Machine learning to establish three sphingolipid metabolism genes signature to characterize the immune landscape and prognosis of patients with gastric cancer.

BACKGROUND: Gastric cancer (GC) is one of the most common malignant tumors worldwide. Nevertheless, GC still lacks effective diagnosed and monitoring method and treating targets. This study used multi omics data to explore novel biomarkers and immune therapy targets around sphingolipids metabolism genes (SMGs). METHOD: LASSO regression analysis was performed to filter prognostic and differently expression SMGs among TCGA and GTEx data. Risk score model and Kaplan-Meier were built to validate the prognostic SMG signature and prognostic nomogram was further constructed. The biological functions of SMG signature were annotated via multi omics. The heterogeneity landscape of immune microenvironment in GC was explored. qRT-PCR was performed to validate the expression level of SMG signature. Competing endogenous RNA regulatory network was established to explore the molecular regulatory mechanisms. RESULT: 3-SMGs prognostic signature (GLA, LAMC1, TRAF2) and related nomogram were constructed combing several clinical characterizes. The expression difference and diagnostic value were validated by PCR data. Multi omics data reveals 3-SMG signature affects cell cycle and death via several signaling pathways to regulate GC progression. Overexpression of 3-SMG signature influenced various immune cell infiltration in GC microenvironment. RBP-SMGs-miRNA-mRNAs/lncRNAs regulatory network was built to annotate regulatory system. CONCLUSION: Upregulated 3-SMGs signature are excellent predictive diagnosed and prognostic biomarkers, providing a new perspective for future GC immunotherapy.

Identification of novel prognostic circRNA biomarkers in circRNA-miRNA-mRNA regulatory network in gastric cancer and immune infiltration analysis.

BACKGROUND: Gastric cancer (GC) carries significant morbidity and mortality globally. An increasing number of studies have confirmed that circular RNA (circRNA) is tightly associated with the carcinogenesis and development of GC, especially acting as a competing endogenous RNA for miRNAs. OBJECTIVE: Our study aimed to construct the circRNA-miRNA-mRNA regulatory network and analyze the function and prognostic significance of the network using bioinformatics tools. METHODS: We first downloaded the GC expression profile from the Gene Expression Omnibus database and identified differentially expressed genes and differentially expressed circRNAs. Then, we predicted the miRNA-mRNA interaction pairs and constructed the circRNA-miRNA-mRNA regulatory network. Next, we established a protein-protein interaction network and analyzed the function of these networks. Finally, we primarily validated our results by comparison with The Cancer Genome Atlas cohort and by performing qRT-PCR. RESULTS: We screened the top 15 hub genes and 3 core modules. Functional analysis showed that in the upregulated circRNA network, 15 hub genes were correlated with extracellular matrix organization and interaction. The function of downregulated circRNAs converged on physiological functions, such as protein processing, energy metabolism and gastric acid secretion. We ascertained 3 prognostic and immune infiltration-related genes, COL12A1, COL5A2, and THBS1, and built a nomogram for clinical application. We validated the expression level and diagnostic performance of key prognostic differentially expressed genes. CONCLUSIONS: In conclusion, we constructed two circRNA-miRNA-mRNA regulatory networks and identified 3 prognostic and screening biomarkers, COL12A1, COL5A2, and THBS1. The ceRNA network and these genes could play important roles in GC development, diagnosis and prognosis.

Using gastric juice lncRNA-ABHD11-AS1 as a novel type of biomarker in the screening of gastric cancer.

