The effects of adrenomedullin overexpression in breast tumor cells

BACKGROUND

Adrenomedullin is a secreted peptide hormone with multiple activities. Several reports have indicated that adrenomedullin may be involved in tumor survival, but this has not been directly shown. Here we evaluate the in vitro and in vivo effects of adrenomedullin overexpression in human breast cancer cells.

METHODS

The human breast cancer cell lines T47D and MCF7, both of which express low basal levels of adrenomedullin, were stably transfected with an expression construct that contained the coding region of the human adrenomedullin gene or with empty expression vector. Properties of the transfected cells were assessed by proliferation and apoptosis assays, in vitro and in vivo angiogenesis assays, cell migration experiments, and xenograft implants. The effect of synthetic adrenomedullin on human ovarian (ECV) cancer cell motility was also tested. Western blot analysis was used to compare expression levels of several genes whose products are associated with cell growth and regulation of apoptosis.

RESULTS

T47D and MCF7 cells transfected with the adrenomedullin construct both expressed high levels of adrenomedullin mRNA and protein. Compared with cells transfected with empty vector, cells that overexpressed adrenomedullin displayed a more pleiotropic morphology, an increased angiogenic potential both in vitro and in vivo, and less apoptosis after serum deprivation. T47D and MCF7 cells did not display measurable motility, but ECV ovarian cancer cells treated with synthetic adrenomedullin were more motile than saline-treated ECV cells. Adrenomedullin-overexpressing T47D cells had higher levels of proteins involved in oncogenic signal transduction pathways (such as Ras, Raf, PKC, and MAPKp49) and lower levels of pro-apoptotic proteins (such as Bax, Bid, and caspase 8) than T47D cells transfected with empty vector. In a preliminary in vivo experiment, three of 10 nude mice injected with adrenomedullin-overexpressing T47D cells developed xenograft tumors, whereas none of the 10 nude mice injected with cells carrying the empty plasmid developed tumors.

CONCLUSIONS

These results further support the role of adrenomedullin as a survival factor for tumors. Development of physiologically efficient inhibitors of adrenomedullin may prove useful in the clinical management of cancer.

[Indocyanine green angiography in choroid metastases]

BACKGROUND

Up to now the diagnosis of choroidal tumors was mainly based on ophthalmoscopy and ultrasound examination. Indocyanine green angiography allows the identification of vascular patterns in these tumors, which could be helpful in the differential diagnosis. The aim of the study was to characterize the staining patterns of choroidal metastases.

METHODS

In the years 1996-2000 we performed ICG-A of 15 choroidal metastasis using the scanning laser ophthalmoscope from Rodenstock. The mean tumor height was 3.7 mm (2.0-9.0). These angiographies were compared to the angiographies of 38 choroidal malignant melanomas with a mean height of 3.6 mm (1.4-6-6).

RESULTS

All metastases showed a blockage of the background staining and a patchy staining of the tumor surface. Intratumoral vessels could be detected in 13% of all cases of metastases. The choroidal melanomas examined showed a blockage of the background staining in all cases and tumor vessels in 89%.

CONCLUSION

The angiographic picture of the metastatic lesions was characteristic. Intratumoral vessels could not be detected using ICG-A. Most of the metastases showed a patchy staining of the tumor surface.

Preferential topography of proteins regulating vascularization and apoptosis in a MX1 xenotransplant after treatment with hypoxia, hyperthermia, ifosfamide, and irradiation

The MX1 xenotransplant growing in nude mice was used as a model for estrogen- and progesterone-receptor-negative breast cancer. The effects of different therapeutic regimens-combinations of hyperthermia, chemotherapy, and irradiation-on the expression of proteins playing a role in tumor vascularization and apoptosis were investigated. Additionally, MX-1 tumors were exposed to hypoxia to investigate changes in protein expression related to angiogenesis. This is of particular importance with respect to antiangiogenic therapies that may be combined with the treatments mentioned before. Endothelial and adhesion factors, extracellular matrix (ECM) factors, apoptosis-regulating factors, and neuronal factors were examined by immunohistochemical techniques. Concerning vascularization, the most prominent changes were seen in the expression of vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF), which increased strongly after hypoxia. The other cytokines, adhesion and ECM molecules, were either little affected or unaffected by the therapy. At the ultrastructural level, the walls of the tumor vessels are of the sinusoidal type, possessing many fenestrations. With regard to the second focus of this investigation, apoptosis, tumor cells again exerted the strongest differences after hypoxia where c-myc was clearly enhanced, whereas the effects on p53, bcl-2, and CD95 were extremely weak or not detectable. Furthermore, the neurotransmitter somatostatin, a possible "external" regulator of apoptosis, did not show treatment-related changes. In summary, it was shown that 1) within the group of apoptosis-regulating proteins c-myc was particularly affected by hypoxia, indicating a possible role for an activation-induced pathway of apoptosis in this context; 2) minor changes seen after treatment combined with hyperthermia point to a more acute vascular reaction (=dilatation), causing an increase of tissue pO2 rather than angiogenesis; and 3) the concentrations of the angiogenic factors VEGF and bFGF rose strongly under hypoxia, thereby possibly exerting counterproductive effects to antiangiogenic therapy but not to thermochemotherapy or irradiation. This supports the concept of a combined antiangiogenic, hyperthermia, chemo- and irradiation therapy.

