Correlation between color power Doppler sonographic measurement of breast tumor vasculature and immunohistochemical analysis of microvessel density for the quantitation of angiogenesis

OBJECTIVE

To record the correlation between color power Doppler sonographic measurement of breast tumor vasculature and immunohistochemical analysis of microvessel density for the quantitation of angiogenesis.

METHODS

Women with palpable breast masses scheduled for excision biopsy were scanned with two- and three-dimensional color power Doppler sonography before and after the administration of a sonographic contrast agent. Vessel counts were performed on two- and three-dimensional sonographic images before and after contrast agent administration. All tumors were surgically removed and underwent immunohistochemical analysis for microvessel density assessment. The sonographic measure of tumor vascularity was correlated with microvessel density.

RESULTS

Pathologic examination showed 43 breast cancers and 14 benign breast masses. Higher microvessel density was noted in malignant than benign breast masses (P < .0005). Color power Doppler sonographic measurement of tumor vessel number showed a significant positive correlation with tumor size (P < .05) and progesterone receptor negativity (P < .05). A significant positive correlation was observed between microvessel density and the number of intratumoral blood vessels assessed by both two- and three-dimensional color power Doppler sonography (P < .05). Regression models showed three-dimensional color power Doppler sonography to have a significantly higher correlation with microvessel density when compared with two-dimensional color power Doppler sonography at baseline (P < .005). The administration of a sonographic contrast agent did not improve correlation with microvessel density.

CONCLUSIONS

A significant correlation was shown between color power Doppler sonographic measurement of tumor vascularity and microvessel density by immunohistochemical analysis. Further improvement in Doppler sonographic techniques to map capillary vessel flow should be explored to improve the current association with pathologic findings.

Immunohistochemical profile of cystosarcoma phyllodes of the breast: a study of 23 cases

Cystosarcoma phyllodes (CP) of the breast is a rare biphasic tumor composed of benign epithelium and a spindle cell stroma. Biologic behavior of CP cannot be predicted with certainty on the basis of morphologic criteria only. We studied immunohistochemical expression of basic fibroblastic growth factor (bFGF), urokinase, Ki67, p53 protein, and microvessel density in stromal and epithelial components of 14 low-grade CP (LCP) and 9 high-grade CP (HCP). bFGF was more often positive in LCP than in HCP. The stroma was positive for bFGF in 86% of LCP and 67% of HCP, and the epithelium was positive in 64% of LCP and 14% of HCP. Urokinase was positive in stromal cells of 86% of LCP and 93% of HCP. The epithelial positivity for urokinase in both groups resembled closely that of the stroma. p53 protein was more often positive in stromal cells of HCP (67%) than in LCP (50%). Ki67 was positive in the stroma of 43% of LCP and 89% of HCP and in the epithelium of 14% of LCP and 33% of HCP. There was no significant difference in microvessel density (MVD) in low- and high-grade lesions. Our study demonstrates that stromal Ki67 and p53 immunohistochemical positivity are more often associated with high-grade tumors. The positive immunostaining for bFGF, urokinase, Ki67, and p53 in stroma and epithelium of the majority of CP supports the existence of epithelial-stromal interactions and recognizes epithelium as an integral part of this tumor.

Quantitative real-time reverse transcription polymerase chain reaction: normalization to rRNA or single housekeeping genes is inappropriate for human tissue biopsies

Careful normalization is essential when using quantitative reverse transcription polymerase chain reaction assays to compare mRNA levels between biopsies from different individuals or cells undergoing different treatment. Generally this involves the use of internal controls, such as mRNA specified by a housekeeping gene, ribosomal RNA (rRNA), or accurately quantitated total RNA. The aim of this study was to compare these methods and determine which one can provide the most accurate and biologically relevant quantitative results. Our results show significant variation in the expression levels of 10 commonly used housekeeping genes and 18S rRNA, both between individuals and between biopsies taken from the same patient. Furthermore, in 23 breast cancers samples mRNA and protein levels of a regulated gene, vascular endothelial growth factor (VEGF), correlated only when normalized to total RNA, as did microvessel density. Finally, mRNA levels of VEGF and the most popular housekeeping gene, glyceraldehyde-3-phosphate dehydrogenase (GAPDH), were significantly correlated in the colon. Our results suggest that the use of internal standards comprising single housekeeping genes or rRNA is inappropriate for studies involving tissue biopsies.

