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Background Type-17 inflammation characterizes psoriasis, a chronic skin disease. Because several inflammatory cytokines contribute to psoriasis pathogenesis, inhibiting the simultaneous production of these cytokines in TH17 cells may be beneficial in psoriasis. We found that Cav1.4, encoded by CACNA1F, was the only Cav1 calcium channel expressed in TH17 cells. Objective We sought to investigate the role of Cav1.4 expression in early TH17-activation events and effector functions, as well as its association with TH17 signature genes in lesional psoriatic (LP) skins. Methods Transcriptional gene signatures associated with CACNA1F expression were examined in LP skins by RT-PCR and in situ hybridization. Cav1 inhibitor and/or shRNA lentivectors were used to assess the contribution of Cav1.4 in TH17 activation and effector functions in a 3-dimensional skin reconstruction model. Results CACNA1F expression correlated with inflammatory cytokine expression that characterizes LP skins and was preferentially associated with RORC expression in CD4+ and CD4− cells from LP biopsies. Nicardipine, a Cav1 channel antagonist, markedly reduced inflammatory cytokine production by TH17 cells from blood or LP skin. This was associated with decreased TCR-induced early calcium events at cell membrane and proximal signaling events. The knockdown of Cav1.4 in TH17 cells impaired cytokine production. Finally, Cav1 inhibition reduced the expression of the keratinocyte genes characteristic of TH17-mediated psoriasis inflammation in human skin equivalents. Conclusions Cav1.4 channels promote TH17-cell functions both at the periphery and in inflammatory psoriatic skin.

PDF file - 135K, Expression of PLK2, PLK3 and PLK4 in human breast cancers

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Type-17 inflammation characterizes psoriasis, a chronic skin disease. Because several inflammatory cytokines contribute to psoriasis pathogenesis, inhibiting the simultaneous production of these cytokines in TWe sought to investigate the role of CaTranscriptional gene signatures associated with CACNA1F expression were examined in LP skins by RT-PCR and in situ hybridization. CaCACNA1F expression correlated with inflammatory cytokine expression that characterizes LP skins and was preferentially associated with RORC expression in CD4Ca

International audience; Skin aging is a complex biological process mixing intrinsic and extrinsic factors, such as sun exposure. At the molecular level, skin aging affects in particular the extracellular matrix proteins. Materials and Methods: Using Raman imaging, which is a nondestructive approach appropriate for studying biological samples, we analyzed how aging modifies the matrix proteins of the papillary and reticular dermis. Biopsies from the buttock and dorsal forearm of volunteers younger than 30 and older than 60 were analyzed in order to identify chronological and photoaging processes. Analyses were performed on skin section, and Raman spectra were acquired separately on the different dermal layers. Results: We observed differences in dermal matrix structure and hydration state with skin aging. Chronological aging alters in particular the collagen of the papillary dermis, while photoaging causes a decrease in collagen stability by altering proline and hydroxyproline residues in the reticular dermis. Moreover, chronological aging alters glycosaminoglycan content in both dermal compartments. Conclusion: Alterations of the papillary and reticular dermal matrix structures during photo-and chronological aging were clearly depicted by Raman spectroscopy.

The formation of DNA photoproducts caused by solar UVR exposure needs to be investigated in-vivo and in particular in order to assess sunscreens' level of protection against solar genotoxicity. The study's purposes were: i) to evaluate if the roof of suction blisters is an appropriate sampling method for measuring photoproducts, and ii) to measure in-vivo sunscreen protection against cyclobutane pyrimidine dimers. Skin areas on the interior forearms of eight healthy volunteers were exposed in-vivo to 2 MED of simulated solar radiation (SSR) and to 15 MED on a sunscreen protected area. After irradiation, six suction blisters were induced and the blister roofs were collected. Analysis of SSR-induced CPDs was performed by two independent methods: a chromatography coupled to mass spectroscopy (HPLC-MS/MS) approach and a 3D-imaging of CPD immunostaining by multiphoton microscopy on floating epidermal sheets. HPLC-MS/MS analyses showed that SSR-unexposed skin presented no CPD dimers, whereas 2 MED SSR-exposed skin showed a significant number of TT-CPD. The sunscreen covered skin exposed to 15 MED appeared highly protected from DNA damage, as the amount of CPD-dimers remained below the detection limit. The multiphoton-immunostaining analysis consistently showed that no CPD staining was observed on the non-SSR-exposed skin. A significant increase of CPD staining intensity and number of CPD-positive cells were observed on the 2 MED SSR-exposed skin. Sunscreen protected skin presented a very low staining intensity and the number of CPD-positive cells remained very close to non-SSR-exposed skin. This study showed that suction blister samples are very appropriate for measuring CPD dimers in-vivo, and that sunscreens provide high protection against UVR-induced DNA damage.

