Single-cell analysis of tumors: Creating new value for molecular biomarker discovery of cancer stem cells and tumor-infiltrating immune cells

Figure 1 Single-cell analysis of cancer cells and cancer stem cells. A: Cancer cells, in particular CSCs, represent a complex process of invasion, EMT, shedding into the blood stream (intravasation), MET and invasion of circulating CSCs to the other tissues (extravasation); B: These CSCs can be isolated or also purified and enriched using different approaches based on their known molecular markers for variety of solid tumors or hematopoietic malignancies; C: Those enriched CSCs will be subjected to the single-cell based transcriptomic analysis. Upon sequencing, a pool of mapped reads will be analyzed based on the possible similarity to either sort the single cells to show how different cells are differentiated from more primitive ones, or will be sub-clustered according to their gene expression differences in order to dissect heterogeneous cell populations. CC: Cancer cell; CSC: Cancer stem cell; EMT: Epithelial-mesenchymal transition; MET: Mesenchymal-epithelial transition.

Figure 2 Main applications of single-cell based profiling in cancer research. A: Resolving intratumor heterogeneity; B: Finding and profiling CSCs within the bulk tumor; C: Tracing circulating CSCs; D: Study extravasation or intravasation and cell plasticity in invasive and metastatic cancer cells; E: Investigating clonal evolution in tumor cells based on their linage differentiation or mutational prevalence; F: Discovery the mechanism of therapy resistance at a single-cell level; G: Single-cell TCR sequencing of tumor-infiltrating lymphocyte. CC: Cancer cell; CSC: Cancer stem cell; EMT: Epithelial-mesenchymal transition; MET: Mesenchymal-epithelial transition; TCR: T cell receptor; TIL: Tumor-infiltrating lymphocyte.