Sustained postconfluent culture of human mammary epithelial cells enriches for luminal and c-Kit+ subtypes

BACKGROUND

A challenge in human mammary epithelial cell (HMEC) culture is sustaining the representation of competing luminal, myoepithelial, and progenitor lineages over time. As cells replicate in culture, myoepithelial cells come to dominate the composition of the culture with serial passaging. This drift in composition presents a challenge for studying luminal and progenitor cells, which are prospective cells of origin for most breast cancer subtypes.

METHODS

We demonstrate the use of postconfluent culture on HMECs. Postconfluent culture entails culturing HMECs for 2-5 weeks without passaging but maintaining frequent feedings in low-stress M87A culture medium. In contrast, standard HMEC culture entails enzymatic subculturing every 3-5 days to maintain subconfluent density.

RESULTS

When compared to standard HMEC culture, postconfluent culture yields increased proportions of luminal cells and c-Kit+ progenitor cells. Postconfluent cultures develop a distinct multilayered morphology with individual cells showing decreased physical deformability as compared to cells in standard culture. Gene expression analysis of postconfluent cells shows increased expression of lineage-specific markers and extracellular matrix components.

CONCLUSIONS

Postconfluent culture is a novel, useful strategy for altering the lineage composition of HMECs, by increasing the proportional representation of luminal and progenitor cells. We speculate that postconfluent culture creates a microenvironment with cellular composition closer to the physiological state and eases the isolation of scarce cell subtypes. As such, postconfluent culture is a valuable tool for researchers using HMECs for breast cancer research.

PI3K/AKT Signaling in Breast Cancer Molecular Subtyping and Lymph Node Involvement

Lymph node metastatic involvement persists to be among the most important predictors of recurrence and survival in breast carcinoma (BC). This study is aimed at investigating possible gene expression differences in primary BC between patients with or without lymph node involvement at the time of diagnosis. In a retrospective study, we investigated the potential prognostic role of 9 candidate biomarkers at the mRNA level in a cohort of 305 breast cancer patients, 151 lymph node-negative (LN-) and 154 lymph node-positive (LN+) individuals. The analyzed genes belonged to the RAS pathway (RAF1, ERBB2, PIK3CB, AKT1, AKT2, and AKT3), RB pathway (RB1 and CDK2), and cellular differentiation (KRT8). Their expression profiles were investigated by RT-qPCR and were correlated to immunohistochemically based molecular subtypes and BC clinical and pathological features. The differential expression of several genes in the primary tumor tissue was related to the LN involvement. Some of those genes, including PIK3CB, RB1, and AKT3, were more expressed in LN- BC patients, while some others, notably ERBB2 and AKT1, in LN+ ones. Among the candidate biomarkers, the expression levels of AKT isoforms influenced also patients' survival rates. In detail, higher expression levels of AKT1 and AKT2 negatively influenced overall patients' survival, and in particular, AKT2 expression levels defined a group of luminal B BC patients with shorter cancer-specific survival. On the contrary, longer cancer-specific survival was recorded in luminal A BC patients with higher expression levels of AKT3. That finding was also confirmed by Cox multivariate analysis. The same AKT3 resulted to be a possible candidate predictive biomarker for Tamoxifen response. In conclusion, our study highlighted the complex regulation of the PI3K/AKT pathway in BC and its differences in BC patients with and without lymph node involvement.

Cytoskeletal and extracellular matrix proteins as markers for metastatic triple negative breast cancer

Objective

This study investigated immunohistochemical staining results of two cytoskeletal proteins (vimentin and cytokeratin-18) and two extracellular matrix proteins (fibronectin-1 and laminin-1 receptor) in different stages of triple negative breast cancer.

Methods

Forty triple negative cancerous breast tissues from patients diagnosed as stage 2A (15), 2B (nine), 3A (10), 3B (four), and 3C (two) were included in this study and were compared with 42 normal breast tissues. Immunohistochemistry results were statistically analyzed using the t-test percent of the StatPac program.

Results

The percentages of positive staining in cancerous tissues for all of the studied parameters were significantly greater than their percentages in normal tissues, except for vimentin. All cancerous tissues from patients diagnosed as stage 3A, 3B, and 3C were positive for both fibronectin-1 and laminin-1 receptor.

Conclusion

Fibronectin-1 and laminin-1 receptor are promising markers for stage 3 triple negative breast cancer.

