Unveiling the role of AGT in lipid metabolism and regulated cell death in colon cancer.

BACKGROUND: Lipid metabolism and regulated cell death (RCD) play a role in the remodeling of tumor immune microenvironment and regulation of cancer progression. Since the underlying immune mechanisms of colon cancer remain elusive, this study aims to identify potential therapeutic target genes. METHODS: Differential genes related to lipid metabolism and RCD in COAD patients were identified using R language and online tools. Based on the expression of genes, two groups were classified using consensus clustering. CIBERSORT and ssGSEA were used to detect immune infiltration in both groups. Prognostic signature genes for colon cancer were screened using machine learning algorithms. KEGG, GO and GSEA for gene pathway enrichment. In addition, interacting genes in the immune module were obtained using a weighted gene co-expression network (WGCNA). Finally, expression and mutation of key in colon cancer genes were detected using TIMER, HPR, cBioPortal website and qPCR. RESULTS: The consensus clustering analysis revealed that 231 relevant differential genes were highly associated with immune infiltration. A series of machine learning and website analyses identified AGT as a hub gene linked to lipid metabolism and regulated cell death, which is overexpressed in colon cancer. CONCLUSION: AGT, as a signature gene of lipid metabolism and regulated cell death, plays a critical role in the development of COAD and is associated with tumor immune infiltration.

Mitochondrial energy metabolism-related gene signature as a prognostic indicator for pancreatic adenocarcinoma.

Background: Pancreatic adenocarcinoma (PAAD) is a highly malignant gastrointestinal tumor and is associated with an unfavorable prognosis worldwide. Considering the effect of mitochondrial metabolism on the prognosis of pancreatic cancer has rarely been investigated, we aimed to establish prognostic gene markers associated with mitochondrial energy metabolism for the prediction of survival probability in patients with PAAD. Methods: Gene expression data were obtained from The Cancer Genome Atlas and Gene Expression Omnibus databases, and the mitochondrial energy metabolism-related genes were obtained from the GeneCards database. Based on mitochondrial energy metabolism score (MMs), differentially expressed MMRGs were established for MMs-high and MMs-low groups using ssGSEA. After the univariate Cox and least absolute and selection operator (LASSO) analyses, a prognostic MMRG signature was used in the multivariate Cox proportional regression model. Survival and immune cell infiltration analyses were performed. In addition, a nomogram based on the risk model was used to predict the survival probability of patients with PAAD. Finally, the expression of key genes was verified using quantitative polymerase chain reaction and immunohistochemical staining. Intro cell experiments were performed to evaluated the proliferation and invasion of pancreatic cancer cells. Results: A prognostic signature was constructed consisting of two mitochondrial energy metabolism-related genes (MMP11, COL10A1). Calibration and receiver operating characteristic (ROC) curves verified the good predictability performance of the risk model for the survival rate of patients with PAAD. Finally, immune-related analysis explained the differences in immune status between the two subgroups based on the risk model. The high-risk score group showed higher estimate, immune, and stromal scores, expression of eight checkpoint genes, and infiltration of M0 macrophages, which might indicate a beneficial response to immunotherapy. The qPCR results confirmed high expression of MMP11 in pancreatic cancer cell lines, and IHC also verified high expression of MMP11 in clinical pancreatic ductal adenocarcinoma tissues. In vitro cell experiments also demonstrated the role of MMP11 in cell proliferation and invasion. Conclusion: Our study provides a novel two-prognostic gene signature-based on MMRGs-that accurately predicted the survival of patients with PAAD and could be used for mitochondrial energy metabolism-related therapies in the future.

LINC00922 decoys SIRT3 to facilitate the metastasis of colorectal cancer through up-regulation the H3K27 crotonylation of ETS1 promoter.

