Biochemistry of Cell Invasion

Introduction

Cell invasion is a complex process involving the entry of cells into tissues or organs where they are not normally present. This process is crucial for various biological events, such as embryonic development, immune response, and cancer metastasis. Understanding the biochemistry of cell invasion is essential for developing therapeutic strategies to target invasive cells.

Cell Adhesion Molecules

Cell invasion begins with the interaction of cells with the extracellular matrix (ECM) through cell adhesion molecules (CAMs). CAMs such as integrins, cadherins, and selectins play a crucial role in mediating cell-ECM and cell-cell interactions. Integrins are transmembrane receptors that bind to specific ECM proteins, providing a physical link between the cell and its extracellular environment. Cadherins are calcium-dependent adhesion molecules that mediate cell-cell adhesion, while selectins are involved in the recruitment of leukocytes to sites of inflammation.

Proteolytic Enzymes

Proteolytic enzymes, such as matrix metalloproteinases (MMPs) and serine proteases, play a key role in cell invasion by degrading the ECM and basement membrane. MMPs are a family of zinc-dependent endopeptidases that can cleave various components of the ECM, including collagen, laminin, and fibronectin. Serine proteases, such as urokinase-type plasminogen activator (uPA) and tissue-type plasminogen activator (tPA), are involved in the activation of pro-MMPs and the degradation of ECM proteins.

Signaling Pathways

Several signaling pathways regulate cell invasion, including the PI3K/Akt, MAPK, and Wnt signaling pathways. These pathways control various cellular processes, such as cell proliferation, migration, and survival. The PI3K/Akt pathway promotes cell invasion by regulating the expression of MMPs and inhibiting apoptosis. The MAPK pathway mediates cell migration and invasion by regulating the expression of genes involved in cell adhesion and cytoskeletal reorganization. The Wnt pathway plays a crucial role in cell invasion by promoting epithelial-mesenchymal transition (EMT) and metastasis.