[Identification and single-cell sequencing analysis of rare tumor cells in malignant pleural effusion of lung cancer patients].

Tumor heterogeneity refers to distinct genomic or phenotypic characteristics of tumor cells. Under the environmental or drug stress, tumor cells exhibit different responses, corresponding to different properties of cell proliferation, invasion, metastasis and drug resistance. In particular, a small fraction of tumor cells are capable of detaching from primary tumor sites and initiating distant metastases. Thus, tumor heterogeneity sets the basis for tumor resistance and metastasis. Traditional methods in studying tumor heterogeneity are mainly based on bulk cells from different locations in primary tumors, lacking analysis at the single-cell level and of metastatic tumor cells. This study establishes a single-cell method to study metastatic tumor cells in malignant pleural effusions of lung cancer patients. Metabolically active tumor cells in malignant pleural effusions are firstly identified with a metabolic marker 2-NBDG, a fluorescent glucose analog. These metabolically active tumor cells are confirmed to harbor the same driver oncogenic mutations by Sanger sequencing, followed by high-throughput sequencing to analyze copy number variation profiles. Our results show metastatic tumor cells in pleural effusion have the same driver mutations but different features in copy number variation patterns. The study provides new insights to understand the mechanism of tumor metastasis.

Fast isolation and ex vivo culture of circulating tumor cells from the peripheral blood of lung cancer patients.

Circulating tumor cells (CTCs) are free tumor cells shed from tumor site and enter into blood circulation. CTCs represent a reliable source of tumor cells for the molecular characteristics of the original tumor. However, the extraordinary rarity of CTCs makes the subsequent molecular and functional analysis technically challenging. Here, we describe a one-step microfludics-based immunomagnetic isolation method to isolate CTCs directly from the whole blood of lung adenocarcinoma patients. This method avoids harsh sample preparation and enrichment steps, and therefore preserves the viability (>90%) of CTCs during the in vitro isolation. The isolated CTCs are enriched in small volume (80 µL) and cultured ex vivo that leads to successful ex vivo expansion. The expanded CTCs can be frozen and thawed, which shows cell line property. Genetic sequencing on EGFR、KRAS、PIK3CA、TP53 and BRAF and metabolic assay (2-NBDG) are utilized to characterize the expanded CTCs. Our results demostrated that this method is suitable for ex vivo expansion of CTCs facilitates. The genomic, proteomic and metabolic analyses of CTCs have guiding significance in tumor precise treatment.