Jorge F Cameselle-Teijeiro

Breast cancer stem cell markers CD44, CD24 and ALDH1: expression distribution within intrinsic molecular subtype

Background and Aim The study of CD44/CD24 and ALDH1 expression is the most accurate method to identify cancer stem cells (CSC) from breast cancer populations. However, the overlap between CD44+CD24−/low and ALDH1high CSC phenotypes in breast cancer seems to be very small, as well as their distribution among intrinsic breast cancer subtypes. Due to this discrepancy, it is imperative to improve the understanding of breast CSC marker distribution. Methods 466 invasive breast carcinomas and eight breast cancer cell lines were analysed for the expression of CD44, CD24 and ALDH1, to evaluate their distribution among the distinct molecular subtypes. Results Basal-like tumours (76.5%) contained the higher percentage of cells with the CSC phenotype CD44+CD24−/low (p<0.0001). From ALDH1-positive cases, 39.4% were also basal-like tumours (p<0.0001). The analysis of breast cancer cell lines indicated that luminal cell lines are mainly enriched in a CD44−/lowCD24+ cell population, basal/mesenchymal breast cancer cell lines are enriched in the CD44+CD24−/low phenotype, whereas the remaining basal/epithelial cell lines are mainly positive for both markers. ALDH1 activity was mainly found in HER-OE and basal/epithelial breast cancer cell. Conclusions CD44+CD24−/low and ALDH1+ phenotypes seem to identify CSC with distinct levels of differentiation. It seems that the paramount method and biomarkers that identify breast CSC within the distinct molecular subtypes need to be better explored, because it is pivotal to translate the CSC concept to clinical practice. In the future, the recognition of reliable markers to distinguish the CSC pool in each molecular subtype will be decisive for the development of specific target therapies.

Importance of TP53 codon 72 and intron 3 duplication 16bp polymorphisms in prediction of susceptibility on breast cancer

BackgroundTP53 is one of major tumour suppressor genes being essential in preservation of genome integrity. Two very common polymorphisms have been demonstrated to contribute to cancer susceptibility and tumour behaviour. The purpose of this study was to evaluate the role of Arg72Pro and PIN3 Ins16bp polymorphisms in TP53 gene as genetic susceptibility and predictive markers to breast cancer.MethodsWe analysed DNA samples from 264 breast cancer patients and 440 controls, for TP53 Arg72Pro and PIN3 Ins16bp polymorphisms using PCR-RFLP.ResultsWe observed that women with A2A2 genotype have increased risk for developing breast cancer, either in women with or without familial history (FH) of the disease (OR = 4.40, 95% CI 1.60–12.0; p = 0.004; OR = 3.88, 95% CI 1.18–12.8; p = 0.026, respectively). In haplotype analysis, statistically significant differences were found between TP53 Arg-A2 haplotype frequencies and familial breast cancer cases and the respective control group (OR = 2.10, 95% CI 1.08–4.06; p = 0.028). Furthermore, both TP53 polymorphisms are associated with higher incidence of lymph node metastases.ConclusionOur findings suggest TP53 PIN3 Ins16bp polymorphism as a real risk modifier in breast cancer disease, either in sporadic and familial breast cancer. Furthermore, both TP53 polymorphisms are associated with higher incidence of lymph node metastases.

Immunohistochemical detection of p53 in differentiated, poorly differentiated and undifferentiated carcinomas of the thyroid

In an attempt to find whether or not p53 immunoreactivity in the thyroid gland is restricted to undifferentiated carcinomas and to evaluate the putative prognostic usefulness of its detection, we investigated p53 immunoreactivity in a series of 14 benign thyroid lesions and 65 thyroid carcinomas (12 papillary; six minimally invasive follicular; four widely invasive follicular; 31 poorly differentiated and 12 undifferentiated tumours). Unequivocal nuclear immunostaining for p53 was observed in two widely invasive follicular carcinoma (20.0%), five poorly differentiated carcinomas (16.1%) and in 10 undifferentiated carcinomas (83.3%). The percentage of immunoreactive cells was much smaller in the former groups than in undifferentiated carcinomas. Despite a trend to a more aggressive behaviour of the p53 immunoreactive cases no significant differences in the outcome of patients with positive and negative tumours was found when the comparison was made within each category of carcinomas. We conclude that p53 immunoreactivity can be detected both in undifferentiated carcinomas and in some differentiated and poorly differentiated thyroid carcinomas. Larger series of cases are necessary to evaluate the prognostic usefulness of this finding.

