mRNA markers of breast cancer nodal metastases: comparison between mammaglobin and carcinoembryonic antigen in 248 patients

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.

Detection of mammagloblin by RT-PCR as a biomarker for lymph node metastasis in breast cancer patients: A systematic review and meta-analysis

Background

This meta-analysis presents evidence regarding the diagnostic accuracy of mammaglobin detected using the RT-PCR technique, related to the presence of sentinel node metastasis in breast cancer patients.

Methods

The following databases were consulted: Cochrane, Lilacs, Scielo, Hinary, PubMed, Elsevier, Embase, ProQuest, the Universidad del Rosario´s Centro de Recursos Para el Aprendizaje y la Investigación (CRAI-UR) [Resource Center for Learning and Research], and the Google Scholar search engine. The quality of the studies was assessed using the QUADAS-2 and CASpe tools. The selected studies presented the necessary data to calculate diagnostic validity index of mammaglobin detection using RT-PCR, compared with the reference standard test. Global values for the sensitivity, specificity, positive predictive value, negative predictive value, probability ratios, diagnostic ORs, and summary ROC curves of this meta-analysis were obtained using the Meta-DiSc 1.4 program.

Results

Initially, 731 articles were obtained; but only 25 were included in the meta-analysis. Sensitivity was 84% (95% CI: 83% - 86%), and specificity was 92% (95% CI: 91% - 93%). Positive and negative predictive values were 9.26 (95% CI: 6.47–13.26) and 0.17 (95% CI: 0.13–0.23), respectively. The diagnostic OR was 66.34 (95% CI: 42.52–103.52). The predictive area under the sROC curve was 94.78 (Q = 0.8876).

Conclusions

The evaluated diagnostic index showed that the expression of the mammaglobin biomarker has diagnostic prediction for detecting lymph node metastasis in breast cancer patients, when analyzed using RT-PCR, although more than 50% heterogeneity was found.

Validation of a new algorithm for a quick and easy RT-PCR-based ALK test in a large series of lung adenocarcinomas: Comparison with FISH, immunohistochemistry and next generation sequencing assays

OBJECTIVES

Anaplastic Lymphoma Kinase (ALK) gene rearrangements have been described in 3-5% of lung adenocarcinomas (ADC) and their identification is essential to select patients for treatment with ALK tyrosine kinase inhibitors. For several years, fluorescent in situ hybridization (FISH) has been considered as the only validated diagnostic assay. Currently, alternative methods are commercially available as diagnostic tests.

MATERIAL AND METHODS

A series of 217 ADC comprising 196 consecutive resected tumors and 21 ALK FISH-positive cases from an independent series of 702 ADC were investigated. All specimens were screened by IHC (ALK-D5F3-CDx-Ventana), FISH (Vysis ALK Break-Apart-Abbott) and RT-PCR (ALK RGQ RT-PCR-Qiagen). Results were compared and discordant cases subjected to Next Generation Sequencing.

RESULTS

Thirty-nine of 217 samples were positive by the ALK RGQ RT-PCR assay, using a threshold cycle (Ct) cut-off ≤35.9, as recommended. Of these positive samples, 14 were negative by IHC and 12 by FISH. ALK RGQ RT-PCR/FISH discordant cases were analyzed by the NGS assay with results concordant with FISH data. In order to obtain the maximum level of agreement between FISH and ALK RGQ RT-PCR data, we introduced a new scoring algorithm based on the ΔCt value. A ΔCt cut-off level ≤3.5 was used in a pilot series. Then the algorithm was tested on a completely independent validation series. By using the new scoring algorithm and FISH as reference standard, the sensitivity and the specificity of the ALK RGQ RT-PCR(ΔCt) assay were 100% and 100%, respectively.

CONCLUSIONS

Our results suggest that the ALK RGQ RT-PCR test could be useful in clinical practice as a complementary assay in multi-test diagnostic algorithms or even, if our data will be confirmed in independent studies, as a standalone or screening test for the selection of patients to be treated with ALK inhibitors.

Mesenchymal phenotype of CTC-enriched blood fraction and lymph node metastasis formation potential

Introduction

Circulating tumor cells (CTCs) that present mesenchymal phenotypes can escape standard methods of isolation, thus limiting possibilities for their characterization. Whereas mesenchymal CTCs are considered to be more malignant than epithelial CTCs, factors responsible for this aggressiveness have not been thoroughly defined. This study analyzed the molecular profile related to metastasis formation potential of CTC-enriched blood fractions obtained by marker unbiased isolation from breast cancer patients without (N−) and with lymph nodes metastases (N+).

Materials and Methods

Blood samples drawn from 117 patients with early-stage breast cancer were enriched for CTCs using density gradient centrifugation and negative selection with anti-CD45 covered magnetic particles. In the resulting CTC-enriched blood fractions, expression of CK19, MGB1, VIM, TWIST1, SNAIL, SLUG, HER2, CXCR4 and uPAR was analyzed with qPCR. Results were correlated with patients' clinicopathological data.

Results

CTCs (defined as expression of either CK19, MGB1 or HER2) were detected in 41% (20/49) of N− and 69% (34/49) of N+ patients (P = 0.004). CTC-enriched blood fractions of N+ patients were more frequently VIM (P = 0.02), SNAIL (P = 0.059) and uPAR-positive (P = 0.03). Positive VIM, CXCR4 and uPAR status correlated with >3 lymph nodes involved (P = 0.003, P = 0.01 and P = 0.045, respectively). In the multivariate logistic regression MGB1 and VIM-positivity were independently related to lymph node involvement with corresponding overall risk of 3.2 and 4.2. Moreover, mesenchymal CTC-enriched blood fractions (CK19−/VIM+ and MGB1+ or HER2+) had 4.88 and 7.85-times elevated expression of CXCR4 and uPAR, respectively, compared with epithelial CTC-enriched blood fractions (CK19+/VIM− and MGB1+ or HER2+).

