Distinct Molecular Signature of Inflammatory Breast Cancer by cDNA Microarray Analysis

Hyperactivated NF-{kappa}B and AP-1 transcription factors promote highly accessible chromatin and constitutive transcription across the interleukin-6 gene promoter in metastatic breast cancer cells

Interleukin-6 (IL-6), involved in cancer-related inflammation, acts as an autocrine and paracrine growth factor, which promotes angiogenesis, metastasis, and subversion of immunity, and changes the response to hormones and to chemotherapeutics. We explored transcription mechanisms involved in differential IL-6 gene expression in breast cancer cells with different metastatic properties. In weakly metastatic MCF7 cells, histone H3 K9 methylation, HP1 binding, and weak recruitment of AP-1 Fra-1/c-Jun, NF-kappaB p65 transcription factors, and coactivators is indicative of low chromatin accessibility and gene transcription at the IL-6 gene promoter. In highly metastatic MDA-MB231 cells, strong DNase, MNase, and restriction enzyme accessibility, as well potent constitutive transcription of the IL-6 gene promoter, coincide with increased H3 S10 K14 phosphoacetylation and promoter enrichment of AP-1 Fra-1/c-Jun and NF-kappaB p65 transcription factors and MSK1, CBP/p300, Brg1, and Ezh2 cofactors. Complementation, silencing, and kinase inhibitor experiments further demonstrate involvement of AP-1 Fra-1/c-Jun and NF-kappaB p65/RelB members, but not of the alpha estrogen receptor in promoting chromatin accessibility and transcription across the IL-6 gene promoter in metastatic breast cancer cells. Finally, the natural withanolide Withaferin A was found to repress IL-6 gene transcription in metastatic breast cancer cells upon dual inhibition of NF-kappaB and AP-1 Fra-1 transcription factors and silencing of IL-6 promoter chromatin accessibility.

Molecular targets for treatment of inflammatory breast cancer

Despite progress in combined-modality treatment with chemotherapy, surgery, and radiation therapy, the long-term outcome for patients with inflammatory breast cancer (IBC) remains poor. Therapies that target vasculolymphatic processes--angiogenesis, lymphangiogenesis, and vasculogenesis--have shown potential in the treatment for IBC, as represented by bevacizumab. Although the therapeutic effect of targeting lymphangiogenesis and vasculogenesis requires further investigation, targeting of angiogenesis has potential, not only through true antiangiogenic effects, but also through antitumor effects in concert with other pathways. Therapies that target cell proliferation pathways are the most promising targeted therapies for IBC. In particular, therapies that target human epidermal growth factor receptor 2 (for example, trastuzumab and lapatinib) have performed well in the clinical setting, leading to improved outcomes for patients with IBC. Metastatic pathways could have a unique, key role in the aggressiveness of the IBC phenotype. Further extensive work on the unique molecular characteristics of IBC is essential to ensure improved outcomes for patients with this disease. In this Review we discuss three pathways--vasculolymphatic, cell proliferation and metastatic--that could represent important targets in the treatment of IBC.

cDNA microarray analysis of inflammatory breast cancer signatures

Global gene expression profiling studies conducted over the last couple of years have shown that molecular profiling of breast cancers can be used to identify clinically and genetically significant subtypes of breast carcinomas and subgroups of patients with different prognosis or disease outcome, and to predict therapeutic response to both endocrine and chemotherapeutic drugs. We studied one particularly aggressive form of locally advanced breast cancer, namely inflammatory breast cancer (IBC) using cDNA micro-arrays. We demonstrated that IBC is characterized by a different gene expression profile, not related to any of the previously identified breast cancer subtypes. This gene expression profile revealed potential therapeutic targets, such as the transcription factor NF-kappaB. Gene expression analysis using cDNA microarrays is a technique to simultaneously analyze the expression of thousands of genes. cDNA fragments of these genes are present in spots at the surface of a glass slide. These cDNA fragments will bind to fluorescently labeled RNA molecules during hybridization. Hence, the spot containing the hybridized RNA molecules will produce a fluorescent signal proportional to the amount of RNA molecules present in sample. This fluorescent signal is a measure for gene expression. Using cDNA microarrays, complex patterns of gene expression can be deciphered.

Relapse-free survival in breast cancer patients is associated with a gene expression signature characteristic for inflammatory breast cancer

PURPOSE

We hypothesize that a gene expression profile characteristic for inflammatory breast cancer (IBC), an aggressive form of breast cancer associated with rapid cancer dissemination and poor survival, might be related to tumor aggressiveness in non-IBC (nIBC).

