Circulating Angiogenesis Regulators in Cancer Patients

Background/Aims

To date, numerous studies have demonstrated that several angiogenesis regulators circulate in the blood and may function as endocrine factors in cancer patients. This review aims to give a comprehensive insight into the possible clinical value of circulating angiogenesis regulators, mainly basic fibroblast growth factor (bFGF), vascular endothelial growth factor (VEGF), and hepatocyte growth factor (HGF), angiogenin, pleiotrophin, thrombospondin (TSP) and endostatin (ES) in cancer patients.

Methods

A computerized (MEDLINE) and a manual search based on the reference lists of the publications were performed to identify articles published on this topic.

Results

In a detailed literature search, approximately 100 publications were found up to the end of 1999. Circulating angiogenic factors such as bFGF, VEGF, HGF and angiogenin have been evaluated not only as diagnostic and/or prognostic factors but also as predictive factors in cancer patients. On the other hand, little is known about the clinical significance of negative regulators. Neither the source nor the mechanism of protein externalization has been clarified in detail.

Conclusions

Although there are no known factors with established clinical utility, circulating angiogenesis regulators may be useful in several situations. They could be used to determine the risk of developing cancer, to screen for early detection, to distinguish benign from malignant disease, and to distinguish between different types of malignancies. In patients with established malignancies such factors might be used to determine prognosis, to predict the response to therapy, and to monitor the clinical course. Further investigations are warranted to assess the specific utility of each factor.

Clinical significance of fibroblast growth factor (FGF) expression in colorectal cancer

In this study, we serologically and pathologically examined the clinical significance of fibroblast growth factor (FGF) expression in patients with colorectal cancer. Serum basic FGF (bFGF) levels in 92 surgical colorectal cancer patients and 31 controls were measured, and the relationship between those levels and clinicopathological factors were examined. Immunohistochemical study was also conducted on specimens from 51 cancer patients, and the association between bFGF staining and serum levels were investigated. An examination of clinicopathological factors revealed significant differences in bFGF levels between stage 0-IIIb and stage IV cancers (P = 0.013). Lymphatic invasion was one factor that differed significantly. Patients with a tumor 30 mm or smaller had a bFGF level of 7.65 ± 1.11 pg/ml while patients with a tumor 31 mm or larger had a bFGF level of 8.53 ± 3.22 pg/ml; significant differences in these bFGF levels were noted (P < 0.05). Patients with a tumor that had no lymphatic invasion (ly0) had a bFGF level of 7.25 ± 0.66 pg/ml, those with a tumor that had minimal lymphatic invasion (ly1) had a bFGF level of 7.99 ± 1.68 pg/ml, and those with a tumor that had moderate lymphatic invasion (ly2) had a bFGF level of 9.17 ± 4.23 pg/ml. bFGF levels differed significantly for tumors with no/minimal lymphatic invasion (ly0-ly1) and those with moderate lymphatic invasion (ly2) (P < 0.0001). Serological examination of bFGF levels during the proliferation of colorectal cancer revealed that moderate lymphatic invasion can be readily distinguished.

Analysis of NF-kappaB signaling pathways by proteomic approaches

NF-kappaB is a transcription factor that plays important roles in the regulation of apoptosis and inflammation as well as innate and adaptive immunity. Consequently, dysregulations in the NF-kappaB activation cascade have been associated with the pathogenesis of several diseases such as cancer, atherosclerosis and rheumatoid arthritis. Although NF-kappaB signaling pathways have been extensively investigated in this context, its varying components and targets are far from being completely elucidated. There is still an urgent need for the detection of novel NF-kappaB target proteins, novel interaction partners and novel regulators in the activation cascade, in particular with regard to its role in the aforementioned diseases. Therefore, several groups have performed different proteomic approaches to further investigate NF-kappaB signal transduction pathways. Most of these studies have been carried out in the area of cancer research; however, there are also several analyses in the field of inflammatory or autoimmune diseases. Furthermore, there have been a number of basic investigations that principally examined binding partners or so far unknown target proteins of NF-kappaB-related proteins. With these approaches, a number of novel and interesting proteins have been found that interfere with NF-kappaB signal transduction and might have an impact on NF-kappaB-related diseases. The results of these studies are summarized and discussed in this review.