Atopic dermatitis (AD) is a chronic and multifactorial inflammatory skin disease involving various dendritic cells such as epidermal Langerhans cells (LC) and inflammatory dendritic epidermal cells (IDECs). Most of the clinical studies was performed on isolated cells, and thus, it would be useful to characterize directly on the human epidermal tissue the first cellular events occurred during the AD. The suction blister method was used to obtain whole epidermis samples and interstitial cutaneous fluids. Employing multiphoton microscopy, we analyzed the early dynamic behavior of inflammatory cells using Dermatophagoides pteronyssinus atopy patch test (Derp-APT) and evaluated the effects of emollient pre-application. Derp-APT application provoked rapid and strong infiltration of IDECs, and proliferation and activation of LC in the AD subjects' epidermis. Moreover, emollient pre-application strengthened the defective skin barrier and had positive effects on inflammatory cells' behavior, characterized by the complete inhibition of IDEC influx and the presence of immature LC.

Background: To identify ER+ve ERBB2-ve ductal T1T2N0 carcinomas associated with a poor prognosis remains challenging. We have previously demonstrated that the number of chromosomal breakpoints assessed by CGH could be a marker of worse outcome for breast carcinomas. Our aim was to validate the CGH based signature in a series of luminal ductal and T1T2 N0 carcinoma patients with long-term clinical follow-up. Patients and methods: We analyzed 214 patients treated for an invasive ductal ER+ve ERBB2-ve carcinomas, smaller than 30mm. The training set was composed of 109 patients (10.9 years of median follow-up; 30 cases associated with a metastatic event within less than 4 years/79 control cases with no metastastic event at 5 years) and the validation set of 105 patients (10.5 years of median follow-up; 30 relapses including contra-lateral breast carcinomas, loco-regional relapses and 8 metastatic events). None of the patient received adjuvant chemotherapy. 16 received an adjuvant hormonotherapy (10 in the training and 6 in the validation groups). We genotyped the sample set with the SNP6.0 affymetrix array. After RMA normalisation using Genotyping console, segmentation was performed according to the Zhang and Siegmund maximum method. In the training data set, the number of breakpoints was assessed, linked to outcome and the threshold optimising the sensitivity and specificity was determined (ROC curve). The threshold prognostic value was then tested on the validation series (Kaplan Meier analysis, log rank test, determination of relative risk and its confidence interval with a Cox model). Results: In the training set, median numbers of breakpoints were 7 in cases that experienced a metastatic event after more than 5 years and 40.5 in cases that experienced a metastatic event in less than 4 years. The threshold (Younden index ) was 34 breakpoints with a sensitivity of 0.57 and a specificity of 0.94 (AUC: 0.81[0.71;0.91]). In the validation set, the outcome of patients with more than 34 breakpoints was poorer than that of patients with less than 34 breakpoints (34 breakpoints: 11 events out of 22 patients with a median time to progression of 108 months; p34 versus 34 breakpoints: 4 events out of 22 patients with a median time to progression of 108 months; p=0.009 (logrank test); RR: 5.29 [1.32; 21.26]). Conclusion: We demonstated that patients with T1T2 ( Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P4-09-01.

Predicting evolution of small node-negative breast carcinoma is a real challenge in clinical practice. The aim of this study was to search whether qualitative or quantitative DNA changes may help to predict metastasis of small node-negative breast carcinoma. Small invasive ductal carcinomas without axillary lymph node involvement (T1T2N0) from 168 patients with either good (111 patients with no event at 5 years after diagnosis) or poor (57 patients with early metastasis) outcome were analyzed with comparative genomic hybridization (CGH) array. A CGH classifier, identifying low- and high-risk groups of metastatic recurrence, was established in a training set of 78 patients, then validated, and compared with clinicopathological parameters in a distinct set of 90 patients. The genomic status of regions located on 2p22.2, 3p23, and 8q21-24 and the number of segmental alterations were defined in the training set to classify tumors into low- or high-risk groups. In the validation set, in addition to estrogen receptors and grade, this CGH classifier provided significant prognostic information in multivariate analysis (odds ratio, 3.34; 95% confidence interval 1.01-11.02; P = 4.78 × 10(-2), Wald test). This study shows that tumor DNA contains important prognostic information that may help to predict metastasis in T1T2N0 tumors of the breast.

