CCNE1 and survival of patients with tubo-ovarian high-grade serous carcinoma: An Ovarian Tumor Tissue Analysis consortium study

BACKGROUND

Cyclin E1 (CCNE1) is a potential predictive marker and therapeutic target in tubo-ovarian high-grade serous carcinoma (HGSC). Smaller studies have revealed unfavorable associations for CCNE1 amplification and CCNE1 overexpression with survival, but to date no large-scale, histotype-specific validation has been performed. The hypothesis was that high-level amplification of CCNE1 and CCNE1 overexpression, as well as a combination of the two, are linked to shorter overall survival in HGSC.

METHODS

Within the Ovarian Tumor Tissue Analysis consortium, amplification status and protein level in 3029 HGSC cases and mRNA expression in 2419 samples were investigated.

RESULTS

High-level amplification (>8 copies by chromogenic in situ hybridization) was found in 8.6% of HGSC and overexpression (>60% with at least 5% demonstrating strong intensity by immunohistochemistry) was found in 22.4%. CCNE1 high-level amplification and overexpression both were linked to shorter overall survival in multivariate survival analysis adjusted for age and stage, with hazard stratification by study (hazard ratio [HR], 1.26; 95% CI, 1.08-1.47, p = .034, and HR, 1.18; 95% CI, 1.05-1.32, p = .015, respectively). This was also true for cases with combined high-level amplification/overexpression (HR, 1.26; 95% CI, 1.09-1.47, p = .033). CCNE1 mRNA expression was not associated with overall survival (HR, 1.00 per 1-SD increase; 95% CI, 0.94-1.06; p = .58). CCNE1 high-level amplification is mutually exclusive with the presence of germline BRCA1/2 pathogenic variants and shows an inverse association to RB1 loss.

CONCLUSION

This study provides large-scale validation that CCNE1 high-level amplification is associated with shorter survival, supporting its utility as a prognostic biomarker in HGSC.

Gene-Expression Profiling of Mucinous Ovarian Tumors and Comparison with Upper and Lower Gastrointestinal Tumors Identifies Markers Associated with Adverse Outcomes

PURPOSE

Advanced-stage mucinous ovarian carcinoma (MOC) has poor chemotherapy response and prognosis and lacks biomarkers to aid stage I adjuvant treatment. Differentiating primary MOC from gastrointestinal (GI) metastases to the ovary is also challenging due to phenotypic similarities. Clinicopathologic and gene-expression data were analyzed to identify prognostic and diagnostic features.

EXPERIMENTAL DESIGN

Discovery analyses selected 19 genes with prognostic/diagnostic potential. Validation was performed through the Ovarian Tumor Tissue Analysis consortium and GI cancer biobanks comprising 604 patients with MOC (n = 333), mucinous borderline ovarian tumors (MBOT, n = 151), and upper GI (n = 65) and lower GI tumors (n = 55).

RESULTS

Infiltrative pattern of invasion was associated with decreased overall survival (OS) within 2 years from diagnosis, compared with expansile pattern in stage I MOC [hazard ratio (HR), 2.77; 95% confidence interval (CI), 1.04-7.41, P = 0.042]. Increased expression of THBS2 and TAGLN was associated with shorter OS in MOC patients (HR, 1.25; 95% CI, 1.04-1.51, P = 0.016) and (HR, 1.21; 95% CI, 1.01-1.45, P = 0.043), respectively. ERBB2 (HER2) amplification or high mRNA expression was evident in 64 of 243 (26%) of MOCs, but only 8 of 243 (3%) were also infiltrative (4/39, 10%) or stage III/IV (4/31, 13%).

CONCLUSIONS

An infiltrative growth pattern infers poor prognosis within 2 years from diagnosis and may help select stage I patients for adjuvant therapy. High expression of THBS2 and TAGLN in MOC confers an adverse prognosis and is upregulated in the infiltrative subtype, which warrants further investigation. Anti-HER2 therapy should be investigated in a subset of patients. MOC samples clustered with upper GI, yet markers to differentiate these entities remain elusive, suggesting similar underlying biology and shared treatment strategies.

Moving with the Times: The Health Science Alliance (HSA) Biobank, Pathway to Sustainability

Human biobanks are recognised as vital components of translational research infrastructure. With the growth in personalised and precision medicine, and the associated expansion of biomarkers and novel therapeutics under development, it is critical that researchers can access a strong collection of patient biospecimens, annotated with clinical data. Biobanks globally are undertaking transformation of their operating models in response to changing research needs; transition from a ‘classic’ model representing a largely retrospective collection of pre-defined specimens to a more targeted, prospective collection model, although there remains a research need for both models to co-exist. Here we introduce the Health Science Alliance (HSA) Biobank, established in 2012 as a classic biobank, now transitioning to a hybrid operational model. Some of the past and current challenges encountered are discussed including clinical annotation, specimen utilisation and biobank sustainability, along with the measures the HSA Biobank is taking to address these challenges. We describe new directions being explored, going beyond traditional specimen collection into areas involving bioimages, microbiota and live cell culture. The HSA Biobank is working in collaboration with clinicians, pathologists and researchers, piloting a sustainable, robust platform with the potential to integrate future needs.

Impact of receptor phenotype on nodal burden in patients with breast cancer who have undergone neoadjuvant chemotherapy

Background

Optimal evaluation and management of the axilla following neoadjuvant chemotherapy (NAC) in patients with node‐positive breast cancer remains controversial. The aim of this study was to examine the impact of receptor phenotype in patients with nodal metastases who undergo NAC to see whether this approach can identify those who may be suitable for conservative axillary management.

Methods

Between 2009 and 2014, all patients with breast cancer and biopsy‐proven nodal disease who received NAC were identified from prospectively developed databases. Details of patients who had axillary lymph node dissection (ALND) following NAC were recorded and rates of pathological complete response (pCR) were evaluated for receptor phenotype.

Results

Some 284 patients with primary breast cancer and nodal metastases underwent NAC and subsequent ALND, including two with bilateral disease. The most common receptor phenotype was luminal A (154 of 286 tumours, 53·8 per cent), with lesser proportions accounted for by the luminal B–Her2 type (64, 22·4 per cent), Her2‐overexpressing (38, 13·3 per cent) and basal‐like, triple‐negative (30, 10·5 per cent) subtypes. Overall pCR rates in the breast and axilla were 19·9 per cent (54 of 271 tumours) and 37·4 per cent (105 of 281) respectively. Axillary pCR rates were highest in the Her2‐overexpressing group (27 of 35, 77 per cent) and lowest in the luminal A group (35 of 153, 22·9 per cent) (P < 0·001). Nodal burden (median number of positive nodes excised) was lower in the Her2‐overexpressing group compared with the luminal A group (0 versus 3; P < 0·001).

Conclusion

Her2 positivity was associated with increased rates of axillary pCR and reduced nodal burden following NAC.

Role of bone scan in addition to CT in patients with breast cancer selected for systemic staging

Background

The majority of women with breast cancer present with localized disease. The optimal strategy for identifying patients with metastatic disease at diagnosis remains unclear. The aim of this study was to evaluate the additional diagnostic yield from isotope bone scanning when added to CT staging of the thorax, abdomen and pelvis (CT-TAP) in patients with newly diagnosed breast cancer.

Methods

All patients diagnosed with breast cancer who underwent staging CT-TAP and bone scan between 2011 and 2013 were identified from a prospective database of a tertiary referral breast cancer centre that provides a symptomatic and population-based screening breast service. Criteria for staging included: biopsy-proven axillary nodal metastases; planned neoadjuvant chemotherapy or mastectomy; locally advanced or inflammatory breast cancer and symptoms suggestive of metastases.

Results

A total of 631 patients underwent staging by CT-TAP and bone scan. Of these, 69 patients (10·9 per cent) had distant metastasis at presentation, with disease confined to a single organ in 49 patients (71 per cent) and 20 (29 per cent) having metastatic deposits in multiple organs. Bone metastasis was the most common site; 39 of 49 patients had bone metastasis alone and 12 had a single isolated metastatic deposit. All but two of these were to the axial skeleton. No preoperative histological factors identified a cohort of patients at risk of metastatic disease. Omission of the bone scan in systemic staging would have resulted in a false-negative rate of 0·8 per cent.

