Tumor angiogenesis in node-negative breast carcinomas — relationship with epidermal growth factor receptor,estrogen receptor,and survival

Summary Angiogenesis is essential for tumor growth and metastases. Studies in breast carcinomas suggest that microvessel quantitation as a measure of angiogenesis might be one of the most powerful prognostic tools available. Node negative breast cancer is a particular group for which better prognostic markers would be helpful. We therefore measured microvessel density in a series of well characterised node negative breast carcinomas to evaluate angiogenesis as a prognostic marker and assess its relationship to epidermal growth factor receptor (EGFR) and estrogen receptor (ER), which have previously been reported to be of value. 109 patients with a mean age of 55 years and a median follow-up of 25 months were examined. Vessels were immunohistochemically highlighted using an antibody to platelet endothelial cell adhesion molecule CD31, and microvessel density was quantified using a Chalkley point eyepiece graticule. No significant correlation was observed with patient age, tumor size, grade, ER, or EGFR expression. In a univariate analysis of survival, whereas ER expression was not a significant indicator of either relapse-free (RFS) or overall survival (OS), vascular count (VC) predicted both early RFS and OS (p=0.01 and p=0.028 respectively). Furthermore, in patients with ER positive tumors, a subgroup usually considered to have a good prognosis, there was a significant reduction in RFS and OS if tumors had high VCs (p=0.05 and p=0.002 respectively). A further statistically significant reduction in RFS (p=0.05) was observed for EGFR positive highly vascular tumors. In a Cox proportional hazard model, VC remained a significant prognostic indicator for both RFS and OS (p=0.04 and p=0.01) and conferred a 6.6 and 3.5 times respective increased risk of mortality and relapse. These findings suggest that quantitation of angiogenesis is an independent predictor of survival in node negative breast carcinomas, and due to these high hazard ratios might be more useful than other recently described prognostic markers in selecting patients who would benefit from adjuvant therapy.     

Low levels of basic fibroblast growth factor (bFGF) are associated with a poor prognosis in human breast carcinoma.

It has been suggested that angiogenesis and angiogenic factors may be strong predictors of relapse in patients with breast carcinoma. We measured the levels of the angiogenic peptide basic fibroblast growth factor (bFGF) in 140 breast tumour cytosols using an immunoassay. There were no significant differences in bFGF levels between breast non-malignant lesions and primary carcinomas. In 124 cases with primary breast cancer, we observed an association of low bFGF levels (< 400 pg mg[-1]) with increasing tumour size (P = 0.023) and stage of disease (P = 0.002). bFGF levels did not correlate with other variables, including axillary nodes, hormone receptors, cathepsin D and the serum tumour markers CA15.3 and CEA. With a median follow-up of 44.0 months, breast cancer patients with low levels of bFGF had a significantly shorter disease-free survival (DFS) than patients with elevated bFGF (log-rank, P < 0.0001). In a multivariate analysis of DFS, only bFGF, T-stage and histological grade showed statistical significance. In a parallel evaluation of circulating bFGF, we did not observe a correlation between the serum and tissue bFGF levels in the 29 selected cases with matched determinations. Our results indicate that low bFGF levels in breast carcinoma are an independent prognostic indicator of poor prognosis and disease recurrence.     

Correlation between basic fibroblast growth factor immunostaining of stromal cells and stromelysin-3 mRNA expression in human breast carcinoma.

We examined the localization of basic fibroblast growth factor (bFGF) in a series of human breast carcinomas using immunohistochemistry. Staining was observed in tumour cells in 15 out of 54 (28%) tumours and in the adjacent stroma in 34 out of 54 (63%) tumours examined. No correlation was observed between positive staining of these two compartments. The relationship between bFGF staining and expression of the metalloprotease stromelysin-3, and between bFGF and microvessel density, was examined. A statistically significant correlation (P < 0.003) was observed between bFGF staining of the stromal compartment and high expression of stromelysin-3 (ST-3; MMP-11) metalloprotease mRNA by stromal cells. In contrast, no correlation was observed between bFGF and intratumour microvessel density (IMD). These results raise the possibility that bFGF may be involved in the induction of stromelysin-3 mRNA expression in breast cancer stroma.     

