Matrix: a complex amalgam of structures and functions in tumor microenvironment.

Cancer cells surrounded by a rich diversity of nonmalignant cell types are collectively embedded in the matrix, which is a dynamic, intricate three-dimensional mesh of biomolecules with both structural and functional properties. The matrix contains proteins, carbohydrates, and other glycoproteins that facilitate essential cellular communication and impact in various ways a broad spectrum of cellular functions, such as anchoring cells, guiding migration, and shaping signal gradients driving cell growth, apoptosis, survival, and differentiation. This review deals with the complexity of this amalgam of structures and functions and highlights the importance of the tumor microenvironment in the maintenance and evolution of tumors by describing certain bioactive macromolecules of the matrix, such as proteoglycans, hyaluronan, collagens, elastin, matricellular proteins as well as their cellular receptors like integrins and CD44.