Temporal control of metabolism in proliferative glioblastoma cancer cells with differential time-regulated chemotherapy susceptibility

MARIO E. GUIDO; PAULA M. WAGNER; LUCAS G. SOSA-ALDERETE

Congreso; Neuroscience 2018; 2018

Circadian clocks driving transcriptional/translational rhythms in gene expression are even present in immortalized cell lines whereas metabolic rhythms conducted by an ancestral metabolic/redox clock can persist in enucleated cells or in the absence of transcription. Disruption of circadian rhythms by modern life (continuous illumination, shift work, jet lag, etc.) may cause metabolic disorders and higher cancer risk; however, little is known about clock functioning in tumor cells. Here we evaluated expression of clock and clock controlled genes, glycerophospholipid labelling, redox metabolisms (reactive oxygen species (ROS) levels and peroxiredoxin cycles) and cell susceptibility to bortezomib (BOR) chemotherapeutic treatment in cultures of glioblastoma T98G cells. For this, cells were kept under arrest (w/o serum) or proliferation (with serum), synchronized with dexamethasone (100 nM) (time 0) and collected at different times. In proliferative cells, mRNA expression for clock- (Bmal1, Per1, Rev-erbα) and glycerophospholipid synthesizing enzyme- genes did not display circadian rhythmicity or fluctuated with a shortened period (t=16 h) (data not shown) whereas the 32P-GPL labelling showed a 24 hrhythm (Fig. 1) and redox metabolism exhibited a 12 h- rhythmicity in ROS levels (Fig. 4) and longer peroxiredoxin oxidation cycles (t=30 h) (Fig. 2). Moreover, cell viabilitysignificantly changed over time after BOR (500 nM) chemotherapy (Fig. 5). Cell viability and redox state rhythms were altered when Bmal1 expression was knocked down by CRISPR/Cas 9 technology (Fig. 3) showing different amplitudes, phases or periods than wild type cells (Fig. 4b-5b). Nevertheless, observations indicate that an intrinsic metabolic clock continues to function in proliferating cells, controlling diverse metabolisms and highlighting differential states of tumor suitability for more efficient, time-dependent chemotherapy. Also, we may infer that cross-talk between oscillators takes place in tumor cells to ensure tumor growth and survival over time. Furthermore, regardless of the precise nature of the link between them, molecular and metabolic oscillators work in unison to maintain cellular homeostasis.