Peroxiredoxin V Reduces β-Lapachone-induced Apoptosis of Colon Cancer Cells

The Role of Peroxiredoxins in Cancer Development

Peroxiredoxins (Prxs) are antioxidant enzymes with ubiquitous expression in human tissues. Prxs are expressed in archaea, bacteria, and eukaryota, often in multiple isoforms. Because of their abundant expression in different cellular organelles and extraordinary sensitivity to H2O2, Prxs are among the first defenses against oxidative stress. Prxs undergo reversible oxidation to disulfides, and some family members perform chaperone or phospholipase functions upon further oxidation. Prxs are upregulated in cancer cells. Research has suggested that Prxs can function as tumor promoters in various cancers. The major objective of this review is to summarize novel findings regarding the roles of Prxs in common cancer types. Prxs have been shown to influence differentiation of inflammatory cells and fibroblasts, remodeling of extracellular matrix, and regulation of stemness. Since aggressive cancer cells have higher intracellular levels of ROS that they can utilize to proliferate and metastasize compared to normal cells, it is critical that we understand the regulation and functions of primary antioxidants such as Prxs. These small but mighty proteins could prove to be key for improving cancer therapeutics and patient survival.

Effects of Antioxidant Gene Overexpression on Stress Resistance and Malignization In Vitro and In Vivo: A Review

Reactive oxygen species (ROS) are normal products of a number of biochemical reactions and are important signaling molecules. However, at the same time, they are toxic to cells and have to be strictly regulated by their antioxidant systems. The etiology and pathogenesis of many diseases are associated with increased ROS levels, and many external stress factors directly or indirectly cause oxidative stress in cells. Within this context, the overexpression of genes encoding the proteins in antioxidant systems seems to have become a viable approach to decrease the oxidative stress caused by pathological conditions and to increase cellular stress resistance. However, such manipulations unavoidably lead to side effects, the most dangerous of which is an increased probability of healthy tissue malignization or increased tumor aggression. The aims of the present review were to collect and systematize the results of studies devoted to the effects resulting from the overexpression of antioxidant system genes on stress resistance and carcinogenesis in vitro and in vivo. In most cases, the overexpression of these genes was shown to increase cell and organism resistances to factors that induce oxidative and genotoxic stress but to also have different effects on cancer initiation and promotion. The last fact greatly limits perspectives of such manipulations in practice. The overexpression of GPX3 and SOD3 encoding secreted proteins seems to be the "safest" among the genes that can increase cell resistance to oxidative stress. High efficiency and safety potential can also be found for SOD2 overexpression in combinations with GPX1 or CAT and for similar combinations that lead to no significant changes in H₂O₂ levels. Accumulation, systematization, and the integral analysis of data on antioxidant gene overexpression effects can help to develop approaches for practical uses in biomedical and agricultural areas. Additionally, a number of factors such as genetic and functional context, cell and tissue type, differences in the function of transcripts of one and the same gene, regulatory interactions, and additional functions should be taken into account.

Peroxiredoxin 5 protects HepG2 cells from ethyl β-carboline-3-carboxylate-induced cell death via ROS-dependent MAPK signalling pathways

Peroxiredoxin 5 (PRDX5) is the member of Prxs family, widely reported to be involved in various types of cell death. We previously found that PRDX5 knockdown increases the susceptibility of cell death upon oxidative stress treatment. Ethyl β-carboline-3-carboxylate (β-CCE), an alkaloid extracted from Picrasma quassioides, has been reported to play a role in neuronal disease, but its anti-cancer potential on liver cancers remains unknown. Here, we studied the effect of PRDX5 on ethyl β-carboline-3-carboxylate (β-CCE)-induced apoptosis of hepatomas. High expression level of PRDX5 was deeply related with the postoperative survival of patients with liver cancer, indicating that PRDX5 may be a biomarker of live cancer processing. Moreover, PRDX5 over-expression in HepG2 cells significantly inhibited β-CCE-induced cell apoptosis and cellular ROS levels as well as mitochondrial dysfunction. Signalling pathway analysis showed that β-CCE could significantly up-regulate the ROS-dependent MAPK signalling, which were in turn boosts the mitochondria-dependent cell apoptosis. Moreover, PRDX5 over-expression could reverse the anti-cancer effects induced by β-CCE in HepG2 cells. Our findings suggest that PRDX5 has a protective role on β-CCE-induced liver cancer cell death and provides new insights for using its anti-cancer properties for liver cancer treatment.

