Hexokinase 2 detects cytokeratin negative circulating tumor cells in lung adenocarcinoma

Circulating tumor cells (CTCs) represent the molecular characteristics of tumor sites and travel in the blood for seeding distant metastases. "EpCAM+/pan-cytokeratin (CK)+/CD45-/DAPI+" has been widely accepted as a CTC definition, especially in breast cancer, prostate cancer and colorectal cancer. However, reports on CTC detection in non-small cell lung cancer are limited due to a lack of efficient CTC marker. We describe hexokinase 2 (HK2) that assays elevated glycolysis of cancer cells, called Warburg effect, as a new marker for CTC detection in lung adenocarcinoma (LUAD), especially the CK negative CTCs. Single-cell sequencing was used to confirm the malignancy of putative CTCs by detecting genome-wide copy number alternations characteristic of malignant cells. We employed this marker in a variety of liquid biopsies from LUAD patients, including peripheral blood, pleural effusion and cerebrospinal fluid.