Distinct angiogenic patterns are associated with high-grade in situ ductal carcinomas of the breast

Targeting the Tumor Microenvironment in Breast Cancer: Prognostic and Predictive Significance and Therapeutic Opportunities

Breast cancer is one of the most prevalent tumors among women. Its prognosis and treatment outcomes depend on factors related to tumor cell biology. However, recent studies have revealed the critical role of the tumor microenvironment (TME) in the development, progression, and treatment response of breast cancer. In this review, we explore the different components of the TME and their relevance as prognostic and predictive biomarkers in breast cancer. In addition, techniques for assessing the tumor microenvironment, such as immunohistochemistry or gene expression profiling, and their clinical utility in therapeutic decision-making are examined. Finally, therapeutic strategies targeting the TME are reviewed, highlighting their potential clinical benefits. Overall, this review emphasizes the importance of the TME in breast cancer and its potential as a clinical tool for better patient stratification and the design of personalized therapies.

Everybody needs good neighbours: the progressive DCIS microenvironment

Ductal carcinoma in situ (DCIS) is a pre-invasive form of breast cancer where neoplastic luminal cells are confined to the ductal tree. While as many as 70% of DCIS cases will remain indolent, most women are treated with surgery, often combined with endocrine and radiotherapies. Overtreatment is therefore a major issue, demanding new methods to stratify patients. Somewhat paradoxically, the neoplastic cells in DCIS are genetically comparable to those in invasive disease, suggesting the tumour microenvironment is the driving force for progression. Clinical and mechanistic studies highlight the complex DCIS microenvironment, with multiple cell types competing to regulate progression. Here, we examine recent studies detailing distinct aspects of the DCIS microenvironment and discuss how these may inform more effective care.

Quantification of dynamic contrast-enhanced ultrasound (CEUS) in non-cystic breast lesions using external perfusion software

The aim of this present clinical pilot study is the display of typical perfusion results in patients with solid, non-cystic breast lesions. The lesions were characterized using contrast enhanced ultrasound (CEUS) with (i) time intensity curve analyses (TIC) and (ii) parametric color maps. The 24 asymptomatic patients included were genetically tested for having an elevated risk for breast cancer. At a center of early detection of familial ovary and breast cancer, those patients received annual MRI and grey-scale ultrasound. If lesions remained unclear or appeared even suspicious, those patients also received CEUS. CEUS was performed after intravenous application of sulfur hexafluoride microbubbles. Digital DICOM cine loops were continuously stored for one minute in PACS (picture archiving and communication system). Perfusion images and TIC analyses were calculated off-line with external perfusion software (VueBox). The lesion diameter ranged between 7 and 15 mm (mean 11 ± 3 mm). Five hypoechoic irregular lesions were scars, 6 lesions were benign and 12 lesions were highly suspicious for breast cancer with irregular enhancement at the margins and a partial wash out. In those 12 cases, histopathology confirmed breast cancer. All the suspicious lesions were correctly identified visually. For the perfusion analysis only Peak Enhancement (PE) and Area Under the Curve (AUC) added more information for correctly identifying the lesions. Typical for benign lesions is a prolonged contrast agent enhancement with lower PE and prolonged wash out, while scars are characterized typically by a reduced enhancement in the center. No differences (p = 0.428) were found in PE in the center of benign lesions (64.2 ± 28.9 dB), malignant lesions (88.1 ± 93.6 dB) and a scar (40.0 ± 17.0 dB). No significant differences (p = 0.174) were found for PE values at the margin of benign lesions (96.4 ± 144.9 dB), malignant lesions (54.3 ± 86.2 dB) or scar tissue (203.8 ± 218.9 dB). Significant differences (p < 0.001) were found in PE of the surrounding tissue when comparing benign lesions (33.6 ± 25.2 dB) to malignant lesions (15.7 ± 36.3 dB) and scars (277.2 ± 199.9 dB). No differences (p = 0.821) were found in AUC in the center of benign lesions (391.3 ± 213.7), malignant lesions (314.7 ± 643.9) and a scar (213.1 ± 124.5). No differences (p = 0.601) were found in AUC values of the margin of benign lesions (313.3 ± 372.8), malignant lesions (272.6 ± 566.4) or scar tissue (695.0 ± 360.6). Significant differences (p < 0.01) were found in AUC of the surrounding tissue for benign lesions (151.7 ± 127.8), malignant lesions (177.9 ± 1345.6) and scars (1091 ± 693.3). There were no differences in perfusion evaluation for mean transit time (mTT), rise time (RT) and time to peak (TTP) when comparing the center to the margins and the surrounding tissue. The CEUS perfusion parameters PE and AUC allow a very good assessment of the risk of malignant breast lesions and thus a downgrading of BI-RADS 4 lesions. The use of the external perfusion software (VueBox, Bracco, Milan, Italy) did not lead to any further improvement in the diagnosis of suspicious breast lesions and does appears not to have any additional diagnostic value in breast lesions.

CCL8 mediates crosstalk between endothelial colony forming cells and triple-negative breast cancer cells through IL-8, aggravating invasion and tumorigenicity

Triple-negative breast cancer (TNBC) is an aggressive type of breast cancer with a poor prognosis for which no effective therapeutic measures are currently available. The present study aimed to investigate whether interactions with endothelial colony-forming cells (ECFCs) promote aggressive progression of TNBC cells. Herein, using an indirect co-culture system, we showed that co-culture increased the invasive and migratory phenotypes of both MDA-MB-231 TNBC cells and ECFCs. Through a cytokine antibody array and RT-PCR analysis, we revealed that co-culture markedly induced secretion of the chemokine C-C motif ligand (CCL)8 from ECFCs and that of interleukin (IL)-8 from MDA-MB-231 cells. CCL8 was crucial for ECFC-induced IL-8 secretion and invasion of MDA-MB-231 cells as well as for MDA-MB-231-enhanced MMP-2 secretion and angiogenesis of ECFCs. We suggest c-Jun as a transcription factor for CCL8-induced IL-8 expression in MDA-MB-231 cells. IL-8 was important for co-culture-induced CCL8 and MMP-2 upregulation and invasion of ECFCs. Notably, our findings reveal a positive feedback loop between CCL8 and IL-8, which contributes to the aggressive phenotypes of both ECFC and TNBC cells. Using an MDA-MB-231 cell-based xenograft model, we show that tumor growth and metastasis are increased by co-injected ECFCs in vivo. Increased expression of IL-8 was observed in tissues with bone metastases in mice injected with conditioned media from co-cultured cells. High IL-8 levels are correlated with poor recurrence-free survival in TNBC patients. Together, these results suggest that CCL8 and IL-8 mediate the crosstalk between ECFCs and TNBC, leading to aggravation of tumorigenicity in TNBC.

Can supplementary contrast-enhanced MRI of the breast avoid needle biopsies in suspicious microcalcifications seen on mammography? A systematic review and meta-analysis

Purpose

To analyze the rate of potentially avoidable needle biopsies in mammographically suspicious calcifications if supplementary Contrast-Enhanced MRI (CE-MRI) is negative.

Methods

Using predefined criteria, a systematic review was performed. Studies investigating the use of supplemental CE-MRI in the setting of mammographically suspicious calcifications undergoing stereotactic biopsy and published between 2000 and 2020 were eligible. Two reviewers extracted study characteristics and true positives (TP), false positives, true negatives and false negatives (FN). Specificity, in this setting equaling the number of avoidable biopsies and FN rates were calculated. The maximum pre-test probability at which post-test probabilities of a negative CE-MRI met with BI-RADS benchmarks was determined by a Fagan nomogram. Random-effects models, I²-statistics, Deek’s funnel plot testing and meta-regression were employed. P-values <0.05 were considered significant.

Results

Thirteen studies investigating 1414 lesions with a cancer prevalence of 43.6% (range: 22.7–66.9%) were included. No publication bias was found (P = 0.91). CE-MRI performed better in pure microcalcification studies compared to those also including associate findings (P < 0.001). In the first group, the pooled rate of avoidable biopsies was 80.6% (95%-CI: 64.6–90.5%) while the overall and invasive cancer FN rates were 3.7% (95%-CI: 1.2–6.2%) and 1.6% (95%-CI 0–3.6%), respectively. Up to a pre-test probability of 22%, the post-test probability did not exceed 2%.

