Sensitive fluorescent in situ hybridisation method for the characterisation of breast cancer cells in bone marrow aspirates

Emerging applications of fluorescent nanocrystals quantum dots for micrometastases detection

The occurrence of metastases is one of the main causes of death in many cancers and the main cause of death for breast cancer patients. Micrometastases of disseminated tumour cells and circulating tumour cells are present in more than 30% of breast cancer patients without any clinical or even histopathological signs of metastasis. Low abundance of these cell types in clinical diagnostic material dictates the necessity of their enrichment prior to reliable detection. Current micrometastases detection techniques are based on immunocytochemical and molecular methods suffering from low efficiency of tumour cells enrichment and observer-dependent interpretation. The use of highly fluorescent semiconductor nanocrystals, also known as "quantum dots" and nanocrystal-encoded microbeads tagged with a wide panel of antibodies against specific tumour markers offers unique possibilities for ultra-sensitive micrometastases detection in patients' serum and tissues. The nanoparticle-based diagnostics provides an opportunity for highly sensitive parallel quantification of specific proteins in a rapid and low-cost method, thereby providing a link between the primary tumour and the micrometastases for early diagnosis.

Osteoblast-induced EGFR/ERBB2 signaling in androgen-sensitive prostate carcinoma cells characterized by multiplex kinase activity profiling

Bone metastases in prostate cancer are predominantly osteoblastic. To study regulatory mechanisms underlying the establishment of prostate cancer within an osteoblastic microenvironment, human androgen-sensitive prostate carcinoma cells (LNCaP) were treated with culture medium conditioned by human osteoblast-derived sarcoma cells (OHS), and activated signalling pathways in the carcinoma cells were analyzed using microarrays with tyrosine kinase substrates. Network interaction analysis of substrates with significantly increased phosphorylation levels revealed that signalling pathways mediated by EGFR and ERBB2 were activated in LNCaP cells under OHS influence but also by androgen treatment. Activation of EGFR/ERBB2 signalling was also found in LNCaP cells in cocultures with OHS cells or osteoblastic cells that had been differentiated from human mesenchymal stem cells. Our experimental data suggests osteoblast-directed induction of signalling activity via EGFR and ERBB2 in prostate carcinoma cells and may provide a rationale for the use of EGFR or ERBB2 inhibition in systemic prevention or treatment of metastatic prostate cancer in the androgen-sensitive stage of the disease.

Recent advances in the detection of bone marrow micrometastases: A promising area for research or just another false hope? A review of the literature

The presence of early disseminated tumor cells (DTC), otherwise termed micrometastases or minimal residual disease, in the bone marrow (BM), or other secondary compartments, such as the blood and the lymph nodes, is the main reason for recurrence of patients with early stage epithelial cancers after "curative" resection of the primary tumor. There is increasing evidence, that the detection of DTC in BM aspirates may provide additional and independent prognostic information and aid in the stratification of these patients for adjuvant clinical treatment. However, the clinical relevance of micrometastases has not yet been firmly established. In addition, the molecular events and interactions that prevail in early metastatic disease and determine the formation or not of overt metastases remain poorly understood. The methods currently used for the detection of micrometastatic cells include extremely sensitive immunocytochemical and molecular assays, often in conjunction with enrichment techniques for the purification of tumor cells and additional increase of their sensitivity. Nevertheless, the specificity of these methods is mostly inadequate. After the impressive advances of molecular cytogenetics, a highly accurate and global assessment of the genetic status of tumors is now possible. Therefore, the greatest challenge of our time is the application of these novel technologies for the clarification of the key molecular events that initiate metastatic spread. This will further enable us to identify the highly specific and sensitive diagnostic and prognostic markers as well as the therapeutic targets which are so urgently needed.

