The key role of structural cells in immune modulation has been revealed with the advent of single-cell multiomics, but the underlying mechanism remains poorly understood. Here, we revealed that the transcriptional activation of interferon regulatory factor 1 (IRF1) in response to ionizing radiation, cytotoxic chemicals and SARS-CoV-2 viral infection determines the fate of structural cells and regulates communication between structural and immune cells. Radiation-induced leakage of mtDNA initiates the nuclear translocation of IRF1, enabling it to regulate the transcription of inflammation- and cell death-related genes. Novel posttranslational modification (PTM) sites in the nuclear localization sequence (NLS) of IRF1 were identified. Functional analysis revealed that mutation of the acetylation site and the phosphorylation sites in the NLS blocked the transcriptional activation of IRF1 and reduced cell death in response to ionizing radiation. Mechanistically, reciprocal regulation between the single-stranded DNA sensors SSBP1 and IRF1, which restrains radiation-induced and STING/p300-mediated PTMs of IRF1, was revealed. In addition, genetic deletion or pharmacological inhibition of IRF1 tempered radiation-induced inflammatory cell death, and radiation mitigators also suppressed SARS-CoV-2 NSP-10-mediated activation of IRF1. Thus, we revealed a novel cytoplasm-oriented mechanism of IRF1 activation in structural cells that promotes inflammation and highlighted the potential effectiveness of IRF1 inhibitors against immune disorders.

Abstract Genotoxic therapy triggers reactive oxygen species (ROS) production and oxidative tissue injury. S-nitrosylation is a selective and reversible posttranslational modification of protein thiols by nitric oxide (NO), and 5,6,7,8-tetrahydrobiopterin (BH4) is an essential cofactor for NO synthesis. However, the mechanism by which BH4 affects protein S-nitrosylation and ROS generation has not been determined. Here, we showed that ionizing radiation disrupted the structural integrity of BH4 and downregulated GTP cyclohydrolase I (GCH1), which is the rate-limiting enzyme in BH4 biosynthesis, resulting in deficiency in overall protein S-nitrosylation. GCH1-mediated BH4 synthesis significantly reduced radiation-induced ROS production and fueled the global protein S-nitrosylation that was disrupted by radiation. Likewise, GCH1 overexpression or the administration of exogenous BH4 protected against radiation-induced oxidative injury in vitro and in vivo. Conditional pulmonary Gch1 knockout in mice (Gch1 fl/fl ; Sftpa1-Cre +/− mice) aggravated lung injury following irradiation, whereas Gch1 knock-in mice (Gch1 lsl/lsl ; Sftpa1-Cre +/− mice) exhibited attenuated radiation-induced pulmonary toxicity. Mechanistically, lactate dehydrogenase (LDHA) mediated ROS generation downstream of the BH4/NO axis, as determined by iodoacetyl tandem mass tag (iodoTMT)-based protein quantification. Notably, S-nitrosylation of LDHA at Cys163 and Cys293 was regulated by BH4 availability and could restrict ROS generation. The loss of S-nitrosylation in LDHA after irradiation increased radiosensitivity. Overall, the results of the present study showed that GCH1-mediated BH4 biosynthesis played a key role in the ROS cascade and radiosensitivity through LDHA S-nitrosylation, identifying novel therapeutic strategies for the treatment of radiation-induced lung injury.

The biological mechanisms triggered by low-dose exposure still need to be explored in depth. In this study, the potential mechanisms of low-dose radiation when irradiating the BEAS-2B cell lines with a Cs-137 gamma-ray source were investigated through simulations and experiments. Monolayer cell population models were constructed for simulating and analyzing distributions of nucleus-specific energy within cell populations combined with the Monte Carlo method and microdosimetric analysis. Furthermore, the 10 × Genomics single-cell sequencing technology was employed to capture the heterogeneity of individual cell responses to low-dose radiation in the same irradiated sample. The numerical uncertainties can be found both in the specific energy distribution in microdosimetry and in differential gene expressions in radiation cytogenetics. Subsequently, the distribution of nucleus-specific energy was compared with the distribution of differential gene expressions to guide the selection of differential genes bioinformatics analysis. Dose inhomogeneity is pronounced at low doses, where an increase in dose corresponds to a decrease in the dispersion of cellular-specific energy distribution. Multiple screening of differential genes by microdosimetric features and statistical analysis indicate a number of potential pathways induced by low-dose exposure. It also provides a novel perspective on the selection of sensitive biomarkers that respond to low-dose radiation.