Conclusion

A negative supplementary CE-MRI could potentially avoid 80.6% of unnecessary stereotactic biopsies in BI-RADS 4 microcalcifications at a cost of 3.7% missed breast cancers, 1.6% invasive. BI-RADS benchmarks for downgrading mammographic calcifications would be met up to a pretest probability of 22%.

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A negative breast MRI can downgrade up to 80.6% of suspicious microcalcifications, potentially avoiding vacuum-assisted breast biopsies.

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Up to a pretest probability of 22% , a negative breast MRI result would not exceed the 2% cancer rate required for a BI-RADS 3 category assignment.

Anti-Angiogenic Effects of Phytochemicals on miRNA Regulating Breast Cancer Progression

Several phytochemicals have been identified for their role in modifying miRNA regulating tumor progression. miRNAs modulate the expression of several oncogenes and tumor suppressor genes including the genes that regulate tumor angiogenesis. Hypoxia inducible factor-1 alpha (HIF-1α) signaling is a central axis that activates oncogenic signaling and acts as a metabolic switch in endothelial cell (EC) driven tumor angiogenesis. Tumor angiogenesis driven by metabolic reprogramming of EC is crucial for tumor progression and metastasis in many different cancers, including breast cancers, and has been linked to aberrant miRNA expression profiles. In the current article, we identify different miRNAs that regulate tumor angiogenesis in the context of oncogenic signaling and metabolic reprogramming in ECs and review how selected phytochemicals could modulate miRNA levels to induce an anti-angiogenic action in breast cancer. Studies involving genistein, epigallocatechin gallate (EGCG) and resveratrol demonstrate the regulation of miRNA-21, miRNA-221/222 and miRNA-27, which are prognostic markers in triple negative breast cancers (TNBCs). Modulating the metabolic pathway is a novel strategy for controlling tumor angiogenesis and tumor growth. Cardamonin, curcumin and resveratrol exhibit their anti-angiogenic property by targeting the miRNAs that regulate EC metabolism. Here we suggest that using phytochemicals to target miRNAs, which in turn suppresses tumor angiogenesis, should have the potential to inhibit tumor growth, progression, invasion and metastasis and may be developed into an effective therapeutic strategy for the treatment of many different cancers where tumor angiogenesis plays a significant role in tumor growth and progression.

Ductal carcinoma in situ of the breast: an update for the pathologist in the era of individualized risk assessment and tailored therapies

Ductal carcinoma in situ (DCIS) is a neoplastic proliferation of mammary ductal epithelial cells confined to the ductal-lobular system, and a non-obligate precursor of invasive disease. While there has been a significant increase in the diagnosis of DCIS in recent years due to uptake of mammography screening, there has been little change in the rate of invasive recurrence, indicating that a large proportion of patients diagnosed with DCIS will never develop invasive disease. The main issue for clinicians is how to reliably predict the prognosis of DCIS in order to individualize patient treatment, especially as treatment ranges from surveillance only, breast-conserving surgery only, to breast-conserving surgery plus radiotherapy and/or hormonal therapy, and mastectomy with or without radiotherapy. We conducted a semi-structured literature review to address the above issues relating to "pure" DCIS. Here we discuss the pathology of DCIS, risk factors for recurrence, biomarkers and molecular signatures, and disease management. Potential mechanisms of progression from DCIS to invasive cancer and problems faced by clinicians and pathologists in diagnosing and treating this disease are also discussed. Despite the tremendous research efforts to identify accurate risk stratification predictors of invasive recurrence and response to radiotherapy and endocrine therapy, to date there is no simple, well-validated marker or group of variables for risk estimation, particularly in the setting of adjuvant treatment after breast-conserving surgery. Thus, the standard of care to date remains breast-conserving surgery plus radiotherapy, with or without hormonal therapy. Emerging tools, such as pathologic or biologic markers, may soon change such practice. Our review also includes recent advances towards innovative treatment strategies, including targeted therapies, immune modulators, and vaccines.

Cellular and Molecular Changes in MNU-Induced Breast Tumours Injected with PF4 or bFGF

Background: Angiogenic activity has been considered to reflect important molecular events during breast tumour development. The present study concerned cellular and molecular changes of MNU-induced breast tumours subjected to promotion and suppression of angiogenesis. Methods: Female Sprague Dawley rats at the age of 21 days received MNU at the dose 70 mg/kg of body weight by intraperitoneal injection. Three months post-carcinogen initiation, mammary tumours were palpated and their growth was monitored. When the tumour diameter reached 1.0 ± 0.05 cm, rats were given bFGF or PF4 intratumourally at a dose of 10 μg/tumour. Entire palpable tumour were subsequently excised and subjected to histology examination, IHC staining, and RT-PCR. Results: No critical morphological changes were observed between pro-angiogenic factor, bFGF, and control groups. However, increase of tumour size with more necrotic and diffuse areas was notable in tumours after anti-angiogenic PF4 intervention. ER and PR mRNA expression was significantly up- and down-regulated in bFGF and PF4 groups, respectively. The trends were significantly associated with peri- and intratumoural MVD counts. However, irrespective of whether we promoted or inhibited angiogenesis, the expression of EGFR and ERBB2 continued to be significantly increased but this was not significantly associated with the MVD score. No significant differences in E-cadherin and LR gene expression were noted between intervention and control groups. Conclusion: ER and PR receptor expression shows consistent responses when tumour angiogenesis is manipulated either positively or negatively. Our study adds to current understanding that not only do we need to target hormonal receptors, as presently practiced, but we also need to target endothelial receptors to successfully treat breast cancer.

Is breast MRI a helpful additional diagnostic test in suspicious mammographic microcalcifications?

PURPOSE

Microcalcifications are a common finding in mammography and usually require invasive procedures to diagnose or exclude malignancy. As many microcalcifications are due to benign lesions, we wanted to assess whether breast MRI as an additional diagnostic tool may be used to distinguish benign from malignant in this setting.

MATERIALS AND METHODS

Eligible for this retrospective, IRB-approved observational study were 858 consecutive patients (mean age 54±11years) undergoing stereotactically-guided biopsies of suspicious mammographic microcalcifications during three year at our institution. Finally included were 152 patients who also underwent breast MRI <8weeks prior to biopsy. In case of malignant or lesions of uncertain malignant potential, subsequent surgery was performed. Benign findings were confirmed by imaging follow-up. BI-RADS category assignments from the original mammography and breast MRI reports were compared to the final diagnosis (benign vs. malignant) to determine diagnostic benchmarks.

RESULTS

Histopathology revealed 81 benign (53.3%), 41 DCIS (27%) and 30 (19.7%) invasive cancers. Sensitivity, specificity, positive and negative predictive values for breast MRI were 97.2% (69/71), 39.5% (32/81), 58.5% (69/118) and 94.1% (32/34), respectively. Thus, 32/81 unnecessary biopsies in benign lesions (39.5%) may have been avoided, missing 2/71 malignant lesions (2.8%), both DCIS G2.

CONCLUSION

Breast MRI as an additional diagnostic tool can be used to accurately distinguish benign from malignant mammographic microcalcifications and may thus be helpful to reduce unnecessary breast biopsies.

Ductal Carcinoma In Situ Biology, Biomarkers, and Diagnosis

Ductal carcinoma in situ (DCIS) is an often-diagnosed breast disease and a known, non-obligate, precursor to invasive breast carcinoma. In this review, we explore the clinical and pathological features of DCIS, fundamental elements of DCIS biology including gene expression and genetic events, the relationship of DCIS with recurrence and invasive breast cancer, and the interaction of DCIS with the microenvironment. We also survey how these various elements are being used to solve the clinical conundrum of how to optimally treat a disease that has potential to progress, and yet is also likely over-treated in a significant proportion of cases.