Conclusion

For patients diagnosed with breast cancer, CT-TAP is a satisfactory stand-alone investigation for systemic staging.

New ASCO/CAP guideline recommendations for HER2 testing increase the proportion of reflex in situ hybridization tests and of HER2 positive breast cancers

Accurate determination of tumour human epidermal growth factor receptor type 2 (HER2) status is critical for optimal treatment of breast cancer. In October 2013, the American Society of Clinical Oncology (ASCO) and the College of American Pathologists (CAP) issued joint updated guideline recommendations for HER2 testing in breast cancer, with a revised algorithm for interpretation of immunohistochemistry (IHC) and in situ hybridisation (ISH) results. This study investigates the impact on HER2 IHC categorisation, implication for reflex ISH testing and potential for identification of false negative IHC. HER2 IHC preparations on 251 invasive breast tumours, originally reported according to 2007 guidelines, were re-scored using 2013 guidelines and the diagnostic categories compared. The results of ISH testing on a separate cohort of 32 breast tumours reported as HER2 IHC 2+ following the introduction of the 2013 guidelines, that would have been designated 1+ according to 2007, were reviewed. Application of 2013 guidelines resulted in a decrease in tumours classified as HER2 negative (83/251 vs 144/251) and a comparable increase in those classified as equivocal (2+) (139/251 vs 80/251). Relatively few tumours were re-classified as positive (29/251 vs 27/251). Furthermore, 3/32 breast cancer cases (HER2 IHC 2+ as per 2013 guidelines, 1+ using 2007 guidelines) were HER2 ISH positive. Application of the 2013 guidelines increases the HER2 IHC equivocal (2+) category and requirement for reflex ISH testing. The reduced threshold for ISH testing identifies some patients with HER2 positive breast cancer whose tumours would have been categorised as HER2 negative according to the 2007 guidelines.

ABCG1 is involved in vitamin E efflux

Vitamin E membrane transport has been shown to involve the cholesterol transporters SR-BI, ABCA1 and NPC1L1. Our aim was to investigate the possible participation of another cholesterol transporter in cellular vitamin E efflux: ABCG1. In Abcgl-deficient mice, vitamin E concentration was reduced in plasma lipoproteins whereas most tissues displayed a higher vitamin E content compared to wild-type mice. α- and γ-tocopherol efflux was increased in CHO cells overexpressing human ABCG1 compared to control cells. Conversely, α- and γ- tocopherol efflux was decreased in ABCG1-knockdown human cells (Hep3B hepatocytes and THP-1 macro- phages). Interestingly, α- and γ-tocopherol significantly downregulated ABCG1 and ABCA1 expression levels in Hep3B and THP-1, an effect confirmed in vivo in rats given vitamin E for 5 days. This was likely due to reduced LXR activation by oxysterols, as Hep3B cells and rat liver treated with vitamin E displayed a significantly reduced content in oxysterols compared to their respective controls. Overall, the present study reveals for the first time that ABCG1 is involved in cellular vitamin E efflux.

HDL particle size is a critical determinant of ABCA1-mediated macrophage cellular cholesterol export

RATIONALE

High-density lipoprotein (HDL) is a heterogeneous population of particles. Differences in the capacities of HDL subfractions to remove cellular cholesterol may explain variable correlations between HDL-cholesterol and cardiovascular risk and inform future targets for HDL-related therapies. The ATP binding cassette transporter A1 (ABCA1) facilitates cholesterol efflux to lipid-free apolipoprotein A-I, but the majority of apolipoprotein A-I in the circulation is transported in a lipidated state and ABCA1-dependent efflux to individual HDL subfractions has not been systematically studied.

OBJECTIVE

Our aims were to determine which HDL particle subfractions are most efficient in mediating cellular cholesterol efflux from foam cell macrophages and to identify the cellular cholesterol transporters involved in this process.

METHODS AND RESULTS

We used reconstituted HDL particles of defined size and composition, isolated subfractions of human plasma HDL, cell lines stably expressing ABCA1 or ABCG1, and both mouse and human macrophages in which ABCA1 or ABCG1 expression was deleted. We show that ABCA1 is the major mediator of macrophage cholesterol efflux to HDL, demonstrating most marked efficiency with small, dense HDL subfractions (HDL3b and HDL3c). ABCG1 has a lesser role in cholesterol efflux and a negligible role in efflux to HDL3b and HDL3c subfractions.

CONCLUSIONS

Small, dense HDL subfractions are the most efficient mediators of cholesterol efflux, and ABCA1 mediates cholesterol efflux to small dense HDL and to lipid-free apolipoprotein A-I. HDL-directed therapies should target increasing the concentrations or the cholesterol efflux capacity of small, dense HDL species in vivo.

Sphingomyelin phosphodiesterase acid-like 3A (SMPDL3A) is a novel nucleotide phosphodiesterase regulated by cholesterol in human macrophages

Cholesterol-loaded foam cell macrophages are prominent in atherosclerotic lesions and play complex roles in both inflammatory signaling and lipid metabolism, which are underpinned by large scale reprogramming of gene expression. We performed a microarray study of primary human macrophages that showed that transcription of the sphingomyelin phosphodiesterase acid-like 3A (SMPDL3A) gene is up-regulated after cholesterol loading. SMPDL3A protein expression in and secretion from primary macrophages are stimulated by cholesterol loading, liver X receptor ligands, and cyclic AMP, and N-glycosylated SMPDL3A protein is detectable in circulating blood. We demonstrate for the first time that SMPDL3A is a functional phosphodiesterase with an acidic pH optimum. We provide evidence that SMPDL3A is not an acid sphingomyelinase but unexpectedly is active against nucleotide diphosphate and triphosphate substrates at acidic and neutral pH. SMPDL3A is a major source of nucleotide phosphodiesterase activity secreted by liver X receptor-stimulated human macrophages. Extracellular nucleotides such as ATP may activate pro-inflammatory responses in immune cells. Increased expression and secretion of SMPDL3A by cholesterol-loaded macrophage foam cells in lesions may decrease local concentrations of pro-inflammatory nucleotides and potentially represent a novel anti-inflammatory axis linking lipid metabolism with purinergic signaling in atherosclerosis.

Abstract 230: Stimulation of Cholesterol Efflux from Human Macrophage by Liver X Receptor Agonists is a 2-Step Mechanism Requiring ARL7 and ABCA1

Nuclear Liver X Receptors activation by synthetic agonists was proven to be atheroprotective in mice; an effect likely based on stimulation of cellular cholesterol efflux from arterial macrophages. However, mechanisms involved in free cholesterol efflux from mouse macrophages appear distinct from those operating in human macrophages.

The objective of this study was to decipher precise cellular mechanisms controlling free cholesterol efflux from human macrophages upon LXR stimulation.

In THP-1 and human monocyte-derived macrophages (HMDM), treatment with the LXR agonist GW3965 efficiently induced ARL7 expression (6-fold, p<0.05), an effect associated with an increased amount of plasma membrane free cholesterol available for efflux (+25%, p<0.05) and a higher lipid rafts formation (+10%, p<0.05). Both effects were abolished in ARL7 Knockdown (KD) macrophages, leading to a lack of stimulation of cholesterol efflux by GW3965.

Specific targeting of each LXR isoforms, LXRα and LXRβ, by RNAi revealed that LXRα silencing in THP-1 and HMDM reduced significantly expression of cholesterol transporters ABCA1, ABCG1 and receptor SR-BI/Cla-1 mRNA levels, as well as free cholesterol efflux to apoA1 (-30%, p<0.05) and to HDL (-20%, p<0.05) upon stimulation with LXR, whereas LXRβ silencing has no impact. Interestingly, stimulation of cholesterol efflux to HDL by GW3965 was significantly reduced (-50%, p<0.05) in ABCA1 KD THP-1 macrophages; those cells being incapable to promote cholesterol efflux to apoA1. However, silencing of ABCG1 or SR-B1/Cla-1 had no impact on cholesterol efflux to HDL from either control or ABCA1 KD THP-1 macrophages treated or not with LXR agonist. By contrast stimulation of cholesterol efflux to HDL by GW3965 was completely abolished in LXRα/ABCA1 double KD macrophages, highlighting the major contribution of ABCA1 in cholesterol efflux from human macrophage.