Telomerase expression and proliferative activity suggest a stem cell role for thyroid solid cell nests.

Solid cell nests of the human thyroid gland are composed of main cells and C cells. In order to investigate the putative stem cell nature of the role for solid cell nests, we evaluated the histological features, and the immunohistochemical expression of p63, bcl-2, telomerase catalytic subunit, and two proliferative markers (Ki-67 and minichromosome maintenance protein 2), in a series of 24 cases of solid cell nests. Proliferative indices were determined in (a) solid cell nests, (b) thyroid follicular cells in the vicinity of solid cell nests within a low-power field, and (c) distant thyroid tissue, at a distance of at least three low-power fields from solid cell nests. In 15 cases of solid cell nests (62.5%), mixed follicles were observed; papillary formations were observed in four cases (16.6%), and ciliated cells were observed in the lining of microcysts associated with two cases (8.3%). Salivary gland-type tissue, cartilage islands, adipose and fibrous tissues, and small nerves were also associated with some cases of solid cell nests. We observed that the main cells of the solid cell nests express consistently telomerase, although at lower levels than p63, and show strong cytoplasmic immunoreactivity for bcl-2, which is associated with an increased differentiation potential. We also observed that despite their relative low proliferative index, main cells of the solid cell nests display higher proliferation than follicular cells in the vicinity and follicular cells in more distant thyroid tissue. We conclude that main cells of the solid cell nests apparently harbor the minimal properties of a stem cell phenotype (capacity for both self-renewal, conferred by telomerase activity, and differentiation to one or more than one type of specialized cells, given by the high expression of p63 and bcl-2) and may thus represent a pool of stem cells of the adult thyroid.

P‐cadherin functional role is dependent on E‐cadherin cellular context: a proof of concept using the breast cancer model

P‐cadherin overexpression is associated with worse breast cancer survival, being a poor prognostic marker as well as a putative therapeutic target for the aggressive triple‐negative and basal‐like carcinomas (TNBCs). Previously, we have shown that P‐cadherin promotes breast cancer invasion of cells where membrane E‐cadherin was maintained; however, it suppresses invasion in models without endogenous cadherins, like melanomas. Here, we investigated if P‐cadherin expression would interfere with the normal adhesion complex and which were the cellular/molecular consequences, constituting, in this way, a new mechanism by which E‐cadherin invasive‐suppressor function was disrupted. Using breast TNBC models, we demonstrated, for the first time, that P‐cadherin co‐localizes with E‐cadherin, promoting cell invasion due to the disruption caused in the interaction between E‐cadherin and cytoplasmic catenins. P‐cadherin also induces cell migration and survival, modifying the expression profile of cells expressing wild‐type E‐cadherin and contributing to alter their cellular behaviour. Additionally, E‐ and P‐cadherin co‐expressing cells significantly enhanced in vivo tumour growth, compared with cells expressing only E‐ or only P‐cadherin. Finally, we still found that co‐expression of both molecules was significantly correlated with high‐grade breast carcinomas, biologically aggressive, and with poor patient survival, being a strong prognostic factor in this disease. Our results show a role for E‐ and P‐cadherin co‐expression in breast cancer progression and highlight the potential benefit of targeting P‐cadherin in the aggressive tumours expressing high levels of this protein. Copyright

P‐Cadherin Is Coexpressed with CD44 and CD49f and Mediates Stem Cell Properties in Basal‐like Breast Cancer

