Steroid receptor heterogeneity in relation to DNA index in breast cancer: a multiparameter flow cytometric approach on paraffin-embedded tumor samples

A novel, automated technology for multiplex biomarker imaging and application to breast cancer

AIMS

Multiplexed immunofluorescence is a powerful tool for validating multigene assays and understanding the complex interplay of proteins implicated in breast cancer within a morphological context. We describe a novel technology for imaging an extended panel of biomarkers on a single, formalin-fixed paraffin-embedded breast sample and evaluating biomarker interaction at a single-cell level, and demonstrate proof-of-concept on a small set of breast tumours, including those which co-express hormone receptors with Her2/neu and Ki-67.

METHODS AND RESULTS

Using a microfluidic flow cell, reagent exchange was automated and consisted of serial rounds of staining with dye-conjugated antibodies, imaging and chemical deactivation. A two-step antigen retrieval process was developed to satisfy all epitopes simultaneously, and key parameters were optimized. The imaging sequence was applied to seven breast tumours, and compared with conventional immunohistochemistry. Single-cell correlation analysis was performed with automated image processing.

CONCLUSIONS

We have described a novel platform for evaluating biomarker co-localization. Expression in multiplexed images is consistent with conventional immunohistochemistry. Automation reduces inconsistencies in staining and positional shifts, while the fluorescent dye cycling approach dramatically expands the number of biomarkers which can be visualized and quantified on a single tissue section.

Multiparameter DNA content analysis identifies distinct groups in primary breast cancer

Background:

Multiparameter flow cytometry is a robust and reliable method for determining tumour DNA content applicable to formalin-fixed paraffin-embedded (FFPE) tissue. This study examined the clinical and pathological associations of DNA content in primary breast cancer using an improved multiparametric technique.

Methods:

The FFPE tissue from 201 primary breast cancers was examined and the cancers categorised according to their DNA content using multiparametric flow cytometry incorporating differential labelling of stromal and tumour cell populations. Mathematical modelling software (ModFit 3.2.1) was used to calculate the DNA index (DI) and percentage S-phase fraction (SPF%) for each tumour. Independent associations with clinical and pathological parameters were sought using backward stepwise Binary Logistic Regression (BLR) and Cox's Regression (CR) analysis.

Results:

Tumours were grouped into four categories based on the DI of the tumour cell population. Low DI tumours (DI=0.76–1.14) associated with progesterone receptor-positive status (P=0.012, BLR), intermediate DI (DI=1.18–1.79) associated with p53 mutant tumours (P=0.001, BLR), high DI (DI⩾1.80) tumours with human epidermal growth factor receptor 2 (HER2)-positive status (P=0.004, BLR) and ‘multiploid tumours' (two or more tumour DNA peaks) did not show any significant associations. Tumours with high SPF% (⩾10%) independently associated with poor overall survival (P=0.027, CR).

Conclusion:

Multiparametric flow analysis of FFPE tissue can accurately assess tumour DNA content. Tumour sub-populations associated with biomarkers of prognosis or likely response to therapy. The alterations in DNA content present the potential for greater understanding of the mechanisms underlying clinically significant biomarker changes in primary breast cancer.

Clinical implications of gene dosage and gene expression patterns in diploid breast carcinoma

PURPOSE

Deregulation of key cellular pathways is fundamental for the survival and expansion of neoplastic cells. In cancer, regulation of gene transcription can be mediated in a variety of ways. The purpose of this study was to assess the impact of gene dosage on gene expression patterns and the effect of other mechanisms on transcriptional levels, and to associate these genomic changes with clinicopathologic parameters.

EXPERIMENTAL DESIGN

We screened 97 invasive diploid breast tumors for DNA copy number alterations and changes in transcriptional levels using array comparative genomic hybridization and expression microarrays, respectively.

RESULTS

The integrative analysis identified an increase in the overall number of genetic alterations during tumor progression and 15 specific genomic regions with aberrant DNA copy numbers in at least 25% of the patient population, i.e., 1q22, 1q22-q23.1, 1q25.3, 1q32.1, 1q32.1-q32.2, 8q21.2-q21.3, 8q22.3, 8q24.3, and 16p11.2 were recurrently gained, whereas 11q25, 16q21, 16q23.3, and 17p12 were frequently lost (P < 0.01). An examination of the expression patterns of genes mapping within the detected genetic aberrations identified 47 unique genes and 1 Unigene cluster significantly correlated between the DNA and relative mRNA levels. In addition, more malignant tumors with normal gene dosage levels displayed a recurrent overexpression of UBE2C, S100A8, and CBX2, and downregulation of LOC389033, STC2, DNALI1, SCUBE2, NME5, SUSD3, SERPINA11, AZGP1, and PIP.

