Angiogenesis and lymphangiogenesis are downregulated in primary breast cancer.

BACKGROUND: Angiogenesis and lymphangiogenesis are considered to play key roles in tumour growth, progression and metastasis. However, targeting tumour angiogenesis in clinical trials showed only modest efficacy. We therefore scrutinised the concept of tumour angiogenesis and lymphangiogenesis by analysing the expression of crucial markers involved in these processes in primary breast cancer. METHODS: We analysed the expression of angiogenic, lymphangiogenic or antiangiogenic factors, their respective receptors and specific markers for endothelial and lymphendothelial cells by quantitative real-time RT-PCR in primary breast cancer and compared the expression profiles to non-cancerous, tumour-adjacent tissues and breast tissues from healthy women. RESULTS: We found decreased mRNA amounts of major angiogenic and lymphangiogenic factors in tumour compared to healthy tissues, whereas antiangiogenic factors were upregulated. Concomitantly, angiogenic and lymphangiogenic receptors were downregulated in breast tumours. This antiangiogenic, antilymphangiogenic microenvironment was even more pronounced in aggressive tumours and accompanied by reduced amounts of endothelial and lymphatic endothelial cell markers. CONCLUSION: Primary breast tumours are not a site of highly active angiogenesis and lymphangiogenesis. Selection for tumour cells that survive with minimal vascular supply may account for this observation in clinical apparent tumours.

Circulating endothelial cells and angiogenic serum factors during neoadjuvant chemotherapy of primary breast cancer.

Circulating endothelial cells (CECs) as well as bone-marrow-derived endothelial precursor cells (EPC) play an important role in neovascularisation and tumour growth. To study the impact of neoadjuvant chemotherapy on the amounts of CEC and their precursor cells, mature CEC and their progenitors were quantified by flow cytometry in peripheral blood of breast cancer patients during anthracycline and/or taxane based neoadjuvant chemotherapy and subsequent surgery in comparison to age-matched healthy controls. Cell numbers were tested for correlation with serum levels of angiopoietin-2, erythropoietin, endostatin, endoglin, VEGF and sVCAM-1 as well as clinical and pathological features of breast cancer disease. Circulating endothelial cells were significantly elevated in breast cancer patients and decreased during chemotherapy, whereas EPC (CD34+/VEGFR-2+) as well as their progenitor cell population CD133+/CD34+ and the population of CD34+ stem cells increased. Concomitantly with the increase of progenitor cells an increase of VEGF, erythropoietin and angiopoietin-2 was observed. These data suggest that chemotherapy can only reduce the amounts of mature CEC, probably reflecting detached cells from tumour vessels, whereas the EPC and their progenitors are mobilised by chemotherapy. Since this mobilisation of EPC may contribute to tumour neovascularisation an early antiangiogenic therapy in combination with chemotherapy could be beneficial for the success of cancer therapy.

Real-time PCR of CD146 mRNA in peripheral blood enables the relative quantification of circulating endothelial cells and is an indicator of angiogenesis.

Angiogenesis is a fundamental process in tumour growth and metastatic dissemination. Possible surrogate markers for tumour angiogenesis are the amounts of circulating endothelial cells (CEC) in peripheral blood and the plasma concentration of vascular endothelial growth factor (VEGF). We tested the suitability of real-time PCR for CD146, an endothelial cell-specific antigen, to quantify CEC numbers in comparison to a flow cytometry quantification. Real-time PCR of CD146 mRNA showed high sensitivity and linearity for the quantification of cultivated primary endothelial cells added in different amounts to blood samples. Circulating endothelial cell numbers were quantified in peripheral blood samples of breast cancer patients and healthy controls by four-colour flow cytometry analysis and CD146 real-time PCR, and VEGF plasma concentrations were measured by ELISA. The amounts of CEC detected with both methods correlated significantly and CEC numbers were significantly increased in newly diagnosed breast cancer patients compared to healthy controls. Vascular endothelial growth factor concentrations correlated significantly with CEC numbers, but there was no significant difference in VEGF levels between breast cancer patients and healthy controls indicating that VEGF plasma levels cannot be used as surrogate marker for tumour angiogenesis. Taken together, the quantification of CEC by CD146 real-time PCR showed equivalent results to the flow cytometry analysis. Thus, CD146 real-time PCR may be an easy and reliable approach to quantify CEC in peripheral blood samples and could facilitate the integration of CEC measurements in clinical studies exploring the efficacy of antiangiogenic therapies.

Hydrostatic pressure induces apoptosis in the human leukaemic T-cell line Jurkat via the mitochondrial pathway.

We investigated the effect of pressure levels ranging from 80 to 500 bar on the proliferative capacity and viability of Jurkat leukaemic T cells. Pressurization at 360 bar induced apoptotic cell death as shown by apoptotic morphology after Hoechst staining, DNA fragmentation in the TdT-mediated dUTP nick end labelling-assay and cleavage of several caspase substrates. Cell death could be prevented by the general caspase inhibitor zVAD-fmk. Breakdown of the mitochondrial membrane potential and the release of cytochrome c provided strong evidence for an involvement of the mitochondrial pathway, whereas a central role of the death receptor pathway was excluded because caspase-8 was not significantly activated. Pressure incubation led to calcium influx after 5 min, and we hypothesize that calcium influx could be the primary trigger for pressure-induced apoptosis.

Molecular aspects of anti-inflammatory action of G-CSF.

