Bone marrow mammaglobin-1 (SCGB2A2) immunohistochemistry expression as a breast cancer specific marker for early detection of bone marrow micrometastases.

Despite all the advances in the management of breast cancer (BC), patients with distance metastasis are still considered incurable with poor prognosis. For that reason, early detection of the metastatic lesions is crucial to improve patients' life span as well as quality of life. Many markers were proposed to be used as biomarkers for metastatic BC lesions, however many of them lack organ specificity. This highlights the need for novel markers that are more specific in detecting disseminated BC lesions. Here, we investigated mammaglobin-1 expression as a potential and specific marker for metastatic BC lesions using our patient cohort consisting of 30 newly diagnosed BC patients. For all patients, bone marrow (BM) aspiration, BM biopsy stained by H&E and BM immunohistochemically stained for mammaglobin-1 were performed. In addition, the CA15-3 in both serum and bone marrow plasma was also evaluated for each patient. Indeed, mammaglobin-1 immuno-staining was able to detect BM micrometastases in 16/30 patients (53.3%) compared to only 5/30 patients (16.7%) in BM biopsy stained by H&E and no cases detected by BM aspirate (0%). In addition, our results showed a trend of association between mammaglobin-1 immunoreactivity and the serum and BM plasma CA15-3. Further validation was done using large publicly available databases. Our results showed that mammaglobin-1 gene expression to be specifically upregulated in BC patients' samples compared to normal tissue as well as samples from other cancers. Moreover, our findings also showed mammaglobin-1 expression to be a marker of tumour progression presented as lymph nodes involvement and distant metastasis. These results provide an initial evidence for the use of mammaglobin-1 (SCGB2A2) immunostaining in bone marrow as a tool to investigate early BM micrometastases in breast cancer.

Identification and characterization of mammaglobin-A epitope in heterogenous breast cancers for enhancing tumor-targeting therapy.

Although targeted therapy has been extensively investigated for breast cancers, a molecular target with broad application is currently unavailable due to the high heterogeneity of these cancers. Mammaglobin-A (Mam-A), which is overexpressed in most breast carcinomas, has been proposed as a promising target. However, the lack of specific targeting moieties due to uncertain binding epitopes hampers further translational study. Here, seven potential epitopes of Mam-A were disclosed, and a unique epitope was then identified in most types of breast cancers, despite the genotypic heterogeneity. With phage display technology, the epitope was determined to be N-terminal amino acids 42-51 of Mam-A (N42-51). Then, the N42-51 epitope-specific monoclonal antibody, mAb785, was conjugated to poly lactic-co-glycolic acid (PLGA) nanoparticles loaded with therapeutic agents, thereby enhancing the drug uptake and therapeutic efficacy in different genotypes of breast cancers. The computer simulation of the N42-51 epitope and the mAb785 structures, as well as their interactions, further revealed the specific targeting mechanism of the mAb785-conjugated nanoparticles to breast cancers.

Detection of gene expression in sentinel lymph node of primary breast cancer patients.

Sentinel lymph node (SLN) micrometstasis detection improves outcome for breast cancer follow up procedure. The aim of the present study was to identify gene profiles that accurately predicted the outcome of breast cancer patients. Fifty tumor sample from breast cancer patients were analyzed for the expression of 3 genes using quantitative-PCR. Also clinical verification for recurrence to distant organs was performed. Three gene signature were confirmed based on tumor's stage, grade, ER status, using conditional logistic regression. Based on this findings, the negative reported lymph nodes for metastasis, had micro metastasis in significant values. There was a significant difference between normal and cancer samples in 3 gene expression marker and also there was meaningful relationship between three gene expression with tumor's grade, stage according to progression of tumor. A novel gene expression signature predictive of micro metastatic patients was evaluated. In this assessment, relationship between this gene with tumor's features   that finding clear role for these genes with tumor's outcome, needs to be established.

GATA-3 is superior to GCDFP-15 and mammaglobin to identify primary and metastatic breast cancer.