The effect of newly synthesized progesterone derivatives on apoptotic and angiogenic pathway in MCF-7 breast cancer cells

Due to its high potency and selectivity, anticancer agents consisting of combined molecules have gained great interests. The current study introduces newly synthesized progesterone derivatives of promising anticancer effect. Moreover, the pro-apoptotic and anti-angiogenic effects of these compounds were studied extensively. Several thiazole, pyridine, pyrazole, thiazolopyridine and pyrazolopyridine progesterone derivatives were synthesized. The structure of the novel progesterone derivatives was elucidated and confirmed using the analytical and spectral data. This novel derivatives were tested for their cytotoxic effect against human breast cancer cells (MCF-7) using neutral red uptake assay. Tested compounds showed anticancer activity against MCF-7 cancer cell line in the descending order of 7>2>3>8>6>9>4. The expression levels of Bcl-2, survivin, CCND1, CDC2, P53 and P21, VEGF, Hif-1α, MMP-2, MMP-9, Ang-1, Ang-2, and FGF-1 genes were investigated using QRT-PCR (Quantitative real time-polymerase chain reaction). The study clarified that compounds 2, 3, 4, 6, 7, 8 and 9 showed significant pro-apoptotic effect through the down regulation of Bcl-2., besides, survivin and CCND1 expression levels were down regulated by compounds 3, 4, 6, 7, 8, 9. However, Compound 4 may exert this pro-apoptotic effect through the up-regulation of P53 gene expression. On the other hand, the anti-angiogenic effect of these newly synthesized derivatives was due to their down regulation of VEGF, Ang-2, MMP-9 and FGF-1; and the up-regulation of HIF-1α and ang-1. This study recommended promising pro-apoptotic and anti-angiogenic anticancer agents acting through the regulation of key regulators of apoptosis, cell cycle genes, and pro-angiogenic genes.

Differentiation of ductal carcinoma in situ versus fibrocystic changes by magnetic resonance imaging: are there pathognomonic imaging features?

Background In breast magnetic resonance imaging (MRI), the diagnosis of ductal carcinoma in situ (DCIS) remains controversial; the most challenging cause of false-positive DCIS diagnosis is fibrocystic changes (FC). Purpose To search for typical and pathognomonic patterns of DCIS and FC using a standard clinical MRI protocol. Material and Methods Consecutive patients scheduled for breast MRI (standardized protocols @ 1.5T: dynamic-T1-GRE before/after Gd-DTPA [0.1 mmol/kg body weight (BW)]; T1-TSE), with subsequent pathological sampling, were investigated. Sixteen MRI descriptors were prospectively assessed by two experienced radiologists in consensus (blinded to pathology) and explored in patients with DCIS (n = 77) or FC (n = 219). Univariate and multivariate statistics were performed to identify the accuracy of descriptors (alone, combined). Furthermore, pathognomonic descriptor-combinations with an accuracy of 100% were explored (χ² statistics; decision trees). Results Six breast MRI descriptors significantly differentiated DCIS from FC ( P_corrected < 0.05; odds ratio < 7.9). Pathognomonic imaging features were present in 33.8% (n = 100) of all cases allowing the identification of 42.9% of FC (n = 94). Conclusion Pathognomonic patterns of DCIS and FC were frequently observed in a standard clinical MRI protocol. Such imaging patterns could decrease the false-positive rate of breast MRI and hence might help to decrease the number of unnecessary biopsies in this clinically challenging subgroup.

Tamoxifen Directly Inhibits Platelet Angiogenic Potential and Platelet-Mediated Metastasis

OBJECTIVE

Platelets, which are mainly known for their role in hemostasis, are now known to play a crucial role in metastasis. Tamoxifen is a selective estrogen receptor modulator that is widely used for the treatment of breast cancer. Tamoxifen and its metabolites have been shown to directly impact platelet function, suggesting that this drug has additional mechanisms of action. The purpose of this study was to determine whether tamoxifen exerts antitumor effects through direct platelet inhibition.

APPROACH AND RESULTS

This study found that pretreatment with tamoxifen leads to a significant inhibition of platelet activation. Platelets exposed to tamoxifen released significantly lower amounts of proangiogenic regulator vascular endothelial growth factor. In vitro angiogenesis assays confirmed that tamoxifen pretreatment led to diminished capillary tube formation and decreased endothelial migration. Tamoxifen and its metabolite, 4-hydroxytamoxifen, also significantly inhibited the ability of platelets to promote metastasis in vitro. Using a membrane-based array, we identified several proteins associated with angiogenesis metastasis that were lower in activated releasate from tamoxifen-treated platelets, including angiogenin, chemokine (C-X-C motif) ligand 1, chemokine (C-C motif) ligand 5, epidermal growth factor, chemokine (C-X-C motif) ligand 5, platelet-derived growth factor dimeric isoform BB, whereas antiangiogenic angiopoietin-1 was elevated. Platelets isolated from patients on tamoxifen maintenance therapy were also found to have decreased activation responses, diminished vascular endothelial growth factor release, and lower angiogenic and metastatic potential.

CONCLUSIONS

We demonstrate that tamoxifen and its metabolite 4-hydroxytamoxifen directly alter platelet function leading to decreased angiogenic and metastatic potential. Furthermore, this study supports the idea of utilizing targeted platelet therapies to inhibit the platelet's role in angiogenesis and malignancy.

Lattice-based model of ductal carcinoma in situ suggests rules for breast cancer progression to an invasive state

Ductal carcinoma in situ (DCIS) is a heterogeneous group of non-invasive lesions of the breast that result from abnormal proliferation of mammary epithelial cells. Pathologists characterize DCIS by four tissue morphologies (micropapillary, cribriform, solid, and comedo), but the underlying mechanisms that distinguish the development and progression of these morphologies are not well understood. Here we explored the conditions leading to the emergence of the different morphologies of DCIS using a two-dimensional multi-cell lattice-based model that incorporates cell proliferation, apoptosis, necrosis, adhesion, and contractility. We found that the relative rates of cell proliferation and apoptosis governed which of the four morphologies emerged. High proliferation and low apoptosis favored the emergence of solid and comedo morphologies. In contrast, low proliferation and high apoptosis led to the micropapillary morphology, whereas high proliferation and high apoptosis led to the cribriform morphology. The natural progression between morphologies cannot be investigated in vivo since lesions are usually surgically removed upon detection; however, our model suggests probable transitions between these morphologies during breast cancer progression. Importantly, cribriform and comedo appear to be the ultimate morphologies of DCIS. Motivated by previous experimental studies demonstrating that tumor cells behave differently depending on where they are located within the mammary duct in vivo or in engineered tissues, we examined the effects of tissue geometry on the progression of DCIS. In agreement with our previous experimental work, we found that cells are more likely to invade from the end of ducts and that this preferential invasion is regulated by cell adhesion and contractility. This model provides additional insight into tumor cell behavior and allows the exploration of phenotypic transitions not easily monitored in vivo.

Breast cancer is a complex disease that affects women worldwide. One heterogeneous group of lesions, ductal carcinoma in situ (DCIS), often begins as a nonmalignant disease but can readily progress if left untreated. The progression of this disease is not well understood because DCIS is typically removed upon detection. Therefore, computational models might help predict whether DCIS will remain nonmalignant or progress towards invasive ductal carcinoma. Here we used a multi-cell lattice-based model to explore the relative effects of cell proliferation, death, division axis, adhesion and contractility on the development and progression of DCIS. We also examined the emergence and progression of DCIS in physiologically relevant geometries of the mammary duct. Our model suggests several plausible progressions between morphologies of DCIS, and predicts that some regions of a duct are preferential for tumor cell invasion.

Loss of epigenetic Kruppel-like factor 4 histone deacetylase (KLF-4-HDAC)-mediated transcriptional suppression is crucial in increasing vascular endothelial growth factor (VEGF) expression in breast cancer

Vascular endothelial growth factor (VEGF) is recognized as an important angiogenic factor that promotes angiogenesis in a series of pathological conditions, including cancer, inflammation, and ischemic disorders. We have recently shown that the inflammatory transcription factor SAF-1 is, at least in part, responsible for the marked increase of VEGF levels in breast cancer. Here, we show that SAF-1-mediated induction of VEGF is repressed by KLF-4 transcription factor. KLF-4 is abundantly present in normal breast epithelial cells, but its level is considerably reduced in breast cancer cells and clinical cancer tissues. In the human VEGF promoter, SAF-1- and KLF-4-binding elements are overlapping, whereas SAF-1 induces and KLF-4 suppresses VEGF expression. Ectopic overexpression of KLF-4 and RNAi-mediated inhibition of endogenous KLF-4 supported the role of KLF-4 as a transcriptional repressor of VEGF and an inhibitor of angiogenesis in breast cancer cells. We show that KLF-4 recruits histone deacetylases (HDACs) -2 and -3 at the VEGF promoter. Chronological ChIP assays demonstrated the occupancy of KLF-4, HDAC2, and HDAC3 in the VEGF promoter in normal MCF-10A cells but not in MDA-MB-231 cancer cells. Co-transfection of KLF-4 and HDAC expression plasmids in breast cancer cells results in synergistic repression of VEGF expression and inhibition of angiogenic potential of these carcinoma cells. Together these results identify a new mechanism of VEGF up-regulation in cancer that involves concomitant loss of KLF-4-HDAC-mediated transcriptional repression and active recruitment of SAF-1-mediated transcriptional activation.

