ISG15 promotes esophageal squamous cell carcinoma tumorigenesis via c-MET/Fyn/β-catenin signaling pathway

USP8-Dependent Family Tyrosine Kinase Promotes the Malignant Progression of Esophageal Squamous Cell Carcinoma by Upregulating Protein Tyrosine Kinase 2 Expression

BACKGROUND

Esophageal squamous cell carcinoma (ESCC) is a lethal malignancy, and the molecular underpinnings of its aggressive behavior are not fully understood. FYN proto-oncogene, Src family tyrosine kinase (FYN) has been linked to cancer progression, yet its role in ESCC remains elusive. This study investigated the influence of FYN on ESCC malignancy.

METHODS

Quantitative real-time polymerase chain reaction was used to assess the mRNA expression of FYN, while western blotting and immunohistochemistry (IHC) assays were performed to detect the protein expression of FYN, ubiquitin specific peptidase 8 (USP8) and protein tyrosine kinase 2 (PTK2). Cell viability was measured with a cell counting kit-8 assay, and cell apoptosis was evaluated using flow cytometry.

RESULTS

FYN expression was increased in ESCC tissues and cells when compared with normal esophageal tissues and normal esophageal epithelial cells. Knockdown of FYN inhibited cell invasion, migration, stem-like traits, and glycolysis, while promoting apoptosis. USP8 was shown to stabilize FYN protein expression through its deubiquitinating activity in ESCC cells. Overexpression of FYN reversed the effects of USP8 silencing on the malignant phenotypes of ESCC cells in vitro and in vivo. FYN upregulated PTK2 expression in both TE1 and KYSE150 cell lines. Furthermore, PTK2 overexpression reversed the effects of FYN silencing on the malignant phenotypes of ESCC cells. Further, USP8 silencing-induced inhibitory effect on PTK2 protein expression was counteracted after FYN overexpression.

CONCLUSION

USP8-dependent FYN contributed to the malignant progression of ESCC by interacting with PTK2. Targeting this pathway may offer a novel therapeutic strategy for ESCC treatment.

ISG15 promotes tumor progression via IL6/JAK2/STAT3 signaling pathway in ccRCC

Although renal cell carcinoma (RCC) is a prevalent type of cancer, the most common pathological subtype, clear cell renal cell carcinoma (ccRCC), still has poorly understood molecular mechanisms of progression. Moreover, interferon-stimulated gene 15 (ISG15) is associated with various types of cancer; however, its biological role in ccRCC remains unclear.This study aimed to explore the role of ISG15 in ccRCC progression.ISG15 expression was upregulated in ccRCC and associated with poor prognosis. RNA sequence analysis and subsequent experiments indicated that ISG15 modulated IL6/JAK2/STAT3 signaling to promote ccRCC proliferation, migration, and invasion. Additionally, our animal experiments confirmed that sustained ISG15 knockdown reduced tumor growth rate in nude mice and promoted cell apoptosis. ISG15 modulates the IL6/JAK2/STAT3 pathway, making it a potential therapeutic target and prognostic biomarker for ccRCC.

A pathway-based computational framework for identification of a new modal of multi-omics biomarkers and its application in esophageal cancer

BACKGROUND

The pathway-based strategy has been recently proposed for identifying biomarkers with the advantages of higher biological interpretability and cross-data robustness than the conventional gene-based strategy. However, its utility in clinical applications has been limited due to the high computational complexity and ill-defined performance.

OBJECTIVE

The current study presents a machine learning-based computational framework using multi-omics data for identifying a new modal of biomarkers, called pathway-derived core biomarkers, which have the advantages of both gene-based and pathway-based biomarkers.

METHODS

Machine-learning methods and gene-pathway network were integrated to select the pathway-derived core biomarkers. Multiple machine-learning algorithms were used to construct and validate the diagnostic models of the biomarkers based on more than 1400 multi-omics clinical samples of esophageal squamous cell carcinoma (ESCC).