We conclude that LXR-mediated stimulation of cholesterol efflux from human macrophages is a two-steps mechanism. First, LXR activation promotes ARL7-dependent free cholesterol transport to plasma membrane, mostly in lipid raft domains. Then, membrane free cholesterol is exported to apoA1 and HDL acceptors through ABCA1; this latter step being controlled selectively by LXRα.

Abstract P2-18-05: Axillary nodal burden in patients with a positive pre-operative ultrasound guided fine needle aspiration cytology

Introduction

Recent years have seen a dramatic shift to more conservative management of the axilla and the presence of a positive sentinel lymph node biopsy does not now automatically mandate an axillary clearance. This is based largely on data from the American College of Surgeons Oncology Group (ACOSOG) Z11 study, which failed to demonstrate a difference in local recurrence or overall survival when an axillary clearance was omitted in a highly selective group of patients with a positive sentinel lymph node. However, the presence of a positive pre-operative ultrasound guided axillary FNAC(Fine Needle Aspiration Cytology) may be representative of a higher burden of axillary disease.

Aim

Therefore, the aims of this study were firstly to quantify the actual nodal burden in breast cancer patients with a positive pre-operative ultrasound guided axillary FNAC and secondly to identify the number of patients who may have been spared an axillary clearance based on Z11 eligibility criteria.

Methods

A retrospective review of a prospectively maintained database within a tertiary breast cancer referral centre was performed. All patients with a positive pre-operative axillary FNAC were identified within a five year period (2007 – 2011). Demographic, tumour and biological characteristics and final nodal status were analysed. Eligibility for randomisation according to the Z11 criteria was assessed based on the final pathology and the number of patients who could have been spared an axillary clearance was identified.

Results

A total of 360 patients were identified with a positive axillary ultrasound guided FNAC. Sixty-three patients had no axillary surgery and three patients had recurrent disease, leaving a total of 294 for analysis. The mean age was 56 years (range 22 – 87). The mean size of the tumour was 31.3mm (range 4mm – 132mm) and the majority were an invasive grade 3 (57%) ductal carcinoma (84%). Luminal A (63%) was the commonest sub-type. The mean number of nodes removed at axillary clearance was 24 (range 7 – 58) while the mean number of positive nodes excised was 6 (range 0 – 47). Of these, the mean number of level I positive nodes was 4, level II was 1 and level III nodes was &lt;1.

Overall a total of 78 patients had less than three positive nodes identified in the axilla and potentially may have been eligible for the Z11 study. However, when patients who had a mastectomy, neo-adjuvant chemotherapy were excluded and the presence of extra-capsular nodal involvement was accounted for only 19 (6.4%) patients may have been spared an axillary clearance.

Conclusions

The presence of nodal positivity on a pre-operative FNAC is associated with a higher burden of axillary disease. Only a minority of these patients would be able to avoid an axillary clearance in the setting of the recent Z11 study. Performing an axillary ultrasound and FNAC of suspicious nodes allows patients to avoid an unnecessary sentinel lymph node biopsy and proceed directly to an axillary clearance.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P2-18-05.

Dyslipidemic diabetic serum increases lipid accumulation and expression of stearoyl-CoA desaturase in human macrophages

Type 2 diabetes and dyslipidemia are risk factors for cardiovascular disease. However, mechanisms by which hypertriglyceridemia influences atherogenesis remain unclear. We examined effects of dyslipidemic diabetic serum on macrophage lipid accumulation as a model of foam cell formation. Normal human macrophages were cultured in media supplemented with 10% serum from non-diabetic normolipidemic or non-diabetic hypercholesterolemic adults versus adults with Type 2 diabetes; diabetes and hypertriglyceridemia; or diabetes and hypercholesterolemia. Exposure to diabetic sera resulted in increased macrophage fatty acids (2-3 fold higher, both saturated and unsaturated). Macrophage expression of CD36, scavenger receptor A (SR-A) and stearoyl-CoA desaturase (SCD) was increased, most prominently in macrophages exposed to hypertriglyceridemic diabetic serum (twofold increase in CD36 and fourfold increase in SCD, p < 0.05). In these conditions, RNA inhibition of CD36 reduced macrophage free cholesterol (163.9 ± 10.5 vs. 221.9 ± 26.2 mmol free cholesterol/g protein, p = 0.04). RNA inhibition of SCD decreased macrophage fatty acid content, increased ABCA1 level and enhanced cholesterol efflux (18.0 ± 3.9 vs. 8.0 ± 0.8% at 48 h, p = 0.03). Diabetic dyslipidemia may contribute to accelerated atherosclerosis via alterations in macrophage lipid metabolism favoring foam cell formation. Increased expression of CD36 and SR-A would facilitate macrophage lipid uptake, while increased expression of SCD could block compensatory upregulation of ABCA1 and cholesterol efflux. Further studies are needed to clarify whether modulation of macrophage lipid metabolism might reduce progression of diabetic atherosclerosis.

Modulation of macrophage fatty acid content and composition by exposure to dyslipidemic serum in vitro

Macrophages in arterial walls accumulate lipids leading to the development of atherosclerotic plaques. However, mechanisms underlying macrophage lipid accumulation and foam cell formation are often studied without accounting for risk factors such as dyslipidemia. We investigated the effect of varying concentrations of triglyceride (TG) within physiological range on macrophage fatty acid (FA) accumulation and expression of cholesterol efflux proteins. Human monocytes were cultured in media supplemented with 10% sera containing low (0.7 mmol/L) to high (1.4 mmol/L) TG. The resulting macrophages were harvested after 10 days for analysis of FA content and composition and expression of genes involved in lipid metabolism. Exposure to higher TG and lower HDL concentrations in media increased macrophage lipid content. Macrophages exposed to higher TG had increased total FA content compared with controls (876 μg/mg protein vs. 652 μg/mg protein) and greater proportions of C16:0, C18:1 and C18:2. Macrophage expression of both ABCA1 and ABCG1 cholesterol efflux proteins were reduced when higher TG concentrations were present in the media. Expression of scavenger receptor CD36, involved in lipoprotein uptake, was also downregulated in macrophages exposed to higher TG. Culturing macrophages in conditions of higher versus lower TG influenced macrophage FA content and composition, and levels of regulatory proteins. Replicating in vitro levels of dyslipidemia encountered in vivo may provide an informative model for investigation of atherogenesis.

Clinicopathologic features of sentinel node metastases predictive of positive axillary clearance in grade 1 invasive breast carcinoma

BACKGROUND

Sentinel node (SN) biopsy is widely used to stage breast carcinoma and, when positive, typically leads to axillary clearance (AC).

AIMS

This study assesses clinicopathologic features of grade 1 breast carcinoma SNs with the aim of identifying a group of patients, who are likely to have a negative AC and can, therefore, safely be spared further surgery.

RESULTS

Two hundred and forty-seven patients with grade 1 invasive carcinoma were identified, of whom 29 had a positive SN. Four patients (13.8%) had a positive AC. Positive AC occurred in 3 of 6 (50%) patients whose SN showed extranodal extension (EE), but in only 1 of 23 (4.3%) patients without EE. All patients were staged as pN1(sn) following SN biopsy: only one, who had a 5.27 mm metastasis with EE, was pN2 following AC.

CONCLUSIONS

Extranodal extension is a significant predictor of a positive AC in this group. In its absence, AC did not alter the post-SN biopsy pN stage.

Sentinel lymph node biopsy in patients with a needle core biopsy diagnosis of ductal carcinoma in situ: is it justified?

BACKGROUND

The incidence of ductal carcinoma in situ (DCIS) has increased markedly with the introduction of population-based mammographic screening. DCIS is usually diagnosed non-operatively. Although sentinel lymph node biopsy (SNB) has become the standard of care for patients with invasive breast carcinoma, its use in patients with DCIS is controversial.