EXPERIMENTAL DESIGN

RNA from 17 IBC samples and 40 nIBC samples was hybridized onto Affymetrix chips. A gene signature predictive of IBC was identified and applied onto 1,157 nIBC samples with survival data of 881 nIBC samples. Samples were classified as IBC-like or nIBC-like. The IBC signature classification was compared with the classifications according to other prognostically relevant gene signatures and clinicopathologic variables. In addition, relapse-free survival (RFS) was compared by the Kaplan-Meyer method.

RESULTS

Classification according to the IBC signature is significantly (P < 0.05) associated with the cell-of-origin subtypes, the wound healing response, the invasive gene signature, the genomic grade index, the fibroblastic neoplasm signature, and the 70-gene prognostic signature. Significant associations (P < 0.01) were found between the IBC signature and tumor grade, estrogen receptor status, ErbB2 status, and patient age at diagnosis. Patients with an IBC-like phenotype show a significantly shorter RFS interval (P < 0.05). Oncomine analysis identified cell motility as an important concept linked with the IBC signature.

CONCLUSIONS

We show that nIBC carcinomas having an IBC-like phenotype have a reduced RFS interval. This suggests that IBC and nIBC show comparable phenotypic traits, for example augmented cell motility, with respect to aggressive tumor cell behavior. This observation lends credit to the use of IBC to study aggressive tumor cell behavior.

Human monocytes augment invasiveness and proteolytic activity of inflammatory breast cancer

Inflammatory breast cancer (IBC) is the most aggressive form of breast cancer, and here, we examined in vitro the interactions between the human IBC cell line SUM149 and U937 human naive monocytes. We found an altered morphology, enhanced invasiveness and proteolytic activity of SUM149 cells when cultured with U937 cells or in U937-conditioned media (U937-CM). Increases in expression and activity of the cysteine protease cathepsin B and expression of caveolin-1 were also detected in SUM149 cells grown in U937-CM, thus suggesting a contribution of these proteins to the augmented invasion through and proteolysis of the extracellular matrix by the IBC cells.

Aberrant methylation of the Adenomatous Polyposis Coli (APC) gene promoter is associated with the inflammatory breast cancer phenotype

Aberrant methylation of the adenomatous polyposis coli (APC) gene promoter occurs in about 40% of breast tumours and has been correlated with reduced APC protein levels. To what extent epigenetic alterations of the APC gene may differ according to specific breast cancer phenotypes, remains to be elucidated. Our aim was to explore the role of APC methylation in the inflammatory breast cancer (IBC) phenotype. The status of APC gene promoter hypermethylation was investigated in DNA from normal breast tissues, IBC and non-IBC by both conventional and real-time quantitative methylation-specific PCR (MSP). APC methylation levels were compared with APC mRNA and protein levels. Hypermethylation of the APC gene promoter was present in 71% of IBC samples (n=21) and 43% of non-IBC samples (n=30) by conventional MSP (P=0.047). The APC gene also showed an increased frequency of high methylation levels in IBC (in 74% of cases, n=19) vs non-IBC (in 46% of cases, n=35) using a qMSP assay (P=0.048). We observed no significant association between APC methylation levels by qMSP and APC mRNA or protein expression levels. In conclusion, for the first time, we report the association of aberrant methylation of the APC gene promoter with the IBC phenotype, which might be of biological and clinical importance.

Gene expression profiling of breast cancer

DNA microarray platforms for gene expression profiling were invented relatively recently, and breast cancer has been among the earliest and most intensely studied diseases using this technology. The molecular signatures so identified help reveal the biologic spectrum of breast cancers, provide diagnostic tools as well as prognostic and predictive gene signatures, and may identify new therapeutic targets. Data are best presented in an open access format to facilitate external validation, the most crucial step in identifying robust, reproducible gene signatures suitable for clinical translation. Clinically practical applications derived from full expression profile studies already in use include reduced versions of microarrays representing key discriminatory genes and therapeutic targets, quantitative polymerase chain reaction assays, or immunohistochemical surrogate panels (suitable for application to standard pathology blocks). Prospective trials are now underway to determine the value of such tools for clinical decision making in breast cancer; these efforts may serve as a model for using such approaches in other tumor types.

Defining the molecular biology of inflammatory breast cancer

Inflammatory breast cancer (IBC) is a rare, but aggressive form of breast cancer. Despite the progress related to the introduction of primary combination chemotherapy (CT) to the multimodality treatment regimen, the prognosis of IBC remains poor with long-term survival inferior to 50%. Until recently, IBC remained understudied at the molecular level. In the past 10 years, advances have been made in the molecular characterization of the disease. Recently, the use of experimental models and new high-throughput molecular profiling technologies have led to the identification of genes or pathways potentially involved in disease development, which might represent new clinically relevant targets. The aim of this review is to present and discuss what is known about the biology of this particularly aggressive form of breast cancer and to discuss how this knowledge could improve its management.