FGFR1 amplification drives endocrine therapy resistance and is a therapeutic target in breast cancer

Amplification of fibroblast growth factor receptor 1 (FGFR1) occurs in approximately 10% of breast cancers and is associated with poor prognosis. However, it is uncertain whether overexpression of FGFR1 is causally linked to the poor prognosis of amplified cancers. Here, we show that FGFR1 overexpression is robustly associated with FGFR1 amplification in two independent series of breast cancers. Breast cancer cell lines with FGFR1 overexpression and amplification show enhanced ligand-dependent signaling, with increased activation of the mitogen-activated protein kinase and phosphoinositide 3-kinase-AKT signaling pathways in response to FGF2, but also show basal ligand-independent signaling, and are dependent on FGFR signaling for anchorage-independent growth. FGFR1-amplified cell lines show resistance to 4-hydroxytamoxifen, which is reversed by small interfering RNA silencing of FGFR1, suggesting that FGFR1 overexpression also promotes endocrine therapy resistance. FGFR1 signaling suppresses progesterone receptor (PR) expression in vitro, and likewise, amplified cancers are frequently PR negative, identifying a potential biomarker for FGFR1 activity. Furthermore, we show that amplified cancers have a high proliferative rate assessed by Ki67 staining and that FGFR1 amplification is found in 16% to 27% of luminal B-type breast cancers. Our data suggest that amplification and overexpression of FGFR1 may be a major contributor to poor prognosis in luminal-type breast cancers, driving anchorage-independent proliferation and endocrine therapy resistance.

Do serum angiogenic growth factors provide additional information to that of conventional markers in monitoring the course of metastatic breast cancer?

OBJECTIVE

Our work evaluated the potential role of basic fibroblast growth factor (bFGF) and vascular endothelial growth factor (VEGF) serum levels with respect to that of conventional serum tumour markers, CEA and CA 15-3, in monitoring the course of metastatic breast cancer in 56 female patients treated with cytotoxic chemotherapy.

METHODS

VEGF and bFGF concentrations were determined using a quantitative sandwich enzyme immunoassay technique. The positive predictive value (PPV) of each marker and of marker combinations for different types of clinical response was calculated.

RESULTS

The highest PPV for overall disease control was shown by bFGF (70%), which also showed the highest PPV for both partial response (36.4%) and stable disease (63.2%). CEA showed the highest predictive value for progression (69.2%). A combined increase in CEA and bFGF or VEGF was associated with disease progression in all patients.

CONCLUSIONS

Information provided by angiogenic factor levels seems to be independent of and is possibly complementary to that provided by conventional serum markers. bFGF showed the maximum predictive value for disease control and provided additional information to that obtained from CEA or CA 15-3 evaluation. It could therefore be a promising candidate for monitoring response to chemotherapy in advanced breast cancer.

The antiapoptotic effect of fibroblast growth factor-2 is mediated through nuclear factor-kappaB activation induced via interaction between Akt and IkappaB kinase-beta in breast cancer cells

Fibroblast growth factor-2 (FGF-2) is known for its mitogenic and motogenic effects on breast cancer cells. Here, we demonstrate that FGF-2 is also a potent stimulator of breast cancer cell survival, as it counteracts the apoptotic activity of the C2 ceramide analogue and various chemotherapeutic agents (5-fluorouracil, camptothecin, etoposide) in MCF-7, T47-D and BT-20 cells. The use of pharmacological inhibitors (PD98059, wortmannin, LY294002, SN50) and transfection with negative dominants (IkappaBm, p110(PI3K (phosphoinositide 3-kinase))*DeltaK, AktND) or small interfering RNA targeted against Akt indicated that PI3K/Akt and nuclear factor-kappaB (NF-kappaB), but not p42/p44 MAP-kinases, were required to stimulate FGF-2 antiapoptotic activity. The activation of NF-kappaB was dependent on PI3K/Akt, and using a combination of approaches based on immunoprecipitation, Western blotting and proteomics (two-dimensional electrophoresis and mass spectrometry), we identified the beta form of IkappaB kinase (IKKbeta) as a target of Akt signaling. The selective disruption of IKKbeta using small interfering RNA induced a potent inhibition of Akt-mediated activation of NF-kappaB and cell survival, indicating the functional involvement of IKKbeta in FGF-2 antiapoptotic signaling. Together, these results demonstrate Akt/IKKbeta interaction in NF-kappaB pathways, thereby emphasizing the potential of these proteins as therapeutic targets in breast cancer.

Basic fibroblast growth factor and vascular endothelial growth factor serum levels in breast cancer patients and healthy women: useful as diagnostic tools?

INTRODUCTION

The aim of the present study was to analyze the relationship between the expression of vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) in breast cancer cells and the corresponding serum levels in individual patients. The study also evaluated the potential of serum levels of the two growth factors as diagnostic markers in a case-control study.

METHODS

VEGF expression and bFGF expression were determined in 62 and 63 tumor samples, respectively. Serum VEGF and bFGF levels were determined in 54 and 65 healthy women and in 69 and 73 breast cancer patients, respectively, using a quantitative sandwich enzyme immunoassay technique.