PURPOSE: Despite numerous studies on the utility of GATA-3 as breast cancer marker, its comparison with other breast markers, its concordance between primary and metastatic tumors and its expression in primary cancers from sites with frequent breast metastases remains unclear. METHODS: To address these questions, totally 993 invasive breast cancers (IBC), 254 paired nodal metastases, 23 distant metastases, and 208 lung carcinomas were included. GATA-3 expression was analyzed by immunohistochemistry and compared to other breast markers [gross cystic disease fluid protein 15 (GCDFP-15) and mammaglobin (MGB)]. RESULTS: GATA-3 was expressed in 82.5% of IBC, predominantly in luminal (93.9%), and lower in non-luminal cancers [59.6% of HER2 overexpressing (HER2-OE) and 38.1% of triple negative breast cancer (TNBC) subtypes]. GATA-3 identified more IBC than GCDFP-15 (23.9%) and MGB (46.6%). However, MGB showed a comparable sensitivity for non-luminal cancers to GATA-3. Combining MGB and GATA-3 improved sensitivity for both HER2-OE (80.8%) and TNBC cases (55.4%). GATA-3 showed a high sensitivity for nodal metastases and distant metastases, with good concordance with primary tumors. GATA-3 was expressed in 1.0% of lung carcinomas, with sensitivity and specificity of 82.5 and 99.0% in differentiating IBC and lung carcinoma. CONCLUSIONS: GATA-3 expression was the highest in luminal breast carcinomas, and showed higher sensitivity than GCDFP-15 and MGB. However, in the poorly differentiated IBC, its utility was still limited. One should be aware of the possible GATA-3 expression in lung carcinomas.

Evaluation of the Metasin assay for intraoperative assessment of sentinel lymph node metastases in breast cancer.

AIMS: Sentinel lymph node (SLN) biopsy is the preferred surgical technique for staging the axilla in clinically node-negative breast cancer. Accurate intraoperative staging allows for the immediate performance of an axillary clearance in node-positive patients. We assessed the Metasin assay for the intraoperative analysis of SLNs in a prospective evaluation of 250 consecutive patients undergoing intraoperative SLN analysis at the Breast Unit, University Hospital, Southampton, UK. METHODS: Metasin uses a quantitative reverse transcription PCR to detect two markers of metastasis: cytokeratin 19 (CK19) an epithelial marker and mammaglobin (MGB) a breast specific marker. Metasin results were compared with the results from routine paraffin block histopathology. RESULTS: Metasin was robust, with a failure rate of <1%, and demonstrated excellent accuracy and reproducibility. The average turnaround time for the Metasin assay was 42 min, the largest variable being the number of nodes assayed. A total of 533 SLNs were evaluated with 75 patients testing positive for MGB and/or CK19. Based on the analysis of individual SLNs, the overall concordance between Metasin and histology was 92.3% (sensitivity 88.7%, specificity 92.9%). When adjusted for tissue allocation bias, the concordance was 93.8% (sensitivity 89.8%, specificity 94.6%). In this evaluation, 57/250 patients (23%) proceeded to axillary clearance based on Metasin results and were considered spared a second operative procedure. CONCLUSIONS: Metasin has proven to be an accurate, reproducible and reliable laboratory test. The analysis time is acceptable for intraoperative use, and in comparison to routine histology demonstrates acceptable concordance, sensitivity and specificity.

[Mammaglobin in peripheral blood and tumor in breast cancer patients]. / Mammaglobin v perifericheskoi krovi i opukholi pri rake molochnoi zhelezy.

Currently, no molecular biological markers do exist for early diagnosis of breast cancer. One of the possible candidates for the marker of early breast cancer is mammaglobin (MGB1) or SCGB2A2 (secretoglobin, family 2A, member 2), characterized by the maximal expression level in early breast cancer. Using the RT-PCR method MGB1 mRNA expression was examined in 57 tumor tissue samples and 57 samples of morphologically non-malignant tissue (MNT) of breast cancer (BC) patients. Specificity and sensitivity of the MGB1 mRNA assay in peripheral blood of BC patients was evaluated by nested PCR. 169 blood samples (from 95 BC patients, 22 from patients with benign breast tumors, 28 from patients with tumors of other localizations, and 24 samples from healthy donors) have been analyzed. MGB1 expression was significantly higher in BC tissue samples compared to MNT (p=0.0019). The maximal expression level was in the samples T1 (p=0.013), stage I BC (p=0.037), GI (p=0.0019). The MGB1 expression positively correlated with expression of estrogen (p = 0,034) and progesterone (p=0.0004) receptors. Sensitivity and specificity of the MGB1 mRNA assay in peripheral blood were 60.6% and 92.3%, respectively. Expression of MGB1 was higher in BC than MNT and it decreased during BC progression. The sensitivity and specificity of the MGB1 mRNA assay may be used as an additional diagnostic method.