Transcripts for transforming growth factors in human breast cancer: clinical correlates

The levels of mRNA for transforming growth factors (TGF alpha and beta) and the epidermal growth factor receptor (EGFR) were determined in 69 human breast carcinomas and 20 biopsies of non-neoplastic breast tissue by dot blot hybridisation analysis. TGF alpha mRNA was detected in 42% of cancers and 44% of non-neoplastic breast tissue at low levels. TGF beta mRNA was found in all breast cancers and non-neoplastic breast tissues, but the levels of TGF beta mRNA were found to be higher in breast cancers (P = 0.01). EGFR mRNA was detected in 55% of breast cancers and in all non-neoplastic breast tissue tested. The presence of EGFR mRNA was inversely related to oestrogen receptor (ER) status (P = 0.0001). Coexpression of TGF alpha and EGFR was observed in 28% of the carcinomas, and significantly more commonly in ER negative tumours (P = 0.01). No significant relationship was found between histological grade, tumour cellularity or tumour desmoplasia and expression of either the TGFs or of EGFR mRNA. High levels of TGF beta were, however, associated with the absence of lymph node metastases at presentation (P = 0.05). Levels of TGF alpha and beta and EGFR mRNA were analysed in relationship to the relapse-free and overall survival of patients with breast cancer, but none was found to predict significantly the outcome in these patients. Longer clinical follow-up and larger numbers of patients are required to determine whether TGFs will prove a useful marker for prognosis in breast cancer patients.     

Prognostic correlation of basic fibroblast growth factor and vascular endothelial growth factor in 1307 primary breast cancers

This study was designed to investigate the possible relationship between the protein expression of basic fibroblast growth factor (bFGF) and vascular endothelial growth factor (VEGF) with p53 status, breast cancer prognostic factors, metastatic site, and survival after adjuvant therapy. Basic fibroblast growth factor and VEGF expression were determined by enzyme-linked immunosorbent assays in cytosol specimens obtained from 1307 patients with T1-3 primary breast cancer (789 node-negative, 518 node-positive) diagnosed between 1990 and 1997. The median follow-up time was 70 months. Increased bFGF expression was more frequently found in tumors with low VEGF expression (r = -0.286; P = 0.095). Increased bFGF was associated with smaller tumors (P < 0.001), absence of axillary metastasis (P = 0.003), low S-phase fraction (P < 0.001), and longer recurrence-free survival (RFS; P = 0.0038) and overall survival (OS; P = 0.0316). Vascular endothelial growth factor was a prognostic factor for RFS (P < 0.0001) and OS (P < 0.0001) in univariate and multivariate analyses (RFS: 95% CI, 1.1-1.7; P = 0.036; OS: 95% CI, 1.2-2.2; P = 0.002), whereas bFGF expression was not correlated with RFS or OS. Increased VEGF content was correlated with shorter survival after adjuvant endocrine therapy (RFS, P = 0.0004; OS, P = 0.0009). Patients with estrogen receptor-negative disease were excluded from the analysis. Basic fibroblast growth factor was not a prognostic factor after adjuvant systemic therapy, nor was it related to metastatic site. Expression of VEGF is an independent prognostic factor for patients with primary breast cancer. High bFGF expression was related to good prognostic features and longer survival times, but did not add prognostic information in multivariate analysis. The results might implicate that different angiogenic pathways exist in human breast cancer.     

Prognostic and predictive value of epidermal growth factor receptor in recurrent breast cancer.

PURPOSE: The prognostic and predictive value of epidermal growth factor receptor (EGFR) expression was evaluated in patients with recurrent breast cancer. EXPERIMENTAL DESIGN: The immunohistochemical expression of EGFR was analyzed in 241 patients with recurrent breast cancer. RESULTS: EGFR expression was positive in 87 of 241 (36%) patients with recurrent breast cancer, whereas the EGFR expression inversely correlated with the estrogen receptor (ER) status. The patients with positive EGFR expression had a significantly worse postrelapse survival than those with a negative EGFR expression, whereas EGFR expression also had a postrelapse prognostic significance in patients with a positive ER status. A multivariate analysis indicated EGFR expression to be an independently significant factor for postrelapse survival, whereas a multivariate analysis in which the ER status was added to variables indicated that ER status but not EGFR expression to be an independently significant factor. There was a significant difference between positive and negative EGFR expression in the treatment response of 82 patients who received hormonal therapies and 374 patients who received chemotherapies, whereas a multivariate analysis indicated the responses to the first-line treatment and EGFR expression to be independently significant factors for postrelapse survival. CONCLUSIONS: EGFR expression had prognostic significance in recurrent breast cancer, whereas its prognostic value was not independent of the ER status. In addition, the EGFR expression was suggested to be related to the responses to hormonal therapy and chemotherapy, whereas the EGFR expression had an additional prognostic value that was independent of the treatment response.     