RESULTS

A direct correlation was observed between VEGF expression and bFGF expression in individual tumors (P = 0.001) and between serum levels (P = 0.038) in individual patients, but not between tumor cell expression and the corresponding serum level for either growth factor. Median values of serum levels in healthy women and breast cancer patients were not different for VEGF (P = 0.055), but were significantly different for bFGF (P < 0.001). The receiver operating characteristic curve identified a serum bFGF concentration of 1.0 pg/ml, with 84.9% sensitivity and 63.1% specificity, as the best cut-off value to discriminate between healthy women and breast cancer patients. An age-based subgroup analysis showed that serum values of patients older than 70 years of age mainly contributed to the high accuracy.

CONCLUSIONS

Our data repropose bFGF as a noninvasive diagnostic tool for breast cancer.

High basic fibroblast growth factor levels in nipple aspirate fluid are correlated with breast cancer

PURPOSE

The angiogenic basic fibroblast growth factor (bFGF) and vascular endothelial growth factor are important in malignant breast epithelial growth. Nipple aspirate fluid (NAF) is a physiologic fluid collected noninvasively that contains proteins secreted by the breast ductal epithelium and may contain markers of breast cancer. The purpose of this study was to determine whether high concentrations of bFGF and vascular endothelial growth factor in NAF would be associated with in situ and invasive breast cancer, and whether prostate-specific antigen, a marker in NAF associated with breast cancer, would improve our ability to determine which subjects had the disease.

METHODS

Both bivariate and multivariate analyses were performed to determine the effects of race, menopausal status, bFGF concentration, and prostate-specific antigen on cancer risk. Bivariate analysis was also performed to determine the relationship between vascular endothelial growth factor concentration and cancer risk.

RESULTS

Mean NAF bFGF levels were higher in women with breast cancer than in those without (19.2 vs 1.74 ng/g). Vascular endothelial growth factor was not associated with breast cancer. Race and menopausal status did not significantly affect the relationship between bFGF and cancer risk. bFGF, race, and menopausal status were each independent predictors of breast cancer, with bFGF being the most important. With knowledge of all three variables, the model was 89.9% sensitive and 69.0% specific in predicting which women had breast cancer. Adding prostate-specific antigen increased the sensitivity to 90.9% and the specificity to 83.3%. In subjects with NAF bFGF > 150 ng/g and prostate-specific antigen < 100 ng/g, 94.1% (32/34) of subjects had cancer. For women with NAF prostate-specific antigen > 100 ng/ g and bFGF < 150 ng/g, 90.5% were cancer free.

CONCLUSIONS

bFGF concentration in NAF is directly associated with breast cancer, regardless of race and menopausal status. NAF bFGF may prove helpful in the early detection of breast cancer.

The mitogenic signaling pathway for fibroblast growth factor-2 involves the tyrosine phosphorylation of cyclin D2 in MCF-7 human breast cancer cells

Fibroblast growth factor-2 (FGF-2) is mitogenic for the human breast cancer cell line MCF-7; here we investigate some of the signaling pathways subserving this activity. FGF-2 stimulation of MCF-7 cells resulted in a global increase of intracellular tyrosine phosphorylation of proteins, particularly FGF receptor substrate-2, the protooncogene product Src and the mitogen-activated protein kinase (MAP kinase) cascade. A major increase in the tyrosine phosphorylation of a 30-kDa protein species was also found. This protein was identified as cyclin D2 by mass spectrometry after trypsin digestion. Immunoprecipitation of cyclin D2 and immunoblotting with anti-phosphotyrosine antibodies confirmed that the tyrosine phosphorylation of cyclin D2 was indeed induced by FGF-2 stimulation. In addition, pharmacological inhibition of Src (with herbimycin A and PP2), and of the MAP kinase cascade (with PD98059), confirmed that Src activity is required for the FGF-2-induced phosphorylation of cyclin D2 whereas MAP kinase activity is not. Thus, tyrosine phosphorylation of cyclin D2 may be a key regulatory target for FGF-2 signaling.

Concentration of vascular endothelial growth factor (VEGF) and transforming growth factor-beta1 (TGF-beta1) in the serum of patients with cervical cancer: prediction of response

The aim of this study was to determine the value of the measurement of serum VEGF and TGF-beta1 levels in the diagnosis of cervical cancer and to see whether these levels decrease after treatment for cervical cancer. We measured serum VEGF and TGF-beta1 levels through EIA in patients with CIN (n = 35), and cervical squamous cell cancer (n = 48). We also measured serum VEGF, TGF-beta1, and SCC antigen levels before and after radiotherapy in 13 cervical squamous cell cancer patients. The sizes of the tumors in those patients were measured by a computer tomography scan or magnetic resonance imaging. The serum VEGF levels were different between CIN and cervical cancer groups (P < 0.1), and the serum TGF-beta 1 levels in the cervical cancer group were lower than those in the other groups (P < 0.05). The serum VEGF levels were significantly related to the serum TGF-beta 1 levels in the cervical cancer patients (P < 0.01). In the cervical cancer patients, the decrease in the circulating VEGF levels after receiving radiotherapy was related to the decrease in tumor size (P < 0.01). While the measurement of serum VEGF level is adjuvant in diagnosing cervical cancers, serial serum VEGF level measurements may find a clinical use in the follow-up of women treated for cervical cancer.

