Project description:Variability in gene expression is an important and largely unknown phenomenon responsible of tumor resistance to chemotherapy. Here, we show that energy metabolism proteins are highly variable, specially Glut1, G6PD, PKM2 and SDHA. In contrast, the variability of housekeeping proteins was low. We identified the PI3K/Akt/mTor pathway as the source of variability for PKM2.Variability was independent of the energy source used. However, cells grown on glucose down-regulate G6PDH and SDHA, promoting oxidative stress. Variability and chemotherapy plasticity were directly related, and the combination of drugs with opposite effect on the expression of plastic proteins resulted in positive synergy. Human solid tumor cells displayed higher variability in metabolic enzymes than cultured cells. The most aggressive tumors showed higher variability than less aggressive ones. This suggests that variability in energy metabolism enzymes could be a biomarker for tumor stratification and therapy election.
Project description:The detachment of epithelial cells, but not cancer cells, causes anoikis due to reduced energy production. Invasive tumor cells generate three splice variants of the metastasis gene osteopontin. The cancer-specific form osteopontin-c supports anchorage-independence through inducing oxidoreductases and upregulating intermediates/enzymes in the hexose monophosphate shunt, glutathione cycle, glycolysis, glycerol phosphate shuttle, and mitochondrial respiratory chain. Osteopontin-c signaling upregulates glutathione (consistent with the induction of the enzyme GPX-4), glutamine and glutamate (which can feed into the tricarboxylic acid cycle). Consecutively, the cellular ATP levels are elevated. The elevated creatine may be synthesized from serine via glycine and also supports the energy metabolism by increasing the formation of ATP. Metabolic probing with N-acetyl-L-cysteine, L-glutamate, or glycerol identified differentially regulated pathway components, with mitochondrial activity being redox dependent and the creatine pathway depending on glutamine. The effects are consistent with a stimulation of the energy metabolism that supports anti-anoikis. Our findings imply a synergism in cancer cells between osteopontin-a, which increases the cellular glucose levels, and osteopontin-c, which utilizes this glucose to generate energy. mRNA profiles of MCF-7 cells transfected with osteopontin-a, osteopontin-c and vector control were generated by RNA-Seq, in triplicate, by Illumina HiSeq.
Project description:The detachment of epithelial cells, but not cancer cells, causes anoikis due to reduced energy production. Invasive tumor cells generate three splice variants of the metastasis gene osteopontin. The cancer-specific form osteopontin-c supports anchorage-independence through inducing oxidoreductases and upregulating intermediates/enzymes in the hexose monophosphate shunt, glutathione cycle, glycolysis, glycerol phosphate shuttle, and mitochondrial respiratory chain. Osteopontin-c signaling upregulates glutathione (consistent with the induction of the enzyme GPX-4), glutamine and glutamate (which can feed into the tricarboxylic acid cycle). Consecutively, the cellular ATP levels are elevated. The elevated creatine may be synthesized from serine via glycine and also supports the energy metabolism by increasing the formation of ATP. Metabolic probing with N-acetyl-L-cysteine, L-glutamate, or glycerol identified differentially regulated pathway components, with mitochondrial activity being redox dependent and the creatine pathway depending on glutamine. The effects are consistent with a stimulation of the energy metabolism that supports anti-anoikis. Our findings imply a synergism in cancer cells between osteopontin-a, which increases the cellular glucose levels, and osteopontin-c, which utilizes this glucose to generate energy.
Project description:The NAT enzymes are polymorphic xenobiotic metabolizing enzymes that catalyze the transfer of an acetyl moiety from acetyl coenzyme A (acetyl-CoA) to the nitrogen or oxygen atom of primary arylamines, hydrazines, and their N-hydroxylated metabolites. NATs therefore play an important role in the detoxification and/or activation of arylamine drugs and carcinogens. The involvement of acetyl-CoA in energy metabolism suggests that there may be relationships between NAT activity and energy metabolism. Previous studies have suggested a role for NAT2 in insulin sensitivity that is exacerbated on high fat diet, using Nat1 knockout mice. To study mice with no NAT activity at all, we used a Nat1/Nat2 double-KO model, with animals fed either a regular chow or high fat/high sugar diet for 12 weeks. Analysis of basal parameters suggested a decrease in fatty-acid oxidation and hepatic gluconeogenesis. To further evaluate the cause of this, RNA was isolated and processed using Affymetrix Mouse Gene 2.0 microarrays.