Whole-genome sequencing of 508 patients identifies key molecular features associated with poor prognosis in esophageal squamous cell carcinoma. Cell Res. 2020;30:902-913. [PMID: 32398863 PMCID: PMC7608103 DOI: 10.1038/s41422-020-0333-6]

TRIM29 hypermethylation drives esophageal cancer progression via suppression of ZNF750

Esophageal cancer (ESCA) is the seventh most frequent and deadly neoplasm. Due to the lack of early diagnosis and high invasion/metastasis, the prognosis of ESCA remains very poor. Herein, we identify skin-related signatures as the most deficient signatures in invasive ESCA, which are regulated by the transcription factor ZNF750. Of note, we find that TRIM29 level strongly correlated with the expression of many genes in the skin-related signatures, including ZNF750. TRIM29 is significantly down-regulated due to hypermethylation of its promoter in both ESCA and precancerous lesions compared to normal tissues. Low TRIM29 expression and high methylation levels of its promoter are associated with malignant progression and poor clinical outcomes in ESCA patients. Functionally, TRIM29 overexpression markedly hinders proliferation, migration, invasion, and epithelial-mesenchymal transition of esophageal cancer cells, whereas opposing results are observed when TRIM29 is silenced in vitro. In addition, TRIM29 inhibits metastasis in vivo. Mechanistically, TRIM29 downregulation suppresses the expression of the tumor suppressor ZNF750 by activating the STAT3 signaling pathway. Overall, our study demonstrates that TRIM29 expression and its promoter methylation status could be potential early diagnostic and prognostic markers. It highlights the role of the TRIM29-ZNF750 signaling axis in modulating tumorigenesis and metastasis of esophageal cancer.

RPS15 interacted with IGF2BP1 to promote esophageal squamous cell carcinoma development via recognizing m6A modification

Increased rates of ribosome biogenesis have been recognized as hallmarks of many cancers and are associated with poor prognosis. Using a CRISPR synergistic activation mediator (SAM) system library targeting 89 ribosomal proteins (RPs) to screen for the most oncogenic functional RPs in human esophageal squamous cell carcinoma (ESCC), we found that high expression of RPS15 correlates with malignant phenotype and poor prognosis of ESCC. Gain and loss of function models revealed that RPS15 promotes ESCC cell metastasis and proliferation, both in vitro and in vivo. Mechanistic investigations demonstrated that RPS15 interacts with the K homology domain of insulin-like growth factor 2 mRNA-binding protein 1 (IGF2BP1), which recognizes and directly binds the 3'-UTR of MKK6 and MAPK14 mRNA in an m⁶A-dependent manner, and promotes translation of core p38 MAPK pathway proteins. By combining targeted drug virtual screening and functional assays, we found that folic acid showed a therapeutic effect on ESCC by targeting RPS15, which was augmented by the combination with cisplatin. Inhibition of RPS15 by folic acid, IGF2BP1 ablation, or SB203580 treatment were able to suppress ESCC metastasis and proliferation via the p38 MAPK signaling pathway. Thus, RPS15 promotes ESCC progression via the p38 MAPK pathway and RPS15 inhibitors may serve as potential anti-ESCC drugs.

A fibroblast-associated signature predicts prognosis and immunotherapy in esophageal squamous cell cancer

Background

Current paradigms of anti-tumor therapies are not qualified to evacuate the malignancy ascribing to cancer stroma's functions in accelerating tumor relapse and therapeutic resistance. Cancer-associated fibroblasts (CAFs) has been identified significantly correlated with tumor progression and therapy resistance. Thus, we aimed to probe into the CAFs characteristics in esophageal squamous cancer (ESCC) and construct a risk signature based on CAFs to predict the prognosis of ESCC patients.

Methods

The GEO database provided the single-cell RNA sequencing (scRNA-seq) data. The GEO and TCGA databases were used to obtain bulk RNA-seq data and microarray data of ESCC, respectively. CAF clusters were identified from the scRNA-seq data using the Seurat R package. CAF-related prognostic genes were subsequently identified using univariate Cox regression analysis. A risk signature based on CAF-related prognostic genes was constructed using Lasso regression. Then, a nomogram model based on clinicopathological characteristics and the risk signature was developed. Consensus clustering was conducted to explore the heterogeneity of ESCC. Finally, PCR was utilized to validate the functions that hub genes play on ESCC.

Results

Six CAF clusters were identified in ESCC based on scRNA-seq data, three of which had prognostic associations. A total of 642 genes were found to be significantly correlated with CAF clusters from a pool of 17080 DEGs, and 9 genes were selected to generate a risk signature, which were mainly involved in 10 pathways such as NRF1, MYC, and TGF-Beta. The risk signature was significantly correlated with stromal and immune scores, as well as some immune cells. Multivariate analysis demonstrated that the risk signature was an independent prognostic factor for ESCC, and its potential in predicting immunotherapeutic outcomes was confirmed. A novel nomogram integrating the CAF-based risk signature and clinical stage was developed, which exhibited favorable predictability and reliability for ESCC prognosis prediction. The consensus clustering analysis further confirmed the heterogeneity of ESCC.

Conclusion

The prognosis of ESCC can be effectively predicted by CAF-based risk signatures, and a comprehensive characterization of the CAF signature of ESCC may aid in interpreting the response of ESCC to immunotherapy and offer new strategies for cancer treatment.

Co-Expression of Chromatin Assembly Factor 1 Subunit A and Proliferating Cell Nuclear Antigen Is a Prognostic Biomarker of Esophageal Cancer

(1) Background: Esophageal cancer (EC) is an important global health challenge. Due to the lack of necessary biomarkers and therapeutic targets, the survival of EC patients is poor. The EC proteomic data of 124 patients recently published by our group provides a database for research in this field. (2) Methods: Bioinformatics analysis was used to identify DNA replication and repair-related proteins in EC. Proximity ligation assay, colony formation assay, DNA fiber assay, and flow cytometry were used to study the effects of related proteins on EC cells. Kaplan-Meier survival analysis was used to evaluate the relationship between gene expression and the survival time of EC patients. (3) Results: Chromatin assembly factor 1 subunit A (CHAF1A) was highly correlated with proliferating cell nuclear antigen (PCNA) expression in EC. CHAF1A and PCNA colocalized in the nucleus of EC cells. Compared with the knockdown of CHAF1A or PCNA alone, the double knockdown of CHAF1A and PCNA could significantly inhibit EC cell proliferation. Mechanistically, CHAF1A and PCNA synergistically accelerated DNA replication and promoted S-phase progression. EC patients with high expression of both CHAF1A and PCNA had a worse survival rate. (4) Conclusion: we identify CHAF1A and PCNA as key cell cycle-related proteins leading to the malignant progression of EC, and these proteins could serve as important prognostic biomarkers and targets for EC.

Identification and validation of cuproptosis related genes and signature markers in bronchopulmonary dysplasia disease using bioinformatics analysis and machine learning

BACKGROUND

Bronchopulmonary Dysplasia (BPD) has a high incidence and affects the health of preterm infants. Cuproptosis is a novel form of cell death, but its mechanism of action in the disease is not yet clear. Machine learning, the latest tool for the analysis of biological samples, is still relatively rarely used for in-depth analysis and prediction of diseases.

METHODS AND RESULTS

First, the differential expression of cuproptosis-related genes (CRGs) in the GSE108754 dataset was extracted and the heat map showed that the expression of NFE2L2 gene was significantly higher in the control group whereas the expression of GLS gene was significantly higher in the treatment group. Chromosome location analysis showed that both the genes were positively correlated and associated with chromosome 2. The results of immune infiltration and immune cell differential analysis showed differences in the four immune cells, significantly in Monocytes cells. Five new pathways were analyzed through two subgroups based on consistent clustering of CRG expression. Weighted correlation network analysis (WGCNA) set the screening condition to the top 25% to obtain the disease signature genes. Four machine learning algorithms: Generalized Linear Models (GLM), Random Forest (RF), Support Vector Machine (SVM), and Extreme Gradient Boosting (XGB) were used to screen the disease signature genes, and the final five marker genes for disease prediction. The models constructed by GLM method were proved to be more accurate in the validation of two datasets, GSE190215 and GSE188944.

CONCLUSION

We eventually identified two copper death-associated genes, NFE2L2 and GLS. A machine learning model-GLM was constructed to predict the prevalence of BPD disease, and five disease signature genes NFATC3, ERMN, PLA2G4A, MTMR9LP and LOC440700 were identified. These genes that were bioinformatics analyzed could be potential targets for identifying BPD disease and treatment.

Mutant p53 activates hnRNPA2B1-AGAP1-mediated exosome formation to promote esophageal squamous cell carcinoma progression

p53 mutations predispose cancer cell development, promote their survival and metastasis, and lead to ineffective therapeutic responses and unfavorable prognosis. No drug that abrogates the oncogenic functions of mutant p53 has been approved for cancer treatment. Here, we performed whole-genome sequencing of 663 esophageal squamous cell carcinoma (ESCC) tumor tissues and paired normal tissues. The results indicated that ESCC samples from our cohort had a more dispersed distribution of TP53 mutants and a higher proportion of nonsense mutants than European and American ESCC samples in the International Agency for Research on Cancer (IARC) database. The most frequent p53 mutations disrupt the inhibition of proliferation, migration, and invasion mediated by wild-type p53 in ESCC. Furthermore, p53 mutations alter its protein nucleoplasmic localization and protein stability. The p53 mutation G245S (p53-G245S) interacts with heterogeneous nuclear ribonucleoprotein A2B1 (hnRNPA2B1) to increase protein translation of phosphatidylinositol-dependent Arf GAP (AGAP1) by promoting AGAP1 mRNA stability. AGAP1 promotes cancer cell proliferation and metastasis by enhancing exosome formation. Furthermore, we explored the combination of the HSP90 inhibitor HSP90i and the AGAP1 inhibitor QS11 could inhibit ESCC cell proliferation and metastasis. Thus, the p53-G245S/hnRNPA2B1/AGAP1 axis promotes ESCC progression by enhancing exosome formation, and the combination of an HSP90 inhibitor and an AGAP1 inhibitor may serve as a potential therapeutic strategy.

