Nutritional Stress in Head and Neck Cancer Originating Cell Lines: The Sensitivity of the NRF2-NQO1 Axis

Abstract

Nutritional stress disturbs the cellular redox-status, which is characterized by the increased generation of reactive oxygen species (ROS). The NRF2-NQO1 axis represents a protective mechanism against ROS. Its strength is cell type-specific. FaDu, Cal 27 and Detroit 562 cells differ with respect to basal NQO1 activity. These cells were grown for 48 hours in nutritional conditions (NC): (a) Low glucose–NC2, (b) no glucose, no glutamine–NC3, (c) no glucose with glutamine–NC4. After determining the viability, proliferation and ROS generation, NC2 and NC3 were chosen for further exploration. These conditions were also applied to IMR-90 fibroblasts. The transcripts/transcript variants of NRF2 and NQO1 were quantified and transcript variants were characterized. The proteins (NRF2, NQO1 and TP53) were analyzed by a western blot in both cellular fractions. Under NC2, the NRF2-NQO1 axis did not appear activated in the cancer cell lines. Under NC3, the NRF2-NQO1axis appeared slightly activated in Detroit 562. There are opposite trends with respect to TP53 nuclear signal when comparing Cal 27 and Detroit 562 to FaDu, under NC2 and NC3. The strong activation of the NRF2-NQO1 axis in IMR-90 resulted in an increased expression of catalytically deficient NQO1, due to NQO1*2/*2 polymorphism (rs1800566). The presented results call for a comprehensive exploration of the stress response in complex biological systems.

The diverse functionality of NQO1 and its roles in redox control

“…Whether conformational changes in NQO1 result in altered location of the protein is intriguing and needs to be further investigated. NQO1 is known to be primarily cytosolic but has been reported to have significant nuclear, mitochondrial and membrane pools in different cell types [ 3 , 9 , [217] , [218] , [219] ].…”

Cell-Type Specific Metabolic Response of Cancer Cells to Curcumin

“…The efficacy of reverse transcription was assessed with the end-point polymerase chain reaction (PCR) using the primer pair GAPDH 1/GAPDH 2. For discovering the potentially present traces of contaminating DNA, the primer pair GAPDH2/GAPDH3 was used, as the sequence of the GAPDH3 primer is complementary to the nucleotides in intron 5 [37]. One microliter of diluted cDNA was used as a standard volume in all end-point PCR reactions.…”

Roles and Functions of ROS and RNS in Cellular Physiology and Pathology

“…In particular, they studied the NRF2-NQO1 axis, which represents a protective mechanism against oxidative stress. Their study involved different cancer cell lines (FaDu, Cal 27, and Detroit 562), which have different basal NQO1 activity and were exposed to the absence of glucose and glutamine, or solely to the low levels of either glucose or glutamine [5]. While all the cells lines analyzed showed sensitivity to glucose deprivation, their differential activation of the NRF2-NQO1 axis resulted in a differently increased expression of NQO1.…”