mRNA and microRNA Expression Profiles in Circulating Tumor Cells and Primary Tumors of Metastatic Breast Cancer Patients

Abstract

Purpose: Molecular characterization of circulating tumor cells (CTC) holds great promise. Unfortunately, routinely isolated CTC fractions currently still contain contaminating leukocytes, which makes CTC-specific molecular characterization extremely challenging. In this study, we determined mRNA and microRNA (miRNA) expression of potentially CTC-specific genes that are considered to be clinically relevant in breast cancer.Experimental Design: CTCs were isolated with the epithelial cell adhesion molecule-based CellSearch Profile Kit. Selected genes were measured by real-time reverse transcriptase PCR in CTCs of 50 metastatic breast cancer patients collected before starting first-line systemic therapy in blood from 53 healthy blood donors (HBD) and in primary tumors of 8 of the patients. The molecular profiles were associated with CTC counts and clinical parameters and compared with the profiles generated from the corresponding primary tumors.Results: We identified 55 mRNAs and 10 miRNAs more abundantly expressed in samples from 32 patients with at least 5 CTCs in 7.5 mL of blood compared with samples from 9 patients without detectable CTCs and HBDs. Clustering analysis resulted in 4 different patient clusters characterized by 5 distinct gene clusters. Twice the number of patients from cluster 2 to 4 had developed both visceral and nonvisceral metastases. Comparing transcript levels in CTCs with those measured in corresponding primary tumors showed clinically relevant discrepancies in estrogen receptor and HER2 levels.Conclusions: Our study shows that molecular profiling of low numbers of CTCs in a high background of leukocytes is feasible and shows promise for further studies on the clinical relevance of molecular characterization of CTCs.

Regulation of the MicroRNA 200b (miRNA-200b) by Transcriptional Regulators PEA3 and ELK-1 Protein Affects Expression of Pin1 Protein to Control Anoikis

“…In this study, suspension-cultured MCF-7 cells decreased the expression of miRNA-200b, which further increased the expression of Pin1 and decreased the expression of cyclin D1. Furthermore, it has been reported that the expression of miRNA-200b depends on the stage of metastasis (58), and it has been reported that, in metastatic breast cancer patients, the expression level of miRNA-200b in circulating tumor cells was lower than in whole blood (59). Taken together, we hypothesize that losing interaction with the matrix could decrease the expression of miRNA200b, resulting in inhibition of proliferation and resistance to apoptosis.…”

Gene expression markers in circulating tumor cells may predict bone metastasis and response to hormonal treatment in breast cancer

“…These cells have been detected in patients with metastatic disease, as well as in those whose tumors are apparently localized. The identification and characterization of such cells and the determination of their clinical significance have attracted attention in the field of cancer research (3)(4)(5).…”

Emerging techniques in molecular detection of circulating tumor cells

“…Profiled by TaqMan human miRNA microarrays, plasma of CTC-positive metastatic breast cancer patients were found to have significantly higher level of miR-200b than CTC-negative metastatic breast cancer [21]. Another study also identified 10 miRNAs that were more abundantly expressed in samples from breast cancer patients with at least five CTCs in 7.5 ml of blood compared with samples from patients without detectable CTCs [22]. These studies show that miRNA profiling of low numbers of CTCs in a high background of leukocytes is feasible.…”