An immunogenic and oncogenic feature-based classification for chemotherapy plus PD-1 blockade in advanced esophageal squamous cell carcinoma

Although chemotherapy plus PD-1 blockade (chemo+anti-PD-1) has become the standard first-line therapy for advanced esophageal squamous cell carcinoma (ESCC), reliable biomarkers for this regimen are lacking. Here we perform whole-exome sequencing on tumor samples from 486 patients of the JUPITER-06 study and develop a copy number alteration-corrected tumor mutational burden that depicts immunogenicity more precisely and predicts chemo+anti-PD-1 efficacy. We identify several other favorable immunogenic features (e.g., HLA-I/II diversity) and risk oncogenic alterations (e.g., PIK3CA and TET2 mutation) associated with chemo+anti-PD-1 efficacy. An esophageal cancer genome-based immuno-oncology classification (EGIC) scheme incorporating these immunogenic features and oncogenic alterations is established. Chemo+anti-PD-1 achieves significant survival improvements in EGIC1 (immunogenic feature-favorable and oncogenic alteration-negative) and EGIC2 (either immunogenic feature-favorable or oncogenic alteration-negative) subgroups, but not the EGIC3 subgroup (immunogenic feature-unfavorable and oncogenic alteration-positive). Thus, EGIC may guide future individualized treatment strategies and inform mechanistic biomarker research for chemo+anti-PD-1 treatment in patients with advanced ESCC.

Phosphorylation of AKT by lysyl oxidase-like 2 activates the PI3K/AKT signaling pathway to promote proliferation, invasion and metastasis in esophageal squamous carcinoma

OBJECTIVE

Esophageal squamous cell carcinoma (ESCC) is a common and aggressive malignancy of the gastrointestinal tract for which therapeutic options are scarce. This study screens for LOXL2, a key gene in ESCC, and explains the molecular mechanism by which it promotes the progression of ESCC.

METHODS

Immunohistochemical staining was performed to detect the expression level of LOXL2 in ESCC tissues and paraneoplastic tissues. CCK-8 and Transwell assays were performed to assess the effects of LOXL2 knockdown and overexpression on the proliferation, apoptosis, migration and invasion ability of ESCC cells. High-throughput sequencing analysis screens for molecular mechanisms of action by which LOXL2 promotes ESCC progression. Western blotting and qRT-PCR were used to determine the expression levels of relevant markers.

RESULTS

LOXL2 is positively expressed in ESCC and highly correlated with poor prognosis. Silencing LOXL2 significantly inhibited the proliferation, migration and invasive ability of ESCC cells, whereas overexpression showed the opposite phenotype. High-throughput sequencing suggested that LOXL2-associated differentially expressed genes were highly enriched in the PI3K/AKT signaling pathway. In vitro cellular assays confirmed that silencing LOXL2 significantly reduced PI3K, p-AKT^Thr308 and p-AKT^Ser473 gene and protein expression levels, while overexpression increased all three gene and protein levels, while AKT gene and protein expression levels were not significantly different.

CONCLUSION

This study found that LOXL2 may regulate the PI3K/AKT signaling pathway and exert protumor effects on ESCC cells through phosphorylation of AKT. LOXL2 may be a key clinical warning biomarker or therapeutic target for ESCC.

Multi-omics analysis uncovers tumor ecosystem dynamics during neoadjuvant toripalimab plus nab-paclitaxel and S-1 for esophageal squamous cell carcinoma: a single-center, open-label, single-arm phase 2 trial

BACKGROUND

Immune checkpoint inhibitors combined with chemotherapy as a neoadjuvant therapy have been applied to the treatment of esophageal squamous cell carcinoma (ESCC). However, the optimal regimen needs to be further explored, particularly for older patients, and the mechanisms by which the immune checkpoint inhibitor combined with chemotherapy modulates the evolution of ESCC are unknown.

METHODS

In this single-arm phase 2 trial, patients with resectable (stage II/III/IV without metastasis) ESCC were enrolled and received nanoparticle albumin-bound (nab) paclitaxel for two cycles and oral S-1 for 2 weeks, combined with intravenous toripalimab for two cycles before surgery. Combination postoperative adjuvant therapy was administered. The primary outcome was the major pathological response (MPR). Secondary outcomes included pathological complete response (pCR), overall response rate (ORR), disease control rate (DCR), disease-free survival (DFS), overall survival (OS), improvement in Stooler's dysphagia score and degree of daily living ability (dADL). Biopsies and plasma pre- and post-neoadjuvant therapy were performed using whole-exome sequencing, transcriptome sequencing, immunohistochemistry (IHC) for PD-L1, multiplex immunofluorescence (mIF) and proximity extension assay technology (PEA) for 92 proteins.

FINDINGS

From November 2019 to July 2021, 60 patients were enrolled. After neoadjuvant therapy, R0 resection was achieved in 55 (98.21%) patients. MPR was identified in 27 patients (49.09%), and 16 patients (29.09%) achieved pCR. Patients with PR, SD and PD were 37 (61.67%), 21 (35.00%) and 2 (3.33%), respectively. The overall staging, Stooler dysphagia scores and dADL were significantly decreased after treatment. 11 patients (18.3%) experienced grade ≥3 AEs. Compared to PD-L1-Low patients, PD-L1-High patients had a significantly higher ratio of PR. During therapy, the tumor mutation burden (TMB) and tumor neoantigen burden (TNB) were significantly decreased in patients with PR. Differential clonal evolution within tumors was demonstrated by analysis of intratumoral heterogeneity. Transcriptome analyses revealed that the infiltration of CD4+ T lymphocytes at baseline was associated with clinical outcome. During therapy, CD8+ T cells and CD4+ T cells were increased in all patients; however, exhausted cells, nTregs and iTregs were significantly increased in patients with non-MPR. Protein analyses revealed that the levels of IFN-γ, Gal.1 and LAMP3 can predict the clinical benefit. In addition, the expression of CD83, TNFRSF4, TNFSF14, VEGFR2, ADA, ARG1, and HO-1 was associated with serious AEs. More importantly, the integration of CD4+ T cells with plasma protein of IFN-γ, Gal.1 or LAMP3 could further distinguish responders from non-responders.

INTERPRETATION

In this study, neoadjuvant therapy with toripalimab, nab-paclitaxel and S-1 was less toxic and showed promising antitumor activity in patients with resectable ESCC. Changes in the genome, transcriptome, PD-L1 expression and serum proteins were comprehensively analyzed and correlated with clinical outcomes, which provides insight into the mechanism of action of toripalimab combined with nab-paclitaxel and S-1 in patients with ESCC.

FUNDING

This study was funded by Major projects of the ministry of science and technology of the 13th five-year plan of China [grant number: 2018ZX09201013].

Fusobacterium nucleatum Infection Induces Malignant Proliferation of Esophageal Squamous Cell Carcinoma Cell by Putrescine Production

Esophageal squamous cell carcinoma (ESCC) is a malignant upper digestive tract cancer, and its pathogenesis and etiology are poorly understood. Because gut microbes commonly impact progression, metastasis, and immunotherapy responses in colorectal cancer (CRC), the roles of the esophageal microbiota in ESCC have gradually drawn attention. As reported previously, Fusobacterium nucleatum (Fn), the notable "culprit" of CRC, can also influence the prognosis of ESCC in clinical studies. However, thus far, the underlying mechanism is unclear. In this study, 73 Chinese ESCC samples were collected. In those clinical samples, the abundance of Fn was found to be higher in tumors than in adjacent normal tissues, and a high abundance of Fn was correlated with shorter survival. Furthermore, using in vitro experiments, we demonstrated that Fn can invade ESCC cells, enhancing their proliferation capacity. The mechanism study revealed that Fn can produce high levels of putrescine after invasion, which disturbs polyamine metabolism and promotes the malignant proliferation of ESCC cells. In conclusion, Fn infection was found in Chinese ESCC tumor tissue samples and may promote ESCC progression by disturbing the polyamine metabolism pathway. IMPORTANCE Nowadays, the complex and varied interactions between microbes and human body are known to be crucial for maintaining the health of the human body. However, knowledge concerning the influence of esophageal microbes on the progression of esophageal squamous cell carcinoma is limited. Here, in our study, we confirmed that F. nucleatum can invade ESCC cells and consequently promote their proliferation, suggesting that esophageal microbes likely influence the progression of ESCC in clinical settings. Because the esophagus connects the oral cavity and stomach, acting as a canal for transporting foods, its special physical location makes it easily exposed to microorganisms. Thus, it is necessary to explore the interaction between esophageal microbes and ESCC.

Wnt signaling pathway-related gene PRICKLE1 is a prognostic biomarker for esophageal squamous cell carcinoma

Esophageal squamous cell carcinoma (ESCC) has become a major health risk to human health. Although significant clinical progress has been made in the treatment of ESCC, the prognosis of patients still needs to be improved. Therefore, it is important to screen effective molecular indicators for the prognosis of ESCC. In this study, the intersection of up-regulated genes, down-regulated genes, and Wnt signaling pathway-related genes in ESCC was taken, and 47 overlapping genes were found. PRICKLE1 was determined to be an independent prognostic factor in ESCC based on univariate and multifactorial COX risk regression models. Kaplan-Meier survival curves showed that patients in the PRICKLE1 high expression group had significantly better overall survival. In addition, we performed various experiments to examine the effects of PRICKLE1 overexpression on proliferation, migration, and apoptosis of ESCC cells. The experimental results showed that the PRICKLE1-OE group had reduced cell viability, significantly lower migration ability and significantly higher apoptosis rate compared to the NC group.Therefore, we hypothesized that high PRICKLE1 expression could be used to predict the survival rate of ESCC patients, which could be used as an independent prognostic indicator for ESCC patients and provide potential applications for ESCC clinical treatment.

