compared with inflammatory conditions. Stimulated cells give better discrimination between the groups and may be useful in identifying high risk individuals. Monocyte tissue factor levels were related to tumor progression.

Adult↗
PubMed1999

Urinary tissue factor levels in patients with breast and colorectal cancer.

Activation of blood coagulation is a common complication of cancer in man and experimental animals. The causes of such activation may be multifactorial, but increased production of tissue factor (TF) by the host mononuclear cells may be involved. TF is not only produced by human monocytes (mTF) and tumour cells, but is also found in urine (uTF), where measurements might be clinically important. Using a highly reproducible (intra-assay CV 2.3 per cent and inter-assay CV 8.1 per cent) one-stage kinetic chromogenic assay (KCA) developed by this group, uTF levels were measured in controls [healthy volunteers (n = 57), patients with renal stones and a normal ESR (n = 30)] and in patients with benign and malignant diseases of the breast (n = 94) and large bowel (n = 62). Each benign disease group was sub-divided into inflammatory and non-inflammatory categories. There were no significant differences between the controls and the benign non-inflammatory groups, so they were unified for further analysis. Malignant groups, irrespective of tumour types, showed significantly higher uTF levels than controls (p < 0.001 for breast and p < 0.01 for large bowel). Similarly, breast and colorectal benign inflammatory groups showed significant increases over controls (p < 0.01 and p < 0.001, respectively). Patients with malignant disease showed uTF activity above the upper quartile range of the normal control group for breast, 77.3 per cent, and large bowel, 73 per cent. uTF levels were related to histological tumour grading and were higher in non-surviving patients. In conclusion, uTF levels are raised in malignant and inflammatory disease compared with controls and patients with non-inflammatory conditions. uTF levels may reflect tumour progression.

Adolescent↗
PubMed1999

Urinary tissue factor: a potential marker of disease.

Tissue factor (TF) is the main physiological initiator of blood coagulation and may be important in the biology of a variety of solid malignancies, particularly where angiogenesis is a critical factor. TF is frequently encrypted in the plasma membrane of cells in contact with blood, and is exposed only after stimulation by certain agonists. Cancer cells variably express TF and cancer cell lines which exhibit multidrug resistance contain more TF than parental cells. TF is increased in both tumour-associated macrophages and blood monocytes and has been implicated in abnormal coagulation activation seen in patients with inflammatory conditions and cancer. TF is also found in urine (uTF) in a lipid-associated form, probably of kidney origin. uTF levels can be assayed in a cost-effective manner and may be clinically important, particularly in patients with renal disorders and malignancy. uTF levels are not significantly affected by age, gender or cigarette smoking.

Age Factors↗
PubMed1999

Soluble fibrin augments platelet/tumor cell adherence in vitro and in vivo, and enhances experimental metastasis.

There is considerable evidence for a relationship between hemostasis and malignancy. Since platelet adhesion to tumor cells has been implicated in the metastatic process and plasma levels of fibrinogen (Fg) and soluble fibrin (sFn) monomer are increased in cancer, we hypothesized that these molecules might enhance tumor-platelet interaction. We therefore studied binding of sFn monomer to tumor cells in a static microplate adhesion assay and determined the effect of pre-treating tumor cells with sFn on tumor cell-induced thrombocytopenia and experimental metastasis. Soluble fibrin (produced by adding thrombin to FXIII- and plasminogen-free Fg in the presence of Gly-Pro-Arg-Pro-amide (GPRP-NH2) significantly increased platelet adherence to tumor cells. This effect was primarily mediated by the integrins alphaIIb beta3 on the platelet and CD 54 (ICAM-1) on the tumor cells. Platelets adhered to untreated A375 cells (28 +/- 8 platelets/tumor cell) and this was not significantly affected by pre-treatment of the tumor cells with fibrinogen or GPRP-NH2. Although thrombin treatment increased adherence, pre-incubation of the tumor cells with sFn resulted in a further increase in platelet binding to tumor cells. In contrast to untreated tumor cells, intravenous injection of sFn-treated A 375 cells reduced the platelet count in anticoagulated mice, supporting the in vitro finding that sFn enhanced tumor cell-platelet adherence. In a more aggressive model of experimental metastasis, treating tumor cells with sFn enhanced lung seeding by 65% compared to untreated cells. Extrapolation of our data to the clinical situation suggests that coagulation activation, and subsequent increase in circulating Fn monomer, may enhance platelet adhesion to circulating tumor cells and thereby facilitate metastatic spread.

Animals↗