Evidence of a bi-phasic effect of thrombospondin-1 on angiogenesis

Contradictory results have been reported regarding the association between vascularity (used as an index of angiogenesis) and thrombospondin-1 (TSP-1) in human tumours. In previous studies, the reported association was based on the estimated average TSP-1 value per tumour, with a sufficient number of specimens collectively analysed per tumour type. Given the extent of intra-tumour heterogeneity, we determined the association between TSP-1 and vascularity within individual specimens, based on the average values of TSP-1 and vascularity in 10-20 pre-selected areas per tumour. Cells expressing TSP-1 mRNA were visualised by in situ hybridisation and quantified by point counting. Vascularity was quantified by point counting and vessel density of von Willebrand Factor-positive vessels. In 10 ductal breast carcinomas, a direct correlation between TSP-1 and vascularity was found in 4 tumours, no correlation in 3 and an inverse correlation in 3. The effect of TSP-1 on endothelial cell migration in vitro was assessed in the Boyden chamber assay. TSP-1 stimulated cell migration at low concentrations (0.1-10 microg/ml) and was inhibitory at high concentrations (25-100 microg/ml). These results suggest that TSP-1 may elicit a concentration-dependent, bi-phasic, effect on angiogenesis.

Cilengitide targeting of alpha(v)beta(3) integrin receptor synergizes with radioimmunotherapy to increase efficacy and apoptosis in breast cancer xenografts

Although metastatic breast cancer is responsive to radioimmunotherapy (RIT), a systemic targeted radiation modality, complete and permanent remissions are not typical with single-modality treatment. Antiangiogenic agents, which target normal, proliferating endothelial cells, have the potential to provide relatively nontoxic continuous inhibition of tumor growth by blocking new blood vessel growth and may synergize with RIT to increase efficacy. This study was designed to determine whether, and how, the cyclic Arg-Gly-Asp peptide Cilengitide (EMD 121974), which targets the alpha(v)beta(3) integrin receptor expressed on neovasculature, could increase systemic RIT efficacy of therapy in a human breast cancer tumor model having mutant p53 and expressing bcl-2. HBT 3477 breast cancer tumor response in nude mice was compared between groups of untreated mice (n = 24), Cilengitide-treated mice (n = 18), RIT (200-260 mu Ci (90)Y-labeled 1,4,7,10-tetraazacyclododecane-N,N',N",N"'-tetraacetic acid (DOTA)-peptide ChL6; n = 46), and combined modality RIT (CMRIT) using RIT and six doses of Cilengitide (250 microg/dose; n = 41). Tumor size, survival, body weight, and blood counts were monitored for efficacy and toxicity of therapy. To clarify the mechanism of synergistic effect, tumors were evaluated at selected time points through 6 days for apoptosis, proliferation, and microvessel density. Cilengitide alone did not alter tumor growth when compared with untreated mice, but CMRIT with Cilengitide increased efficacy of treatment, with the cure rate for mice that received 260 mu Ci RIT increasing from 15 to 53% (P = 0.011). Lower-dose RIT (200 mu Ci) combined with Cilengitide resulted in less increase in cures (36 compared with 25% for RIT alone; P = 0.514). Combined analysis for high- and low-dose groups demonstrated increased efficacy of CMRIT (P = 0.020). Analysis of tumors from CMRIT mice indicated significantly increased apoptosis of tumor and endothelial cells 5 days after RIT compared with tumors from mice given RIT alone. Proliferation was decreased in CMRIT tumors compared with RIT tumors at 6 days (ANOVA, P < 0.05). Microvessel density in tumors from RIT and CMRIT mice was not different. No increased toxicity attributable to Cilengitide was observed based upon pooled blood sample and no statistical increase in mortality. In conclusion, CMRIT, combining Cilengitide and RIT, significantly increased the efficacy of therapy and increased apoptosis compared with single-modality therapy with either agent, in an aggressive, well-studied breast cancer model. The enhanced therapeutic synergy is of particular note, having been achieved without additional toxicity.