Src heterodimerically activates Lyn or Fyn to serve as targets for the diagnosis and treatment of esophageal squamous cell carcinoma

Although Src is one of the oldest and most investigated oncoproteins, its function in tumor malignancy remains to be defined further. In this study, we demonstrated that the inhibition of Src activity by ponatinib effectively suppressed several malignant phenotypes of esophageal squamous cell carcinoma (ESCC) both in vitro and in vivo, whereas it did not produce growth-inhibitory effects on normal esophageal epithelial cells (NEECs). Importantly, we combined phosphoproteomics and several cellular and molecular biologic strategies to identify that Src interacted with the members of Src-family kinases (SFKs), such as Fyn or Lyn, to form heterodimers. Src interactions with Fyn and Lyn phosphorylated the tyrosine sites in SH2 (Fyn Tyr¹⁸⁵ or Lyn Tyr¹⁸³) and kinase domains (Fyn Tyr⁴²⁰ or Lyn Tyr³⁹⁷), which critically contributed to ESCC development. By contrast, Src could not form heterodimers with Fyn or Lyn in NEECs. We used RNA sequencing to comprehensively demonstrate that the inhibition of Src activity effectively blocked several critical tumor-promoting pathways, such as JAK/STAT, mTOR, stemness-related, and metabolism-related pathways. Results of the real-time polymerase chain reaction (RT-PCR) assay confirmed that Lyn and Fyn were critical effectors for the Src-mediated expression of tumor growth or metastasis-related molecules. Furthermore, results of the clinical ESCC samples showed that the hyperactivation of pSrc Tyr⁴¹⁹, Fyn Tyr¹⁸⁵ or Tyr⁴²⁰, and Lyn Tyr¹⁸³ or Tyr³⁹⁷ could be biomarkers of ESCC prognosis. This study illustrates that Src/Fyn and Src/Lyn heterodimers serve as targets for the treatment of ESCC.

Cohort size required for prognostic genes analysis of stage II/III esophageal squamous cell carcinoma

Background: Few overlaps between prognostic biomarkers are observed among different independently performed genomic studies of esophageal squamous cell carcinoma (ESCC). One of the reasons for this is the insufficient cohort size. How many cases are needed to prognostic genes analysis in ESCC? Methods: Here, based on 387 stage II/III ESCC cases analyzed by whole-genome sequencing from one single center, effects of cohort size on prognostic genes analysis were investigated. Prognostic genes analysis was performed in 100 replicates at each cohort size level using a random resampling method. Results: The number of prognostic genes followed a power-law increase with cohort size in ESCC patients with stage II and stage III, with exponents of 2.27 and 2.25, respectively. Power-law curves with increasing events number were also observed in stage II and III ESCC, respectively, and they almost overlapped. The probability of obtaining statistically significant prognostic genes shows a logistic cumulative distribution function with respect to cohort size. To achieve a 100% probability of obtaining statistically significant prognostic genes, the minimum cohort sizes required in stage II and III ESCC were approximately 95 and 60, respectively, corresponding to a number of outcome events of 33 and 36, respectively. Conclusion: In summary, the number of prognostic genes follows a power-law growth with the cohort size or events number in ESCC. The minimum events number required to achieve a 100% probability of obtaining a statistically significant prognostic gene is approximately 35.

Clinical Outcome-Related Cancer Pathways and Mutational Signatures in Patients With Unresectable Esophageal Squamous Cell Carcinoma Treated With Chemoradiotherapy

PURPOSE

Definitive chemoradiotherapy (dCRT) is a standard-of-care for locally advanced unresectable esophageal squamous cell carcinoma (ESCC). However, even in individuals treated with the same dCRT regimen, differences in the local control rate and radiation-induced thoracic toxicity exist (radiation-induced esophagitis [RIE]).

METHODS AND MATERIALS

Here, we describe a comprehensive genomic evaluation of pretreatment tumor tissue samples from 183 patients with ESCC using targeted sequencing of 474 cancer-related genes. The association between endpoints (progression-free survival [PFS], overall survival, locoregional relapse-free survival, distant metastasis-free survival), toxicity (RIE) and genomic features, including altered pathways and the mutational signature, was analyzed. An independent cohort of 84 stage II-III patients with ESCC was used for validation.

RESULTS

Gene alterations in the cell cycle pathway were identified in 87% of cases. Other frequently altered pathways included PI3K-AKT (45.9%), NOTCH (38.3%), NRF2 (36.6%), RKT-RAS (28.4%), and homologous recombination repair (HRR; 20.2%). HRR pathway alterations correlated with shortened PFS (mutation vs wild-type: 9.00 vs 14.40 months, hazard ratio, 2.10; 95% confidence interval, 1.29-3.44), while altered RTK-RAS pathways were correlated with worse overall survival in patients with ESCC treated with chemoradiotherapy (mutation vs wild-type: 23.70 vs 33.50 months; hazard ratio, 1.65; 95% confidence interval, 1.01-2.69). Furthermore, enrichment of apolipoprotein B mRNA editing enzyme, catalytic polypeptide (APOBEC) signatures (signatures 2 and 13) was identified in ESCC tumors with altered HRR pathways. High APOBEC signatures and an altered HRR pathway were correlated with poor prognoses in dCRT-treated ESCC. Moreover, the APOBEC signature and/or the presence of HRR pathway alterations were associated with poor PFS and overall survival, which was validated in an independent whole exome sequence cohort. Notably, the altered HRR pathway was also associated with high-grade RIE toxicity in patients with ESCC.

CONCLUSIONS

Collectively, our results support the use of comprehensive genomic profiling to guide treatment and minimize RIE in patients with ESCC.

The effects of altered DNA damage repair genes on mutational processes and immune cell infiltration in esophageal squamous cell carcinoma

BACKGROUND

Defects in DNA damage repair (DDR) pathways lead to genomic instability and oncogenesis. DDR deficiency is prevalent in esophageal squamous cell carcinoma (ESCC), but the effects of DDR alterations on mutational processes and tumor immune microenvironment in ECSS remain unclear.

METHODS

Whole-exome and transcriptome sequencing data of 45 ESCC samples from Taizhou, China, were used to identify genomic variations, gene expression modulation in DDR pathways, and the abundance of tumor-infiltrating immune cells. Ninety-six ESCC cases from The Cancer Genome Atlas (TCGA) project were used for validation.

RESULTS

A total of 57.8% (26/45) of the cases in the Taizhou data and 70.8% (68/96) of the cases in the TCGA data carried at least one functional impact DDR mutation. Mutations in the DDR pathways were associated with a high tumor mutation burden. Several DDR deficiency-related mutational signatures were discovered and were associated with immune cell infiltration, including T cells, monocytes, dendritic cells, and mast cells. The expression levels of two DDR genes, HFM1 and NEIL1, were downregulated in ESCC tumor tissues and had an independent effect on the infiltration of mast cells. In the Taizhou data, increased expression of HFM1 was associated with a poor prognosis, and the increased expression of NEIL1 was associated with a good outcome, but no reproducible correlation was observed in the TCGA data.

CONCLUSION

This research demonstrated that DDR alterations could impact mutational processes and immune cell infiltration in ESCC. The suppression of HFM1 and NEIL1 could play a crucial role in ESCC progression and may also serve as prognostic markers.

Comparative genomic analysis of esophageal squamous cell carcinoma among different geographic regions

Introduction

Esophageal squamous cell carcinoma (ESCC) shows remarkable variation in incidence, survival, and risk factors. Although the genomic characteristics of ESCC have been extensively characterized, the genomic differences between different geographic regions remain unclear.

Methods

In this study, we sequenced 111 patients with ESCC from northern (NC) and southern (SC) China, combined their data with those of 1081 cases from previous reports, and performed a comparative analysis among different regions. In total, 644 ESCC cases were collected from six geographic regions (NC, SC, Xinjiang, China [XJC], Japan [JP], Vietnam [VN], and Europe & America [EA]) as the discovery cohort. Validation cohort 1 included 437 patients with ESCC from the NC region. Validation cohort 2 included 54 and 57 patients from the NC and SC regions, respectively.

Results

Patients with ESCC in different regions had different genomic characteristics, including DNA signatures, tumor mutation burdens, significantly mutated genes (SMGs), altered signaling pathways, and genes associated with clinical features. Based on both the DNA mutation signature and the mutation profile of the most common genes, the NC and SC groups were clustered close together, followed by the JP, XJC, EA, and VN groups. Compared to patients with ESCC from SC, SMGs, including KMT2D, FAT1, and NOTCH1 were more frequently identified in patients with ESCC from NC. Furthermore, some genes (TDG and DNAH8) correlated with overall survival in completely opposite ways in patients with ESCC from different geographical regions.

Conclusions

Our study provides insights into genomic differences in ESCC among different regions. These differences may be related to differences in environmental carcinogens, incidence, and survival.

The High Expression of p53 Is Predictive of Poor Survival Rather TP53 Mutation in Esophageal Squamous Cell Carcinoma

TP53 is a well-known tumor suppressor gene and one of the most common genetic alterations in human cancers. However, the role of p53 as a prognostic marker of esophageal squamous cell carcinoma (ESCC) is controversial in the association between TP53 alterations and clinical outcomes. To address this issue, we evaluated TP53 mutations, p53 protein expression, clinicopathological parameters, and survivals rates in a large scale of patients with ESCC. Two cohorts were included in this study: TP53 mutations were detected by next-generation sequencing in 316 ESCC patients, and p53 protein expression was tested by immunohistochemistry in 6,028 ESCC patients. Survival analysis was performed using the Kaplan-Meier curve and the Cox proportional hazards model. TP53 mutations were found in ESCC patients from 241 of 316 (76.3%), and the rate of positive expression of p53 protein was 59.1% in 6,028 ESCC patients (including 1819 with high expression of p53 protein), respectively. Most mutations were missense, which has a high expression of p53 protein. Compared with wild-typeTP53, TP53 gene mutations were not significantly associated with survival time (p=0.083). In multivariate analysis, the p53 protein expression was an independent prognostic factor for ESCC. The high-expression group of p53 protein has poor survival (p < 0.001) compared to low-expression group in patients with ESCC. The high expression of the p53 protein, not the TP53 mutation, is predictive of poor survival in patients with ESCC, and p53 protein expression might have the potential to be a prognosis biomarker and therapy target in ESCC.