AIM

To examine the justification for offering SNB at the time of primary surgery to patients with a needle core biopsy (NCB) diagnosis of DCIS.

METHODS

A retrospective analysis was performed of 145 patients with an NCB diagnosis of DCIS who had SNB performed at the time of primary surgery. The study focused on rates of SNB positivity and underestimation of invasive carcinoma by NCB, and sought to identify factors that might predict the presence of invasive carcinoma in the excision specimen.

RESULTS

7/145 patients (4.8%) had a positive sentinel lymph node, four macrometastases and three micrometastases. 6/7 patients had invasive carcinoma in the final excision specimen. 55/145 patients (37.9%) with an NCB diagnosis of DCIS had invasive carcinoma in the excision specimen. The median invasive tumour size was 6 mm. A radiological mass and areas of invasion <1 mm, amounting to "at least microinvasion" on NCB were predictive of invasive carcinoma in the excision specimen.

CONCLUSIONS

SNB positivity in pure DCIS is rare. In view of the high rate of underestimation of invasive carcinoma in patients with an NCB diagnosis of DCIS in this study, SNB appears justified in this group of patients.

Independent protective roles for macrophage Abcg1 and Apoe in the atherosclerotic lesion development

OBJECTIVE

ATP-binding cassette transporter G1 (Abcg1) and apolipoprotein E (Apoe) play a role in macrophage cholesterol efflux and consequently the development of atherosclerosis. A possible interaction between Abcg1 and Apoe in cholesterol efflux was postulated, but the potential combined action of these proteins on atherosclerotic lesion formation is unclear.

METHODS

LDL receptor knockout (KO) mice were transplanted with bone marrow from Abcg1/Apoe double KO (dKO) mice, their respective single knockouts, and wild-type (WT) controls and challenged with a high-fat/high-cholesterol diet for 6 weeks to induce atherosclerosis.

RESULTS

No differences were found in serum lipid levels. The mean atherosclerotic lesion area in dKO transplanted animals (187+/-18x10(3)microm(2)) was 1.4-fold (p<0.01) increased compared to single knockouts (Abcg1 KO: 138+/-5x10(3)microm(2); Apoe KO: 131+/-7x10(3)microm(2)) and 1.9-fold (p<0.001) as compared to WT controls (97+/-15x10(3)microm(2)). In vitro cholesterol efflux experiments established that combined deletion of Abcg1 and Apoe leads to a larger attenuation of macrophage cholesterol efflux to HDL as compared to single knockouts.

CONCLUSIONS

Single deletion of macrophage Abcg1 or Apoe does lead to a moderate non-significant increase in atherosclerotic lesion development as tested by ANOVA, while combined deletion of Abcg1 and Apoe induces a more dramatic and significant increase in atherosclerosis. Our results indicate an additive, independent effect for both macrophage Abcg1 and Apoe in the prevention of atherosclerosis.

Endogenous 24(S),25-epoxycholesterol fine-tunes acute control of cellular cholesterol homeostasis

Certain oxysterols, when added to cultured cells, are potent regulators of cholesterol homeostasis, decreasing cholesterol synthesis and uptake and increasing cholesterol efflux. However, very little is known about whether or not endogenous oxysterol(s) plays a significant role in cholesterol homeostasis. 24(S),25-Epoxycholesterol (24,25EC) is unique among oxysterols in that it is produced in a shunt of the mevalonate pathway which also produces cholesterol. We investigated the role of endogenously produced 24,25EC using a novel strategy of overexpressing the enzyme 2,3-oxidosqualene cyclase in Chinese hamster ovary cells to selectively inhibit the synthesis of this oxysterol. First, loss of 24,25EC decreased expression of the LXR target gene, ABCA1, substantiating its role as an endogenous ligand for LXR. Second, loss of 24,25EC increased acute cholesterol synthesis, which was rationalized by a concomitant increase in HMG-CoA reductase gene expression at the level of SREBP-2 processing. Therefore, in the absence of 24,25EC, fine-tuning of the acute regulation of cholesterol homeostasis is lost, supporting the hypothesis that 24,25EC functions to protect the cell against the accumulation of newly synthesized cholesterol.

The effect of statins on ABCA1 and ABCG1 expression in human macrophages is influenced by cellular cholesterol levels and extent of differentiation

The ATP-binding cassette transporters, ABCA1 and ABCG1, are LXR-target genes that participate in the removal of cholesterol from lipid-laden macrophages, a crucial anti-atherogenic mechanism. Statins are currently the most efficacious therapy for the treatment of hypercholesterolemia and cardiovascular disease. We and others have shown that statins decrease ABCA1 and ABCG1 expression as well as cholesterol efflux from human macrophages. However, other studies have reported that statins produce no change, or even a modest increase in these variables. In an attempt to reconcile these conflicting reports, we investigated how the effect of statins on transcription of ABCA1 and ABCG1 is modulated by cellular cholesterol status and the extent of macrophage differentiation. We showed that supplementing human macrophages with cholesterol reversed the statin-mediated down-regulation of ABC transporter expression whereas depletion of cellular cholesterol tended to accentuate the statin effect. Down-regulation of ABC transporter expression was more pronounced with increased macrophage differentiation status and already evident at statin concentrations equivalent to those present in plasma. Addition of LXR agonists, which are currently on trial as anti-atherogenic agents, reversed the effects on ABC transporter expression while PPAR alpha and PPAR gamma agonists did not. The significance of these results in light of current and future combination therapies is discussed.

Synthesis of the oxysterol, 24(S), 25-epoxycholesterol, parallels cholesterol production and may protect against cellular accumulation of newly-synthesized cholesterol

AIM

The effects of 24(S),25-epoxycholesterol (24,25EC) on aspects of cholesterol homeostasis is well-documented. When added to cells, 24,25EC decreases cholesterol synthesis and up-regulates cholesterol efflux genes, including ABCA1. Synthesis of 24,25EC occurs in a shunt of the mevalonate pathway which also produces cholesterol. Therefore, 24,25EC synthesis should be subject to the same negative feedback regulation as cholesterol synthesis. To date, no role has been ascribed to 24,25EC in light of the fact that increased accumulation of cholesterol should decrease formation of this oxysterol through feedback inhibition. This leads to the intriguing paradox: why inhibit production of an apparently important regulator of cholesterol homeostasis when it is needed most?

METHODS

We used a combination of pharmacological and genetic approaches in Chinese Hamster Ovary cell-lines to investigate this paradox. Endogenous synthesis of 24,25EC was manipulated using partial inhibition of the enzyme, Oxidosqualene Cyclase. Changes in cholesterol and 24,25EC synthesis were determined using metabolic labelling with [1-14C]-acetate, thin-layer chromatography and phosphorimaging. Transcriptional effects mediated via SREBP and LXR were analysed by luciferase reporter assays.

RESULTS

We showed that cholesterol addition to cells lead to a rapid and preferential inhibition of 24,25EC synthesis. Addition of 24,25EC resulted in parallel inhibition of 24,25EC and cholesterol synthesis. Furthermore, we used a variety of approaches to examine the relationship between cholesterol and 24,25EC synthesis, including cell-lines with different rates of cholesterol synthesis, varying cholesterol synthetic rates by pre-treatment with a statin, or lipoprotein cholesterol loading of macrophages. In all cases, we showed that 24,25EC synthesis faithfully tracked cholesterol synthesis. Moreover, changes in 24,25EC synthesis exerted downstream effects, reducing SREBP transcriptional activity whilst increasing ABCA1 and LXR transcriptional activity.

CONCLUSION

Our results show that 24,25EC synthesis parallels cholesterol synthesis, consistent with this oxysterol functioning as a safety valve to protect against the accumulation of newly-synthesised cholesterol (as opposed to exogenously-derived cholesterol). Considering that 24,25EC is capable of being produced in all cholesterogenic cells, we propose that production of 24,25EC may represent a ubiquitous defence mechanism.

Radial scars/complex sclerosing lesions and malignancy in a screening programme: incidence and histological features revisited

AIMS

Radial scars (RS) are benign entities, frequently identified on screening mammography, which may be associated with malignancy. Much debate has been generated with regard to the optimum management of RS. We present our experience of RS in the first 5 years of a screening programme. The aim was to evaluate (i) the incidence of atypia and malignancy and (ii) the value of the preoperative core biopsy. We also further characterize the histological features.