BACKGROUND: Lysine crotonylation (Kcr) is up-regulation in colorectal cancer (CRC) tissues, while its specific contribution remains uncertain. This study aimed to elucidate the role and mechanism of crotonylation on Lys27 of histone H3 (H3K27cr) in facilitating CRC metastasis. METHODS: Immunohistochemistry was employed to investigate the correlation between H3K27cr and CRC metastasis. Both in vitro and in vivo assays employing loss function or gain function approaches were conducted to elucidate the role of LINC00922 in promoting CRC metastasis. ScRNA-seq analysis and immunoprecipitation analyses were employed to explore the underlying mechanism by which LINC00922 facilitates CRC metastasis through H3K27cr. RESULTS: Clinically, H3K27cr was upregulated in metastatic CRC tissues and positively correlated with advanced clinical stages. Functionally, knockdown of LINC00922 inhibited migration of CRC cells both in vitro and in vivo. Furthermore, the supplementation of NaCr restored the migration and invasion levels of LINC00922 stable knockdown cells by restoring the H3K27cr level. Mechanistically, LINC00922 promoted invasion and migration through H3K27cr mediated cell adhesion molecules (CAMs) in epithelial cells. Notably, LINC00922 interacted with the protein sirtuin 3 (SIRT3) and obstructed its binding to the promoter region of ETS1, leading to an elevation in the level of H3K27cr in this promoter region and the subsequent activation of ETS1 transcription. CONCLUSIONS: Our findings uncovered a novel regulatory function of H3K27cr, regulated by LINC00922, in facilitating CRC metastasis. This discovery contributed to a deeper comprehension of the involvement of histone crotonylation in the metastatic process of CRC.

Identification of prognostic melatonin-related lncRNA signature in tumor immune microenvironment and drug resistance for breast cancer.

BACKGROUND: Melatonin is a neurohormone involved in diverse physiological processes, including regulation of circadian rhythm, oncogenesis and immune function. More attention are focused on the molecular events surrounding the occurrence of abnormally expressed lncRNAs leading to breast cancer. The purpose of this study was to evaluate the role of melatonin-related lncRNAs in the clinical management of BRCA patients and their immune responses. METHODS: The transcriptome data and clinical data of BRCA patients were acquired from TCGA database. A total of 1103 patients were randomly assigned to either training set or validation set. A melatonin-related lncRNA signature was constructed in the training set and verified in the validation set. Functional analysis, immune microenvironment and drug resistance analysis associated to melatonin-related lncRNAs were performed by utilizing GO&KEGG, ESTIMATE and TIDE analysis. A nomogram based on the signature score and clinical characteristics was established, which was calibrated to increase prediction probability of 1-year, 3-year and 5-year survival for BRCA patients. RESULTS: BRCA patients were divided into two signature groups based on a 17-melatonin-related lncRNA signature. High-signature patients had worse prognosis than low-signature patients (p < 0.001). Univariate and multivariate Cox regression analysis proved that the signature score was an independent prognostic factor for BRCA patients. Functional analysis indicated that high-signature BRCA involved in regulation of processing and maturation of mRNA and misfolded protein response. Remarkably, immune microenvironment analysis showed that the proportion of tumor-infiltrating M2 macrophage and the expression of CTLA4 were significantly higher in high-signature BRCA. The calibration curves for the probability of invasive BRCA showed optimal agreement between the probability as predicted by the nomogram and the actual probability. CONCLUSIONS: A novel melatonin-related lncRNA signature was considered as an independent prognostic indicator for BRCA patients. Melatonin-related lncRNAs were potentially associated with tumor immune microenvironment and might be therapeutic targets for BRCA patients.

Reduction of H3K27cr Modification During DNA Damage in Colon Cancer.

DNA damage plays an essential role in the initiation and development of colon cancer. Histone crotonylation is a newly discovered post-translational modification that is thought to promote gene expression. Whether histone crotonylation plays a role in DNA damage of cancer remains unknown, as does the putative underlying molecular mechanism. This study aimed to investigate the relationship between histone crotonylation and DNA damage of colon cancer using multiple bioinformatics analysis and western blotting. We discovered that genes with promoter occupied by histone crotonylation were associated with the activity of DNA damage in colon cancer patients. Additionally, we uncovered that the level of crotonylation on Lys27 of histone H3 (H3K27cr) decreased during camptothecin and etoposide treatment. Interestingly, sirtuin 6 was found to regulate the cellular level of H3K27cr. Taking these data together, our study provided a new perspective about histone crotonylation and DNA damage in colon cancer.

A Class of Protein-Coding RNAs Binds to Polycomb Repressive Complex 2 and Alters Histone Methylation.