Conclusions

Tumors of N+ patients have superior CTC-seeding and metastatic potential compared with N- patients. These differences can be attributed to VIM, uPAR and CXCR4 expression, which endow tumor cells with particularly malignant phenotypes.

Relationship of CD44+CD24-/low breast cancer stem cells and axillary lymph node metastasis

BACKGROUND

Axillary node staging plays an important role in the prognostic evaluation and planning of adjuvant treatment. Breast cancer stem cells, identified on the basis of CD44+CD24-/low expression, are associated with metastases and drug resistance. It is therefore important to investigate the proportion of CD44+CD24-/low breast cancer stem cells for the diagnosis of metastases in axillary nodes.

METHODS

Thirty-two ipsilateral axillary lymph nodes were collected from patients diagnosed with invasive breast cancer. Each lymph node (LN) was divided into two equals - one was examined by H&E staining, while the other was made into a single cell suspension to study the content of CD44+CD24-/low cells by flow cytometry (FCM). The relationship was investigated between the content of CD44+CD24-/low cells and metastases in axillary nodes which were confirmed by histology. Associations were tested using the chi-square test (linear-by-linear association), and the significance level was set at a value of p < 0.05.

RESULTS

In the 32 axillary nodes, the level of CD44+CD24-/low cells was determined to be between 0 and 18.4%: there was no presence of CD44+CD24-/low cells in 9 LNs, of which 2 had confirmed metastasis; there were less than 10% CD44+CD24-/low cells in 12 LNs, of which 6 had confirmed metastasis; and there were more than 10% CD44+CD24-/low cells in 11 LNs, of which 9 had confirmed metastasis. A higher percentage of detected CD44+CD24-/low cells was significantly associated with more confirmed LN metastases (p = 0.009).

CONCLUSIONS

CD44+CD24-/low breast cancer stem cells might help clinicians to determine the presence of LN metastases. However, its prognostic value remains unclear, while histological diagnosis is still the gold standard.

Expression of human mammaglobin as a marker of bone marrow micrometastasis in breast cancer

The aim of the present study was to detect the expression of human mammaglobin (hMAM) mRNA in the bone marrow (BM) of patients with breast cancer and determine the relationship between micrometastasis and clinicopathological parameters as well as selected molecular markers and breast cancer prognosis. The expression of hMAM mRNA in the BM of patients with breast cancer was determined by RT-PCR. The expression of ER, PR and Cath-D in cancer tissues was detected by immunohistochemistry. A positive expression rate for hMAM of 38.2% in 102 patients with stage I-III breast cancer was found. The expression of hMAM was higher in patients with T(2-3) (>2 cm) tumors than in those with T(1) tumors (≤2 cm) (χ(2)=19.20, P=0.001) and in patients with stage II or III tumors than in patients with stage I tumors (χ(2)=15.101, P=0.001). The expression of hMAM in the BM of breast cancer patients categorized as grade 1 was lower than that in those of grade 2 or 3 (χ(2)=8.522, P=0.014), and hMAM expression was related to the pathological type of tumor (χ(2)=6.892, P=0.032) and the degree of axillary lymph node metastasis (χ(2)=14.050, P=0.001). The expression of hMAM in BM was much higher in patients with ER(-) or ER(+) tumors than in those with ER(++ or +++) (χ(2)=11.800, P=0.003), and those with PR (χ(2)=8.759, P=0.013). hMAM expression in BM was also significantly positively correlated with Cath-D expression (χ(2)=6.623, P=0.036). However, no correlation was found between hMAM expression and patient age (χ(2)=1.056, P=0.304). There was a strong correlation between patients with positive expression of hMAM in the BM and the presence of distant metastases (P=0.009). In conclusion, micrometastasis in the BM correlates with certain clinical pathological parameters and several tumor markers. Patients with positive expression of hMAM in the BM have a greater chance of distant metastasis and poor prognosis. The detection of micrometastasis may be one of the most advantageous markers for predicting the prognosis of breast cancer.

Technical limits of comparison of step-sectioning,immunohistochemistry and RT-PCR on breast cancer sentinel nodes: a study on methacarn-fixed tissue

The optimal pathological assessment of sentinel nodes (SLNs) in breast cancer is a matter of debate. Currently, multilevel histological evaluation and immunohistochemistry (IHC) are recommended, but alternative RT-PCR procedures have been developed. To assess the reliability of these different procedures, we devised a step-sectioning protocol at 100 micron-intervals of 74 SLNs using methacarn fixation. mRNA was extracted from sections collected from levels 4 to 5. Mammaglobin, CEA and CK19 were used for RT-PCR. mRNA extraction was successful in 69 SLNs. Of these, 7 showed macrometastases (>2mm), 2 showed micrometastases (<2 mm) and 7 showed isolated tumour cells (ITC) by IHC. RT-PCR was positive for the three markers in 6 of 7 macrometastases and in 1 of 2 micrometastases. In the 2 RT-PCR negative cases, metastases were detected only on sections distant from those analysed by RT-PCR. CEA and/or CK19 were positive by RT-PCR in 3 of 7 ITC and in 23 morphologically negative SLNs. In conclusion, the main goal of our study was to show that the use of alternate sections of the same sample for different procedures is the key reason for the discrepancies between molecular and morphological analyses of SLN. We believe that only prospective studies with quantitative mRNA analysis of specific metastatic markers on the whole lymph node can elucidate the utility of molecular assessments of SLN.

