Evaluation of a Panel of Tumor Markers for Molecular Detection of Circulating Cancer Cells in Women with Suspected Breast Cancer

Detection of Mammaglobin A-mRNA-positive circulating tumor cells in peripheral blood of patients with operable breast cancer with nested RT-PCR

OBJECTIVES

The development and validation of a nested RT-PCR methodology for the detection of Mammaglobin A-mRNA-positive circulating tumor cells in peripheral blood of patients with operable breast cancer and evaluation of its prognostic significance.

DESIGN AND METHODS

Different combinations of specific primers were in silico designed and selected, so that false positive results due to genomic DNA contamination were avoided. The specificity of the primers used was evaluated in 30 healthy individuals, 20 patients with colorectal cancer and 20 patients with non-small cell lung cancer. The method was applied in 101 patients with operable breast cancer before the administration of adjuvant chemotherapy and 39 patients with metastatic breast cancer.

RESULTS

Mammaglobin A-mRNA-positive cells were detected in 14/101 (13.9%) of early breast cancer patients but not in the control population studied (0%); 9 of them (64.3%) relapsed during the follow-up period. Mammaglobin A was detected in 7/39 (17.9%) of patients with verified metastasis. Multivariate analysis revealed the detection of Mammaglobin A-mRNA-positive cells, as an independent risk factor for reduced DFI.

CONCLUSIONS

Mammaglobin A is a highly specific molecular marker for the detection of circulating tumor cells in operable breast cancer, with important prognostic applications.

Development of a high-throughput membrane-array method for molecular diagnosis of circulating tumor cells in patients with gastric cancers

Recently several noninvasive methods have been employed to detect circulating tumor cells (CTCs) in cancer patients. In this study, we have developed a highly sensitive, high-throughput colorimetric membrane-array method that was designed to detect a panel of mRNA markers including human telomerase reverse transcriptase (hTERT), cytrokeratin-19 (CK-19), carcinoembryonic antigen (CEA) and mucin 1 (MUC1) mRNA for the presence of CTCs in the peripheral blood of patients with gastric cancer (GC). Digoxigenin-labeled cDNA targets synthesized following total RNA isolation from peripheral blood samples of 64 GC patients and 80 healthy individuals were subjected to membrane-array hybridization. The results showed that membrane array could positively detect 5 cancer cells/ml of peripheral blood in GC cell-dilution experiments. The sensitivity, specificity and diagnostic accuracy for hTERT, CK-19, CEA and MUC1 mRNA ranged from 78.1% to 82.8%, 76.3% to 85% and 81.3% to 83.3%, respectively. Both CEA and MUC1 mRNA expression was correlated significantly with all malignant biological properties of GC, such as macroscopic type, depth of tumor invasion, lymph-node metastasis, TNM stage and coexisting distant metastasis (all p < 0.05). Using these 4 markers in combination, the sensitivity, specificity and diagnostic accuracy of membrane array were raised to 89.1%, 91.3% and 90.3%, respectively. The expression of all 4 mRNA markers was an independent predictor for postoperative recurrence/metastasis. GC patients with the expression of all the 4 mRNA markers showed a poorer survival rate than those without the expression of any 1 mRNA marker (p = 0.0223). These findings demonstrated that our membrane-array method could detect CTCs in the circulation of GC patients with considerably high sensitivity and specificity. The identification of CTCs in the peripheral blood may be useful in the auxiliary cancer diagnostics or postoperative surveillance of GC patients for recurrence/metastasis.

Tumor cell detection in peripheral blood and bone marrow

PURPOSE OF REVIEW

Whether the occurrence of tumor cells in peripheral blood or bone marrow from patients with solid tumors is predictive for disease recurrence or of any other prognostic relevance remains unknown. This article reviews recently published results focusing on the various methods used, their correlations with clinical or biological parameters and their potential prognostic value.

RECENT FINDINGS

An increasing number of marker genes and different techniques, alone or in combinations, have been used for the detection of tumor cells in peripheral blood and bone marrow. Various results obtained are hardly comparable, most often due to the different methods in use. The frequency of circulating tumor cells in peripheral blood varied within a broad range and their clinical relevance appeared to be contradictory, at least in part. Disseminated tumor cells in bone marrow reached an independent prognostic value in breast cancer patients, but several investigations led to inconsistent correlations with clinical or prognostic criteria.

SUMMARY

Still many questions remain unanswered; hence, the detection of tumor cells in peripheral blood or bone marrow cannot yet be taken into account for therapeutic decisions.

Clinical significance of MUC1 and c-Met RT-PCR detection of circulating tumor cells in patients with gastric carcinoma

BACKGROUND

Recently, several reverse transcription-polymerase chain reaction (RT-PCR) techniques have been proven to be useful in the detection of circulating tumor cells (CTCs) in cancer patients. We attempted to detect CTCs in patients with gastric cancer (GC) using a RT-PCR assay for c-Met and MUC1 and to evaluate their clinical value.

METHODS

Using a RT-PCR assay, c-Met and MUC1 mRNAs were amplified in 52 GC patients and 36 healthy individuals. Analyses were carried out for their correlation with the patients' clinicopathologic features, the occurrence of new post-operative metastasis, as well as the overall survival rates.

