Tim J. A. Dekker

Nuclear receptor NR4A1 promotes breast cancer invasion and metastasis by activating TGF-β signalling

In advanced cancers, the TGF-β pathway acts as an oncogenic factor and is considered to be a therapeutic target. Here using a genome-wide cDNA screen, we identify nuclear receptor NR4A1 as a strong activator of TGF-β signalling. NR4A1 promotes TGF-β/SMAD signalling by facilitating AXIN2-RNF12/ARKADIA-induced SMAD7 degradation. NR4A1 interacts with SMAD7 and AXIN2, and potently and directly induces AXIN2 expression. Whereas loss of NR4A1 inhibits TGF-β-induced epithelial-to-mesenchymal transition and metastasis, slight NR4A1 ectopic expression stimulates metastasis in a TGF-β-dependent manner. Importantly, inflammatory cytokines potently induce NR4A1 expression, and potentiate TGF-β-mediated breast cancer cell migration, invasion and metastasis in vitro and in vivo. Notably, NR4A1 expression is elevated in breast cancer patients with high immune infiltration and its expression weakly correlates with phosphorylated SMAD2 levels, and is an indicator of poor prognosis. Our results uncover inflammation-induced NR4A1 as an important determinant for hyperactivation of pro-oncogenic TGF-β signalling in breast cancer.

Multicenter Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry Imaging (MALDI MSI) Identifies Proteomic Differences in Breast-Cancer-Associated Stroma

MALDI mass spectrometry imaging (MSI) has rapidly established itself as a powerful biomarker discovery tool. To date, no formal investigation has assessed the center-to-center comparability of MALDI MSI experiments, an essential step for it to develop into a new diagnostic method. To test such capabilities, we have performed a multicenter study focused on biomarkers of stromal activation in breast cancer. MALDI MSI experiments were performed in two centers using independent tissue banks, infrastructure, methods, and practitioners. One of the data sets was used for discovery and the other for validation. Areas of intra- and extratumoral stroma were selected, and their protein signals were compared. Four protein signals were found to be significantly associated with tumor-associated stroma in the discovery data set measured in Munich. Three of these peaks were also detected in the independent validation data set measured in Leiden, all of which were also significantly associated with intratumoral stroma. Hierarchical clustering displayed 100% accuracy in the Munich MSI data set and 80.9% accuracy in the Leiden MSI data set. The association of one of the identified mass signals (PA28) with stromal activation was confirmed with immunohistochemistry performed on 20 breast tumors. Independent and international MALDI MSI investigations could identify validated biomarkers of stromal activation.

Determining sensitivity and specificity of HER2 testing in breast cancer using a tissue micro-array approach

IntroductionOverexpression of the human epidermal growth factor receptor 2 (HER2) as a result of HER2 gene amplification is associated with a relatively poor prognosis in breast cancer and is predictive of HER2-targeting therapy response. False-positive rates of up to 20% for HER2 testing have been described. HER2-testing laboratories are therefore encouraged to participate in external quality control schemes in order to improve HER2-testing standardization.MethodsThis study investigated the feasibility of retesting large numbers of invasive breast cancers for HER2 status on tissue micro-array (TMA) as part of a quality control scheme. For this assessment different HER2 testing methods were used including HER2 detecting antibodies SP3, 4B5, Herceptest and mono color silver in situ hybridization (SISH) and dual color SISH. Final HER2 status for each tumor on the TMA was compared to the local testing result for the same tumor. Discordances between these two results were investigated further by staining whole tumor sections.ResultsFor this study, 1,210 invasive breast carcinomas of patients treated in six hospitals between 2006 and 2008 were evaluated. Results from the three immunohistochemistry (IHC) and two in situ hybridization (ISH) assays performed on the TMAs were compared. The final HER2 status on TMA was determined with SP3, 4B5 and mono color SISH. Concordance between local HER2 test results and TMA retesting was 98.0%. Discordant results between local and TMA retesting were found in 20 tumors (2.0%). False positive HER2 IHC results were identified in 13 (1.3%) tumors; false negative IHC results in seven (0.7%) tumors.ConclusionsRetesting large volumes of HER2 classified breast carcinomas was found to be feasible and can be reliably performed by staining TMAs with SP3, 4B5 and mono color SISH in combination with full-sized slides for discordant cases. The frequency of false-positive results was lower than previously reported in the literature. This method is now offered to other HER2-testing laboratories.