Ductal carcinoma in situ of the breast: current concepts and future directions

CONTEXT

In situ carcinomas of the breast constitute 15% to 30% of all newly diagnosed breast cancer cases; 80% of these in situ lesions belong to the ductal carcinoma in situ (DCIS) category. Similar to invasive breast carcinomas, DCIS is not a single disease but rather many distinct diseases with different histopathologic and molecular characteristics, a propensity to progress to invasive disease, and differential response to treatment.

OBJECTIVE

To review the classic pathologic parameters of clinical significance and the differential diagnosis of the DCIS lesions, present our new understanding of the importance of biomarkers, and discuss innovative approaches for targeted therapy in DCIS.

DATA SOURCES

Extensive review of the relevant peer-reviewed literature.

CONCLUSIONS

In DCIS, improved understanding of the underlying biologic pathways of tumor progression is expected to lead to more accurate classification and innovative targeted treatment approaches for the management of these lesions.

Biofunctional characteristics of in situ and invasive breast carcinoma

PURPOSE

The increasing use of breast-conserving surgery makes it essential to identify biofunctional profiles responsible for the progression of in situ to invasive carcinomas to facilitate the detection of lesions that are most likely to relapse or progress and, thus, to be able to offer patients tailored treatment options. Our objective was to analyse and compare biofunctional profiles in ductal carcinomas in situ (DCIS) and invasive ductal carcinomas (IDC). We also aimed to identify markers in tumor and normal surrounding tissues that may be predictive of locoregional recurrence in patients with DCIS.

METHODS

Biofunctional parameters including mitotic activity, estrogen receptor, progesterone receptor, microvessel density (MVD), c-kit and p27 expression were evaluated in 829 in situ and invasive carcinomas. The impact of the biomarker profiles of DCIS, IDC and normal surrounding tissues on loco-regional recurrence was analyzed.

RESULTS

A progressive increase in cell proliferation and a concomitant decrease in steroid hormone receptor-positive lesions was observed during the transition from in situ to invasive carcinomas, as also within each subgroup as grade increased. Conversely, p27 expression and MVD dramatically decreased during the transition from in situ to invasive carcinomas. Finally, we found that a low c-kit expression was indicative of IDC relapse.

CONCLUSIONS

Cell proliferation, hormonal and differentiation characteristics differed in DCIS with respect to IDC, and the main variation in the transition between the two histologic lesions was the decrease in p27 expression and MVD.

Dynamic contrast-enhanced MRI reveals the extent and the microvascular pattern of breast ductal carcinoma in situ

To report the role of magnetic resonance imaging (MRI) in assessing the extent of breast ductal carcinoma in situ (DCIS). To assess whether the microvascularity pattern in DCIS correlates with magnetic resonance enhancement. Eighty-five histologically proven DCIS (77 pure DCIS, eight microinvasive DCIS) were prospectively studied with MRI. The morphology of magnetic resonance enhancement and the kinetic curve was recorded. Histopathologically, intraductal lesions were classified according to Van Nuys score. Tumor microvascularity was immunohistochemically assessed in a subset of 24 DCIS evaluating the number of microvessels, microvascularity area, and microvascularity pattern (diffuse or periductal). On the mammogram, 74% of DCIS appeared as microcalcifications. On MRI, 70% of DCIS showed enhancement. Non-mass-like uptake was observed in 78% of cases. The mean size of nonenhancing carcinomas was significantly lower than that of enhancing carcinomas (p = 0.033). The diffuse pattern was more frequent than the periductal pattern. A significant relationship between the morphology of MR enhancement and the microvascularity pattern was observed (p = 0.036); thus, 90% of DCIS showing segmental enhancement on MRI displayed a diffuse pattern while all DCIS with ductal enhancement showed a periductal pattern. There was a significant relationship between the maximum area of microvascularity and the vascular pattern (p = 0.015); periductal patterns showed larger areas than diffuse patterns. The lesion size was significantly larger as the Van Nuys score increased (p < 0.001) and was also related to the number of microvessels (p = 0.012). The mean area of microvascularity of DCIS was significantly larger as the Van Nuys score increased (p = 0.02). Breast MRI helps depict the extent of DCIS and reveals its microvascular pattern.

Breast cancer cell-derived matrix supports vascular morphogenesis

The extracellular matrix (ECM), important for maintaining tissue homeostasis, is abnormally expressed in mammary tumors and additionally plays a crucial role in angiogenesis. We hypothesize that breast cancer cells (BCCs) deposit ECM that supports unique patterns of vascular morphogenesis of endothelial cells (ECs). Evaluation of ECM expression revealed that a nontumorigenic cell line (MCF10A), a tumorigenic cell line (MCF7), and a metastatic cell line (MDA-MB-231) express collagens I and IV, fibronectin, and laminin, with tenascin-C limited to MCF10A and MCF7. The amount of ECM deposited by BCCs was found to be higher in MCF10A compared with MCF7 and MDA231, with all ECM differing in their gross structure but similar in mean fiber diameter. Nonetheless, deposition of ECM from BCC lines was overall difficult to detect and insufficient to support capillary-like structure (CLS) formation of ECs. Therefore, a coculture approach was undertaken in which individual BCC lines were cocultured with fibroblasts. Variation in abundance of deposited ECM, deposition of ECM proteins, such as absent collagen I deposition from MDA231-fibroblast cocultures, and fibril organization was found. Deposited ECM from fibroblasts and each coculture supported rapid CLS formation of ECs. Evaluation of capillary properties revealed that CLS grown on ECM deposited from MDA231-fibroblast cocultures possessed significantly larger lumen diameters, occupied the greatest percentage of area, expressed the highest levels of von Willebrand factor, and expressed the greatest amount of E-selectin, which was upregulated independent of exposure to TNF-α. To our knowledge, this is the first study to report tumor cell ECM-mediated differences in vascular capillary features, and thus offers the framework for future investigations interrogating the role of the tumor ECM in supporting vascular morphogenesis.

Tumor angiogenesis: pericytes and maturation are not to be ignored

Angiogenesis, an essential component of tumor growth and survival, is regulated by complex interactions between several cell types and soluble mediators. Heterogeneous tumor vasculature originates from the collective effect of the nature of carcinoma and the complexity of the angiogenic network. Although the application of angiogenesis inhibitors in some types of cancers has shown clinical benefits, predictive markers to assess treatment effects have yet to be established. In this review, we focus on tumor vessel maturity as a potential marker for evaluating treatment response.

Control of VEGF expression in triple-negative breast carcinoma cells by suppression of SAF-1 transcription factor activity

Angiogenesis plays a significant role in cancer by providing increased blood supply to the affected tissues and thus bringing in growth factors, cytokines, and various nutrients for tumor growth. VEGF is the most prominent angiogenic agent that is markedly induced in cancer. Induction of VEGF has been widely studied but as cancer cells are quite adept at acquiring new alternative processes to circumvent surrounding environmental pressures, our understanding of the molecular mechanisms regulating VEGF expression in cancer, especially in triple-negative breast cancer cells, remains incomplete. Here, we present evidence of a novel mode of VEGF induction in triple-negative MDA-MB-231 breast cancer cells that is regulated by serum amyloid A activating factor 1 (SAF-1) transcription factor. Inhibition of SAF-1 by antisense short hairpin RNA profoundly reduces VEGF expression along with reduction in endothelial cell proliferation and migration. By both in vitro and in vivo molecular studies, we show that the effect of SAF-1 is mediated through its direct interaction with the VEGF promoter. In correlation, DNA-binding activity of SAF-1 is found to be significantly higher in MDA-MB-231 breast cancer cells. Examination of several breast cancer samples further revealed that SAF-1 is overexpressed in clinical breast cancer tissues. Taken together, these findings reveal that SAF-1 is a hitherto unrecognized participant in inducing VEGF expression in triple-negative breast cancer cells, an aggressive form of breast cancer that currently lacks effective treatment options. Suppression of SAF-1 activity in these cells can inhibit VEGF expression, providing a possible new method to control angiogenesis.

