Utility of microsieve device for enumeration and miRNA expression profiling of CTCs for personalized cancer management.

Abstract

e22107 Background: Although a rare peripheral cell population, circulating tumor cells (CTCs) represent a potential alternative to serial invasive biopsies as a source of tissue in monitoring clinical states of non-hematological malignancies. CTCs harvested from a single patient are a heterogeneous mixture of cells differing in their transcriptome expressional profiles, metastatic potential and drug resistance properties. Mere identification and enumeration of CTCs are unable to provide qualitative information about individual CTC biology. The presence of a few highly malignant, metastasis-capable CTCs and cancer stem cells among the other less aggressive CTCs in the circulating population will not be apparent from CTC counts alone. Methods: We developed a high-throughput size-exclusion microsieve device (CellSievo, Singapore) to isolate CTCs (defined as DAPI-positive, CD45-negative cells), regardless of the cell surface receptors expressed, from 74 breast cancer patients. Using CTCs eluted from the microsieve post-capture, we performed microRNA expression profiling to further characterize breast cancer CTCs. Results: Using CellSievo’s microsieve device, we obtained an average mean CTC count of 21.2 (+/- 31.8; range=0-112.5) per 7.5ml peripheral blood, for breast cancer patients, as opposed to 1.3 (+/-1.6, range 0-5.0) for healthy subjects. Viable CTCs from breast cancer patients were successfully harvested for downstream microRNA profiling. CTCs from breast cancer patients were routinely found to express microRNA profiles mediating epithelial-to-mesenchymal transition, tumor invasion, and regulation of chemotherapeutic drug resistance to tamoxifen, anthracyclines, taxanes, and trastuzumab. Serial monitoring of microRNA expression pattern of CTCs could identify emergence of novel tumor populations with distinct microRNA expression patterns during or after anticancer therapy (detailed microRNA expression data to be presented). Conclusions: Our results suggest that microRNA biomarkers derived from peripheral CTCs can yield highly useful information and offer prognostic and predictive applications for therapeutics and companion diagnostic development.