A CRISPR screen identifies redox vulnerabilities for KEAP1/NRF2 mutant non-small cell lung cancer

The redox regulator NRF2 is hyperactivated in a large percentage of non-small cell lung cancer (NSCLC) cases, which is associated with chemotherapy and radiation resistance. To identify redox vulnerabilities for KEAP1/NRF2 mutant NSCLC, we conducted a CRISPR-Cas9-based negative selection screen for antioxidant enzyme genes whose loss sensitized cells to sub-lethal concentrations of the superoxide (O2•-) -generating drug β-Lapachone. While our screen identified expected hits in the pentose phosphate pathway, the thioredoxin-dependent antioxidant system, and glutathione reductase, we also identified the mitochondrial superoxide dismutase 2 (SOD2) as one of the top hits. Surprisingly, β-Lapachone did not generate mitochondrial O2•- but rather SOD2 loss enhanced the efficacy of β-Lapachone due to loss of iron-sulfur protein function, loss of mitochondrial ATP maintenance and deficient NADPH production. Importantly, inhibition of mitochondrial electron transport activity sensitized cells to β-Lapachone, demonstrating that these effects may be translated to increase ROS sensitivity therapeutically.

Knockdown of Peroxiredoxin V increased the cytotoxicity of non-thermal plasma-treated culture medium to A549 cells

Administration of non-thermal plasma therapy via the use of plasma-activated medium (PAM) might be a novel strategy for cancer treatment, as it induces apoptosis by increasing reactive oxygen species (ROS) levels. Peroxiredoxin V (PRDX5) scavenges ROS and reactive nitrogen species and is known to regulate several physiological and pathological reactions. However, its role in lung cancer cells exposed to PAM is unknown. Here, we investigated the effect of PRDX5 in PAM-treated A549 lung cancer cells and determined the mechanism underlying its cytotoxicity. Cell culture medium was treated with low temperature plasma at 16.4 kV for 0, 60, 120, or 180 s to develop PAM. PRDX5 was knocked down in A549 cells via transfection with short hairpin RNA targeting PRDX5. Colony formation and wound healing assays, flow cytometry, fluorescence microscopy, and western blotting were performed to detect the effect of PRDX5 knockdown on PAM-treated A549 cells. PAM showed higher cytotoxicity in lung cancer cells than in control cells, downregulated the mitogen-activated protein kinase signaling pathway, and induced apoptosis. PRDX5 knockdown significantly inhibited cell colony formation and migration, increased ROS accumulation, and reduced mitochondrial membrane potential in lung cancer cells. Hence, PRDX5 knockdown combined with PAM treatment represents an effective option for lung cancer treatment.

Discovery of Antitumor Active Peptides Derived from Peroxiredoxin 5

The peroxiredoxin 5 (PRDX5) is a member of peroxiredoxins with antitumor activity. However, as a recombinant protein, PRDX5 is restricted in clinic due to high cost and keeping high dose in medication. The alternative way is to explore the antitumor active fragments of PRDX5 for potential of peptide drugs. According to the sequence, crystal structure and enzyme function of PRDX5, seven peptides were designed and named as IMB-P1∼7. The peptide IMB-P1 (AFTPGCSKTHLPGFVEQAEAL) containing critical residue C47 exhibited antitumor activity similar to PRDX5 in vivo. Transcriptome analysis showed peptide IMB-P1 could make influence on expression of multiple genes involved in tumorigenesis and deterioration. Besides, an important discovery is the down-regulation of oxidation-related genes. In CT26 cells, IMB-P1 carried similar antitumor activity with increasing ROS level to intact PRDX5. The results demonstrated that peptide IMB-P1 with easier synthesis from PRDX5 may serve as a promising antitumor candidate.

Assessment of Potential Prognostic Value of Peroxiredoxin 1 in Oral Squamous Cell Carcinoma

Purpose

The role of the peroxiredoxin (PRDX) family in oral squamous cell carcinoma (OSCC) remains unclear. This study aimed to investigate the expression of PRDXs and their effects on the prognosis in OSCC.

Methods

The expression of PRDXs and their effects on prognosis were analysed in 216 OSCC samples from The Cancer Genome Atlas (TCGA) database. OSCC tissues and adjacent noncancerous tissues (ANTs) were obtained from 68 clinical patients. Quantitative real-time (qRT)-PCR, Western blot, and immunohistochemical (IHC) staining were used to verify the relationship between the expression level of PRDX1 and different clinical features. Gene set enrichment analysis (GSEA) was used to examine the molecular mechanism of PRDX1 in OSCC.

Results

PRDX1 was found to be the only gene in PRDX family that highly expressed in OSCC samples and affected the prognosis of patients with OSCC. PRDX1 expression was significantly related to tumor stage, lymphatic metastasis, and pathological grade. A nomogram consisting of tumor stage, N stage, and PRDX1 level was constructed. GSEA showed that high expression of PRDX1 involved many cancer-related molecular functions and signaling pathways.

Conclusion

PRDX1 may play an important role in the occurrence and development of OSCC, and may be a potential new target for OSCC treatment.