Oxidative stress associates with aggressiveness in lung large-cell carcinoma
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Oxidative stress is involved in many cancer-related processes; however, current therapeutics are unable to benefit from this approach. The lungs have a very exquisite redox environment that may contribute to the frequent and deadly nature of lung cancer. Very few studies specifically address lung large-cell carcinoma (LCC), even though this is one of the major subtypes. Using bioinformatic (in silico) tools, we demonstrated that a more aggressive lung LCC cell line (HOP-92) has an overall increase activity of the human antioxidant gene (HAG) network (P = 0.0046) when compared to the less aggressive cell line H-460. Gene set enrichment analysis (GSEA) showed that the expression of metallothioneins (MT), glutathione peroxidase 1 (GPx-1), and catalase (CAT) are responsible for this difference in gene signature. This was validated in vitro, where HOP-92 showed a pro-oxidative imbalance, presenting higher antioxidant enzymes (superoxide dismutase (SOD), CAT, and GPx) activities, lower reduced sulfhydryl groups and antioxidant potential, and higher lipoperoxidation and reactive species production. Also, HAG network is upregulated in lung LCC patients with worst outcome. Finally, the prognostic value of genes enriched in the most aggressive cell line was assessed in this cohort. Isoforms of metallothioneins are associated with bad prognosis, while the thioredoxin-interacting protein (TXNIP) is associated with good prognosis. Thus, redox metabolism can be an important aspect in lung LCC aggressiveness and a possible therapeutic target.
KeywordsTumor progression Catalase Lung cancer Hydrogen peroxide H661
We thank Dr. Karin Purshouse for revising the manuscript and the Brazilians funds—PPSUS FAPERGS/MS/CNPq/SESRS/PPSUS (1121-2551/13-8), MCT/CNPq Universal (470306/2011-4), PRONEX/FAPERGS (1000274), PRONEM/FAPERGS (11/2032-5), PqG/FAPERGS (2414-2551/12-8), and MCT/CNPq INCT-TM (573671/2008-7)—for financial support.
Conflicts of interest
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