Protein biomarkers for subtyping breast cancer and implications for future research

INTRODUCTION

Breast cancer subtypes are currently defined by a combination of morphologic, genomic, and proteomic characteristics. These subtypes provide a molecular portrait of the tumor that aids diagnosis, prognosis, and treatment escalation/de-escalation options. Gene expression signatures describing intrinsic breast cancer subtypes for predicting risk of recurrence have been rapidly adopted in the clinic. Despite the use of subtype classifications, many patients develop drug resistance, breast cancer recurrence, or therapy failure. Areas covered: This review provides a summary of immunohistochemistry, reverse phase protein array, mass spectrometry, and integrative studies that are revealing differences in biological functions within and between breast cancer subtypes. We conclude with a discussion of rigor and reproducibility for proteomic-based biomarker discovery. Expert commentary: Innovations in proteomics, including implementation of assay guidelines and standards, are facilitating refinement of breast cancer subtypes. Proteomic and phosphoproteomic information distinguish biologically functional subtypes, are predictive of recurrence, and indicate likelihood of drug resistance. Actionable, activated signal transduction pathways can now be quantified and characterized. Proteomic biomarker validation in large, well-designed studies should become a public health priority to capitalize on the wealth of information gleaned from the proteome.

Detection of Cytokeratin 19 mRNA and CYFRA 21–1 (Cytokeratin 19 Fragments) in Blood of Tunisian Women with Breast Cancer

Cytokeratin 19 (CK19) is an acidic protein of 40 kDa that is part of the cytoskeleton of epithelial cells. It is highly expressed by all epithelial cells and represents a useful indicator of epithelial differentiation. The soluble fragment of CK19 (CYFRA 21–1) can be a useful circulating tumor marker and can be detected in the serum of cancer patients. The development of metastasis in patients with cancer of epithelial origin is due to the migration of tumor cells from the original tumor to distant organs. In order to detect micrometastasis in patients with breast cancer, we evaluated and compared CK19 gene expression using RT-PCR in blood samples collected from 80 healthy women and 80 patients with localized or metastatic breast cancer. The concentration of the soluble CK19 fragment CYFRA 21–1 was measured in serum of all study subjects by radioimmunoassay employing specific monoclonal antibodies. The relationship between the expression of this molecular marker and clinical stage, tumor differentiation and CK19 mRNA transcripts was investigated. We found that CK19 mRNA expression in blood (as a direct index of the presence of circulating tumor cells) was not correlated with CYFRA 21–1.

Metaplastic breast carcinoma development following surgical resection of an inflammatory myofibroblastic tumor in the right breast: A case report

Inflammatory myofibroblastic tumors (IMTs) are uncommon, mesenchymal lesions, and malignant transformation is extremely rare. The current study presents the case of a 56-year-old female with a rapidly growing mass in the right breast, which was diagnosed as IMT. Immunohistochemically, the mass was positive for smooth muscle actin (SMA) and Ki-67 (positive staining in 30% of the cells), and negative for S-100, cluster of differentiation (CD)34, p63 and cytokeratin. Malignant transformation to metaplastic carcinoma of the spindle-cell type was observed following surgical resection. This metaplastic carcinoma demonstrated positive immunoreactivity for cytokeratin, vimentin, CD34, p63 and Ki-67 (>30%), and was negative for cytokeratin 7, SMA, desmin and S-100. The patient underwent total mastectomy of the right breast, followed by palliative chemotherapy with capecitabine; however, the patient succumbed to the disease after 12 weeks. The unusual case presented in the current study emphasizes the importance of pre-operative examinations to determine the benign or malignant nature of IMTs, which aids in the choice of appropriate surgical procedures.

Cytokeratin19-2g2, a novel fragment of cytokeratin19 in serum, indicating a more invasive behavior and worse prognosis in breast cancer patients

Background

Various studies have been searching for new tumor biomarkers for breast cancer for years. However, so far, few markers have been proved clinically useful except CA153. Based on knowledge that most adenocarcinomas including breast carcinoma expressed Cytokeratin19, the authors studied CK19-2G2,a novel fragment of cytokeratin19 shedding into serum in breast cancer patients.

Patients and Methods

The serum samples of four hundred and seventeen patients including three hundred and three (fifty-four DCIS and two hundred and forty-nine stage I-III) PBC patients and one hundred and fourteen MBC patients, eighty-one healthy controls and twenty-one breast benign disease patients were provided for measurement of CK19-2G2, CEA and CA153.The correlation between clinicopathological characters, prognosis and CK19-2G2 levels was further studied.

Results

The serum CK19-2G2 levels in breast cancer patients were significantly higher than that in healthy and benign controls. For breast cancer patients, CK19-2G2 levels in MBC were significantly higher than that in PBC patients. The sensitivities of CK19-2G2 for breast carcinoma are as high as CEA and CA153, and up to 71% in MBC patients. Serum CK19-2G2 levels (≥2 mU/mL) were associated with pathological stages, tumor size (≥2 cm), lymph node involvement, and HER2 status. Multivariate analysis revealed that high serum CK19-2G2 level was an independent factor for relapse (P = 0.029) and death (P = 0.040) in breast cancer patients.

Conclusion

Serum CK19-2G2 may be an independent indicator for prognosis and a candidate marker for monitoring metastasis in breast cancer.