Long noncoding RNAs (lncRNAs) play vital roles in tumorigenesis. However, the diagnostic values of most lncRNAs are largely unknown. To investigate whether gastric juice lncRNA-ABHD11-AS1 can be a potential biomarker in the screening of gastric cancer, 173 tissue samples and 130 gastric juice from benign lesion, gastric dysplasia, gastric premalignant lesions, and gastric cancer were collected. ABHD11-AS1 levels were detected by reverse transcription-polymerase chain reaction. Then, the relationships between ABHD11-AS1 levels and clinicopathological factors of patients with gastric cancer were investigated. The results showed that ABHD11-AS1 levels in gastric cancer tissues were significantly higher than those in other tissues. Its levels in gastric juice from gastric cancer patients were not only significantly higher than those from cases of normal mucosa or minimal gastritis, atrophic gastritis, and gastric ulcers but also associated with gender, tumor size, tumor stage, Lauren type, and blood carcinoembryonic antigen (CEA) levels. More importantly, when using gastric juice ABHD11-AS1 as a marker, the positive detection rate of early gastric cancer patients was reached to 71.4 %. Thanks to the special origin of gastric juice, these results indicate that gastric juice ABHD11-AS1 may be a potential biomarker in the screening of gastric cancer.

Plasma long noncoding RNA protected by exosomes as a potential stable biomarker for gastric cancer.

Long intergenic non-protein-coding RNA 152 (LINC00152) is one of the long noncoding RNAs (lncRNAs) abnormally expressed in gastric cancer tissues. However, its value in the diagnosis of gastric cancer is unclear. The aim of this study is to evaluate the clinical significance of plasma LINC00152 as a biomarker in the screening of gastric cancer and to explore the possible mechanism underling its stable existence in blood. We analyzed the levels of plasma LINC00152 in patients with gastric cancer and gastric epithelial dysplasia and healthy controls using quantitative reverse transcription polymerase chain reaction and then confirmed by sequencing. We also compared its levels in paired preoperative and postoperative plasma samples. In addition, we compared the levels of LINC00152 in plasma and in exosomes, which were extracted from the same plasma and confirmed by transmission electron microscopy. The levels of plasma LINC00152 were significantly elevated in gastric cancer patients compared with healthy controls. The sensitivity and specificity of plasma LINC00152 in the diagnosis of gastric cancer were 48.1 and 85.2%, respectively. There were no significant differences of LINC00152 levels between gastric epithelial dysplasia patients and healthy controls. LINC00152 levels in preoperative plasma samples were lower than those in postoperative ones. There were also no differences between LINC00152 levels in plasma and in exosomes. All these results suggested that LINC00152 can be detected in plasma, and one of the possible mechanisms of its stable existence in blood was protected by exosomes. It has the possibility to be applied in gastric cancer diagnosis as a novel blood-based biomarker.

Low expression of lncRNA-HMlincRNA717 in human gastric cancer and its clinical significances.

Long noncoding RNAs (lncRNAs) have been gradually confirmed to be tumor-associated biological molecules in recent years. However, the clinical significances of most lncRNAs in the screening of gastric cancer are largely unknown. Based on our lncRNA array results, in this study, we explored the potential relationship between HMlincRNA717 expression levels and clinicopathologic factors of gastric cancer. A total of 313 samples were collected from two cancer centers, and then HMlincRNA717 level in human gastric cancer tissues and gastric cell lines was measured by real-time reverse transcription-polymerase chain reaction. Then, HMlincRNA717 levels at multiple stages of gastric tumorigenesis were investigated and the potential association between it levels, and clinicopathological features were analyzed. The expression levels of HMlincRNA717 in five gastric cancer cell lines, AGS, BGC-823, HGC-27, MGC-803, and SGC-7901, were significantly downregulated than those in normal gastric mucosal epithelial cell line GES-1. It was not only downregulated in 62.6 % (67/107) gastric cancer tissues compared with the paired adjacent normal tissues but also in gastric precancerous lesions. More importantly, our results indicated that HMlincRNA717 expression levels were correlated with cancer distal metastasis (P = 0.034), venous invasion (P = 0.029), and nervous invasion (P = 0.024). Our data suggested that lncRNA-HMlincRNA717 may play crucial roles during cancer occurrence and progression and may be a new potential biomarker of early gastric cancer.

Clinical Significance of Disulfidptosis-related Genes and Functional Analysis in Gastric Cancer.

