Figure 2.

Scheme of the sequential steps of cancer cell dissemination from primary tumor to distant metastases. EMT indicates the Epithelial-to-Mesenchymal Transition required for the gain of invasive properties and anoikis resistance. MET (Mesenchymal-to-Epithelial Transition) refers to the reversion to the epithelial phenotype at sites of metastatic tumor growth. The numbers indicate various strategies for studying the changes of DNA methylation in the multistep metastatic process. (1) DNA methylome and RNA expression profiling in metastatic tissues vs primary tumor specimens; (2) liquid biopsy: DNA methylome analysis in circulating tumor DNA (in cfDNA extracted from blood samples); (3) liquid biopsy: enrichment by microfluidics devices of (single vs clustered) CTCs from blood samples; (4) detection of EMT and cancer-stem-cell markers, by FACS analyses and cell sorting; (5) DNA methylome and RNA expression profiling in various CTC subpopulations (cancer-stem-cell assays: in vitro colonies and spheroids formation).