Integrated multi-omics profiling yields a clinically relevant molecular classification for esophageal squamous cell carcinoma

Integrated molecular analysis of human cancer has yielded molecular classification for precise management of cancer patients. Here, we analyzed the whole genomic, epigenomic, transcriptomic, and proteomic data of 155 esophageal squamous cell carcinomas (ESCCs). Multi-omics analysis led to the classification of ESCCs into four subtypes: cell cycle pathway activation, NRF2 oncogenic activation, immune suppression (IS), and immune modulation (IM). IS and IM cases were highly immune infiltrated but differed in the type and distribution of immune cells. IM cases showed better response to immune checkpoint blockade therapy than other subtypes in a clinical trial. We further developed a classifier with 28 features to identify the IM subtype, which predicted anti-PD-1 therapy response with 85.7% sensitivity and 90% specificity. These results emphasize the clinical value of unbiased molecular classification based on multi-omics data and have the potential to further improve the understanding and treatment of ESCC.

The Molecular Characterization of Genetic Abnormalities in Esophageal Squamous Cell Carcinoma May Foster the Development of Targeted Therapies

Esophageal cancer is among the most common tumors in the world and is associated with poor outcomes, with a 5-year survival rate of about 10-20%. Two main histological subtypes are observed: esophageal squamous cell carcinoma (ESCC), more frequent among Asian populations, and esophageal adenocarcinoma (EAC), the predominant type in Western populations. The development of molecular analysis techniques has led to the definition of the molecular alterations observed in ESCC, consistently differing from those observed in EAC. The genetic alterations observed are complex and heterogeneous and involve gene mutations, gene deletions and gene amplifications. However, despite the consistent progress in the definition of the molecular basis of ESCC, precision oncology for these patients is still virtually absent. The recent identification of molecular subtypes of ESCC with clinical relevance may foster the development of new therapeutic strategies. It is estimated that about 40% of the genetic alterations observed in ESCC are actionable. Furthermore, the recent introduction of solid tumor immunotherapy with immune checkpoint inhibitors (ICIs) showed that a minority of ESCC patients are responsive, and the administration of ICIs, in combination with standard chemotherapy, significantly improves overall survival over chemotherapy in ESCC patients with advanced disease.

High expression of caspase‐8 as a predictive factor of poor prognosis in patients with esophageal cancer

BACKGROUND

Esophageal carcinoma (ESCA) is considered to be one of the most common gastrointestinal cancers. Caspase-8 (CASP8) is a key protein of cross-talk signaling in a variety of cancers. However, the role of CASP8 expression in the prognosis of patients with ESCA has remained unexplored. Hence, it is needed to explore the clinical significance of CASP8 expression in ESCA.

METHODS

The expression and prognosis of CASP8 were investigated in ESCA using the UALCAN, GEDS, TIMER, and OncoLnc databases. The CASP8 genetic variations in ESCA were assessed using the cBioPortal database. The correlation between CASP8 expression and tumor immune invasion and immune cell surface indicators was examined using the TIMER and TISIDTISIDB datasets. Meanwhile, the abundance of the immunological cells in the tumor and healthy tissues was assessed by the CIBERSORT method. Next, information on the co-expressed genes of the differentially expressed genes (DEGs) in ESCA-tumor and ESCA-healthy tissues was obtained using the cBioPortal, UALCAN, and Coexpedia databases. Subsequently, the PPI network was constructed and the GO and KEGG pathways were analyzed using the SIRING database. Finally, CASP8 mRNA and protein expression in the ESCA tissues and matched adjacent healthy tissues were analyzed using qRT-PCR, immune-blotting, and immunohistochemistry. Additionally, the relationship between clinicopathological features and CASP8 expression was assessed.

RESULTS

ESCA tissues had higher levels of CASP8 mRNA and protein expression compared to healthy tissues. patients with an elevated level of CASP8 expression had poor overall survival (OS). CASP8 expression was significantly correlated with the degree of differentiation (P = 0.004) and lymph node metastasis (P = 0.044). There were diverse patterns of association between immunological cell surface biomarkers and CASP8 expression.

CONCLUSION

ESCA showed significant levels of CASP8 expression which may serve as a prognostic biomarker correlated to immune infiltrates in ESCA.

Role of Epidermal Growth Factor Receptor-Specific CAR-T Cells in the Suppression of Esophageal Squamous Cell Carcinoma

ESCC is a highly malignant tumor, and its morbidity and mortality in China account for more than 50% of the world's total rates. As effective treatments are lacking, the 5-year survival rate of patients does not exceed 30%. CAR-T-cell-based immunotherapy has emerged as one of the most promising cancer treatments; however, there are relatively fewer reports regarding its application for ESCC. In this study, we conducted large-sample whole-genome sequencing (WGS) and RNA-seq analysis of patients with ESCC from China to examine the feasibility of EGFR-targeting CAR-T cells in the treatment of ESCC. We found much higher levels of EGFR gene amplification and overexpression in tumors than in the normal tissues, indicating that EGFR could be a promising target of CAR-T-cell-based immunotherapy in ESCC. Therefore, we tested EGFR-targeting CAR-T cells for lytic activity against ESCC cells as a model to establish cellular immunotherapy for ESCC. Five types of CAR-T cells targeting EGFR were constructed, two of which, CAR1-T and CAR2-T, showed a strong cytotoxicity against ESCC in in vitro and in vivo experiments. The results of this study suggest that CAR1-T and CAR2-T have the potential to be used for anti-ESCC immunotherapy in clinics.

Detection of somatic copy number deletion of the CDKN2A gene by quantitative multiplex PCR for clinical practice

Background

A feasible method to detect somatic copy number deletion (SCND) of genes is still absent to date.

Methods

Interstitial base-resolution deletion/fusion coordinates for CDKN2A were extracted from published articles and our whole genome sequencing (WGS) datasets. The copy number of the CDKN2A gene was measured with a quantitative multiplex PCR assay P16-Light and confirmed with whole genome sequencing (WGS).

Results

Estimated common deletion regions (CDRs) were observed in many tumor suppressor genes, such as ATM, CDKN2A, FAT1, miR31HG, PTEN, and RB1, in the SNP array-based COSMIC datasets. A 5.1 kb base-resolution CDR could be identified in &gt;90% of cancer samples with CDKN2A deletion by sequencing. The CDKN2A CDR covers exon-2, which is essential for P16INK4A and P14ARF synthesis. Using the true CDKN2A CDR as a PCR target, a quantitative multiplex PCR assay P16-Light was programmed to detect CDKN2A gene copy number. P16-Light was further confirmed with WGS as the gold standard among cancer tissue samples from 139 patients.

Conclusion

The 5.1 kb CDKN2A CDR was found in &gt;90% of cancers containing CDKN2A deletion. The CDKN2A CDR was used as a potential target for developing the P16-Light assay to detect CDKN2A SCND and amplification for routine clinical practices.

A more novel and robust gene signature predicts outcome in patients with esophageal squamous cell carcinoma

BACKGROUND

Esophageal squamous cell carcinoma (ESCC) is a life-threatening thoracic tumor with a poor prognosis. The tumor microenvironment (TME) mainly comprises tumor cells and tumor-infiltrating immune cells mixed with stromal components. The latest research has displayed that tumor immune cell infiltration (ICI) is closely connected with the ESCC patients' clinical prognosis. This study was designed to construct a gene signature based on the ICI of ESCC to predict prognosis.

METHODS

Based on the selection criteria we set, the eligible ESCC cases from the GSE53625 and TCGA-ESCA datasets were chosen for the training cohort and the validation cohort, respectively. Unsupervised clustering detailed grouped ESCC cases of the training cohort based on the ICI profile. We determined the differential expression genes (DEGs) between the ICI clusters, and, subsequently, we adopted the univariate Cox analysis to recognize DEGs with prognostic potential. These screened DEGs underwent a Lasso regression, which then generated a gene signature. The harvested signature's predictive ability was further examined by the Kaplan-Meier analysis, Cox analysis, ROC, IAUC, and IBS. More importantly, we listed similar studies in the most recent year and compared theirs with ours. We performed the functional annotation, immune relevant signature correlation analysis, and immune infiltrating analysis to thoroughly understand the functional mechanism of the signature and the immune cells' roles in the gene signature's predicting capacity.

RESULTS

A sixteen-gene signature (ARSD, BCAT1, BIK, CLDN11, DLEU7-AS1, GGH, IGFBP2, LINC01037, LINC01446, LINC01497, M1AP, PCSK2, PCSK5, PPP2R2A, TIGD7, and TMSB4X) was generated from the Lasso model. We then confirmed the signature as having solid and stable prognostic capacity by several statistical methods. We revealed the superiority of our signature after comparing it to our predecessors, and the GSEA uncovered the specifically mechanism of action related to the gene signature. Two immune relevant signatures, including GZMA and LAG3 were identified associating with our signature. The immune-infiltrating analysis identified crucial roles of resting mast cells, which potentially support the sixteen-gene signature's prognosis ability.

CONCLUSIONS

We discovered a robust sixteen-gene signature that can accurately predict ESCC prognosis. The immune relevant signatures, GZMA and LAG3, and resting mast cells infiltrating were closely linked to the sixteen-gene signature's ability.