RESULTS

The results showed that the classifier models based on the new modal biomarkers achieved superior performance in the training datasets with an average AUC/accuracy of 0.98/0.95 and 0.89/0.81 for mRNAs and miRNA, respectively, higher than the currently known classifier models based on the conventional gene-based strategy and pathway-based strategy. In the testing cohorts, the AUC/accuracy increased by 6.1 %/7.3 % than the models based on the native gene-based biomarkers. The improved performance was further confirmed in independent validation cohorts. Specifically, the sensitivity/specificity increased by ∼3 % and the variance significantly decreased by ∼69 % compared with that of the native gene-based biomarkers. Importantly, the pathway-derived core biomarkers also recovered 45 % more previously reported biomarkers than the gene-based biomarkers and are more functionally relevant to the ESCC etiology (involved in 14 versus 7 pathways related with ESCC or other cancer), highlighting the cross-data robustness of this new modal of biomarkers via enhanced functional relevance.

CONCLUSIONS

The results demonstrated that the new modal of biomarkers not only have improved predicting performance and robustness, but also exhibit higher functional interpretability thus leading to the potential application in cancer diagnosis.

Unveiling the Multifaceted Roles of ISG15: From Immunomodulation to Therapeutic Frontiers

The Interferon Stimulated Gene 15 (ISG15), a unique Ubiquitin-like (Ubl) modifier exclusive to vertebrates, plays a crucial role in the immune system. Primarily induced by interferon (IFN) type I, ISG15 functions through diverse mechanisms: (i) covalent protein modification (ISGylation); (ii) non-covalent intracellular action; and (iii) exerting extracellular cytokine activity. These various roles highlight its versatility in influencing numerous cellular pathways, encompassing DNA damage response, autophagy, antiviral response, and cancer-related processes, among others. The well-established antiviral effects of ISGylation contrast with its intriguing dual role in cancer, exhibiting both suppressive and promoting effects depending on the tumour type. The multifaceted functions of ISG15 extend beyond intracellular processes to extracellular cytokine signalling, influencing immune response, chemotaxis, and anti-tumour effects. Moreover, ISG15 emerges as a promising adjuvant in vaccine development, enhancing immune responses against viral antigens and demonstrating efficacy in cancer models. As a therapeutic target in cancer treatment, ISG15 exhibits a double-edged nature, promoting or suppressing oncogenesis depending on the tumour context. This review aims to contribute to future studies exploring the role of ISG15 in immune modulation and cancer therapy, potentially paving the way for the development of novel therapeutic interventions, vaccine development, and precision medicine.

Increase of ISG15 in psoriasis lesions and its promotion of keratinocyte proliferation via the Hif-1α signalling pathway

Psoriasis is a frequent chronic, recurrent and immune-mediated inflammatory skin disease, whose pathogenesis remains unclear at present. The role of antiviral protein in the pathogenesis of psoriasis is the focus of current research. Interferon stimulated gene 15 (ISG15) is an important antiviral protein. In this study, the expression of ISG15 saw a significant increase through the immunohistochemical detection of imiquimod (IMQ)-induced mice. In the psoriasis cell model, a remarkable increase also occurred in the expression of ISG15. In this study, it was found that the cell cycle was blocked in G1/S conversion, and a reduction took place in the proliferation of keratinocytes and the expression of a cell cycle-related protein-cyclin D1 after the knockout of ISG15 in the psoriasis cell model. After that, messenger ribonucleic acid (mRNA) sequencing and Gene Ontology/Kyoto Encyclopedia of Genes and Genomes (GO/KEGG) analysis indicated its close association with the hypoxia inducible factor-1α (HIF-1α) signalling pathway. Western blot showed a decrease in the expression of HIF-1α and vascular endothelial growth factor C (VEGFC) after the knockout of the ISG15 gene. The rescue experiment verified that ISG15 promotes the proliferation of keratinocytes by regulating the HIF-1α signalling pathway. It was concluded that psoriasis cells and mouse models witnessed the increased expression of ISG15. In psoriasis, knocking out ISG15 inhibits the proliferation of keratinocytes and blocks the cell cycle. Besides, ISG15 promotes the proliferation of keratinocytes through the HIF-1α signalling pathway.

Protein ISGylation: a posttranslational modification with implications for malignant neoplasms

Interferon (IFN)-stimulated gene 15 (ISG15) is a member of the ubiquitin-like (UBL) protein family that can modify specific proteins via a catalytic process called ISGylation. This posttranslational modification can modulate the stability of the ISGylated proteins and protein-protein interactions. Some proteins modified by ISG15 have been identified in malignant neoplasms, suggesting the functional relevance of ISGylation in cancer. This review discusses the ISGylated proteins reported in malignant neoplasms that suggest the potential of ISG15 as a biomarker and therapeutic target in cancer.