Chemokine receptor CXCR4 expression in breast cancer as a potential predictive marker of isolated tumor cells in bone marrow

Interactions between the CXCR4 chemokine receptor in breast cancer cells and the ligand CXCL12/SDF-1alpha are thought to play an important role in breast cancer metastases. In this pilot study, CXCR4 expression along with other biomarkers including HER2-neu and EGFR, were measured in primary tumor samples of patients with operable breast cancer to test whether any of these biomarkers alone and in combination could indicate breast cancer with high likelihood of metastasizing to bone marrow. Cytokeratin (CK) positive cells in bone marrow were identified by flow-cytometry following enrichment with CK 7/8 antibody-coupled magnetic beads. Primary tumors (n = 18) were stained with specific antibodies for CXCR4, HER2-neu, EGFR, and PCNA using an indirect avidin-biotin horseradish peroxidase method. The majority of the patients had T2/T3 tumors (72%), or lymph node involvement (67%) as pathologic characteristics that were more indicative of high-risk breast cancer. High CXCR4 cytoplasmic expression was found in 7 of 18 patients (39%), whereas 6 of 18 patients (33%) were found to have CK positivity in bone marrow. The median number of CK(+) cells was 236 (range, 20-847) per 5 x 10(4) enriched BM cells. The presence of CK(+) cells in bone marrow was found to be associated with increased expression of CXCR4 alone or in addition to EGFR and/or HER2-neu expression (P = 0.013, P = 0.005, and P = 0.025, respectively) in primary tumors. Furthermore, three patients with high CK positivity (>236 CK(+) per 5 x 10(4) enriched bone marrow cells) in bone marrow exclusively expressed high levels of CXCR4 with EGFR/HER2-neu (P = 0.001). Our data suggest that high CXCR4 expression in breast cancer may be a potential marker in predicting isolated tumor cells in bone marrow. CXCR4 coexpression with EGFR/HER2-neu might further predict a particular subset of patients with high CK positivity in bone marrow.

Prognosis of Non–Small Cell Lung Cancer Patients by Detecting Circulating Cancer Cells in the Peripheral Blood with Multiple Marker Genes

Purpose: Current lung cancer staging and prognosis methods are based on imaging methods, which may not be sensitive enough for early and accurate detection of metastasis. This study aims to validate the use of a panel of markers for circulating cancer cell detection to improve the accuracy of cancer staging, prognosis, and as a rapid assessment of therapeutic response.

Experimental Design: We analyzed the National Cancer Institute-Cancer Genome Anatomy Project database to identify potential marker genes for the detection of circulating cancer cells in peripheral blood. Nested real-time quantitative PCR and a scoring method using cancer cell load Lc were employed to correlate the amount of circulating cancer cells with clinical outcomes in 54 non–small cell lung cancer (NSCLC) patients. The Kaplan-Meier method was employed for analysis of prognostic variables.

Results: A panel of four marker genes was identified and experimentally validated. With these marker genes, we achieved an overall positive detection rate of 72% for circulating cancer cells in the peripheral blood of NSCLC patients. Patients who had higher Lc values had worse outcomes and shorter survival times. Patients with poor therapeutic response were revealed by positive detection of circulating cancer cells after therapy. The results correlated well with the patients' survival time.

Conclusion: Circulating cancer cell detection by a panel of markers and the Lc scoring method can supplement the current tumor, node, metastasis staging method for improved prognosis and for rapid assessment of therapeutic response. Together, they may facilitate the design of better therapeutic strategies for the treatment of NSCLC patients.

A relevant immunomagnetic assay to detect and characterize epithelial cell adhesion molecule-positive cells in bone marrow from patients with breast carcinoma: immunomagnetic purification of micrometastases

BACKGROUND

The efficient detection and characterization of micrometastatic cells in the bone marrow of patients with breast carcinoma are of prognostic and therapeutic importance. The technique used must overcome the challenges that result from the small number of target cells (1 per 1 million hematopoietic cells) and the heterogeneous expression of micrometastatic cell markers. In this study, the authors assessed and improved the current methods for purifying and characterizing rare disseminated carcinoma cells.

METHODS

The authors developed a single-step assay that does not require density-gradient separation. This assay can be performed directly on crude human bone marrow aspirates and is based on the use of immunomagnetic beads coated with an antibody that recognizes an epithelial cell-surface epitope, the epithelial cell adhesion molecule (EpCAM). To determine the specificity of the assay, the authors evaluated bone marrow specimens from 46 control patients.

RESULTS

The novel method was highly reproducible and was capable of detecting as few as 10 carcinoma cells among 50 million hematopoietic cells. The yield was nearly 100%, with only 0.01% nonspecific cell draining. The authors found that 68 +/- 51 cells were trapped per 50 million cells in control crude aspirates and that density-gradient separation increased this number by 2-fold to 29-fold. These trapped cells expressed EpCAM, represented 1.4 x 10(-4) % of the sample, and were characterized as of hematopoietic cell origin (CD45 positive) or progenitor cell origin (CD34 positive).

