Corrigendum: A novel ferroptosis-related LncRNA pair prognostic signature predicts immune landscapes and treatment responses for gastric cancer patients

[This corrects the article DOI: 10.3389/fgene.2022.899419.].

A Novel Ferroptosis-Related LncRNA Pair Prognostic Signature Predicts Immune Landscapes and Treatment Responses for Gastric Cancer Patients

Background: The construction of ferroptosis-related lncRNA prognostic models in malignancies has been an intense area of research recently. However, most of the studies focused on the exact expression of lncRNAs and had limited application values. Herein, we aim to establish a novel prognostic model for gastric cancer (GC) patients and discuss its correlation with immune landscapes and treatment responses.

Methods: The present study retrieved transcriptional data of GC patients from the Cancer Genome Atlas (TCGA) database. We identified differentially expressed ferroptosis-related lncRNAs between tumor and normal controls of GC samples. Based on a new method of cyclically single pairing, we constructed a 0 or 1 matrix of ferroptosis-related lncRNA pairs (FRLPs). A risk score signature consisting of 10 FRLPs was established using multi-step Cox regression analysis. Next, we performed a series of systematic analyses to investigate the association of the FRLP model and tumor microenvironment, biological function, and treatment responses. An alternative model to the FRLP risk score signature, the gene set score (GS) model was also constructed, which could represent the former when lncRNA expression was not available.

Results: We established a novel prognostic signature of 10 ferroptosis-related lncRNA pairs. High-risk patients in our risk score model were characterized by high infiltration of immune cells, upregulated carcinogenic and stromal activities, and heightened sensitivity to a wide range of anti-tumor drugs, whereas low-risk patients were associated with better responses to methotrexate treatment and elevated immunotherapeutic sensitivity. The practicability of the FRLP risk score model was also validated in two independent microarray datasets downloaded from Gene Expression Omnibus (GEO) using the GS model. Finally, two online dynamic nomograms were built to enhance the clinical utility of the study.

Conclusion: In this study, we developed a ferroptosis-related lncRNA pair-based risk score model that did not rely on the exact lncRNA expression level. This novel model might provide insights for the accurate prediction and comprehensive management for GC patients.

Cross-Talk Between m6A- and m5C-Related lncRNAs to Construct a Novel Signature and Predict the Immune Landscape of Colorectal Cancer Patients

Background

N6-methyladenosine (m⁶A) and 5-methylcytosine (m⁵C) can modify long non-coding RNAs (lncRNAs), thereby affecting tumorigenesis and tumor progression. However, there is a lack of knowledge regarding the potential roles and cross-talk of m⁶A- and m⁵C-related lncRNAs in the tumor microenvironment (TME) and their effect on prognosis.

Methods

We systematically evaluated the expression patterns of m⁶A- and m⁵C-related lncRNAs in 1358 colorectal cancer (CRC) samples from four datasets. Consensus clustering was conducted to identify molecular subtypes of CRC, and the clinical significance, TME, tumor-infiltrating immune cells (TIICs), and immune checkpoints in the different molecular subtypes were analyzed. Finally, we established a m⁶A- and m⁵C-related lncRNA signature and a prognostic nomogram.

Results

We identified 141 m⁶A- and m⁵C-related lncRNAs by co-expression analysis, among which 23 lncRNAs were significantly associated with the overall survival (OS) of CRC patients. Two distinct molecular subtypes (cluster A and cluster B) were identified, and these two distinct molecular subtypes could predict clinicopathological features, prognosis, TME stromal activity, TIICs, immune checkpoints. Next, a m⁶A- and m⁵C-related lncRNA signature for predicting OS was constructed, and its predictive capability in CRC patients was validated. We then constructed a highly accurate nomogram for improving the clinical applicability of the signature. Analyses of clinicopathological features, prognosis, TIICs, cancer stem cell (CSC), and drug response revealed significant differences between two risk groups. In addition, we found that patients with a low-risk score exhibited enhanced response to anti-PD-1/L1 immunotherapy. Functional enrichment analysis showed that these lncRNAs related to the high-risk group were involved in the development and progression of CRC.

Conclusions

We conducted a comprehensive analysis of m⁶A- and m⁵C-related lncRNAs in CRC and revealed their potential functions in predicting tumor-immune-stromal microenvironment, clinicopathological features, and prognosis, and determined their role in immunotherapy. These findings may improve our understanding of the cross-talk between m⁶A- and m⁵C-related lncRNAs in CRC and pave a new road for prognosis assessment and more effective immunotherapy strategies.