Positive bone marrow biopsy is associated with a decreased disease-free survival in patients with operable breast cancer

BACKGROUND

Bone marrow (BM) biopsy has been suggested as an independent prognostic factor in patients with breast cancer.

METHODS

Patients operated for breast cancer from June 2000 to April 2008 were enrolled in this protocol after signing an informed consent. After primary surgery, BM aspirate from the iliac crest was obtained and 5-10 cc of blood collected. Since 2002 a peripheral blood (PB) sample was also obtained. Both carcinoembryonic antigen (CEA) and Mammaglobin-specific nested reverse-transcription polymerase chain reaction (RT-PCR) were used to examine BM and PB samples. Physicians and patients were blinded to results.

RESULTS

Two hundred seventy-three patients underwent BM and/or PB test. The median age of the patients was 63 years (31-80 years), and the median tumor diameter was 1.5 cm (0.1-6 cm). BM aspirates were unsuccessful in nine patients, and RT-PCR was not technically feasible in 18 women, leaving 246 patients available for analysis of results and follow-up. Among them, 110 patients (45%) had either a BM or a PB test positive for CEA or Mammaglobin (Test+). At median follow-up of 60 months, 31 events (deaths or relapse) occurred (13%). Disease-free survival (DFS) was significantly lower in the Test+ group (BP and/or PB) (P<0.001). This effect was independent of nodal status. At 5 years, event-free survival for Node-/Test- patients was 46/49 (94%) and for Node+/Test+ patients was 21/33 (64%), while patients with only one status positive (Node-/Test+ or Node+/Test-) had an intermediate disease-free survival (35/43, 81%) (P=0.005). In a subgroup analysis, RT-PCR results for BM and Mammaglobin retained statistical significance on DFS (P<0.001), while those for PB and CEA did not.

CONCLUSIONS

This study confirms that RT-PCR of the BM is an independent prognostic factor for disease-free survival of breast cancer patients, and may improve their staging, allowing better strategies for therapy and follow-up.

Molecular oncology: current trends in diagnostics

Applications of molecular diagnostics to oncology have been slow to make their way to the clinical laboratory. While numerous genes and mutation spectra have been found to be involved in tumorigenesis, it is only recently that these findings begin to become useful in a clinical setting. Building on the technical knowledge obtained from molecular infectious disease testing, new instruments and assays have been developed to answer similar questions regarding qualitative, quantitative and genotyping issues. In this manuscript we describe two current examples of clinical molecular diagnostic applications, the assessment of BCR–ABL in chronic myelogenous leukemia patients and the detection of tumor cells in the sentinel lymph nodes of breast cancer patients, to demonstrate the role of molecular techniques in a routine clinical setting.

Characterization of the role of CD8+T cells in breast cancer immunity following mammaglobin-A DNA vaccination using HLA-class-I tetramers

INTRODUCTION

Mammaglobin-A(mam-A) is expressed in over 80% of human breast tumors. We recently reported that mam-A DNA vaccination resulted in breast cancer immunity in a preclinical model. Here we investigated whether mam-A HLA-class-I tetramers could be used to monitor and define the role of CD8(+)cytotoxic T-lymphocytes(CTL) in mediating breast cancer immunity following mam-A DNA vaccination.

STUDY DESIGN

Mam-A DNA vaccination was performed in HLA-A2(+)huCD8(+ )transgenic mice. HLA-A2 tetramers carrying the immunodominant mamA2.1 peptide were used to monitor CD8(+)CTL. Human breast cancer colonies were developed in immunodeficient SCID-beige mice. ELISPOT was used to correlate frequency of mamA2.1 tetramer(+)CD8(+)T cells and IFN-gamma production [spots per million cells (spm)] in human subjects.

RESULTS

Vaccination of HLA-A2(+)huCD8(+) mice with mam-A DNA vaccine, but not empty vector, led to the expansion of mamA2.1 tetramer(+)CD8(+)T-cells in peripheral blood (<0.5% pre-vaccination compared to >2.0% post-vaccination). CD8(+)T cells from vaccinated mice specifically lysed UACC-812(HLA-A2(+)/mam-A(+), 25% lysis) but not MDA-MB-415(HLA-A2(-)/mam-A(+)) or MCF-7(HLA-A2(+)/mam-A(-)) breast cancer cells. Adoptive transfer of purified CD8(+)T cells from vaccinated mice into immunodeficient SCID-beige mice with established human breast cancer colonies led to tetramer(+)CD8(+ )T-cell infiltration with regression of UACC-812 but not MCF-7 tumors. HLA-A2(+) breast cancer patients revealed increased frequency of mamA2.1 tetramer(+)CD8(+ )T-cells compared to normal controls (2.86 +/- 0.8% vs. 0.71 +/- 0.1%, P = 0.01) that correlated with the IFN-gamma response to mamA2.1 peptide (48.1 +/- 20.9 vs. 2.9 +/- 0.8 spm, P = 0.03).

CONCLUSIONS

CD8(+ )T-cells are crucial in mediating breast cancer immunity following mam-A DNA vaccination. Mam-A HLA-class-I tetramers can be effectively used to monitor development of CD8(+ )T-cells following mam-A vaccination.

Correlation between molecular metastases in sentinel lymph nodes of breast cancer patients and St Gallen risk category

AIMS

To evaluate the clinical significance of tumour metastases detected using real-time reverse transcription-PCR (RT-PCR) in sentinel lymph nodes (SLN) of breast cancer patients.

METHODS

Sixty-seven patients with T1-T2 primary breast cancer were included in a prospective study. SLN were analysed for the presence of metastatic tumour cells using standard histopathology staining, immunochemistry (IHC) and multimarker real-time RT-PCR assay for mammaglobin (MMG), carcinoembryonic antigen (CEA) and cytokeratin-19 (CK19) mRNA expression. Correlations between molecular metastases and traditional clinicopathological prognostic factors, including St Gallen risk categories were studied.