Gene regulation by SMAR1: Role in cellular homeostasis and cancer

Changes in the composition of nuclear matrix associated proteins contribute to alterations in nuclear structure, one of the major phenotypes of malignant cancer cells. The malignancy-induced changes in this structure lead to alterations in chromatin folding, the fidelity of genome replication and gene expression programs. The nuclear matrix forms a scaffold upon which the chromatin is organized into periodic loop domains called matrix attachment regions (MAR) by binding to various MAR binding proteins (MARBPs). Aberrant expression of MARBPs modulates the chromatin organization and disrupt transcriptional network that leads to oncogenesis. Dysregulation of nuclear matrix associated MARBPs has been reported in different types of cancers. Some of these proteins have tumor specific expression and are therefore considered as promising diagnostic or prognostic markers in few cancers. SMAR1 (scaffold/matrix attachment region binding protein 1), is one such nuclear matrix associated protein whose expression is drastically reduced in higher grades of breast cancer. SMAR1 gene is located on human chromosome 16q24.3 locus, the loss of heterozygosity (LOH) of which has been reported in several types of cancers. This review elaborates on the multiple roles of nuclear matrix associated protein SMAR1 in regulating various cellular target genes involved in cell growth, apoptosis and tumorigenesis.

Placental growth factor (PlGF) enhances breast cancer cell motility by mobilising ERK1/2 phosphorylation and cytoskeletal rearrangement

Background:

During metastasis, cancer cells migrate away from the primary tumour and invade the circulatory system and distal tissues. The stimulatory effect of growth factors has been implicated in the migration process. Placental growth factor (PlGF), expressed by 30–50% of primary breast cancers, stimulates measurable breast cancer cell motility in vitro within 3 h. This implies that PlGF activates intracellular signalling kinases and cytoskeletal remodelling necessary for cellular migration. The PlGF-mediated motility is prevented by an Flt-1-antagonising peptide, BP-1, and anti-PlGF antibody. The purpose of this study was to determine the intracellular effects of PlGF and the inhibiting peptide, BP-1.

Methods:

Anti-PlGF receptor (anti-Flt-1) antibody and inhibitors of intracellular kinases were used for analysis of PlGF-delivered intracellular signals that result in motility. The effects of PlGF and BP-1 on kinase activation, intermediate filament (IF) protein stability, and the actin cytoskeleton were determined by immunohistochemistry, cellular migration assays, and immunoblots.

Results:

Placental growth factor stimulated phosphorylation of extracellular-regulated kinase (ERK)1/2 (pERK) in breast cancer cell lines that also increased motility. In the presence of PlGF, BP-1 decreased cellular motility, reversed ERK1/2 phosphorylation, and decreased nuclear and peripheral pERK1/2. ERK1/2 kinases are associated with rearrangements of the actin and IF components of the cellular cytoskeleton. The PlGF caused rearrangements of the actin cytoskeleton, which were blocked by BP-1. The PlGF also stabilised cytokeratin 19 and vimentin expression in MDA-MB-231 human breast cancer cells in the absence of de novo transcription and translation.

Conclusions:

The PlGF activates ERK1/2 kinases, which are associated with cellular motility, in breast cancer cells. Several of these activating events are blocked by BP-1, which may explain its anti-tumour activity.

Cancer Biomarker Discovery via Targeted Profiling of Multiclass Tumor Tissue-Derived Proteomes

Introduction

Tumor-derived proteins and naturally occurring peptides represent a rich source of potential cancer markers for multiclass cancer distinction.

Materials and Methods

In this study, proteomes/peptidomes derived from primary colon cancer, kidney cancer, liver cancer, and glioblastoma were analyzed by liquid chromatography coupled with mass spectrometry to identify multiclass cancer discriminative protein and peptide candidates. Spectral counting and peptidomic analyses found two biomarker panels, one with 12 proteins and the other with 53 peptides, both capable of multiclass cancer detection and classification.

Results and Discussion

Shed from tumor tissues through apoptosis/necrosis, cell secretion, or tumor-specific degradation of extracellular matrix proteins, these proteins/peptides are likely to enter into circulation and, therefore, have the potential to be configured into practical serological diagnostic and prognostic utilities.

Mouse mammary tumor virus p75 and p110 CUX1 transgenic mice develop mammary tumors of various histologic types

The p75 and p110 isoforms of the CUX1 homeodomain protein are overexpressed in breast tumors and cancer cell lines. To assess and compare the ability of these short CUX1 isoforms in driving mammary tumor development, we used site-specific transgenesis into the Hprt locus to generate transgenic mice expressing p75 or p110 CUX1 under the control of the mouse mammary tumor virus-long terminal repeat. We report that mammary tumors developed after a long latency period, and although various histopathologies were observed, the proportion of adenosquamous carcinomas was significantly higher in p75 CUX1 than in p110 CUX1 transgenic mice. Metastasis to the lung was observed in three p75 CUX1 transgenic mice. Comparisons between tumors and adjacent normal mammary glands revealed that transgenes were overexpressed in most but not all tumors, yet in all cases tested, CUX1 DNA binding was increased, suggesting that both higher expression and changes in post-translational modifications can contribute to stimulate transgene activity. Interestingly, higher expression of erbB2 mRNA was seen in most tumors, not only solid carcinomas but also adenosquamous carcinomas, whereas higher expression of various Wnt genes and activation of the beta-catenin pathway was observed primarily in adenosquamous carcinomas. Activation of erbB2 expression appeared to represent a cooperating event that occurred independently of CUX1. In contrast, chromatin immunoprecipitation, short hairpin RNA-mediated knockdown, and reporter assays established that CUX1 is involved in the transcriptional regulation of several Wnt genes. Together, these results support the notion that oncogenic activity of CUX1 can facilitate the establishment of a Wnt/beta-catenin autocrine loop.