BACKGROUND:Radiation-induced skin injury (RISI) represents a significant complication in patients receiving radiotherapy and individuals exposed to nuclear accidents, characterized by a protracted wound-healing process relative to injuries from other etiologies. Current preventive and management approaches remain inadequate. Consequently, investigating efficacious intervention strategies that target the disease's progression characteristics holds significant practical importance. METHODS:Small interfering RNA (siRNA) and overexpression plasmid were used to modulate the expression of Marvel domain containing 3 (Marveld3) and paired related homeobox 2 (PRRX2). Protein and mRNA levels were estimated by Western Blot and real-time PCR, respectively. Intracellular levels of Malondialdehyde (MDA), a terminal product of lipid peroxidation, were measured following the manufacturer's protocol for MDA assay kit. Similarly, intracellular levels of ferrous iron (Fe2+) and reactive oxygen species (ROS) were determined using their respective assay kits. Lipid peroxidation status within the cells was evaluated via BODIPY staining. Immunohistochemistry was conducted to ascertain the expression of PRRX2 in skin tissues collected at various time points following irradiation of rats. The H-score method was used to evaluate the percentage of positively stained cells and staining intensity. RNA sequencing, Gene Ontology (GO) analysis, and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis were conducted by OE Biotech Company. RESULTS:In this study, our findings indicated that Marveld3 suppression could effectively inhibit lipid peroxidation levels in irradiated skin cells, concomitantly reducing intracellular Fe2+ content. Additionally, the silencing of Marveld3 effectively abrogated the impact of a ferroptosis agonist on cellular viability, resulting in the upregulation of 66 and 178 genes, as well as the downregulation of 188 and 31 genes in irradiated HaCaT and WS1 cells, respectively. Among the differentially expressed genes, the PRRX2 which was found to be involved in the process of ferroptosis, exhibited statistically significant upregulation. And the upregulation of PRRX2 expression may attenuate radiation-induced lipid peroxidation in skin cells, thereby functioning as a potential stress-responsive mechanism to counteract radiation effects. CONCLUSIONS:This study elucidates the role of Marveld3 in radiation-induced ferroptosis in skin cells. Inhibition of Marveld3 led to the upregulation of PRRX2, which subsequently resulted in a reduction of Fe2+ and ROS levels, as well as the suppression of lipid peroxidation. These effects collectively mitigated the occurrence of ferroptosis.

Objective:To investigate the effects and mechanisms of copper transporter 1 (CTR1) in radiation induced intestinal injury in vitro. Methods:Human small intestinal epithelial cells (HIEC) were irradiated with 2, 4, 6, 8 Gy of X-rays and rat intestinal epithelial cells (IEC-6) were irradiated with 5, 10, 15, 20 Gy of X-rays. At 2, 4, 8, 24, and 48 h after irradiation, the expression of CTR1 was detected by Western blot assay. In some experiments, HIEC and IEC-6 cells were transfected with CTR1 shRNA and then exposed to X-rays. Copper levels were detected by Inductively Coupled Plasma Mass Spectrometry (ICP-MS). The radiosensitivity of cells was verified by colonogenic assay, the cellular reactive oxygen species (ROS) level and DNA damage were detected to further explore the related mechanism. In addition, Western blot was applied to detect the expressions of antioxidants and cuproptosis associated proteins in enterocytes after silencing CTR1 or irradiation.Results:The expression of CTR1 was increased by X-ray irradiation in a dose-dependent manner ( t=3.53, 3.45, 6.37, 11.11, 11.13, P<0.05). CTR1 expression was successfully diminished by CTR1 shRNA adenovirus vectors. According to the survival curves, the enhancement ratios of the radiosensitivity of HIEC and IEC-6 cells with CTR1 knocking-down were 1.146 and 1.201, respectively. Radiation-induced copper accumulation was alleviated after CTR1 silencing in IEC-6 cells ( t=3.10, P<0.05). At 0.5 h after irradiation, the ROS production in the CTR1 knockdown group was significantly lower than that in the control group ( t=5.23, 2.96, P<0.05). At 1 h after irradiation, the protein expression of γ-H2AX in the CTR1 knockdown group was obviously lower than that in the control group ( t=7.50, 4.29, P<0.05). The expressions of Nrf2 and HO-1 were increased after irradiation, which could be further increased after CTR1 silencing. In addition, cuproptosis associated protein DLAT, LIAS and FDX1 were reduced post-irradiation, which were recovered after CTR1 silencing. Conclusions:The radioresistance of HIEC and IEC-6 cells was enhanced after CTR1 silencing, possibly through the intracellular ROS and cuproptosis pathway.