Background: Worldwide, gastric cancer (GC) remains intractable due to its poor prognosis and high morbidity and mortality. Disulfidptosis is a novel kind of cell death mediated by abnormal accumulation of intracellular disulphides. The correlation between disulfidptosis and GC is still unknown. Therefore, it is necessary to elucidate the pathogenesis and mechanism of disulfidptosis and GC for clinical diagnosis and intervention. Methods: RNA-sequencing data from several public data portals and clinical samples were collected. We compared the expression levels of four key genes of disulfidptosis, including SLC7A11, SLC3A2, RPN1, and NCKAP1, in GC and selected prognostic genes to build a novel GC prognosis-related nomogram model. The biological functions and immune landscape of the identified prognostic genes were explored. Results: Overexpressed NCKAP1 and SLC7A11 were prognostic disulfidptosis-related genes in GC. We combined these genes and several clinicopathological factors to build a prognostic nomogram model for GC. Meanwhile, the ROC curves showed that NCKAP1 and SLC7A11 were promising biomarkers for GC screening. The biological and cellular functions were focused on actin activities, GTPase and immunoreaction. The tumour immune microenvironment and immune therapy targets were identified. Competing endogenous RNA network was built to explore the downstream regulatory mechanisms. Finally, the elevated NCKAP1 and SLC7A11 expression in GC was validated via qRT-PCR in a cell line and tissue line. Conclusion: In conclusion, NCKAP1 and SLC7A11 are promising prognostic and diagnostic biomarkers for GC that correlate with the activities of actin, energy metabolism of GTPase, immune infiltration and immunotherapy.

Human gut resistome can be country-specific.

The emergence and spread of antibiotic resistance have become emerging threats to human health. The human gut is a large reservoir for antibiotic resistance genes. The gut resistome may be influenced by many factors, but the consumption of antibiotics at both individual and country level should be one of the most significant factors. Previous studies have suggested that the gut resistome of different populations may vary, but lack quantitative characterization supported with relatively large datasets. In this study, we filled the gap by analyzing a large gut resistome dataset of 1,267 human gut samples of America, China, Denmark, and Spain. We built a stacking machine-learning model to determine whether the gut resistome can act as the sole feature to identify the nationality of an individual reliably. It turned out that the machine learning method could successfully identify American, Chinese, Danish, and Spanish populations with F1 score of 0.964, 0.987, 0.971, and 0.986, respectively. Our finding does highlight the significant differences in the composition of the gut resistome among different nationalities. Our study should be valuable for policy-makers to look into the influences of country-specific factors of the human gut resistome.

LncRNA-RMRP promotes carcinogenesis by acting as a miR-206 sponge and is used as a novel biomarker for gastric cancer.

Long noncoding RNAs (lncRNAs) play crucial roles in tumorigenesis. However, the mechanisms of most lncRNAs in cancers are largely unknown. Because the RNA component of mitochondrial RNA processing endoribonuclease (RMRP) is one of the dysregulated lncRNAs in gastric cancer, this study explored its molecular mechanisms in carcinogenesis. RMRP levels in 792 tissues, plasma and gastric juices from patients with various stages of gastric tumorigenesis were analyzed by quantitative reverse transcription-polymerase chain reaction. Overexpression and RNA interference were used to manipulate RMRP expression by RMRP expression vector and small interfering RNAs, respectively. Its mechanisms were evaluated by flow cytometry, real-time cell analysis, plate colony formation assays, and xenograft models. RMRP levels in tissue, plasma and gastric juices from patients with gastric cancer were significantly different from those from controls. Its levels were significantly associated with Borrmann type and metastasis. Plasma and gastric juice RMRP had higher sensitivity and specificity than commonly used markers (such as carcinoembryonic antigen and carbohydrate antigen 19-9). Knockdown of RMRP significantly inhibited cell proliferation in vitro and in vivo, whereas overexpression of RMRP promoted cell growth. Acting as a miR-206 sponge, RMRP modulated cell cycle by regulating Cyclin D2 expression. RMRP plays a crucial role in gastric cancer occurrence and can be used as a novel biomarker for gastric cancer.