Pathologic aspects of inflammatory breast cancer: part 2. Biologic insights into its aggressive phenotype

Inflammatory breast cancer (IBC) is the most aggressive and distinct form of primary breast cancer with a peculiar clinical presentation and dismal clinical outcome. This review addresses the pathologic aspects of this entity and discusses the molecular alterations involved in the highly malignant phenotype of IBC.

A stromal gene signature associated with inflammatory breast cancer

The factors that determine whether a breast carcinoma will develop into inflammatory breast cancer (IBC) remain poorly understood. Recent evidence indicates that the tumor stroma influences cancer phenotypes. We tested the hypotheses that the gene expression signature of the tumor stroma is a distinctive feature of IBC. We used laser capture microdissection to obtain enriched populations of tumor epithelial cells and adjacent stromal cells from 15 patients with IBC and 35 patients with invasive, noninflammatory breast cancer (non-IBC). Their mRNA expression profiles were assessed using Affymetrix GeneChips. In addition, a previously established classifier for IBC was evaluated for the resulting data sets. The gene expression profile of the tumor stroma distinguished IBC from non-IBC, and a previously established IBC prediction signature performed better in classifying IBC using the gene expression profile of the tumor stroma than it did using the profile of the tumor epithelium. In a pathway analysis, the genes differentially expressed between IBC and non-IBC tumors clustered in distinct pathways. We identified multiple pathways related to the endoplasmic stress response that could be functionally significant in IBC. Our findings suggest that the gene expression in the tumor stroma may play a role in determining the IBC phenotype.

Nuclear factor-kappaB activation: from bench to bedside

Nuclear factor-kappaB (NF-kappaB) is a proinflammatory transcription factor that has emerged as an important player in the development and progression of malignant cancers. NF-kappaB targets genes that promote tumor cell proliferation, survival, metastasis, inflammation, invasion, and angiogenesis. Constitutive or aberrant activation of NF-kappa is frequently encountered in many human tumors and is associated with a resistant phenotype and poor prognosis. The mechanism of such persistent NF-kappaB activation is not clear but may involve defects in signaling pathways, mutations, or chromosomal rearrangements. Suppression of constitutive NF-kappaB activation inhibits the oncogenic potential of transformed cells and thus makes NF-kappaB an interesting new therapeutic target in cancer.

Phase II Study of Predictive Biomarker Profiles for Response Targeting Human Epidermal Growth Factor Receptor 2 (HER-2) in Advanced Inflammatory Breast Cancer With Lapatinib Monotherapy

Purpose

Inflammatory breast cancer (IBC) is one of the most aggressive forms of breast cancer. Lapatinib, an oral reversible inhibitor of epidermal growth factor receptor (EGFR) and human EGFR 2 (HER-2), demonstrated clinical activity in four of five IBC patients in phase I trials. We conducted a phase II trial to confirm the sensitivity of IBC to lapatinib, to determine whether response is HER-2 or EGFR dependent, and to elucidate a molecular signature predictive of lapatinib sensitivity.

Patients and Methods

Our open-label multicenter phase II trial (EGF103009) assessed clinical activity and safety of lapatinib monotherapy in patients with recurrent or anthracycline-refractory IBC. Patients were assigned to cohorts A (HER-2–overexpressing [HER-2+]) or B(HER-2–/EGFR+) and fresh pretreatment tumor biopsies were collected.

Results

Forty-five patients (30 in cohort A; 15 in cohort B) received lapatinib 1,500 mg once daily continuously. Clinical presentation and biomarker analyses demonstrated a tumor molecular signature consistent with IBC. Lapatinib was generally well tolerated, with primarily grade 1/2 skin and GI toxicities. Fifteen patients (50%) in cohort A had clinical responses to lapatinib in skin and/or measurable disease (according to Response Evaluation Criteria in Solid Tumors) compared with one patient in cohort B. Within cohort A, phosphorylated (p) HER-3 and lack of p53 expression predicted for response to lapatinib (P < .05). Tumors coexpressing pHER-2 and pHER-3 were more likely to respond to lapatinib (nine of 10 v four of 14; P = .0045). Prior trastuzumab therapy and loss of phosphate and tensin homolog 10 (PTEN) did not preclude response to lapatinib.

Conclusion

Lapatinib is well tolerated with clinical activity in heavily pretreated HER-2+, but not EGFR+/HER-2–, IBC. In this study, coexpression of pHER-2 and pHER-3 in tumors seems to predict for a favorable response to lapatinib. These findings warrant further investigation of lapatinib monotherapy or combination therapy in HER-2+ IBC.

Inflammatory breast cancer: current understanding

PURPOSE OF REVIEW

Inflammatory breast cancer is a highly aggressive variant of locally advanced breast cancer that carries a significantly worse prognosis. The purpose of this review is to highlight recent advances in the molecular modus operandi of this particular form of breast cancer.