Molecular subtyping of esophageal squamous cell carcinoma by large-scale transcriptional profiling: Characterization, therapeutic targets, and prognostic value

The tumor heterogeneity of the transcriptional profiles is independent of genetic variation. Several studies have successfully identified esophageal squamous cell carcinoma (ESCC) subtypes based on the somatic mutation profile and copy number variations on the genome. However, transcriptome-based classification is limited. In this study, we classified 141 patients with ESCC into three subtypes (Subtype 1, Subtype 2, and Subtype 3) via tumor sample gene expression profiling. Differential gene expression (DGE) analysis of paired tumor and normal samples for each subtype revealed significant difference among subtypes. Moreover, the degree of change in the expression levels of most genes gradually increased from Subtype 1 to Subtype 3. Gene set enrichment analysis (GSEA) identified the representative pathways in each subtype: Subtype 1, abnormal Wnt signaling pathway activation; Subtype 2, inhibition of glycogen metabolism; and Subtype 3, downregulation of neutrophil degranulation process. Weighted gene co-expression network analysis (WGCNA) was used to elucidate the finer regulation of biological pathways and discover hub genes. Subsequently, nine hub genes (CORO1A, CD180, SASH3, CD52, CD300A, CD14, DUSP1, KIF14, and MCM2) were validated to be associated with survival in ESCC based on the RNA sequencing (RNA-seq) data from The Cancer Genome Atlas (TCGA) database. The clustering analysis of ESCC granted better understanding of the molecular characteristics of ESCC and led to the discover of new potential therapeutic targets that may contribute to the clinical treatment of ESCC.

PD0166285 sensitizes esophageal squamous cell carcinoma to radiotherapy by dual inhibition of WEE1 and PKMYT1

Background

Esophageal squamous cell carcinoma (ESCC) is an aggressive tumor with a 5-year survival rate of only 20%. More than 80% of ESCC patients possess TP53 mutation, which abolishes the G1/S checkpoint and accelerates the cell cycle. Thus, WEE1 and PKMYT1, regulators of G2/M phase in cell cycle, play essential roles in TP53-mutated cancer cells. PD0166285(PD) is a pyridopyrimidine compound that can inhibit WEE1 and PKMYT1 simultaneously, however, the effects of PD on ESCC, either as monotherapy or in combination therapy with radiotherapy, remain unclear.

Methods

To measure the anti-tumor efficacy of PD in ESCC cells, cell viability, cell cycle and cell apoptosis assays were examined in KYSE150 and TE1 cells with PD treatment. The combination therapy of PD and irradiation was also performed in ESCC cells to find whether PD can sensitize ESCC cells to irradiation. Vivo assays were also performed to investigate the efficacy of PD.

Results

We found that the IC50 values of PD among ESCC cells ranged from 234 to 694 nM, PD can regulate cell cycle and induce cell apoptosis in ESCC cells in a dose-dependent manner. When combined with irradiation, PD sensitized ESCC cells to irradiation by abolishing G2/M phase arrest, inducing a high ratio of mitosis catastrophe, eventually leading to cell death. We also demonstrated that PD can attenuate DNA damage repair by inhibiting Rad51, further research also found the interaction of WEE1 and Rad51. In vivo assays, PD inhibited the tumor growth in mice, combination therapy showed better therapeutic efficacy.

Conclusion

PD0166285 can exert antitumor effect by inhibiting the function of WEE1 and PKMYT1 in ESCC cells, and also sensitize ESCC cells to irradiation not only by abolishing G2/M arrest but also attenuating DNA repair directly. We believe PD0166285 can be a potent treatment option for ESCC in the future.

Caspase-8 mutants activate Nrf2 via phosphorylating SQSTM1 to protect against oxidative stress in esophageal squamous cell carcinoma

Caspase-8, a caspase protein, is involved in the regulation of multiple cell death modes and has a predominant role in cell death. Cancer-associated mutations in the protein-coding region of caspase-8 have been widely reported in several solid tumors and might lead to the loss of its apoptotic function and contribute to the pathogenesis of tumors. However, the specific function and molecular mechanisms of mutant caspase-8 in the development of esophageal squamous cell carcinoma (ESCC) remain unknown. Here, we identified caspase-8 mutants exert tumor-promoting properties in ESCC, patients with the mutants presented a worse prognosis, and caspase-8 mutants lost the suppressive effect on tumor growth in ESCC cells. In addition, we demonstrated that caspase-8 mutants gain a new function of abolishing excess reactive oxygen species (ROS) to maintain ESCC cell growth under oxidative stress. An Nrf2 inhibitor reduced the effects of caspase-8 mutants against oxidative stress. Caspase-8 mutants combined with mTOR to phosphorylate SQSTM1 at Ser349, facilitating the interaction of SQSTM1 and Keap1 and reducing the degradation of the Nrf2 protein. Therefore, our study demonstrated that caspase-8 mutants gain a new function of protecting against oxidative stress via the mTOR/SQSTM1/Keap1/Nrf2 axis in ESCC. Caspase-8 status may be a new prognostic factor for survival in ESCC patients.

Characterization of somatic structural variations in 528 Chinese individuals with Esophageal squamous cell carcinoma

Esophageal squamous cell carcinoma (ESCC) demonstrates high genome instability. Here, we analyze 528 whole genomes to investigate structural variations' mechanisms and biological functions. SVs show multi-mode distributions in size, indicating distinct mutational processes. We develop a tool and define five types of complex rearrangements with templated insertions. We highlight a type of fold-back inversion, which is associated with poor outcomes. Distinct rearrangement signatures demonstrate variable genomic metrics such as replicating time, spatial proximity, and chromatin accessibility. Specifically, fold-back inversion tends to occur near the centrosome; TD-c2 (Tandem duplication-cluster2) is significantly enriched in chromatin-accessibility and early-replication region compared to other signatures. Analyses of TD-c2 signature reveal 9 TD hotspots, of which we identify a hotspot consisting of a super-enhancer of PTHLH. We confirm the oncogenic effect of the PTHLH gene and its interaction with enhancers through functional experiments. Finally, extrachromosomal circular DNAs (ecDNAs) are present in 14% of ESCCs and have strong selective advantages to driver genes.

Aristolochic acid-associated cancers: a public health risk in need of global action

Aristolochic acids (AAs) are a group of naturally occurring compounds present in many plant species of the Aristolochiaceae family. Exposure to AA is a significant risk factor for severe nephropathy, and urological and hepatobiliary cancers (among others) that are often recurrent and characterized by the prominent mutational fingerprint of AA. However, herbal medicinal products that contain AA continue to be manufactured and marketed worldwide with inadequate regulation, and possible environmental exposure routes receive little attention. As the trade of food and dietary supplements becomes increasingly globalized, we propose that further inaction on curtailing AA exposure will have far-reaching negative effects on the disease trends of AA-associated cancers. Our Review aims to systematically present the historical and current evidence for the mutagenicity and carcinogenicity of AA, and the effect of removing sources of AA exposure on cancer incidence trends. We discuss the persisting challenges of assessing the scale of AA-related carcinogenicity, and the obstacles that must be overcome in curbing AA exposure and preventing associated cancers. Overall, this Review aims to strengthen the case for the implementation of prevention measures against AA's multifaceted, detrimental and potentially fully preventable effects on human cancer development.

Oxidative stress genes in patients with esophageal squamous cell carcinoma: construction of a novel prognostic signature and characterization of tumor microenvironment infiltration

Background

Oxidative stress plays an important role in the progression of various types of tumors. However, its role in esophageal squamous cell carcinoma (ESCC) has seldom been explored. This study aimed to discover prognostic markers associated with oxidative stress in ESCC to improve the prediction of prognosis and help in the selection of effective immunotherapy for patients.

Results

A consensus cluster was constructed using 14 prognostic differentially expressed oxidative stress-related genes (DEOSGs) that were remarkably related to the prognosis of patients with ESCC. The infiltration levels of neutrophils, plasma cells, and activated mast cells, along with immune score, stromal score, and estimated score, were higher in cluster 1 than in cluster 2. A prognostic signature based on 10 prognostic DEOSGs was devised that could evaluate the prognosis of patients with ESCC. Calculated risk score proved to be an independent clinical prognostic factor in the training, testing, and entire sets. P53 signaling pathway was highly enriched in the high-risk group. The calculated risk score was positively related to the infiltration levels of resting mast cells, memory B cells, and activated natural killer (NK) cells and negatively associated with the infiltration levels of M1 and M2 macrophages. The relationship between clinical characteristics and risk score has not been certified. The half-maximal inhibitory concentration (IC50) values for sorafenib and gefitinib were lower for patients in the low-risk group.

Conclusion

Our prognostic signature based on 10 prognostic DEOSGs could predict the disease outcomes of patients with ESCC and had strong clinical value. Our study improves the understanding of oxidative stress in tumor immune microenvironment (TIME) and provides insights for developing improved and efficient immunotherapy strategies.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12859-022-04956-9.

DETexT: An SNV detection enhancement for low read depth by integrating mutational signatures into TextCNN

Detecting SNV at very low read depths helps to reduce sequencing requirements, lowers sequencing costs, and aids in the early screening, diagnosis, and treatment of cancer. However, the accuracy of SNV detection is significantly reduced at read depths below ×34 due to the lack of a sufficient number of read pairs to help filter out false positives. Many recent studies have revealed the potential of mutational signature (MS) in detecting true SNV, understanding the mutational processes that lead to the development of human cancers, and analyzing the endogenous and exogenous causes. Here, we present DETexT, an SNV detection method better suited to low read depths, which classifies false positive variants by combining MS with deep learning algorithms to mine correlation information around bases in individual reads without relying on the support of duplicate read pairs. We have validated the effectiveness of DETexT on simulated and real datasets and conducted comparative experiments. The source code has been uploaded to https://github.com/TrinaZ/extra-lowRD for academic use only.