Antiangiogenic and antitumor effects of a protein kinase Cbeta inhibitor in human breast cancer and ovarian cancer xenografts

In cell culture, the compound 317615 2HCl, a potent inhibitor of VEGF-stimulated HUVEC proliferation, was not very effective against MX-1 breast cancer cells (IC50= 8.1 microM) or SKOV-3 ovarian carcinoma cells (IC50 = 9.5 microM). Exposure to combinations of paclitaxel or carboplatin and 317615 x 2HCl with MX-1 cells in culture resulted in cell survival that reflected primarily additivity of the two agents. Exposure of SKOV-3 cells to paclitaxel or carboplatin along with 317615 2HCl resulted in cell survivals that reflected additivity of 317615 x 2HCl with paclitaxel and greater-than-additive cytotoxicity with carboplatin. Administration of 317615 x 2HCI orally twice daily to nude mice bearing subcutaneous MX-1 tumors or SKOV-3 tumors resulted in a decreased number of intratumoral vessels as determined by CD31 and CD105 staining with decreases of 35% and 43% in MX-1 tumors and 60% and 75% in SKOV-3 tumors, respectively. 317615 x 2HCl was an active antitumor agent against the MX-1 xenograft and increased the tumor growth delay produced by paclitaxel by 1.7-fold and the tumor growth delay produced by carboplatin by 3.8-fold. Administration of 317615 x 2HCl also increased the tumor growth delay produced by fractionated radiation therapy in the MX-1 tumor. Treatment with 317615 x 2HCl alone increased the lifespan of animals bearing intraperitoneal SKOV-3 xenografts by 1.9 fold compared with untreated control animals. The combination of paclitaxel and 317615 x 2HCl resulted in 100% 120-day survival of SKOV-3 bearing animals. Administration of 317615 x 2HCl along with carboplatin to animals bearing the SKOV-3 tumor produced a 1.8-fold increase in lifespan compared with carboplatin alone. 317615 x 2HCl is a promising new antiangiogenic agent that is in early phase clinical testing.

Angiogenesis, thrombospondin, and ductal carcinoma in situ of the breast

Angiogenesis, the growth of new vessels from existing vasculature, plays an essential role in tumour development. The process involves interaction between a variety of cells, growth factors, and components of the extracellular matrix, regulated by pro-angiogenic and anti-angiogenic factors. This review profiles these factors, outlines the available methods for measuring new vessel formation, and discusses the importance of angiogenesis in breast cancer, with emphasis on ductal carcinoma in situ.

In vitro pharmacological characterizations of the anti-angiogenic and anti-tumor cell migration properties mediated by microtubule-affecting drugs, with special emphasis on the organization of the actin cytoskeleton

The aim of the present work is to investigate whether microtubule-affecting drugs including vincristine, vinblastine, vindesine and vinorelbine are able to produce an anti-angiogenic effect at non-cytotoxic doses in the same way of taxol. The cytotoxic effects were determined by means of the colorimetric MTT assay, and the anti-angiogenic effects on HUVEC cells growing on Matrigel and forming capillary networks. Sixteen additional drugs (camptothecin, SN38, topothecan, adriamycin, daunomycin, etoposide, bleomycin, melphalan, mitomycin C, TNP-470, cisplatin, carboplatin, 5-fluorouracil, methotrexate, suramin and batimastat) were used as control in order to test the specificity of the microtubule-affecting drug effects. We also investigated by means of videomicroscopy whether microtubule-affecting drugs could produce anti-migratory effects at non-cytotoxic doses on tumor cells. Finally, we used computer-assisted fluorescence microscopy to characterize the influence of microtubule-affecting drugs on the polymerization/depolymerization dynamics of the actin cytoskeleton in tumor cells. Our results show that taxol, vincristine and vindesine behave similarly in their ability to reduce the capillary network formation by HUVEC cells cultured on Matrigel. These anti-angiogenic effects appear at non-cytotoxic concentrations. In contrast, vinblastine and vinorelbine produce apparent anti-angiogenic effects by direct cytotoxicity. Microtubule-affecting agents are also able to significantly reduce the level of migration of tumor cells at non-cytotoxic concentrations, some of these effects may occur via modifications to the actin cytoskeleton organization. Several types of microtubule-affecting agents could be used as anti-angiogenic agents by administering them at non-cytotoxic concentrations, and some microtubule-affecting agents abandoned in pharmacological assays could turn out to be potent anti-migratory drugs acting on tumor cells, though without being too cytotoxic.