Although the luminal progenitor cell of the normal mammary gland hierarchy has been proposed as the cell‐of‐origin for basal‐like breast cancers, finding the cancer stem cell (CSC) phenotype for this malignancy has proven a difficult task, mostly due to the lack of specific markers. Recently, basal‐like sporadic and familial cases of breast cancer have been linked to BRCA1 gene inactivation, which enables the upregulation of the target‐repressed CDH3/P‐cadherin gene, an important biomarker of basal‐like breast carcinomas. Previously, we demonstrated that P‐cadherin overexpression can mediate aggressive behavior in these tumors. Thus, our aim was to test whether P‐cadherin mediates stem cell properties in basal‐like breast carcinomas. Using a series of breast cancer cell lines and primary tumors, we showed that P‐cadherin was directly associated with the expression of the breast stem markers CD44, CD49f, and aldehyde dehydrogenase 1 in the basal subtype. Moreover, cell population enriched for P‐cadherin expression comprised increased in vitro mammosphere‐forming efficiency and capacity to grow colonies in three‐dimensional cultures as well as greater tumorigenicity. Importantly, an association was found with stem‐/progenitor‐like phenotypes of the breast, including the luminal progenitor population, CD49f+CD24+. Additionally, P‐cadherin expression conferred resistance to x‐ray‐induced cell death, sustaining a role for this molecule in another stem cell property. In summary, we demonstrated, for the first time, that P‐cadherin mediates stem cell properties, which could be explored in order to better define the CSC phenotype of basal‐like breast tumors and the cell‐of‐origin of this malignancy. STEM CELLS 2012;30:854–864

Immunohistochemical features of claudin-low intrinsic subtype in metaplastic breast carcinomas.

PURPOSE The claudin-low molecular subtype of breast cancer includes triple negative invasive carcinomas, with a high frequency of metaplastic and medullary features. The aim of this study was to evaluate the immunohistochemistry expression of claudins in a series of metaplastic breast carcinomas. We also assessed other claudin-low features, such as the cancer stem cell-like and epithelial-to-mesenchymal transition phenotypes. RESULTS The majority of the cases showed weak or negative staining for membrane claudins expression. We found 76.9% (10/13) low expressing cases for claudin-1, 84.6% (11/13) for claudin-3 and claudin-4, and 92.3% (12/13) for claudin-7. Regarding the cancer stem cell marker ALDH1, 30.8% (4/13) showed positive staining. We also showed that the majority of the cases presented a CD44(+)CD24(-/low) phenotype, positivity for vimentin and lack of E-cadherin expression. Interestingly, these claudin-low molecular features were specific of the mesenchymal component of metaplastic breast carcinomas, since its frequency was very low in other breast cancer molecular subtypes, as luminal, HER2-overexpressing and non-metaplastic triple negative tumors. CONCLUSIONS The negative/low expression of claudins and E-cadherin, high levels of vimentin, and the breast cancer stem cell phenotype suggests that metaplastic breast carcinomas have similar features to the ones included in the claudin-low molecular subtype, specially their mesenchymal components.

XRCC1 Arg399Gln and RAD51 5'UTR G135C polymorphisms and their outcome in tumor aggressiveness and survival of Portuguese breast cancer patients.

Breast cancer (BC) is the most common type of cancer in female, including Portugal, where this disease presents the highest incidence and mortality rates [1]. BC risk factors, like prolonged exposure to estrogen and/or ionizing radiation, BRCA1, BRCA2, TP53, ATM and CHEK2 mutations [2, 3], are related with an increased chance of DNA damage, acting as initiators of cellular alterations. DNA repair pathways are critical processes in order to maintain genome integrity. Therefore, genetic polymorphisms in DNA repair genes are common events [4]. We previously showed correlations of some of these genetic variations, as XRCC1 Arg399Gln, RAD51 5’UTR G135C and XRCC3 Thr241Met, with changeable BC susceptibility [5]. In the present study, we aimed to investigate the possible correlations between DNA repair polymorphisms with BC clinico-pathological phenotypes, identifying subgroups of patients according to their genetic background. We analysed DNA from 165 BC patients, including 33 unrelated family history (FH) and 132 sporadic BC cases from Surgical Departments of S. Joao Hospital and the Oncology Portuguese Institute, at Porto. All participants provided informed consent. Patients presented a mean age of 51.01 years (standard deviation (SD) ± 12.68). We determined XRCC1 Arg399Gln, RAD51 5’0UTR G135C and XRCC3 Thr241Met genotypes by PCR-RFLP technique, as previously described [5]. Chi-square (v test) analysis was used to compare different variables. Logistic regression analysis was applied to calculate the adjusted p value for age and FH in identification of subgroups of patients according to genotypes. The Kaplan-Meier method was used to estimate overall survival (OS). OS was defined as minimal 60 months follow-up, from clinical diagnosis until death or censorship (were alive at the end of the follow-up time period). Differences on OS were obtained by Log Rank test. The correlation of the analysed DNA repair polymorphisms with some clinical-pathological features is presented in Table 1. According to our results, XRCC1 Gln/Gln genotype seems to be associated with less aggressive tumors, since this genotype was correlated with well differentiated tumors (p = 0.022 adjusted for age and BC FH, using logistic regression analysis). Deficient efficiency of the XRCC1 protein has been described in XRCC1 Gln399 variant [6, 7]. Furthermore, repair of more complex base lesions [8, 9, 10] by base excision repair (BER) pathway can potentially convert S. Costa ICVS, Life and Health Sciences Research Institute, Health Science School, Minho University, 4710-057, Braga, Portugal

Claudin expression in breast cancer: high or low, what to expect?