OBJECTIVE:Radiogenic skin injury (RSI) is a common complication during cancer radiotherapy or accidental exposure to radiation. The aim of this study is to investigate the metabolism of bile acids (BAs) and their derivatives during RSI. METHODS:Rat skin tissues were irradiated by an X-ray linear accelerator. The quantification of BAs and their derivatives were performed by liquid chromatography-mass spectrometry (LC-MS)-based quantitative analysis. Key enzymes in BA biosynthesis were analyzed from single-cell RNA sequencing (scRNA-Seq) data of RSI in the human patient and animal models. The in vivo radioprotective effect of deoxycholic acid (DCA) was detected in irradiated SD rats. RESULTS:Twelve BA metabolites showed significant differences during the progression of RSI. Among them, the levels of cholic acid (CA), DCA, muricholic acid (MCA), chenodeoxycholic acid (CDCA), glycocholic acid (GCA), glycohyodeoxycholic acid (GHCA), 12-ketolithocholic acid (12-ketoLCA) and ursodeoxycholic acid (UDCA) were significantly elevated in irradiated skin, whereas lithocholic acid (LCA), tauro-β-muricholic acid (Tβ-MCA) and taurocholic acid (TCA) were significantly decreased. Additionally, the results of scRNA-Seq indicated that genes involved in 7a-hydroxylation process, the first step in BA synthesis, showed pronounced alterations in skin fibroblasts or keratinocytes. The alternative pathway of BA synthesis is more actively altered than the classical pathway after ionizing radiation. In the model of rat radiogenic skin damage, DCA promoted wound healing and attenuated epidermal hyperplasia. CONCLUSIONS:Ionizing radiation modulates the metabolism of BAs. DCA is a prospective therapeutic agent for the treatment of RSI.

Purpose Keloids are benign dermal tumors that arise from abnormal wound healing processes following skin lesions. Surgical excision followed by radiotherapy plays an important role in the treatment of keloids. Nevertheless, radioresistance remains a serious impediment to treatment efficacy. Investigation of the molecular response of keloids to radiation may contribute to radiosensitizing strategies. Materials and methods Primary keloid fibroblasts from human keloids were isolated and irradiated with X-ray. The expression profiles of messenger RNA (mRNA) in nonradiated and irradiated primary keloid fibroblasts were measured by mRNA sequencing analysis. Then, we identified common motifs and corresponding transcription factors of dysregulated mRNAs by using bioinformatic analysis of the proximal promoters. Whereafter, GO and KEGG were used to analyze the functional enrichment of the differentially expressed genes. Results We found that radiation not only suppressed proliferation but also increased cell senescence of primary keloid fibroblasts. There were 184 mRNAs and 204 mRNAs that showed significant changes in 4 and 8 Gy irradiated primary keloid fibroblasts, respectively. Among them, 8 upregulated and 30 downregulated mRNAs showed consistent alterations in 4 and 8 Gy irradiated primary keloid fibroblasts. More importantly, the xForkhead box O1 (FOXO1) signaling pathway was involved in the irradiation response. Pretreatment with the FOXO1 signaling inhibitor AS1842856 significantly promoted LDH release, apoptosis and senescence of primary keloid fibroblasts following irradiation. Conclusion Our findings illustrated the molecular changes in human keloid fibroblasts in response to radiation, and FOXO1 pathway inhibition is expected to provide a novel strategy for the radiosensitization of keloids.

