Final answer:
Cancer-associated fibroblasts (CAFs) are modified fibroblasts that contribute to the tumor microenvironment by secreting abnormal ECM components and aiding in tumor growth and invasiveness, with focal adhesion kinase (FAK) playing a critical role in their transformation and function.
Step-by-step explanation:
Cancer-associated fibroblasts (CAFs) are a key component in the tumor microenvironment. These cells, which are a modified version of fibroblasts, actively secrete various components that contribute to the extracellular matrix (ECM), influencing tumor growth and progression. Regular fibroblasts provide structure and support in connective tissues by secreting proteins and polysaccharides, but when they transform into CAFs, they start to secrete abnormal levels of ECM proteins, growth factors, and cytokines, creating a favorable environment for cancer cells to thrive.
One crucial player in the transformation of normal fibroblasts into CAFs is the focal adhesion kinase (FAK), which is often found upregulated in various cancers such as colon, breast, and thyroid cancer. FAK is an integral part of integrin-mediated signal transduction, a process that facilitates cell adhesion to the ECM, and is also known to interact with tumor suppressor p53. When FAK is overexpressed, it can aid in tumorigenesis by disrupting the normal regulation of cell-cell and cell-ECM adhesion, thus promoting tumor invasiveness and metastasis.