Tumor suppressor SMAR1 downregulates Cytokeratin 8 expression by displacing p53 from its cognate site

Intermediary filaments play a crucial role in transformation of cells to a malignant phenotype. Here, we report that tumor suppressor SMAR1 downregulates Cytokeratin 8 gene expression by modulating p53-mediated transactivation of this gene. Moreover, the cell surface cytokeratin expression was downregulated leading to a decreased migration and invasiveness of cells. We further validated these results using genotoxic stress agents that lead to an increase in the levels of SMAR1 protein. This subsequently represses the transcription of Cytokeratin 8 gene by local chromatin condensation mediated by histone methylation and deacetylation. Evaluation of SMAR1 and Cytokeratin 8 proteins in different grades of cancer using tissue microarray point out at the inverse expression profiles of these genes (i.e. low levels of SMAR1 correlating with high expression of Cytokeratin 8) in higher grades of breast cancer. Therefore, the results presented here highlight the mechanism of Cytokeratin 8 gene regulation by interplay of tumor suppressor proteins SMAR1 and p53.

Co-expression of cytokeratin 8 and breast cancer resistant protein indicates a multifactorial drug-resistant phenotype in human breast cancer cell line

AIMS

The aim was to determine whether increased CK8 and BCRP expression cooperatively contribute to multidrug resistance (MDR) in MCF-7/MX cells. Accumulating evidence suggests that the development and maintenance of cancer MDR involves complex multimodal mechanisms that interact concomitantly and complementarily. In this report, we observed elevated expression of cytokeratin 8 (CK8) in MCF-7/MX, a mitoxantrone (MX)-selected human breast tumor cell line with the MDR phenotype known as overexpression of breast cancer resistant protein (BCRP).

MAIN METHODS

Gene transfection methods were used to express CK8 and BCRP in NIH3T3 fibroblasts, individually or in combination.

KEY FINDINGS

Taken together, our present study suggests that CK8 together with BCRP may play significant roles in conferring the multifactorial MDR phenotype of MCF-7/MX cells, but may act independently via potentially different mechanisms. Although expressing either CK8 or BCRP alone was able to confer resistance to mitoxantrone, cells co-expressing both proteins demonstrated significantly increased drug resistance. Furthermore, RNAi knockdown of CK8 and BCRP, alone and in combination, in MCF-7/MX cells significantly attenuated their resistance to chemotherapeutic agents. Interestingly, in contrast to inhibition of BCRP expression via anti-BCRP shRNA vector transfection, reversal of mitoxantrone resistance by transfection with anti-CK8 shRNA was not accompanied by an increase in intracellular drug accumulation.

SIGNIFICANCE

Combinational approaches that target multiple drug-resistance-related molecules/pathways in cancer cells may represent more efficacious strategies to overcome MDR.

Estrogen receptor-negative breast carcinomas: a review of morphology and immunophenotypical analysis

Estrogen receptor (ER)-negative breast cancers are a group of tumors with poor prognosis and fewer cancer prevention and treatment strategies compared to ER-positive tumors. The aim of this study was to assess the morphological characteristics and immunohistochemical profile of ER-negative tumors and thus to understand the biological behavior and unique nature. In total, 291 consecutive ER-negative cases available from our primary breast cancer series were examined. Hematoxylin- and eosin-stained sections of all the cases were studied for several morphological parameters and their immunophenotype profile. These findings were correlated with patient and tumor characteristics and survival data. ER-negative tumors constituted 30% of the primary operable breast cancer series. The majority of tumors were grade 3 (94%) and the commonest histological types were ductal/no specific type (85%), and atypical medullary carcinoma (8%). High-grade comedo-type necrosis, lymphoid stroma, central necrosis/fibrosis and pushing margins were the most common morphological features. The presence of a pushing margin showed a significant relation to androgen receptor negativity, absence of epidermal growth factor receptor expression and negative lymph nodes. Lymphoid stroma and comedo-necrosis correlated with higher tumor grade. ER-negative breast cancers are a distinct group of tumors with several common morphological features. Grade 3 histology, pushing margin, lymphoid stroma, comedo-type necrosis and central fibrosis/necrosis are the dominant morphological findings. The presence of a pushing margin appears to have a significant correlation with negative lymph node status. ER-negative tumors show a higher expression of p53, CerbB2 and epidermal growth factor receptor compared to ER-positive breast cancer. These unique features support the concept that ER-negative tumors are a morphologically and phenotypically distinct entity and provide a rationale for the study and use of newer promising agents in the treatment of ER-negative breast cancer.

