Post-translational modifications and the Warburg effect.

Post-translational modification (PTM) is an important step of signal transduction that transfers chemical groups such as phosphate, acetyl and glycosyl groups from one protein to another protein. As most of the PTMs are reversible, normal cells use PTMs as a 'switch' to determine the resting and proliferating state of cells that enables rapid and tight regulation of cell proliferation. In cancer cells, activation of oncogenes and/or inactivation of tumor suppressor genes provide continuous proliferative signals in part by adjusting the state of diverse PTMs of effector proteins that are involved in regulation of cell survival, cell cycle and proliferation, leading to abnormally fast proliferation of cancer cells. In addition to dysregulated proliferation, 'altered tumor metabolism' has recently been recognized as an emerging cancer hallmark. The most common metabolic phenotype of cancer is known as the Warburg effect or aerobic glycolysis that consists of increased glycolysis and enhanced lactate production even in the presence of oxygen. Although Otto Warburg observed aerobic glycolysis nearly 90 years ago, the detailed molecular mechanisms how increased glycolysis is regulated by oncogenic and/or tumor suppressive signaling pathways remain unclear. In this review, we summarize recent advances revealing how these signaling pathways reprogram metabolism through diverse PTMs to provide a metabolic advantage to cancer cells, thereby promoting tumor cell proliferation, tumorigenesis and tumor growth.