Morphine stimulates angiogenesis by activating proangiogenic and survival-promoting signaling and promotes breast tumor growth

Morphine is used to treat pain in several medical conditions including cancer. Here we show that morphine, in a concentration typical of that observed in patients' blood, stimulates human microvascular endothelial cell proliferation and angiogenesis in vitro and in vivo. It does so by activating mitogen-activated protein kinase/extracellular signal-regulated kinase phosphorylation via Gi/Go-coupled G protein receptors and nitric oxide in these microvascular endothelial cells. Other contributing effects of morphine include activation of the survival signal PKB/Akt, inhibition of apoptosis, and promotion of cell cycle progression by increasing cyclin D1. Consistent with these effects, morphine in clinically relevant doses promotes tumor neovascularization in a human breast tumor xenograft model in mice leading to increased tumor progression. These results indicate that clinical use of morphine could potentially be harmful in patients with angiogenesis-dependent cancers.

Prognostic importance of tumor angiogenesis in breast carcinoma with adjuvant chemotherapy

Tumor angiogenesis is believed to be related to prognostic factors involved in tumor development and metastasis. Using immunohistochemical methods, we evaluated tumor angiogenesis in 42 early invasive breast cancer patients (T1-2, NO-1-2, M0). Four patients received tamoxifen, 25 patients received CAF or CA, and 15 patients received CMF as adjuvant therapy. The median follow-up was 47 (range 24-119) months. Ten patients (43.5%) in the node-positive group and 2 patients (10.5%) in the node-negative group relapsed (p = 0.019). The mean microvessel count (MVC) was 60.3 3.05 per 200x field (range: 16-95). MVCs of postmenopausal and premenopausal patients were 50.13 +/- 5.74 and 68.64 +/- 4.11, respectively, in the axillary lymph node (ALN)-negative patient group (p = 0.04). Staining was moderate to strong in 13 (68%) ALN-negative and in 17 (74%) ALN-positive patients (p > 0.05), and was also moderate to strong in 82% of premenopausal patients and in 50% of postmenopausal patients (p = 0.037). There was no significant relationship between angiogenesis and p53, nor was angiogenesis significantly associated with the patient ER status and tumor size. No significant correlations were found between OS/DFS and Factor VIII staining or p53 (log rank test, p > 0.05). Of all ALN-negative patients with increased angiogenesis, one patient of the CMF group relapsed, but no recurrence occurred in patients undergoing anthracycline-based chemotherapy (p > 0.05). On the other hand, of all ALN-positive patients with increased angiogenesis, 5/14 patients treated with anthracylcine and 2/2 CMF-treated patients relapsed (p = 0.175). Despite the statistical insignificance, anthracycline-based adjuvant chemotherapy appears to be more effective than CMF as regards relapse prevention particularly in early ALN-positive breast cancer patients with increased angiogenesis. Additional studies are necessary to demonstrate the clinical importance of angiogenesis.

A tumor-homing peptide with a targeting specificity related to lymphatic vessels

Blood vessels of tumors carry specific markers that are usually angiogenesis-related. We previously used phage-displayed peptide libraries in vivo to identify peptides that home to tumors through the circulation and that specifically bind to the endothelia of tumor blood vessels. Here we devised a phage screening procedure that would favor tumor-homing to targets that are accessible to circulating phage, but are not blood vessels. Screening on MDA-MB-435 breast carcinoma xenografts yielded multiple copies of a phage that displays a cyclic 9-amino-acid peptide, LyP-1. Homing and binding to tumor-derived cell suspensions indicated that LyP-1 also recognizes an osteosarcoma xenograft, and spontaneous prostate and breast cancers in transgenic mice, but not two other tumor xenografts. Fluorescein-labeled LyP-1 peptide was detected in tumor structures that were positive for three lymphatic endothelial markers and negative for three blood vessel markers. LyP-1 accumulated in the nuclei of the putative lymphatic cells, and in the nuclei of tumor cells. These results suggest that tumor lymphatics carry specific markers and that it may be possible to specifically target therapies into tumor lymphatics.

MRI-guided diffuse optical spectroscopy of malignant and benign breast lesions

We present the clinical implementation of a novel hybrid system that combines magnetic resonance imaging (MRI) and near-infrared (NIR) optical measurements for the noninvasive study of breast cancer in vivo. Fourteen patients were studied with a MR-NIR prototype imager and spectrometer. A diffuse optical tomographic scheme employed the MR images as a priori information to implement an image-guided NIR localized spectroscopic scheme. All patients who entered the study also underwent gadolinium-enhanced MRI and biopsy so that the optical findings were cross-validated with MR readings and histopathology. The technique quantified the oxy- and deoxyhemoglobin of five malignant and nine benign breast lesions in vivo. Breast cancers were found with decreased oxygen saturation and higher blood concentration than most benign lesions. The average hemoglobin concentration ([H]) of cancers was 0.130+/-0.100 mM, and the average hemoglobin saturation (Y) was 60+/-9% compared to [H]=0.018+/-0.005 mM and Y=69+/-6% of background tissue. Fibroadenomas exhibited high hemoglobin concentration [H]=0.060+/-0.010 mM and mild decrease in oxygen saturation Y=67+/-2%. Cysts and other normal lesions were easily differentiated based on intrinsic contrast information. This novel optical technology can be a significant add-on in MR examinations and can be used to characterize functional parameters of cancers with diagnostic and treatment prognosis potential. It is foreseen that the technique can play a major role in functional activation studies of brain and muscle as well.