Development of the human breast

The human breast undergoes a complete series of changes from intrauterine life to senescence. These changes can be divided into two distinct phases; the developmental phase and the differentiation phase. The developmental phase includes the early stages of gland morphogenesis, from nipple epithelium to lobule formation. In lobule formation, both processes, development and differentiation, take place almost simultaneously. For example, the progressive transition of lobule type 1 to types 2, 3, and 4 requires active cell proliferation, to acquire the cell mass necessary for the function of milk secretion. This later process implies differentiation of the mammary epithelium. Therefore, the presence of lobule type 4 is the maximal expression of development and differentiation in the adult gland, whereas the presence of lobule type 3 could indicate that the gland has already been developed. It is important to point out that the presence of proteins that are indicative of milk secretion, such as alpha-lactalbumin, casein, or milk fat lobule type membrane protein, also indicates cellular differentiation of breast epithelium. However, only when all the other components of milk, (such as lactose, alpha-lactalbumin, casein and milk fat) are coordinately synthesized within the appropriate structure can full differentiation of the mammary gland be acknowledged.

Serum CYFRA 21-1 (cytokeratin-19 fragments) is a useful tumour marker for detecting disease relapse and assessing treatment efficacy in breast cancer

The usefulness of serum CYFRA 21-1 (cytokeratin-19 fragments) in monitoring the recurrence of breast cancer and in evaluating therapeutic effects was studied retrospectively. The sera from 173 patients with primary breast cancer or recurrent disease were measured for CYFRA 21-1, carcinoembryonic antigen (CEA), and carbohydrate antigen 15-3 (CA 15-3) levels. The positive rates of serum CYFRA 21-1 for stage IV (n=12) or recurrent disease (n=26) were 83.3 and 84.6%, respectively, while those of serum CEA were 41.7 and 26.9%, and those of serum CA 15-3 were 83.3 and 34.6%. The elevated preoperative levels of serum CYFRA 21-1 decreased to normal levels after curative operation, whereas the levels remained abnormally high after noncurative operation. There was a significantly high frequency of recurrence in patients with elevated levels of serum CYFRA 21-1 preoperatively compared to those with normal levels of the marker preoperatively. The serum CYFRA 21-1 levels were well correlated with response to chemotherapy. The positive rate of serum CYFRA 21-1 alone was higher than that of an assay combining CEA with CA 15-3, in both primary and recurrent cases (28.8 vs 18.8 and 84.6 vs 46.2%, respectively). These observations suggest that serum CYFRA 21-1 may be a reliable marker of recurrence or therapeutic efficacy.

Polyomavirus middle T–induced mammary intraepithelial neoplasia outgrowths: Single origin, divergent evolution, and multiple outcomes

The development of models to investigate the pathobiology of premalignant breast lesions is a critical prerequisite for development of breast cancer prevention and early intervention strategies. Using tissue transplantation techniques, we modified the widely used polyomavirus middle T (PyV-mT) transgenic mouse model of breast cancer to study the premalignant stages of tumorigenesis. Premalignant atypical lesions were isolated from PyV-mT transgenic mice and used to generate two sets of three mammary intraepithelial neoplasia (MIN) outgrowth lines. Investigation of these six unique lines, each of which fulfills the criteria for MIN, has provided new information regarding the biology of PyV-mT-induced neoplasia. Although expression of the PyV-mT transgene was the primary initiating event for all lines, they exhibited different tumor latencies, metastatic potentials, and morphologies. Six distinguishable morphologic patterns of differentiation were identified within the premalignant outgrowths that are likely to represent several tumorigenic pathways. Further, several tumor phenotypes developed from each line and the tumors developing from the six lines had different metastatic potentials. These observations are consistent with the hypothesis that distinct pathways of PyV-mT-initiated neoplastic progression lead to different outcomes with respect to latency and metastasis. The MIN outgrowth lines share several characteristics with precursors of human breast cancer including the observation that gene expression profiles of tumors are more similar to those of the MIN outgrowth line outgrowth from which they developed than to other tumors. These lines provide an opportunity to study the full range of events occurring secondary to PyV-mT expression in the mammary gland.

Enrichment methods to detect bone marrow micrometastases in breast carcinoma patients: clinical relevance

Introduction

Improving technologies for the detection and purification of bone marrow (BM) micrometastatic cells in breast cancer patients should lead to earlier prognosis of the risk of relapse and should make it possible to design more appropriate therapies. The technique used has to overcome the challenges resulting from the small number of target cells (one per million hematopoietic cells) and the heterogeneous expression of micrometastatic cell markers. In the present study, we have assessed the clinical relevance of current methods aimed at detecting rare disseminated carcinoma cells.