Systemic inflammatory response syndrome is triggered by mitochondrial damage (Review)

Mitochondria are key organelles of cellular energy metabolism; both mitochondrial function and metabolism determine the physiological function of cells and serve an essential role in immune responses. Key damage-associated molecular patterns (DAMPs), such as mitochondrial DNA and N-formyl peptides, released following severe trauma-induced mitochondrial damage may affect the respiratory chain, enhance oxidative stress and activate systemic inflammatory responses via a variety of inflammation-associated signaling pathways. Severe trauma can lead to sepsis, multiple organ dysfunction syndrome and death. The present review aimed to summarize the pathophysiological mechanisms underlying the effects of human mitochondrial injury-released DAMPs on triggering systemic inflammatory responses and to determine their potential future clinical applications in preventing and treating sepsis.

Identification of Subtypes and a Prognostic Gene Signature in Colon Cancer Using Cell Differentiation Trajectories

Research on the heterogeneity of colon cancer (CC) cells is limited. This study aimed to explore the CC cell differentiation trajectory and its clinical implication and to construct a prognostic risk scoring (RS) signature based on CC differentiation-related genes (CDRGs). Cell trajectory analysis was conducted on the GSE148345 dataset, and CDRG-based molecular subtypes were identified from the GSE39582 dataset. A CDRG-based prognostic RS signature was constructed using The Cancer Genome Atlas as the training set and GSE39582 as the validation set. Two subsets with distinct differentiation states, involving 40 hub CDRGs regulated by YY1 and EGR2, were identified by single-cell RNA sequencing data, of which subset I was related to hypoxia, metabolic disorders, and inflammation, and subset II was associated with immune responses and ferroptosis. The CDRG-based molecular subtypes could successfully predict the clinical outcomes of the patients, the tumor microenvironment status, the immune infiltration status, and the potential response to immunotherapy and chemotherapy. A nomogram integrating a five-CDRG-based RS signature and prognostic clinicopathological characteristics could successfully predict overall survival, with strong predictive performance and high accuracy. The study emphasizes the relevance of CC cell differentiation for predicting the prognosis and therapeutic response of patients to immunotherapy and chemotherapy and proposes a promising direction for CC treatment and clinical decision-making.

Proximal gastrectomy with double-tract reconstruction versus total gastrectomy for proximal early gastric cancer: A systematic review and meta-analysis

BACKGROUND

The incidence of proximal gastric cancer in the gastric fundus, cardia, and other parts is increasing rapidly. The purpose of this study was to systematically compare the short-term and long-term clinical effects of proximal gastrectomy with double tract reconstruction (PG-DTR) to total gastrectomy (TG) for proximal early gastric cancer (EGC).

METHODS

A systematic review and meta-analysis was conducted through searching the literature in PubMed, Web of Science, Cochrane Library, EMBASE, CNKI, WAN FANG, and VIP databases. All clinical controlled trials and randomized controlled trials (RCTs) of PG-DTR and PG were included. Simultaneously, the relevant data were extracted, and the software RevMan version 5.1 was used for the meta-analysis.

RESULTS

Eight studies with a total of 753 patients were eligible for the meta-analysis. There were no significant differences in the operation time, intraoperative blood loss, postoperative hospital stay, early complications (anastomotic fistula and anastomotic bleeding), late complications (reflux symptoms and anastomotic stenosis), and 5-year survival rate between PG-DTR and TG. However, the levels of partial nutritional indicators (vitamin B12 supplements and vitamin B12 deficiency) were significantly higher in the PG-DTR group than in the TG group.

CONCLUSION

This study showed ample evidence to suggest that PG-DTR improved the postoperative nutritional status without compromising patient safety while providing the same surgical characteristics and postoperative morbidity as TG.

Identification of stem cell-related subtypes and risk scoring for gastric cancer based on stem genomic profiling

Background

Although numerous studies demonstrate the role of cancer stem cells in occurrence, recurrence, and distant metastases in gastric cancer (GC), little is known about the evolving genetic and epigenetic changes in the stem and progenitor cells. The purpose of this study was to identify the stem cell subtypes in GC and examine their clinical relevance.

Methods

Two publicly available datasets were used to identify GC stem cell subtypes, and consensus clustering was performed by unsupervised machine learning methods. The cancer stem cell (CSC) typing-related risk scoring (RS) model was established through multivariate Cox regression analysis.

Results

Cross-platform dataset-based two stable GC stem cell subtypes, namely low stem cell enrichment (SCE_L) and high stem cell enrichment (SCE_H), were prudently identified. Gene set enrichment analysis revealed that the classical oncogenic pathways, immune-related pathways, and regulation of stem cell division were active in SCE_H; ferroptosis, NK cell activation, and post-mutation repair pathways were active in SCE_L. GC stem cell subtypes could accurately predict clinical outcomes in patients, tumor microenvironment cell-infiltration characteristics, somatic mutation landscape, and potential responses to immunotherapy, targeted therapy, and chemotherapy. Additionally, a CSC typing-related RS model was established; it was strongly independent and could accurately predict the patient’s overall survival.

