Matrix metalloproteinases in pituitary adenoma invasiveness

Pituitary adenomas (PA) are the most common lesions of hypothalamic-pituitary region. Clinical presentations of PA depend on both hormonal activity and tumor growth characteristics. Despite the fact that PA are mostly benign, they can grow invasively and mechanically affect adjacent structures. With invasive growth of PA, radical removal is difficult and associated with a higher risk of surgical complications. Pathogenesis of PA invasiveness is not fully understood. Tumor cell invasion depends on both intercellular interactions within the tumor and interaction with extracellular matrix components (ECM). Major factors that play an important role in these processes include matrix metalloproteinase (MMP) family and tissue inhibitors of matrix metalloproteinases (TIMPs). Two MMPs were mostly studied in PA - types 2 and 9. These molecules are of interest, as they participate in degradation of type IV collagen, which is a key component of the ECM in hypothalamic-pituitary region. This review discusses the general concept of PA invasiveness, the characteristics of MMPs, and research of the relationship between these molecules and PA invasiveness.