Methods

BM aspirates from 32 carcinoma patients were screened for the presence of micrometastatic cells positive for epithelial cell adhesion molecule and positive for cytokeratins, using optimized immunodetection methods. A comparison with data obtained for 46 control BM aspirates and a correlation with the clinical status of patients were performed.

Results

We developed a sensitive and efficient immunomagnetic protocol for the enrichment of BM micrometastases. This method was used to divide 32 breast carcinoma patients into three categories according to their epithelial cell adhesion molecule status. These categories were highly correlated with the recently revised American Joint Committee on Cancer staging system for breast cancer, demonstrating the clinical relevance of this simple and reliable immunomagnetic technique. We also evaluated immunocytochemical detection of cytokeratin-positive cells and cytomorphological parameters. Immunocytochemistry-based methods for the detection of BM micrometastases did not provide any information about the clinical status of patients, but helped to refine the immunomagnetic data by confirming the presence of micrometastases in some cases. We also tested a new density gradient centrifugation system, able to enrich the tumor fraction of BM specimens by twofold to threefold as compared with standard Ficoll methods.

Conclusion

These improved methods for the detection of micrometastatic cells in patient BM should help clinicians to predict the clinical status of breast cancer patients at the time of surgery or treatment.

Identification of differentially expressed genes in isogenic highly metastatic and poorly metastatic cell lines of R3230AC rat mammary adenocarcinoma

Tumour metastasis occurs as a result of a cascade of events including alterations in the expression of various genes. The identification of such genes is essential to understanding formation of metastasis. In a previous study, highly metastatic (LN4.D6) and poorly metastatic (CAb.D5) cell lines were obtained from the rat mammary adenocarcinoma cell line R3230AC. Subtractive hybridization was used to identify differentially expressed genes between these two cell lines. We identified eight cDNA clones in CAb.D5 and six cDNA clones in LN4.D6 that were differentially expressed. One of the cDNA clones in each cell line had no homology with known sequences. Expression patterns of these differentially expressed genes were examined in a pair of rat mammary and prostate adenocarcinoma cell lines. Compared with cell lines examined, cDNA FF-10 was only expressed in CAb.D5; however, cDNA RB-8, RE-1, RF-5 were only expressed in the highly metastatic LN4.D6. No correlation was observed between expression patterns of the differentially expressed genes and metastatic potential of these cells. However, differential expression of genes, especially cytokeratins (CK8 and CK5) and collagens (III and IV) between highly metastatic and low metastatic rat mammary adenocarcinoma cell lines might initiate further investigation of these genes in metastatic process.

Prognostic Value of Cytokeratin 19 Fragment (CYFRA 21–1) and Cytokeratin-Positive Cells in Bone Marrow Samples of Breast Cancer Patients

The aim of this study was to investigate the relationship between the detection of micrometastatic cells by immunocytochemistry (ICC) with an anticytokeratin antibody and cytokeratin fragment (CYFRA 21–1) expression detected by an immunofluorescent assay in bone marrow of breast cancer patients. Micrometastatic CK+ cells were screened with a pancytokeratin antibody A45 B/B3 from bone marrow aspiration samples of 102 breast cancer patients (65 primary tumors, 10 local recurrences and 27 distant metastases). CYFRA 21-1 levels were assessed in bone marrow supernatant of these patients before collection of the mononucleated interface cells on a Ficoll-Hypaque density gradient and in 20 control patients. CYFRA 21-1 and CK+ cell detection by ICC were both correlated with clinical stage. CYFRA 21-1 was significantly elevated in patients with micrometastatic disease detected by ICC: 4.77 ng/mL (± 10.87 SD) versus 1.00 ng/mL (± 1.36 SD) in patients with negative ICC (p=0.01). In univariate analysis, a CYFRA 21-1 value ≥1 ng/mL and the presence of CK+ cells were associated with a poorer survival for patients with stage I to III breast cancer (n=65). On multivariate analysis, only pathological nodal status and presence of CK+ cells in bone marrow were independent prognostic factors for overall survival. In conclusion, in this series CYFRA 21-1 was correlated with detection of CK+ cells by ICC in bone marrow, but cannot replace ICC. The presence of CK+ cells in bone marrow remains a strong independent prognostic factor in primary breast cancer.