RESULTS

Of the 67 patients, 15 (22.3%) had one or more pathology-positive SLN. Five (9.6%) pathology-negative SLN were positive by IHC and 19 (36.5%) by RT-PCR. Of note, RT-PCR analysis was also positive in all cases with pathology- or IHC-positive SLN. MMG was the most informative tumour marker in the panel. Molecularly detected metastases were significantly associated with intermediate St Gallen risk category (p=0.023).

CONCLUSION

Molecular staging of SLN using real-time RT-PCR for early breast cancer could serve as a useful complement to standard clinicopathological risk factors. Studies with long-term follow-up are necessary to define the impact of molecular metastases on disease free survival and overall survival.

The clinical significance of disseminated tumor cells in breast cancer

The presence of tumor cells in the bone marrow of primary breast cancer patients at surgery has been shown to be an independent prognostic indicator of relapse. Tumor cells have been detected either directly, using immunocytochemical staining, or indirectly, using reverse transcription-polymerase chain reaction (RT-PCR). Studies have been initiated to determine whether the presence of disseminated cells can be monitored during the therapy of patients with primary breast cancer, and thus potentially be used to predict relapse before overt metastases are detectable. Studies are also ongoing to improve methods of detection, such as immunobead enrichment followed by staining and real-time RT-PCR, and to find alternative markers for the disseminated cells. Studies of patients with overt metastases have shown that there is a large tumor load in the peripheral blood and that this predicts overall survival. This article reviews the published literature on studies carried out in both primary and metastatic breast cancer patients, the methodologies and markers used, and improvements in detection methodologies that are being investigated including real-time RT-PCR, novel markers, enrichment and automated image analysis.

Assessing the status of axillary sentinel lymph nodes of breast carcinoma patients by a real-time quantitative RT-PCR assay for mammaglobin 1 mRNA

The aim of the study was to assess the accuracy of a real-time quantitative RT-PCR (qRT-PCR) assay for mammaglobin 1 mRNA in the detection of metastatic breast cancer in axillary sentinel lymph nodes (SLN), comparing the results with those of qualitative RT-PCR assays and of an extensive histopathological examination. A retrospective series of 81 SLN from 72 patients and a validation series of 61 SLN from 61 patients were evaluated. In the retrospective series, the qRT-PCR assay was positive for 23 (28.4%) of the 81 SLN. The overall concordance with histopathology was 93.8%, with a sensitivity of 90.9%, a specificity of 94.9%, a positive predictive value (PPV) of 87% and a negative predictive value (NPV) of 96.6%. In the same series, qualitative RT-PCR showed an overall concordance with histopathology of 86.4%, a sensitivity of 72.7%, a specificity of 91.5%, a PPV of 76.2% and a NPV of 90%. In the validation series, including 23 patients with pure in situ carcinoma, the real-time qRT-PCR assay showed an overall concordance with the histopathologic findings of 93.4%, with a sensitivity of 75.0%, a specificity of 94.7%, a PPV of 50.0% and a NPV of 98.2%. We conclude that real-time qRT-PCR assays for mammaglobin 1 are more sensitive and specific that qualitative RT-PCR assays for the detection of metastatic breast carcinoma in axillary SLN, but it should not be regarded as a possible substitute for an extensive histopathological scrutiny of the SLN in the clinical practice.

RT-PCR determination of maspin and mammaglobin B in peripheral blood of healthy donors and breast cancer patients

BACKGROUND

The aim of the present study was to evaluate the accuracy of two markers, maspin and mammaglobin B, singly or in combination, to detect breast cancer. To define better the potential and limits of the two markers for diagnostic purposes, blood positivity was analyzed in relation to clinical, pathological and biological tumor characteristics.

PATIENTS AND METHODS

The markers were determined in peripheral blood (PB) samples from 27 healthy donors and 140 previously untreated patients using nested reverse transcriptase polymerase chain reaction (RT-PCR).

RESULTS

Positivity for maspin in blood samples was observed in 24% of patients with an 89% specificity. For mammaglobin B, positivity was observed in 7% of patients and never in healthy donors. The presence of maspin was correlated with cell proliferation of the primary tumor (P = 0.015), whereas mammaglobin B positivity correlated with pathological stage (P = 0.013). The presence of either marker was significantly related to nodal status.

CONCLUSIONS

Our results indicate that the two markers in association could represent a potentially useful non-invasive tool to detect breast cancer. The validation of these markers as indicators of high risk of relapse is ongoing in a series of patients with an adequate follow-up.

Mammaglobin a in breast cancer: existence of multiple molecular forms

Existing serum-based markers for breast cancer all lack organ specificity. Mammaglobin A (MGA) is a 93 amino acid protein expressed almost exclusively in breast tissue. The aim of our study was to investigate the different forms of MGA protein in fibroadenomas and breast carcinomas. MGA protein was measured by Western blotting in 132 breast cancers, 29 fibroadenomas and 14 nonbreast tissues. MGA protein in breast tissue was found to exist in 2 main forms. These forms migrated with approximate molecular masses of 18 and 25 kDa. Both forms of MGA were detected more frequently in breast carcinomas compared to fibroadenomas. The high molecular weight form of MGA but not the low molecular weight form was found more frequently in hormone receptor-positive than in receptor-negative cancers. Furthermore, an inverse relationship was found between the high molecular weight form of MGA and both tumour grade and proliferation index. No significant correlation was found between the MGA proteins and either tumor size or nodal status. Our results show that MGA protein exists in 2 main forms in breast tissue. As the high molecular weight form correlated positively with hormone receptors and negatively with tumor grade and proliferation rate, its presence is likely to be associated with a favourable prognosis for breast cancer. As expression of MGA is almost breast specific, it is a promising marker for breast cancer. Its most immediate use is likely to be in detecting micrometastases from breast cancer.