Conclusions

This study demonstrated the complex oncogenic mechanisms underlying GC. The findings provide a basis and reference for the diagnosis and treatment of GC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-021-02633-x.

Identification of pyroptosis-related subtypes, the development of a prognosis model, and characterization of tumor microenvironment infiltration in colorectal cancer

Pyroptosis is a newly discovered programmed cell death that is associated with tumor progression, prognosis, and treatment response. However, the potential roles of pyroptosis-related genes (PRGs) in the tumor microenvironment (TME) remain unclear. We described the alterations of PRGs in 1109 colorectal cancer (CRC) samples from genetic and transcriptional fields and evaluated their expression patterns from four independent datasets. We identified two distinct molecular subtypes and found that multi-layer PRG alterations were correlated with patient clinicopathological features, prognosis, and TME cell-infiltrating characteristics. Then, a PRG_score for predicting recurrence-free survival (RFS) was constructed and its predictive capability in CRC patients was validated. Consequently, we constructed a highly accurate nomogram for improving the clinical applicability of the PRG_score. A low PRG_score, characterized by increased microsatellite instability-high (MSI-H), mutation burden, and immunity activation, indicated favorable odds of RFS. Moreover, the PRG_score was significantly associated with the cancer stem cell (CSC) index and chemotherapeutic drug sensitivity. Our comprehensive analysis of PRGs in CRC demonstrated their potential roles in the tumor-immune-stromal microenvironment, clinicopathological features, and prognosis. These findings may improve our understanding of PRGs in CRC and pave a new path for the assessment of prognosis and the development of more effective immunotherapy strategies.

Pyroptosis Patterns Characterized by Distinct Tumor Microenvironment Infiltration Landscapes in Gastric Cancer

BACKGROUND

The potential role of pyroptosis in tumor microenvironment (TME) reprogramming and immunotherapy has received increasing attention. As most studies have concentrated on a single TME cell type or a single pyroptosis regulator (PR), the overall TME cell-infiltrating characteristics mediated by the integrated roles of multiple PRs have not been comprehensively recognized.

METHODS

This study curated 33 PRs and conducted consensus clustering to identify distinct pyroptosis patterns in gastric cancer (GC) patients. A single-sample gene set enrichment analysis algorithm was used to quantify the infiltration density of TME immune cells and the enrichment scores of well-defined biological signatures. The pyroptosis patterns of individuals were quantified using a principal component analysis algorithm called the pyroptosis score (PS).

RESULTS

Three distinct pyroptosis patterns with significant survival differences were identified from 1422 GC samples; these patterns were closely associated with three TME cell-infiltrating landscapes-namely, the immune-inflamed, immune-excluded, and immune-desert phenotypes. The PS model generated on the basis of the pyroptosis pattern-related signature genes could accurately predict the TME status, existing molecular subtypes, genetic variation, therapeutic response, and clinical outcome; among which, a relatively high PS was highly consistent with immune activation, molecular subtypes with survival advantages, high tumor mutation burden, high microsatellite instability, and other favorable characteristics. In particular, from the Cancer Genome Atlas database, the PS model exhibited significant prognostic relevance in a pan-cancer analysis, and patients with a relatively high PS exhibited durable therapeutic advantages and better prognostic benefits in anti-PD1/L1 therapy.

CONCLUSIONS

This study demonstrates that pyroptosis is prominently correlated with TME diversity and complexity, and quantification of the pyroptosis patterns of individuals will enhance our cognition of TME infiltration landscapes and help in formulating more effective immunotherapeutic strategies.

N6-Methyladenosine-Related lncRNA Signature Predicts the Overall Survival of Colorectal Cancer Patients

Background: The N6-methyladenosine (m6A) RNA modification can modify long non-coding RNAs (lncRNAs), thereby affecting the tumorigenesis and progression of tumors. However, the underlying role of m6A-modified lncRNAs in colorectal cancer (CRC) remains largely unknown. Therefore, our aim was to assess the prognostic value of m6A-modified lncRNAs in CRC patients. Methods: The gene expression and clinicopathological data of CRC were extracted from The Cancer Genome Atlas (TCGA) database. Pearson correlation analysis was used to investigate the m6A-modified lncRNAs. Consensus clustering was conducted to identify molecular subtypes of CRC, and the clinical significance of molecular subtypes was identified. The least absolute shrinkage and selection operator analysis (LASSO) was applied to establish a risk signature. Finally, a prognostic nomogram with risk score and clinicopathological variables was established. Results: In total, 29 m6A-modified lncRNAs were identified as prognostic lncRNAs. Two molecular clusters were identified and significant differences were found with respect to clinicopathological features and prognosis. Cluster1 is associated with poor overall survival (OS), down-regulation of Programmed cell death ligand-1 (PD-L1) expression, lower immune score, and less immune cell infiltration. Then, an m6A-modified lncRNA signature for predicting OS was constructed in the TCGA training cohort. The signature demonstrated favorable prediction performance in both training and validation sets. Compared with low-risk patients, patients with high risk showed worse clinical outcomes, lower immune scores, and downregulated PD-L1 expression. Further analysis indicated that the signature was an independent prognostic indicator, and then a prognostic nomogram based on risk score, tumor location, and tumor stage was established. Conclusions: Our study identified a seven m6A-modified lncRNA signature and established a prognostic nomogram that reliably predicts OS in CRC. These findings may improve the understanding of m6A modifications in CRC and provide insights into the prognosis and treatment strategy of CRC.