The evaluation of claudins (CLDNs) expression pattern in tumours can be important to understand breast carcinogenesis. The study of CLDNs became more appealing since it was found that CLDN3 and CLDN4 are putative therapeutic targets for Clostridium perfrigens enterotoxin (CPE), as well as for monoclonal antibody-based therapy. Moreover, the recently characterized CLDN-low molecular subgroup of breast tumours increased the interest in these molecules. Based on these facts, our aim was to explore the pattern of expression of CLDNs among a large series of invasive breast carcinomas. We also analysed the correlation between the combinatorial expression of CLDN3/CLDN4 and classical prognostic factors and biological markers. In addition, we also compared the characteristics of tumours with low expression of CLDN3, CLDN4 and CLDN7, assessed by immunohistochemistry (IHC), and the ones from CLDN-low subgroup of tumours previously defined by genomic assays. The combinatorial analysis of the expression of CLDN3/CLDN4 showed a significant association between high CLDN3/CLDN4 levels and triple-negative tumours, as well as with worse patient outcome. This combined analysis may provide useful information for breast carcinomas, since these two CLDN members are putative therapeutic targets. Comparing tumours with low expression of CLDN3, CLDN4 and CLDN7 with tumours previously referred to as CLDN-low by genomic assays, we demonstrated that the single IHC evaluation of these three specific CLDNs is insufficient to identify the CLDN-low molecular subtype of breast tumours. The analysis of several other molecular markers, such as EMT (epithelial-to-mesenchymal transition) and CSC (cancer stem cell) markers should probably be added to improve the identification of this subgroup of tumours by IHC, which probably are enriched in carcinomas with metaplastic differentiation.

Altered PPP2R2A and Cyclin D1 expression defines a subgroup of aggressive luminal-like breast cancer

BackgroundPPP2R2A deletions were recently linked to a subgroup of luminal breast carcinoma (BC) that exhibits poor survival. This subgroup also exhibited amplification of a chromosome region containing the Cyclin D1 coding gene, CCND1. Therefore, we aimed to investigate whether a combination of PPP2R2A (B55α) and Cyclin D1 expression statuses evaluated by immunohistochemistry (IHC) could define a subgroup of luminal BC that exhibits poor survival.MethodsFirst we conducted a retrospective cohort study using sequencing data from The Cancer Genome Atlas initiative to correlate PPP2R2A copy number alteration (CNA) status with its expression level and the corresponding overall survival (OS). Next, also using a retrospective cohort study design, we evaluated the PPP2R2A (B55α) expression levels by IHC in a total of 807 BC patients from two independent cohorts (discovery cohort n = 349 and validation cohort n = 458). Cyclin D1 expression was also evaluated, and the PPP2R2A (B55α)-/low/Cyclin D1high phenotype was evaluated as a predictor of disease-free survival (DFS) and OS in luminal-like BC patients.ResultsDeletions in the PPP2R2A gene strongly correlate with lower mRNA expression and poorer OS. PPP2R2A (B55α)-/low carcinomas have significantly shorter DFS and OS. Furthermore, in univariate analysis, the PPP2R2A (B55α)-/low/Cyclin D1high phenotype is significantly associated with poorer DFS and OS. In a multivariate analysis, the PPP2R2A (B55α)-/low/Cyclin D1high phenotype is significantly associated with poor DFS, thus defining a group of luminal-like BC with higher risk of relapse.ConclusionWe demonstrate that BCs harboring PPP2R2A deletions are associated with worse OS. Moreover, this is the first study to demonstrate that the combination of altered PPP2R2A (B55α) and high Cyclin D1 expression by IHC defines a subgroup of luminal-like BC patients with a high risk of relapse and death.