Cancer progression: a single cell perspective

Tumor tissues are constituted by a dynamic diversity of malignant and non-malignant cells, which shape a puzzling biological ecosystem affecting cancer biology and response to treatments. Over the course of the tumoral disease, cancer cells acquire genotypic and phenotypic changes, allowing them to improve cellular fitness and overcome environmental and treatment constraints. This progression is depicted by an evolutionary process in which single cells expand as a result of an interaction between single-cell changes and the local microenvironment. Recent technological developments have made it possible to depict the development of cancer at the single-cell level, offering a novel method for understanding the biology of this complex disease. Here, we review those complex interactions from the perspective of single cells and introduce the concept of omics for single-cell studies. This review emphasizes the evolutionary dynamics that control cancer progression and the capacity of single cells to escape the local environment and colonize distant sites. We are assisting a rapid progression of studies carried out at the single-cell level, and we survey relevant single-cell technologies looking at multi-omics studies. These forefront approaches will address the combined contribution of both genetic and non-genetic factors to cancer progression and will pave the path for precision medicine in cancer.