Persistence of bone marrow micrometastases in patients receiving adjuvant therapy for breast cancer: Results at 4 years

We have previously developed a quantitative PCR (QPCR) technique for the detection of cytokeratin 19 (CK19) transcripts in blood and bone marrow and compared this to immunocytochemistry (ICC). Together, both have shown promise for monitoring therapeutic efficacy in patients with metastatic breast cancer. The aim of this study was to determine the feasibility and value of these assays for minimal residual disease (MRD) in monitoring efficacy of adjuvant therapy following surgery for primary breast cancer. Bone marrow aspirates and peripheral blood samples were taken at the time of surgery from patients with primary breast cancer and no evidence of metastases on conventional scans. These were tested for the presence of CK19 mRNA transcripts and cytokeratin positive cells. Follow-up bone marrow aspirates were taken at 3, 6, 12, 24, 36 and 48 months. Prior to surgery, 51% of patients displayed evidence of disseminated cancer cells in the bone marrow by either or both QPCR and ICC. Of 91 patients who had repeat samples assayed, 87% and 65% had positive results at some time using QPCR and ICC, respectively. All patients received adjuvant systemic therapy and in 44 cases where there was a positive result in either the pretreatment or 3-month aspirate, 32/44 (73%) showed a fall in CK19:ABL ratio (QPCR) and 15/24 (63%) showed a reduction in the number of cytokeratin-positive cells (ICC) during follow-up. These results indicate that MRD persists despite adjuvant therapy in a majority of patients with primary breast cancer up to 4 years following surgery.

Recognition of HLA-A2-restricted mammaglobin-A-derived epitopes

A breast cancer-associated antigen, mammaglobin-A, is specifically expressed in 80% of primary breast tumors. The definition of immune responses against this highly expressed breast cancer-specific antigen should be of great value in the development of new therapeutic strategies for breast cancer. Thus, the purpose of this study was to identify HLA-A2-restricted mammaglobin-A-derived epitopes recognized by CD8+ cytotoxic T lymphocytes (CTL). We identified seven mammaglobin-A-derived candidate epitopes that bind the HLA-A2 molecule (Mam-A2.1-7) by means of a HLA class I-peptide binding computer algorithm from the Bioinformatics & Molecular Analysis Section of the National Institutes of Health. Subsequently, we determined that CD8+ CTLs from breast cancer patients reacted to the Mam-A2.1 (83-92, LIYDSSLCDL), Mam-A2.2 (2-10, KLLMVLMLA), Mam-A2.3 (4-12, LMVLMLAAL), Mam-A2.4 (66-74, FLNQTDETL), and Mam-A2.7 (32-40, TINPQVSKT) epitopes using an IFN-gamma ELISPOT assay. Interestingly, healthy individuals also showed high reactivity to the Mam-A2.2 epitope. Two CD8+ CTL lines generated in vitro against TAP-deficient T2 cells loaded with the candidate epitopes showed significant cytotoxic activity against the Mam-A2.1-4 epitopes. These CD8+CTL lines recognized a HLA-A2+breast cancer cell line expressing the Mam-A2.1 epitope. In addition, DNA vaccination of HLA-A2+/human CD8+ double-transgenic mice with a DNA construct encoding the Mam-A2.1 epitope and the HLA-A2 molecule induced a significant expansion of epitope-specific CD8+ CTLs that recognize the same HLA- A2+/Mam-A2.1+ breast cancer cell line. In conclusion, these results demonstrate the immunotherapeutic potential of mammaglobin-A for the treatment and prevention of breast cancer.

Response of established human breast tumors to vaccination with mammaglobin-A cDNA

BACKGROUND

A novel breast cancer-associated antigen, mammaglobin-A, is expressed in 80% of primary breast tumors. The characterization of immune responses against this highly expressed breast cancer-specific antigen would be of value in the development of new therapeutic strategies for breast cancer.

METHODS

We developed an in vivo model using human leukocyte antigen-A*0201/human CD8+ (HLA-A2+/hCD8+) double-transgenic mice to define the epitopes and to study the level of protection acquired by mammaglobin-A cDNA vaccination toward mammaglobin-A+/HLA-A2+ breast cancer cell lines. Mammaglobin-A epitopes were identified using an HLA class I peptide binding prediction computer program, and their activity was verified using gamma interferon ELISPOT and cytotoxicity assays.

RESULTS

We identified seven mammaglobin-A-derived candidate epitopes that bind the HLA-A*0201 molecule (Mam-A2.1-7). CD8+ cytotoxic T lymphocytes (CTLs) from HLA-A2+/hCD8+ mice reacted to the Mam-A2.1 (amino acids [aa] 83-92, LIYDSSLCDL), Mam-A2.2 (aa 2-10, KLLMVLMLA), Mam-A2.4 (aa 66-74, FLNQTDETL), and Mam-A2.6 (aa 32-40, MQLIYDSSL) epitopes. CD8+ CTLs from breast cancer patients also recognized a similar epitope pattern as did those in the HLA-A2+/hCD8 mice and reacted to the Mam-A2.1, Mam-A2.2, Mam-A2.3, Mam-A2.4, and Mam-A2.7 epitopes. Passive transfer of mammaglobin-A-reactive CTLs into SCID (severe combined immunodeficient) beige mice with actively growing mammaglobin-A+ tumors resulted in statistically significant regression (P<.001) in the growth of the tumors.