Transcriptomic analyses identified four major groups among invasive ductal carcinomas, associated with different clinical outcomes. Their definitions in practice is still matter of debate. Our aims were 1) to validate definitions based on immunohistochemical markers and grade: luminal A= ER and or PR+ve, grade I HER2−ve, luminal B= ER+ve and/or PR+ve, HER2+ve or grade III, HER2 enriched carcinomas= HER2+ve and ER-ve, basal-like/triple negative carcinomas= grade III, ER-ve, PR-ve, HER2−ve and expression of at least one of the basal-like markers (CK5/6, CK14, EGFR); 2) to refine this immunohistochemical definition. 142 consecutive tumors were selected in our tumour bank (42 triple-negative and grade III; 31 HER2+ve and ER-ve; 35 luminal B ER or PR+ve and grade III (7 cases) or HER2+ve (28 cases); luminal A (34 ER+ve or PR+ve, grade I)). Transcriptomic analyses were performed using Affymetrix U133+2 arrays (good quality RNAs obtained for all frozen specimens). The molecular classes determined according to proposed definitions were compared to those obtained with unsupervised clustering analyses using datas after GC-RMA normalisation (with the intrinsic gene list genes and with the highest variance genes). Marker patterns of expression (CK 8/18, 5/6, 14, EGFR, BCL2 and Ki67) were analysed within each molecular class. Based on the phenotypical definition and grade, 10 and 9% of cases were misclassified respectively using unsupervised clustering either with the intrinsic gene list or the highest variance genes. The misclassified tumors were luminal B HER2+ve case with low ER level of expression, or HER2+ve and ER-ve cases classified among the triple-negative group. 39 out of 42 (93%) triple negative expressed at least one of the basal markers. RP expression pattern differed between luminal A and B carcinomas. All luminal A showed at least > 15% of positive cells and 65% of them harboured > 50% of positive cells. In contrast, luminal B showed < 15% of positive cells in 70% of the cases. Bcl2 was negative in 40% of the luminal B cases and positive (> 20% stained cells) in more than 90% of the luminal A cases. CK14 was positive (i.e. > 1% positive cell) in 65% of the triple negative cases, compared to CK5/6 positive in 58% of the cases. Ki67 was > 20% in 90% of the triple negative and in 55% of luminal B cases compared to less than 5% of the luminal A cases. 20 and 30% of HER2+ve ER-ve carcinomas expressed CK5/6, CK14 and EGFR associated in more than 90% of the cases to CK8/18 positivity (> 20% positive cells). Identification of molecular classes of breast carcinomas was accurately determined by immunohistochemistry and grade. Low level of RP expression and BCL2 negativity were part of the luminal B phenotype. CK14 was more sensitive in this population of triple negative carcinomas to identify basal-like carcinomas. KI67 was highly expressed in the vast majority if not all breast triple negative carcinomas. HER2+ve ER-ve carcinomas can express basal markers but in contrast to basal-like carcinomas, associated in the large majority of the cases to CK8/18 expression. The accurate determination of molecular groups of breast carcinomas should be a key parameter for development of targeted therapies within each group. Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P3-05-03.

Purpose(1) To determine TweakR expression in human breast cancers (BC), (2) evaluate the antitumor effect of the anti-TweakR antibody PDL192, used alone or after chemotherapy-induced complete remission (CR), on patient-derived BC xenografts (PDX) and (3) define predictive markers of response.Experimental designTweakR expression was analyzed by IHC on patients and PDXs BC samples. In vivo antitumor effect of PDL192 was evaluated on eight TweakR-positive BC PDXs alone or after complete remission induced by a combination of doxorubicin and cyclophosphamide. Using both responding and resistant PDX tumors after PDL192 administration, RT-QPCR were performed on a wide list of selected candidate genes to identify predictive markers of response.ResultsTweakR protein was expressed in about half of human BC samples. In vivo PDL192 treatment had significantly anti-tumor activity in 4 of 8 TweakR-positive BC PDXs, but no correlation between the expression level of the Tweak receptor and response to therapy was observed. PDL192 also significantly delayed tumor relapse after CR. Finally, an 8 gene signature was defined from sensitive and resistant PDXs.ConclusionsPDL192 was highly efficient in some BC PDXs. We found 8 genes that were differentially expressed in responding and resistant tumors and could constitute a gene expression signature which would need to be extended to other xenograft models for confirmation. These data confirm the therapeutic potential of TweakR targeting in BC and the possibility of prospectively selecting patients who might benefit from therapy.