Human mammaglobin: A specific marker for breast cancer prognosis.

PURPOSE: In this study, we examined the expression of human mammaglobin (hMAM) mRNA and the protein levels in patients with breast cancer and their relationship with prognostic clinicopathological parameters. METHODS: hMAM mRNA expression in leucocytes from peripheral blood samples from patients diagnosed with primary invasive breast cancer (IC), carcinoma in situ (CIS), or benign breast diseases was analyzed using RT-PCR. The hMAM protein levels and expression patterns in tissue from 3 patient groups were evaluated by immunohistochemical staining, and several non-breast neoplasms were selected as negative controls, undergoing the same examination. RESULTS: The expression of hMAM mRNA was significantly higher in patients with IC or CIS compared to those with benign tumors (both<0.01). Immunohistochemical staining revealed similar results, where patients with IC or CIS had higher levels of hMAM protein (p<0.01 and p<0.01, respectively), while none of the negative controls expressed hMAM. Further analyses showed a strong correlation between hMAM protein/mRNA expression and clinicopathological factors, such as histological grade, clinical stage, and lymph node status, in patients with IC. CONCLUSION: The hMAM mRNA and protein expression profiles validate the potential of hMAM as a specific marker for breast cancer diagnosis and target treatment delivery.

Mammaglobin 1 promotes breast cancer malignancy and confers sensitivity to anticancer drugs.

Mammaglobin 1 (MGB1), a member of the secretoglobin family, is expressed in mammary epithelial tissues and is overexpressed in most mammary carcinomas. Despite the extensive research correlating MGB1 expression profiles to breast cancer pathogenesis and disease outcome, the biological significance of MGB1 in cancer processes is still unclear. We have thus set out to conduct a functional evaluation of the molecular and cellular roles of MGB1 in breast cancer processes leading to disease progression. Using a series of breast cancer cell models with conditional MGB1 expression, we demonstrate that MGB1 promotes cancer cell malignant features. More specifically, loss of MGB1 expression resulted in a decrease of cell proliferation, soft agar spheroid formation, migration, and invasion capacities of breast cancer cells. Concomitantly, we also observed that MGB1 expression activates signaling pathways mediated by MAPK members (p38, JNK, and ERK), the focal adhesion kinase (FAK), matrix metalloproteinases (MMPs) and NFκB. Moreover, MGB1 regulates epithelial to mesenchymal (EMT) features and modulates Snail, Twist and ZEB1 expression levels. Interestingly, we also observed that expression of MGB1 confers breast cancer cell sensitivity to anticancer drug-induced apoptosis. Together, our results support a role for MGB1 in tumor malignancy in exchange for chemosensitivity. These findings provide one of the first descriptive overview of the molecular and cellular roles of MGB1 in breast cancer processes and may offer new insight to the development of therapeutic and prognostic strategies in breast cancer patients. © 2015 Wiley Periodicals, Inc.

Detection of human mammaglobin A mRNA in peripheral blood of breast cancer patients before treatment and association with metastasis.

BACKGROUND: Mammaglobin A (MGA), mainly expressed in the breast epithelium, is overexpressed in breast cancer, and has been established as a tumor and promissory marker for the early detection of metastasis. AIM: The main aim of this study was to evaluate the association between the presence of the MGA transcript in the peripheral blood of Brazilian breast cancer patients and healthy women and the development of breast cancer and tumor progression. MATERIAL AND METHODS: The expression of the MGA transcript in peripheral blood of 102 breast cancer patients and 102 healthy women was assessed by RT-PCR. RESULTS: MGA mRNA was expressed in the peripheral blood of 39 breast cancer patients and in none of the women from the control group. The presence of MGA was significantly associated with presence of metastasis and age at onset after 60 years. The presence of MGA mRNA in peripheral blood displayed a sensitivity of 38.2%, specificity of 100.0%, positive predictive value (PPV) of 100.0%, and negative predictive value (NPV) of 61.8% as a breast cancer marker. CONCLUSION: This study provides additional evidence of the presence of MGA in the peripheral blood of breast cancer patients, and its applicability as an efficient biomarker for breast cancer (High specificity and PPV). To our knowledge, this is the first study to assess the expression of MGA mRNA in peripheral blood obtained from the Brazilian population.

New methods to improve the safety assessment of cryopreserved ovarian tissue for fertility preservation in breast cancer patients.