The KEAP1-NRF2 System and Esophageal Cancer

NRF2 (nuclear factor erythroid 2-related factor 2) is a transcription factor that regulates the expression of many cytoprotective genes. NRF2 activation is mainly regulated by KEAP1 (kelch-like ECH-associated protein 1) through ubiquitination and proteasome degradation. Esophageal cancer is classified histologically into two major types: esophageal squamous cell carcinoma (ESCC) and esophageal adenocarcinoma (EAC). ESCC harbors more genetic alterations in the KEAP-NRF2 system than EAC does, which results in NRF2 activation in these cancers. NRF2-addicted ESCC exhibits increased malignancy and acquisition of resistance to chemoradiotherapy. Therefore, it has been recognized that the development of drugs targeting the KEAP1-NRF2 system based on the molecular dissection of NRF2 function is important and urgent for the treatment of ESCC, along with efficient clinical screening for NRF2-addicted ESCC patients. Recently, the fate of NRF2-activated cells in esophageal tissues, which was under the influence of strong cell competition, and its relationship to the pathogenesis of ESCC, was clarified. In this review, we will summarize the current knowledge of the KEAP1-NRF2 system and the treatment of ESCC. We propose three main strategies for the treatment of NRF2-addicted cancer: (1) NRF2 inhibitors, (2) synthetic lethal drugs for NRF2-addicted cancers, and (3) NRF2 inducers of the host defense system.

Identification of key somatic oncogenic mutation based on a confounder-free causal inference model

Abnormal cell proliferation and epithelial-mesenchymal transition (EMT) are the essential events that induce cancer initiation and progression. A fundamental goal in cancer research is to develop an efficient method to detect mutational genes capable of driving cancer. Although several computational methods have been proposed to identify these key mutations, many of them focus on the association between genetic mutations and functional changes in relevant biological processes, but not their real causality. Causal effect inference provides a way to estimate the real induce effect of a certain mutation on vital biological processes of cancer initiation and progression, through addressing the confounder bias due to neutral mutations and unobserved latent variables. In this study, integrating genomic and transcriptomic data, we construct a novel causal inference model based on a deep variational autoencoder to identify key oncogenic somatic mutations. Applied to 10 cancer types, our method quantifies the causal effect of genetic mutations on cell proliferation and EMT by reducing both observed and unobserved confounding biases. The experimental results indicate that genes with higher mutation frequency do not necessarily mean they are more potent in inducing cancer and promoting cancer development. Moreover, our study fills a gap in the use of machine learning for causal inference to identify oncogenic mutations.

Identifying key mutations of cancers is helpful to better understand the mechanisms of cancer cell transformation and is critical for therapeutic approaches. Besides sequence and structure-based computational approaches, some functional impact-based methods which consider the association between mutation events and the activity of cancer-related biological processes have also been developed to detect key mutations. However, these methods mainly consider the correlation but ignore that the correlation is far from causality due to the existence of observed and unobserved confounding factors. We develop a confounder-free machine learning-based causal inference framework to estimate the causal effect of mutations on abnormal cell proliferation and epithelial-mesenchymal transition (EMT). It fills a gap in the use of causal mechanisms to discover potential driver mutations in cancer biological systems. Applying our method to 10 cancer types, the identified key mutations are highly consistent with public well-verified ones. Additionally, some new key mutations have also been discovered.

Untargeted serum metabolomics reveals potential biomarkers and metabolic pathways associated with esophageal cancer

Metabolomics has been reported as an efficient tool to screen biomarkers that are related to esophageal cancer. However, the metabolic biomarkers identifying malignant degrees and therapeutic efficacy are still largely unknown in the disease. Here, GC-MS-based metabolomics was used to understand metabolic alteration in 137 serum specimens from patients with esophageal cancer, which is approximately two- to fivefold as many plasma specimens as the previous reports. The elevated amino acid metabolism is in sharp contrast to the reduced carbohydrate as a characteristic feature of esophageal cancer. Comparative metabolomics showed that most metabolic differences were determined between the early stage (0–II) and the late stage (III and IV) among the 0–IV stages of esophageal cancer and between patients who received treatment and those who did not receive treatment. Glycine, serine, and threonine metabolism and glycine were identified as the potentially overlapped metabolic pathway and metabolite, respectively, in both disease progress and treatment effect. Glycine, fructose, ornithine, and threonine can be a potential array for the evaluation of disease prognosis and therapy in esophageal cancer. These results highlight the means of identifying previously unknown biomarkers related to esophageal cancer by a metabolomics approach.

Integrated cohort of esophageal squamous cell cancer reveals genomic features underlying clinical characteristics

Esophageal squamous cell cancer (ESCC) is the major pathologic type of esophageal cancer in Asian population. To systematically evaluate the mutational features underlying clinical characteristics, we establish the integrated dataset of ESCC-META that consists of 1930 ESCC genomes from 33 datasets. The data process pipelines lead to well homogeneity of this integrated cohort for further analysis. We identified 11 mutational signatures in ESCC, some of which are related to clinical features, and firstly detect the significant mutated hotspots in TGFBR2 and IRF2BPL. We screen the survival related mutational features and found some genes had different prognostic impacts between early and late stage, such as PIK3CA and NFE2L2. Based on the results, an applicable approach of mutational score is proposed and validated to predict prognosis in ESCC. As an open-sourced, quality-controlled and updating mutational landscape, the ESCC-META dataset could facilitate further genomic and translational study in this field.

Inactivation of Hippo pathway characterizes a poor-prognosis subtype of esophageal cancer

Identification of molecular subtypes that reflect different prognoses and treatment responses, especially immune checkpoint inhibitors (ICIs) in esophageal squamous cell carcinoma (ESCC), is essential for treatment decisions. We performed targeted sequencing in 201 patients with ESCC to discover genetic subtypes and validate our findings via multiple data sets. We identified 3 driver genes (FCGBP, GRIN2B, and FRY), and recurrent truncating mutations in FRY impaired its tumor-suppressive function and promoted tumor proliferation. A 3-gene mutation signature (FAT1, FAT3, and FRY) recognized a molecular subtype named “FAT/FRY” with frequent Hippo pathway–related mutations. In multiple ESCC cohorts, the patients with the FAT/FRY subtype had poorer prognosis than did patients in the WT group. Transcriptome analysis indicated that the FAT/FRY subtype was characterized by inactivation of the Hippo pathway, hypoxia, chemoresistance, higher infiltration of CD8⁺ T cells and activated DCs, and a transcriptome similar to that of cancer responders. Furthermore, the 3-gene signature predicted better survival for patients treated with ICIs, partially explained by its positive correlation with the tumor mutation burden and neoantigen burden. The 3-gene signature is a biomarker to recognize the FAT/FRY molecular subtype, evaluate prognosis, and select potential beneficiaries of ICIs in ESCC.

Targeting Aberrant Histone Posttranscription Modification Machinery in Esophageal Squamous Cell Carcinoma: Current Findings and Challenges

Esophageal squamous cell carcinoma (ESCC) is an aggressive malignancy, but the survival rates of patients with ESCC have not improved as yet largely because the available targeted therapies are limited. Histone posttranscription modification (PTM) is a critical epigenetic regulation. Several deregulations in histone PTM machinery have been identified to promote malignant phenotypes of ESCC, providing druggable targets in treating ESCC. Hereby, we briefly describe current progress and challenges ahead in this field.

LHX2 Enhances the Malignant Phenotype of Esophageal Squamous Cell Carcinoma by Upregulating the Expression of SERPINE2

LHX2 dysregulations have been found to present in cancers, but the function of LHX2 in esophageal squamous cell carcinoma (ESCC) remains unknown. Here, we report that LHX2 was upregulated in ESCC tissues in comparison to the LHX2 levels in adjacent normal tissues. Loss- and gain-of-function experiments demonstrated that the knockdown of LHX2 markedly inhibited ESCC cells’ proliferation, migration, invasion, tumor growth and metastasis, whereas the overexpression of LHX2 had the opposite effects. A mechanistic investigation revealed that LHX2 bound to the promoter of SERPINE2 gene and transcriptionally regulated the expression of SERPINE2. Collectively, LHX2 facilitates ESCC tumor progression, and it could be a potential therapeutic target for ESCC.

N-linked glycoproteomic profiling in esophageal squamous cell carcinoma

BACKGROUND

Mass spectrometry-based proteomics and glycomics reveal post-translational modifications providing significant biological insights beyond the scope of genomic sequencing.

AIM

To characterize the N-linked glycoproteomic profile in esophageal squamous cell carcinoma (ESCC) via two complementary approaches.

METHODS

Using tandem multilectin affinity chromatography for enrichment of N-linked glycoproteins, we performed N-linked glycoproteomic profiling in ESCC tissues by two-dimensional gel electrophoresis (2-DE)-based and isobaric tags for relative and absolute quantification (iTRAQ) labeling-based mass spectrometry quantitation in parallel, followed by validation of candidate glycoprotein biomarkers by Western blot.

RESULTS

2-DE-based and iTRAQ labeling-based quantitation identified 24 and 402 differentially expressed N-linked glycoproteins, respectively, with 15 in common, demonstrating the outperformance of iTRAQ labeling-based quantitation over 2-DE and complementarity of these two approaches. Proteomaps showed the distinct compositions of functional categories between proteins and glycoproteins with differential expression associated with ESCC. Western blot analysis validated the up-regulation of total procathepsin D and high-mannose procathepsin D, and the down-regulation of total haptoglobin, high-mannose clusterin, and GlcNAc/sialic acid-containing fraction of 14-3-3ζ in ESCC tissues. The serum levels of glycosylated fractions of clusterin, proline-arginine-rich end leucine-rich repeat protein, and haptoglobin in patients with ESCC were remarkably higher than those in healthy controls.

CONCLUSION

Our study provides insights into the aberrant N-linked glycoproteome associated with ESCC, which will be a valuable resource for future investigations.

FAM135B sustains the reservoir of Tip60-ATM assembly to promote DNA damage response

BACKGROUND

Recently, the mechanism by which cells adapt to intrinsic and extrinsic stresses has received considerable attention. Tat-interactive protein 60-kDa/ataxia-telangiectasia-mutated (TIP60/ATM) axis-mediated DNA damage response (DDR) is vital for maintaining genomic integrity.

METHODS

Protein levels were detected by western blot, protein colocalisation was examined by immunofluorescence (IF) and protein interactions were measured by co-immunoprecipitation, proximity ligation assay and GST pull-down assays. Flow cytometry, comet assay and IF assays were used to explore the biological functions of sequence similarity 135 family member B (FAM135B) in DDR. Xenograft tumour, FAM135B transgenic mouse models and immunohistochemistry were utilised to confirm in vitro observations.

