Abstract 2716: Lipid mediated “nutrients sensing” checkpoint in G1 phase of the cell cycle

Abstract

Abstract One of the hallmarks of cancers is dysregulation of G1 phase cell cycle progression- where cells decide their fate whether they should divide, arrest or undergo apoptosis. There is a growth factor-dependent Restriction point (R), where cells commit to replicate its genome or to enter a state of quiescence. Unicellular organisms only respond to the nutrients, a point known as START. In mammalian system, we have shown equivalent to START, “Cell Growth” checkpoints, where it senses Essential Amino Acids (EAAs), a “Conditionally” EAA glutamine (Q), and at last a checkpoint regulated by mTOR, which we think it senses nutrients and is the final arbitrator of the G1-S phase progression. mTOR- mammalian/mechanistic target of rapamycin integrates the growth factor signaling with nutrient sensing signaling and known to be involved in protein translation and proliferation. Another key nutrient needed for cell growth is lipids which is required as building blocks for plasma membrane synthesis and signaling molecules. Phosphatidic acid has been shown to be required for the activity of mTORC1 and mTORC2. In this study, we investigated the involvement of lipids in the cell cycle progression and how the signals are integrated. Upon lipid deprivation, normal fibroblasts cells arrest in G1-phase of the cell cycle. There is a distinct and distinguishable lipid sensing checkpoint from EAAs and Q. Temporally it is different from other nutrient sensing checkpoints in the late G1-phase of the cell cycle. In summary, there is a series of “nutrient sensing” checkpoints late in the G1-phase followed by mTOR “Growth” checkpoint. Dysregulation of these checkpoints in cancer cells may present better opportunity to target them with different therapeutic approach. Citation Format: Deven Patel, David Foster. Lipid mediated “nutrients sensing” checkpoint in G1 phase of the cell cycle. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2716.