Risk factors for mortality in patients over 70 years old with COVID-19 in Wuhan at the early break: retrospective case series

BACKGROUND

Elderly patients with COVID-19 were shown to have a high case-fatality rate. We aimed to explore the risk factors associated with death in patients over 70 years old (yr).

METHODS

In this retrospective study, we enrolled consecutively hospitalized patients over 70 yr with COVID-19 between January 20 and February 15, 2020 in Renmin Hospital of Wuhan University. Epidemiological, demographic, and clinical data were collected. Clinical subtypes, including mild, moderate, severe, and critical types, were used to evaluate the severity of disease. Patients were classified into two groups: survivor and non-survivor groups. Clinical data were compared between the two groups. Univariable and multivariable Cox regression methods were used to explore the risk factors.

RESULTS

A total of 147 patients were enrolled. The case-fatality rate was 28.6%. Multivariable Cox proportional hazard regression showed that clinical subtypes, including the severe type (HR = 2.983, 95% CI: 1.231-7.226, P = 0.016) and the critical type (HR = 3.267, 95%CI: 1.009-10.576, P = 0.048), were associated with increasing risk of death when compared with the general type. Blood urea nitrogen greater than 9.5 mmol/L (HR = 2.805, 95% CI: 1.141-6.892, P = 0.025) on admission was an independent risk factor for death among laboratory findings.

CONCLUSION

The patients over 70 yr with COVID-19 had a high case-fatality rate. The risk factors, including clinical subtypes and blood urea nitrogen greater than 9.5 mmol/L, could help physicians to identify elderly patients with poor clinical outcomes at an early stage.

A Nomogram for Predicting Multiple Metastases in Metastatic Colorectal Cancer Patients: A Large Population-Based Study

OBJECTIVES

The present study aims to discover the risk factors of multiple metastases and develop a functional nomogram to forecast multiple metastases in metastatic colorectal cancer (mCRC) patients.

METHODS

mCRC cases were retrospectively collected from the Surveillance, Epidemiology, and End Results (SEER) database between 2010 and 2016. Survival times between multiple metastases and single metastasis were compared using Kaplan-Meier analysis and log-rank tests. Risk factors for multiple metastases were determined by univariate and multivariate logistic regression analyses, and a nomogram was developed to forecast the probability of multiple metastases in mCRC patients. We assessed the nomogram performance in terms of discrimination and calibration, including concordance index (C-index), area under the curve (AUC), and decision curve analysis (DCA). Bootstrap resampling was used as an internal verification method, and at the same time we select external data from Renmin Hospital of Wuhan University as independent validation sets.

RESULTS

A total of 5,302 cases were included in this study as training group, while 120 cases were as validation group. The patients with single metastasis and multiple metastases were 3,531 and 1,771, respectively. The median overall survival (OS) and cancer-specific survival (CSS) for patients with multiple metastases or single metastasis were 19 vs. 31 months, and 20 vs. 33 months, respectively. Based on the univariate and multivariate analyses, clinicopathological characteristics were associated with number of metastasis and were used to establish nomograms to predict the risk of multiple metastases. The C-indexes and AUC for the forecast of multiple metastases were 0.715 (95% confidence interval (CI), 0.707-0.723), which showed the nomogram had good discrimination and calibration curves of the nomogram showed no significant bias from the reference line, indicating a good degree of calibration. In the validation group, the AUC was 0.734 (95% CI, 0.653-0.834), and calibration curve also showed no significant bias, indicating the favorable effects of our nomogram.

CONCLUSIONS

We developed a new nomogram to predict the risk of multiple metastases. The nomogram shows the good prediction effect and can provide assistance for clinical diagnosis and treatment.