Identification of Potential Biomarkers Using Integrative Approach: A Case Study of ESCC

This paper presents a consensus-based approach that incorporates three microarray and three RNA-Seq methods for unbiased and integrative identification of differentially expressed genes (DEGs) as potential biomarkers for critical disease(s). The proposed method performs satisfactorily on two microarray datasets (GSE20347 and GSE23400) and one RNA-Seq dataset (GSE130078) for esophageal squamous cell carcinoma (ESCC). Based on the input dataset, our framework employs specific DE methods to detect DEGs independently. A consensus based function that first considers DEGs common to all three methods for further downstream analysis has been introduced. The consensus function employs other parameters to overcome information loss. Differential co-expression (DCE) and preservation analysis of DEGs facilitates the study of behavioral changes in interactions among DEGs under normal and diseased circumstances. Considering hub genes in biologically relevant modules and most GO and pathway enriched DEGs as candidates for potential biomarkers of ESCC, we perform further validation through biological analysis as well as literature evidence. We have identified 25 DEGs that have strong biological relevance to their respective datasets and have previous literature establishing them as potential biomarkers for ESCC. We have further identified 8 additional DEGs as probable potential biomarkers for ESCC, but recommend further in-depth analysis.

Targeting the miR-34a/LRPPRC/MDR1 axis collapse the chemoresistance in P53 inactive colorectal cancer

P53 mutation is an important cause of chemoresistance in colorectal cancer (CRC). The investigation and identification of the downstream targets and underlying molecular mechanism of chemoresistance induced by P53 abnormalities are therefore of great clinical significance. In this study, we demonstrated and reported for the first time that leucine-rich pentatricopeptide repeat-containing protein (LRPPRC) is a key functional downstream factor and therapeutic target for P53 mutation-induced chemoresistance. Due to its RNA binding function, LRPPRC specifically bound to the mRNA of multidrug resistance 1 (MDR1), increasing MDR1 mRNA stability and protein expression. In normal cells, P53 induced by chemotherapy inhibited the expression of LRPPRC via miR-34a and in turn reduced the expression of MDR1. However, chemotherapy-induced P53/miR-34a/LRPPRC/MDR1 signalling pathway activation was lost when P53 was mutated. Additionally, the accumulated LRPPRC and MDR1 promoted drug resistance. Most importantly, gossypol-acetic acid (GAA) was recently reported by our team as the first specific inhibitor of LRPPRC. In CRC cells with P53 mutation, GAA effectively induced degradation of the LRPPRC protein and reduced chemoresistance. Both in vivo and in vitro experiments revealed that combination chemotherapy with GAA and 5-fluorouracil (5FU) yielded improved treatment outcomes. In this study, we reported a novel mechanism and target related to P53-induced drug resistance and provided corresponding interventional strategies for the precision treatment of CRC.

The diverse repertoire of ISG15: more intricate than initially thought

ISG15, the product of interferon (IFN)-stimulated gene 15, is the first identified ubiquitin-like protein (UBL), which plays multifaceted roles not only as a free intracellular or extracellular molecule but also as a post-translational modifier in the process of ISG15 conjugation (ISGylation). ISG15 has only been identified in vertebrates, indicating that the functions of ISG15 and its conjugation are restricted to higher eukaryotes and have evolved with IFN signaling. Despite the highlighted complexity of ISG15 and ISGylation, it has been suggested that ISG15 and ISGylation profoundly impact a variety of cellular processes, including protein translation, autophagy, exosome secretion, cytokine secretion, cytoskeleton dynamics, DNA damage response, telomere shortening, and immune modulation, which emphasizes the necessity of reassessing ISG15 and ISGylation. However, the underlying mechanisms and molecular consequences of ISG15 and ISGylation remain poorly defined, largely due to a lack of knowledge on the ISG15 target repertoire. In this review, we provide a comprehensive overview of the mechanistic understanding and molecular consequences of ISG15 and ISGylation. We also highlight new insights into the roles of ISG15 and ISGylation not only in physiology but also in the pathogenesis of various human diseases, especially in cancer, which could contribute to therapeutic intervention in human diseases.