CONCLUSIONS

The HLA-A2+/hCD8+ mouse represents a valuable animal model to characterize the HLA-A*0201-restricted CD8+ CTL immune response to mammaglobin-A in vivo, and the data reported here demonstrate the immunotherapeutic potential of mammaglobin-A for the treatment and/or prevention of breast cancer.

Molecular detection of micrometastatic breast cancer in histopathology-negative axillary lymph nodes correlates with traditional predictors of prognosis: an interim analysis of a prospective multi-institutional cohort study

OBJECTIVE

We sought to establish the clinical relevance of micrometastatic disease detected by reverse transcription polymerase chain reaction (RT-PCR) in axillary lymph nodes (ALN) of breast cancer patients.

BACKGROUND

The presence of ALN metastases remains one of the most valuable prognostic indicators in women with breast cancer. However, the clinical relevance of molecular detection of micrometastatic breast cancer in sentinel lymph nodes (SLN) and nonsentinel ALN has not been established.

METHODS

Four hundred eighty-nine patients with T1-T3 primary breast cancers were analyzed in a prospective, multi-institutional cohort study. ALN were analyzed by standard histopathology (H&E staining) and by multimarker, real-time RT-PCR analysis (mam, mamB, muc1, CEA, PSE, CK19, and PIP) designed to detect breast cancer micrometastases.

RESULTS

A positive marker signal was observed in 126 (87%) of 145 subjects with pathology-positive ALN, and in 112 (33%) of 344 subjects with pathology-negative ALN. In subjects with pathology-negative ALN, a positive marker signal was significantly associated with traditional indicators of prognosis, such as histologic grade (P = 0.0255) and St. Gallen risk category (P = 0.022). Mammaglobin was the most informative marker in the panel.

CONCLUSION

This is the first report to show that overexpression of breast cancer-associated genes in breast cancer subjects with pathology-negative ALN correlates with traditional indicators of disease prognosis. These interim results provide strong evidence that molecular markers could serve as valid surrogates for the detection of occult micrometastases in ALN. Correlation of real-time RT-PCR analyses with disease-free survival in this patient cohort will help to define the clinical relevance of micrometastatic disease in this patient population.

DNA fingerprints provide a patient-specific breast cancer marker

BACKGROUND

Detection of systemic breast cancer recurrence is limited by lack of universally expressed tumor cell markers. We hypothesized that a test that detects genetic alterations specific to breast cancer cells of an individual patient would provide a superior cancer marker.

METHODS

DNA was extracted from blood, primary tumor, and axillary lymph nodes of 33 breast cancer patients and normal breast tissue of 12 control patients. A patient's genome was scanned by PCR amplification between Alu sequences. A DNA fingerprint of approximately 17-40 bands was produced for comparison between normal blood and sampled tissues.

RESULTS

There were 7 stage I, 18 stage II, 7 stage III, and 1 stage IV breast cancer cases; 33 of 33 cancer cases showed DNA fingerprint differences between blood and primary tumor (P <.0001). This test predicted 100% of positive nodes. No false-negatives occurred, and in two cases malignancy was detected in histologically negative nodes. Three of the 12 controls showed a single similar band change.

CONCLUSIONS

DNA fingerprinting is a method for detecting and characterizing genetic alterations specific to an individual patient's primary tumor in 100% of cases tested. These specific changes were also identified in 100% of positive nodes, proving the capacity of the test to detect metastases.

Mammaglobin: a candidate diagnostic marker for breast cancer

Mammaglobin, known for its mammary tissue specificity, has been discussed as a promising diagnostic marker in breast cancer for almost 10 years. In particular, the application of mammaglobin RT-PCR to detect disseminated breast cancer cells has been reported. More than 25 publications evaluate the detection of mammaglobin mRNA in lymph node, blood, and bone marrow specimens of breast cancer patients. Recently, structural details about the mammaglobin complex have been discovered, and these findings can be implemented to optimize detection of the secreted protein. This review summarizes the findings of almost 50 published studies and the current knowledge about the diagnostic utility of mammaglobin.

Quantitative evaluation of metastases in axillary lymph nodes of breast cancer

We have established a highly sensitive and quantitative reverse transcriptase–polymerase chain reaction (RT–PCR) method to detect axillary lymph node metastases of breast cancer. Amplifying cytokeratin 19 (CK19) mRNA transcripts using real-time TaqMan PCR made it possible to quantify axillary metastatic burden. Metastases in 358 axillary lymph nodes obtained from 23 breast cancers of 22 patients were investigated by conventional haematoxylin and eosin (H&E) staining, immunohistochemical staining and quantitative RT–PCR assay. The detection rates of axillary lymph node metastasis using H&E staining, immunohistochemistry and RT–PCR assay were 4.5, 5.9 and 13.1%, respectively. RT–PCR assay was the most sensitive of these three methods for detecting lymph node metastases. Cytokeratin 19 mRNA expression values of both histologically and immunohistochemically positive lymph nodes were significantly higher than the values for lymph nodes judged to be negative by both histological and immunohistochemical methods (P<0.0001), and those of histologically negative, but immunohistochemically positive lymph nodes were significantly higher than the values for lymph nodes judged to be negative by both histological and immunohistochemical methods (P<0.0001). Furthermore, metastatic rates of sentinel nodes were higher than the rates of nonsentinel lymph nodes as measured by all three methods. These results indicate that quantitative RT–PCR assay is a sensitive and reliable method for detecting lymph node metastasis. Furthermore, quantification of metastases in sentinel lymph nodes by quantitative RT–PCR assay may be useful to assess the entire axillary burden of breast cancer patients.