BackgroundHepatocellular carcinoma (HCC) is the most common type of liver cancer. Recently, developments in radiotherapy technology have led to radiotherapy becoming one of the main therapeutics of HCC. Therefore, a suitable animal model for radiotherapy of the orthotopic HCC mouse model is urgently needed. MethodsIn the present study, Hepa1-6 cells were injected into the liver of C57BL/6 mice in situ to mimic the pathological characteristics of the original HCC. Tumor formation was monitored by applying magnetic resonance imaging techniques and verified by H & E histopathological staining, AFP staining, and Ki67 staining. A single dose of 10 Gy X-ray was applied to simulate clinical radiotherapy plans using image-guided radiotherapy (IGRT) equipment. The efficiency of radiotherapy was then assessed by examining tumor size and weight one week after radiation. Cleaved-caspase3 staining and TUNEL were used to assess apoptosis in tumor tissues. ResultsIntrahepatic tumor development was detected in the liver according using MRI. A high-density shadow could be seen 10 days after cell injection, which indicated the formation of HCC in vivo. The tumors grew steadily bigger, and underwent precision radiotherapy 20 days after injection. The typical pathological characteristics of HCC, such as large, deeply stained nuclei and irregular cell size, were visible with H & E staining. After radiotherapy, significantly higher expression of the immunohistochemical markers Ki67 and AFP were detected in tumor tissue than in the nearby normal tissue. Compared with the control group, the tumor volume (p = 0.05) and weight (p < 0.05) of the irradiated group were significantly reduced. In addition, a higher frequency of apoptosis was identified in irradiated HCC tumor tissue using the TUNEL and cleaved-caspase3 staining assay. ConclusionsIn a well-established orthotopic HCC model, MRI was utilized to monitor the formation of tumors, and IGRT was used to simulate clinical radiotherapy. The present study could provide a suitable preclinical system for HCC radiotherapy-related studies.

Radon is a naturally occurring radioactive gas and considered as a serious carcinogen to humans. Continuous radioactive decay of this gas emits high-energy alpha particles. Long-term radon exposure induces oxidative stress and inflammatory response, which results in chronic lung diseases. However, biological effects after radon exposure in other organs have been rarely reported. As the outermost organ of the human body, the skin suffers from environmental damage to agents such as air pollution. Epidemiological studies indicated that areas with high level of radon had a high incidence of skin cancer. However, whether radon exposure induces skin damage has not been reported yet. In this study, we established a radon-exposed mouse model and found that radon exposure affected the structure of skin tissues, which was manifested by inflammatory cell infiltration and skin atrophy. Using proteomic approach, we found 45 preferentially expressed proteins in 60 Working Level Months (WLM) group and 314 preferentially expressed proteins in 120 WLM group from radon-exposed skin tissues. Through microRNA (miRNA) sequencing profiling analysis, 57 dysregulated miRNAs were screened between the control and radon-treated mouse skin. By integrating the dysregulated proteins and miRNAs, radon-induced fatty acid synthase (FASN) was investigated in greater detail. Results showed that FASN was regulated by miR-206-3p and miR-378a-3p and involved in the pathogenesis of radon-induced skin damage. Overexpression of FASN inhibited the proliferation, and induced in WS1 cells. Our present findings illustrate the molecular change during radon-induced skin damage and the potential role of FASN during this process.