CONCLUSIONS

The authors developed a highly efficient and reproducible, single-step immunomagnetic assay that may be performed directly on crude human bone marrow aspirates. The authors believe the current study is the first to demonstrate that some rare bone marrow cells (CD45-positive or CD34-positive cells) may express EpCAM and, to some extent, may contaminate the purified micrometastatic cell fraction. Thus, a universal marker for micrometastatic cells remains to be discovered.

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

Introduction

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

Methods

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

Results

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

Conclusion

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

Relevance of disseminated tumour cells in blood and bone marrow of patients with solid epithelial tumours in perspective

Currently-used systems to predict prognosis in patients with solid epithelial tumours after surgical resection of the tumour do not give any guarantees for the individual patient. In this respect the clinical relevance of the presence of disseminated tumour cells in blood and bone marrow has been frequently studied. Because of growing awareness that information on merely the presence of disseminated tumour cells is not sufficient for prognostic and therapeutic purposes, attention for characterization of disseminated tumour cells has increased. Numerous reviews have already been published on the detection and clinical relevance of disseminated tumour cells. Therefore, this paper will mainly focus on the biological significance of these cells and discusses the (in)efficiency of the metastatic process, the genotypic and phenotypic characteristics of disseminated tumour cells, and their structure of appearance. Despite the fact that information gained on the several individual aspects is substantial, it did not render any solid solutions for individual patient management yet. Hence, a combined approach of several aspects of disseminated tumour cells together with characteristics and behaviour of the primary tumour is needed to substantially improve our knowledge on the role of disseminated tumour cells in the complex process of tumour metastasis.

Bone marrow micrometastasis in breast cancer

BACKGROUND

Several studies have demonstrated that bone marrow micrometastasis in patients with breast cancer is an independent prognostic factor for systemic recurrence and poorer survival.

METHODS

This review describes the detection and clinical significance of micrometastatic cells in bone marrow, and examines the correlation between such micrometastasis and established clinicopathological prognostic factors. The relevant English language literature on bone marrow micrometastasis in breast cancer was searched via Medline (1975-2002), cross-referencing with key articles on the subject.

RESULTS AND CONCLUSION

The balance of evidence favours the hypothesis that bone marrow micrometastasis impacts on disease-free and overall survival. Further prospective studies are required to examine this in greater detail, with particular reference to early node-negative breast cancer and the value of adjuvant systemic therapy in patients with bone marrow micrometastasis.

Patterns of aneusomy for three chromosomes in individual cells from breast cancer tumors

Multi-color fluorescence in situ hybridization (FISH) can determine the changes in the copy numbers of several chromosomes simultaneously and can therefore be used to identify aneusomic patterns in individual cells. Aneusomic patterns may be useful for determining the malignant nature of rare epithelial cells in the blood of cancer patients. Touch preparations from 74 primary breast tumors were evaluated for aneusomy of chromosomes 1, 8 and 17 by tri-color-FISH. In the first part of the analysis, percentages of aneusomy for individual chromosomes and their combinations were determined. In the second part of the analysis, aneusomic patterns for these three chromosomes were analyzed in individual tumor cells and compared to aneusomic patterns observed in leukocytes and in individual cells from benign and normal breast tissue to determine aneusomic patterns indicative of malignancy. Ninety-two percentage of the primary breast carcinomas showed aneusomy for one or more enumerator probes. Comparison with benign breast tissue identified six aneusomic patterns in individual carcinoma cells indicative for malignancy by statistical analysis and not observed in leukocytes. Hence, certain patterns of aneusomy in individual cells involving chromosomes 1, 8 and 17 are indicative of malignancy in individual breast tumor cells and may be useful for determining malignancy of rare epithelial cells in the blood of breast cancer patients.