Prognostic analysis of tumour angiogenesis, determined by microvessel density and expression of vascular endothelial growth factor, in high-risk primary breast cancer patients treated with high-dose chemotherapy

In contrast to early breast cancer, the prognostic effect of tumour angiogenesis in tumours with advanced axillary spread has been less studied. We retrospectively analysed the effect of microvessel density (MVD) and vascular endothelial growth factor (VEGF) by immunohistochemistry on the outcome of 215 patients treated uniformly within prospective trials of high-dose chemotherapy for 4-9 and >/=10 positive nodes, and followed for a median of 9 (range 3-13) years. Microvessel density was associated with epidermal growth factor receptor (EGFR) expression (P<0.001) and tumour size (P=0.001). Vascular endothelial growth factor overexpression (51% of patients) was associated with overexpression of EGFR (P=0.01) and HER2 (P<0.05), but not with MVD (P=0.3). High MVD was associated with worse relapse-free survival (74 vs 44%, P<0.001) and overall survival (76 vs 44%, P<0.001). Vascular endothelial growth factor overexpression had no effect on outcome. Multivariate analyses showed a prognostic effect of MVD independently of other known prognostic factors in this patient population. In conclusion, tumour angiogenesis, expressed as MVD, is a major independent prognostic factor in breast cancer patients with extensive axillary involvement.     

Epidermal growth factor receptor immunostaining and epidermal growth factor receptor-tyrosine kinase activity in proliferative and neoplastic human endometrium.

Epidermal growth factor receptor (EGFR) expression and EGFR-tyrosine kinase (EGFR-TK) activity were measured in proliferative (n = 12) and neoplastic (n = 31) human endometrium. Immunoreactivity of EGFR was related to clinicopathological features, estrogen receptor (ER) and progesterone receptor (PR) status, and patient outcome. All proliferative and 27 neoplastic specimens expressed the EGFR. Expression of the EGFR was higher in proliferative endometrium than in endometrial cancer (p < 0.0001). ER immunostaining was observed in 19 of the endometrial carcinomas, while PR expression was demonstrated in only 12 neoplastic specimens. EGFR expression was not related to the ER/PR immunostaining in endometrial carcinomas. Clinicopathological features (age, stage, histological type, grade or depth of invasion) and clinical outcome were unrelated to EGFR immunoreactivity. EGFR-TK activity was detected in 29 of 31 endometrial neoplasms with a 9 times higher mean activity in neoplastic than in proliferative endometrial specimens. There was no relationship between the EGFR-TK activity and EGFR immunostaining in human neoplastic endometrium (p = 0.77). A trend towards a poorer outcome of patients with the EGFR-TK activity above 40 pmol/min/mg was observed, but was not statistically significant. These results support the view that the EGFR expression is downregulated in endometrial carcinomas compared to proliferative endometrial specimens.     

Elevated levels of the angiogenic cytokines basic fibroblast growth factor and vascular endothelial growth factor in sera of cancer patients.

The concentration of basic fibroblast growth factor (bFGF) and vascular endothelial growth factor (VEGF) was determined in the serum of 90 untreated and 42 treated metastatic cancer patients, including patients with colorectal, breast, ovarian and renal carcinomas, with an enzyme-linked immunosorbent assay (ELISA). Levels higher than the 95th percentile of the concentrations of a control group, i.e. 7.5 pg ml(-1) for bFGF and 500 pg ml(-1) for VEGF, were identified as ''elevated''. One measurement during follow-up was included into the analysis per patient. For 19 treated patients, consecutive serum samples were analysed. Fifty-seven per cent of all untreated patients had elevated serum levels of one or both angiogenic factors. The fraction of patients with elevated serum levels of bFGF and/or VEGF was similar in the different tumour types. Agreement of bFGF levels and VEGF levels, classified in relation to their respective cut-off values, was present in 67% of all patients. Fifty-eight per cent of the patients with progressive disease during treatment compared with 15% of the patients showing response to treatment (chi-squared test P < 0.05) had elevated bFGF and/or VEGF serum levels. When consecutive serum samples were analysed, two-thirds of the patients showing progressive disease had increasing serum levels of the angiogenic factors compared with less than one-tenth of the patients showing response (chi-squared test P < 0.05). The lack of association between the serum bFGF and VEGF levels and the tumour type may suggest an aspecific host reaction responsible for solid tumour-related angiogenesis. The main determinants of the serum bFGF and VEGF concentration are the progression kinetics of the metastatic carcinomas.     