Green tea and its catechins inhibit breast cancer xenografts

Investigators have shown that green tea may decrease the risk of cancer. It is widely accepted that the main active component of green tea is epigallocatechin-3-gallate (EGCG). In this study, we examined the effect of green tea on breast cancer growth and endothelial cells in in vitro assays and in animal models. Furthermore, we compared the potency of the different catechin components of green tea extract (GTE), including EGCG. Our data showed that mixed GTE and its individual catechin components were effective in inhibiting breast cancer and endothelial cell proliferation. In mouse experiments, GTE suppressed xenograft size and decreased the tumor vessel density. Our results demonstrated the value of all catechins and argued for the use of a mixed GTE as a botanical dietary supplement, rather than purified EGCG, in future clinical trials.

Expression and regulation of tumor suppressor gene maspin in breast cancer

Maspin (mammary serpin) is an inhibitor of serine proteases with tumor suppressor activity in breast cancer. Maspin was originally identified by subtractive hybridization in normal breast epithelial cells, but its expression decreased during tumor progression. The loss of maspin gene expression with increasing malignancy is by transcriptional regulation. Maspin is known to be involved in invasion and metastasis, interact with the p53 tumor suppressor pathway, and act as an inhibitor of angiogenesis. The immunohistochemical analysis and reverse-transcription polymerase chain reaction of maspin in normal human breast tissue and breast carcinoma indicated a stepwise reduction of maspin expression during the progression from ductal carcinoma in situ to invasive carcinoma to lymph node metastasis. The lack of maspin expression in breast cancer seems to be associated with a short disease-free survival and supports maspin's function as an indicator for tumor aggressiveness and metastatic potential. New studies on the gene regulation of maspin provide evidence for promising potential of possible re-expression of maspin in tumor cells. The function of maspin as a tumor suppressor gene involved in tumor invasion, metastasis, and angiogenesis may not be limited to breast cancer.

Experience of intravenous digital subtraction angiography (IV-DSA) in evaluation of neoadjuvant chemotherapy for advanced breast cancer

Intravenous digital subtraction angiography (IV-DSA) was performed before and after neoadjuvant chemotherapy (NACT) in five patients with locally advanced breast cancer, and the efficacy of NACT was evaluated on the basis of the results of IV-DSA and histopathological examination. Following NACT, the maximum density of tumor enhancement (MAX) in the IV-DSA image decreased by 61.6% in case 1, 50% in case 2, 58.1% in case 3, 90.8% in case 4, and 97.2% in case 5. In all five patients, the efficacy of chemotherapy was rated as a partial response in terms of tumor size, while histological efficacy was rated as slightly effective in cases 1-4 and moderately effective in case 5. The pathological efficacy of NACT was highest in case 5, which showed the greatest decrease in MAX. These results indicate that variations in MAX reflect clinical efficacy, and, to some extent, also permit prediction of pathological efficacy.

Development of contrast digital mammography

Development of breast tumors is often accompanied by angiogenesis--the formation of new blood vessels. It is possible to image the effects of this process by tracking the uptake and washout of contrast agents in the vicinity of a lesion. In this article, a method for carrying out contrast subtraction mammography on a full-field digital mammography unit is described. Spectral measurements and modeling were performed to optimize the choice of x-ray target, kilovoltage and x-ray beam filtration for contrast digital mammography (CDM) on an available digital mammography system. Phantom studies were carried out to determine the sensitivity of CDM to iodine. Detection of iodine area densities of 0.3 mg/cm2 is possible for a circular object with a radius of 1.3 mm, which allows detection of uptake levels in the breast typically seen with cancer and some benign breast conditions. It was found that with a molybdenum anode x-ray tube, copper filtration could be used to effectively shape the x-ray spectrum to maximize the proportion of x rays with energies above the k edge of iodine. Simple logarithmic subtraction was found to be adequate in suppressing background signals dependent on the x-ray beam intensity and background thickness of the breast. The total x-ray dose from the procedure ranges between 1 and 3 mGy, similar to that from a conventional single view film mammogram. A clinical pilot study is currently being carried out to evaluate this technique.

[Tc-99m]-sestamibi uptake and washout in locally advanced breast cancer are correlated with tumor blood flow

OBJECTIVES

To determine the influence of breast tumor blood flow on MIBI kinetics, we compared MIBI uptake and washout to [O-15]-water PET estimates of blood flow in patients with locally advanced breast cancer.

