Up to date, novel tools for low-cost, minimal invasive cancer surveillance, cancer screening and treatment monitoring are in urgent need. Physicians consider the socalled liquid biopsy as a possible future tool successfully achieving these ultimate goals. Here, we aimed to identify circulating tumour-associated MPs (taMPs) that could aid in diagnosing minimal-invasively the presence and follow up treatment in non-small cell lung carcinoma (NSCLC), colorectal carcinoma (CRC) and pancreas carcinoma (PaCa). Tumour-associated MPs (taMPs) were quantified after isolation by centrifugation followed by flow cytometry analysis from the serum of cancer patients with CRC (n = 52), NSCLC (n = 40) and PaCa (n = 11). Healthy subjects (n = 55) or patients with struma nodosa (thyroid nodules) (n = 43) served as negative controls. In all three types of tumour entities, the presence of tumour was associated with an increase of circulating EpCAM Oncotarget 30868 www.impactjournals.com/oncotarget apoptosis and that are released into the extracellular space. MPs can be isolated from human fluids such as whole blood, plasma, serum or e.g. synovial fluid [1][2][3][4][5][6]. They carry the surface signature of their cell of origin and the quantification of MP subsets using FACS sorting permits a non-invasive assessment of cell specific pathologies, especially in inflammation [7][8][9][10]. MPs have to be differentiated and separated from exosomes, which are derived from intracellular vesicles and do not carry cell surface markers of their origin, and from the larger fragments of apoptotic bodies [2,3]. So far, only a few and technically limited studies have been performed on putative cancer-derived MPs or microvesicles identified by single surface marker [11][12][13]. Therefore, we explored the diagnostic potential of tumour-associated MPs (taMPs) and MP subtypes in thoroughly characterised patients with various underlying cancer entities such as colorectal carcinoma, non-small cell lung carcinoma and pancreas carcinoma.
RESULTS
Patients with CRC, other neoplasia or thyroid nodules (struma nodosa) show characteristic MP profilesBased on literature research various cancer markers were considered for the detection of taMPs expressing common cancer antigens as EpCAM and CD147. Corresponding cancer lines were screened for the chosen surface antigens (data not shown). Indeed, EpCAM and CD147 were identified on the surface of cancer cell lines of colorectal (CRC), lung (NSCLC) and pancreas (PaCa) (data not shown). MPs were isolated by differential centrifugation of sera of total 103 confirmed cancer patients. Median EpCAM + taMPs values were significantly elevated (oneway ANOVA) in patients with CRC (n = 52), NSCLC (n = 40), PaCa (n = 11) by an average of 2.3 fold irrespective of the tumour entity and size ( Figure 1A and Table 1). Surprisingly, EpCAM + taMPs were also found elevated in thyroid nodules patients (short: struma, n = 40) as compared to healthy controls by 1.9 fold (p < 0.05). Nevertheless, the antigen combination of EpC...