The T98G glioblastoma as a model to investigate the circadian clock function in human tumor cells

SOSA ALDERETE LG; ACOSTA-RODRÍGUEZ VA; GUIDO ME

Mendoza

Congreso; XLVIII Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB); 2012

Circadian clocks present in the brain, peripheral tissues and even in immortalized cell lines, temporally regulate a number of cellular and metabolic processes. The disruption of biological clocks may lead to diverse pathologies; however, little is known about the activity of circadian clocks in tumor cells. To this aim, we use the T98G cells derived from a human glioblastoma to investigate potential rhythmic responses under non-proliferative conditions. We looked first for a protocol to obtain quiescent cells able to be synchronized by extracellular signals: horse serum (HS, 2 h) or dexamethasone (100 nM DEX, 20 min). For this, cells were grown for 48 h in 10% FBS-DMEM to reach confluence and then, they were treated with HS or DEX. After synchronization, cells were maintained in serum free DMEM for 24 h, collected at different times from 0 to 32 h and subjected to flow cytometry or RT-PCR for further analysis. The cytometry clearly shows that only cells synchronized by DEX were mostly arrested: 57-79% of cells were at G0-G1 phases at the different times examined while less than 12% of cells were mitotic. Preliminary results indicate that synchronized cells expressed the clock gene Bmal1 mRNA with higher levels during the first 4-8 h. Our results suggest that T98G cells synchronized by DEX are mostly quiescent and display circadian rhythmicity in the expression of Bmal1.