ObjectiveTo investigate the protective effect of bexarotene in radiation-induced skin injury and elucidate underlying mechanism.MethodsIrradiated cellular and animal models were established using an X-ray linear accelerator. Cell viability and apoptosis were evaluated by CCK8 and flow cytometry. In vivo protective effect of bexarotene was measured in irradiated SD rats. The antioxidant capacity of bexarotene was validated by DCF-DA method. The signaling pathways involved in bexarotene-mediated skin repair were enriched by RNA sequencing.ResultsBexarotene could significantly restore the proliferation and inhibit the apoptosis of WS1 cells with radiation damage (P ​< ​0.05). Moreover, bexarotene could effectively shorten the process of skin damage and promote skin repair in a rat model of radiation-induced skin injury (P ​< ​0.05). Mechanistically, bexarotene effectively reduced the expression of RXRα (P ​< ​0.05), thus leading to an early decrease in reactive oxygen species (ROS) after radiation exposure. Furthermore, a transcriptome analysis indicated that bexarotene-mediated recovery of radiation damage involves redox signaling, immune regulation, lipid metabolism and autophagy.ConclusionBexarotene is a promising therapeutic agent in the treatment of radiation-induced skin injury.

Background: Radiation-induced skin injury is a serious concern during radiotherapy and accidental ex-posure to radiation. Objective: This study aims to investigate the molecular events in early response to ionizing radiation of skin tissues and underlying mechanism.Methods: Mice and rats were irradiated with an electron beam. Skin tissues were used for liquid chro-matography-mass spectrometry (LC-MS)-based metabolomics, mRNA-Seq and single-cell RNA sequencing (scRNA-Seq). Human keratinocytes (HaCaT) and skin fibroblasts (WS1) were used for functional studies. Results: The integrated analysis of metabolomics and transcriptomics showed that 6 key fatty acid -asso-ciated metabolites, 9 key fatty acid-associated genes and multiple fatty acid-associated pathways were most obviously enriched and increased in the irradiated skins. Among them, acyl-CoA dehydrogenase very long chain (ACADVL) was investigated in greater detail due to its most obvious expression difference and sig-nificance in fatty acid metabolism. ScRNA-Seq of rat skin from irradiated individuals revealed that ACADVL was expressed in all subpopulations of skin tissues, with variations at different timepoints after radiation. Immunohistochemistry confirmed an increased ACADVL expression in the epidermis from human sample and various animal models, including monkeys, rats and mice. The knockdown of ACADVL increased the radiosensitivity of human keratinocytes and human skin fibroblasts. Silencing of ACADVL facilitated the expression of apoptosis and pyroptosis-related proteins following ionizing radiation.Conclusion: This study illustrated that cutaneous fatty acid metabolism was altered in the early response of ionizing radiation, and fatty acid metabolism-associated ACADVL is involved in radiation-induced cell death.(c) 2023 Japanese Society for Investigative Dermatology. Published by Elsevier B.V. All rights reserved.

Radiation-induced skin fibrosis is a late effect of radiation-induced skin injury. It is a common complication of tumor radiotherapy and radioactive nuclear accidents, which seriously affects the life quality of patients. Radiation-induced skin fibrosis is characterized by changes in skin appearance, loss of skin elasticity and contracture, hard skin and difficult to pinch creases, which may be accompanied by capillary dilatation, pain and itching. Some patients may even develop progressive fibrosis and recurrent skin infections. However, the mechanism of radiation-induced skin fibrosis is not completely clear at present, and there are no effective drugs and therapies to prevent or mitigate this disease. Therefore, it is particularly important to explore the mechanism of ionizing radiation-induced skin fibrosis and find more effective prevention and treatment methods. This article reviews the influencing factors, clinical manifestations, mechanism and treatment of radiation-induced skin fibrosis, and prospects its development, aiming to provide a reference for the research of radiation-induced skin fibrosis.

