New Roles for Glycogen in Tumor Progression.

Glycogen is a high-density glucose polymer, which provides organisms with an immediate source of glucose to support the cell's energy requirements. Epithelial cells primarily store energy as glycogen, but until recently it has not been reported as a major fuel source for cancer growth. Hypoxia, which occurs in many cancers, results in glycogen synthesis and increased survival under stressed conditions. Recently, glycogen mobilization has been shown to play a role in the maturation and immune activity of dendritic cells (DCs) and in the proliferation and metastatic efficiency of cancer cells aided by the tumor microenvironment (TME). These studies indicate that glycogen plays an important role in glucose homeostasis and contributes to key functions related to tumor aggressiveness and the survival of cancer cells.