Quantitative Single-Cell Analysis of Isolated Cancer Cells with a Microwell Array.

The heterogeneous nature of tumor-cell populations suggests that quantitative analysis at the single-cell level may provide better insights into cancer biology. Specifically, detection of multiple biomarkers from a single cell offers important initial information about cellular behavior. However, conventional approaches limit biomarker detection at the single-cell level. Here, we fabricated a polymer microwell array to capture single cells from prostate-cancer cell lines and quantitatively analyzed the expression of three different cancer-related biomarkers, CD44, EpCAM, and PSMA, without a membrane protein-extraction step. The resulting information on cell-surface biomarker distributions was compared with that from other standard analytical techniques. Interestingly, a large variation in CD44-expression levels was observed when the cell-proliferation cycle was modulated. On the other hand, the expression levels of EpCAM in three different cell lines are consistent among the different analytical methods with the exception of the microarray, where it has a different substrate material to adhere to. This observation clearly emphasizes that biomarker choice and environmental control are critical for properly understanding the single-cell state.