Triple-negative breast cancer (TNBC) represents a subgroup of breast cancers (BC) associated with the most aggressive clinical behavior. No targeted therapy is currently available for the treatment of patients with TNBC. In order to discover potential therapeutic targets, we searched for protein kinases that are overexpressed in human TNBC biopsies and whose silencing in TNBC cell lines causes cell death. A cohort including human BC biopsies obtained at Institut Curie as well as normal tissues has been analyzed at a gene-expression level. The data revealed that the human protein kinase monopolar spindle 1 (hMPS1), also known as TTK and involved in mitotic checkpoint, is specifically overexpressed in TNBC, compared to the other BC subgroups and healthy tissues. We confirmed by immunohistochemistry and reverse phase protein array that TNBC expressed higher levels of TTK protein compared to the other BC subgroups. We then determined the biological effects of TTK depletion by RNA interference, through analyses of tumorigenic capacity and cell viability in different human TNBC cell lines. We found that RNAi-mediated depletion of TTK in various TNBC cell lines severely compromised their viability and their ability to form colonies in an anchorage-independent manner. Moreover, we observed that TTK silencing led to an increase in H2AX phosphorylation, activation of caspases 3/7, sub-G1 cell population accumulation and high annexin V staining, as well as to a decrease in G1 phase cell population and an increased aneuploidy. Altogether, these data indicate that TTK depletion in TNBC cells induces apoptosis. These results point out TTK as a protein kinase overexpressed in TNBC that may represent an attractive therapeutic target specifically for this poor prognosis associated subgroup of breast cancer.

Breast cancers are composed of molecularly distinct subtypes with different clinical outcomes and responses to therapy. To discover potential therapeutic targets for the poor prognosis-associated triple-negative breast cancer (TNBC), gene expression profiling was carried out on a cohort of 130 breast cancer samples. Polo-like kinase 1 (PLK1) was found to be significantly overexpressed in TNBC compared with the other breast cancer subtypes. High PLK1 expression was confirmed by reverse phase protein and tissue microarrays. In triple-negative cell lines, RNAi-mediated PLK1 depletion or inhibition of PLK1 activity with a small molecule (BI-2536) induced an increase in phosphorylated H2AX, G2–M arrest, and apoptosis. A soft-agar colony assay showed that PLK1 silencing impaired clonogenic potential of TNBC cell lines. When cells were grown in extracellular matrix gels (Matrigel), and exposed to BI-2536, apoptosis was observed specifically in TNBC cancerous cells, and not in a normal cell line. When administrated as a single agent, the PLK1 inhibitor significantly impaired tumor growth in vivo in two xenografts models established from biopsies of patients with TNBC. Most importantly, the administration of BI-2536, in combination with doxorubicin + cyclophosphamide chemotherapy, led to a faster complete response compared with the chemotherapy treatment alone and prevented relapse, which is the major risk associated with TNBC. Altogether, our observations suggest PLK1 inhibition as an attractive therapeutic approach, in association with conventional chemotherapy, for the management of patients with TNBC. Cancer Res; 73(2); 813–23. ©2012 AACR.

Background: The accurate prognosis definition to tailor treatment for early luminal invasive breast carcinoma patients remains challenging. Materials and Methods: Two hundred fourteen early luminal breast carcinomas were genotyped with single nucleotide polymorphisms (SNPs) array to determine the number of chromosomal breakpoints as a marker of genomic instability. Proliferation was assessed by KI67 (immunohistochemistry) and genomic grade index (transcriptomic analysis). IHC3 (IHC4 score for HER2 negative tumors) was also determined. Results: In the training set (109 cases), the optimal cut-off was 34 breakpoints with a specificity of 0.94 and a sensitivity of 0.57 (Area under the curve (AUC): 0.81[0.71; 0.91]). In the validation set (105 cases), the outcome of patients with > 34 breakpoints (11 events / 22 patients) was poorer (logrank test p < 0.001; Relative Risk (RR): 3.7 [1.73; 7.92]), than that of patients with < 34 breakpoints (19 events / 83 patients). Whereas genomic grade and KI67 had a significant prognostic value in univariate analysis in contrast to IHC3 that failed to have a statistical significant prognostic value in this series, the number of breakpoints remained the only significant parameter predictive of outcome (RR: 3.47, Confidence Interval (CI [1.29; 9.31], p = 0.014)) in multivariate analysis. Conclusion: Genomic instability, defined herein as a high number of chromosomal breakpoints, in early stage luminal breast carcinoma is a stronger prognostic marker than proliferation.