Ferroptosis-related genes are potential prognostic molecular markers for patients with colorectal cancer

Ferroptosis is a newly discovered programmed cell death that plays a vital role in the occurrence and development of tumors. However, little is known about its prognostic value of ferroptosis-related genes (FRGs) in colorectal cancer (CRC). This study was to investigate the clinical significance of FRGs on overall survival (OS) of patients with CRC. The mRNA expression profiles and corresponding clinical data of CRC patients were downloaded from public databases. Least absolute shrinkage and selection operator (LASSO) Cox regression was applied to identify hub FRGs and establish a novel ferroptosis-related gene signature in predicting OS in training cohort, and assessed in the validation cohort. Then, the genomic-clinicopathologic nomogram integrating risk scores and clinicopathological features were established. Thirteen FRGs were identified to be most significantly related to the OS of CRC patients. Based on the LASSO Cox regression algorithm, we selected 10 genes from 13 FRGs to establish a prognostic risk signature. The log-rank test and Kaplan-Meier analysis confirmed the predictive value of the risk scores for OS in CRC patients. The time-dependent receiver operating characteristic (tdROC) of signature indicates the showed powerful prediction ability in both training cohort and validation cohort. Then, a genomic-clinicopathologic nomogram integrating age, stage, and risk scores was established and demonstrated high predictive accuracy and clinical value, which was validated through tdROC and calibration curves. The ferroptosis-related gene signature and genomic-clinicopathologic nomogram could be used to predict the prognosis of CRC patients and might also be potential therapeutic targets.

Cell differentiation trajectory predicts patient potential immunotherapy response and prognosis in gastric cancer

The purpose of this study was to investigate the differentiation trajectory of gastric cancer (GC) cells and its clinical relevance and generate a prognostic risk scoring (RS) signature based on GC differentiation-related genes (GDRGs) to predict overall survival (OS). Integrated single-cell RNA sequencing (scRNA-seq) and bulk RNA-seq data from GC samples were used for analysis. The cell differentiation trajectory analysis identified three subsets with distinct differentiation states, of which subsets I/II were involved in metabolic disorders, subset II were also associated with hypoxia tolerance, and subset III were related to immune-related pathways. GC samples were divided into three GDRG-based molecular subtypes, and it was found that molecular typing based on cell differentiation successfully predicted patient OS, clinicopathological features, immune infiltration status, and immune checkpoint gene expression. An eight-GDRG-based prognostic RS signature was generated, and the OS of the high-risk group was significantly worse than that of the low-risk group. By integrating the GDRG-based RS signature with prognostic clinicopathological characteristics, a clinicopathologic-genomic nomogram was constructed, and this nomogram yielded strong predictive performance and high accuracy. The study highlights the implication of GC cell differentiation for predicting patient clinical outcome and potential immunotherapy response and proposes a promising treatment direction for GC.

Resveratrol Suppresses Severe Acute Pancreatitis-Induced Microcirculation Disturbance through Targeting SIRT1-FOXO1 Axis

BACKGROUND

Resveratrol (RSV), one of the SIRT1 agonists, has the ability of alleviating severe acute pancreatitis (SAP); however, the concrete protective mechanism remains unknown. It is noteworthy that microcirculation disturbance plays a vital role in SAP, and the SIRT1/FOX1 axis can regulate microcirculation. Therefore, this study is aimed at ascertaining what is the underlying mechanism of the protective effect of RSV on SAP, and whether it is associated with alleviating microcirculation disturbance by regulating the SIRT1/FOX1 axis.

METHOD

The model of SAP was induced by retrograde injection of sodium taurodeoxycholate into the bile duct of the rats. The pancreatic wet/dry weight, ET/NO, and TXB2/6-keto-PGF1α ratios; microcirculatory function; and SIRT1 activity were examined. ELISA was used to examine the serum level of lipase, amylase, hemorheology, ET, NO, TXB2, and 6-keto-PGF1α and the content of SIRT1, VEGF, Ang I, and Ang II in the pancreas. RT-PCR was used to examine the mRNA level of VEGF, Ang I, and Ang II. Western blotting was used to detect SIRT1, FOXO1, and acetyl-FOXO1. Immunoprecipitation was used to examine the interaction of SIRT1 and FOXO1.

RESULTS

Resveratrol can significantly decrease the expression of lipase, amylase, acetyl-FOXO1, VEGF, Ang II, ET, NO, TXB2, and 6-keto-PGF1α and the ratio of wet/dry weight, ET/NO, and TXB2/6-keto-PGF1α by improving microcirculatory dysfunction and blood viscosity in SAP. Moreover, resveratrol can also promote the interaction of SIRT1 and FOXO1 and increase SIRT1 activity and the expression of SIRT1 and Ang I. The SIRT1 inhibitor, Sirtinol (EX527), obliviously reversed the effects of RSV on SAP.

CONCLUSION

Resveratrol can protect rats against SAP, and its protective mechanism is associated with suppressing microcirculation disturbance through activating SIRT1-FOXO1 axis.