Gene expression of transforming growth factor β receptors I and II in non-small-cell lung tumors

Transforming growth factor (TGF)beta inhibits normal epithelial cell proliferation. A decreased expression of TGFbeta receptors (TbetaR) has been associated with loss of TGFbeta sensitivity and enhanced tumor progression in many types of cancer. Although lung cancer is one of the leading causes of cancer death, a comparative analysis of TbetaR mRNA and protein expression in non-small-cell (NSC) lung tumors has not been performed. Lung tumor tissues and control non-lesional lung tissues were obtained from 17 patients undergoing thoracotomy for primary NSC lung tumors in clinical stage II. Each tissue sample was studied for TbetaRI and TbetaRII mRNA and immunoreactive protein expression, using a semi-quantitative reverse transcription-PCR method, and a quantitative immunohistochemistry method, respectively. TbetaRI protein expression was higher in tumors than in controls (p=0.0005) and a similar trend was present at the mRNA level. TbetaRII protein expression was not significantly different between tumors and controls, however an intense peri-nuclear staining for TbetaRII was observed in several tumor cells. TbetaRII mRNA levels were lower in tumors than in controls (p=0.005) and an inverse relation between TbetaRII mRNA and protein expression was detected in tumors (p=0.0013). Our findings suggest an altered function of the TbetaR system in NSC lung cancer.

Advances in molecular labeling, high throughput imaging and machine intelligence portend powerful functional cellular biochemistry tools

Cellular behavior is complex. Successfully understanding systems at ever-increasing complexity is fundamental to advances in modern science and unraveling the functional details of cellular behavior is no exception. We present a collection of prospectives to provide a glimpse of the techniques that will aid in collecting, managing and utilizing information on complex cellular processes via molecular imaging tools. These include: 1) visualizing intracellular protein activity with fluorescent markers, 2) high throughput (and automated) imaging of multilabeled cells in statistically significant numbers, and 3) machine intelligence to analyze subcellular image localization and pattern. Although not addressed here, the importance of combining cell-image-based information with detailed molecular structure and ligand-receptor binding models cannot be overlooked. Advanced molecular imaging techniques have the potential to impact cellular diagnostics for cancer screening, clinical correlations of tissue molecular patterns for cancer biology, and cellular molecular interactions for accelerating drug discovery. The goal of finally understanding all cellular components and behaviors will be achieved by advances in both instrumentation engineering (software and hardware) and molecular biochemistry.

Strong feature sets from small samples

For small samples, classifier design algorithms typically suffer from overfitting. Given a set of features, a classifier must be designed and its error estimated. For small samples, an error estimator may be unbiased but, owing to a large variance, often give very optimistic estimates. This paper proposes mitigating the small-sample problem by designing classifiers from a probability distribution resulting from spreading the mass of the sample points to make classification more difficult, while maintaining sample geometry. The algorithm is parameterized by the variance of the spreading distribution. By increasing the spread, the algorithm finds gene sets whose classification accuracy remains strong relative to greater spreading of the sample. The error gives a measure of the strength of the feature set as a function of the spread. The algorithm yields feature sets that can distinguish the two classes, not only for the sample data, but for distributions spread beyond the sample data. For linear classifiers, the topic of the present paper, the classifiers are derived analytically from the model, thereby providing an enormous savings in computation time. The algorithm is applied to cancer classification via cDNA microarrays. In particular, the genes BRCA1 and BRCA2 are associated with a hereditary disposition to breast cancer, and the algorithm is used to find gene sets whose expressions can be used to classify BRCA1 and BRCA2 tumors.

Serum cytokeratin fragment 21.1 (CYFRA 21.1) as tumour marker for breast cancer: comparison with carbohydrate antigen 15.3 (CA 15.3) and carcinoembryonic antigen (CEA)

Serum carbohydrate antigen 15.3 (CA 15.3) and carcinoembryonic antigen (CEA) are currently employed in clinical practice as markers for breast cancer, particularly in the follow-up and therapy monitoring. However, the American Society for Clinical Oncology (ASCO) stated in its clinical practice guidelines for the use of tumour markers in breast carcinoma that neither CA 15.3 nor CEA are recommended for routine use in screening, diagnosis and surveillance after primary treatment, or in monitoring response to treatment, because current literature data are insufficient. Cytokeratin fragment 21.1 (CYFRA 21.1) assay detects a serum fragment of cytokeratin 19 (CK19) and is employed in the diagnosis and management of lung cancer, particularly of squamous cell histotype. Breast carcinoma has been demonstrated to express CK19 fragments in the primary and metastatic lesions and CK19 mRNA is detectable in peripheral blood from patients affected by breast cancer. We measured serum markers CYFRA 21.1, CEA and CA 15.3 in the sera from 212 females affected by histologically proven breast carcinoma. Patients comprised 96 individuals with untreated primary disease (54 stage I-II, 18 stage III and 24 stage IV), 30 regional (chest-wall and/or lymph-nodes) relapsing disease and 68 metastatic (haematogenous metastases) relapsing disease. Forty-eight patients previously treated by surgery and without any evidence of disease were enrolled to evaluate the role of serum markers in the monitoring for recurrence of the disease. One hundred healthy age-matched females and 65 patients affected by benign mammary gland disease (including 38 patients with mastopathy and 27 with fibroadenoma) were enrolled as controls. Serum levels of all markers increased from controls to patients affected by breast cancer, from stage I-II to stage IV of the breast cancer and from local to advanced recurrence. The comparison of diagnostic accuracy in the detection of primary and relapsing breast cancer showed no significant differences between markers. Univariate and multivariate survival analysis showed a significant statistically prognostic value for CA 15.3 and CYFRA 21.1 but not for CEA. However, the factors N and M were confirmed to be very strong predictors of the patients' survival. Finally, CEA and CYFRA 21.1 detected less recurrences than CA 15.3. In conclusion, our data show no significant improvement in the diagnosis, prognostic evaluationand follow-up of breast cancer by CYFRA 21.1 and CEA assays compared to CA 15.3 assay. Considering the ASCO statement on tumour markers in breast cancer, the CYFRA 21.1 assay should not be employed in clinical practice.