Interferon‑stimulated gene 15 promotes progression of endometrial carcinoma and weakens antitumor immune response

Endometrial carcinoma (EC) is one of the most common gynecological cancers with a poor prognosis. Therefore, clarifying the details of the molecular mechanisms is of great importance for EC diagnosis and clinical management. Interferon-stimulated gene 15 (ISG15) plays an important role in the development of various cancers. However, its role in EC remains unclear. High ISG15 expression was observed in EC, which was associated with poor clinical outcomes and pathological stage of patients with EC, thus representing a promising marker for EC progression. Further exploratory analysis revealed that the elevated ISG15 levels in EC were driven by aberrant DNA methylation, independent of copy number variation and specific transcription factor aberrations. Accordingly, knockdown of ISG15 by small interfering RNA attenuated the malignant cellular phenotype of EC cell lines, including proliferation and colony formation in vitro. Finally, investigation of the molecular mechanisms indicated that ISG15 promoted the cell cycle G1/S transition in EC. Furthermore, ISG15 promoted EC progression by activating the MYC proto-oncogene protein signaling pathway. Moreover, ECs with high levels of ISG15 harbored a more vital immune escape ability, evidenced not only by significantly less invasive CD8⁺ T cells, but also higher expression of T cell inhibitory factors, such as programmed death-ligand 1. These results suggest a tumor-promoting role of ISG15 in EC, which may be a promising marker for diagnosis, prognosis and therapeutic immunity.

Free ISG15 and protein ISGylation emerging in SARS-CoV-2 infection

Interferon-simulated gene 15 (ISG15) belongs to the family of ubiquitin-like proteins. ISG15 acts as a cytokine and modifies proteins through ISGylation. This posttranslational modification has been associated with antiviral and immune response pathways. In addition, it is known that the genome of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) encodes proteases critical for viral replication. Consequently, these proteases are also central in the progression of coronavirus disease 2019 (COVID-19). Interestingly, the protease SARS-CoV-2-PLpro removes ISG15 from ISGylated proteins such as IRF3 and MDA5, affecting immune and antiviral defense from the host. Here, the implications of ISG15, ISGylation, and generation of SARS-CoV-2-PLpro inhibitors in SARS-CoV-2 infection are discussed.

ISG15 and ISGylation in Human Diseases

Type I Interferons (IFNs) induce the expression of >500 genes, which are collectively called ISGs (IFN-stimulated genes). One of the earliest ISGs induced by IFNs is ISG15 (Interferon-Stimulated Gene 15). Free ISG15 protein synthesized from the ISG15 gene is post-translationally conjugated to cellular proteins and is also secreted by cells into the extracellular milieu. ISG15 comprises two ubiquitin-like domains (UBL1 and UBL2), each of which bears a striking similarity to ubiquitin, accounting for its earlier name ubiquitin cross-reactive protein (UCRP). Like ubiquitin, ISG15 harbors a characteristic β-grasp fold in both UBL domains. UBL2 domain has a conserved C-terminal Gly-Gly motif through which cellular proteins are appended via an enzymatic cascade similar to ubiquitylation called ISGylation. ISG15 protein is minimally expressed under physiological conditions. However, its IFN-dependent expression is aberrantly elevated or compromised in various human diseases, including multiple types of cancer, neurodegenerative disorders (Ataxia Telangiectasia and Amyotrophic Lateral Sclerosis), inflammatory diseases (Mendelian Susceptibility to Mycobacterial Disease (MSMD), bacteriopathy and viropathy), and in the lumbar spinal cords of veterans exposed to Traumatic Brain Injury (TBI). ISG15 and ISGylation have both inhibitory and/or stimulatory roles in the etiology and pathogenesis of human diseases. Thus, ISG15 is considered a “double-edged sword” for human diseases in which its expression is elevated. Because of the roles of ISG15 and ISGylation in cancer cell proliferation, migration, and metastasis, conferring anti-cancer drug sensitivity to tumor cells, and its elevated expression in cancer, neurodegenerative disorders, and veterans exposed to TBI, both ISG15 and ISGylation are now considered diagnostic/prognostic biomarkers and therapeutic targets for these ailments. In the current review, we shall cover the exciting journey of ISG15, spanning three decades from the bench to the bedside.