RESULTS

In the RT-PCR analysis of peripheral blood, 61.5% (32/52) and 71.2% (37/52) of GC patients were positive for c-Met and MUC1 mRNA, respectively. The sensitivity and specificity of either mRNA detected in peripheral blood is 82.7% and 86.1%, respectively, with an accuracy of 84.1%. The detection of c-Met or MUC1 mRNA was significantly correlated with the depth of tumor invasion, lymph node metastases, TNM stage, vessel invasion, perineural involvement, and post-operative metastasis (all P<0.05). Kaplan-Meier analysis demonstrated that the overall survival rate of patients with positive c-Met or MUC1 mRNA expression in the peripheral blood was significantly shorter than in patients negative for c-Met or MUC1 mRNA expression (both P<0.05).

CONCLUSIONS

Our findings suggest that using RT-PCR for the detection of c-Met or MUC1 mRNA may be a promising tool for the early detection of micro-metastatic CTCs in GC patients. Combination of these 2 tumor-specific mRNA markers would increase the detection rate and may be clinically helpful in predicting the outcome in GC patients.

Development of a membrane array-based multimarker assay for detection of circulating cancer cells in patients with non-small cell lung cancer

Combination of multiple mRNA markers has been largely investigated for detection of circulating cancer cells. However, current PCR-based methods are relatively expensive and time consuming. The aim of this study was to develop a membrane array-based multimarker assay for detection of circulating cancer cells in nonsmall cell lung cancer (NSCLC) patients. At first, we selected 22 candidate genes by means of suppression subtractive hybridization and Northern blot analysis. The diagnostic value of each candidate gene was then preliminarily evaluated in 50 pairs of blood samples by membrane array method. Accordingly, 17 genes with area under the ROC curve (AUC) > or = 0.8 were selected as target genes to reconstruct the diagnostic membrane array, which was then used to test peripheral blood samples from 100 NSCLC patients and 147 control subjects. ROC curve analysis demonstrated that the optimal threshold number of overexpressed markers on membrane array for discrimination between NSCLC patients and control subjects was 12. As a result, the diagnostic membrane array could detect circulating cancer cells in 90 (90%) of 100 NSCLC patients and in 14 (9.5%) of 147 control subjects (including 6 of 100 normal persons, 3 of 20 breast cancer patients, 3 of 15 colorectal cancer patients and 2 of 12 gastric cancer patients). Moreover, the detection rate was significantly correlated with NSCLC patients' metastatic status and overall stage (p = 0.028 and 0.014, respectively). These results suggested that our blood-based membrane array assay for molecular detection of circulating lung cancer cells has great potential for clinical applications.

Simultaneous detection of multiple mRNA markers CK19, CEA, c-Met, Her2/neu and hMAM with membrane array, an innovative technique with a great potential for breast cancer diagnosis

The objective of this study was mainly to develop and evaluate a membrane array-based method simultaneously detecting the expression levels of a multiple mRNA marker panel in the peripheral blood for used in complementary breast cancer diagnosis. The mRNA markers employed included cytokeratin 19 (CK-19), carcinoembryonic antigen (CEA), c-Met, Her2/neu, and mammaglobin (hMAM). The specimens of peripheral blood were collected from 80 healthy women and 102 female patients with breast cancer. The expression levels of molecular markers were evaluated by real-time Q-PCR and membrane array. Data obtained from real-time Q-PCR and membrane array were subjected to linear regression analysis, revealing that there was a high degree of correlation between the results of these two methods (r=0.979, P<0.0001). The result of membrane array assay with a combined panel of five mRNA markers was demonstrated to achieve sensitivity of 80.6%, and specificity of 83.8% for breast cancer detection, much higher than those of analysis of single marker. In addition, we demonstrated that the membrane array method could detect circulating cancer cells at a density as low as five cancer cells per 1 ml of blood. The analysis of correlation between the outcome of membrane array and clinicopathological characteristics indicated that overexpression of the multiple marker panel was significantly correlated with tumor size (P=0.030) and TNM stage (0.009). In conclusion, the detection of circulating cancer cells by means of membrane array simultaneously monitoring five mRNA markers could significantly enhance the sensitivity and specificity for cancer cell detection.

Genomics and circulating tumor cells: promising tools for choosing and monitoring adjuvant therapy in patients with early breast cancer?

PURPOSE OF REVIEW

Gene expression profiling using a class discovery approach has consistently shown that breast cancer emerges as a group of different disease entities: the basal-like, the human epidermal growth factor receptor 2 type, the normal breast-like, and at least two different hormone receptor positive or luminal types. Initial reports have also suggested that certain expression patterns are associated with relapse. Current data on adjuvant therapy are only beginning to consider this biologic heterogeneity (estrogen receptor and human epidermal growth factor receptor 2 status). Similarly, the search for isolated tumor cells in blood or bone marrow has been regarded as another approach for defining prognosis and tailoring adjuvant therapies. The purpose of this review is to highlight the recent data emerging from both approaches as a means of assessing prognosis and tailoring therapy in patients with early breast cancer.

RECENT FINDINGS

The initial reports on prognosis assessment of breast cancer using the expression profile have been corroborated, but the differences between the actual genes selected for the different prognostic signatures remain difficult to explain. Others have introduced added signatures, such as those associated with proliferation or with wound healing, or selected subgroups on the basis of, for example, estrogen receptor level prior to class comparison. The data on the quantification of expression of a limited number of selected genes are promising for both prognosis and prediction. The segregation of histological grade 2 tumors into genetically defined grade 1 or 3 tumors and its associated prognostic significance is a critical observation. The standardization of methods for measuring isolated tumor cells in blood or bone marrow has resulted in validated data both on prognosis in early breast cancer and in the advanced setting. Methylation of circulating DNA might become another method for selecting patients for extended adjuvant regimens.

SUMMARY

The new molecular knowledge must be incorporated into prospective clinical studies in patients with early breast cancer. This is the challenge for the years to come.