Identification of estrogen-induced genes downregulated by AhR agonists in MCF-7 breast cancer cells using suppression subtractive hybridization

Aryl hydrocarbon receptor (AhR) agonists inhibit 17beta-estradiol (E2) induced growth of MCF-7 human breast cancer cells in vitro and rodent mammary tumor growth in vivo. Genes associated with inhibitory AhR-estrogen receptor (ER) crosstalk were investigated in MCF-7 human breast cancer cells using poly(A)(+)RNA from cells treated with either 1 nM E2 (target) or E2 plus 1 nM 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) (reference) or 25 microM diindolylmethane (DIM) as AhR agonists in MCF-7 cells. Suppression subtractive hybridization (SSH) was subsequently used to identify 33 genes with sequence homology to known human genes that are induced by E2 and inhibited by AhR agonists in MCF-7 cells; two unknown genes were also identified. Many of these genes are involved in cell proliferation and these include cell cycle regulators (cdc28/cdc2-associated protein), nucleotide synthases (thymidylate synthase), early intermediate genes (early growth response alpha, EGRalpha) and other proteins involved in signaling pathways (calmodulin, ATP synthase alpha subunit). Thus SSH has identified a diverse spectrum of new genes that are affected by inhibitory AhR-ER crosstalk and among this group are a subset of genes that may be critical for the in vivo antitumorigenic effects of AhR agonists.

Serum CYFRA 21-1 is one of the most reliable tumor markers for breast carcinoma

BACKGROUND

The search for new tumor markers for breast carcinoma has been an area of vigorous study; nonetheless, to the authors' knowledge little new information has emerged beyond the clinical usefulness of CA 15-3. The authors studied serum CYFRA 21-1 in breast carcinoma based on evidence that breast carcinoma expresses cytokeratin 19 fragments and that CYFRA 21-1 is a specific antigen for cytokeratin 19 fragments.

METHODS

The serum samples of 86 patients with primary breast carcinoma, 14 patients with recurrent breast carcinoma, 22 patients with benign mammary disease, and 25 healthy controls were provided for measurements of CYFRA 21-1, carcinoembryonic antigen (CEA), and CA 15-3. The relation between clinicopathologic features, prognosis, and disease free survival with serum CYFRA 21-1 titers was studied.

RESULTS

There was no difference between the serum CYFRA 21-1 titers from patients with benign mammary disease and those from healthy controls. The sensitivities of CYFRA 21-1 for patients with International Union Against Cancer Stage IV and recurrent tumors were 60% and 64.2%, respectively, which were as high as those for CA 15-3 and superior to those for CEA. The hematogenous recurrence showed a very high sensitivity of 89%. According to the increments of T, N, and M factor numbers, the serum CYFRA 21-1 titers were elevated. No correlation between CYFRA 21-1 and CEA was observed and the correlation between CYFRA 21-1 and CA 15-3 was weak. The univariate and multivariate analyses for survival revealed that serum CYFRA 21-1 levels were an independent indicator of prognosis.

CONCLUSIONS

The measurement of the serum CYFRA 21-1 titer in patients with breast carcinoma may be useful in monitoring for recurrence and evaluating the therapeutic effect in patients with advanced disease.

Proteomic definition of normal human luminal and myoepithelial breast cells purified from reduction mammoplasties

Normal human luminal and myoepithelial breast cells separately purified from a set of 10 reduction mammoplasties by using a double antibody magnetic affinity cell sorting and Dynabead immunomagnetic technique were used in two-dimensional gel proteome studies. A total of 43,302 proteins were detected across the 20 samples, and a master image for each cell type comprising a total of 1,738 unique proteins was derived. Differential analysis identified 170 proteins that were elevated 2-fold or more between the two breast cell types, and 51 of these were annotated by tandem mass spectrometry. Muscle-specific enzyme isoforms and contractile intermediate filaments including tropomyosin and smooth muscle (SM22) alpha protein were detected in the myoepithelial cells, and a large number of cytokeratin subclasses and isoforms characteristic of luminal cells were detected in this cell type. A further 134 nondifferentially regulated proteins were also annotated from the two breast cell types, making this the most extensive study to date of the protein expression map of the normal human breast and the basis for future studies of purified breast cancer cells.