Identification of angiogenesis in primary breast carcinoma according to the image analysis

Tumor angiogenesis may be an independent prognostic factor for breast cancer survival. However, we can get the angiogenic property of the breast cancer only after the removal of breast tissue. To get this information before surgical resection of the tumor, we evaluated 29 breast carcinoma patients with Tc-99m MIBI scintimammography and power Doppler ultrasound (US) with a microbubble contrast agent preoperatively and compare their results with intratumoral microvessel density (IMD) and reverse transcriptase-polymerase chain reaction (RT-PCR) of VEGF mRNA. IMD was well correlated with VEGF121 (r = 0.220, P = 0.024) and VEGF165 (r = 0.419, P = 0.046) mRNA level of the tumor. Power Doppler US grading of the tumor is well correlated with IMD (r = 0.552, P = 0.033). However, early uptake and washout index calculated from Tc-99m MIBI scintimammography showed no correlation with IMD or VEGF mRNA level, while washout index was inversely correlated with power Doppler US grading (r = -0.945, P = 0.001). In conclusion, the preoperative evaluation of breast cancer with power Doppler US with a microbubble contrast agent could predict tumor angiogenesis. Tc-99m MIBI scintimammography needs further study to use it as an image analysis for angiogenesis.

Differentiation of breast masses using 3-D sonographic and echo-enhancer-based evaluation of the vascular pattern: initial experiences

To evaluate the potential of combined 3-D B-mode and color Doppler (CD) data sets in the differentiation of breast masses, in 50 patients with histologically proven solid breast lesions, 3-D datasets were acquired. A 3-D display was created and volume calculation of tumors, their periphery and vasculature was performed. Time-intensity curves of enhancement after administration of a contrast agent were analyzed. Volumetry of tumor vasculature yielded no significant differences between malignant and benign tumors regarding vascularization of the center (2.60 vs. 2.88%) and periphery (6.66 vs. 3.78%). Only the mean values for the rise time in the center of the tumor, fibroadenoma (FA): 5.7 s and ductal invasive carcinoma (DIC): 15.8s; p = 0.05, and the time to peak in the periphery, FA: 21.0 s and DIC: 31.6 s; p = 0.03, differed significantly. The 3-D ultrasound (US) technique was of no additional value in differentiating breast masses. The calculation of time-intensity curves after administration of a contrast agent may be helpful in differentiating FA and DIC.

Differential effects of angiostatin, endostatin and interferon-alpha(1) gene transfer on in vivo growth of human breast cancer cells

The administration of different angiogenesis inhibitors by gene transfer has been shown to result in inhibition of tumor growth in animal tumor models, but the potency of these genes has been only partially evaluated in comparative studies to date. To identify the most effective anti-angiogenic molecule for delivery by retroviral vectors, we investigated the effects of angiostatin, endostatin and interferon(IFN)-alpha(1) gene transfer in in vivo models of breast cancer induced neovascularization and tumor growth. Moloney leukemia virus-based retroviral vectors for expression of murine angiostatin, endostatin and IFN-alpha(1) were generated, characterized, and used to transduce human breast cancer cell lines (MCF7 and MDA-MB435). Secretion of the recombinant proteins was confirmed by biological and Western blotting assays. Their production did not impair in vitro growth of these breast cancer cells nor their viability, and did not interfere with the expression of angiogenic factors. However, primary endothelial cell proliferation and migration in vitro were inhibited by supernatants of the transduced cells containing angiostatin, endostatin, and IFN-alpha(1). Stable gene transfer of the IFN-alpha(1) cDNA by retroviral vectors in both MCF7 and MDA-MB435 cells resulted in a marked and long-lasting inhibition of tumor growth in nude mice that was associated with reduced vascularization. Endostatin reduced the in vivo growth of MDA-MB435, but not MCF7 cells, despite similar levels of in vivo production, and angiostatin did not impair the in vivo growth of either cell line. These findings indicate heterogeneity in the therapeutic efficacy of angiostatic molecules delivered by viral vectors and suggest that gene therapy with IFN-alpha(1) and endostatin might be useful for treatment of breast cancer.

