Have urinary levels of the angiogenic factors, basic fibroblast growth factor and vascular endothelial growth factor, a prognostic value in childhood acute lymphoblastic leukaemia?

Angiopoietins in the bone marrow microenvironment of acute lymphoblastic leukemia

OBJECTIVE

Angiogenesis have implications in leukemia biology. Angiopoietin 1 (Ang 1) is an angiogenic cytokine which is essential in survival and proliferation of endothelial cells. Angiopoietin 2 (Ang 2) promotes dissociation of pericytes and increases vascular permeability and stromal derived factor 1 alpha (SDF 1α) which is a key player in stem cell traffic in the bone marrow (BM), has stimulating effects on angiogenesis as well. Here, we investigated the role of the leukemic BM microenvironment and specifically, the role of SDF 1α-CXCR4 and Ang 1/Ang 2-Tie 2 axes.

METHODS

Here, Ang 1, Ang 2, and SDF 1α levels were measured in the BM plasma and in supernatants of mesenchymal stem/stromal cells (MSCs) of patients with ALL and compared with those of healthy controls.

RESULTS

The results showed that at diagnosis, BM plasma levels of Ang 1 and SDF 1α were significantly low and Ang 2 was high when compared to control values. Remission induction was associated with an increase in Ang 1/Ang 2 ratio and SDF levels in BM plasma.

DISCUSSION

The results suggest that BM microenvironment and leukemic cell-stroma interaction influences the secretion of Ang 1, 2 and SDF 1α, thus, may affect both angiogenesis, homing and mobilization of leukemic blasts.

Angiogenesis as a treatment target in leukemia

SUMMARY The importance of angiogenesis in the growth and survival of leukemia has been well established and confirmed by several studies. In the last 20 years, several antiangiogenic agents have been used in preclinical and clinical studies of the treatment of leukemia. This review article summarizes the literature focusing on the relationship between angiogenesis and disease progression, and the advantages and limits of the antiangiogenic treatment of leukemia.

Serum vascular endothelial growth factor-a levels during induction therapy in children with acute lymphoblastic leukemia

OBJECTIVE

To evaluate serum vascular endothelial growth factor (VEGF) levels in children with acute lymphoblastic leukemia (ALL) during the induction phase of chemotherapy.

DESIGN

Prospective sudy.

SETTING

Setting: Hospital-based study over 18 months.

PATIENTS

30 children with ALL and 17 healthy age- and sex-matched controls.

INTERVENTION

Serum concentration of VEGF-A-165 isoform (s-VEGF) was measured by enzyme-linked immunoabsorbant assay at diagnosis and at the end of induction chemotherapy.

MAIN OUTCOME MEASURES

s-VEGF was compared with markers of tumor burden. Kinetics of s-VEGF was assessed in response to induction chemotherapy.

RESULTS

Median VEGF was significantly lower in untreated patients than in controls (17.0 vs. 42.6 pg/mL, P=0.004). s-VEGF levels were fairly correlated with WBC count (r=-0.56, P=0.004) and LDH (r=-0.52, P=0.02) at diagnosis. All patients but one were in morphologic remission at the end of induction. Median s-VEGF concentration on day 29/33 was significantly higher than on day 1 (44.2 pg/mL, P=0.009).

CONCLUSIONS

Untreated children with ALL have significantly lower s-VEGF concentration than controls. At the end of the induction therapy, s-VEGF increased to levels similar to controls. The role of ligand-receptor interaction between VEGF and VEGF receptors on leukemia cells needs to be further delineated.To identify the risk factors for scholastic backwardness in children.

What role for angiogenesis in childhood acute lymphoblastic leukaemia?

The role of angiogenesis in acute leukaemia has been discussed since the cloning of the gene of vascular endothelial growth factor (VEGF) from the acute myelogenous leukemia cell line (HL60) and, thereafter, when the first studies reported increased bone marrow vascularity and elevation of angiogenic cytokines in acute lymphoblastic leukaemia (ALL). VEGF and basic fibroblast growth factor (bFGF) are the major proangiogenic cytokines that have been studied, and evaluation of their prognostic impact in childhood ALL has been reported in several studies, though with controversial results. The antiangiogenic response, contributing to the angiogenic balance, has scarcely been reported. The origin of the factors, their prognostic value, and their relevance as good markers of what really happens in the bone marrow are discussed in this paper. The place of antiangiogenic drugs in ALL has to be defined in the global treatment strategy.

Clinical role of bone marrow angiogenesis in childhood acute lymphocytic leukemia

PURPOSE

Vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) are associated with increased angiogenesis, growth, and metastasis in solid tumors. But, until today, the importance of theses factors on leukemia, especially childhood acute lymphocytic leukemia (ALL) has received limited attention. Therefore, this study examined the bone marrow plasma VEGF and bFGF levels in ALL patients and normal controls.

PATIENTS AND METHODS

Bone marrow plasmas at diagnosis from 33 ALL patients (median age 5.9 years; range 1.8-13.9 years) were used for analysis. The bone marrow levels of bFGF and VEGF were determined by enzyme-linked immunosorbent assay (R & D Systems) and compared with the bone marrow levels of 7 healthy control subjects (median age 11.98 years; 6 months -13.6 years).

