Molecular pathogenesis of tumorigenesis caused by succinate dehydrogenase defect.

Succinate dehydrogenase (SDH), also named as complex II or succinate:quinone oxidoreductases (SQR) is a critical enzyme in bioenergetics and metabolism. This is because the enzyme is located at the intersection of oxidative phosphorylation and tricarboxylic acid cycle (TCA); the two major pathways involved in generating energy within cells. SDH is composed of 4 subunits and is assembled through a multi-step process with the aid of assembly factors. Not surprisingly malfunction of this enzyme has marked repercussions in metabolism leading to devastating tumors such as paraganglioma and pheochromocytoma. It is already known that mutations in the genes encoding subunits lead to tumorigenesis, but recent discoveries have indicated that mutations in the genes encoding the assembly factors also contribute to tumorigenesis. The mechanisms of pathogenesis of tumorigenesis have not been fully understood. However, a multitude of signaling pathways including succinate signaling was determined. We, here discuss how defective SDH may lead to tumor development at the molecular level and describe how yeast, as a model system, has contributed to understanding the molecular pathogenesis of tumorigenesis resulting from defective SDH.