Advances and challenges in the treatment of esophageal cancer

Esophageal cancer (EC) is one of the most common cancers with high morbidity and mortality rates. EC includes two histological subtypes, namely esophageal squamous cell carcinoma (ESCC) and esophageal adenocarcinoma (EAC). ESCC primarily occurs in East Asia, whereas EAC occurs in Western countries. The currently available treatment strategies for EC include surgery, chemotherapy, radiation therapy, molecular targeted therapy, and combinations thereof. However, the prognosis remains poor, and the overall five-year survival rate is very low. Therefore, achieving the goal of effective treatment remains challenging. In this review, we discuss the latest developments in chemotherapy and molecular targeted therapy for EC, and comprehensively analyze the application prospects and existing problems of immunotherapy. Collectively, this review aims to provide a better understanding of the currently available drugs through in-depth analysis, promote the development of new therapeutic agents, and eventually improve the treatment outcomes of patients with EC.

TROP2 modulates the progression in papillary thyroid carcinoma

Background: Tumor-associated calcium signal transducer 2 (TROP2) is over expressed in various kinds of human cancers and plays important roles in the proliferation, invasion and metastasis of tumor cells. However, the expression and molecular mechanism of TROP2 in thyroid papillary carcinoma (PTC) are unclear. Methods: The expressions of TROP2 in PTC and control tissue were detected by real-time reverse transcription polymerase chain reaction (RT-PCR) and immunohistochemistry. The proliferation and invasion of PTC cell lines were examined by cell cloning and transwell assays. RNA sequencing analysis and public data analysis were assessed to investigate the potential mechanisms of TROP2 in PTC. Gene correlation analysis was conducted to explore the association between TROP2 and the related gene ISG15 in patients with PTC. Results: The expression of TROP2 was significantly higher in PTC than control. The high expression of TROP2 protein was associated with lymph node metastasis, tumor size and capsular infiltration (P<0.05). SiRNA-mediated TROP2 gene expression silencing can significantly inhibit proliferation and migration of PTC cells. ISG15 decreased in TROP2 siRNA PTC cells and increased in PTC patients significantly. There was a significant correlation between the expression of TROP2 and ISG15 in PTC patients. TROP2 interacted directly with ATP6V1A, CEBPA and SOX5 and then further interacted with the immune genes. TROP2 expression and tumor-infiltrating immune cells were also correlated in thyroid cancer microenvironment. Conclusions: TROP2 promotes the development of PTC. TROP2 expression was correlated with ISG15 and tumor-infiltrating immune cells in thyroid cancer.

ISG15 is downregulated by KLF12 and implicated in maintenance of cancer stem cell-like features in cisplatin-resistant ovarian cancer

Drug resistance is often developed during clinical chemotherapy of ovarian cancers. The ubiquitin‐like protein interferon‐stimulated gene 15 (ISG15) is possibly dependent on tumour context to promote or suppress progression of various tumours. The ubiquitin‐like protein interferon‐stimulated gene 15 (ISG15) was decreased in cisplatin‐resistant ovarian cancer cells. The current study identified that both ectopic wild type and nonISGylatable mutant ISG15 expression inhibited CSC‐like phenotypes of cisplatin‐resistant ovarian cancer cells. Moreover, ectopic ISG15 expression suppressed tumour formation in nude mice. In addition, ISG15 downregulation promoted CSC‐like features of cisplatin‐sensitive ovarian cancer cells. Furthermore, low ISG15 expression was associated with poor prognosis in patients with ovarian cancer. Transcriptional repressor Krüppel‐like factor 12 (KLF12) downregulated ISG15 in cisplatin‐resistant cells. Our data indicated that downregulating ISG15 expression, via weakening effect of KLF12, might be considered as new therapeutic strategy to inhibit CSC phenotypes in the treatment of cisplatin‐resistant ovarian cancer.

MEX3A is upregulated in esophageal squamous cell carcinoma (ESCC) and promotes development and progression of ESCC through targeting CDK6

Esophageal squamous cell carcinoma (ESCC) is one of the most commonly diagnosed malignant tumors worldwide and identified as a serious threat to human health. The role of MEX3A in ESCC remains unclear. In this study, we found that MEX3A was upregulated in tumor tissues of ESCC and positively associated with more advanced tumor stage, higher risk of lymphatic metastasis and poor prognosis. The downregulation of MEX3A in ESCC cell lines could induce inhibition of cell proliferation, colony formation, cell migration, and the promotion of cell apoptosis, while MEX3A overexpression exhibited opposite effects. In vivo experiments also verified the inhibition of ESCC induced by MEX3A knockdown. Moreover, we identified CDK6 as a potential target of MEX3A, which was also upregulated in ESCC. Further studies demonstrated that knockdown of CDK6 showed similar effects on the development of ESCC with MEX3A. More importantly, it was illustrated that CDK6 knockdown could alleviate the promotion effects of MEX3A overexpression on ESCC. In conclusion, MEX3A was identified as a tumor promotor in the development and progression of ESCC by targeting CDK6, which may be considered as a novel prognostic indicator and therapeutic target in treatment of ESCC.