RECENT FINDINGS

Studies on tumor cell emboli, E-cadherin, chemokine receptors, steroid hormone receptor, angiogenesis, lymphangiogenesis and gene expression all suggest significant differences with noninflammatory breast cancer and are clearly in line with a different pathogenesis of the condition.

SUMMARY

This comprehensive review will hopefully allow for better treatment modalities with targeted approaches as suggested by the early data on anti-vascular endothelial growth factor treatment in inflammatory breast cancer.

NF-kappa B genes have a major role in inflammatory breast cancer

Background

IBC (Inflammatory Breast cancer) is a rare form of breast cancer with a particular phenotype. New molecular targets are needed to improve the treatment of this rapidly fatal disease. Given the role of NF-κB-related genes in cell proliferation, invasiveness, angiogenesis and inflammation, we postulated that they might be deregulated in IBC.

Methods

We measured the mRNA expression levels of 60 NF-κB-related genes by using real-time quantitative RT-PCR in a well-defined series of 35 IBCs, by comparison with 22 stage IIB and III non inflammatory breast cancers. Twenty-four distant metastases of breast cancer served as "poor prognosis" breast tumor controls.

Results

Thirty-five (58%) of the 60 NF-κB-related genes were significantly upregulated in IBC compared with non IBC. The upregulated genes were NF-κB genes (NFKB1, RELA, IKBKG, NFKBIB, NFKB2, REL, CHUK), apoptosis genes (MCL1L, TNFAIP3/A20, GADD45B, FASLG, MCL1S, IER3L, TNFRSF10B/TRAILR2), immune response genes (CD40, CD48, TNFSF11/RANKL, TNFRSF11A/RANK, CCL2/MCP-1, CD40LG, IL15, GBP1), proliferation genes (CCND2, CCND3, CSF1R, CSF1, SOD2), tumor-promoting genes (CXCL12, SELE, TNC, VCAM1, ICAM1, PLAU/UPA) or angiogenesis genes (PTGS2/COX2, CXCL1/GRO1). Only two of these 35 genes (PTGS2/COX2 and CXCL1/GRO1)were also upregulated in breast cancer metastases. We identified a five-gene molecular signature that matched patient outcomes, consisting of IL8 and VEGF plus three NF-κB-unrelated genes that we had previously identified as prognostic markers in the same series of IBC.

Conclusion

The NF-κB pathway appears to play a major role in IBC, possibly contributing to the unusual phenotype and aggressiveness of this form of breast cancer. Some upregulated NF-κB-related genes might serve as novel therapeutic targets in IBC.

Nuclear factor-kappaB signature of inflammatory breast cancer by cDNA microarray validated by quantitative real-time reverse transcription-PCR, immunohistochemistry, and nuclear factor-kappaB DNA-binding

PURPOSE

Inflammatory breast cancer (IBC) is the most aggressive form of locally advanced breast cancer with high metastatic potential. In a previous study, we showed that IBC is a different form of breast cancer compared with non-IBC by cDNA microarray analysis. A list of 756 genes with significant expression differences between IBC and non-IBC was identified. In-depth functional analysis revealed the presence of a high number of nuclear factor-kappaB (NF-kappaB) target genes with elevated expression in IBC versus non-IBC. This led to the hypothesis that NF-kappaB contributes to the phenotype of IBC. The aim of the present study was to further investigate the role of NF-kappaB in IBC.

EXPERIMENTAL DESIGN

Immunohistochemistry and NF-kappaB DNA-binding experiments were done for all NF-kappaB subunits (RelA, RelB, cRel, NFkB1, and NFkB2) using IBC and non-IBC specimens. Transcriptionally active NF-kappaB dimers were identified by means of coexpression analysis. In addition, quantitative real-time reverse transcription-PCR for eight NF-kappaB target genes, selected upon a significant, 3-fold gene expression difference between IBC and non-IBC by cDNA microarray analysis, was done.

RESULTS

We found a significant overexpression for all of eight selected NF-kappaB target genes in IBC compared with non-IBC by quantitative real-time reverse transcription-PCR. In addition, we found a statistically elevated number of immunostained nuclei in IBC compared with non-IBC for RelB (P = 0.038) and NFkB1 (P < 0.001). Immunohistochemical data were further validated by NF-kappaB DNA-binding experiments. Significant correlations between immunohistochemical data and NF-kappaB DNA binding for RelA, RelB, NFkB1, and NFkB2 were found. Transcriptionally active NF-kappaB dimers, composed of specific combinations of NF-kappaB family members, were found in 19 of 44 IBC specimens compared with 2 of 45 non-IBC specimens (P < 0.001). In addition, we found evidence for an estrogen receptor (ER)-mediated inhibition of the NF-kappaB signaling pathway. NF-kappaB target genes were significantly elevated in ER- versus ER+ breast tumors. Also, the amount of immunostained nuclei for RelB (P = 0.025) and NFkB1 (P = 0.031) was higher in ER- breast tumors versus ER+ breast tumors.