METHODS AND RESULTS

One hundred and twenty-five histologically confirmed cases of RS were reviewed (111 had preoperative biopsies). Thirty-one (24.8%) patients had a final malignant diagnosis (11 with invasive malignancy) and 28 (22.4%) showed atypia (including lobular carcinoma in situ). In those with core biopsies and a final malignant diagnosis, 12 cases were categorized as B5 (41.3%), three as B4 (10.3%), 12 as B3 (41.3%) and two as B2 (7%). Common histological features included obliterated ducts and chronic inflammation with, less frequently, neural hyperplasia (16.8%) and perineural invasion (3.2%).

CONCLUSIONS

The high incidence of atypia and malignancy identified in our study justifies our policy of removing all mammographically detected RS. We emphasize the utility of preoperative core biopsy evaluation in permitting one-stage surgical therapy in those with B5 diagnoses.

Inhibition of atherosclerosis by the serine palmitoyl transferase inhibitor myriocin is associated with reduced plasma glycosphingolipid concentration

Glycosphingolipids (GSL) have been implicated as potential atherogenic lipids. Inhibition of hepatic serine palmitoyl transferase (SPT) reduces plasma sphingomyelin (SM) levels in the absence of changes in cholesterol or triglyceride (TG) concentration and this leads to a reduction of atherosclerosis in apolipoprotein-E gene knockout (apoE(-/-)) mice. The possibility that the reduced atherosclerosis resulting from SPT inhibition is associated with decreases in plasma GSL concentration has not been examined and was the primary aim of this investigation. We show that intraperitoneal delivery of the SPT inhibitor myriocin for 9 weeks inhibits atherosclerosis in apoE(-/-) mice fed a high fat diet. Lesion inhibition was most pronounced at the aortic arch and distal sites of the thoracic and abdominal aorta. There was also a trend towards a reduction in lesion area at the aortic root. Myriocin treatment resulted in significant reductions in both plasma SM and GSL concentration of 42% and 25%, as assessed by enzymatic and HPLC methods, respectively. Moreover, SM and GSL concentrations were significantly correlated, indicating that SPT inhibition suppresses the synthesis of both these sphingolipids concomitantly. The inhibition of atherosclerosis induced by myriocin was not associated with changes in plasma cholesterol or TG concentrations or lipoprotein profiles as determined by FPLC. These data indicate that therapeutic reduction of plasma SM and/or GSL concentrations may offer a novel treatment for atherosclerosis.

Diagnostic accuracy of core biopsy for ductal carcinoma in situ and its implications for surgical practice

BACKGROUND

Core biopsy is considered to be a highly accurate method of gaining a preoperative histological diagnosis of breast cancer. Ductal carcinoma in situ (DCIS) is often impalpable and is a more subtle form of breast cancer.

AIM

To investigate the accuracy of core biopsy in the diagnosis of cancer in patients with DCIS.

METHODS

All patients who had invasive cancer (n = 959) or DCIS (n = 92) that was confirmed by excision between 1999 and 2004 were identified. The diagnostic methods, histology of the core biopsy specimen and excision histology were reviewed in detail.

RESULTS

Core biopsy was attempted in 88% (81/92) of patients with DCIS and in 91% (874/959) of those with invasive disease. Of those patients who underwent core biopsy, a diagnosis of carcinoma on the initial core was made in 65% (53/81) of patients with DCIS compared with 92% (800/874) of patients with invasive disease (p<0.0001). Smaller lesion size (p = 0.005) and lower grade (p = 0.03) were associated with increased risk for a negative or non-diagnostic core in patients with DCIS. The nature of the mammographic lesion or the method of biopsy did not affect the probability of an accurate core biopsy. Patients who had a preoperative diagnosis of DCIS by core biopsy had a reoperation rate of 36% compared with 65% of those that did not have a preoperative diagnosis (p = 0.007).

CONCLUSION

Although core biopsies are highly accurate forms of obtaining a preoperative diagnosis in patients with invasive breast cancer, this is not the case in DCIS. As the number of surgical procedures can be reduced by core biopsy, it is still of considerable value in the management of DCIS.

Impact of a national external quality assessment scheme for breast pathology in the UK

BACKGROUND

This article presents the results and observed effects of the UK National Health Service Breast Screening Programme (NHSBSP) external quality assurance scheme in breast histopathology.

AIMS/METHODS

The major objectives were to monitor and improve the consistency of diagnoses made by pathologists and the quality of prognostic information in pathology reports. The scheme is based on a twice yearly circulation of 12 cases to over 600 registered participants. The level of agreement was generally measured using kappa statistics.

RESULTS

Four main situations were encountered with respect to diagnostic consistency, namely: (1) where consistency is naturally very high-this included diagnosing in situ and invasive carcinomas (and certain distinctive subtypes) and uncomplicated benign lesions; (2) where the level of consistency was low but could be improved by making guidelines more detailed and explicit-this included histological grading; (3) where consistency could be improved but only by changing the system of classification-this included classification of ductal carcinoma in situ; and (4) where no improvement in consistency could be achieved-this included diagnosing atypical hyperplasia and reporting vascular invasion. Size measurements were more consistent for invasive than in situ carcinomas. Even in cases where there is a high level of agreement on tumour size, a few widely outlying measurements were encountered, for which no explanation is readily forthcoming.

CONCLUSIONS

These results broadly confirm the robustness of the systems of breast disease diagnosis and classification adopted by the NHSBSP, and also identify areas where improvement or new approaches are required.

The NHS breast screening programme (pathology) EQA: experience in recent years relating to issues involved in individual performance appraisal

BACKGROUND

The original role of the National Health Service breast screening programme (pathology) external quality assessment (EQA) scheme was educational; it aimed to raise standards, reinforce use of common terminology, and assess the consistency of pathology reporting of breast disease in the UK.

AIMS/METHODS

To examine the performance (scores) of pathologists participating in the scheme in recent years. The scheme has evolved to help identify poor performers, reliant upon setting an acceptable cutpoint. Therefore, the effects of different cutpoint strategies were evaluated and implications discussed.

RESULTS/CONCLUSIONS

Pathologists who joined the scheme improved over time, particularly those who did less well initially. There was no obvious association between performance and the number of breast cancer cases reported each year. This is not unexpected because the EQA does not measure expertise, but was established to demonstrate a common level of performance (conformity to consensus) for routine cases, rather than the ability to diagnose unusual/difficult cases. A new method of establishing cutpoints using interquartile ranges is proposed. The findings also suggest that EQA can alter a pathologist's practice: those who leave the scheme (for whatever reason) have, on average, marginally lower scores. Consequently, with the cutpoint methodology currently used (which is common to several EQA schemes) there is the potential for the cutpoint to drift upwards. In future, individuals previously deemed competent could subsequently be erroneously labelled as poor performers. Due consideration should be given to this issue with future development of schemes.

Glycosphingolipid Accumulation Inhibits Cholesterol Efflux via the ABCA1/Apolipoprotein A-I Pathway

Cellular glycosphingolipid (GSL) storage is known to promote cholesterol accumulation. Although physical interactions between GSLs and cholesterol are thought to cause intracellular cholesterol "trapping," it is not known whether cholesterol homeostatic mechanisms are also impaired under these conditions. ApoA-I-mediated cholesterol efflux via ABCA1 (ATP-binding cassette transporter A1) is a key regulator of cellular cholesterol balance. Here, we show that apoA-I-mediated cholesterol efflux was inhibited (by up to 53% over 8 h) when fibroblasts were treated with lactosylceramide or the glucocerebrosidase inhibitor conduritol B epoxide. Furthermore, apoA-I-mediated cholesterol efflux from fibroblasts derived from patients with genetic GSL storage diseases (Fabry disease, Sandhoff disease, and GM1 gangliosidosis) was impaired compared with control cells. Conversely, apoA-I-mediated cholesterol efflux from fibroblasts and cholesterol-loaded macrophage foam cells was dose-dependently stimulated (by up to 6-fold over 8 h) by the GSL synthesis inhibitor 1-phenyl-2-decanoylamino-3-morpholino-1-propanol (PDMP). Unexpectedly, a structurally unrelated GSL synthesis inhibitor, N-butyldeoxynojirimycin, was unable to stimulate apoA-I-mediated cholesterol efflux despite achieving similar GSL depletion. PDMP was found to up-regulate ABCA1 mRNA and protein expression, thereby identifying a contributing mechanism for the observed acceleration of cholesterol efflux to apoA-I. This study reveals a novel defect in cellular cholesterol homeostasis induced by GSL storage and identifies PDMP as a new agent for enhancing cholesterol efflux via the ABCA1/apoA-I pathway.