Radiologic-pathologic correlation of ductal carcinoma in situ

Ductal carcinoma in situ (DCIS) accounts for 20%-25% of breast cancers detected at screening mammography. The lesions are diverse and commonly are classified on the basis of their mammographic features and histologic characteristics such as nuclear grade and presence or absence of necrosis. The most common mammographic finding in DCIS is microcalcifications, but a low-grade lesion without necrosis is less likely to manifest with calcifications than either an intermediate- or a high-grade lesion. Other mammographic findings might include a mass or architectural distortion. Magnetic resonance (MR) imaging has higher sensitivity than mammography for the detection of DCIS and greater accuracy for depicting the extent of disease. The MR imaging appearance of DCIS depends primarily on the presence and extent of abnormal periductal or stromal vascularity. Nonmasslike enhancement, the most common MR imaging finding, is often seen in association with clumped internal enhancement. The enhancement kinetics in dynamic MR studies vary, and no kinetic pattern is pathognomonic of a particular nuclear grade of DCIS. However, the kinetic pattern at delayed imaging does appear to be correlated with the mammographic findings: Mass lesions show strong washout; fine pleomorphic, fine linear, and fine linear-branching calcifications demonstrate a plateau enhancement pattern; and amorphous calcifications exhibit persistent enhancement. Multidetector computed tomography might be a useful adjunct to MR imaging for preoperative mapping.

Heterogeneity of vascular and progenitor cell compartments in tumours from MMTV-PyVmT transgenic mice during mammary cancer progression

Transgenic mice are important tools for our study of breast cancer pathobiology. In order to evaluate changes in cell phenotype with breast cancer progression, we examined vascular and progenitor cell characteristics in tumours derived from MMTV-PyVmT mice. We performed dual-immunofluorescence staining for Tie2, pTie2Y1100, VEGFR2 and PDGFR-β and the pan-endothelial marker PECAM-1 (CD31) in 39 tumours from MMTV-PyVmT transgenic mice grouped by nuclear grade and tumour morphology. Immunohistochemical staining for Aldh1a1 was performed in MMTV-PyVmT-derived tumours and in non-transgenic mouse mammary glands. Tumour blood vessels were heterogeneous in all samples analysed, with the proportion of Tie2-, pTie2 (Y1100)-, VEGFR2- and PDGFR-β-positive tumour blood vessels ranging from 18-98%, 7-40%, 19-86% and 16-94% respectively. We observed a statistically significant difference in vascular pTie2Y1100 levels between low-nuclear-grade tumours and intermediate-/high-nuclear-grade tumours (P=0.03) and an increase in the proportion of PDGFR-β-positive tumour blood vessels in tumours with high vs. Intermediate-nuclear grade tumours (P<0.01). Aldh1a1-positive mammary epithelial cells were observed in the terminal end buds of non-transgenic mammary glands and Aldh1a1-positive mammary tumour cells were observed in tumours from MMTV-PyVmT transgenic mice. We observed a decrease in the average number of Aldh1a1-positive cells in tumours with a non-invasive vs. solid morphology (P=0.03), and in the average number of Aldh1a1-positive mammary tumour cells in low vs. intermediate and low vs. High-nuclear grade tumours (P<0.001). Our findings suggest heterogeneous expression of several molecules important for tumour angiogenesis and tumour progression that are currently under investigation as therapeutic targets for metastatic breast cancer.

AAV-P125A-endostatin and paclitaxel treatment increases endoreduplication in endothelial cells and inhibits metastasis of breast cancer

Endostatin potentiates the antimitotic effects of paclitaxel (taxol) on endothelial cells (ECs). P125A-endostatin and taxol-treated ECs showed multipolar spindles and nuclear lobulation, leading to mitotic catastrophe and cell death. Induction of nuclear abnormalities was found to be dependent on β-catenin levels as wnt-mediated overexpression of β-catenin reversed the changes in nuclear morphology. These results prompted us to investigate whether antiangiogenic gene therapy and paclitaxel chemotherapy can synergistically inhibit angiogenesis and tumor growth. We first determined the effect of combination treatment in a transgenic mouse model of breast cancer. Intramuscular injection of recombinant adeno-associated virus type-2 virus induced sustained expression of P125A-endostatin. In vivo studies showed that combination therapy inhibited mammary cancer growth, delayed the onset of multifocal mammary adenocarcinomas, decreased tumor angiogenesis and increased survival in treated mice. In a second model, female athymic mice were orthotopically transplanted with a metastatic human breast cancer cell line. Antiangiogenic gene therapy in combination with paclitaxel inhibited tumor angiogenesis and lung/lymph-node metastasis in this model. These studies demonstrate cooperation between endostatin gene therapy and chemotherapy to inhibit tumor initiation, growth and metastasis.

Antiangiogenic strategies in breast cancer management

Angiogenesis is considered one of the key mechanisms of tumour growth and survival. Therefore it represents an ideal pharmaceutical target. Many antiangiogenic agents have been developed so far in several solid tumours and also in breast cancer. Vascular endothelial growth factor (VEFG) is the main target and both monoclonal antibodies and small molecules belonging to the tyrosine kinase inhibitors directed against VEGF(R) have been developed. Some other therapeutic approaches have shown to exert some antiangiogenic activity, such as hormonal agents, metronomic chemotherapy, bisphosphonates and others. In this paper we provide an introduction of the current data supporting the angiogenesis in breast cancer and a review of the most relevant antiagiogenic therapies which have been investigated so far.

Vasohibin-1 as a potential predictor of aggressive behavior of ductal carcinoma in situ of the breast

Vasohibin-1 is a recently identified negative feedback regulator of angiogenesis induced by VEGF-A and bFGF. In this study, we first evaluated mRNA expression of vasohibin-1 and CD31 in 39 Japanese female breast carcinoma specimens including 22 invasive ductal carcinoma (IDC) and 17 ductal carcinoma in situ (DCIS) using a real-time quantitative RT-PCR (QRT-PCR) with LightCycler system. In addition, we also immunolocalized vasohibin-1 and CD31 and compared their immunoreactivity to nuclear grades and histological grades of 100 carcinoma cases (50 IDC and 50 DCIS). There were no statistically significant differences of CD31 mRNA expression and the number of CD31 positive vessels between DCIS and IDC (P = 0.250 and P = 0.191, respectively), whereas there was a statistically significant difference in vasohibin-1 mRNA expression and the number of vasohibin-1 positive vessels in DCIS and IDC (P = 0.022 and P < or = 0.001, respectively). There was a significant positive correlation between vasohibin-1 mRNA level and Ki-67 labeling index in DCIS (r(2) = 0.293, P < or = 0.001). In addition, vasohibin-1 mRNA expression was correlated with high nuclear and histological grades in DCIS cases and a significant positive correlation was detected between the number of vasohibin-1 positive vessels and Ki-67 labeling index or nuclear grade or Van Nuys classification of carcinoma cells (P < or = 0.001, respectively). These results all indicate the possible correlation between aggressive biological features in DCIS including increased tumor cell proliferation and the status of neovascularization determined by vasohibin-1 immunoreactivity.

Role of endothelial progenitor cells in breast cancer angiogenesis: from fundamental research to clinical ramifications

Blood vessel formation (neovascularization) in tumors can occur through two mechanisms: angiogenesis and vasculogenesis. Angiogenesis results from proliferation and sprouting of existing blood vessels close to the tumor, while vasculogenesis is believed to arise from recruitment of circulating cells, largely derived from the bone marrow, and de novo clonal formation of blood vessels from these cells. Increasing evidence in animal models indicate that bone marrow-derived endothelial precursor cells (EPC) can contribute to tumor angiogenesis. This review aims to collate existing literature and provide an overview on the current knowledge of EPC involvement in breast cancer angiogenesis. We also discuss recent attempts to use EPC as biomarker and therapeutic target in clinical trials.