RESULTS

We identified a novel DDR regulator FAM135B which could protect cancer cells from genotoxic stress in vitro and in vivo. The overexpression of FAM135B promoted the removal of γH2AX and 53BP1 foci, whereas the elimination of FAM135B attenuated these effects. Consistently, our findings revealed that FAM135B could promote homologous recombination and non-homologous end-joining repairs. Further study demonstrated that FAM135B physically bound to the chromodomain of TIP60 and improved its histone acetyltransferase activity. Moreover, FAM135B enhanced the interactions between TIP60 and ATM under resting conditions. Intriguingly, the protein levels of FAM135B dramatically decreased following DNA damage stress but gradually increased during the DNA repair period. Thus, we proposed a potential DDR mechanism where FAM135B sustains a reservoir of pre-existing TIP60-ATM assemblies under resting conditions. Once cancer cells suffer DNA damage, FAM135B is released from TIP60, and the functioning pre-assembled TIP60-ATM complex participates in DDR.

CONCLUSIONS

We characterised FAM135B as a novel DDR regulator and further elucidated the role of the TIP60-ATM axis in response to DNA damage, which suggests that targeting FAM135B in combination with radiation therapy or chemotherapy could be a potentially effective approach for cancer treatment.

C12orf59 Promotes Esophageal Squamous Cell Carcinoma Progression via YAP-Mediated Epithelial-Mesenchymal Transition

C12orf59 is a novel gene widely expressed in diverse normal human tissues. Aberrant expression of C12orf59, which is involved in tumor progression, has been reported in a few types of cancer. However, its expression and biological function in esophageal squamous cell carcinoma (ESCC) remain largely unclear. Here, we found that the mRNA and protein levels of C12orf59 were prominently higher in both tumor tissues and most ESCC cell lines. Functionally, C12orf59 overexpression promoted ESCC cell proliferation, migration and invasion, whereas C12orf59 depletion worked oppositely. Mechanistically, C12orf59 exerted its oncogenic function through the induction of epithelial-mesenchymal transition (EMT) of ESCC cells, which relied on Yes-associated protein (YAP) dephosphorylation and nuclear translocation. Constitutively active YAP further facilitated cell migration, invasion and EMT induced by enforced C12orf59 overexpression. On the contrary, increased cell motility and EMT caused by enforced C12orf59 overexpression were dramatically repressed upon YAP inactivation by verteporfin. Thus, we conclude that YAP activation driven by C12orf59 contributes to the malignancy of ESCC through EMT and that targeting drugs for C12orf59 combined with YAP inhibitor may be a potential therapeutic strategy for ESCC.

High expression of nuclear NRF2 combined with NFE2L2 alterations predicts poor prognosis in esophageal squamous cell carcinoma patients

Nuclear factor erythroid-2 related factor-2 (NFE2L2 or NRF2) is a frequently mutated gene in esophageal squamous cell carcinoma (ESCC). However, the roles of NFE2L2 alterations in ESCC remain elusive. In order to elucidate this issue, 130 ESCC patients who underwent esophagectomy were enrolled. The majority of tumor tissues were positive for NRF2, which was significantly enriched in the nucleus of the primary tumor tissues compared with the noncancerous mucosae. Primary ESCC tumors positive for NRF2 tended to be positive for NAD(P)H quinone oxidoreductase 1 (NQO1) as the downstream target of NRF2. There was a positive correlation between NRF2 and NQO1 expression level in primary tumors. NQO1 staining in primary tumors with NRF2 nuclear expression was significantly stronger than that with NRF2 cytoplasmic expression. In addition, high concordance for the status of NRF2 expression between primary tumors and corresponding metastatic lesions was observed. Next, we found high expression of nuclear NRF2 (the proportion of nuclear NRF2 expression >20% or nuclear NRF2 immunohistochemistry score >20) predicted shorter overall survival in patients with dual-positive expression of NRF2 and NQO1. Captured-based targeted sequencing revealed that NFE2L2 somatic alterations were observed in 52.8% of ESCC patients with dual-positive expression of NRF2 and NQO1. NFE2L2 amplification and mutations within the DLG/ETGE motifs were seen more frequently in ESCC tumors with nuclear or nucleocytoplasmic expression of NRF2 compared with those with cytoplasmic expression of NRF2. We also found high expression of nuclear NRF2 plus the status of NFE2L2 alteration exhibited high performance in predicting prognosis of ESCC patients. Our study demonstrated that high nuclear NRF2 expression and NFE2L2 alterations were associated with poor prognosis of ESCC patients. These findings suggest that NRF2 signaling pathway might play vital roles in ESCC malignancy and the aberrant activation of NRF2 pathway predicts unfavorable prognosis in ESCC.

Immune Infiltration Represents Potential Diagnostic and Prognostic Biomarkers for Esophageal Squamous Cell Carcinoma

Background

Immune infiltrates in the tumor microenvironment have established roles in tumor growth, invasion, and metastasis. However, the diagnostic and prognostic potential of immune cell signature in esophageal squamous cell carcinoma (ESCC) remains unclear.

Results

The proportions of 22 subsets of immune cells from 331 samples including 205 ESCC and 126 normal esophageal mucosa retrieved from TCGA, GEO, and GTEx databases were deciphered by CIBERSORT. Nine overlapping subsets of immune cells were identified as important features for discrimination of ESCC from normal tissue in the training cohort by LASSO and Boruta algorithms. A diagnostic immune score (DIS) developed by XGBoost showed high specificities and sensitivities in the training cohort, the internal validation cohort, and the external validation cohort (AUC: 0.999, 0.813, and 0.966, respectively). Furthermore, the prognostic immune score (PIS) was developed based on naive B cells and plasma cells using Cox proportional hazards model. The PIS, an independent prognostic predictor, classified patients with ESCC into low- and high-risk subgroups in the internal validation cohort (P = 0.038) and the external validation cohort (P = 0.022). In addition, a nomogram model comprising age, N stage, TNM stage, and PIS was constructed and performed excellent (HR = 4.17, 95% CI: 2.22-7.69, P < 0.0001) in all ESCC patients, with a time-dependent 5-year AUC of 0.745 (95% CI: 0.644 to 0.845), compared with PIS or TNM stage as a prognostic model alone.

Conclusion

Our DIS, PIS, and nomogram models based on infiltrated immune features may aid diagnosis and survival prediction for patients with ESCC.

Characterization of the Intra-tumoral B Cell Immunoglobulin Repertoire Is of Prognostic Value for Esophageal Squamous Cell Carcinoma

Esophageal Squamous Cell carcinomas (ESCC) is a highly heterogeneous malignancy that is among the leading cause of cancer-related death worldwide. B cells play pivotal roles in the immune defense system and cancer progression and regression, yet the repertoire of tumor infiltrating B cells (TIBs) and its association with clinical outcome remains unexplored in ESCC. Here we collected bulk RNA-seq sequencing data from 119 ESCC tumors and matched adjacent normal samples to delineate the B cell repertoire. We found that ESCC is more heavily infiltrated by B cells and plasma cells compared to activated T cells. The immunoglobulin heavy chain variable region (IGHV) gene usage was remarkably biased and IGHV3-74 was under-represented in ESCC tumors. The TIBs showed a more oligoclonal profile along with widespread clonal expansion and IgG subclass switch events (CSRs). Survival analysis revealed several unexpected associations between tumor infiltrating B cells and prognosis. Higher levels of immunoglobulin expression (IGH), CD138 expression, IGH to MS4A1 ratio, CSR events and clone diversity are all associated with better survival. Notably, we found that the abundance of CD20-negative IgG2-producing plasma cells has a strong positive effect on overall survival with a hazard ratio (HR) of 0.40 (log-rank p: 0.002). Combing molecular subtyping, the IgG2-producing plasma cells could stratify high-risk patients more accurately with a HR of 0.253 (log-rank p: 0.0006). The direct link between protective B cell populations and ESCC prognosis provides biomarkers for high-risk patient selection and holds great promise for developing strategies for immunotherapy targeting B cells in ESCC patients.

A Pan-Cancer Analysis Revealing the Dual Roles of Lysine (K)-Specific Demethylase 6B in Tumorigenesis and Immunity

Introduction: Epigenetic-targeted therapy has been increasingly applied in the treatment of cancers. Lysine (K)-specific demethylase 6B (KDM6B) is an epigenetic enzyme involved in the coordinated control between cellular intrinsic regulators and the tissue microenvironment whereas the pan-cancer analysis of KDM6B remains unavailable.

Methods: The dual role of KDM6B in 33 cancers was investigated based on the GEO (Gene Expression Omnibus) and TCGA (The Cancer Genome Atlas) databases. TIMER2 and GEPIA2 were applied to investigate the KDM6B levels in different subtypes or stages of tumors. Besides, the Human Protein Atlas database allowed us to conduct a pan-cancer study of the KDM6B protein levels. GEPIA2 and Kaplan–Meier plotter were used for the prognosis analysis in different cancers. Characterization of genetic modifications of the KDM6B gene was analyzed by the cBioPortal. DNA methylation levels of different KDM6B probes in different TCGA tumors were analyzed by MEXPRESS. TIMER2 was applied to determine the association of the KDM6B expression and immune infiltration and DNA methyltransferases. Spearman correlation analysis was used to assess the association of the KDM6B expression with TMB (tumor mutation burden) and MSI (microsatellite instability). The KEGG (Kyoto encyclopedia of genes and genomes) pathway analysis and GO (Gene ontology) enrichment analysis were used to further investigate the potential mechanism of KDM6B in tumor pathophysiology.

Results: KDM6B was downregulated in 11 cancer types and upregulated across five types. In KIRC (kidney renal clear cell carcinoma) and OV (ovarian serous cystadenocarcinoma), the KDM6B level was significantly associated with the pathological stage. A high level of KDM6B was related to poor OS (overall survival) outcomes for THCA (thyroid carcinoma), while a low level was correlated with poor OS and DFS (disease-free survival) prognosis of KIRC. The KDM6B expression level was associated with TMB, MSI, and immune cell infiltration, particularly cancer-associated fibroblasts, across various cancer types with different correlations. Furthermore, the enrichment analysis revealed the relationship between H3K4 and H3K27 methylation and KDM6B function.