Markers of angiogenesis and epidermal growth factor receptor signalling in patients with pancreatic and gastroesophageal junction cancer

The epidermal growth factor receptor (EGFR) and angiogenesis are well established targets in anti-cancer therapy. Several targeted anti-cancer therapies are in clinical trials in pancreatic and gastroesophageal (GEJ) cancer. However, many patients do not respond to these targeted therapies and there is therefore an increasing need for biomarkers for selection of patients to these therapies. We investigated the expression of EGFR, vascular endothelial growth factor A (VEGF-A), and VEGF receptor 2 (VEGFR-2) in tumour tissue by immunohistochemistry, and soluble EGFR (sEGFR), soluble VEGFR-2 (sVEGFR-2), basic fibroblast growth factor (bFGF), placental growth factor (PlGF), plasminogen activator inhibitor 1 (PAI-1), and different forms of the urokinase plasminogen activator receptor (uPAR): uPAR (I), uPAR (I-III), and uPAR (I-III)+(II-III) in plasma by quantitative immunoassays in 14 patients with pancreatic and GEJ cancer. We found expression in tumour tissue and the plasma levels to be similar to those found in patients with other tumour types. No correlation was found between the blood levels of soluble receptors and the corresponding tumour tissue levels. We conclude that these markers are present in pancreatic and GEJ cancer patients, and could be investigated further as predictive biomarkers in such patients treated with EGFR or angiogenesis targeted therapies.     

Expression of epidermal growth factor receptor mRNA and protein in primary breast carcinomas

The expression of epidermal growth factor receptor (EGFR) mRNA and protein has been determined in a group of breast carcinomas and compared to oestrogen and progesterone receptor (ER, PgR) status, as well as pathological features. In situ hybridization using a digoxigenin-labelled oligonucleotide probe was applied to formalin-fixed paraffin-embedded sections, and immunohistochemistry was used to determine EGFR protein.EGFR mRNA was detected in 66% of carcinomas with a third having labelling similar to normal breast tissue, 22% heterogeneous weak to strong labelling, and 11% strong labelling. EGFR protein was detected in 36% and these tumours had a strong correlation to lack of ER and high histological grade. The presence of EGFR protein was strongly correlated with more intense labelling for EGFR mRNA (p < 0.0001). This contrasted with normal breast in which both EGFR protein and mRNA were present with varying degrees in both tumours and a normal breast control. The ER-/PgR- carcinomas showed the full range of EGFR mRNA labelling. It is postulated that oestrogen or oestrogen regulated proteins are involved in regulation of EGFR mRNA and protein. In a proportion of tumours lacking steroid receptors regulation is lost, leading to EGFR overexpression.     

bcl-2 in normal human breast and carcinoma, association with oestrogen receptor-positive, epidermal growth factor receptor-negative tumours and in situ cancer.

The role of bcl-2 expression in solid tumours is as yet undefined. It was, therefore, the purpose of this study to investigate expression of bcl-2 protein in 111 human breast carcinomas using immunohistochemistry and the monoclonal antibody bcl-2 124. Expression was then compared with the established indicators of prognosis and biological behaviour in malignant breast disease. No relationship could be observed between bcl-2 and node status, tumour size, differentiation, type or age at excision. However, a strong positive relationship was seen between bcl-2 and oestrogen receptor (ER), with 70 of 88 (80%) bcl-2-positive tumours being ER positive also, compared with seven of 23 (30%) bcl-2-negative tumours being ER positive (P < 0.0001). The converse was found when bcl-2 was compared with epidermal growth factor receptor (EGFR). A strong negative relationship was observed, with 26 of 88 (30%) bcl-2-positive tumours being EGFR positive, compared with 16 of 23 (70%) bcl-2-negative tumours being EGFR positive (P = 0.001), raising the possibility that bcl-2 is an ER-regulated gene. An inverse relationship was also found between bcl-2 and the oncogenes c-erbB-2 and p53. Thus, loss of bcl-2 expression in breast cancer is associated with a range of molecular markers of poor prognosis and may define part of an ER-negative, EGFR-positive phenotype.     

The prognostic significance of transforming growth factors in human breast cancer.

