Relevance of circulating tumor cells, extracellular nucleic acids, and exosomes in breast cancer

Abstract

Early detection of cancer is vital to improved overall survival rates. At present, evidence is accumulating for the clinical value of detecting occult tumor cells in peripheral blood, plasma, and serum specimens from cancer patients. Both molecular and cellular approaches, which differ in sensitivity and specificity, have been used for such means. Circulating tumor cells and extracellular nucleic acids have been detected within blood, plasma, and sera of cancer patients. As the presence of malignant tumors are clinically determined and/or confirmed upon biopsy procurement-which in itself may have detrimental effects in terms of stimulating cancer progression/metastases-minimally invasive methods would be highly advantageous to the diagnosis and prognosis of breast cancer and the subsequent tailoring of targeted treatments for individuals, if reliable panels of biomarkers suitable for such an approach exist. Herein, we review the current advances made in the detection of such circulating tumor cells and nucleic acids, with particular emphasis on extracellular nucleic acids, specifically extracellular mRNAs and discuss their clinical relevance.

Neuromedin U: A Candidate Biomarker and Therapeutic Target to Predict and Overcome Resistance to HER-Tyrosine Kinase Inhibitors

“…This observation reflected that of the cells themselves. This is in keeping with our previous observations from a range of cell lines (16,17,19) and pilot study analysis of serum and corresponding tumor tissue from patients with breast cancer (18). These findings indicate that full-length mRNAs can be selectively expelled from cells.…”

“…Predictive biomarkers for HER-targeting drugs (ideally extracellular, minimally invasive) are needed for improved patient selection and thus enhanced patient outcome, as are novel therapeutic strategies to circumvent resistance. Our previous studies indicate that analyzing extracellular RNAs in medium conditioned by cells can be a useful starting point to identifying potential biomarkers, some proving to have functional relevance within the cell (16)(17)(18)(19)(20).…”

Microvesicles Released from Human Renal Cancer Stem Cells Stimulate Angiogenesis and Formation of Lung Premetastatic Niche

“…Indeed, CD105 þ MVs contained proangiogenic mRNAs and miRNAs that may be involved in tumor progression and metastases. Recently, circulating MVs were described in patients with various tumors (27)(28)(29)(30)(31)(32), suggesting that they may serve as a diagnostic and prognostic tool (33)(34)(35). In the context of cancer, several studies pointed out the potential role of tumor-derived MVs in the interaction with stromal cells and in the formation of premetastatic niche (36)(37)(38)(39).…”

Proteomic Analysis of Two Types of Exosomes in Human Whole Saliva

“…Recent studies show that exosomes are attractive biomarker candidates for diseases such as cancer. [18][19][20] In a previous study, we have isolated exosomes from human whole saliva through gel-filtration, and found that dipeptidyl peptidase IV (DPP IV), actin, polymeric immunoglobulin receptor (pIgR), immunoglobulin A (IgA) and galectin-3 were associated with exosomes. 15) However, detailed analysis of the protein composition was not performed.…”