Tumor cell specific expression of MMP-2 correlates with tumor vascularisation in breast cancer

The metastatic potential of tumors is dependent on the ability of tumor cells to degrade extracellular matrix components by the expression of matrix metalloproteinases (MMPs) and to induce vascularisation of the tumor tissue. Thus, expression of MMPs and the number of blood vessel in tumor tissue may serve as prognostic markers of aggressive and metastasizing tumor growth. We have determined the vascularisation and the expression of MMP-2 by immuno-histochemical staining of 19 benign and 75 malignant breast tissue specimens with CD31- and MMP-2 specific antisera. The degree of vascularisation was expressed by intratumoral microvascular density (IMD), which takes into account all vessels present in a hot spot irrespective of their size. In addition, we have introduced a novel parameter, vascular grading (VG), which describes the percentage of small microvessels of <20 microm in diameter in the total number of blood vessels. IMD tended to indicate an elevated risk for metastasis formation and disease recurrence, while VG did not correlate with metastasis formation. Similarly, MMP-2 expression neither correlated with the clinical outcome of the disease nor with the classical histo-pathological parameters such as stage, grade, lymph node involvement and estrogen receptor status. Tumor cell-specific MMP-2 expression, however, showed a highly significant correlation with VG but not with IMD. These results indicate that MMP-2 expression is rather involved in the formation of small capillaries than in vessel maturation and tumor cell invasion. Thus, MMP-2 expression by tumor cells may serve as indicator of strong angiogenic induction potential of breast tumor cells.

Vasculogenic mimicry and pseudo-comedo formation in breast cancer

Tumors require a blood supply for growth and hematogenous metastases. Until recently, most research in this area has focused on the role of angiogenesis, the recruitment of new vessels into a tumor from preexisting vessels. Previously, in a study of breast cancer (IBC), in which we used established inflammatory breast cancer (IBC) xenografts (WIBC-9) originating from a patient with IBC (Shirakawa et al., Cancer Res 2001:61:445-451), we reported observing vasculogenic mimicry (VM), a condition in which bloodstreams within cancer tissue are not accompanied by a lining of endothelial cells (ECs) (Shirakawa et al., Cancer Res 2002:62:560-566). In the present study, we examined 331 surgically resected breast cancer specimens for evidence of VM, using immunohistochemistry and laser-captured microdissection (LCM) followed by nested reverse transcriptase polymerase chain reaction (RT-PCR). Surprisingly, 7.9% (26 specimens) of the 331 specimens exhibited evidence of VM. Of these 26 VM specimens, 84.6% (22 specimens) exhibited pseudo-comedo formation. RT-PCR analysis of 8 microdissected typical VM specimens revealed expression of Tie-2, Flt-1, thrombin receptor and CD31 in 63, 50, 0 and 0% of specimens, respectively. In contrast, results of RT-PCR analysis of 8 specimens from non-VM tumors were negative for expression of these genes. The 26 VM cases tended to have a higher percentage of hematogenous recurrence (p = 0.059) and a lower percentage of 5-year survival (p = 0.071) than the 305 non-VM cases. However, there were no significant differences in tumor size, lymph node metastasis, estrogen receptors or progesterone receptors between the 2 groups (p > 0.1). Our results suggest that the existence of VM increases the likelihood of hematogenous metastases and is in inverse proportion to prognosis.

Induction of endothelial cell apoptosis by the antivascular agent 5,6-Dimethylxanthenone-4-acetic acid

5,6-Dimethylxanthenone-4-acetic acid, synthesised in this laboratory, reduces tumour blood flow, both in mice and in patients on Phase I trial. We used TUNEL (TdT-mediated dUTP nick end labelling) assays to investigate whether apoptosis induction was involved in its antivascular effect. 5,6-Dimethylxanthenone-4-acetic acid induced dose-dependent apoptosis in vitro in HECPP murine endothelial cells in the absence of up-regulation of mRNA for tumour necrosis factor. Selective apoptosis of endothelial cells was detected in vivo in sections of Colon 38 tumours in mice within 30 min of administration of 5,6-Dimethylxanthenone-4-acetic acid (25 mg x kg(-1)). TUNEL staining intensified with time and after 3 h, necrosis of adjacent tumour tissue was observed. Apoptosis of central vessels in splenic white pulp was also detected in tumour-bearing mice but not in mice without tumours. Apoptosis was not observed in liver tissue. No apoptosis was observed with the inactive analogue 8-methylxanthenone-4-acetic acid. Positive TUNEL staining of tumour vascular endothelium was evident in one patient in a Phase I clinical trial, from a breast tumour biopsy taken 3 and 24 h after infusion of 5,6-Dimethylxanthenone-4-acetic acid (3.1 mg x m(-2)). Tumour necrosis and the production of tumour tumour necrosis factor were not observed. No apoptotic staining was seen in tumour biopsies taken from two other patients (doses of 3.7 and 4.9 mg x m(-2)). We conclude that 5,6-Dimethylxanthenone-4-acetic acid can induce vascular endothelial cell apoptosis in some murine and human tumours. The action is rapid and appears to be independent of tumour necrosis factor induction.