CONCLUSIONS

The NF-kappaB transcription factor pathway probably contributes to the phenotype of IBC and possibly offers new options for treatment of patients diagnosed with this aggressive form of breast cancer.

Inflammatory breast cancer (IBC) and patterns of recurrence: understanding the biology of a unique disease

BACKGROUND

Inflammatory breast cancer (IBC) is the most aggressive manifestation of primary breast cancer. The authors compared the prognostic features of IBC and non-IBC locally advanced breast cancer (LABC) to gain insight into the biology of this disease entity.

METHODS

This retrospective analysis consisted of 1071 patients, comprising 240 patients with IBC and 831 patients with non-IBC LABC who were enrolled in 10 consecutive clinical trials (5 from each disease group). All patients received similar multidisciplinary treatment. The authors measured time to disease recurrence for each individual site from the start of treatment to the date of disease recurrence or last follow-up (recurrence-free survival) and overall survival rates to the date of last follow-up or death.

RESULTS

The median follow-up period was 69 months (range, 1-367 months). Pathologically complete response rates were 13.9% and 11.7% in the IBC and non-IBC LABC groups, respectively (P = .42). The 5-year estimates of cumulative incidence of recurrence were 64.8 % and 43.4% (P < .0001), respectively, for IBC and non-IBC LABC. IBC had significantly higher cumulative incidence of locoregional recurrence and distant soft-tissue and bone disease. The 5-year overall survival (OS) rate was 40.5% for the IBC group (95% CI, 34.5%-47.4%) and 63.2% for the non-IBC LABC group (95% CI, 60.0%-66.6%; P < .0001).

CONCLUSIONS

IBC was associated with a worse prognosis and a distinctive pattern of early recurrence compared with LABC. These data suggested that investigating factors affecting "homing" of cancer cells may provide novel treatment strategies for IBC.

Distribution and significance of caveolin 2 expression in normal breast and invasive breast cancer: an immunofluorescence and immunohistochemical analysis

BACKGROUND

The aims of this study were to define the distribution of caveolin 2 (CAV2) in frozen and formalin fixed, paraffin embedded (FFPE) normal breast samples and the significance of CAV2 expression in breast cancer.

METHODS

Caveolin 2 distribution in frozen and paraffin-embedded whole tissue sections of normal breast was evaluated using immunohistochemistry and immunofluorescence, in conjunction with antibodies to define luminal epithelial cells (oestrogen receptor and cytokeratin 8/18) and myoepithelial/ basal cells (cytokeratins 14 and 5/6, p63 and smooth muscle actin). CAV2 expression was also immunohistochemically analysed in two independent cohorts of invasive breast carcinomas (n = 245 and n = 418).

RESULTS

In normal breast, CAV2 was expressed in myoepithelial cells, endothelial cells, fibroblasts and adipocytes. Luminal epithelial cells showed no or only negligible staining. CAV2 expression was observed in 9.6% of all breast cancers and was strongly correlated with high histological grade, lack of oestrogen receptor, progesterone receptor and cyclin D1 expression, and positivity for epidermal growth factor receptor, basal markers, p53 expression, and high proliferation index. Furthermore, CAV2 expression was significantly associated with basal-like immunophenotype and proved to be a prognostic factor for breast cancer-specific survival on univariate analysis.

CONCLUSION

Our results demonstrate that CAV2 is preferentially expressed in basal-like cancers and is associated with poor prognosis. Further in vitro studies are required to determine whether CAV2 has oncogenic properties or is only a surrogate marker of basal-like carcinomas.

Consensus genes of the literature to predict breast cancer recurrence

BACKGROUND

Extensive efforts have been undertaken to discover genes relevant for breast cancer prognosis. Yet, in current opinion, with little overlap in findings. We aimed to reanalyze molecular prediction of breast cancer recurrence.

METHODS

From 44 published gene lists relevant for breast cancer prognosis, we extracted 374 genes, which, besides other quality criteria, are recorded at least twice. From eight published microarray datasets, a single dataset of 1,067 breast cancer patients was created, using transformation to 'probability of expression' scale. For recurrence analysis, the Cox proportional hazards model was applied.