Surgical intervention in screen-detected patients versus symptomatic patients with breast cancer

OBJECTIVES

The impact of population-based screening for breast cancer on the rate of breast-conserving surgery has not been established. We sought to evaluate whether surgical intervention in patients with screen-detected breast cancer differed from those with clinically detected tumours.

SETTINGS

St Vincent's University Hospital and the BreastCheck Merrion Unit, part of the Irish National Breast Screening Programme, were the setting for the study.

METHODS

A total of 902 patients referred for surgery to St Vincent's University Hospital over a four-year period (2000-2003) were studied. Patients with breast cancers detected during the prevalent round of screening (n=325) were compared with patients presenting with symptomatic disease (n=577). The operative procedure, nature of axillary surgery and histopathological findings were recorded in each case.

RESULTS

There was an increase in breast-conserving therapy in the screened population compared with symptomatic cases (68% screened versus 53% symptomatic; p<0.0001), with a corresponding reduction in axillary clearance rates (65% screened versus 81% symptomatic; p<0.0001). Nodal positivity was similar following correction for size in all tumours >1 cm, regardless of method of detection. Sentinel node biopsy was successfully undertaken in 39% of tumours <2 cm (T1 tumours) [corrected] in the screening population.

CONCLUSIONS

The screened population was statistically more likely to have breast-conserving therapy than the symptomatic group. Sentinel node biopsy has evolved into an acceptable alternative to axillary clearance in T1 cancers, particularly in screen-detected cases.

Statins inhibit synthesis of an oxysterol ligand for the liver x receptor in human macrophages with consequences for cholesterol flux

OBJECTIVE

Cholesterol efflux from macrophages in the artery wall, a key cardioprotective mechanism, is largely coordinated by the nuclear oxysterol-activated liver X receptor, LXRalpha. We investigated the effect of statins on LXR target gene expression and cholesterol efflux from human macrophages.

METHODS AND RESULTS

In human macrophages (THP-1 cell line and primary cells), the archetypal statin, compactin, greatly reduced mRNA levels of 2 LXR target genes, ABCA1 and ABCG1 mRNA, as well as decreased cholesterol efflux. Commonly prescribed statins also downregulated LXR target gene expression in THP-1 cells. We provide several lines of evidence indicating that statins decrease expression of LXR target genes by inhibiting the synthesis of an oxysterol ligand for LXR, 24(S),25-epoxycholesterol. When THP-1 cells were cholesterol-loaded via incubation with acetylated low-density lipoprotein, synthesis of 24(S),25-epoxycholesterol was greatly reduced and the downregulatory effect of compactin on ABCA1 mRNA levels and cholesterol efflux was lost.

CONCLUSIONS

Our results suggest that statins may downregulate cholesterol efflux from nonloaded human macrophages by inhibiting synthesis of an oxysterol ligand for LXR. Further work is needed to determine how relevant our observations are to arterial foam cells in vivo.

Induction of fibroblast apolipoprotein E expression during apoptosis, starvation-induced growth arrest and mitosis

Apolipoprotein E (apoE) mediates the hepatic clearance of plasma lipoproteins, facilitates cholesterol efflux from macrophages and aids neuronal lipid transport. ApoE is expressed at high levels in hepatocytes, macrophages and astrocytes. In the present study, we identify nuclear and cytosolic pools of apoE in human fibroblasts. Fibroblast apoE mRNA and protein levels were up-regulated during staurosporine-induced apoptosis and this was correlated with increased caspase-3 activity and apoptotic morphological alterations. Because the transcription of apoE and specific pro-apoptotic genes is regulated by the nuclear receptor LXR (liver X receptor) alpha, we analysed LXRalpha mRNA expression by quantitative real-time PCR and found it to be increased before apoE mRNA induction. The expression of ABCA1 (ATP-binding cassette transporter A1) mRNA, which is also regulated by LXRalpha, was increased in parallel with apoE mRNA, indicating that LXRalpha probably promotes apoE and ABCA1 transcription during apoptosis. Fibroblast apoE levels were increased under conditions of serum-starvation-induced growth arrest and hyperoxia-induced senescence. In both cases, an increased nuclear apoE level was observed, particularly in cells that accumulated lipofuscin. Nuclear apoE was translocated to the cytosol when mitotic nuclear disassembly occurred and this was associated with an increase in total cellular apoE levels. ApoE amino acid sequence analysis indicated several potential sites for phosphorylation. In vivo studies, using 32P-labelling and immunoprecipitation, revealed that fibroblast apoE can be phosphorylated. These studies reveal novel associations and potential roles for apoE in fundamental cellular processes.

Intraoperative margin assessment and re-excision rate in breast conserving surgery

AIM

The aim of this study was to assess the efficacy of intraoperative margin assessment in obtaining clear margins in conserving surgery for breast cancer.

METHODS

Two hundred and twenty patients undergoing wide local excision (WLE) for core biopsy proven primary invasive breast cancer, during a 30 months period, were included in the study. Following surgical excision the breast specimen was orientated with sutures, inked using India ink and coloured pigments and incised to identify the tumour, maintaining orientation. The distance to the individual radial margins were estimated macroscopically by the pathologist and conveyed intraoperatively to the surgeon. A macroscopic tumour-margin distance of less than 10 mm was considered compromised and the margin(s) in question was then excised if feasible.

RESULTS

Eighty-one patients (37%) were judged to have compromised margins following intraoperative macroscopic evaluation and had at least one margin re-excised. Sixteen of the 81 patients (20%) in this subgroup had compromised margins on microscopy and required a second operation. One hundred and thirty-nine patients (63%) were deemed to have clear margins intraoperatively, subsequently confirmed on microscopic examination in 135 patients (97%). Intraoperative macroscopic assessment of margin status was associated with 9.1% of patients requiring a second operation. In the absence of intraoperative assessment of margin status a further 47 patients (21.4%) would have required a second operation.

CONCLUSION

Intraoperative macroscopic margin assessment is an effective technique in reducing the number of second operative procedures in patients undergoing conserving surgery for primary invasive breast cancer.

Apolipoprotein A-I-stimulated apolipoprotein E secretion from human macrophages is independent of cholesterol efflux

Apolipoprotein A-I (apoA-I)-mediated cholesterol efflux involves the binding of apoA-I to the plasma membrane via its C terminus and requires cellular ATP-binding cassette transporter (ABCA1) activity. ApoA-I also stimulates secretion of apolipoprotein E (apoE) from macrophage foam cells, although the mechanism of this process is not understood. In this study, we demonstrate that apoA-I stimulates secretion of apoE independently of both ABCA1-mediated cholesterol efflux and of lipid binding by its C terminus. Pulse-chase experiments using (35)S-labeled cellular apoE demonstrate that macrophage apoE exists in both relatively mobile (E(m)) and stable (E(s)) pools, that apoA-I diverts apoE from degradation to secretion, and that only a small proportion of apoA-I-mobilized apoE is derived from the cell surface. The structural requirements for induction of apoE secretion and cholesterol efflux are clearly dissociated, as C-terminal deletions in recombinant apoA-I reduce cholesterol efflux but increase apoE secretion, and deletion of central helices 5 and 6 decreases apoE secretion without perturbing cholesterol efflux. Moreover, a range of 11- and 22-mer alpha-helical peptides representing amphipathic alpha-helical segments of apoA-I stimulate apoE secretion whereas only the C-terminal alpha-helix (domains 220-241) stimulates cholesterol efflux. Other alpha-helix-containing apolipoproteins (apoA-II, apoA-IV, apoE2, apoE3, apoE4) also stimulate apoE secretion, implying a positive feedback autocrine loop for apoE secretion, although apoE4 is less effective. Finally, apoA-I stimulates apoE secretion normally from macrophages of two unrelated subjects with genetically confirmed Tangier Disease (mutations C733R and c.5220-5222delTCT; and mutations A1046D and c.4629-4630insA), despite severely inhibited cholesterol efflux. We conclude that apoA-I stimulates secretion of apoE independently of cholesterol efflux, and that this represents a novel, ABCA-1-independent, positive feedback pathway for stimulation of potentially anti-atherogenic apoE secretion by alpha-helix-containing molecules including apoA-I and apoE.