Radiation-induced skin injury (RISI) commonly occur in cancer patients who received radiotherapy and is one of the first clinical symptoms after suffering from nuclear exposure. Oxidative damage is the major causes of RISI. Nuclear factor erythroid 2-related factor 2 (Nrf2) is considered as a key mediator of the cellular antioxidant response. However, whether Nrf2 can alleviate RISI after high-dose irradiation remains unknown. In this study, we demonstrated that Nrf2-deficient (Nrf2(-/-)) mice were susceptible to high-dose irradiation and adenovirus-mediated overexpression of Nrf2 (ad-Nrf2) protected against radiation in skin cells. Overexpression of Nrf2 attenuated the severity of skin injury after high-dose electron beam irradiation. To uncover the mechanisms of Nrf2 involved in RISI, mRNA sequencing technology was performed to analyze the mRNA expression profiles of Ad-Nrf2 skin cells following radiation. The results revealed that a total of 127 genes were significantly changed, 55 genes were upregulated, and 72 genes were downregulated after Nrf2 overexpression. GSEA showed that Nrf2 was associated with positive regulation of genes involved in the reactive oxygen species pathway after radiation. Taken together, this study illustrated the role of Nrf2 in RISI and provided potentially strategies for ameliorating RISI.

Severe radiation-induced skin injury is a complication of tumor radiotherapy and nuclear accidents. Cell therapy is a potential treatment for radiation-induced skin injury. The stromal vascular fraction (SVF) is a newer material in stem cell therapy that is made up of stem cells harvested from adipose tissue, which has been shown to promote the healing of refractory wounds of different causes. In this study, SVF was isolated from patients with radiation-induced skin injury. Adipose-derived stem cells (ADSCs) accounted for approximately 10% of the SVF by flow cytometry. Compared with the control group of rats, administration with SVF attenuated the skin injury induced by electron beam radiation. The effect of SVF on the human skin fibroblast microenvironment was determined by proteomic profiling of secreted proteins in SVF-co-cultured human skin fibroblast WS1 cells. Results revealed 293 upregulated and 1,481 downregulated proteins in the supernatant of SVF-co-cultured WS1 cells. WS1 co-culture with SVF induced secretion of multiple proteins including collagen and MMP-1. In the clinic, five patients with radiation-induced skin injury were recruited to receive SVF transfer-based therapy, either alone or combined with flap transplantation. Autogenous SVF was isolated and introduced into a multi-needle precision electronic injection device, which automatically and aseptically distributed the SVF to the exact layer of the wound in an accurate amount. After SVF transfer, wound healing clearly improved and pain was significantly relieved. The patients' skin showed satisfactory texture and shape with no further wound recurrence. Our findings suggest that transplantation of SVF could be an effective countermeasure against severe radiation-induced skin injury.

Background: Radiation-induced skin injury is a serious concern during radiotherapyand radiation accidents. Skin fat represents the dominant architectural component of the human skin. However, the interplay between skin fat and the progression of radiation-induced skin injury remains largely unexplored. Objective: This study aims to elucidate the interplay between skin fat and the progression of radiation-induced skin injury. Methods: SD rats were irradiated with an electron beam. mRNA profiles were determined by RNA-Seq. The skin lipid mass was monitored by magnetic resonance imaging (MRI) and lipid profiles were measured by liquid chromatography-mass spectrometry (LC-MS). Human mature adipocytes isolated from dermal and subcutaneous white adipose tissues (WATs) were co-cultured with human keratinocytes (HaCaT) and skin fibroblasts (WS1) in the transwell culture system. Cell migration ability was measured by migration assay. Results: Radiation modulated cutaneous lipid metabolism by downregulating multiple pathways. Moreover, radiation decreased skin fat mass with altered lipid metabolite profiles. The rats fed with a high-fat diet showed resistance to radiogenic skin injury compared with that with a control diet, indicating that skin lipid plays a radioprotective role. Mature adipocytes promoted the migration but not the proliferation of co-cultured skin keratinocytes and fibroblasts. Palmitic acid, the most abundant fatty acid in skin tissues, facilitated the migration ofWS1 cells. Moreover, fatty acid-binding protein 4 (FABP4)could be incorporated into skin cells and promote DNA damage repair in irradiated skin fibroblasts. Conclusion: Radiation induces cutaneous lipid remolding, and skin adipocytes confer a protective role against radiation-induced skin injury. (C) 2020 Japanese Society for Investigative Dermatology. Published by Elsevier B.V. All rights reserved.