Identification of Subtype-Specific Metastasis-Related Genetic Signatures in Sarcoma

Background: Sarcomas are heterogeneous rare malignancies constituting approximately 1% of all solid cancers in adults and including more than 70 histological and molecular subtypes with different pathological and clinical development characteristics.

Method: We identified prognostic biomarkers of sarcomas by integrating clinical information and RNA-seq data from TCGA and GEO databases. In addition, results obtained from cell cycle, cell migration, and invasion assays were used to assess the capacity for Tanespimycin to inhibit the proliferation and metastasis of sarcoma.

Results: Sarcoma samples (N = 536) were divided into four pathological subtypes including DL (dedifferentiated liposarcoma), LMS (leiomyosarcoma), UPS (undifferentiated pleomorphic sarcomas), and MFS (myxofibrosarcoma). RNA-seq expression profile data from the TCGA dataset were used to analyze differentially expressed genes (DEGs) within metastatic and non-metastatic samples of these four sarcoma pathological subtypes with DEGs defined as metastatic-related signatures (MRS). Prognostic analysis of MRS identified a group of genes significantly associated with prognosis in three pathological subtypes: DL, LMS, and UPS. ISG15, NUP50, PTTG1, SERPINE1, and TSR1 were found to be more likely associated with adverse prognosis. We also identified Tanespimycin as a drug exerting inhibitory effects on metastatic LMS subtype and therefore can serve a potential treatment for this type of sarcoma.

Conclusions: These results provide new insights into the pathogenesis, diagnosis, treatment, and prognosis of sarcomas and provide new directions for further study of sarcoma.

Neferine induces apoptosis by modulating the ROS‑mediated JNK pathway in esophageal squamous cell carcinoma

Current treatments for esophageal squamous cell carcinoma (ESCC) have limited efficacy. Therefore, the development of novel therapeutic targets to effectively manage the disease and boost survival rates is imperative Neferine, a natural product extracted from Nelumbo nucifera (lotus) leaves, has been revealed to inhibit the growth of hepatocarcinoma, breast cancer and lung cancer cells. However, its effect on ESCC is unknown. In the present study, it was revealed that neferine exerted anti‑proliferative effects in ESCC. It was also revealed that it triggered arrest of the G2/M phase and enhanced apoptosis of ESCC cell lines. Moreover, its ability to trigger accumulation of reactive oxygen species (ROS) and activate the c‑Jun N‑terminal kinase (JNK) pathway was demonstrated. Further study revealed how N‑acetyl cysteine (NAC), a ROS inhibitor, attenuated these effects, demonstrating that ROS and JNK inhibitors mediated a marked reversal of neferine‑triggered cell cycle arrest and apoptosis in ESCC cells. Finally, it was revealed that neferine was involved in the inhibition of Nrf2, an antioxidant factor. Collectively, these findings demonstrated the antitumor effect of neferine in ESCC, through the ROS‑mediated JNK pathway and inhibition of Nrf2, indicating its potential as a target for development of novel and effective therapeutic agents against ESCC.

Intestinal Epithelial Cells Express Immunomodulatory ISG15 During Active Ulcerative Colitis and Crohn's Disease

BACKGROUND AND AIMS

Intestinal epithelial cells [IECs] secrete cytokines that recruit immune cells to the mucosa and regulate immune responses that drive inflammation in inflammatory bowel disease [IBD]. However, experiments in patient-derived IEC models are still scarce. Here, we aimed to investigate how innate immunity and IEC-specific pattern recognition receptor [PRR] signalling can be involved in an enhanced type I interferon [IFN] gene signature observed in colon epithelium of patients with active IBD, with a special focus on secreted ubiquitin-like protein ISG15.