Background The increasing number of methodologies and tools currently available to analyse gene expression microarray data can be confusing for non specialist users. Findings Based on the experience of biostatisticians of Institut Curie, we propose both a clear analysis strategy and a selection of tools to investigate microarray gene expression data. The most usual and relevant existing R functions were discussed, validated and gathered in an easy-to-use R package (EMA) devoted to gene expression microarray analysis. These functions were improved for ease of use, enhanced visualisation and better interpretation of results. Conclusions Strategy and tools proposed in the EMA R package could provide a useful starting point for many microarrays users. EMA is part of Comprehensive R Archive Network and is freely available at http://bioinfo.curie.fr/projects/ema/.

Almost all prostate cancers respond to androgen deprivation treatment but many recur. We postulated that risk of hormone escape--frequency and delay--are influenced by hormone therapy modalities. More, hormone therapies induce crucial biological changes involving androgen receptors; some might be targets for escape prevention. We investigated the relationship between the androgen deprivation treatment and the risk of recurrence using nude mice bearing the high grade, hormone-dependent human prostate cancer xenograft PAC120. Tumor-bearing mice were treated by Luteinizing-Hormone Releasing Hormone (LHRH) antagonist alone, continuous or intermittent regimen, or combined with androgen receptor (AR) antagonists (bicalutamide or flutamide). Tumor growth was monitored. Biological changes were studied as for genomic alterations, AR mutations and protein expression in a large series of recurrent tumors according to hormone therapy modalities. Therapies targeting Her-2 or AKT were tested in combination with castration. All statistical tests were two-sided. Tumor growth was inhibited by continuous administration of the LH-RH antagonist degarelix (castration), but 40% of tumors recurred. Intermittent castration or complete blockade induced by degarelix and antiandrogens combination, inhibited tumor growth but increased the risk of recurrence (RR) as compared to continuous castration (RR(intermittent): 14.5, RR(complete blockade): 6.5 and 1.35). All recurrent tumors displayed new quantitative genetic alterations and AR mutations, whatever the treatment modalities. AR amplification was found after complete blockade. Increased expression of Her-2/neu with frequent ERK/AKT activation was detected in all variants. Combination of castration with a Her-2/neu inhibitor decreased recurrence risk (0.17) and combination with an mTOR inhibitor prevented it. Anti-hormone treatments influence risk of recurrence although tumor growth inhibition was initially similar. Recurrent tumors displayed genetic instability, AR mutations, and alterations of phosphorylation pathways. We postulated that Her-2/AKT pathways allowed salvage of tumor cells under castration and we demonstrated that their inhibition prevented tumor recurrence in our model.

Background: PDL192 is a humanized IgG1 monoclonal antibody that binds the human TWEAK receptor (TweakR). TweakR, a member of the TNFR (Tumor Necrosis Factor Receptor) superfamily, is overexpressed in several human cancers including breast cancer (BC). In BC, it may also play a role in the invasive and metastatic potential of the disease (Willis et al, Mol Cancer Res 2008). In TweakR-expressing cancer cell lines or mouse xenograft models, PDL192 has a potent antitumor effect (Culp et al., CCR 2010). All these data therefore suggest that anti-TweakR targeting could be a promising new therapeutic approach for human BC patients. Material and methods: TweakR expression was assessed by IHC (immunohistochemistry) on 3 Tissue-Micro-Array (TMA) banks of BC samples (basal-like, ERBB2, and luminal A/B), and 25 primary human BC xenografts (HBCx). The cut-off of positivity was defined as at least 25% cells with membraneous or cytoplasmic staining or by a combined score of percentage of positive staining cells x intensity > 50. The in vivo antitumor effect of PDL192 was then assessed on 7 TweakR-positive models (10 mg/kg thrice a week for 3 weeks by intraperitoneal route) in which one in combination with chemotherapy as maintenance therapy, as previsouly reported (Marangoni et al., BJC 2009). Results: TMA analyses showed that TweakR was expressed in 16/37 basal like BC (43%), 23/37 ERBB2-positive BC (62%), and 38/71 luminal BC (54%). A high TweakR expression was correlated with double estrogen receptor- and Her2-positive tumors. Moreover, 13/25 xenografts have been found to be TweakR-positive (52%). Nine human BC models have been treated with PDL192, with 4 models (44%) showing a tumor growth inhibition (TGI) ranging between 59% and 91%. No correlation has been observed between TweakR expression and in vivo TGI. Moreover, when PDL192 was administered in complete remission after chemotherapy (doxorubicin + cyclophosphamide), we observed a highly significant delay of relapse greater than 2 months. Conclusions: TweakR is expressed in 77/145 human BC samples (53%). In in vivo experiments, PDL192 showed potent TGI in 4/9 models, and significantly delayed tumor relapses after chemotherapy-induced complete remission. All these data therefore support the use of anti-TWEAK receptor monoclonal antibodies in the treatment of TweakR-positive BC patients. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 1772. doi:10.1158/1538-7445.AM2011-1772