The prognostic role of TGF-β signaling pathway in breast cancer patients

BACKGROUND The transforming growth factor-β (TGF-β) pathway has dual effects on tumor growth. Seemingly, discordant results have been published on the relation between TGF-β signaling markers and prognosis in breast cancer. Improved prognostic information for breast cancer patients might be obtained by assessing interactions among TGF-β signaling biomarkers. PATIENTS AND METHODS The expression of nuclear Smad4, nuclear phosphorylated-Smad2 (p-Smad2), and the membranous expression of TGF-β receptors I and II (TβRI and TβRII) was determined on a tissue microarray of 574 breast carcinomas. Tumors were stratified according to the Smad4 expression in combination with p-Smad2 expression or Smad4 in combination with the expression of both TGF-β receptors. RESULTS Tumors with high expression of TβRII, TβRI and TβRII, and p-Smad2 (P = 0.018, 0.005, and 0.022, respectively), and low expression of Smad4 (P = 0.005) had an unfavorable prognosis concerning progression-free survival. Low Smad4 expression combined with high p-Smad2 expression or low expression of Smad4 combined with high expression of both TGF-β receptors displayed an increased hazard ratio of 3.04 [95% confidence interval (CI) 1.390-6.658] and 2.20 (95% CI 1.464-3.307), respectively, for disease relapse. CONCLUSIONS Combining TGF-β biomarkers provides prognostic information for patients with stage I-III breast cancer. This can identify patients at increased risk for disease recurrence that might therefore be candidates for additional treatment.BACKGROUND The transforming growth factor-β (TGF-β) pathway has dual effects on tumor growth. Seemingly, discordant results have been published on the relation between TGF-β signaling markers and prognosis in breast cancer. Improved prognostic information for breast cancer patients might be obtained by assessing interactions among TGF-β signaling biomarkers. PATIENTS AND METHODS The expression of nuclear Smad4, nuclear phosphorylated-Smad2 (p-Smad2), and the membranous expression of TGF-β receptors I and II (TβRI and TβRII) was determined on a tissue microarray of 574 breast carcinomas. Tumors were stratified according to the Smad4 expression in combination with p-Smad2 expression or Smad4 in combination with the expression of both TGF-β receptors. RESULTS Tumors with high expression of TβRII, TβRI and TβRII, and p-Smad2 (P = 0.018, 0.005, and 0.022, respectively), and low expression of Smad4 (P = 0.005) had an unfavorable prognosis concerning progression-free survival. Low Smad4 expression combined with high p-Smad2 expression or low expression of Smad4 combined with high expression of both TGF-β receptors displayed an increased hazard ratio of 3.04 [95% confidence interval (CI) 1.390-6.658] and 2.20 (95% CI 1.464-3.307), respectively, for disease relapse. CONCLUSIONS Combining TGF-β biomarkers provides prognostic information for patients with stage I-III breast cancer. This can identify patients at increased risk for disease recurrence that might therefore be candidates for additional treatment.

Proteomic Serum Biomarkers and Their Potential Application in Cancer Screening Programs

Early diagnosis of cancer is of pivotal importance to reduce disease-related mortality. There is great need for non-invasive screening methods, yet current screening protocols have limited sensitivity and specificity. The use of serum biomarkers to discriminate cancer patients from healthy persons might be a tool to improve screening programs. Mass spectrometry based proteomics is widely applied as a technology for mapping and identifying peptides and proteins in body fluids. One commonly used approach in proteomics is peptide and protein profiling. Here, we present an overview of profiling methods that have the potential for implementation in a clinical setting and in national screening programs.