Endothelial cell migration and vascular endothelial growth factor expression are the result of loss of breast tissue polarity

Recruiting a new blood supply is a rate-limiting step in tumor progression. In a three-dimensional model of breast carcinogenesis, disorganized, proliferative transformed breast epithelial cells express significantly higher expression of angiogenic genes compared with their polarized, growth-arrested nonmalignant counterparts. Elevated vascular endothelial growth factor (VEGF) secretion by malignant cells enhanced recruitment of endothelial cells (EC) in heterotypic cocultures. Significantly, phenotypic reversion of malignant cells via reexpression of HoxD10, which is lost in malignant progression, significantly attenuated VEGF expression in a hypoxia-inducible factor 1alpha-independent fashion and reduced EC migration. This was due primarily to restoring polarity: forced proliferation of polarized, nonmalignant cells did not induce VEGF expression and EC recruitment, whereas disrupting the architecture of growth-arrested, reverted cells did. These data show that disrupting cytostructure activates the angiogenic switch even in the absence of proliferation and/or hypoxia and restoring organization of malignant clusters reduces VEGF expression and EC activation to levels found in quiescent nonmalignant epithelium. These data confirm the importance of tissue architecture and polarity in malignant progression.

Angiogenesis in the progression of breast ductal proliferations

Angiogenesis, the formation of blood vessels, is necessary for a tumor to grow, but when angiogenesis first appears in the progression of breast ductal carcinomas is unknown. To determine when this occurs, the authors examined microvessel density (MVD) by CD31 and CD105 immunostaining in normal ducts, 32 cases of usual hyperplasia, 19 cases of atypical hyperplasia, and 29 cases of ductal carcinoma in situ (DCIS). Simple hyperplasia had a 22-fold greater MVD than normal ducts (P < .0001). An increase during the progression of ductal changes was highly significant (P < .0001). To determine a possible mechanism, immunohistochemistry for vascular endothelial growth factor (VEGF) was evaluated. VEGF staining intensity of ductal epithelium increased during the progression from normal to hyperplastic to DCIS. This study shows that the first significant increase in angiogenesis occurs very early in the evolution of ductal proliferations as ductal cells become hyperplastic.

Genetic ablation of caveolin-1 drives estrogen-hypersensitivity and the development of DCIS-like mammary lesions

Caveolin-1 (Cav-1) loss-of-function mutations are exclusively associated with estrogen receptor-positive (ER(+)) human breast cancers. To dissect the role of Cav-1 loss-of-function in the pathogenesis of human breast cancers, we used Cav-1(-/-) null mice as a model system. First, we demonstrated that Cav-1(-/-) mammary epithelia overexpress two well-established ER co-activator genes, CAPER and Foxa1, in addition to ER-alpha. Thus, the functional loss of Cav-1 may be sufficient to confer estrogen-hypersensitivity in the mammary gland. To test this hypothesis directly, we subjected Cav-1(-/-) mice to ovariectomy and estrogen supplementation. As predicted, Cav-1(-/-) mammary glands were hyper-responsive to estrogen and developed dysplastic mammary lesions with adjacent stromal angiogenesis that resemble human ductal carcinoma in situ. Based on an extensive biomarker analysis, these Cav-1(-/-) mammary lesions contain cells that are hyperproliferative and stain positively with nucleolar (B23/nucleophosmin) and stem/progenitor cell markers (SPRR1A and beta-catenin). Genome-wide transcriptional profiling identified many estrogen-related genes that were over-expressed in Cav-1(-/-) mammary glands, including CAPER--an ER co-activator gene and putative stem/progenitor cell marker. Analysis of human breast cancer samples revealed that CAPER is overexpressed and undergoes a cytoplasmic-to-nuclear shift during the transition from pre-malignancy to ductal carcinoma in situ. Thus, Cav-1(-/-) null mice are a new preclinical model for studying the molecular paradigm of estrogen hypersensitivity and the development of estrogen-dependent ductal carcinoma in situ lesions.

New potential and applications of contrast-enhanced ultrasound of the breast: Own investigations and review of the literature

Imaging of angiogenesis is a challenge for modern imaging. Velocimetry in malignant breast lesions and density of malignant vessels are very low. In breast imaging, first results of contrast-enhanced ultrasound (CEUS) were disappointing. Microbubbles are fragile when examined with high frequency US, commonly used in breast imaging. Second-generation contrast agents increase intensively the signal level of breast lesions and new sequences like CPS (Coherence Pulse Sequencing) might be accurate to detect malignant vessels in breast lesions for characterization, to assess the extent of infiltrative breast carcinoma or to evaluate the tumor response after chemotherapy. Another interesting clinical application is the differentiation between post-operative changes and recurrences. In this review, we detail the main results obtained with contrast ultrasonography in a characterization study. In malignant lesions, enhancement was fast, starting with less than 20s. Compared to MR, enhancement appeared faster. Malignant vessels were predominant in the external ring of the nodule, conversely vessels were seen in the center of the lesion in benign nodules. Malignant vessels were also seen outside the lesion. This knowledge could lead the surgeon to perform a larger lumpectomy in these cases, to obtain sane margins and to reduce recurrences.

Tamoxifen and aromatase inhibitors differentially affect vascular endothelial growth factor and endostatin levels in women with breast cancer

PURPOSE

Circulating and cellular proangiogenic and antiangiogenic proteins such as vascular endothelial growth factor (VEGF) and endostatin contribute to the local angiogenic balance. We explored the effects of tamoxifen and aromatase inhibitors on concentrations of VEGF and endostatin in plasma, serum, and platelet releasate (induced by platelet activation).

EXPERIMENTAL DESIGN

VEGF and endostatin concentrations were measured with a quantitative immunoassay before and after 1 to 5 weeks of treatment in 30 women with breast cancer treated with either tamoxifen (n = 14) or aromatase inhibitors (n = 16). Platelet activation was induced by a thrombin receptor agonist.

RESULTS

Tamoxifen therapy resulted in an increase in platelet releasate concentrations of VEGF (P = 0.01) but no change in plasma VEGF. In contrast, aromatase inhibitor therapy did not affect serum, plasma, or platelet releasate VEGF. In univariate analysis, aspirin use attenuated the tamoxifen-associated increase in VEGF in the platelet releasate and decreased serum levels of VEGF (P = 0.03). Aromatase inhibitor therapy resulted in a decrease in serum endostatin concentrations (P = 0.04), whereas plasma concentrations of endostatin tended to be higher during treatment with aromatase inhibitors (P = 0.06). Tamoxifen therapy resulted in no change in serum or plasma endostatin concentrations. Platelet releasate concentrations of endostatin did not change with either treatment. Interindividual variability was noted among both aromatase inhibitor--and tamoxifen-treated patients.

CONCLUSIONS

Tamoxifen and aromatase inhibitor therapy affect VEGF and endostatin levels and likely contribute to the angiogenic balance in breast cancer patients. Aspirin decreased the proangiogenic effects of tamoxifen, suggesting that antiplatelet and/or antiangiogenic therapy might improve the effectiveness of tamoxifen in women with breast cancer.

Osteotropic cancers: from primary tumor to bone

It has long been recognized that primary cancers spread to distant organs with characteristic preference. Bone metastases occur in approximately 70% of patients with advanced breast and prostate cancer, causing severe morbidity and hospitalization. In the last decade, we have gained a better understanding of the mechanisms by which certain tumor types tend to metastasize specifically to bone. It appears that the interaction between the organ microenvironment and cancer cells is fundamental for establishing metastatic growth. Accordingly, Stephen Paget's 'seed and soil' hypothesis - stating that circulating cancer cells (the 'seeds') disperse in all directions, but can accomplish metastases only in organs where the microenvironment (the 'soil') is permissive for their growth - still holds forth today. For this reason, this review uses the 'seed and soil' hypothesis as a template to discuss novel insight and developments in the bone metastasis field.

