IFI6 depletion inhibits esophageal squamous cell carcinoma progression through reactive oxygen species accumulation via mitochondrial dysfunction and endoplasmic reticulum stress

Abstract

Background: Esophageal squamous cell carcinoma (ESCC) is one of the most lethal forms of adult cancer with poor prognosis. Substantial evidence indicates that reactive oxygen species (ROS) are important modulators of aggressive cancer behavior. However, the mechanism by which ESCC cells integrate redox signals to modulate carcinoma progression remains elusive. Methods: The expression of interferon alpha inducible protein 6 (IFI6) in clinical ESCC tissues and cell lines was detected by RT-PCR and Western blotting. The correlation between IFI6 expression levels and aggressive ESCC disease stage was examined by immunohistochemistry. Bioinformatic analysis was conducted to explore the potential function of IFI6 in ESCC. ESCC cell lines stably depleted of IFI6 and ectopically expressing IFI6 were established using lentiviruses expressing shRNAs and an IFI6 expression plasmid, respectively. The effects of IFI6 on ESCC cells were determined by cell-based analyses, including EdU assay, apoptotic assay, cellular and mitochondria-specific ROS detection, seahorse extracellular flux, and mitochondrial calcium flux assays. Blue native-polyacrylamide gel electrophoresis was used to determine mitochondrial supercomplex assembly. Transcriptional activation of NADPH oxidase 4 (NOX4) via ATF3 was confirmed by dual luciferase assay. In vivo tumor growth was determined in mouse xenograft models. Results: We find that the expression of IFI6, an IFN-stimulated gene localized in the inner mitochondrial membrane, is markedly elevated in ESCC patients and a panel of ESCC cell lines. High IFI6 expression correlates with aggressive disease phenotype and poor prognosis in ESCC patients. IFI6 depletion suppresses proliferation and induces apoptosis by increasing ROS accumulation. Mechanistically, IFI6 ablation induces mitochondrial calcium overload by activating mitochondrial Ca 2+ uniporter and subsequently ROS production. Following IFI6 ablation, mitochondrial ROS accumulation is induced by mitochondrial supercomplex assembly suppression and oxidative phosphorylation dysfunction, while IFI6 overexpression produces the opposite effects. Furthermore, energy starvation induced by IFI6 inhibition drives endoplasmic reticulum stress, which upregulates NOX4-derived ROS production in an ATF3-dependent manner. Finally, the results in xenograft models of ESCC further corroborate the in vitro findings. Conclusion: Our study unveils a novel redox homeostasis signaling pathway that regulates ESCC pathobiology and identifies IFI6 as a potential druggable target in ESCC.

Procaspase-1 patrolled to the nucleus of proatherogenic lipid LPC-activated human aortic endothelial cells induces ROS promoter CYP1B1 and strong inflammation

“…RGN has been shown to have antioxidant properties by its activity reducing the production of reactive oxygen species and increasing the antioxidant defenses [ 115 ]. IFI6 depletion suppresses proliferation and induces apoptosis by increasing ROS accumulation, suggesting that IFI6 inhibits ROS accumulation [ 116 ]. Mitochondrial peptidase IMMP2L mutation causes early onset of age-associated disorders and impairs adult stem cell self-renewal [ 117 ], suggesting that IMMP2L inhibits ROS generation.…”

Mimicking tumor cell heterogeneity of colorectal cancer in a patient-derived organoid-fibroblast model

“…5B and table S9). In two of the three patients we identified a cluster of genes upregulated in both co-culture conditions including MUC5AC , IFI6 and 27, SerpinA1 and LYPD8 , which were previously reported to be involved in tumor progression and metastasis, tumor cell proliferation and poor patient prognosis ( 47–49 ). In the ENAS condition we found upregulation of NMU, EREG and SNHG12 genes.…”

IFI6 Downregulation Reverses Oxaliplatin Resistance of Colorectal Cancer Cells by Activating the ROS-Induced p38MAPK Signaling Pathway

“…Downregulation of IFI6 could inhibit ESCC progression through ROS accumulation. 21) To determine whether IFI6 activated p38MAPK signaling pathway was elicited by ROS, we measured the ROS level in HCT116/OXA cells (treated with 4 µM OXA) and found that IFI6 knockdown displayed an enhanced ROS level in cells (Figs. 6A, B).…”

“…20) In fact, IFI6 is considered as a factor that can promote proliferation and anti-apoptosis in previous reported studies. 19,21,22) Importantly, both in vitro and in vivo results have displayed that chemotherapeutic drugs often activate the apoptosis pathway, thereby promoting their cytotoxicity and inhibiting tumor growth. 23) Therefore, we wondered that if IFI6 was involved in regulating chemoresistance of CRC cells.…”