Abstract 1939: The potentiality of capillary electrophoresis as a novel detection method for circulating tumor cells

Abstract Background: Circulating tumor cells (CTCs) are involved in metastasis, and detection of CTC has clinical utility as a biomarker for diagnosis of metastatic cancer patients. Therefore, detection of CTCs from blood is one of the most important approaches to identify metastatic cancer. However, the number of CTCs present in blood is considered less than a few hundred per mL of blood. Therefore, development of sensitive analytical method is required for CTC detection. We previously described a direct cell analysis method based on differences in cell surface charge using capillary electrophoresis (CE). In the present study, we investigate whether this analytical method can detect cancer cells in blood. Methods: We used the two human colorectal cancer cell lines (DLD-1 and SW480) and one pancreatic cancer cell line (BxPC-3), and blood sample from healthy donor as model samples. To prepare CTC model blood, cancer cells solution was added to blood sample. The stability of CTCs in blood was determined to analyze the model CTC samples after repetition of freeze-thawing. Capillary electrophoresis was performed at room temperature (ca. 25°C) using a linear polyacrylamide-coated fused silica capillary tube (50 cm × 75 μm i.d., effective length 9.5 cm), and 50 mM phosphate buffer (pH 6.8) was used as running buffer. The sample solution was introduced to the anodic end of the capillary with the hydrostatic introducing method (10 cm × 10 s). Results: Analysis of each sample revealed that peaks corresponding to cancer cells and blood cells were detected at different migration times. To clarify whether cancer cells in blood can be detected, we prepared CTC model blood by mixing cancer cell line and blood. We could successfully detect peaks corresponding to cancer cells in the blood separately from peaks corresponding to blood cells. These findings suggested that cancer cells can be distinguished from blood cells as cancer cell surfaces are more charged than blood cells. On the other hand, peak pattern of CTC model sample which repeated freeze-thawing was not different that of CTC model sample with non-freezing. This finding suggested that stored frozen blood samples might be useful for blood test to detect CTCs using this analytical method by CE. Conclusion: Therefore, direct cell analysis method using CE might be a potentially novel detection method for CTCs in blood. Citation Format: Tetsushi Yamamoto, Haruka Fukita, Risa Nishizawa, Kuniko Mitamura, Atsushi Taga. The potentiality of capillary electrophoresis as a novel detection method for circulating tumor cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 1939.