OBJECTIVE: To develop a novel molecular panel of markers to detect breast cancer (BC) disseminated malignant cells in ovarian tissue, and to improve the safety of ovarian tissue transplantation. DESIGN: Experimental study. SETTING: University hospital. PATIENT(S): Ten ovarian biopsies from healthy patients, 13 biopsies with diagnosed BC metastasis, and 4 biopsies from primary BC tumor for designing a diagnostic panel of BC cell contamination; 60 ovarian biopsies from BC patients undergoing fertility preservation for validating the panel. ANIMAL(S): Female nude mice. INTERVENTION(S): A novel panel for BC malignant cell detection by reverse-transcription polymerase chain reaction (RT-PCR), inmmunohistochemical analysis, in vitro invasion assay and xenotransplantation assayed in ovarian tissue from BC patients. MAIN OUTCOME MEASURE(S): Expression of GCDFP15, MGB1, SBEM, MUC1, WT-1, and NY-BR-01, selected as markers, assessed by quantitative RT-PCR in samples with confirmed BC metastasis. The most sensitive markers were confirmed by immunohistochemistry, and tested in vitro and in vivo. RESULT(S): GCDFP15, MGB1, and SBEM were the most sensitive and specific markers to detect BC metastatic cells when at least one was expressed by quantitative RT-PCR. The panel was validated in 60 patients and confirmed in an in vitro invasion assay, where no invasive cells were observed. Samples negative for BC cells cannot develop disease when xenografted. CONCLUSION(S): GCDFP15, MGB1, and SBEM were the most sensitive molecules to create a diagnostic panel for BC malignant cell contamination, which may make ovarian tissue cryopreservation and transplantation a safe technique for fertility preservation in BC patients.

Safety and preliminary evidence of biologic efficacy of a mammaglobin-a DNA vaccine in patients with stable metastatic breast cancer.

PURPOSE: Mammaglobin-A (MAM-A) is overexpressed in 40% to 80% of primary breast cancers. We initiated a phase I clinical trial of a MAM-A DNA vaccine to evaluate its safety and biologic efficacy. EXPERIMENTAL DESIGN: Patients with breast cancer with stable metastatic disease were eligible for enrollment. Safety was monitored with clinical and laboratory assessments. The CD8 T-cell response was measured by ELISPOT, flow cytometry, and cytotoxicity assays. Progression-free survival (PFS) was described using the Kaplan-Meier product limit estimator. RESULTS: Fourteen subjects have been treated with the MAM-A DNA vaccine and no significant adverse events have been observed. Eight of 14 subjects were HLA-A2(+), and the CD8 T-cell response to vaccination was studied in detail. Flow cytometry demonstrated a significant increase in the frequency of MAM-A-specific CD8 T cells after vaccination (0.9% ± 0.5% vs. 3.8% ± 1.2%; P < 0.001), and ELISPOT analysis demonstrated an increase in the number of MAM-A-specific IFNγ-secreting T cells (41 ± 32 vs. 215 ± 67 spm; P < 0.001). Although this study was not powered to evaluate progression-free survival (PFS), preliminary evidence suggests that subjects treated with the MAM-A DNA vaccine had improved PFS compared with subjects who met all eligibility criteria, were enrolled in the trial, but were not vaccinated because of HLA phenotype. CONCLUSION: The MAM-A DNA vaccine is safe, capable of eliciting MAM-A-specific CD8 T-cell responses, and preliminary evidence suggests improved PFS. Additional studies are required to define the potential of the MAM-A DNA vaccine for breast cancer prevention and/or therapy.

Detection of circulating tumor cells in breast cancer patients using multiplex reverse transcription-polymerase chain reaction and specific primers for MGB, PTHRP and KRT19 correlation with clinicopathological features.