METHODS

Prior to therapy, 37 patients underwent MIBI and [O-15]-water PET imaging; 22/37 also had MIBI washout analysis. Twenty-five patients underwent serial imaging over the course of chemotherapy.

RESULTS

MIBI uptake and blood flow had a significant positive correlation pre-therapy. The change in MIBI uptake over the course of therapy also correlated with the change in blood flow. The half-time of MIBI washout inversely correlated with blood flow, indicating faster MIBI washout with higher blood flow.

CONCLUSIONS

Blood flow strongly influences early MIBI uptake and can be a factor affecting the rate of MIBI washout in breast tumors. We present a model of MIBI kinetics in tumors which forms a hypothesis for further mechanistic studies of MIBI uptake and washout in breast cancer.

Molecular targets as therapeutic strategies in the management of breast cancer

Therapy directed against specific biologic targets has long been used in the treatment of breast cancer; the estrogen receptor is a validated prognostic and therapeutic target, and antiestrogen therapy has been used effectively for decades. Recently, scientific progress and increased comprehension of mechanisms of breast cancer pathogenesis have led to the proliferation of both potential molecular targets and new therapeutic agents. The success of traztuzumab (Herceptin, Genentech, South San Francisco, CA), an anti-HER2 antibody, has spurred the development of other biologically directed therapeutics. In this overview, I discuss three targets relevant to breast cancer (the epidermal growth factor receptor family, angiogenesis, and NF-kappa B), and therapeutic approaches directed against these targets are discussed.

Issues and challenges for antiangiogenic therapies

Angiogenesis is defined as the growth and proliferation of blood vessels from the existing vasculature, allowing a developing tissue to obtain the nutrients necessary to maintain growth. This fundamental mechanism underlies the processes of reproduction, development and repair and occurs in both normal and tumor tissues. Since this process is confined to rapidly growing tissues, and is quiescent in normal tissues, it was hypothesized by Folkman that any therapeutic intervention that inhibited angiogenesis would be relatively specific to tumors, sparing normal tissue. The mechanisms by which tumors induce angiogenesis are complex. Tumors rapidly outgrow the capacity of the vasculature in their host tissue to provide nutrition and oxygenation, and are inherently hypoxic. In response to hypoxia, they produce a number of potent protein-mediators that stimulate the growth of new blood vessels. These angiogenic factors are not specific to tumors - they are produced by all tissues in response to hypoxia. Many of the mechanisms have been elucidated at a molecular level, and a number of ligands, receptors and signal-transduction pathways defined. Many of these represent potential targets for the development of novel therapeutic agents. Several drug candidates that target angiogenic mechanisms are currently being evaluated in breast cancer. The ultimate goal of all such development is to improve disease outcome, and to augment currently available therapies. However, the evaluation of these drug candidates in clinical studies is complex and requires a fundamental re-appraisal of conventional clinical trial methodology and the application of advanced bioscientific technology to facilitate understanding of the complex pharmacology that they may produce.

Arginine-glycine-aspartic acid (RGD)-peptide binds to both tumor and tumor-endothelial cells in vivo

Targeting tumor cells or tumor vasculature by peptides is a promising strategy for delivering cytotoxic drugs for cancer therapy. The identification of efficient targeting peptides depends on the availability of informative methods for determining cellular binding specificities. Here, we have used fluorescence-activated cell-sorting (FACS) analysis in combination with an isopentane freezing method to show targeted binding of the Arg-Gly-Asp (RGD)-4C-peptide labeled with FITC, not only to endothelial cells but also to tumor cells in human breast cancer xenografts grown in nude mice. Nontumorous cells showed only background binding. This study suggests, that the RGD-4C-peptide can target tumor endothelial cells as well as tumor cells. Consequently, it should be possible to design a combination therapy approach against both targets.