Polycomb repressive complex 2 (PRC2) is a multi-subunit protein complex mediating the methylation of lysine 27 on histone H3 and playing an important role in transcriptional repression during tumorigenesis and development. Previous studies revealed that both protein-coding and non-coding RNAs could bind to PRC2 complex. However, the functions of protein-coding RNAs that bind to PRC2 complex in tumor are still unknown. Through data mining and RNA immunoprecipitation (RIP) assay, our study found that there were a class of protein-coding RNAs bound to PRC2 complex and H3 with tri-methylation on lysine 27. The Bayesian gene regulatory network analysis pointed out that these RNAs regulated the expression of PRC2-regulated genes in cancer. In addition, gene set enrichment analysis (GSEA), gene ontology (GO) analysis, and weighted gene co-expression network analysis (WGCNA) also confirmed that these RNAs were associated with histone modification in cancer. We also confirmed that MYO1C, a PRC2-bound transcript, inhibited the modification level of H3K27me3. Further detailed study showed that TMEM117 regulated TSLP expression through EZH2-mediated H3K27me3 modification. Interestingly, the RNA recognition motif of PRC2 complex might help these RNAs bind to the PRC2 complex more easily. The same regulatory pattern was found in mice as well.

Salusin-α Inhibits Proliferation and Migration of Vascular Smooth Muscle Cell via Akt/mTOR Signaling.

BACKGROUND/AIMS: The proliferation and migration of vascular smooth muscle cells (VSMCs) are key steps in the progression of atherosclerosis. The aim of the present study was to investigate the potential roles of salusin-α in the functions of VSMCs during the development of atherosclerosis. METHODS: In vivo, the effects of salusin-α on atherogenesis were examined in rabbits fed a cholesterol diet. The aortas were en face stained with Sudan IV to evaluate the gross atherosclerotic lesion size. The cellular components of atherosclerotic plaques were analyzed by immunohistochemical methods. In vitro, Cell Counting Kit-8 and wound-healing assays were used to assess the effects of salusin-α on VSMC proliferation and migration. In addition, western blotting was used to evaluate the total and phosphorylated levels of Akt (also known as protein kinase B) and mammalian target of rapamycin (mTOR) in VSMCs. RESULTS: Salusin-α infusion significantly reduced the aortic lesion areas of atherosclerosis, with a 39% reduction in the aortic arch, a 71% reduction in the thoracic aorta, and a 71% reduction in the abdominal aorta; plasma lipid levels were unaffected. Immunohistochemical staining showed that salusin-α decreased both macrophage- and VSMC-positively stained areas in atherosclerotic lesions by 54% and 69%, cell proliferative activity in the intima and media of arteriosclerotic lesions, and matrix metalloproteinase 2 (MMP-2) and MMP-9 expression in plaques. Studies using cultured VSMCs showed that salusin-α decreased VSMC migration and proliferation via reduced phosphorylation of Akt and mTOR. CONCLUSION: Our data indicate that salusin-α suppresses the development of atherosclerosis by inhibiting VSMC proliferation and migration through the Akt/mTOR pathway.

Differential Patterns of Secreted Frizzled-Related Protein 4 (SFRP4) in Adipocyte Differentiation: Adipose Depot Specificity.

BACKGROUND/AIMS: Secreted frizzled-related protein 4 (SFRP4) is a member of the SFRP family that acts as soluble modulators of Wnt signaling. Given the substantial rise in obesity, depot-specific fat accumulation and its associated diseases like diabetes, it is important to understand the molecular basis of depot-specific adipocyte differentiation. In the current study, we investigated the expression of SFRP4 in both subcutaneous and visceral adipose tissue in terms of their differentiation. METHODS: White preadipocytes were isolated from the inguinal white adipose tissue (iWAT) and epididymal white adipose tissue (eWAT) from C57BL/6J mice (age: 8-week-old, male). SFRP4 expression in iWAT and eWAT preadipocytes was silenced by siRNA transfection and harvested cells for gene and protein expression analysis was performed during the differentiation. Furthermore, iWAT and eWAT preadipocytes treated with or without IL-1ß were harvested for gene and protein expression analysis. RESULTS: SFRP4 expression levels were gradually increased and proportionally associated with eWAT adipocyte differentiation toward maturation at 14 days, while iWAT adipocyte just showed an opposite tendency. Moreover, genetic (adiponectin, C/EBPα, C/EBPß, FABP4, GLUT4 and PPARγ) analysis demonstrated that depot-specific adipogenesis in response to SFRP4 silencing in eWAT and iWAT preadipocytes. Upon IL-1ß treatment, SFRP4 mRNA expression decreased significantly in iWAT adipocyte, but the expression was no significant difference in eWAT adipocyte. CONCLUSION: These results suggest that SFRP4 expression differentially mediates adipocyte differentiation and may play an important role in adipogenesis.