AIM: The aim of this study was to correlate the clinicopathological features of breast cancer patients with the positive detection of parathyroid hormone-related protein (PTHRP), cytokeratin protein 19 (KRT19) and mammaglobin (MGB) using a multiplex reverse transcription polymerase chain reaction (RT-PCR) assay developed to detect circulating tumor cells (CTCs) in peripheral blood of patients with breast cancer. PATIENTS AND METHODS: Peripheral blood samples were collected from 54 breast cancer patients and 20 healthy blood donors. Subsequently, the samples were processed for RNA extraction and analyzed for the expression of PTHRP, KRT19 and MGB using specific primers and multiplex RT-PCR. RESULTS: The positive detection rates in breast cancer patients for PTHRP, KRT19 and MGB were 68.5%, 63% and 22.2% and for healthy donors 10%, 0% and 10%, respectively. The statistical analysis revealed that PTHRP- and KRT19-positive detections correlated with the diagnosis of breast cancer while the combined positive detections of PTHRP-plus-KRT19 correlated with the presence of distant metastasis, especially with bone metastasis. Moreover, positive detections of KRT19 correlated with high proliferation rate of breast cancer tumors. MGB-positive detections did not add any diagnostic advantage in such analysis. CONCLUSION: Multiplex-PCR based detection of CTCs using PTHRP and KRT19 primers can provide useful information for the disease.

Identification and translational validation of novel mammaglobin-A CD8 T cell epitopes.

Mammaglobin-A (MAM-A) is a secretory protein that is overexpressed in 80 % of human breast cancers. Its near-universal expression in breast cancer as well as its exquisite tissue specificity makes it an attractive target for a breast cancer prevention vaccine, and we recently initiated a phase 1 clinical trial of a MAM-A DNA vaccine. Previously, we have identified multiple MAM-A CD8 T cell epitopes using a reverse immunology candidate epitope approach based on predicted binding, but to date no attempt has been made to identify epitopes using an unbiased approach. In this study, we used human T cells primed in vitro with autologous dendritic cells expressing MAM-A to systematically identify MAM-A CD8 T cell epitopes. Using this unbiased approach, we identified three novel HLA-A2-restricted MAM-A epitopes. CD8 T cells specific for these epitopes are able to recognize and lyse human breast cancer cells in a MAM-A-specific, HLA-A2-dependent fashion. HLA-A2(+)/MAM-A(+) breast cancer patients have an increased prevalence of CD8 T cells specific for these novel MAM-A epitopes, and vaccination with a MAM-A DNA vaccine significantly increases the number of these CD8 T cells. The identification and translational validation of novel MAM-A epitopes has important implications for the ongoing clinical development of vaccine strategies targeting MAM-A. The novel MAM-A epitopes represent attractive targets for epitope-based vaccination strategies, and can also be used to monitor immune responses. Taken together these studies provide additional support for MAM-A as an important therapeutic target for the prevention and treatment of breast cancer.

Mammaglobin A: review and clinical utility.

Mammaglobin A is a protein that belongs to the secretoglobin superfamily. It has highly specific expression in cells from most breast cancers and may be used to detect circulating or disseminated tumor cells. In addition, mammaglobin A is currently under inves tigation as a potential therapeutic target for immune therapies that target breast cancer. The present review will highlight our current understanding of mammaglobin A at the genetic and protein level and its potential clinical applications. Characteristics of breast cancer and methods used to isolate and detect circulating tumor cells will also be presented.

The clinical utility of circulating tumor cells in breast cancer patients: detection by a quantitative assay of h-MAM gene expression.

The aim of this study was to evaluate tumor markers of molecular abnormalities that display tissue specificity, as to detect circulating tumor cells (CTCs) in breast cancer patients. Quantitative real-time RT-PCR was used to determine h-MAM, BCSG1, CK19, and c-erbB2 mRNA levels in peripheral blood (PB) of breast cancer patients. Results were compared with other epithelial cancers (lung or esophagus cancer), benign breast disease, and healthy individuals. We found that h-MAM mRNA was only detectable in the PB of patients with breast cancer (49 of 65, 75.4%), but not in patients with other epithelial cancers, benign breast disease, or healthy individuals. No significant differences in the expression level and positive detection rate of BCSG1, CK19, and c-erbB2 mRNA were observed between breast cancer and other epithelial cancers. Furthermore, the expression level and positive detection rate of h-MAM mRNA in PB were significantly correlated to the breast cancer pathologic stage (p=0.012 and p=0.015, respectively). Chemotherapy, radiotherapy, or total tumor resection (after 7 days of treatment) resulted in a significant decrease in the expression level of h-MAM mRNA in PB compared to the levels prior to the treatment (p<0.001). Importantly, an increase in h-MAM mRNA expression was detected in patients immediately after surgery, as well as 3 days post-surgery. These results indicate that the quantitative analysis of h-MAM mRNA is a useful tool for detecting CTCs in breast cancer patients, and can have a potential diagnostic utility in early micrometastasis, clinical evaluation of cancer treatment efficacy, and post-treatment monitoring of breast cancer patients.