Antagonistic effect of NK4 on HGF/SF induced changes in the transendothelial resistance (TER) and paracellular permeability of human vascular endothelial cells

Hepatocyte growth factor/scatter factor (HGF/SF) is a multi-function cytokine that has been shown to regulate the expression of cell adhesion molecules in human endothelial cells. It is also a key cytokine in the development and progression of cancer, particularly during metastasis. NK4 is a variant of HGF/SF that has already been shown to be antagonistic to HGF/SF. This study shows that HGF/SF decreased transendothelial resistance (TER) and increased paracellular permeability in human vascular endothelial cells can that such effects can be inhibited by addition of the NK4 variant. In addition, HGF/SF-stimulated invasion of endothelium by breast cancer cells was inhibited by the addition of NK4. Western blotting revealed that HGF/SF decreased the protein level, and increased tyrosine phosphorylation of ZO-1, but did not cause a change in level of occludin or claudin-1, both molecules involved in tight junction function. RT-PCR revealed that addition of HGF/SF caused no change in signal for claudin-5 or junctional adhesion molecule (JAM), but there was a decrease in the signal for claudin-1. NK4 was able to prevent the decrease in levels of ZO-1 protein by HGF/SF.

Copper deficiency induced by tetrathiomolybdate suppresses tumor growth and angiogenesis

Copper plays an essential role in promoting angiogenesis. Tumors that become angiogenic acquire the ability to enter a phase of rapid growth and exhibit increased metastatic potential, the major cause of morbidity in cancer patients. We report that copper deficiency induced by tetrathiomolybdate (TM) significantly impairs tumor growth and angiogenesis in two animal models of breast cancer: an inflammatory breast cancer xenograft in nude mice and Her2/neu cancer-prone transgenic mice. In vitro, TM decreases the production of five proangiogenic mediators: (a) vascular endothelial growth factor; (b) fibroblast growth factor 2/basic fibroblast growth factor; (c) interleukin (IL)-1alpha; (d) IL-6; and (e) IL-8. In addition, TM inhibits vessel network formation and suppresses nuclear factor (NF)kappaB levels and transcriptional activity. Our study suggests that a major mechanism of the antiangiogenic effect of copper deficiency induced by TM is suppression of NFkappaB, contributing to a global inhibition of NFkappaB-mediated transcription of proangiogenic factors.

Dynamics of contrast enhancement in MR imaging and power Doppler ultrasonography of solid breast lesions

PURPOSE

To evaluate the dynamics of contrast enhancement in solid breast lesions at contrast-enhanced MR imaging and power Doppler ultrasonography (US) and to compare the methods to histology and to each other.

MATERIAL AND METHODS

Forty breast lesions were prospectively examined with dynamic MR and power Doppler US. Time-signal intensity curves of enhancement were obtained for both methods. The shape of the curve was analyzed to be benign, indeterminate or malignant. The curves were also analyzed quantitatively by calculating the slope of the curve and the area under the curve (both methods), relative enhancement (MR), and time to peak (US). The lesions were divided into malignant lesions, fibroadenomas, and other benign lesions. The results were compared to histology.

RESULTS

In the subjective analysis of the MR curve in differentiating between benign and malignant lesions the accuracy was 90%. The MR curve also enabled differentiation between fibroadenomas and malignancies. The accuracy of the US curve was 38%. Quantitatively, statistically significant differences were found using all the MR variables, except between malignancies and fibroadenomas. Using the US variables, no significant difference was found between the groups.

CONCLUSION

The dynamics of contrast-enhanced MR were reliable in the differential diagnosis of solid breast lesions, but contrast-enhanced power Doppler US was of limited value.

Parametric imaging of tumor perfusion using flow- and permeability-limited tracers

PURPOSE

To quantitatively evaluate the spatial distribution of flow- and permeability-limited perfusion in MCF7 human breast cancer tumors orthotopically implanted in CD1-NU mice.

MATERIALS AND METHODS

Flow-limited perfusion was derived from (2)H-MRI recorded before and after infusion of deuterated water. Permeability-limited perfusion was evaluated from GdDTPA-enhanced (1)H-MRI.

RESULTS

The dominant processes in tumor perfusion, namely blood flow and capillary permeability, were mapped in orthotopically implanted MCF7 human breast cancer tumors. The dynamic data were processed according to physiological models, yielding parametric maps of intravascular volume fraction, water perfusion rate, GdDTPA permeability rate constant, and extracellular volume fraction accessible to GdDTPA. The maps exhibited the heterogeneous distribution of each perfusion parameter. Most of the tumor tissue (> or =95%) was perfused with HDO, while GdDTPA was perfused in only about 50% of it. In most loci the perfusion rate was limited by capillary permeability to GdDTPA.