Breast tumour angiogenesis

The central importance of tumour neovascularization has been emphasized by clinical trials using antiangiogenic therapy in breast cancer. This review gives a background to breast tumour neovascularization in in situ and invasive breast cancer, outlines the mechanisms by which this is achieved and discusses the influence of the microenvironment, focusing on hypoxia. The regulation of angiogenesis and the antivascular agents that are used in an antiangiogenic dosing schedule, both novel and conventional, are also summarized.

Mechanisms of progression of ductal carcinoma in situ of the breast to invasive cancer. A hypothesis

Ductal carcinoma in situ (DCIS), a known precursor lesion of invasive cancer of the female breast, is surrounded by a thick basement membrane and a layer of myoepithelial cells. For DCIS to become invasive, both these barriers must be breached by cancer cells. It has been repeatedly suggested that proteolytic enzymes are somehow involved in this process but a direct proof of this event has never been provided. It is our hypothesis that invasion of the DCIS by capillary vessels derived from the periductal necklace of vessels is the most likely mechanism of breaching the basement membrane, providing an escape hatch for cancer cells. This hypothesis was initially tested on ten randomly selected cases of DCIS, with or without invasion. Capillary vessels were visualized by staining histologic sections with an antibody to CD 34 and, in three cases, by combined stain for CD 34 and collagen IV. In five of the 10 cases of DCIS, the presence of discrete capillary vessels invading DCIS could be documented. In two of these five cases, the vessels subdivided the cancerous ducts into territories of unequal sizes. Vascular invasion of DCIS is a plausible mechanism of breaching the basement membrane in DCIS as a prelude to invasion. This hypothesis must be further tested on a much larger number of cases. The hypothesis, if confirmed, may suggest that invasive cancer derived from DCIS may be prevented by antiangiogenic therapy.

Human chorionic gonadotropin as an angiogenic factor in breast cancer during pregnancy

Breast cancer associated with pregnancy is defined as the one in which the diagnosis is made in a pregnancy or within one year of delivery. Breast cancer is the second most common malignancy during pregnancy and it is generally considered to have a worse prognosis than the one that is not associated with pregnancy. The average patient is between 32 and 38 years of age. Steroid hormone receptor-positive cell populations comprise 80% of breast cancers, however, estrogen receptor levels in pregnancy-associated tumors are often low or absent. Extensive laboratory data suggest that angiogenesis plays an essential role in breast cancer development, invasion, and metastasis. One of the most powerful stimulatory factors, vascular endothelial growth factor (VEGF), functions in autocrine/paracrine pathways. Current research, generally has validated the poor prognosis and early relapse that are associated with increasing microvessel density, which is related to VEGF expression in tumoral cells. During pregnancy, human chorionic gonadotropin (hCG) induces neovascularization in various tissues, one of them being the placenta. Its receptors have been detected in epithelial cells in breast carcinoma tissue, and breast cancer cell lines. According to this premise the hCG normally produced during pregnancy could induce the synthesis of VEGF and by this means stimulate the development and metastatic potential of breast cancer cells in the pregnancy period. Thus, research involving hCG and VEGF would help us understand the physiopathology of breast cancer during pregnancy, as well as provide us with probable prognostic tools.

Efficient infection of tumor endothelial cells by a capsid-modified adenovirus

Targeted antiangiogenic gene therapy is an attractive approach to treat metastatic cancer. However, the relative paucity of the receptors of the commonly used adenovirus serotype 5 in endothelial cells as compared with liver cells undermines the use of this vector for targeting the endothelial cells in tumors. To overcome this problem, we analyzed the ability of a hybrid Ad5/35 virus, where the serotype 5 fiber has been replaced with the fiber from serotype 35, to target tumor vasculature. Infection of human umbilical vein endothelial cells (HUVECs) with Ad5/35 at MOI 120 infected 100% of cells. In contrast, infection with Ad5 at the same MOI infected only 10% HUVECs. Ad5/35 was even more effective in transducing human aortic endothelial cells (HAECs), as infection with Ad5/35 at MOI 3.6 was sufficient to transduce 95% of cells. Gene expression analyses demonstrated that infection of HUVECs and HAECs with Ad5/35 resulted in between 1 and 3 orders of magnitude higher gene expression than infection with Ad5. Furthermore, various liver-derived cells were less infectable with Ad5/35 than Ad5, indicating a favorable toxicity profile for this virus. In a rat colon carcinoma tumor model, Ad5 was located mainly in the liver parenchyma after hepatic artery administration. In contrast, Ad5/35 was found only in the angiogenesis-rich border region of the tumor. Double immunostaining revealed that Ad5/35 colocalized with CD31 and Flk-1 positive endothelial cells. These results indicate that Ad5/35 may be useful in anticancer strategies targeting tumor endothelial cells.

Phase I/pilot study of SU5416 (semaxinib) in combination with irinotecan/bolus 5-FU/LV (IFL) in patients with metastatic colorectal cancer

OBJECTIVES

Determine the toxicity, tolerability, and pharmacokinetics of SU5416, a vascular endothelial growth factor receptor-2 (VEGFR-2) tyrosine kinase inhibitor, coadministered with bolus 5-fluorouracil (5-FU), leucovorin, and irinotecan (IFL) in untreated patients with metastatic colorectal cancer.

METHODS

SU5416 (85 or 145 mg/m2) was administered twice weekly throughout a 6-week period along with standard IFL (4 weeks on/2 weeks off). Plasma samples were assayed for SU5416, irinotecan, and SN-38 by reverse-phase HPLC. Contrast enhanced, color Doppler sonography was performed on patients at the MTD to identify changes in tumor perfusion.

RESULTS

Eleven patients received treatment with SU5416 85 mg/m2 (n = 5) or 145 mg/m2 (n = 6). At 85 mg/m2, no DLTs were observed. At 145 mg/m2, grade 3 diarrhea and vomiting were observed during cycle 1; other grade 3 toxicities included fatigue, nausea, anorexia, anemia, pain, urinary retention, and hypertension. The pharmacokinetics of irinotecan and SN-38 were not altered by coadministration of SU5416. SU5416 pharmacokinetics were not altered by IFL. Contrast-enhanced, color Doppler sonography was performed on 2 patients and demonstrated reduced tumor perfusion after treatment in a patient who responded to treatment and increased perfusion in a patient who developed progressive disease. Three patients (27%) had confirmed partial responses, 2 patients (18%) had unconfirmed partial responses, and 4 patients (36%) had stable disease.

CONCLUSIONS

Twice weekly SU5416 can be administered with bolus IFL without unexpected toxicities or altering the pharmacokinetic behavior of the administered drugs. Changes in tumor blood perfusion can be detected by contrast-enhanced, color Doppler sonography. The further development of SU5416 was halted before this study was completed.

Magnetic resonance imaging reveals functional diversity of the vasculature in benign and malignant breast lesions

BACKGROUND

Tumor perfusion through the microvascular network can be imaged noninvasively by dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). The objective of the current study was to quantify the microvascular perfusion parameters in various human breast lesions and to determine whether they varied between benign lesions and malignancy and whether they were altered with increased invasiveness.

METHODS

Perfusion parameters in 22 benign fibrocystic changes, 15 ductal carcinomas in situ (DCIS), 30 infiltrating ductal carcinomas (IDC), and 22 fibroadenomas were measured using high-resolution DCE-MRI. Pixel-by-pixel image analysis yielded parametric images of two perfusion indicators: the influx transcapillary transfer constant (k(trans)) and the efflux transcapillary rate constant (k(ep)). Correlations of lesion type and perfusion parameters were calculated using Spearman correlation. Logistic regression analysis evaluated the best predictors of the kinetic parameters that differentiate between IDC and benign lesions.

RESULTS

The perfusion parameters exhibited a progressive increase from benign fibrocystic changes to DCIS and IDC, with a significant correlation between lesion type and the parameters' values (range of correlation coefficients, 0.56-0.76; P < 0.0001). In addition, k(trans) increased from low-grade DCIS to high-grade DCIS. Fibroadenomas were characterized uniquely by high k(trans) but low k(ep). Stepwise logistic regression selected k(trans) as the best predictor for distinguishing benign fibrocystic changes from IDC, yielding 93% sensitivity and 96% specificity.