Relationship between mammaglobin expression and estrogen receptor status in breast tumors

Mammaglobin (SCGB2A2) is a breast-specific member of the secretoglobin (SCGB) gene family. SCGB2A2 has previously been found overexpressed in breast tumors but possible associations between its expression and established prognostic tumor characteristics such as the levels of estrogen and progesterone receptors have not yet been investigated. We evaluated SCGB2A2 expression at the mRNA and at the protein level by reverse-transcription polymerase chain reaction and immunocytochemistry in 52 and 32 breast tumors, respectively. Both SCGB2A2 mRNA and protein expression were significantly higher in estrogen-receptor-positive compared to estrogen-receptor-negative tumors (Mann- Whitney rank sum test, p = 0.04; chi-square test, p = 0.01; respectively). In contrast, SCGB2A2 expression did not correlate with progesterone receptor levels or Nottingham grade. As estrogen and antiestrogen treatment of estrogen-positive breast cancer cell lines does not modify SCGB2A2 expression we suggest that SCGB2A2 may be a new independent breast cancer prognostic marker.

A novel method for increasing the expression level of recombinant proteins

Expression of recombinant proteins is an important step towards elucidating the functions of many genes discovered through genomic sequencing projects. It is also critical for validating gene targets and for developing effective therapies for many diseases. Here we describe a novel method to express recombinant proteins that are extremely difficult to produce otherwise. The increased protein expression level is achieved by using a fusion partner, MTB32-C, which is the carboxyl terminal fragment of the Mycobacterium tuberculosis antigen, MTB32 (Rv0125). By fusing MTB32-C to the N-termini of target genes, we have demonstrated significant enhancement of recombinant protein expression level in Escherichia coli. The inclusion of a 6xHis tag and the 128-amino acid of MTB32-C will add 13.5 kDa to the fusion molecule. Comparison of the mRNA levels of the fusion and non-fusion proteins indicated that the increased fusion protein expression may be regulated at translational or post-translational steps. There are many potential applications for the generated fusion proteins. For example, MTB32-C fusion proteins have been used successfully as immunogens to generate both polyclonal and monoclonal antibodies. These antibodies have been used to characterize cellular localization of the proteins and to validate gene targets at protein level. In addition, these antibodies may be useful in diagnostic and therapeutic applications for many diseases. If desired, the MTB32-C portion in the fusion protein can be removed after protein expression, making it possible to study protein structure and function as well as to screen for potential drugs. Thus, this novel fusion expression system has become a powerful tool for many applications.

Generation of CD8+ cytotoxic T lymphocytes against breast cancer cells by stimulation with mammaglobin-A-pulsed dendritic cells

Mammaglobin-A is exclusively expressed by breast cancer cells. Thus, mammaglobin-A-specific T cell immune responses may be useful for the design of new breast cancer-specific immunotherapies. We show herein that CD8+ T cells generated against recombinant mammaglobin-A-pulsed dendritic cells display a marked cytotoxic activity against mammaglobin-A-positive breast cancer cell lines. This study indicates the immunotherapeutic potential of this novel antigen for the treatment of breast cancer.

Detection of hepatocyte growth factor/scatter factor receptor (c-Met) in axillary drainage after operations for breast cancer using reverse transcriptase-polymerase chain reaction

BACKGROUND

The diverse biological effects of hepatocyte growth factor/scatter factor (HGF/SF) are mediated by c-Met, which is preferentially expressed on epithelial cells. Met signaling has a role in normal cellular activities, and may be associated with the development and progression of malignant processes. In this study we examined whether Met can be detected in the axillary drainage from patients who underwent conservative operations for breast cancer, and its prognostic significance.

METHODS

Thirty-one consecutive patients with invasive ductal carcinoma of the breast suitable for breast-conserving treatment were studied. The output of the drain that had been placed in the axilla during the operation was collected, and the presence of Met and beta-actin were assessed by reverse transcriptase-polymerase chain reaction (RT-PCR) assays. The data were compared with the pathological features of the tumor and the axillary lymph nodes, and with the estrogen receptor and progesterone receptor status.

RESULTS

RT-PCR of the axillary lymphatic drainage was positive for Met in 23 (74.2%) of the patients. Positive assays were correlated with increasing tumor size and grade, with capillary and lymphatic invasion, and with lymph node metastasis (P < 0.02, for all comparisons). All 12 patients with axillary lymph node metastases had positive assays for Met, compared with 57.9% of patients without lymph node metastases. All five patients with tumor involvement in the margins of the resection had positive assays for Met in their lymphatic fluid, compared with 18 of 26 positive assays (69.2%) for patients without involved margins (P < 0.04). Finally, Met showed negative correlations with positivity for estrogen receptor and progesterone receptor (P < 0.02).

CONCLUSION

Met can be detected in the axillary fluids of patients with breast cancer and its expression in the axillary drainage may have potential as a prognostic factor. This finding might be relevant to therapeutic considerations, because a positive assay for Met in histologically node-negative patients might point to the need to search for node microinvasion or involvement of the excision margins with tumor.

Use of a lectin affinity selector in the search for unusual glycosylation in proteomics

The purpose of the work described in this paper was to develop a new approach to the identification of glycoprotein with particular types of glycosylation. The paper demonstrates N-glycosylation sites in a glycoproteins can be identified by (1) proteolysis with trypsin, (2) lectin affinity selection, (3) enzymatic deglycosylation with peptide-N-glycosidase F (PNGase F) in buffer containing 95% H(2)(18)O, which generates deglycosylated peptide pairs separated by 2 or 4 amu, (4) reversed-phase separation of the peptide mixture and MALDI mass analysis, (5) MS-MS sequencing of the ion pairs, and (6) identification of the parent protein through a database search. This process has been tested on the selection of glycopeptides from lactoferrin and mammaglobin, and the identification of the ion pairs of fetuin glycopeptides. Glycosylation sites were identified through PNGase hydrolysis in H(2)(18)O. During the process of hydrolyzing the conjugate, Asn is converted to an aspartate residue with the incorporation of (18)O. However, PNGase F was observed to incorporate two (18)O into the beta-carboxyl groups of the Asp residue. This suggests that the hydrolysis is at least partially reversible.

