Inhibition of Glutaredoxin 5 predisposes Cisplatin-resistant Head and Neck Cancer Cells to Ferroptosis

Abstract

Rationale: Loss of iron-sulfur cluster function predisposes cancer cells to ferroptosis by upregulating iron-starvation response, but the role of glutaredoxin 5 (GLRX5) silencing in ferroptosis remains unknown. We examined the role of GLRX5 functional loss in promoting ferroptosis in cisplatin-resistant head and neck cancer (HNC) cells. Methods: The effects of sulfasalazine treatment and GLRX5 gene silencing were tested on HNC cell lines and mouse tumor xenograft models. These effects were analyzed concerning cell viability and death, lipid reactive oxygen species (ROS) and mitochondrial iron production, labile iron pool, mRNA/protein expression, and malondialdehyde assays. Results: Cyst(e)ine deprivation, erastin, or sulfasalazine induced ferroptosis in HNC cells, which was relatively less sensitive in cisplatin-resistant HNC cells. Sulfasalazine or cyst(e)ine deprivation-induced ferroptosis resulted from increased lipid peroxidation and intracellular free iron, which were significantly promoted by short-interfering RNA or short hairpin RNA (shRNA) targeting GLRX5 ( P <0.05). GLRX5 silencing activated iron-starvation response and boosted up intracellular free iron through the iron-responsive element-binding activity of increased iron regulatory protein (increased transferrin receptor and decreased ferritin). These effects were rescued by resistant GLRX5 cDNA but not by catalytically inactive mutant GLRX5 K101Q. The same results were noted in an in vivo mouse model transplanted with vector or shGLRX5-transduced HNC cells and treated with sulfasalazine. Conclusion: Our data suggest that inhibition of GLRX5 predisposes therapy-resistant HNC cells to ferroptosis.

Systematic Surveys of Iron Homeostasis Mechanisms reveal Ferritin Superfamily and Nucleotide Surveillance Regulation to be Modified by PINK1 Absence

“…In human non-hematopoietic cells with GLRX5 deficiency, the reported consequences include a deficit of mitochondrial ISC biogenesis, increased IRP1-mediated repression of ferritin mRNA translation, and elevated TFR1-mediated iron import with subsequent accumulation of cytosolic/mitochondrial iron [63]. It was also observed that cells with GLRX5 deficiency show abnormally high LIP, repressed ferritin levels, and an augmented vulnerability to ferroptosis [169], as appears to be the case also for Pink1 -/-cells. Notions that the mitochondrial dysfunction inherent in PD leads to progressively conspicuous efforts to maximize ISC-biogenesis are also supported by a report that the abundance of the ISC export factor ABCB7 increased abnormally over time in the neurotoxic MPTP mouse model of PD [170].…”

Celastrol induces ROS-mediated apoptosis via directly targeting peroxiredoxin-2 in gastric cancer cells

“…Targeting biochemical alterations uniquely exhibited by cancer cells may provide therapeutic activity and selectivity in treating cancers 1 . Reactive oxygen species (ROS) are normal by-products of cellular processes, such as mitochondrial metabolism and protein folding.…”

Novel insights into ferroptosis: Implications for age-related diseases

“…When the intracellular lipid ROS level exceeds the antioxidant activity of GPX4, it leads to the disruption of redox homeostasis 10 . Ferrous iron can trigger harmful peroxidation of PUFAs in membrane phospholipids by forming toxic lipid radicals, eventually leading to cell death 11 . Iron accumulating within several organs during aging, such as brain and muscle, leads to increased oxidative damage and functional decline.…”