CONCLUSION

The results demonstrated the instructive value of tracers with different properties used in conjunction to achieve a deeper understanding of tumor perfusion capacity. This study offers tools for the accurate, noninvasive evaluation of drug delivery efficacy.

Magnetic resonance of the breast: correlation between enhancement patterns and microvessel density in malignant tumors

The continuous growth of a solid tumor is contingent upon the induction and formation of new vascular structures (angiogenesis). Several studies have established a close correlation between the microvessel density (MVD) of a tumor and its growth capacity. Therefore, a non-invasive method to accurately assess tumor MVD in vivo would be clinically useful. We studied 20 consecutive patients (age range: from 39 to 78 yrs; average age: 58.9 yrs), with malignant breast neoplasms using dynamic MR examinations with a paramagnetic contrast agent and post-operative pathological evaluation. We found that the differences in dynamic MRI enhancement are a direct consequence of microvascular distribution within the neoplasm. This study did not yield a statistically significant correlation between high microcirculation neo-formation and high aggressiveness of the neoplasm, but did indicate that further studies with a larger study populations are necessary.

[Analysis of vascularity in breast tumors--comparison of high frequency ultrasound and contrast-enhanced color harmonic imaging]

PURPOSE

To compare the ability of standard power Doppler and color harmonic imaging for visualising breast tumor vascularity using ultrasound probes of various frequencies, and to evaluate the influence on diagnostic accuracy using ultrasound contrast agent.

MATERIALS AND METHODS

Twenty patients (x = 43.6 +/- 11.7 years) with suspected malignancy of the breast underwent power Doppler to evaluate vascularity and to offer a differential diagnosis of the lesion. Two criteria were used for differential diagnosis: The quantitative extent of vascularity ("percentage vessel area", PVA) and the qualitative assessment of vascular architecture. The following power Doppler modes were compared in every patient: Plain and enhanced (Levovist(R)) 9 MHz and 12 MHz standard power mode and enhanced 9 MHz color harmonic imaging-(CHI).

RESULTS

The PVA increased from a mean of 2.2 +/- 2.9 % (9 MHz standard plain) via 4.8 +/- 4.1 % (12 MHz standard plain), 9.7 +/- 15.3 % (9 MHz standard enhanced), 17.4 +/- 20.0 % (9 MHz CHI enhanced) up to 19.4 +/- 14.8 % (12 MHz standard enhanced). The perceptibility of the vascular structure was best using the enhanced 12 MHz standard power mode, immediately followed by the enhanced 9 MHz CHI mode. The improved detection of vascular signal did not translate into improved diagnostic accuracy. The highest diagnostic accuracy (95 %) was obtained using the enhanced 9 MHz CHI mode (criterion "PVA") and the enhanced 9 MHz standard power mode (criterion "vascular structure"), whereas the 12 MHz probes delivered insufficient diagnostic accuracy and very low specificity.

CONCLUSION

Best quantitative and qualitative visualisation of the tumor vascularity was achieved using the enhanced 12 MHz standard power mode. Nevertheless, the highest diagnostic accuracy was obtained using enhanced 9 MHz standard power Doppler and enhanced 9 MHz color harmonic imaging. The visualisation of tumor vascularity and, partially, the diagnostic accuracy are improved significantly by color harmonic imaging without changing the probe frequently.

Magnetic resonance imaging of breast cancer angiogenesis: a review

The development and growth of solid tumors rely on a process known as perfusion which allows for the delivery and clearance of nutrients through their vasculature. The classical approach of studying tumor vasculature by histologic staining of endothelial cells provides a measure of microvessel density in areas of high vascularization (so-called "hot spots"). More advanced high-resolution, parametric, contrast-enhanced MRI techniques enable quantitative assessment of the vascular distribution and function over the entire tumor. Hence, MRI overcomes the intratumoral variation of the histological method. Clinical testing of the MRI approach, that evaluates the permeability and surface area of the tumor vasculature, demonstrates improved accuracy of breast cancer diagnosis.