Transforming growth factor alpha (TGF alpha) and Transforming growth factor beta-1 (TGF-beta 1) are growth regulatory for breast cancer cell lines in vitro and several studies have suggested that levels of the receptor for TGF alpha, the epidermal growth factor (EGFR) in tumour biopsies predict relapse and survival. We have examined the prognostic significance of TGF alpha, TGF-beta 1 and EGFR mRNA expression in a series of patients with primary breast cancer with a median follow up period of 60 months. In 167 patients the expression of TGF-beta 1 was inversely correlated with node status (P = 0.065) but not ER status, tumour size or menopausal status. Patients with high levels of TGF-beta 1 had a longer disease free interval with a significantly longer probability of survival at 80 months although the overall relapse free survival was not increased. EGFR mRNA expression was measured in 106 patients and was inversely correlated with ER status (P = 0.018). EGFR levels did not predict for early relapse or survival. TGF alpha mRNA levels were measured in 104 patients, no correlation was seen tumour size, node status, Er status, or clinical outcome.     

Quantitative analysis of basic fibroblast growth factor and vascular endothelial growth factor in human colorectal cancer.

Tumour growth is angiogenesis dependent. Some authors suggest a prognostic role of microvessel count in colorectal cancer. We tested the role of basic fibroblast growth factor (bFGF) and vascular endothelial growth factor (VEGF) in the switch to the angiogenic phenotype in 35 patients with colorectal cancer at different stages of disease. We evaluated the two angiogenic factors, by enzyme-linked immunosorbent assay (ELISA), in tumour, peritumoral mucosa, pathological mesenteric and peripheral blood. We used ten endoscopic intestinal biopsies and ten peripheral blood samples from healthy subjects as control. bFGF was significantly lower in tumour tissues and in peritumoral mucosas than in healthy mucosas, whereas VEGF was up-regulated in tumours but not in peritumoral mucosa. Both angiogenic factors were greatly increased in mesenteric blood. VEGF tumour and serum levels were significantly correlated with the stage of disease. bFGF tumour and serum concentration were not correlated with the stage of disease. The high levels of bFGF in mesenteric blood suggest that this growth factor might be abnormally released from tumour tissue and peritumoral mucosa and could function as an early effector in the switch to the angiogenic phenotype. In contrast, VEGF, whose levels show a significant correlation with the stage of disease, could act in a following step, supporting tumour progression.     

Angiogenic characteristics of circulating and tumoural thrombospondin-1 in breast cancer

In cancer models, thrombospondin-1 (TSP-1) has been shown to inhibit angiogenesis or promote metastasis by increasing adhesion of malignant cells to endothelium. To determine the role of TSP-1 in breast cancer and breast cancer angiogenesis, we have measured TSP-1 in plasma and tumour cytosols and compared levels to established clinicopathological prognostic parameters and intratumoural microvessel density. TSP-1 was measured, by radioimmunoassay, in plasma (pTSP-1) and tumour cytosols (cTSP-1) of women with early breast cancer (EBC) (n=71). pTSP-1 in EBC was compared to pTSP-1 levels in women with advanced breast cancer (ABC) (n=66), normal controls (n=77) and was correlated with prognostic features and microvessel density (MVD) (measured by CD31 immunostaining). cTSP-1 levels were compared to prognostic features and microvessel density. pTSP-1 in women with EBC (median 484, IQR 344-877 ng/ml) and ABC (median 588, IQR 430-952 ng/ml) were elevated when compared to normal controls (median 21, IQR 175-247) (p<0.001). Women with lymph node metastases (n=35) had higher levels of TSP-1 (median 799 ng/ml, IQR 455-943) than women who were node negative (median 343 ng/ml, IQR 267-514) (n=36) (p<0.05). Levels of pTSP-1 in EBC correlated with MVD (R=0.39, p<0.05). Levels of TSP-1 in tumour cytosols of women with EBC (median 1714, IQR 893-5283 ng/ml) correlated with microvessel density (R=0.46, p<0.01). Circulating levels of TSP-1 appear to be a marker of breast cancer aggressiveness and in breast cancer may have a pro-angiogenic rather than anti-angiogenic role.     