Postoperative Onset and Detection of SARS-CoV-2 in Surgically Resected Specimens From Gastrointestinal Cancer Patients With Pre/Asymptomatic COVID-19

OBJECTIVE

To describe the epidemiologic features and clinical courses of gastrointestinal cancer patients with pre/asymptomatic COVID-19 and to explore evidence of SARS-CoV-2 in the surgically resected specimens.

SUMMARY BACKGROUND DATA

The advisory of postponing or canceling elective surgeries escalated a worldwide debate regarding the safety and feasibility of performing elective surgical procedures during this pandemic. Limited data are available on gastrointestinal cancer patients with pre/asymptomatic COVID-19 undergoing surgery.

METHODS

Clinical data were retrospectively collected and analyzed. Surgically resected specimens of the cases with confirmed COVID-19 were obtained to detect the expression of ACE2 and the presence of SARS-CoV-2.

RESULTS

A total of 52 patients (male, 34) with a median age 62.5 years were enrolled. All the patients presented no respiratory symptoms or abnormalities on chest computed tomography before surgery. Six patients (11.5%) experienced symptom onset and were confirmed to be COVID-19. All were identified to be preoperatively pre/asymptomatic, as 5 were with SARS-CoV-2 presenting in cytoplasm of enterocytes or macrophages from the colorectal tissues and 1 had symptom onset immediately after surgery. The case fatality rate in patients with COVID-19 was 16.7%, much higher than those without COVID-19 (2.2%).

CONCLUSIONS

Gastrointestinal cancer patients with pre/asymptomatic COVID-19 were at high risk of postoperative onset and death. At current pandemic, elective surgery should be postponed or canceled. It highlights the need for investigating the full clinical spectrum and natural history of this infection. The early colorectal tropism of SARS-CoV-2 may have major implications on prevention, diagnosis, and treatment of COVID-19.

Gastrointestinal adenocarcinoma analysis identifies promoter methylation-based cancer subtypes and signatures

Gastric adenocarcinoma (GAC) and colon adenocarcinoma (CAC) are the most common gastrointestinal cancer subtypes, with a high incidence and mortality. Numerous studies have shown that its occurrence and progression are significantly related to abnormal DNA methylation, especially CpG island methylation. However, little is known about the application of DNA methylation in GAC and CAC. The methylation profiles were accessed from the Cancer Genome Atlas database to identify promoter methylation-based cancer subtypes and signatures for GAC and CAC. Six hypo-methylated clusters for GAC and six hyper-methylated clusters for CAC were separately generated with different OS profiles, tumor progression became worse as the methylation level decreased in GAC or increased in CAC, and hypomethylation in GAC and hypermethylation in CAC were negatively correlated with microsatellite instability. Additionally, the hypo- and hyper-methylated site-based signatures with high accuracy, high efficiency and strong independence can separately predict the OS of GAC and CAC patients. By integrating the methylation-based signatures with prognosis-related clinicopathologic characteristics, two clinicopathologic-epigenetic nomograms were cautiously established with strong predictive performance and high accuracy. Our research indicates that methylation mechanisms differ between GAC and CAC, and provides novel clinical biomarkers for the diagnosis and treatment of GAC and CAC.

Development and validation of a metabolic gene signature for predicting overall survival in patients with colon cancer

The reprogramming of cellular metabolism is a hallmark of tumorigenesis. However, the prognostic value of metabolism-related genes in colon cancer remains unclear. This study aimed to identify a metabolic gene signature to categorize colon cancer patients into high- and low-risk groups and predict prognosis. Samples from the Gene Expression Omnibus database were used as the training cohort, while samples from The Cancer Genome Atlas database were used as the validation cohort. A metabolic gene signature was established to investigate a robust risk stratification for colon cancer. Subsequently, a prognostic nomogram was established combining the metabolism-related risk score and clinicopathological characteristics of patients. A total of 351 differentially expressed metabolism-related genes were identified in colon cancer. After univariate analysis and least absolute shrinkage and selection operator-penalized regression analysis, an eight-gene metabolic signature (MTR, NANS, HADH, IMPA2, AGPAT1, GGT5, CYP2J2, and ASL) was identified to classify patients into high- and low-risk groups. High-risk patients had significantly shorter overall survival than low-risk patients in both the training and validation cohorts. A high-risk score was positively correlated with proximal colon cancer (P = 0.012), BRAF mutation (P = 0.049), and advanced stage (P = 0.027). We established a prognostic nomogram based on metabolism-related gene risk score and clinicopathologic factors. The areas under the curve and calibration curves indicated that the established nomogram showed a good accuracy of prediction. We have established a novel metabolic gene signature that could predict overall survival in colon cancer patients and serve as a biomarker for colon cancer.