RESULTS

The 374 genes, termed '374 Gene Set', are highly enriched in cell cycle genes. The '374 Gene Set' is significantly associated with breast cancer recurrence (p = 2 x 10(-12), log-rank test) in the meta set of 1,067 patients, showing an estimated Hazard Ratio of recurrence for the 'poor' prognosis group compared to the 'good' prognosis group of 2.03 (95% confidence interval, 1.66-2.48). Notably, the '374 Gene Set' is significantly associated with recurrence in untreated patients. In multivariate analysis, including the standard histopathological parameters, only tumor size and the '374 Gene Set' remain independent predictors of recurrence. External validation further confirmed the prognostic relevance of the gene set (253 patients, p = 0.001, log-rank test).

CONCLUSIONS

The '374 Gene Set' comprises a molecular basis of metastatic breast cancer progression. Starting from this gene set it might be possible to construct a clinically relevant classifier, which then again needs to be validated.

Distinct molecular phenotype of inflammatory breast cancer compared to non-inflammatory breast cancer using Affymetrix-based genome-wide gene-expression analysis

The present study aims at a platform-independent confirmation of previously obtained cDNA microarray results on inflammatory breast cancer (IBC) using Affymetrix chips. Gene-expression data of 19 IBC and 40 non-IBC specimens were subjected to clustering and principal component analysis. The performance of a previously identified IBC signature was tested using clustering and gene set enrichment analysis. The presence of different cell-of-origin subtypes in IBC was investigated and confirmed using immunohistochemistry on a TMA. Differential gene expression was analysed using SAM and topGO was used to identify the fingerprints of a pro-metastatic-signalling pathway. IBC and non-IBC have distinct gene-expression profiles. The differences in gene expression between IBC and non-IBC are captured within an IBC signature, identified in a platform-independent manner. Part of the gene-expression differences between IBC and non-IBC are attributable to the differential presence of the cell-of-origin subtypes, since IBC primarily segregated into the basal-like or ErbB2-overexpressing group. Strikingly, IBC tumour samples more closely resemble the gene-expression profile of T1/T2 tumours than the gene-expression profile or T3/T4 tumours. We identified the insulin-like growth factor-signalling pathway, potentially contributing to the biology of IBC. Our previous results have been validated in a platform-independent manner. The distinct biological behaviour of IBC is reflected in a distinct gene-expression profile. The fact that IBC tumours are quickly arising tumours might explain the close resemblance of the IBC gene-expression profile to the expression profile of T1/T2 tumours.

Molecular profiling in breast cancer

Molecular profiling has provided biological evidence for the heterogeneity of breast cancer through the identification of intrinsic subtypes like Luminal A, Luminal B, HER2+/ER- and basal-like. It has also led to the development of clinically applicable gene expression-based prognostic panels like the Mammaprint and Oncotype Dx. The increasingly sophisticated understanding allowed by this and similar technology promises future individualized therapy.

NF-kappaB activation in inflammatory breast cancer is associated with oestrogen receptor downregulation, secondary to EGFR and/or ErbB2 overexpression and MAPK hyperactivation

Activation of NF-κB in inflammatory breast cancer (IBC) is associated with loss of estrogen receptor (ER) expression, indicating a potential crosstalk between NF-κB and ER. In this study, we examined the activation of NF-κB in IBC and non-IBC with respect to ER and EGFR and/or ErbB2 expression and MAPK hyperactivation. A qRT–PCR based ER signature was evaluated in tumours with and without transcriptionally active NF-κB, as well as correlated with the expression of eight NF-κB target genes. Using a combined ER/NF-κB signature, hierarchical clustering was executed. Hyperactivation of MAPK was investigated using a recently described MAPK signature (Creighton et al, 2006), and was linked to tumour phenotype, ER and EGFR and/or ErbB2 overexpression. The expression of most ER-modulated genes was significantly elevated in breast tumours without transcriptionally active NF-κB. In addition, the expression of most ER-modulated genes was significantly anticorrelated with the expression of most NF-κB target genes, indicating an inverse correlation between ER and NF-κB activation. Clustering using the combined ER and NF-κB signature revealed one cluster mainly characterised by low NF-κB target gene expression and a second one with elevated NF-κB target gene expression. The first cluster was mainly characterised by non-IBC specimens and IHC ER+ breast tumours (13 out of 18 and 15 out of 18 respectively), whereas the second cluster was mainly characterised by IBC specimens and IHC ER− breast tumours (12 out of 19 and 15 out of 19 respectively) (Pearson χ², P<0.0001 and P<0.0001 respectively). Hyperactivation of MAPK was associated with both ER status and tumour phenotype by unsupervised hierarchical clustering using the MAPK signature and was significantly reflected by overexpression of EGFR and/or ErbB2. NF-κB activation is linked to loss of ER expression and activation in IBC and in breast cancer in general. The inverse correlation between NF-κB activation and ER activation is due to EGFR and/or ErbB2 overexpression, resulting in NF-κB activation and ER downregulation.