Reliability of core needle biopsy for determining ER and HER2 status in breast cancer

BACKGROUND Several studies have assessed the concordance of estrogen receptor (ER) and human epidermal growth factor receptor 2 (HER2) status between core needle biopsy (CNB) and resection specimens, usually in small patient series and with discordant results. PATIENTS AND METHODS ER and HER2 status determined on CNB and tissue micro-arrays of resected tumors were compared for patients treated at the Leiden University Medical Center (LUMC). When results were discordant, whole-sized slides were analyzed. Additionally, literature was searched for published patient series and combined with our data to assess the concordance of ER and HER2 determination between CNB and resection specimens. RESULTS In the LUMC series, concordance for ER status was 99.1%. Combined concordance from 20 studies and the LUMC patient series was 93.7%. For HER2 testing, concordance was 96.2% for patients in the LUMC series. Our study and three others have investigated the concordance when HER2 was determined according to the American Society of Clinical Oncology and College of Pathology guidelines and overall concordance was 97.8%. CONCLUSIONS Concordance between CNB and surgical specimens was high for both ER and HER2 testing. However, we recommend retesting ER-negative CNB results on the surgical specimen and performing in situ hybridization assays on HER2 immunohistochemistry 3+ CNBs to confirm HER2 status.

Towards imaging metabolic pathways in tissues

Matrix-assisted laser desorption/ionization (MALDI) mass spectrometry imaging using 9-aminoacridine as the matrix leads to the detection of low mass metabolites and lipids directly from cancer tissues. These included lactate and pyruvate for studying the Warburg effect, as well as succinate and fumarate, metabolites whose accumulation is associated with specific syndromes. By using the pathway information present in the human metabolome database, it was possible to identify regions within tumor tissue samples with distinct metabolic signatures that were consistent with known tumor biology. We present a data analysis workflow for assessing metabolic pathways in their histopathological context.

Disorganised stroma determined on pre-treatment breast cancer biopsies is associated with poor response to neoadjuvant chemotherapy: Results from the NEOZOTAC trial

The tumor‐associated stroma is of importance for tumor progression and is generally accepted to have a significant influence on patient prognosis. However, little is known regarding specific features of tumor‐associated stromal tissues and response to (neoadjuvant) chemotherapy. This study investigated the predictive value of extracellular matrix organization on response to chemotherapy in patients treated in the NEOZOTAC trial.

Comment on: The prognostic significance of tumour-stroma ratio in oestrogen receptor-positive breast cancer.

Comment on: The prognostic significance of tumour-stroma ratio in oestrogen receptor-positive breast cancer

The prognostic value of tumor-stroma ratio in tumor-positive axillary lymph nodes of breast cancer patients: Prognostic value of tumor-stroma ratio

The tumor–stroma ratio (TSR) has previously been found to be a strong prognostic parameter in primary breast cancer tumors. Since the presence of tumor cells in lymph nodes is important for clinical decision making, the influence of TSR in the primary breast tumor combined with the TSR in tumor‐positive lymph nodes on prognosis was evaluated. Women with invasive breast cancer without distant metastasis who underwent an axillary lymph node dissection between 1985 and 1994 at the Leiden University Medical Center were retrospectively analyzed. TSR assessment was performed on hematoxylin and eosin stained tissue slides. In total, 87 (45.5%) primary tumors were scored as stroma‐low and 104 (54.5%) as stroma‐high. Patients with a high stromal percentage in the primary tumors had a statistically significant worse relapse free period (RFP) compared to stroma‐low tumors (HR 1.97, 95% CI 1.37–2.82, p < 0.001). A total number of 915 lymph nodes were assessed for TSR. In 101 (52.9%) patients, heterogeneity was observed between stroma percentage category in primary tumor and lymph nodes. The combination of TSR of the primary tumor combined with TSR of tumor‐positive lymph nodes strengthened each other as independent prognostic parameter for RFP (p = 0.019). Patients with primary tumor stroma‐low/lymph nodes stroma‐low tumors showed strongly improved RFP rates compared to patients with primary tumor stroma‐high/lymph node stroma‐high tumors with 10‐year percentages of 58 versus 8%, respectively. Assessing the TSR on tumor‐positive lymph nodes can provide additional prognostic information. Stromal activation strongly differs between primary tumors and lymph node metastasis.