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Hydration forces are ubiquitous in nature and technology. Yet, the characterization of interfacial hydration structures and their dependence on the nature of the substrate and the presence of ions have...

BACKGROUND: Mutations in the KRAS oncogene occur in 30-60% of the patients with colorectal cancer (CRC). Constitutively activation of the KRAS protein leads to growth, proliferation, and survival of CRC cells. KRAS mutation is an early event during colorectal carcinogenesis, therefore all tumor cells including metastatic cells are expected to have the same mutation status. We investigated the KRAS mutation status in primaries and metastatic tissue of patients with liver and lung metastasis. METHODS: Patients with histological confirmed CRC who underwent surgical resection of the primary tumor and biopsy or surgical resection of the corresponding liver (n = 304) or lung metastasis (n = 90) were included. KRAS mutation analysis was performed for codons 12 and 13 using sequencing analysis. We used Next Generation Sequencing (NGS) to further evaluate a patient with a discordance in KRAS mutation status between the primary and metastasis. RESULTS: KRAS mutations were detected in 35.3% of the 304 primary tumors with liver metastases. In 11 cases (3.6%), we found a discordance between primary tumor and metastasis: 5 primary tumors had a KRAS mutation with a wild-type metastasis, 1 primary tumor was wild type with a KRAS mutation in the metastasis, and in 5 cases the primary tumor and the metastasis had a different KRAS mutation. NGS of the patient with a wild type primary tumor and a KRAS mutation in the liver metastases revealed a KRAS mutation in 7.5% of the primary tumor cells. KRAS mutations were detected in 46.7% of the 90 primary tumors with lung metastases. The KRAS mutation frequency in lung metastases was 55.6%. A discordance in KRAS mutation status between primary tumors and metastasis was observed in 8 cases (8.9%). In all these patients the primary tumors had a KRAS wild-type while the lung metastasis showed a KRAS mutation. CONCLUSION: We observed a higher KRAS mutation frequency in primary CRC with lung metastases compared to primary CRC with liver metastases (p=0.038). Increased discordance in the lung metastases might indicate that these originate in very small subclones of the primary. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 432. doi:1538-7445.AM2012-432

Purpose: The FDA cleared CellSearch assay for enumeration of Circulating Tumor Cells (CTC) detects CTC by fluorescence microscopy after immunomagnetic enrichment targeting Epithelial Cell Adhesion Molecule (EpCAM). The system generated thumbnail images of DNA+, Cytokeratin+ (CK+) events and presents these to a reviewer for scoring events as CTC. An event is a CTC when it is negative for CD45, positive for DNA and CK and is larger than a 4 × 4 μm2 with a cell-like morphology. The presence of CTC defined in such manner is strongly associated with poor outcome. The question arises whether and how many other tumor cells are present in the blood that do not have the phenotype defined by the CellSearch system. In this study we investigated the number of cells that are obtained after EpCAM enrichment and immunofluorescent labeling by CellSearch that could not be assigned to a cell lineage and explored the addition of other markers to increase the number of cells that could be assigned to a cell lineage. Methods: Automated image analysis was used to reanalyze archived CellSearch images of 12572 patient samples with benign breast and colorectal disease, non-metastatic breast and colorectal cancer, metastatic colorectal and prostate cancer. For the evaluation of additional markers blood from healthy volunteers aged 20-55 were used. For the evaluation of CD16-PerCP as an additional leukocyte marker, blood from 30 patients with metastatic lung cancer was used. Results: The median number of DNA+CK− cells found was 450 of which only 155 (34%) were identified as leukocytes (CD45-APC+). The number of DNA+CK− was higher in patients with metastatic disease as compared to those with non-metastatic or benign disease (median 2028 vs 293). The proportion of identified leukocytes (DNA+CK−CD45+) was however only slightly lower (median 35% vs 43%). The number of DNA+CK−CD45− cells was larger in patients with more CTC (0 CTC: 495, 1-10 CTC: 2024, 11-100 CTC: 8140, >100 CTC: 8983). The number of DNA+CK− cells also increased with aging of the blood samples, but did not account for the observed differences. The use of both CD16 and CD45 decreased the number of DNA+CK− cells and increased the fraction of cells identified as leukocytes to 90% in healthy donors and 78% in lung cancer patients. Conclusion: A large proportion of nucleated cells obtained after EpCAM enrichment is not accounted for. The majority of these cells are leukocytes not detected with the current reagents and microscope of the CellSearch system. The correlation between DNA+CK−CD45− cells and increasing number of CTC suggests an association with cancer and warrants further investigation. Citation Format: Guus van Dalum, Simone van Lin, Ana M.C. Barradas, Jeroen T.N. Hiltermann, Harry J.M. Groen, Leon W.M.M. Terstappen. The identity of all nucleated cells enriched by CellSearch. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 389. doi:10.1158/1538-7445.AM2015-389