Tumour microvessel density as predictor of chemotherapy response in breast cancer patients

The aim of this study was to evaluate the predictive value of intratumoural microvessel density in breast cancer. We studied immunohistochemically primary tumours of 104 patients with metastasised breast cancer who took part in a randomised multicentre trial comparing docetaxel to sequential methotrexate and 5-fluorouracil. Vessels were highlighted with factor VIII staining and counted microscopically. Microvessel density was compared with clinical response to chemotherapy and patient survival. The microvessel density of the primary tumour was not significantly associated with patient's response to chemotherapy, time to progression or overall survival in the whole patient population or in the docetaxel or methotrexate and 5-fluorouracil groups. However, disease-free survival was longer in patients with low microvessel density (P=0.01). These findings suggest that microvessel density of the primary tumour cannot be used as a predictive marker for chemotherapy response in advanced breast cancer.

Association between nitrotyrosine levels and microvascular density in human breast cancer

Nitrotyrosine (NO2Y) is a global marker of protein modification by reactive nitrogen species such as peroxynitrite derived from nitric oxide (NO). Because NO and its derivatives are postulated to enhance carcinogenesis, we used stable isotope dilution mass spectrometry to measure the levels of NO2Y in 30 samples of human breast cancer of varying pathologic types. In the samples tested, the NO2Y levels were generally low (average of 14.1 +/- 9.2 micromol NO2Y per mole of tyrosine). Breast cancers with a high microvascular density, however, had a significantly higher average level of NO2Y than tumors with a low microvascular density (20 v.s. 10 micromol NO2Y per mole of tyrosine, p = 0.007 by two-tailed t-test, assuming unequal variances of two samples). There was no apparent association between NO2Y levels and the differentiation of the tumors, tumor aneuploidy, estrogen receptor status, HER-2 expression, lymph node status, or infiltration of the tumors by neutrophils or eosinophils. When the tissues were stained by immunohistochemistry for NO2Y, the NO2Y was localized predominantly within inflammatory cells located immediately adjacent to blood vessels at the edges of the tumors. NO2Y was generally not evident within the tumor cells or inflammatory cells in the stroma. We conclude that low levels of reactive nitrogen species are located predominantly within inflammatory cells near blood vessels of breast cancer and that higher NO2Y levels are associated with an increased density of blood vessels. Our findings, therefore, support a possible association between inflammatory cells and reactive nitrogen species in modulating microvascular density at the edges of breast cancer.

Correlation between vascular endothelial growth factor, angiogenesis, and tumor-associated macrophages in invasive ductal breast carcinoma

Angiogenic and anti-angiogenic factors, secreted by tumor, inflammatory, and stromal cells play an important role in regulation of neovascularization. Among the most important of these is vascular endothelial growth factor (VEGF), a specific mitogen for endothelium, which increases vascular permeability and induces proteolytic enzymes necessary for vascular remodeling. Tumor-associated macrophages (TAMs) can express complex functions related to tumor biology, including growth, proliferative rate, stroma formation and dissolution, and neovascularization. The aim of this study was to define, using immunohistochemical analysis, the microvessel density (MVD), VEGF expression, and TAMs level in 97 human invasive ductal breast carcinomas not otherwise specified (NOS), investigate a possible relationship between them and then correlate their values with tumor grade, mitotic activity index (MAI), tumor size and lymph-node status. Statistical analysis showed a strong positive relationship between MVD and VEGF expression ( P<0.001). Furthermore, both MVD and VEGF expression were significantly correlated with tumor grade and lymph-node status, and TAMs infiltration with MAI. TAM level showed a significant positive connection with VEGF expression and MVD. These in situ observations suggest that VEGF stimulates angiogenesis in human invasive ductal breast carcinoma NOS and attracts macrophages to the tumor locus, which then may be involved in angiogenesis promotion. The expression of this angiogenic molecule, and MVD and TAM level, can provide additional prognostic significance and help in the identification of patients who need postoperative adjuvant therapy.

Changes in microvessel density as assessed by CD34 antibodies after primary chemotherapy in human breast cancer

BACKGROUND

Several papers have shown that quantitationof tumor angiogenesis in primary breast cancer by counting blood vessels gives an independent assessment of prognosis. The impact of chemotherapy +/- endocrine therapy on the extent of angiogenesis is unknown.