The use of an in vitro adenosine triphosphate-based chemotherapy response assay to predict chemotherapeutic response in breast cancer

The adenosine triphosphate-based chemotherapy response assay (ATP-CRA) has the advantages of standardization, evaluability, reproducibility, and accuracy, and can be performed on relatively small numbers of tumor cells. A total of 43 patients were enrolled in the present study, and chemosensitivity tests were successfully performed in 40 (93.0%) of these patients. Twenty of the 40 received neoadjuvant chemotherapy or chemotherapy for metastatic breast cancer. The chemotherapy regimens used were doxorubicin plus docetaxel (n=9, 45.0%) or doxorubicin plus paclitaxel (n=11, 55.0%). Mean cell death rate, as determined by ATP-CRA, was lower in non-responders than in responders to therapy (P=0.012). Sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy for ATP-CRA were 78.6%, 100%, 100%, 66.7%, and 85.0%, respectively. Diagnostic accuracy achieved by immunohistochemistry using estrogen receptor or progesterone receptor was lower than that achieved using ATP-CRA. Expression of p53, erb-B2, Ki67, Bcl-2, Bcl-xL, and annexin I was not significantly associated with response to chemotherapy. Our results show that ATP-CRA has high specificity and positive predictive value for predicting response to chemotherapy.

Expression of growth factor and chemokine receptors: new insights in the biology of inflammatory breast cancer

PURPOSE

Recent studies have indicated that expression of chemokine receptors CXCR4 and CCR7 could be an indicator of the metastatic potential of breast cancer. Expression of CXCR4 and CCR7 along with the biomarkers HER2-neu and epidermal growth factor receptor (EGFR) was investigated in inflammatory breast cancer (IBC) to evaluate their prognostic implications.

EXPERIMENTAL DESIGN

CXCR4, CCR7, and EGFR were evaluated by immunohistochemical staining (IHC) of paraffin-embedded tissue sections. HER2-neu amplification was assessed by FISH and/or IHC. All patients received chemotherapy, surgery, and radiation.

RESULTS

Forty-four cases diagnosed with IBC from 1994 to 2002 were included in the study. In all, 18 (40.9%) patients had positive CXCR4, 10 (22.7%) had positive CCR7, 21 (47.7%) had positive HER2-neu, and EGFR was positive in 12 of 40 patients (30%). The 5-year overall survival (OS) was 24.8% for CXCR4-positive disease versus 42.3% for CXCR4-negative patients (P = 0.53) and 20.0% for CCR7-positive disease versus 41.9% for CCR7-negative patients (P = 0.24). EGFR-positive disease had significantly worse OS compared with EGFR-negative disease (P = 0.01).

CONCLUSIONS

These data demonstrate the expression of growth factor and chemokine receptors in IBC. The expression of these receptors is associated with increased risk of recurrence and death, and thus, they may represent potential therapeutic targets in IBC.

Molecular Heterogeneity of Inflammatory Breast Cancer: A Hyperproliferative Phenotype

PURPOSE

Inflammatory breast cancer (IBC) is associated with very poor prognosis. The aims of this study are (a) to prospectively identify differential gene expression patterns associated with IBC and (b) to confirm these pathways using tissue arrays.

EXPERIMENTAL DESIGN

For gene expression analysis, IBC (n=14) was clinically defined as rapid-onset cancer associated with erythema and skin changes, whereas non-IBC patients (n=20) had stage III breast cancers, and cDNA analysis was carried out using the Affymetrix (Santa Clara, CA) HG-U133A microarrays. Tissue arrays were constructed from paraffin-embedded material, and the molecular phenotype of 75 IBC was compared with results from>2,000 non-IBC.

RESULTS

Gene expression analyses indicated that IBC has higher expression of genes associated with increased metabolic rate, lipid signaling, and cell turnover relative to non-IBC tumors. Consistent with the expression analysis, IBC had statistically higher Ki-67 (93% versus 11%; P<0.001). BAX expression, reflecting increased apoptosis and cell turnover, was significantly uniformly higher in almost all IBC (98% versus 66%; P<0.05), whereas the expression of Bcl-2 was not significantly different. IBC tumors were more likely to be steroid hormone receptor negative (estrogen receptor, 49% versus 30%; P=0.002; progesterone receptor, 68% versus 42%; P=0.001). The expression of tyrosine kinases was not significantly different. E-cadherin was found to be expressed in 87% of IBC, whereas the expression p53 was not significantly different.

CONCLUSION

This study is one of the largest molecular analyses of IBC. Both IBC and non-IBC are genetically heterogeneous with consistent differences in the molecular phenotype of IBC.