Factors affecting metastases to non-sentinel lymph nodes in breast cancer

AIMS

Because sentinel lymph node (SLN) biopsy for breast cancer has become well established, one of the challenges now is to determine which patients require a completion axillary dissection following a positive SLN biopsy.

METHODS

A prospective database of patients who underwent SLN biopsy for invasive breast cancer from July 1999 to November 2002 (n = 180) was analysed. Fifty four patients (30%) had one or more positive SLN, and all underwent a completion axillary dissection. This subgroup was further analysed to delineate which factors predicted non-SLN metastasis.

RESULTS

Twenty six of the 54 patients with a positive SLN had additional metastases in non-SLNs. Significant variables that predicted non-SLN metastasis included extranodal extension (odds ratio (OR), 17.399; 95% confidence interval (CI), 1.69 to 178.96) and macrometastasis within the SLN (OR, 6.985; 95% CI, 1.291 to 37.785).

CONCLUSIONS

In patients with invasive breast cancer and a positive SLN, extranodal extension or macrometastasis within the SLN were both independent predictors of non-SLN involvement.

Apolipoprotein A-1 interaction with plasma membrane lipid rafts controls cholesterol export from macrophages

Cholesterol efflux to apolipoprotein A-1 (apoA-1) from cholesterol-loaded macrophages is an important anti-atherosclerotic mechanism in reverse cholesterol transport. We recently provided kinetic evidence for two distinct pathways for cholesterol efflux to apoA-1 [Gaus et al. (2001) Biochemistry 40, 9363]. Cholesterol efflux from two membrane pools occurs sequentially with different kinetics; a small pool rapidly effluxed over the first hour, followed by progressive release from a major, slow efflux pool over several hours. In the present study, we propose that the rapid and slow cholesterol efflux pools represent cholesterol derived from lipid raft and nonraft domains of the plasma membrane, respectively. We provide direct evidence that apoA-1 binds to both lipid raft and nonraft domains of the macrophage plasma membrane. Conditions that selectively deplete plasma membrane lipid raft cholesterol, such as incorporation of 7-ketocholesterol or rapid exposure to cyclodextrins, block apoA-1 binding to these domains but also inhibit cholesterol efflux from the major, slow pool. We propose that cholesterol exported to apoA-1 from this major slow efflux pool derives from nonraft regions of the plasma membrane but that the interaction of apoA-1 with lipid rafts is necessary to stimulate this efflux.

Pathological axillary lymph nodes detected at mammographic screening

AIM

To investigate the significance of abnormal axillary lymph nodes detected at mammographic screening in the absence of a concomitant breast lesion.

METHODS

Twenty-three thousand, seven hundred and seven women were screened at the Merrion Unit as part of the Irish National Breast Screening Programme ("BreastCheck") in the period June 2000 to July 2002. Nine women (0.4 per 1000 women screened) were found to have an abnormal axillary lymph node(s) in the absence of a mammographic breast lesion and were recalled for assessment. The radiological criteria for recall included: size greater than or equal to 15 mm, round or irregular shape, increased node density and absence of hilar lucency. Each woman underwent further mammographic views, ultrasound examination of axilla and breast, clinical examination and lymph node biopsy either by 14G needle core biopsy (NCB) or open excision.

RESULTS

The final pathological diagnoses in the nine patients were oestrogen receptor (OR) positive metastatic breast carcinoma (two patients), metastatic malignant melanoma (one patient), malignant lymphoma (two patients), caseating granulomatous lymphadenitis suggestive of tuberculosis (one patient), and other benign conditions (three patients).

CONCLUSION

Abnormal axillary lymph nodes, in the absence of an accompanying breast lesion, are rarely identified on screening mammogram, but may harbour significant pathology and their presence on screening mammogram merits further investigation including biopsy.

Androgens up-regulate atherosclerosis-related genes in macrophages from males but not females: molecular insights into gender differences in atherosclerosis

OBJECTIVES

This study investigated the effects of androgens on gene expression in male- and female-donor macrophages.

BACKGROUND

Men have more severe coronary disease than women. Androgen exposure increases foam cell formation in male but not female macrophages, and male macrophages express >4-fold more androgen receptor messenger ribonucleic acid than female macrophages. Therefore, androgen exposure may have gender-specific and potentially pro-atherogenic effects in macrophages.

METHODS

Utilizing complementary deoxyribonucleic acid arrays, we studied the effects of a pure androgen (dihydrotestosterone, 40 nmol/l) on human monocyte-derived macrophages from healthy male and female donors (n = 4 hybridizations; 2 men, 2 women). Differential expression of atherosclerosis-related genes was confirmed by real-time reverse transcription-polymerase chain reaction (RT-PCR) in five male and five female donors. Functional corroboration of foam cell formation-related findings was undertaken by experiments using (125)I-acetylated low-density lipoprotein (AcLDL).

RESULTS

In male macrophages, androgen treatment produced differential up-regulation of 27 genes concentrated in five functional classes: 1) lipoprotein processing; 2) cell-surface adhesion; 3) extracellular signaling; 4) coagulation and fibrinolysis; and 5) transport protein genes. By contrast, none of 588 genes were up-regulated in female macrophages. By RT-PCR, we confirmed the gender-specific up-regulation of six of these atherosclerosis-related genes: acyl coenzyme A:cholesterol acyl transferase I, lysosomal acid lipase (LAL), caveolin-2, CD40, vascular endothelial growth factor-165 receptor, and tissue factor pathway inhibitor. Functionally, androgen-treated male macrophages showed increased rates of lysosomal AcLDL degradation, by 45% to 75% after 15 to 20 h of (125)I-AcLDL incubation (p = 0.001), consistent with increased LAL activity.

CONCLUSIONS

Androgens increase expression of atherosclerosis-related genes in male but not female macrophages, with functional consequences. These findings may contribute to the male predisposition to atherosclerosis.

Multiple Ets factors and interferon regulatory factor-4 modulate CD68 expression in a cell type-specific manner

CD68 is a transmembrane glycoprotein expressed in all cells of the mononuclear phagocyte lineage including monocytes and tissue resident macrophages. Deletion analysis of the 5'-flanking sequences of the gene demonstrated that the proximal -150-bp sequence of the CD68 promoter exhibits high level promoter activity in macrophages. Mutations that abolish Ets factor binding at positions -106 and -89 reduce promoter activity in macrophages to 12 and 30%, respectively. Band shift experiments show that PU.1 associates with the -89 site whereas, Elf-1 preferentially binds the -106 Ets binding site and enhances CD68 activity in vitro. Furthermore, chromatin immunoprecipitation experiments confirm that Elf-1 and PU.1 associate with the CD68 proximal promoter in vivo in THP-1 cells. PU.1 does not bind to the CD68 promoter alone but instead forms heterocomplexes with members of the interferon regulatory factor family (IRF) including IRF-4 and IRF-8. IRF-4 and IRF-8 typically mediate transcriptional activation when associated with PU.1 on composite elements. However, our data show that PU.1/IRF-4 and IRF-8 heterocomplexes down-regulate CD68 promoter activity in macrophages and repression is dependent on the integrity of both the IRF and PU.1 half-sites of this composite element. Chromatin immunoprecipitation data reveal that neither IRF-4 nor IRF-8 associate with the CD68 proximal promoter in macrophages in vivo but IRF-4 is associated with the promoter in B lymphocytes. We propose that expression of CD68 in myeloid cells requires the Ets transcription factors Elf-1 and PU.1 and CD68 expression is down-regulated in lymphoid cells by combinatorial interactions between PU.1 and IRF-4.