BACKGROUND:Radiation-induced skin injury is one of the main adverse effects and a dose-limiting factor of radiotherapy without feasible treatment. The underlying mechanism of this disease is still limited.OBJECTIVE:To investigate the potential molecular pathways and mechanisms of radiation-induced skin injury.METHODS:mRNA expression profiles were determined by Affymetrix Human HTA2.0 microarray.IFI6 overexpression and knockdown were mediated by lentivirus. The functional changes of skin cells were measured by flow cytometry, ROS probe and Edu probe. Protein distribution was detected by immunofluorescence experiment, and IFI6-interacting proteins were detected by immunoprecipitation (IP) combined with mass spectrometry. The global gene changes in IFI6-overexpressed skin cells after irradiation were detected by RNA-seq.RESULTS:mRNA expression profiling showed 50 upregulated and 13 down regulated genes and interferon alpha inducible protein 6 (IFI6) was top upregulated. Overexpression of IFI6 promoted cell proliferation and reduced cell apoptosis as well as ROS production following radiation, and conversely, increased the radiosensitivity of HaCaT and human skin fibroblast (WS1). IFI6 was translocated into nucleus in irradiated skin cells and the interacting relationship with mitochondrial single-stranded DNA-binding protein 1 (SSBP1), which could enhance the transcriptional activity of heat shock transcription factor 1 (HSF1).IFI6 augmented HSF1 activity following radiation in HaCaT and WS1 cells. RNA-seq analysis showed IFI6 modulated virus infection and cellular response to stress pathways, which may help to further explore how IFI6 regulate the transcriptional activity of HSF1.CONCLUSION:This study reveals that IFI6 is induced by ionizing radiation and confers radioprotection in skin cells.

PURPOSE:Esophageal cancer is one of the most common malignancies worldwide. Ubiquitin-dependent degradation of regulatory proteins reportedly plays a central role in diverse cellular processes. This study investigated the expression levels of ubiquitin in esophageal squamous cell carcinoma tissues and the functions of ubiquitin in the context of esophageal squamous cell carcinoma progression.METHODS:The expression of ubiquitin in esophageal squamous cell carcinoma and normal esophageal samples was determined via immunohistochemistry. Serum ubiquitin levels were determined by enzyme-linked immunosorbent assay. The association between serum ubiquitin level and clinicopathological factors was analyzed. Real-time PCR analysis was employed to measure the mRNA levels of the ubiquitin coding genes ubiquitin B and ubiquitin C. Proliferation assays, colony formation assays, and Transwell-based assays were used to determine the influence of ubiquitin on cell growth and cell invasion. Proteomic analysis was performed to identify the proteins associated with ubiquitin.RESULTS:Ubiquitin expression in esophageal squamous cell carcinoma tissues was markedly higher than that in normal and tumor adjacent tissues. The levels of ubiquitin in esophageal squamous cell carcinoma serum samples were significantly higher than those in healthy controls. Serum ubiquitin levels were correlated with tumor stage and lymph node metastasis. To silence the expression of ubiquitin, we knocked down the ubiquitin coding genes ubiquitin B and ubiquitin C in TE-1 and Eca-109 cells. Silencing ubiquitin resulted in the suppression of cell growth, chemoresistance, colony formation and cell migration in esophageal squamous cell carcinoma cells. Proteomic analysis in esophageal squamous cell carcinoma cells showed that knockdown of ubiquitin coding genes deregulated the expression of 159 proteins (92 were upregulated and 67 were downregulated) involved in multiple pathways. These proteins included ferritin light chain, ferritin heavy chain, cellular retinoic acid-binding protein 2, and DNA replication factor 1.CONCLUSION:Ubiquitin expression is upregulated in esophageal squamous cell carcinoma tissues and serum samples. Serum ubiquitin levels were correlated with tumor stage and lymph node metastasis. Downregulation of ubiquitin suppresses the aggressive phenotypes of esophageal squamous cell carcinoma cells by complex mechanisms; ubiquitin may represent a novel target for the treatment of esophageal squamous cell carcinoma.