Differential expression of secretoglobins in normal ovary and in ovarian carcinoma--overexpression of mammaglobin-1 is linked to tumor progression.

Secretoglobins (SCGB), such as mammaglobin 1 (MGB1, SCGB2A2), mammaglobin 2 (MGB2, SCGB2A1) and lipophilin B (LIPB, SCGB1D2), have been related to carcinogenesis. We profiled expression of MGB1, MGB2 and LIPB in human tissues and ovarian carcinoma and explored the impact of SCGB overexpression on cell proliferation. MGB1, MGB2 and LIPB mRNA are expressed at variable levels in most human tissues and we observed significant bilateral correlations between the different secretoglobins. Concerted overexpression of MGB1 and LIPB resulted in significant increase in cell proliferation. In clinical specimens of ovarian carcinoma we measured elevated concentrations of secretoglobin mRNA and for MGB1 this up-regulation was confirmed on the protein level. Overexpression of MGB1 positively correlated with the FIGO stage, the tumor grade and the mitotic index suggesting a patho-physiological role of the protein. Our data indicate that MGB1, MGB2 and LIPB mRNAs are expressed at low levels in human tissues but basal expression is upregulated in ovarian cancer. The in vivo correlation between nuclear MGB1 localization and the mitotic rate in ovarian cancer as well as the increased cell proliferation induced by secretoglobin overexpression in ovarian cancer cell lines suggest a pathophysiological role of these proteins in ovarian cancer.

A multimarker qPCR platform for the characterisation of endometrial cancer.

The molecular background of endometrial cancer (EC) has not been fully elucidated. In the present study, we developed a quantitative PCR (qPCR) platform to examine the gene dosages of the potential molecular markers MGB1, TOP2A, ERBB1-4, MYC, CCND1, ESR1 and PI3K. The platform was applied in samples collected from 157 EC patients (stage I-IV) to verify its clinical utility and to examine the diagnostic and prognostic significance of the analysed biomarkers. The gene dosage pattern of the ERBB family and its downstream effectors PI3K and MYC showed particularly strong correlations with clinicopathological data. The ERBB PI3K/Akt pathway was upregulated in 31 (20%) of 156 cases. Activation of the ERBB PI3K/Akt pathway was positively correlated with a higher stage (p=0.001), higher grade (p=0.001), histological type II disease (p=0.0003) and metastases (p=0.02). The implemented hierarchical clustering revealed that cluster 2 was characterised by high copy numbers of the studied genes. Cluster 2 was associated with shorter overall survival (p=0.05). The platform was found to be a fast and simple method for direct analysis of the genes involved in uterine carcinogenesis, making it feasible for EC biology characterisation.

Upregulation of human mammaglobin reduces migration and invasion of breast cancer cells.

Little is known about the biological role of human mammaglobin (hMAM) that is considered as a promising marker for breast cancer. Here, we investigated hMAM's role related to migration and invasion of human breast cancer cells (hBCC). Compared to normal cells, hBCC have high MAM mRNA expression levels. Of the hBCC tested, MAM mRNA expression levels were higher in noninvasive than in invasive cells. Overexpression of hMAM in breast cancer cells decreased migration and invasion, whereas knockdown of hMAM increased both. Taken together, these results suggest that metastasis of hBCC could be controlled by hMAM expression levels.

Electrochemical genosensor for detection of human mammaglobin in polymerase chain reaction amplification products of breast cancer patients.

Human mammaglobin (MG) has been found to be the most specific molecular marker for the hematogenous spread of breast cancer cells. In our study, an electrochemical impedance spectroscopic DNA biosensor was established for the detection of MG in breast cancer patients. The working conditions for the biosensor, such as immobilization time, rinse process, and hybridization process, were optimized. Under the optimal conditions, the charge transfer resistance of the proposed DNA biosensor shows excellent correlation with the amount of the complementary oligonucleotides in the range from 1.0 × 10(-9) to 2.0 × 10(-8) M. The detection limit is 5.0 × 10(-10) M. The proposed biosensor was used to detect the polymerase chain reaction amplification products of actual clinical breast cancer samples. The results were compared with that obtained by conventional gel electrophoresis. The results indicate that the electrochemical impedance spectroscopic assay is significantly sensitive and time-saving. The simple strategy described here is expected to be used in clinical application for early diagnosis of breast cancer.