Thrombospondin 1 protein expression relates to good prognostic indices in ductal carcinoma in situ of the breast

AIM

Angiogenesis plays an important role in tumour growth and has been shown to occur around both in situ and invasive tumours. The degree of angiogenesis within tumours depends on the balance of pro-angiogenic and anti-angiogenic factors. One such anti-angiogenic factor is thrombospondin 1 (TSP-1). This study investigates the pattern of expression of TSP-1 in ductal carcinoma in situ (DCIS) of the breast and its relation to the surrounding microvessel pattern and density.

MATERIALS/METHODS

The expression of TSP-1 was studied in formalin fixed, paraffin wax embedded sections from 58 cases of pure DCIS, using a monoclonal antibody against TSP-1 and the avidin-biotin-diaminobenzidine immunoperoxidase detection system. Vessels were stained with a monoclonal antibody to the endothelial cell marker CD31. Stromal microvessel density was assessed by counting "hot spots" within 500 micro m of the basement membrane of involved ducts using a 25 point Chalkey graticule.

RESULTS

TSP-1 staining of the basement membrane around duct spaces with DCIS was seen in 69% of cases. In addition, staining of the stroma between involved duct spaces was seen in 31% of cases, with a fibrillary pattern identical to that seen in invasive breast carcinomas. In 12% of cases no staining for TSP-1 was seen. Two patterns of vascularity were identified. A cuff of vessels immediately adjacent to the basement membrane of ducts with DCIS was seen in 71% of cases. The presence of stromal TSP-1 was significantly associated with DCIS showing no/little necrosis (p = 0.01) and no/little periductal inflammation (p = 0.04). There was a trend between the presence of stromal TSP-1 and tumour cell negativity for p53 (p = 0.087). The stromal microvessel Chalkey point count ranged between 3.33 and 16. An increased stromal microvessel count was associated with high histological grade (p = 0.02), extensive necrosis (p = 0.047), and pronounced periductal inflammation (p = 0.049). There was no association between the presence of stromal TSP-1 and stromal microvessel density.

CONCLUSIONS

TSP-1 is expressed in the stroma around DCIS and in the immediately adjacent basement membrane. Expression of stromal TSP-1 is lost in DCIS with more aggressive histological features. The absence of a relation with microvessel density suggests that other angiogenic factors may play an important role in DCIS.

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

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

Linked chromosome 16q13 chemokines, macrophage-derived chemokine, fractalkine, and thymus- and activation-regulated chemokine, are expressed in human atherosclerotic lesions

Chemokines are important mediators of macrophage and T-cell recruitment in a number of inflammatory pathologies, and chemokines expressed in atherosclerotic lesions may play an important role in mononuclear cell recruitment and macrophage differentiation. We have analyzed the expression of the linked chromosome 16q13 genes that encode macrophage-derived chemokine (MDC/CCL22), thymus- and activation-regulated chemokine (TARC/CCL17), and the CX(3)C chemokine fractalkine (CX(3)CL1) in primary macrophages and human atherosclerotic lesions by reverse transcription-polymerase chain reaction and immunohistochemistry. We show that macrophage expression of the chemokines MDC, fractalkine, and TARC is upregulated by treatment with the Th2-type cytokines interleukin-4 and interleukin-13. High levels of MDC, TARC, and fractalkine mRNA expression are seen in some, but not all, human arteries with advanced atherosclerotic lesions. Immunohistochemistry shows that MDC, fractalkine, and TARC are expressed by a subset of macrophages within regions of plaques that contain plaque microvessels. We conclude that MDC, fractalkine, and TARC, which are chromosome 16q13 chemokines, could play a role in mononuclear cell recruitment into atherosclerotic lesions and influence the subsequent inflammatory response. Macrophage-expressed chemokines upregulated by interleukin-4 may be useful surrogate markers for the presence of Th2-type immune responses in human atherosclerotic lesions.

A human CD46 transgenic pig model system for the study of discordant xenotransplantation

BACKGROUND

The chronic shortage in the supply of human organs available for allotransplantation has turned attention toward the use of animals as potential donors, with pigs as the most likely species under consideration. Hyperacute rejection, the initial and immediate barrier to a pig-to-primate xenograft, has been addressed by generation of transgenic pigs that express the human membrane-bound complement-regulatory proteins CD59 and/or CD55. Difficulty has been encountered in generation of transgenic animals that express a third membrane-bound complement-regulatory protein, CD46.

METHODS

We have generated transgenic animals by using a large genomic construct that encompasses the entire human CD46 gene.

RESULTS

We report the first description of transgenic mice and pigs that express high levels of human CD46 in a cell and tissue type-specific manner, resembling patterns of endogenous CD46 expression observed in human tissues. Furthermore, when human CD46 transgenic porcine hearts were transplanted into baboons, the grafts did not succumb to hyperacute rejection, and survival extended for up to 23 days. Under the same conditions, nontransgenic grafts underwent hyperacute rejection within 90 min.

CONCLUSIONS

This is the first report to describe generation of transgenic pigs that express human CD46, and the first in vivo demonstration of the ability of human CD46 expressed on pig organs to regulate complement activation and overcome hyperacute rejection upon transplantation of a vascularized organ into nonhuman primates.

The human eukaryotic initiation factor 4AI gene (EIF4A1) contains multiple regulatory elements that direct high-level reporter gene expression in mammalian cell lines

The gene encoding human eukaryotic initiation factor 4A (EIF4A1) is located on chromosome 17p13, 667 bp upstream from the gene encoding the macrophage endosomal protein CD68. The EIF4AI gene contains 10 intervening sequences with the 1397-bp first intron containing a CpG-rich methylation-free island. Sequences capable of enhancing gene expression reside between positions -69 and -371 and positions -504 and -1100 of the EIF4AI 5' flanking sequence and within introns 1, 2, 3, 7, and 9. In macrophage cell lines, EIF4A1 expression vectors give sustained high-level reporter gene expression to levels 10 times higher than that obtained using the human cytomegalovirus immediate-early gene promoter/enhancer. Sequences of the human EIF4AI gene may find application in the development of new vectors for gene therapy and genetic vaccination.

Loss of bcl-2 expression in ductal carcinoma in situ of the breast relates to poor histological differentiation and to expression of p53 and c-erbB-2 proteins

AIM

This study (1) investigates the incidence of bcl-2 protein expression in a series of 108 cases of ductal carcinoma in situ (DCIS), including 25 with early invasive carcinoma, and (2) evaluates the relationship of bcl-2 expression to the histological grade of DCIS and to the expression of oestrogen receptor (ER), c-erbB-2 and p53 proteins.

METHODS AND RESULTS

The expression of bcl-2, oestrogen receptor (ER), c-erbB-2 and p53 proteins was determined immunohistochemically. Cases were regarded as positive for individual antibodies when at least 10% of the DCIS cells showed positive staining. DCIS was graded histologically as well (n = 9), intermediately (n = 24), or poorly differentiated (n = 75). bcl-2 expression was documented in 57 cases (53%) and was strongly associated with the histological grade of DCIS (P < 0.0001). All cases of well-differentiated DCIS were bcl-2 positive and loss of bcl-2 expression was almost exclusively confined to poorly differentiated DCIS lesions. bcl-2 expression was also closely associated with positive ER status (P < 0.0001). Forty-seven of 57 (82%) bcl-2 positive cases were ER positive while 49/51 (96%) bcl-2 negative cases were ER negative. There was a significant inverse correlation between bcl-2 expression and both p53 protein expression (P = 0.0004) and c-erbB-2 expression (P < 0.0001). Nineteen of 24 (79%) p53 positive cases and 38/45 (84%) c-erbB-2 positive cases showed loss of bcl-2.

CONCLUSIONS

Loss of bcl-2 expression occurs in poorly differentiated DCIS and is related to negative ER status and to positive p53 and c-erbB-2 status. This pattern of bcl-2 expression and its association with other biological markers in DCIS is similar to that reported in invasive breast carcinoma.