Real-Time qPCR-Based Detection of Circulating Tumor Cells from Blood Samples of Adjuvant Breast Cancer Patients: A Preliminary Study.

BACKGROUND: Circulating tumor cells (CTCs) are cells that detach from a primary tumor, circulate through the blood stream and lymphatic vessels, and are considered to be the main reason for remote metastasis. Due to their origin, tumor cells have different gene expression levels than the surrounding blood cells. Therefore, they might be detectable in blood samples from breast cancer patients by real-time quantitative polymerase chain reaction (RT-qPCR). MATERIALS AND METHODS: Blood samples of healthy donors and adjuvant breast cancer patients were withdrawn and the cell fraction containing white blood cells and tumor cells was enriched by density gradient centrifugation. RNA was isolated and reverse transcribed to cDNA, which was then used in TaqMan real-time PCR against cytokeratin (CK)8, CK18 and CK19. 18S and GAPDH were used as controls. RESULTS: All 3 CKs were, on average, found to be significantly higher expressed in adjuvant breast cancer samples compared to negative controls, probably due to the presence of CTCs. Unfortunately, gene expression levels could not be correlated to tumor characteristics. CONCLUSIONS: RT-qPCR could make up a new approach for the detection of CTCs from blood samples of breast cancer patients, but a correlation of the PCR data to gold standard methods in CTC detection would help to further improve the informative value of the qPCR results.

Detection of breast cancer cells in blood samples by immunostaining of the Thomsen-Friedenreich antigen.

AIM: Disseminated tumor cells are found in the bone marrow of patients with epithelial carcinoma and are correlated with a poor prognosis of the disease. Their detection is a technical challenge. This report describes a model system for the detection of cancer cells by co-immunostaining of Thomsen-Friedenreich and Her-2 antigens. METHODS & RESULTS: Small numbers of cancer cells from different cancer cell lines were mixed with blood samples of healthy donors. Cytospins were prepared and double immunostaining against Thomsen-Friedenreich antigen and Her-2 was carried out by fluorochrome-coupled antibodies. Quantification of Thomsen-Friedenreich and/or Her-2-positive cells was performed with an epifluorescence microscope. On average, 83% of cancer cells were recovered by this method. CONCLUSION: Immunostaining is a useful method for the detection of cancer cells in blood samples. Results of this model system will be transferred to bone marrow patient samples to prove the benefits for detection of disseminated tumor cells.

Detection of circulating tumour cells on mRNA levels with established breast cancer cell lines.

Circulating tumour cells were detected and quantified by real-time polymerase chain reaction (PCR) in peripheral blood, based on the fact that the expression of certain genes is upregulated in tumour tissues in comparison to surrounding blood cells. Calibration curves showing gene expression as functions of the number of tumour cells within a blood sample were prepared. Blood samples were therefore spiked with cells of breast cancer cell lines, RNA was extracted, transcribed to complementary DNA (cDNA) and used in real-time PCR reaction on the Cytokeratins (CK) 8, 18 and 19. Calibration curves were generated by Microsoft™ Excel®. Relative quantification curves of gene expression in different breast cancer cell lines showed no unitary tendencies. The oscillations in the relative quantification curves of gene expression suggested an occurrence of immunological effects, leading to an apparent agglutination of added tumour cells together with the blood cells of the sample. Thus, strategies to obtain evaluable results should be considered.

Quantification of breast cancer cells in peripheral blood samples by real-time rt-PCR.

BACKGROUND: Circulating tumour cells (CTCs) are cells that have detached from a primary tumour, circulate in the peripheral blood, and are considered to be the main root of distant metastases. We present a method for the detection of CTCs by real-time PCR on different cytokeratin markers. MATERIALS AND METHODS: Blood samples of a healthy donor were mixed with specific numbers of cells from different breast carcinoma cell line cells. RNA was isolated from the samples and transcribed into cDNA. TaqMan real-time PCR for cytokeratins 8, 18 and 19 was carried out and was correlated to that of 18S. RESULTS: Cytokeratin gene expression increased in all samples, when as few as 10 tumour cells were added. In the CAMA-1 cell line, the increase was even greater the more cells were added. CONCLUSION: By this methodology, cells from mammary carcinoma cell lines can be detected in blood samples. Its benefit will be validated in samples from patients with breast cancer.