METHODS

Matched pair histological tumor samples were obtained before and after primary chemotherapy from 120 breast cancer patients recruited in the same institution. The first 55 cases received cyclophosphamide, methotrexate, and 5-fluorouracil +/- Tamoxifen, whereas the subsequent 65 were submitted to single agent epirubicin. Patients underwent an incisional biopsy at diagnosis and definitive surgery on completion of three or four chemotherapy cycles. Microvessel density (MVD) was performed after staining with the CD34 monoclonal antibody.

RESULTS

MVD slightly decreased after chemotherapy [median 51.26 mm(2) (range 2.33-163.1) and 44.27 mm(2) (2.33-121.16; P < 0.001)]; this small reduction neither correlated with tumor response nor with changes in Ki67 expression. MVD at baseline significantly correlated with MVD assessed at definitive surgery (Spearman r = 0.70, P < 0.001). In multivariate analysis, c-erbB2 status showed an independent role in predicting the reduction in MVD that just failed to attain the statistical significance (P = 0.08), whereas baseline parameters, such as T, N, steroid hormone receptor, bcl-2, p53, c-erbB2, and Ki67 expression, did not enter the model.

CONCLUSIONS

Primary chemotherapy is able to modestly reduce the MVD in breast tumors. This small change is not biologically important, because the baseline neoangiogenesis status is not substantially changed. The change in microvessel count after chemotherapy could be potentially influenced by the c-erbB2 status.

Vascular endothelial growth factor in breast cancer: biologic and therapeutic aspects

Angiogenesis, or new blood vessel formation, is known to be an important part of the malignant phenotype in most cancers, including breast cancer. Recent years have seen the discovery of many regulators of the angiogenic process. Foremost among these is vascular endothelial growth factor (VEGF), the ligand for a family of specific transmembrane receptors that regulate the angiogenic process. This article describes the role of VEGF and its receptors in angiogenesis (both physiologic and pathologic), and describes efforts to target VEGF and its receptor. It discusses the outcome of some early trials involving VEGF-targeting agents, and reviews future therapeutic trials involving VEGF in breast cancer.

Cyclo-oxygenase 2 expression is associated with angiogenesis and lymph node metastasis in human breast cancer

AIMS

Cyclo-oxygenases 1 and 2 (COX-1 and COX-2) are key enzymes in prostaglandin biosynthesis. COX-2 is induced by a wide variety of stimuli, and present during inflammation. COX-2 overexpression has been observed in colon, head and neck, lung, prostate, stomach, and breast cancer. In colon and gastric cancer, COX-2 expression was associated with angiogenesis. The aim of this study was to determine the relation between COX-2 expression and angiogenesis in breast cancer, and to correlate the expression of this enzyme with classic clinicopathological parameters.

METHODS

COX-2 expression was investigated by immunohistochemistry and western blotting analysis. The expression of COX-2 was then related to age, histological grade, nodal status, oestrogen receptor status, p53 expression,c-erb-B2 overexpression, mitotic counts, MIB-1 labelling index, apoptotic index, sialyl-Tn expression, transforming growth factor alpha expression, microvessel density, and disease free survival in 46 patients with invasive ductal breast carcinoma.

RESULTS

By means of immunohistochemistry, COX-2 expression was detected in eight of the 46 carcinomas studied. Western blotting showed COX-2 protein expression in the same breast tumours, but not in normal adjacent tissues. The density of microvessels immunostained with anti-F-VIII related antigen was significantly higher in patients with COX-2 expression than in those without expression (p = 0.03). In addition, COX-2 was significantly associated with the presence of sialyl-Tn expression (p = 0.02), lymph node metastasis (p = 0.03), a high apoptotic index (p = 0.03), and a short disease free survival (p = 0.03) in univariate analyses.

CONCLUSIONS

These data suggest that COX-2 expression is associated with angiogenesis, lymph node metastasis, and apoptosis in human breast cancer. Moreover, these results warrant further studies with larger series of patients to confirm the association with short disease free survival in patients with breast cancer.

Role of vascular endothelial growth factor during breast cancer

We review the results of experimental and clinical observations on neoangiogenesis in patients with breast cancer. Vascular endothelial growth factor is an important positive regulator of this process. Experiments showed the possibility of using various direct and indirect antiangiogenic means in the therapy of breast cancer, but clinical efficiency of these methods was not proved. Expression of vascular endothelial growth factor can serve as a prognostic criterion in breast cancer. Antiangiogenic preparations should not be used as monotherapy, but as the treatment complementary to standard therapy.