Analysis of Circular RNA-Related Competing Endogenous RNA Identifies the Immune-Related Risk Signature for Colorectal Cancer

Background

Recent papers have described circular RNAs (circRNAs) playing important roles in the development and progression of colorectal cancer (CRC). However, the expression profiles of circRNAs and their functions in CRC have rarely been studied. The objective was to identify circRNAs involved in the carcinogenesis and progression of CRC and to explore potential molecular mechanisms as a competitive endogenous RNA (ceRNA). Moreover, we aimed to establish an immune-related gene signature for predicting the overall survival (OS) of CRC.

Methods

The expression patterns of circRNA, miRNA, mRNA, and clinicopathological data were collected from the GEO and TCGA databases. A ceRNA network would be established, and the functional enrichment analyses were performed. The protein-protein interaction network (PPI) was constructed, and hub genes were identified using a cytohub plugin. Subsequently, an immune-related signature was developed based on mRNAs in the ceRNA network. In addition, OS-nomogram was constructed by combining an immune-related signature and clinicopathological characterization to predict the OS.

Results

We established a circRNA-miRNA-mRNA ceRNA network. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis revealed that the mRNAs were mainly enriched in neuroactive ligand-receptor interaction, Wnt signaling pathway, cell adhesion molecules (CAMs), and renin secretion. PPI network and module analysis identified 10 hub genes, and the circRNA-miRNA hub gene regulatory modules was established. After univariate and multivariate analysis, seven immune-related genes in the ceRNA network were used to construct the immune-related signature. Patients were divided into low-risk and high-risk groups, and there were significant differences in the OS. The ROC of the nomogram indicated the satisfactory accuracy and predictive power. Furthermore, we established a prognostic nomogram based on immune-related risk score and clinical characterization. The ROC and calibration curves revealed the accuracy of the nomogram. In addition, the high-risk score was positively correlated with six immune infiltrating cells (P < 0.05).

Conclusion

We screened the key genes and established a circRNA-related ceRNA network involved in CRC, which will assist in understanding the molecular mechanisms underlying the carcinogenesis and progression. Moreover, our proposed immune-based signature may predict survival and reflect the immune status of CRC patients.

Genome-wide methylation and expression profiling identify a novel epigenetic signature in gastrointestinal pan-adenocarcinomas

Aim: To identify methylation-driven genes and establish a novel epigenetic signature for gastrointestinal (GI) pan-adenocarcinomas. Materials & methods: Methylation and RNA-seq data for GI adenocarcinomas were downloaded from the Cancer Genome Atlas database. A methylation-driven gene signature was established by multivariate Cox regression analysis. We developed a prognostic nomogram using a combination of methylation-driven gene risk score and clinicopathological variables. A joint survival analysis based on gene expression and methylation was conducted to further investigate the prognostic role of methylation-driven genes. Results: An epigenetic signature was established based on five methylation-driven genes. We also established a prognostic nomogram based on methylation-driven gene risk score and clinicopathologic factors, with a favorable predictive ability. Joint survival analysis revealed that 28 methylation-driven genes could be independent prognostic factors for overall survival for GI adenocarcinomas. Conclusion: An epigenetic signature was established that effectively predicts the overall survival for GI adenocarcinomas across anatomic boundaries.

Circular RNA-Associated Competing Endogenous RNA Network and Prognostic Nomogram for Patients With Colorectal Cancer

Background: Genetic characteristics remain underutilized for establishing prognostic models for colorectal cancer (CRC). We explored the underlying regulatory mechanisms of circular RNAs (circRNAs) that act as competing endogenous RNAs (ceRNAs) and constructed a gene-based nomogram to predict overall survival (OS) in patients with CRC.

Methods: We obtained circRNA expression profiling data from the Gene Expression Omnibus (GEO) database. MicroRNA (miRNA) and mRNA expression profiles, with associated clinical data, were obtained from The Cancer Genome Atlas (TCGA). A ceRNA network was established using Cytoscape. Interactions between differential genes were analyzed, and hub genes were identified using the cytoHubba application. The R package “clusterProfiler” was used to evaluate the Gene Ontology (GO) annotations of the differentially expressed mRNAs and the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. Database-extracted patients were randomized into a training and validation cohorts. A prognostic model was developed using the training set based on multivariate Cox analyses and was then assessed in the validation set. The accuracy of the model was evaluated using discrimination and calibration plots.

Results: Thirteen circRNAs, 62 miRNAs, and 301 mRNAs were used to construct the ceRNA network; 10 hub genes were identified via the PPI network. Next, a circRNA- miRNA hub of gene-regulatory modules was established based on four differentially expressed circRNAs, eight differentially expressed miRNAs, and nine differentially expressed mRNAs (DEmRNAs). GO and KEGG pathway analyses indicated the possible association of DEmRNAs with CRC onset and progression. Multivariate analyses revealed that age, tumor stage, and CXCR5 expression were independent risk factors for OS. A CXCR5-based model was developed to predict the OS of patients with CRC in our training set. Our nomogram showed relatively good accuracy, with C-indices of 0.757 and 0.702 in the training and validation sets, respectively. The areas under the curve of the nomograms predicting 3- and 5-years OS were 0.749 and 0.805 in the training set and 0.706 and 0.779 in the validation set, respectively.