METHODS

Gene and protein expression in whole mucosa biopsies and in microdissected human colonic epithelial lining, in HT29 human intestinal epithelial cells and primary 3D colonoids treated with PRR-ligands and cytokines, were detected by transcriptomics, in situ hybridisation, immunohistochemistry, western blots, and enzyme-linked immunosorbent assay [ELISA]. Effects of IEC-secreted cytokines were examined in human peripheral blood mononuclear cells [PBMCs] by multiplex chemokine profiling and ELISA.

RESULTS

The type I IFN gene signature in human mucosal biopsies was mimicked in Toll-like receptor TLR3 and to some extent tumour necrosis factor [TNF]-treated human IECs. In intestinal biopsies, ISG15 expression correlated with expression of the newly identified receptor for extracellular ISG15, LFA-1 integrin. ISG15 was expressed and secreted from HT29 cells and primary 3D colonoids through both JAK1-pSTAT-IRF9-dependent and independent pathways. In experiments using PBMCs, we show that ISG15 releases IBD-relevant proinflammatory cytokines such as CXCL1, CXCL5, CXCL8, CCL20, IL1, IL6, TNF, and IFNγ.

CONCLUSIONS

ISG15 is secreted from primary IECs upon extracellular stimulation, and mucosal ISG15 emerges as an intriguing candidate for immunotherapy in IBD.

DCLK1 inhibition attenuates tumorigenesis and improves chemosensitivity in esophageal squamous cell carcinoma by inhibiting β-catenin/c-Myc signaling

Doublecortin-like kinase 1 (DCLK1) is involved in tumorigenesis, tumor growth and metastasis, and epithelial-to-mesenchymal transition in many digestive tract tumors. It is reportedly highly expressed in Barrett's esophagus and esophageal adenocarcinoma, but its effects on the occurrence and progression of esophageal squamous cell carcinoma (ESCC) remain unclear. In this study, real-time PCR and western blot analysis confirmed significant upregulation of DCLK1 expression in human ESCC tissues and cell lines. CCK-8 assay showed that transfection with siRNA against DCLK1 (si-DCLK1) markedly inhibited cell proliferation and colony formation in the ESCC cell lines Eca109 and TE1. Transwell assay revealed that si-DCLK1 transfection inhibited the migratory and invasive capacities of Eca109 and TE1 cells. Moreover, si-DCLK1 increased the chemosensitivity of these cells to cisplatin, as indicated by inhibited cell viability and colony formation, and increased ROS and apoptosis in cisplatin-treated cells. Western blot assay revealed that expression of nuclear β-catenin and c-Myc was significantly increased in ESCC tissues and that si-DCLK1 markedly downregulated nuclear β-catenin and c-Myc in Eca109 cells. Treatment with lithium chloride, an activator of β-catenin signaling, partially abolished the si-DCLK1-induced inhibition of proliferation, migration, invasion, and chemoresistance of ESCC cells. These findings suggest that knockdown of DCLK1 may inhibit the progression of ESCC by regulating proliferation, migration, invasion, and chemosensitivity via suppressing the β-catenin/c-Myc pathway, supporting a promising therapeutic target against ESCC.

ISG15 suppresses translation of ABCC2 via ISGylation of hnRNPA2B1 and enhances drug sensitivity in cisplatin resistant ovarian cancer cells

Cisplatin-based chemotherapies have long been considered as a standard chemotherapy in ovarian cancer. However, cisplatin resistance restricts beneficial therapy for patients with ovarian cancer. The ubiquitin-like protein interferon-stimulated gene 15 (ISG15) encodes a 15-kDa protein, that is implicated in the post-translational modification of diverse proteins. In this work, we found that ISG15 was downregulated in cisplatin resistant tissues and cell lines of ovarian cancer. Functional studies demonstrated that overexpression of wild type (WT) ISG15, but not nonISGylatable (Mut) ISG15 increased cell responses to cisplatin in resistant ovarian cancer cells. Furthermore, we found that WT ISG15 decreased ABCC2 expression at the protein level. Importantly, overexpression of ABCC2 blocked sensitizing effect of ISG15 on cisplatin. In addition, we identified that hnRNPA2B1 was recruited to 5'UTR of ABCC2 mRNA and promoted its translation, which was blocked by ISG15. We further demonstrated that hnRNPA2B1 could be ISGylated, and ISGylation blocked its recruitment to ABCC2 mRNA, thereby suppressed translation of ABCC2. Altogether, our data support targeting ISG15 might be a potential therapeutic strategy for patients with cisplatin-resistant ovarian cancer.