Conclusion: Dysregulation of the DNA methyltransferase activity and methylation levels of H3K4 and H3K27 may involve in the dual role of KDM6B in tumorigenesis and development. Our study offered a relatively comprehensive understanding of KDM6B’s dual role in cancer development and response to immunotherapy.

Current and Future Perspectives of Cell-Free DNA in Liquid Biopsy

A liquid biopsy is a minimally invasive or non-invasive method to analyze a range of tumor material in blood or other body fluids, including circulating tumor cells (CTCs), cell-free DNA (cfDNA), messenger RNA (mRNA), microRNA (miRNA), and exosomes, which is a very promising technology. Among these cancer biomarkers, plasma cfDNA is the most widely used in clinical practice. Compared with a tissue biopsy of traditional cancer diagnosis, in assessing tumor heterogeneity, a liquid biopsy is more reliable because all tumor sites release cfDNA into the blood. Therefore, a cfDNA liquid biopsy is less invasive and comprehensive. Moreover, the development of next-generation sequencing technology makes cfDNA sequencing more sensitive than a tissue biopsy, with higher clinical applicability and wider application. In this publication, we aim to review the latest perspectives of cfDNA liquid biopsy clinical significance and application in cancer diagnosis, treatment, and prognosis. We introduce the sequencing techniques and challenges of cfDNA detection, analysis, and clinical applications, and discuss future research directions.

Comprehensive characterization of posttranscriptional impairment-related 3'-UTR mutations in 2413 whole genomes of cancer patients

The 3' untranslated region (3'-UTR) is the vital element regulating gene expression, but most studies have focused on variations in RNA-binding proteins (RBPs), miRNAs, alternative polyadenylation (APA) and RNA modifications. To explore the posttranscriptional function of 3'-UTR somatic mutations in tumorigenesis, we collected whole-genome data from 2413 patients across 18 cancer types. Our updated algorithm, PIVar, revealed 25,216 3'-UTR posttranscriptional impairment-related SNVs (3'-UTR piSNVs) spanning 2930 genes; 24 related RBPs were significantly enriched. The somatic 3'-UTR piSNV ratio was markedly increased across all 18 cancer types, which was associated with worse survival for four cancer types. Several cancer-related genes appeared to facilitate tumorigenesis at the protein and posttranscriptional regulation levels, whereas some 3'-UTR piSNV-affected genes functioned mainly via posttranscriptional mechanisms. Moreover, we assessed immune cell and checkpoint characteristics between the high/low 3'-UTR piSNV ratio groups and predicted 80 compounds associated with the 3'-UTR piSNV-affected gene expression signature. In summary, our study revealed the prevalence and clinical relevance of 3'-UTR piSNVs in cancers, and also demonstrates that in addition to affecting miRNAs, 3'-UTR piSNVs perturb RBPs binding, APA and m6A RNA modification, which emphasized the importance of considering 3'-UTR piSNVs in cancer biology.

Signaling pathways and their potential therapeutic utility in esophageal squamous cell carcinoma

Esophageal cancer is a complex gastrointestinal malignancy with an extremely poor outcome. Approximately 80% of cases of this malignancy in Asian countries including India are of squamous cell origin, termed Esophageal Squamous Cell Carcinoma (ESCC).The five-year survival rate in ESCC patients is less than 20%. Neo-adjuvant chemo-radiotherapy (NACRT) followed by surgical resection remains the major therapeutic strategy for patients with operable ESCC. However, resistance to NACRT and local recurrence after initial treatment are the leading cause of dismal outcomes in these patients. Therefore, an alternative strategy to promote response to the therapy and reduce the post-operative disease recurrence is highly needed. At the molecular level, wide variations have been observed in tumor characteristics among different populations, nevertheless, several common molecular features have been identified which orchestrate disease progression and clinical outcome in the malignancy. Therefore, determination of candidate molecular pathways for targeted therapy remains the mainstream idea of focus in ESCC research. In this review, we have discussed the key signaling pathways associated with ESCC, i.e., Notch, Wnt, and Nrf2 pathways, and their crosstalk during disease progression. We further discuss the recent developments of novel agents to target these pathways in the context of targeted cancer therapy. In-depth research of the signaling pathways, gene signatures, and a combinatorial approach may help in discovering targeted therapy for ESCC.

Absence of NOTCH1 mutation and presence of CDKN2A deletion predict progression of esophageal lesions

Currently surveillance for esophageal squamous cell carcinoma (ESCC) runs a risk of under-estimation of early lesions which show absence of iodine staining, with no or only mild histologic changes. Development of molecular markers which indicate risk of progression is thus warranted. We performed whole exome sequencing (WES) on biopsies from two sequential endoscopies of a single esophageal lesion and matching blood samples. There were 27 pairs of age, gender, pathologic stage and sampling interval matched progressors and non-progressors identified in a prospective community-based ESCC screening trial. Putative molecular progression markers for ESCC were first evaluated by comparing somatic mutation, copy number alteration (CNA) and mutational signature information among progressors and non-progressors. These markers were then validated with another 24 pairs of matched progressors and non-progressors from the same population using gene alteration status identified by target sequencing and quantitative PCR. Progressors had more somatic mutation and CNA burden, as well as apolipoprotein B mRNA editing catalytic polypeptide-like (APOBEC) and age-related signature weights as compared with non-progressors. A gene score consisting of somatic NOTCH1 mutation and CDKN2A deletion is predictive of risk of progression in lesions which show absence of iodine staining under endoscopy but have no or only mild dysplasia. This gene score was also validated in an external cohort of matched progressors and non-progressors. Absence of NOTCH1 mutation and presence of CDKN2A deletion are markers of progression in squamous lesions of the esophagus. The gene score established in this study would be ideal for assisting the pathologist identifying high-risk individuals who are potentially "missed" or subject to a risk under-estimation by histologic analysis and might improve the performance of ESCC surveillance. This article is protected by copyright. All rights reserved.

Long noncoding RNA GK-IT1 promotes esophageal squamous cell carcinoma by regulating MAPK1 phosphorylation

BACKGROUND

Long noncoding RNAs (lncRNAs) are implicated in the oncogenesis and metastasis of multiple human cancers. Nonetheless, the precise molecular mechanisms underlying the oncogenic role of lncRNA in esophageal squamous cell carcinoma (ESCC) remains to be clarified.

METHODS

The expression of GK intronic transcript 1 (GK-IT1) was analyzed using ESCC RNA-seq data from The Cancer Genome Atlas database. Quantitative real-time PCR was used to measure the expression of GK-IT1 in ESCC clinical samples and cells. The correlation between GK-IT1 expression and clinicopathological variables was examined using chi-squared tests. Kaplan-Meier survival and Cox regression analyses were employed to generate the survival curve and assess the prognostic value of GK-IT1. Functional experiments were utilized to explore the role of GK-IT1 in promoting cell migration, invasion, proliferation, and suppressing apoptosis and autophagy in ESCC. To understand the mechanism, an RNA pulldown assay, RNA immunoprecipitation, agarose gel electrophoresis, immunofluorescence, and co-immunoprecipitation assays were used.

RESULTS

In this study we identified an unreported lncRNA, termed GK-IT1 that was aberrantly overexpressed in ESCC tissues and cells. GK-IT1 was closely associated with advanced clinical stage, and it was an independent prognostic indicator of ESCC. Functional assays verified that GK-IT1 significantly promoted ESCC proliferation, invasion, and migration, and suppressed ESCC apoptosis and autophagy. Furthermore, tumorigenesis experiments in nude mice indicated that GK-IT1 promoted ESCC tumor growth and metastasis. Mechanistically, GK-IT1 competitively bound to mitogen-activated protein kinase 1 (MAPK1) to prevent the interaction between dual specificity phosphatase 6 (DUSP6) and MAPK1, thereby controlling the phosphorylation of MAPK1 and promoting ESCC progression.

CONCLUSION

Our study revealed that GK-IT1 competed with DUSP6 to attenuate the interaction between DUSP6 and MAPK1, leading to activation of the ERK/MAPK pathway, thereby promoting progression of ESCC. Our research indicated that GK-IT1 served as a novel potential target for the diagnosis and treatment of ESCC.

FAT1 downregulation enhances stemness and cisplatin resistance in esophageal squamous cell carcinoma

Primary or acquired drug resistance accounts for the failure of chemotherapy and cancer recurrence in esophageal squamous cell carcinoma (ESCC). However, the aberrant mechanisms driving drug resistance are not fully understood in ESCC. In our previous study, FAT Atypical Cadherin 1 (FAT1) was found to inhibit the epithelial-mesenchymal transition (EMT) process in ESCC. EMT plays a critical role in the development of drug resistance in multiple cancer types. Besides, it equips cancer cells with cancer stem cell (CSC)-like characters that also are associated with chemotherapy resistance. Whether FAT1 regulates the stemness or drug resistance of ESCC cells is worth being explored. Here we found that FAT1 was downregulated in ESCC spheres and negatively correlated with stemness-associated markers including ALDH1A1 and KLF4. Knocking down FAT1 enhanced the sphere-forming ability, resistance to cisplatin and drug efflux of ESCC cells. Additionally, FAT1 knockdown upregulated the expression of drug resistance-related gene ABCC3. Furtherly, we found FAT1 knockdown induced the translocation of β-catenin into nucleus and enhanced its transcriptional activity. The result of ChIP showed that β-catenin was enriched in ABCC3 promoter. Furthermore, β-catenin promoted expression of ABCC3. In conclusion, FAT1 knockdown might enhance the stemness and ABCC3-related cisplatin resistance of ESCC cells via Wnt/β-catenin signaling pathway. FAT1 and its downstream gene ABCC3 might be potential targets for overcoming chemoresistance in ESCC.