Differential display analysis of breast carcinoma cells enriched by immunomagnetic target cell selection: gene expression profiles in bone marrow target cells

The red bone marrow (BM) is an important indicator organ of hematogenous micrometastatic spread of carcinomas. Characterization of biological properties specific for BM micrometastatic cells, however, is technically challenging due to the limited number of target cells usually available for the purpose. This report provides referrals to qualitative gene expression profiling of BM micrometastatic cells enriched by immunomagnetic selection. First, an experimental strategy was used to study regulatory mechanisms involved when BM micrometastatic cells colonize distant organs. The MA-11 cells, originating from BM micrometastases in a breast cancer patient clinically devoid of overt metastatic disease, were injected into immunodeficient rats. Metastatic MA-11 cells were subsequently immunoselected from the resulting in vivo lesions. The selected cell populations were compared to the injected cells by differential display analysis, and several genes possibly involved in tumor cell invasion and proliferation were confirmed as differentially expressed among the various MA-11 cell populations. A direct approach to qualitative gene expression profiling of BM micrometastatic cells was also explored. Carcinoma cells were immunoselected from BM and axillary lymph nodes obtained from breast cancer patients, and the isolated cell populations were compared by differential display analysis. Two candidate genes, identified as factors involved in cellular growth control, appeared as differentially expressed by the target cells from BM. Our study provides detailed information on how to combine an immunomagnetic selection procedure and differential display analysis to reveal gene expression profiles that may characterize BM micrometastatic cells.

Immunobead-based detection and characterization of circulating tumor cells in melanoma patients

The presence of circulating tumor cells in bone marrow and peripheral blood of cancer patients may reflect the aggressiveness of the disease. This also applies to cancers that rarely give rise to overt bone marrow metastases. The clinical validity of micrometastasis detection for staging and prognostication depends on the sensitivity and reliability of the detection method. In malignant melanoma, most studies have used reverse transcriptase polymerase chain reaction (RT-PCR) techniques, commonly with tyrosinase mRNA as the target molecule. Unfortunately, highly inconsistent results have been reported, raising doubts about this approach. In a study of 81 melanoma patients with metastatic disease, we used an immunobead rosetting method in which live melanoma cells are selected and identified by binding of paramagnetic beads coated with the 9.2.27 antibody against the high molecular weight melanoma-associated antigen. In bone marrow samples obtained from 60 patients, 14 (23.3%) were positive, compared to only two of 81 in blood. A highly significant correlation (p = 0.0001, log rank test) was found between micrometastasis positivity and overall survival from time of removal of the primary tumor. Moreover, in regression analysis it was found that the presence of micrometastatic cells was an independent and the most important indicator of poor prognosis, with a relative risk of 5.38. The immunomagnetic method is simple, rapid, and highly sensitive and will be used in further prospective clinical studies.

Pitfalls in the detection of disseminated non-hematological tumor cells

There is not yet a consensus on the reliability of the methods that should be used for the detection of rare disseminated tumor cells from non-hematological malignancies. In this review, we will discuss the advantage and drawbacks of the classical approach of immunocytochemistry and the molecular detection by reverse transcriptase polymerase chain reaction (RT-PCR). The interpretation of the biological significance of circulating tumor cells and the pitfalls of the detection techniques are the main causes of discrepancy between the conclusions of different tumor-cell detection (TCD) studies.

Detection and clinical importance of micrometastatic disease

Metastatic relapse in patients with solid tumors is caused by systemic preoperative or perioperative dissemination of tumor cells. The presence of individual tumor cells in bone marrow and in peripheral blood can be detected by immunologic or molecular methods and is being regarded increasingly as a clinically relevant prognostic factor. Because the goal of adjuvant therapy is the eradication of occult micrometastatic tumor cells before metastatic disease becomes clinically evident, the early detection of micrometastases could identify the patients who are most (and least) likely to benefit from adjuvant therapy. In addition, more sensitive methods for detecting such cells should increase knowledge about the biologic mechanisms of metastasis and improve the diagnosis and treatment of micrometastatic disease. In contrast to solid metastatic tumors, micrometastatic tumor cells are appropriate targets for intravenously applied agents because macromolecules and immunocompetent effector cells should have access to the tumor cells. Because the majority of micrometastatic tumor cells may be nonproliferative (G0 phase), standard cytotoxic chemotherapies aimed at proliferating cells may be less effective, which might explain, in part, the failure of chemotherapy. Thus, adjuvant therapies that are aimed at dividing and quiescent cells, such as antibody-based therapies, are of considerable interest. From a literature search that used the databases MEDLINE(R), CANCERLIT(R), Biosis(R), Embase(R), and SciSearch(R), we discuss the current state of research on minimal residual cancer in patients with epithelial tumors and the diagnostic and clinical implications of these findings.