Targeting the mTOR Pathway in Tumor Malignancy

The mammalian target of rapamycin (mTOR) plays a critical role in the regulation of cell growth, proliferation, and metabolism by integrating growth factor stimulation and energy/nutrient input through a complex signaling network. The mTOR kinase is a part of two structurally and functionally distinct multiple protein complexes, mTORC1 and mTORC2. The mammalian target of rapamycin complex 1 (mTORC1) is rapamycin-sensitive and mediates temporal control of cell growth by regulating several cellular processes, such as translation, transcription, and nutrient transport while the mammalian target of rapamycin complex 2 (mTORC2) is insensitive to rapamycin and is involved in spatial control of cell growth via cytoskeleton regulation. Here we discuss the mechanism of mTOR regulation in tumor malignancy through a variety of signaling pathways and the potential of mTOR inhibitors for the treatment of cancer.