CONCLUSIONS

The microvascular perfusion parameters in breast lesions were elevated with invasiveness. Quantification of these parameters using high-resolution DCE-MRI was helpful for differentiating between breast lesions and should improve breast carcinoma diagnosis.

Expression patterns of angiogenic and lymphangiogenic factors in ductal breast carcinoma in situ

The objective of this study was to investigate expression of various growth factors associated with angiogenesis and lymphangiogenesis and of their receptors in ductal carcinomas in situ of the breast (DCIS). We studied protein expression of basic fibroblast growth factor (bFGF), vascular endothelial growth factor (VEGF)-A, endothelin (ET)-1, and VEGF-C, and their receptors bFGF-R1, Flt-1, KDR, ET_AR, ET_BR, and Flt-4 immunohistochemically in 200 DCIS (pure DCIS: n=96; DCIS adjacent to an invasive component: n=104) using self-constructed tissue microarrays. Basic fibroblast growth factor-R1, VEGF-C, Flt-4, and ET_AR were expressed in the tumour cells in the majority of cases, whereas bFGF and Flt-1 expression was rarely observed. VEGF-A, KDR, ET-1, and ET_BR were variably expressed. The findings of VEGF-C and its receptor Flt-4 as lymphangiogenic factors being expressed in tumour cells of nearly all DCIS lesions and the observed expression of various angiogenic growth factors in most DCIS suggest that in situ carcinomas are capable of inducing angiogenesis and lymphangiogenesis. Moreover, we found a higher angiogenic activity in pure DCIS as compared to DCIS with concomitant invasive carcinoma. This association of angiogenic factors with pure DCIS was considerably more pronounced in the subgroup of non-high-grade DCIS (n=103) as compared with high-grade DCIS (n=94). Determination of these angiogenic markers may therefore facilitate discrimination between biologically different subgroups of DCIS and could help to identify a particularly angiogenic subset with a potentially higher probability of recurrence or of progression to invasiveness. For these DCIS, targeting angiogenesis may represent a feasible therapeutic approach for prevention of progression of DCIS to invasion.

Overexpression of beta1-chain-containing laminins in capillary basement membranes of human breast cancer and its metastases

INTRODUCTION

Laminins are the major components of vascular and parenchymal basement membranes. We previously documented a switch in the expression of vascular laminins containing the alpha4 chain from predominantly laminin-9 (alpha4beta2gamma1) to predominantly laminin-8 (alpha4beta1gamma1) during progression of human brain gliomas to high-grade glioblastoma multiforme. Here, differential expression of laminins was studied in blood vessels and ductal epithelium of the breast.

METHOD

In the present study the expressions of laminin isoforms alpha1-alpha5, beta1-beta3, gamma1, and gamma2 were examined during progression of breast cancer. Forty-five clinical samples of breast tissues including normal breast, ductal carcinomas in situ, invasive ductal carcinomas, and their metastases to the brain were compared using Western blot analysis and immunohistochemistry for various chains of laminin, in particular laminin-8 and laminin-9.

RESULTS

Laminin alpha4 chain was observed in vascular basement membranes of most studied tissues, with the highest expression in metastases. At the same time, the expression of laminin beta2 chain (a constituent of laminin-9) was mostly seen in normal breast and carcinomas in situ but not in invasive carcinomas or metastases. In contrast, laminin beta1 chain (a constituent of laminin-8) was typically found in vessel walls of carcinomas and their metastases but not in those of normal breast. The expression of laminin-8 increased in a progression-dependent manner. A similar change was observed from laminin-11 (alpha5beta2gamma1) to laminin-10 (alpha5beta1gamma1) during breast tumor progression. Additionally, laminin-2 (alpha2beta1gamma1) appeared in vascular basement membranes of invasive carcinomas and metastases. Chains of laminin-5 (alpha3beta3gamma2) were expressed in the ductal epithelium basement membranes of the breast and diminished with tumor progression.

CONCLUSION

These results suggest that laminin-2, laminin-8, and laminin-10 are important components of tumor microvessels and may associate with breast tumor progression. Angiogenic switch from laminin-9 and laminin-11 to laminin-8 and laminin-10 first occurs in carcinomas in situ and becomes more pronounced with progression of carcinomas to the invasive stage. Similar to high-grade brain gliomas, the expression of laminin-8 (and laminin-10) in breast cancer tissue may be a predictive factor for tumor neovascularization and invasion.

Biological inferences from a mathematical model of comedo ductal carcinoma in situ of the breast

The growth of a tumour in a duct is examined in order to model ductal carcinoma in situ (DCIS) of the breast, the earliest known stage of breast cancer. Interactions between the expansive forces created by tumour cell proliferation and the stresses that develop in the compliant basement membrane are studied using numerical and analytical techniques. Particular attention focuses on the impact that proteolytic enzymes have on the tumour's progression. As the tumour expands and the duct wall deforms, the tumour cells are subjected to mechanical and nutritional stresses caused by high pressures and oxygen deprivation. Such stresses may stimulate the cells to produce proteolytic enzymes that degrade the duct wall, making it more compliant and prone to penetration by the tumour cells. We use our model to compare these two hypotheses for enzyme production and find that mechanical stress is likely the dominant mechanism, with the wall deforming most at the centre of the duct. We then discuss the biological implications of our theoretical results and suggest possible directions for future work.

Histological quantitation of tumour angiogenesis

Tumours establish their blood supply via a number of processes in addition to angiogenesis. These include vasculogenesis, vascular remodelling, intussusception and possibly vascular mimicry in certain tumours. The mainstay of the assessment of tumour vascularity has been counting the number of immunohistochemically identified microvessels in vascular hot spots. Nevertheless, several other techniques are available, including Chalkley counting, vascular grade and the use of image analysis systems. Angiogenic activity can furthermore be assessed in histological samples by measuring the molecules involved in the establishment of the tumour vasculature, including angiogenic growth factors and their receptors, cell adhesion molecules, proteases and markers of activated, proliferating, cytokine stimulated or angiogenic vessels, such as CD105. Measuring the maturity of vessels may give an indication of the proportion of the tumour vasculature that is functional. Other reagents that can identify hypoxia-activated pathways are also being developed. The histological assessment of tumour vascularity is mainly used in the research setting but may also have applications in the clinic if appropriate methodology and trained observers perform the studies. Gene arrays may be able to provide an angiogenesis profile. Continued study into the processes involved in generating a tumour blood supply is likely to identify new markers that may be more accurate measures.

Breast cancer: the role of angiogenesis and antiangiogenic therapy

Angiogenesis plays a role in breast cancer development. Preclinical and clinical evidence is reviewed. Development of targeted antiangiogenic agents provides new challenges to clinical trial design. Current antiangiogenic therapy with traditional agents and novel agents are classified and reviewed.

Inhibition of VEGFR2 prevents DMBA-induced mammary tumor formation

Preinvasive mammary pathologies in humans and rat chemical carcinogenesis model systems have an increased microvascular density relative to normal tissue. This suggests the possibility of preventing invasive breast cancer by inhibiting angiogenesis. Vascular endothelial cell growth factor (VEGF) is a potent angiogenic growth factor, commonly involved in tumor-induced angiogenesis. Here, we show that both VEGF and VEGFR2 expression increase with histological progression to invasive disease in the rat 7,12-dimethylbenz[a]anthracene (DMBA) model. Other VEGF receptors, VEGFR1, neuropilin 1 and neuropilin 2, are constitutively expressed throughout progression. To examine whether VEGF signaling is functionally relevant to tumor-induced endothelial tubule formation in vitro and for tumor formation in vivo, we utilized the VEGFR2 inhibitor, ZD6474. In vitro endothelial cell tubulogenesis induced by isolated mammary organoids or carcinoma in situ from DMBA-treated rats is inhibited by ZD6474, in a dose-dependent fashion. The administration of ZD6474 to DMBA-treated rats inhibits the formation of atypical ductal hyperplasia and carcinoma in situ by greater than 95% (P < 0.05), when administered 1 week or 6 weeks post-DMBA initiation. Invasive disease was absent in all ZD6474 cohorts. These data support the hypothesis that progression of DMBA-induced preinvasive mammary pathologies to palpable disease requires angiogenesis via a VEGF-dependent mechanism.