Abstract #1081 Background: The purpose of this study was to identify a genomic signature of early metastatic recurrence, in order to predict accurately breast carcinomas clinical outcome and to select patients with node negative and small tumor size ( Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 1081.

International audience; Introduction Basal-like carcinomas (BLCs) and human epidermal growth factor receptor 2 overexpressing (HER2+) carcinomas are the subgroups of breast cancers that have the most aggressive clinical behaviour. In contrast to HER2+ carcinomas, no targeted therapy is currently available for the treatment of patients with BLCs. In order to discover potential therapeutic targets, we aimed to discover deregulated signalling pathways in human BLCs. Methods In this study, we focused on the oncogenic phosphatidylinositol 3-kinase (PI3K) pathway in 13 BLCs, and compared it with a control series of 11 hormonal receptor negative- and grade III-matched HER2+ carcinomas. The two tumour populations were first characterised by immunohistochemistry and gene expression. The PI3K pathway was then investigated by gene copy-number analysis, gene expression profiling and at a proteomic level using reverse-phase protein array technology and tissue microarray. The effects of the PI3K inhibition pathway on proliferation and apoptosis was further analysed in three human basal-like cell lines. Results The PI3K pathway was found to be activated in BLCs and up-regulated compared with HER2+ tumours as shown by a significantly increased activation of the downstream targets Akt and mTOR (mammalian target of rapamycin). BLCs expressed significantly lower levels of the tumour suppressor PTEN and PTEN levels were significantly negatively correlated with Akt activity within that population. PTEN protein expression correlated significantly with PTEN DNA copy number and more importantly, reduced PTEN DNA copy numbers were observed specifically in BLCs. Similar to human samples, basal-like cell lines exhibited an activation of PI3K/Akt pathway and low/lack PTEN expression. Both PI3K and mTOR inhibitors led to basal-like cell growth arrest. However, apoptosis was specifically observed after PI3K inhibition. Conclusions These data provide insight into the molecular pathogenesis of BLCs and implicate the PTEN-dependent activated Akt signalling pathway as a potential therapeutic target for the management of patients with poor prognosis BLCs.

International audience; Malignant effusion in invasive breast carcinoma is associated with poor prognosis. To decipher molecular events leading to metastasis and to identify reliable markers for targeted therapies are of crucial need. Therefore, we have used cDNA microarrays to delineate molecular signatures associated with metastasis and relapse in breast carcinoma effusions. Taking advantage of an immunomagnetic method, we have purified to homogeneity EpCAM-positive cells from 34 malignant effusions. Immunopurified cells represented as much as 10% of the whole cell fraction and their epithelial and carcinoma features were confirmed by immunofluorescence labeling. Gene expression profiles of 19 immunopurified effusion samples, were analyzed using human pan-genomic microarrays, and compared with those of 4 corresponding primary tumors, 8 breast carcinoma effusion-derived cell lines, and 4 healthy mammary tissues. Principal component and multiple clustering analyses of microarray data, clearly identified distinctive molecular portraits corresponding to the 4 categories of specimens. Of uppermost interest, effusion samples were arranged in 2 subsets on the basis of their gene expression patterns. The first subset partly shares a gene expression signature with the different cell lines, and overexpresses CD24, CD44 and epithelial cytokeratins 8,18,19. The second subset overexpresses markers related to aggressive invasive carcinoma (uPA receptor, S100A4, vimentin, CXCR4). These findings demonstrate the importance of using pure cell fractions to accurately decipher in silico gene expression of clinical specimens. Further studies will lead to the identification of genes of oustanding importance to diagnose malignant effusion, predict survival and tailor appropriate therapies to the metastatic effusion disease in breast carcinoma patients.