CONCLUSIONS

Taken together, our findings suggest that the dysregulated genes identified here are critical for breast cancer initiation and progression, and could be used as novel therapeutic targets for drug development to complement classical clinicopathologic features.

DNA flow cytometry of canine mammary tumors: comparative aspects with human breast tumors

Flow cytometric analysis of DNA content was performed on 28 samples of canine mammary tumors. Nine of them were benign and 19 were malignant. All benign tumors and 11 malignant tumors (57.9%) were diploid (P<0.05). Form the aneuploid tumors, five (26.3%) were hyperdiploid, one (5.3%) hypodiploid, one (5.3%) near triploid and one (5.3%) multiploid. The analysis of the expression of the markers PR and CD31 revealed a significant difference between diploid and aneuploid tumors (P<0.05). The immunoreactivity of PR was higher in diploid tumors, while the immunoreactivity of CD31 was stronger in aneuploid tumors. No difference between the markers MIB-1, c-erbB2, p53 and Cyclin D1 was observed (P>0.05). Using the flow cytometry analysis and immunohistochemistry, it was found a close relationship between aneuploidy and malignant character of neoplasias, progesterone receptor (PR) negative immunostaining and higher microvases density. No correlation between DNA content and S phase or immunoreactivity for the markers MIB-1, p53, c-erbB2 and Cyclin D1 was observed.

Determination of threshold values for determining the size of the fraction of steroid hormone receptor-positive tumor cells in paraffin-embedded breast carcinomas

BACKGROUND

For 4 years we used a multiparameter DNA flow cytometric (MP-FCM) technique to assess steroid hormone receptor expression in the diagnostic workup of routinely processed formalin-fixed, paraffin-embedded breast carcinomas as an alternative to immunohistochemistry (IHC) for the quantification of hormone receptor-positive cells. In all cases a positive fraction of hormone receptor-expressing epithelial cells was detected. This observation raised the question of what the cutoff value might be to distinguish receptor-negative from receptor-positive tumors.

METHODS

In our search for a possible threshold value of positivity for estrogen receptor (ER) and progesterone receptor (PR) in MP-FCM, we developed four steps. First, we compared IHC results in our own laboratory with the results obtained by MP-FCM on a small series of breast tumors (n = 42). Second, after collecting our first 843 tumors, we made a comparison with the literature of the distribution of receptor positivity according to age classes. Third, using the most likely threshold that resulted from this comparison, we compared a subset of 340 node-negative tumors for their combined ER/PR profiles with the data from a similar group of node-negative tumor cases from the National Cancer Institute's Surveillance, Epidemiology and End-Result (SEER) study. Fourth, with the results of these comparisons, we prospectively collected IHC data and MP-FCM results of the same tumor samples for a period of 1 year. In this way, we collected data for an additional 180 tumors.

RESULTS

The first step in this process resulted in an previous publication where 20% of steroid hormone receptor-positive cells seemed to be an acceptable cutoff point for positivity. However, the second step provided the best correlation at approximately 35% of ER reactive cells in the cytokeratin-positive cell population. With this cutoff, the distribution of combined ER/PR profiles in our patient population of node-negative breast cancers also showed a distribution similar to the data from the SEER study. The fourth step, using the 35% threshold value, resulted in a good correlation (r = 0.85, P < 0.0001) for ER and PR between IHC and MP-FCM in the 180 tumors investigated.

CONCLUSION

By comparing in-house data with those from large external data collections in the literature, a threshold percentage can be defined that distinguishes steroid hormone receptor-negative from hormone receptor-positive tumors. As a result, information about DNA content and cell cycle distribution can be obtained. This observational study provides additional support to our opinion that MP-FCM is an alternative for IHC determination of ER and PR positivity. It is more objective and quantification can be done more appropriately. The additional value of this approach is that we generate continuous variables of ER/PR content instead of categorical classes, which can be used at different threshold levels for evaluation of clinical relevance.

The p160 family coactivators regulate breast cancer cell proliferation and invasion through autocrine/paracrine activity of SDF-1alpha/CXCL12