Granulocyte colony-stimulating factor (G-CSF) is a cytokine which stimulates the production of neutrophils in the bone marrow and modulates cellular functions of mature neutrophils. Besides neutrophils and their precursors, monocytes are direct target cells of G-CSF action. G-CSF influences monocyte functions in an anti-inflammatory way: The stimulation of monocytes with G-CSF results in an attenuation of LPS-induced release of IL-1beta, TNF-alpha, IL-12 and IL-18. G-CSF exerts its biological functions on neutrophils and monocytes via membrane-bound receptors. Seven different human G-CSF receptor isoforms have been described which are generated by alternative splicing. The physiologic roles of these isoforms and the expression pattern on various cell types are still unknown. The signal transduction pathway of G-CSF receptors involves the activation of JAK tyrosine kinases and STAT transcription factors and the ras/mitogen-activated protein kinase pathway.

Mistletoe lectin-1 increases tumor necrosis factor-alpha release in lipopolysaccharide-stimulated whole blood via inhibition of interleukin-10 production.

We examined the immunomodulatory properties of the mistletoe preparation Lektinol (standardized for mistletoe lectin-1) and recombinant mistletoe lectin-1 (rML-1) in vitro by assessing alterations in the cytokine response of human whole blood. Lektinol or rML-1 alone did not induce any cytokine release in unstimulated whole blood. However, the lipopolysaccharide (LPS)-induced release of tumor necrosis factor (TNF)-alpha was increased, and the secretion of interleukin (IL)-10 was reduced by Lektinol at a mistletoe lectin-1 (ML-1) concentration of 0.5 to 5 ng/ml, whereas the LPS-induced secretion of IL-1 beta, IL-6, IL-12, and interferon-gamma was not affected. Lektinol did not alter the initial phase of TNF-alpha production but sustained TNF-alpha levels longer than in the LPS controls. Recombinant ML-1, but not the recombinant B-chain alone, also increased TNF-alpha release and decreased IL-10 release. We propose that the increase in TNF-alpha release is due to a specific inhibition of IL-10 release by Lektinol. This conclusion is based on the observation that blocking of endogenously formed IL-10 by a neutralizing antibody results in a similar increase of TNF-alpha in the late production phase after LPS stimulation. This hypothesis was also corroborated by the finding that when endogenously formed IL-10 was blocked, Lektinol could no longer increase TNF-alpha release. These results indicate that Lektinol modulates the cytokine response of human whole blood to LPS in a proinflammatory fashion, which can be attributed to ML-1.

Human monocytes express functional receptors for granulocyte colony-stimulating factor that mediate suppression of monokines and interferon-gamma.

In a double-blind, placebo-controlled, randomized study, 10 healthy men received either a single dose of 480 microg granulocyte colony-stimulating factor (G-CSF) or saline. Blood taken from the volunteers was stimulated with 10 microg/mL endotoxin and released cytokines were measured by enzyme-linked immunosorbent assay. Expression of G-CSF receptors on leukocytes was examined by flow cytometry and reverse transcriptase-polymerase chain reaction. Functional activity of these receptors was tested by challenging isolated leukocyte populations to release cytokines with endotoxin in the presence of G-CSF. The G-CSF treatment attenuated the release of the proinflammatory cytokines tumor necrosis factor (TNF)-alpha, interleukin (IL)-12, IL-1beta, and interferon (IFN)-gamma in ex vivo lipopolysaccharide (LPS)-stimulated whole blood. In blood from untreated volunteers the presence of G-CSF in vitro also attenuated the LPS-stimulated release of these cytokines. G-CSF in vitro also attenuated TNF-alpha release from elutriation-purified monocytes. In the presence of 10 ng/mL recombinant TNF-alpha, the attenuation of LPS-inducible IFN-gamma release by G-CSF was blunted in whole blood. However, G-CSF had no such effect on IFN-gamma release from isolated lymphocytes stimulated with anti-CD3 or a combination of TNF-alpha and IL-12. G-CSF receptor expression was detected in human neutrophils and monocytes but not in lymphocytes by means of RT-PCR as well as flow cytometry. These results indicate that G-CSF receptors expressed on monocytes are functional in modulating monokine release. We conclude that the attenuation of IFN-gamma release from lymphocytes is not a direct effect of G-CSF on these cells but is rather due to the inhibition of monocytic IL-12 and TNF-alpha release by G-CSF. (Blood. 2000;95:270-276)

Inhibition of cyclooxygenase-1 and -2 by R(-)- and S(+)-ibuprofen.

Since the discovery of a cytokine-inducible isozyme of cyclooxygenase (COX-2), its pharmacologic inhibition has been the subject of recent investigations. These include tests for the selectivity of known nonsteroidal antiinflammatory drugs (NSAIDs) on the constitutive enzyme of cyclooxygenase (COX-1) compared with the inducible enzyme COX-2. The interesting question arose whether the R(-)- and S(+)-isomers exhibited different inhibitory potencies for ibuprofen. Results with isolated COX-1 and COX-2 isozymes confirmed the known higher efficacy of S(+)-compared with R(-)-ibuprofen. The R(-)-isomer is almost inactive in inhibiting COX-2. In addition, the S(+) form has a several times lower potency with COX-2 than with COX-1. These data were evaluated in platelets containing mainly the constitutive COX-1, with interleukin-1, pretreated, rat mesangial cells which almost exclusively express COX-2.