Studies on the molecular clock and the circadian regulation of hepatic tumor cell metabolism

MONJES NATALIA MARIBEL; GUIDO MARIO EDUARDO

Valparaíso

Congreso; XIV Latin American Symposium on Chronobiology 2017-LASC 2017; 2017

The circadian system comprising oscillators present in organs, tissues and even in individual cells temporally controls the body physiology. The clock liver regulates the metabolism under a circadian base mainly depending on feeding times; however, it is poorly understood how liver works under a malignant growth. The aim of this project was to investigate the molecular clock work and its linkage with the lipid metabolism in cultures of the human hepatoma cell line HepG2. We performed this study under two proliferative states, partial arrest and proliferation, maintaining cells with 0 or 5% of serum respectively after synchronization with dexamethasone (100 nM). We analyzed the expression of clock genes (CGs) (Bmal, Per, Cry), clock controlled genes (CCGs) (Rev-erb) and the main enzymes involved in the glycerophospholipid (GPL) biosynthesis (Chk, Pcyt2, Pemt) at the mRNA level by qPCR, and presence and distribution of BMAL1, PER1 and CHK proteins by immunocytochemistry. The mRNAs for most genes evaluated showed temporal oscillations under proliferation while no significant differences were observed in arrested cells except for Pcyt2. In addition, we studied the endogenous content of GPLs in proliferation and observed significant variations in the total and individual GPL level content at different times tested. These studies suggest that an active time-dependent control of gene expression and metabolism takes place in proliferating HepG2 cells. Supported by CONICET, ANPCyT-FONCYT, SECyT-UNC.