The current understanding of the molecular determinants of inflammatory breast cancer metastasis

Inflammatory breast cancer is a highly aggressive and metastatic form of locally advanced breast cancer that carries a significantly worse prognosis than non-inflammatory breast cancers. Unfortunately, the molecular basis of this deadly form of breast cancer has been understudied. Over the past 10 years new studies have begun to reveal a unique molecular profile of IBC shedding light on its unique ability to rapidly invade and metastasize via the dermal lymphatic system of the skin overlying the breast. The goal of this review is to introduce IBC to the reader and provide a brief overview of what is known about the metastatic mechanisms of the disease.

Identification of cell-of-origin breast tumor subtypes in inflammatory breast cancer by gene expression profiling

Inflammatory breast cancer (IBC) is an aggressive form of locally advanced breast cancer with high metastatic potential. Most patients have lymph node involvement at the time of diagnosis and 1/3 of the patients have distant metastases. In a previous study, we demonstrated that IBC is a distinct form of breast cancer in comparison with non-IBC. The aim of this study was to investigate the presence of the different molecular subtypes in our data set of 16 IBC and 18 non-IBC specimen. Therefore, we selected an 'intrinsic gene set' of 144 genes, present on our cDNA chips and common to the 'intrinsic gene set' described by Sorlie et al. [PNAS, 2003]. This set of genes was tested for performance in the Norway/Stanford data set by unsupervised hierarchical clustering. Expression centroids were then calculated for the core members of each of the five subclasses in the Norway/Stanford data set and used to classify our own specimens by calculating Spearman correlations between each sample and each centroid. We identified the same cell-of-origin subtypes in IBC as those already described in non-IBC. The classification was in good agreement with immunohistochemical data for estrogen receptor protein expression and cytokeratin 5/6 protein expression. Confirmation was done by an alternative unsupervised hierarchical clustering method. The robustness of this classification was assessed by an unsupervised hierarchical clustering with an alternative gene set of 141 genes related to the cell-of-origin subtypes, selected using a discriminating score and iterative random permutation testing. The contribution of the different cell-of-origin subtypes to the IBC phenotype was investigated by principal component analysis. Generally, the combined ErbB2-overexpressing and basal-like cluster was more expressed in IBC compared to non-IBC, whereas the combined luminal A, luminal B and normal-like cluster was more pronounced in non-IBC compared to IBC. The presence of the same molecular cell-of-origin subtypes in IBC as in non-IBC does not exclude the specific molecular nature of IBC, since gene lists that characterize IBC and non-IBC are entirely different from gene lists that define the different cell-of-origin subtypes, as evidenced by principal component analysis.

Overexpression of caveolin-1 and -2 in cell lines and in human samples of inflammatory breast cancer

PURPOSE

Inflammatory breast cancer (IBC) is the most aggressive form of locally advanced breast cancer (LABC). The IBC phenotype is characterized by an infiltrative growth pattern, increased (lymph)angiogenesis and the propensity to invade dermal lymphatics. In pancreatic cancer, interactions between caveolin-1 and RhoC GTPase, a key molecule in causing the IBC phenotype, regulate tumour cell motility and invasion. In this study we sought to investigate the role of caveolin-1 and -2 in IBC cell lines and in human IBC samples.

EXPERIMENTAL DESIGN

Differential methylation techniques identified the methylation status of the caveolin-1 and -2 promoters in human mammary epithelial cells (HMECs) and the SUM149 cell line. In cell line experiments, caveolin-1 and -2 mRNA and protein expression were compared in HMECs, MCF10A, the SUM102 non-IBC cell lines and 2 IBC cell lines (SUM149 and SUM190). Furthermore, caveolin-1 and -2 mRNA and protein expression were compared in human IBC and non-IBC samples using cDNA microarray, real-time qRT-PCR and immunohistochemistry. Results were correlated with RhoC protein expression data.

RESULTS

In the SUM149 cell line, the caveolin-1 and -2 promoter sites were hypomethylated. A significantly increased expression of caveolin-1 and -2, both at the mRNA and protein level was found in IBC cell lines and in human samples of IBC: caveolin-1 and -2 mRNA were respectively 1.7 (p = 0.02) and 2.2 (p = 0.03) fold more expressed in IBC compared to non IBC and at the protein level, 41.4% of IBC specimens expressed either caveolin-1 or -2, compared to 15.6% of non-IBC specimens (p = 0.03). Furthermore a correlation was found between RhoC protein expression and caveolin-1 (p = 0.1) or caveolin-2 (p = 0.09) or either caveolin-1 or -2 protein expression (p = 0.04).

CONCLUSIONS

Although considered a tumour suppressor in breast cancer, we demonstrated overexpression of caveolin-1 and -2 in IBC cell lines and in human samples of IBC, most likely due to hypomethylation of their respective promoters. These results confirm the distinct molecular signature of IBC. Our data further suggest interaction between RhoC GTPase and the caveolins in IBC.