Vascular endothelial growth factor, platelet-derived endothelial cell growth factor and angiogenesis in non-small-cell lung cancer

High microvessel density, an indirect measure of angiogenesis, has been shown to correlate with increased tumour size, lymph node involvement and poor prognosis in non-small-cell lung cancer (NSCLC). Tumour cell vascular endothelial growth factor (VEGF) and platelet-derived endothelial cell growth factor (PD-ECGF) expression correlate with angiogenesis and a poor outcome in this disease. In a retrospective study VEGF and PD-ECGF expression and microvessel density were evaluated immunohistochemically in surgically resected specimens (T1-3, N0-2) from 223 patients with operable NSCLC using the VG1, P-GF.44C and JC70 monoclonal antibodies respectively. High VEGF immunoreactivity was seen in 104 (46.6%) and PD-ECGF in 72 (32.3%) cases and both were associated with high vascular grade tumours (P= 0.009 and P= 0.05 respectively). Linear regression analysis revealed a weak positive correlation between VEGF and PD-ECGF expression in cancer cells (r= 0.21; P = 0.002). Co-expression of VEGF and PD-ECGF was not associated with a higher microvessel density than VEGF or PD-ECGF only expressing tumours. Furthermore a proportion of high vascular grade tumours expressed neither growth factor. Univariate analysis revealed tumour size, nodal status, microvessel density and VEGF and PD-ECGF expression as significant prognostic factors. Tumour size (P < 0.02) and microvessel density (P < 0.04) remained significant on multivariate analysis. In conclusion, VEGF and PD-ECGF are important angiogenic growth factors and have prognostic significance in NSCLC. Furthermore the study underlines the prognostic significance of microvessel density in operable NSCLC.     

Serum basic fibroblast growth factor and vascular endothelial growth factor and tumour growth kinetics in advanced colorectal cancer

BACKGROUND:: The development of new microvessels in the surrounding stromais a prerequisite for tumour progression. Basic fibroblast growthfactor (bFGF) and vascular endothelial growth factor (VEGF)are angiogenic factors expressed in a broad range of human tumours.We have measured the concentrations of both cytokines in theserum of patients with advanced colorectal cancer. We questionedwhether these levels are related to the number of tumour sites,the volume of liver and/or lung involvement and the growth kinetics. PATIENTS AND METHODS:: 44 untreated colorectal adenocarcinoma patients who had developedmetastatic and/or recurrent disease were evaluated. Serum levelsof bFGF and VEGF were repeatedly measured using ELISA. The extentof target organ involvement and the kinetics of tumour volumegrowth were determined on consecutive computer tomography (CT)images. RESULTS:: Patients with a tumour volume doubling time of less than 6 monthsshowed a higher bFGF and VEGF serum level than others, independentof the number of sites involved and the extent of the metastaticdisease. CONCLUSIONS:: The data suggest a predictive value of serum bFGF and VEGF levelsfor the progression of disease in patients with untreated metastaticcolorectal cancer. The results corroborate the importance ofangiogenesis in the process of tumour growth. The serum levelsmight prove a useful tool in the quantitication of angiogenesisand might be of valuable information in the decision processof initiating palliative chemotherapy. It will be of considerableimportance to investigate whether the serum bFGF and VEGF levelshave a predictive value on the probability of response to cytotoxictherapy. angiogenesis, colorectal carcinoma, tumour growth, serum bFGF, esrum VEGF     

Overexpression of basic fibroblast growth factor and autocrine stimulation in acute myeloid leukemia

Basic fibroblast growth factor (bFGF) is known to play a critical role in tumorigenesis of solid tumors. The importance of bFGF in hematological malignancies such as acute myeloid leukemia (AML) remains to be elucidated. Therefore, we determined bFGF protein expression by immunohistochemical analyses in bone marrow biopsies of patients with newly diagnosed, untreated AML. The expression of bFGF was significantly increased in AML patients [n = 81; median, 3.0 (interquartile range, 1.8-3.9) arbitrary units (AU)] as compared with controls [n = 18; 1.9 (1.5-2.3) AU]. The degree of bFGF expression did not correlate with microvessel density. bFGF/FGF receptor mRNA and bFGF protein were detected in different AML cell lines. To study autocrine growth stimulation of AML blasts, the AML cell lines HL-60, M-07e, and KG-1 were incubated with bFGF. A significant dose-dependent increase in proliferation and colony formation was observed. These effects were abrogated by the addition of a polyclonal anti-bFGF antibody. In conclusion, increased expression of bFGF in the bone marrow of AML patients seems to play an important role in the pathophysiology of AML by promoting autocrine growth stimulation of leukemic blasts.