Inhibition of fibroblast growth factors by green tea

Investigators have shown that green tea may decrease the risk of cancer. It is widely accepted that the main active component of green tea is EGCG (epigallocatechin-3-gallate). In our previous study, we examined the effect of green tea on breast cancer growth and endothelial cells both in in vitro assays and in animal models. Our data show that both mixed green tea extract (GTE) as well as its individual catechin components are effective in inhibiting breast cancer and endothelial cell proliferation in vitro, and that GTE suppresses breast cancer xenograft size and decreases the tumor blood vessel density in vivo. In the present study, we further demonstrate that 40 microg/ml GTE or EGCG can decrease the levels of the angiogenic factor bFGF (basic fibroblast growth factor) levels in the cells. This phenomenon is observed in both human umbilical vein endothelial cells (HUVECs) and in human breast cancer cells MDA-MB231. This effect is dose dependent. Furthermore, GTE and EGCG decrease the transcript levels of bFGF and aFGF (acidic fibroblast growth factor) in HUVECs and MDA-MB231 cells. Our findings suggest that the inhibition of the angiogenic fibroblast growth factors could account for one of the mechanisms of green tea's actions. Since cancer is angiogenesis dependent, this may partially explain the antineoplastic effects associated with green tea consumption.

Maximum intensity projection analysis in magnetic resonance of the breast

The aim of this study was to determine the sensitivity, specificity and accuracy of vascular asymmetries and vessel location seen using MR Maximum Intensity Projection imaging for malignant and benign lesions. We enrolled 101 women, with an age ranging from 29 to 69 years (mean age of 53.1 years), with a mammary nodule and candidate for surgical intervention. MR was carried out using a 1.5 Tesla superconductive magnet, equipped with a double and bilateral Phased Array dedicated coil. All images obtained were processed using MIP. The relationship between an asymmetry due to a greater amount of vascular structures in the breast with a malignant neoplasm and symmetry with benign neoplasms were statistically significant (p < 0.001): sensitivity of 71.8%, specificity 100% and accuracy 76.2%. The relationship between perilesional or intralesional vessels with malignant versus benign neoplasms were statistically significant (p < 0.001): sensitivity 88.5%, specificity 82.6% and accuracy 87.1%. We concluded that asymmetries between breasts and the presence of perilesional or intralesional vessels seen in MIP images are important signs and, therefore, must be reported.

[Application of color Doppler in diagnosis of malignant breast tumors]

The object of our research was estimation of blood flow with the application of colour Doppler within the scope of changes that occurred in female patients suffering from malignant breast tumours. The research covered 30 female patients and the results pointed to great usefulness of this method in diagnostics of malignant breast tumour.

The redox protein thioredoxin-1 (Trx-1) increases hypoxia-inducible factor 1alpha protein expression: Trx-1 overexpression results in increased vascular endothelial growth factor production and enhanced tumor angiogenesis

Hypoxia-inducible factor 1 (HIF-1), a heterodimer of HIF-1alpha and HIF-1beta subunits, is a transcriptional activator central to the cellular response to low oxygen that includes metabolic adaptation, angiogenesis, metastasis, and inhibited apoptosis. Thioredoxin-1 (Trx-1) is a small redox protein overexpressed in a number of human primary tumors. We have examined the effects of Trx-1 on HIF activity and the activation of downstream genes. Stable transfection of human breast carcinoma MCF-7 cells with human Trx-1 caused a significant increase in HIF-1alpha protein levels under both normoxic (20% oxygen) and hypoxic (1% oxygen) conditions. Trx-1 increased hypoxia-induced HIF-1 transactivation activity measured using a luciferase reporter under the control of the hypoxia response element. Changes in HIF-1alpha mRNA levels did not account for the changes observed at the protein level, and HIF-1beta protein levels did not change. Trx-1 transfection also caused a significant increase in the protein products of hypoxia-responsive genes, including vascular endothelial growth factor (VEGF) and nitric oxide synthase 2 in a number of different cell lines (MCF-7 human breast and HT29 human colon carcinomas and WEHI7.2 mouse lymphoma cells) under both normoxic and hypoxic conditions. The pattern of expression of the different isoforms of VEGF was not changed by Trx-1. Transfection of a redox-inactive Trx-1 (C32S/C35S) markedly decreased levels of HIF-1alpha protein, HIF-1 transactivating activity, and VEGF protein in MCF-7 cells compared with empty vector controls. In vivo studies using WEHI7.2 cells transfected with Trx-1 showed significantly increased tumor VEGF and angiogenesis. The results suggest that Trx-1 increases HIF-1alpha protein levels in cancer cells and increases VEGF production and tumor angiogenesis.