RESULTS

Average VEGF was higher in relapse ALL (N=7, 216.6 +/- 79.9pg/mL) compared to standard (N=9, 36.8 +/- 12.1pg/mL) (p=0.013) or high risk ALL (N=17, 80.0 +/- 12.2pg/mL) (p=0.023). bFGF levels were also significantly higher in relapse than standard-, or high-risk ALL patients (relapse ALL; 48.6 +/- 15.4pg/mL, standard risk ALL; 18.9 +/- 5.5pg/mL, high risk ALL; 19.0 +/- 3.5pg/mL, normal control; 18.6 +/- 4.0pg/mL) (p=0.003). Three patients with refractory relapse and death had much higher VEGF and bFGF values (VEGF; 420.0 +/- 81.6pg/ mL, bFGF; 85.6 +/- 3.2pg/mL).

CONCLUSION

Our data suggest that the increased levels of VEGF and bFGF in bone marrow may play an important role in prognosis of childhood ALL.

Endostatin variations in childhood acute lymphoblastic leukaemia--comparison with basic fibroblast growth factor and vascular endothelial growth factor

Angiogenic factors such as basic fibroblast growth factor (bFGF) or vascular endothelial growth factor (VEGF) were previously studied in childhood acute lymphoblastic leukaemia (ALL) but little is known concerning the anti-angiogenic response in ALL. At diagnosis, the plasma levels of the anti-angiogenic factor endostatin were significantly higher in 33 children with ALL than in controls (median values 17.7 and 7.6 ng/ml, respectively, p=0.0192) but no relationship was observed with plasma bFGF or VEGF levels. The highest levels were observed in patients with an hyperdiploïd karyotype. Expression of mRNA for collagen XVIII/endostatin in lymphoblasts was detected in 19/24 cases but protein secretion was found only in 14/28 supernatants of cultured lymphoblasts. No direct relationship appeared between secretion of endostatin by lymphoblasts and plasma levels. In addition, endostatin levels remained elevated in remission, suggesting that endostatin could have a stromal origin as well. No prognostic value of plasma endostatin could be assessed. In conclusion, the present data indicate that an anti-angiogenic response is observed in some ALL children, but its physiopathological importance remains to be established.

Leukemia-stimulated bone marrow endothelium promotes leukemia cell survival

Extensive endothelial cell proliferation and marked neovascularization are the most pronounced microenvironmental changes consistently observed in the bone marrow (BM) of patients with acute lymphoblastic leukemia (ALL). It is not known whether ALL cells induce this phenotype and whether they receive critical signals from the tumor-associated BM endothelium. Here, we show that leukemia cells actively stimulate BM endothelium, promote de novo angiogenesis, and induce neovascularization in the leukemic BM. Soluble factors, present in the leukemic BM microenvironment, promote the proliferation, migration, and morphogenesis of BM endothelial cells, which are critical processes in tumor angiogenesis. We also show in vitro that leukemia cells display directional motion towards assembled BM endothelium and following adherence exhibit cell polarization, pseudopodia, and ultrastructural features that suggest the existence of leukemia-endothelium cross-talk. Finally, we show that BM endothelium promotes leukemia cell survival through a mechanism mediated through the anti-apoptotic molecule bcl-2. These studies indicate that ALL cells actively recruit BM endothelium and mediate the leukemia-associated neovascularization observed in ALL. Therefore, disruption of interactions between leukemia cells and BM endothelium may constitute a valid therapeutic strategy.

Angiogenic factors may have a different prognostic role in adult acute lymphoblastic leukemia

Angiogenesis plays an important role in solid tumors and hematologic malignancies. The prognostic significance of angiogenic factors in adult acute lymphoblastic leukemia (ALL) remains ambiguous. We therefore analyzed the impact of angiogenic factor levels on overall survival of newly diagnosed adult ALL patients. Plasma levels of vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), interleukin-1 receptor alpha (IL-1Ralpha), IL-6, IL-8, VEGF receptors VEGFR1 and VEGFR2, and thrombopoietin (TPO) were measured in plasma samples of 95 patients by enzyme-linked immunosorbent assay (ELISA). In a univariate Cox proportional hazards model, higher levels of IL-1Ralpha, IL-8, VEGFR1, and VEGFR2 were predictive of poor survival. In contrast, higher levels of VEGF were predictive of longer survival, and higher levels of bFGF suggested a similar trend (P = .09). The multivariate model simultaneously included VEGF (relative risk [RR] for death, 8.01; P = .001 for levels less than or equal to 19.5 pg/mL), IL-1Ralpha (RR, 5.12; P = .007 for levels greater than 373 pg/mL), and VEGFR2 (RR, 4.01; P = .04 for levels greater than 8222 pg/mL) as independent factors for survival. Of interest is the association of high levels of VEGF with good prognosis and higher levels of VEGF receptors with poor outcome. These data reflect the complexity by which angiogenic factors may affect the clinical behavior of patients with ALL, and this complexity should be considered in any therapeutic strategy incorporating antiangiogenic agents.