Identification of HLA-A3-restricted CD8+ T cell epitopes derived from mammaglobin-A, a tumor-associated antigen of human breast cancer

Mammaglobin-A is highly overexpressed in breast cancer cell lines and primary breast tumors. This pattern of expression is restricted to mammary epithelium and metastatic breast tumors. Thus, mammaglobin-A-specific T cell immune responses may provide an important approach for the design of breast cancer-specific immunotherapy. The purpose of our study was to define the T cell-mediated immune response to mammaglobin-A. We determined that the frequency of mammaglobin-A-reactive CD8+ and CD4+ T cells in breast cancer patients is significantly higher than that observed in healthy female controls using limiting dilution analyses (p = 0.026 and p = 0.02, respectively). We identified 8 mammaglobin-A-derived 9-mer peptides with the highest binding affinity for the HLA-A3 molecule (Mam-A3.1-8) using a computer-assisted analysis of the mammaglobin-A protein sequence. Subsequently, we determined that CD8+ T cells from breast cancer patients reacted to peptides Mam-A3.1 (23-31, PLLENVISK), Mam-A3.3 (2-10, KLLMVLMLA), Mam-A3.4 (55-63, TTNAIDELK) and Mam-A3.8 (58-66, AIDELKECF) using an IFN-gamma enzyme-linked immunospot assay. A CD8+ T cell line generated in vitro against HLA-A*0301-transfected TAP-deficient T2 cells loaded with these peptides showed significant cytotoxic activity against the Mam-A3.1 peptide. This CD8+ T cell line showed a significant HLA-A3-restricted cytotoxic activity against mammaglobin-A-positive but not mammaglobin-A-negative breast cancer cells. In summary, our study identified four HLA-A3-restricted mammaglobin-A-derived epitopes naturally expressed by breast cancer cells, indicating the immunotherapeutic potential of this novel antigen for the treatment and prevention of breast cancer.

Mammaglobin expression in gynecologic malignancies and malignant effusions detected by nested reverse transcriptase-polymerase chain reaction

The detection of micrometastatic disease remains a challenge for the diagnosis and monitoring of malignant disease. RT-PCR for human mammaglobin (hMAM) was recently shown to provide a sensitive method for assessing circulating breast cancer cells in peripheral blood. This study was aimed at investigating hMAM expression in normal and malignant tissue from the female genital tract and the prostate as well as in malignant effusions derived from gynecologic malignancies. hMAM expression was analyzed with nested RT-PCR in 152 samples of normal (n = 73) and malignant epithelial tissues (n = 79) and in 33 specimens of various normal mesenchymal tissue types. We found hMAM expression was not restricted to the normal mammary gland and breast carcinoma but was also detectable in most specimens of benign and malignant epithelial tissue from the ovary (97% versus 95%), uterus (both 100%), and cervix (91% versus 90%). Notably, hMAM expression was also found in benign prostatic hyperplasia (45%) and in prostate cancer (55%). A much lower expression rate was found in various normal and benign mesenchymal tissues (12%). In keeping with our previous data, hMAM expression was absent in all control samples (n = 124) of peripheral blood and bone marrow from healthy volunteers and patients with hematologic malignancies. In pleural or peritoneal effusions (n = 42) from patients with carcinomas of the breast, endometrium, or ovary, hMAM positivity was noticed in the majority of cases (74%), whereas only 52% of the specimens were cytologically positive for tumor cells. In conclusion, hMAM expression assessed by nested RT-PCR is a sensitive molecular marker for detecting micrometastatic tumor spread into pleural effusions and ascites from patients with breast cancer and various other gynecologic neoplasms.

Optimisation of the RT-PCR detection of immunomagnetically enriched carcinoma cells

BACKGROUND

Immunomagnetic enrichment followed by RT-PCR (immunobead RT-PCR) is an efficient methodology to identify disseminated carcinoma cells in the blood and bone marrow. The RT-PCR assays must be both specific for the tumor cells and sufficiently sensitive to enable detection of single tumor cells. We have developed a method to test RT-PCR assays for any cancer. This has been investigated using a panel of RT-PCR markers suitable for the detection of breast cancer cells.

METHODS

In the assay, a single cell line-derived tumor cell is added to 100 peripheral blood mononuclear cells (PBMNCs) after which mRNA is isolated and reverse transcribed for RT-PCR analysis. PBMNCs without added tumor cells are used as specificity controls. The previously studied markers epidermal growth factor receptor (EGFR), mammaglobin 1 (MGB1), epithelial cell adhesion molecule (EpCAM/TACSTD1), mucin 1 (MUC1), carcinoembryonic antigen (CEA) were tested. Two new epithelial-specific markers ELF3 and EphB4 were also tested.

RESULTS

MUC1 was unsuitable as strong amplification was detected in 100 cell PBMNC controls. Expression of ELF3, EphB4, EpCAM, EGFR, CEA and MGB1 was found to be both specific for the tumor cell, as demonstrated by the absence of a signal in most 100 cell PBMNC controls, and sensitive enough to detect a single tumor cell in 100 PBMNCs using a single round of RT-PCR.

CONCLUSIONS

ELF3, EphB4, EpCAM, EGFR, CEA and MGB1 are appropriate RT-PCR markers for use in a marker panel to detect disseminated breast cancer cells after immunomagnetic enrichment.