Conclusions: Our data suggested that the hsa_circ_00001666/has-mir-1229/CXCR5 axis plays an important role in the pathogenesis of CRC, thereby identifying a potential therapeutic target. The proposed CXCR5-based nomogram may also assist surgeons in devising personalized treatments for patients with this disease.

MAPT promoter CpG island hypermethylation is associated with poor prognosis in patients with stage II colorectal cancer

Background

The methylation of microtubule-associated protein tau (MAPT) was first described in patients with Alzheimer’s disease. In this study, we aim to determine if MAPT promoter CpG island is hypermethylated and whether this signature could work as a prognostic marker for patients with stage II colorectal cancer (CRC).

Methods

MAPT methylation level and CpG island methylator phenotype (CIMP) status were examined. The prognostic value of MAPT methylation was analyzed using Cox regression analysis.

Results

Amongst stage II CRC patients (n=107), hypermethylation of MAPT promoter CpG island was seen in 23.4% of them. MAPT methylation was much more frequent in patients with age ≥60 compared to age <60 (P<0.001). MAPT were preferentially methylated among proximal colon tumors or CIMP high tumors (both P<0.001). Five-year overall survival (OS) rates were 57.1% and 79.4% for patients with and without MAPT hypermethylation, respectively, HR=2.33 (95% CI, 1.19–4.57; P=0.014). MAPT hypermethylation remained an important prognostic variable for OS in multivariate analysis with a HR of 2.29 (95% CI, 1.01–5.18; P=0.047).

Conclusion

Our findings suggest that MAPT is frequently methylated and hypermethylation is associated with worse prognosis in patients with stage II CRC.

Hybrid transvaginal natural orifice transluminal endoscopic surgery of radical sigmoidectomy for sigmoid colon cancer

BACKGROUND

Transvaginal natural orifice transluminal endoscopic surgery (NOTES) is a surgical technique - "scarless" abdominal operations performed with a multi-channel endoscope passed through a natural orifice (mouth, urethra, anus, vagina etc.) and offers less invasive and more excellent cosmetic results [1]. It is regarded as safe and feasible in patients with benign disease [2,3]. The first case of pure NOTES for sigmoid colon cancer was reported in 2012 [4]. We describe here a case of curatively intended resection for early-stage sigmoid colon cancer using the hybrid transvaginal NOTES approach.

METHODS

This video demonstrates the case of a 52-year-old woman with sigmoid colon cancer treated by hybrid transvaginal NOTES. Her body mass index was 20.4 kg/m². A laparoscope was inserted above the umbilicus and tumor's position was located. Two 5 mm trocars inserted in the right lower abdominal quadrant were mainly used for the assistant's instruments to provide traction and exposure. A single-port was inserted into the abdominal cavity transvaginally through the colpotomy. Then all the procedures were performed transvaginally with conventional rigid laparoscopic instruments. The sigmoid colon was mobilized using a lateral to medial approach. Then the root of the inferior mesenteric artery and the inferior mesenteric vein were divided with absorbable clips. After complete isolation of the proximal rectum, the rectum was transected 5 cm distal to the lesion with a linear stapler inserted through the single port. The proximal resection margin of descending colon was identified and the transection of the colon was performed. The specimen was removed transvaginally. The colon was then exteriorized and the anvil was fixed in the colon. An end-to-end anastomosis was performed using a circular stapler, and a leak test was done.

RESULTS

The operative time and estimated blood loss were 182 min and 50 mL. A 20 cm long segment of sigmoid colon was resected with negative tumor margins, and 16 lymph nodes were harvested. There was no intraoperative or postoperative morbidity. The patient was with out-of-bed activity on day 1, fluid diet on day 2, bowel movement on day3, and the drainage tube and catheter removing on day 4. On day 5, she was discharged. Pathological examination revealed a moderately-differentiated adenocarcinoma: 50 × 45 × 10 mm, with growing into subserosa, without vascular or nervous invasion, pT3N0M0 and pStage IIA. There were two scars less than 5 mm and one scar less than 10 mm visible on the abdominal wall at one month. The patient was alive without recurrence after one year's follow-up.

CONCLUSION

Hybrid transvaginal NOTES of radical sigmoidectomy may be safe and feasible for selected patients with sigmoid colon cancer and give less pain, potentially low rates of complication, faster recovery, and better cosmesis. A future large study is warranted to better evaluate this procedure. Although there are many reasons for skepticism, there is undoubted interest in this field from both surgeon and patient.