Estrogen receptors (ERs) regulate the transcription of genes involved in breast cancer cell proliferation, invasion and metastasis. In addition to ligand concentration, phosphorylation and coactivator/corepressor levels control ER-dependent transcription. In this study, we used MCF-7 breast cancer sublines with variable levels of the steroid receptor coactivator 1 (SRC-1) to investigate the importance of coactivator levels in basal and estrogen-inducible expression of SDF-1alpha/CXCL12, cathepsin D and cMyc. Basal expression of SDF-1alpha and cMyc but not of cathepsin D was substantially lower in a MCF-7 subline lacking SRC-1 ((MCF-7/p2) compared with MCF-7 sublines expressing SRC-1 (MCF-7/p1 and LCC2). Although estrogen efficiently induced SDF-1alpha in MCF-7/p1 cells, very little induction of this gene was observed in MCF-7/p2 cells. The absence of SRC-1 had no effect on estrogen-inducible expression cMyc and cathepsin D suggesting that coactivator levels determine the expression of only a subset of estrogen-regulated genes. Introduction of SRC-1, SRC-2/TIF-2 or SRC-3/AIB1 increased basal expression of SDF-1alpha in MCF-7/p2 cells. Consistent with the role of SDF-1alpha in mediating estrogen-induced proliferation, estrogen failed to increase proliferation of MCF-7/p2 cells. In matrigel invasion assays, conditioned media from MCF-7/p1 but not MCF-7/p2 cells increased invasion of cancer cells expressing metastasis-associated genes and CXCR4, the receptor for SDF-1alpha. These results suggest that coactivators control SDF-1alpha expression, which mediates estrogen-induced proliferation and invasion through autocrine and paracrine mechanisms, respectively. These results also provide a molecular explanation for recent observations linking co-overexpression of coactivators and her2/neu with poor prognosis: coactivators increase SDF-1alpha expression whereas her2/neu stabilize CXCR4 protein.

Tumor Markers in Breast Cancer – European Group on Tumor Markers Recommendations

Recommendations are presented for the routine clinical use of serum and tissue-based markers in the diagnosis and management of patients with breast cancer. Their low sensitivity and specificity preclude the use of serum markers such as the MUC-1 mucin glycoproteins (CA 15.3, BR 27.29) and carcinoembryonic antigen in the diagnosis of early breast cancer. However, serial measurement of these markers can result in the early detection of recurrent disease as well as indicate the efficacy of therapy. Of the tissue-based markers, measurement of estrogen and progesterone receptors is mandatory in the selection of patients for treatment with hormone therapy, while HER-2 is essential in selecting patients with advanced breast cancer for treatment with Herceptin (trastuzumab). Urokinase plasminogen activator and plasminogen activator inhibitor 1 are recently validated prognostic markers for lymph node-negative breast cancer patients and thus may be of value in selecting node-negative patients that do not require adjuvant chemotherapy.

Multiparameter flow cytometry as a tool for the detection of micrometastatic tumour cells in the sentinel lymph node procedure of patients with breast cancer

AIM

To investigate whether multiparameter flow cytometry (MP-FCM) can be used for the detection of micrometastasis in sentinel lymph nodes (SLNs) in breast cancer.

METHODS

Formalin fixed, paraffin wax embedded sentinel lymph nodes (n = 238) from 98 patients were analysed. For each lymph node, sections for haematoxylin and eosin (H&E) staining and immunohistochemistry (IHC) for cytokeratin (MNF116) were cut at three levels with a distance of 500 microm. The intervening material was used for MP-FCM. Cells were immunostained with MNF116, followed by an incubation with fluorescein isothiocyanate (FITC) labelled goat antimouse immunoglobulin. DNA was stained using propidium iodide. From each lymph node 100,000 cells were analysed on the flow cytometer.

RESULTS

Thirty eight of the 98 patients with breast carcinoma showed evidence of metastatic disease in the SLN by one ore more of the three methods. In 37 of 38 cases where metastatic cells were seen in the routine H&E and/or IHC, more than 1% cytokeratin positive cells were detected by MP-FCM. In 24 patients, metastatic foci were more than 2 mm (macrometastasis) and in 14 these foci were smaller than 2 mm (micrometastasis). In three of these 14 cases, MP-FCM revealed positive SLNs, although this was not seen at first glance in the H&E or IHC sections. After revision of the slides, one of these three remained negative. However, MP-FCM analysis of the cytokeratin positive cells showed an aneuploid DNA peak, which was almost identical to that of the primary breast tumour. Duplicate measurements, done in 41 cases, showed a 99% reproducibility. In five of 14 patients with micrometastasis, one or two metastatic foci were found in the non-SLN. However, in 15 of 24 macrometastases multiple non-SLNs were found to have metastatic tumour. All micrometastases except for the remaining negative one mentioned above showed only diploid tumour cells, despite the fact that their primary tumours contained both diploid and aneuploid tumour cells. In primary tumours with more than 60% aneuploid cells, predominantly aneuploid macrometastasis were found, whereas diploid primary tumours only showed diploid micrometastases or macrometastases in their SLN. Aneuploid SLN macrometastases were associated with non-SLN metastases in five of seven patients, whereas diploid cases showed additional non-SLN metastases in only seven of 16 patients.

CONCLUSION

In all cases, MP-FCM was sufficient to detect micrometastatic tumour cells in a large volume of lymph node tissue from SLNs. In some cases it was superior to H&E and IHC staining. Approximately 30% of SLN micrometastases are accompanied by additional non-SLN metastases. The size of the aneuploid fraction (> 60%) in the primary tumour may influence the risk of having both SLN and non-SLN metastases.