Circulating tumor markers in breast cancer: accepted utilities and novel prospects

Detecting and/or monitoring changes in circulating tumor markers might assist in evaluating cancer risk, diagnosis, prognosis, or response to treatment. Several categories of circulating tumor markers have been investigated in breast cancer. These categories include classical tumor-associated antigens, such as CEA and CA 15-3, markers of tumor biology, including markers of angiogenesis, adhesion, and invasion, and antibody response to tumor-associated antigens such as HER2/neu and p53. We used a recently proposed Tumor Marker Utility Grading System to evaluate the use of several circulating tumor markers for different clinical utilities in breast cancer. While there are no tumor markers with established clinical utilities for most uses, tumor-associated antigens can be used for monitoring patients with metastatic disease. In addition, markers of tumor biology such as the circulating extracellular domain of HER2/neu might be useful in determining not only prognosis, but also response to specific treatments. However, further investigations are required to further assess the utility of individual tumor markers for specific clinical uses.

Molecular markers of carcinogenesis

The protein products of oncogenes and tumor suppressor genes play critical roles in the development of many cancers. The expression of a number of these proteins can be detected in extracellular fluids such as blood. This article reviews the literature on the application of methods for the detection of the proteins of oncogenes and tumor suppressor genes in the blood of humans with cancer or at risk for the development of cancer. The detection of these proteins in blood may be useful molecular markers of carcinogenesis that could play an important part in cancer diagnosis, prognosis, and prevention.

Mitogenic activity toward human breast cancer cell line MCF-7 of two bFGFs purified from sera of breast cancer patients: co-operative role of cathepsin D

Mitogenic activity toward MCF-7 cells of two immunoreactive (high-molecular-weight form bFGF, HMW-bFGF; and 16-K bFGF, having the same molecular weight as recombinant bFGF) purified from pooled sera of breast cancer patients by heparin-affinity chromatography and gel filtration was investigated. The mitogenic activity of 16-K bFGF toward the cells was equal to that of recombinant bFGF, whereas the mitogenic effect of HMW-bFGF was weak. Most of the mitogenic activity of these two bFGFs was neutralized by anti-bFGF antibody. Also, the mitogenic activity of both HMW-bFGF and 16-K bFGF was markedly enhanced by aspartyl protease (cathepsin D), which is secreted in excess by breast cancer cells and is responsible for the enzymatic degradation of the extracellular matrix (ECM). By an enzyme immunoassay, we detected cathepsin D-mediated release of recombinant bFGF previously bound to the ECM of MCF-7 cells into the conditioned medium, and also observed cathepsin D-mediated proteolysis of HMW-bFGF to release free 16-K bFGF. These results suggest that 16-K bFGF is the bFGF molecule itself in the blood and that HMW-bFGF is a circulating form of bFGF in blood whose mitogenic activity is regulated by cathepsin D.

Serum concentrations of basic fibroblast growth factor in collagen diseases

BACKGROUND

Basic fibroblast growth factor (bFGF), a cytoplasmic polypeptide growth regulator that induces endothelial cell and fibroblast proliferation, is produced by endothelial cells and skeletal muscle.

OBJECTIVE

We hypothesized that this factor is involved in fibrotic changes in muscle and skin in collagen diseases.

METHODS

The serum level of bFGF was measured in 74 patients with systemic sclerosis, 12 with systemic lupus erythematosus, 33 with dermatomyositis, 13 with Raynaud's disease, and 20 control subjects.

RESULTS

bFGF was undetectable in the serum of normal persons, but detectable levels were found in 31 of 74 patients with systemic sclerosis and 7 of 33 patients with dermatomyositis. Elevated serum bFGF level was correlated with an elevated plasma endothelin level and anticentromere antibody in patients with systemic sclerosis. An elevated serum bFGF level correlated with lung fibrosis and an elevated creatine kinase level in the patients with dermatomyositis.

CONCLUSION

Measurement of the serum bFGF level may be useful to detect vascular damage in patients with systemic sclerosis and muscule fibrosis in patients with dermatomyositis.