O6-methylguanine DNA methyltransferase is upregulated in malignant transformation of gastric epithelial cells via its gene promoter DNA hypomethylation

Mitochondrial Complex I Molecular Alterations in Sapajus apella as a Human Gastric Carcinogenesis Model After MNU Exposure

INTRODUCTION

Gastric cancer (GC) remains among the top five global health problems. Therefore, comprehending the tumor energetic behavior is critical to understanding its progression. This study aimed to investigate mitochondrial DNA (mtDNA) alterations in GC cancer cell lines in an animal model.

MATERIAL AND METHODS

Four mitochondrial genes (COI, ATP8, ND1, and ND3) were analyzed in GC (AGP01, ACP02, ACP03, and PG100) and control (Walker 256 carcinosarcoma) cell lines inoculated in Sapajus apella, exposed and not exposed to N-methyl-N-nitrosourea.

RESULTS

Two synonymous alterations were identified in ND1. In ND3, a non-synonymous alteration (A10398G ➔ Thr114Ala) may decrease the respiratory chain Complex I efficiency, enhancing cellular reactive oxygen species and contributing to mtDNA damage. As alterations in ND1 and ND3 were observed in highly aggressive cell lines, our results suggest these genes may play crucial roles in energetic efficiency and gastric carcinogenesis.

A review of potential mechanisms and treatments of gastric intestinal metaplasia

Gastric intestinal metaplasia (GIM) is a pathological process where gastric mucosal epithelial cells are replaced by intestinal-type cells, serving as a precursor lesion for gastric cancer. This transformation involves various genetic and environmental factors, affecting key genes and signaling pathways. Recent research has revealed complex mechanisms, including changes in gene expression, abnormal signaling pathway activation, and altered cell behavior. This review summarizes the latest research on GIM, discussing its pathogenesis, current treatment strategies, and potential efficacy of emerging approaches like gene editing, microbiome interventions, and integrative medicine. By exploring these strategies, we aim to provide more effective treatments for GIM and reduce gastric cancer incidence. The review also highlights the importance of interdisciplinary studies in understanding GIM mechanisms and improving treatment strategies.

Construction of a chemiluminescent biosensor based on enzymatic extension and click chemistry for sensitive measurement of MGMT activity in human breast tissues

O6-methylguanine methyltransferase (MGMT) is responsible for dealkylation of naturally occurring O6-methylguanines, and it is closely related with DNA replication, transcription, and cancers. Herein, we develop a chemiluminescent biosensor based on enzymatic extension and click chemistry for sensitive measurement of MGMT activity. When MGMT is present, the MGMT-catalyzed demethylation reaction initiates the cleavage of biotinylated dumbbell probes by PvuII restrictive enzyme, releasing two DNA fragments with 3'-OH end. The resultant DNA fragments can trigger terminal transferase (TdT)- and click chemistry-assisted isothermal amplification to obtain abundant G-rich sequences. The G-rich sequences can be captured by magnetic beads to produce a high chemiluminescence signal. This biosensor can greatly amplify the chemiluminescence signal, facilitating label-free and template-free measurement of MGMT. Especially, the introduction of dumbbell probe and PvuII enzyme can efficiently eliminate the false positive and improve the assay specificity. This biosensor possesses high sensitivity with a detection limit of 1.4 × 10-9 ng/μL, and it may accurately quantify the intracellular MGMT. Importantly, this biosensor can be used to screen the MGMT inhibitors and distinguish the MGMT level in breast tumor tissues and normal tissues, with great potential in drug discovery and cancer diagnosis.

YTHDF1 mediates N-methyl-N-nitrosourea-induced gastric carcinogenesis by controlling HSPH1 translation

YT521-B homology (YTH) domain family (YTHDF) proteins serve as readers that directly recognise m6A modifications. In this study, we aim to probe the role of YTHDF1 in environmental carcinogen-induced malignant transformation of gastric cells and gastric cancer (GC) carcinogenesis. We established a long-term low-dose MNU-induced malignant transformation model in gastric epithelial cells. In vivo and in vitro experiments were conducted to validate the malignant phenotype and characterise the roles of YTHDF1 and its downstream genes in malignant transformation cells. Additionally, we explored downstream m6A modification targets of YTHDF1 using RNA-sequencing, RNA immunoprecipitation, and proteomics analyses, and conducted validation experiments in cell experiments and clinical samples. Long-term low-dose exposure of MNU converted normal Gges-1 cells into malignant cells. YTHDF1 mRNA and protein expression are increased in MNU-induced malignant cells (p<0.001). Meanwhile, YTHDF1 knockdown inhibits the malignant potential of MNU-treated cells (p<0.01). YTHDF1 knockdown specifically suppresses HSPH1 protein, but not RNA levels. RIP-qPCR validates HSPH1 is the target of YTHDF1 (p<0.01). HSPH1 knockdown impairs the malignant potential of MNU-induced transformed cells. The increased expression of the key regulatory factor YTHDF1 in MNU-induced gastric carcinogenesis affects malignant transformation and tumorigenesis by regulating the translation of downstream HSPH1. These findings provide new potential targets for preventing and treating environmental chemical-induced gastric carcinogenesis.

Microbiota-Gastric Cancer Interactions and the Potential Influence of Nutritional Therapies

Gastric cancer (GC) is one of the most common causes of cancer deaths, and GC treatments represent a large area of research. Although initially regarded as a sterile organ and unsuitable for microbial communities, the discovery of Helicobacter pylori made us realize that some microbes can colonize the stomach. In recent years, growing interest in gastric bacteria has expanded to the gut microbiota and, more recently, to the oral microbiota. Indeed, the oral-gastric-gut microbiota axis may play a crucial role in maintaining homeostasis, while changes in microbiota composition in GC patients can influence clinical outcomes. On the one hand, the microbiota and its metabolites may significantly influence the progression of GC, while anti-GC treatments such as gastrectomy and chemotherapy may significantly impact the oral-gastric-gut microbiota axis of GC patients. In this context, the role of nutritional therapies, including diet, prebiotics, and probiotics, in treating GC should not be underestimated. Wit this review, we aim to highlight the main role of the gastric, oral, and gut microbiota in GC onset and progression, representing potential future biomarkers for early GC detection and a target for efficient nutritional therapies during the course of GC.

The effect of phytochemicals in N-methyl-N-nitro-N-nitroguanidine promoting the occurrence and development of gastric cancer

Gastric cancer is a common malignant tumor of the digestive tract, with a low early diagnosis rate. N-methyl-N-nitro-N-nitroguanidine (MNNG) is one of the main risk factors for gastric cancer. Phytochemicals are healthy active substances derived from vegetables, fruits, nuts, tea, herbal medicines and other plants. Taking phytochemicals is a very promising strategy for the prevention and treatment of gastric cancer. Many studies have proved that phytochemicals have protective effects on MNNG induced gastric cancer via inhibiting cell proliferation, enhancing immunity, suppressing cell invasion and migration, inducing apoptosis and autophagy, blocking angiogenesis, inhibiting Helicobacter pylori infection as well as regulating metabolism and microbiota. The intervention and therapeutic effects of phytochemicals in MNNG induced gastric cancer have attracted more and more attention. In order to better study and explore the role, advantages and challenges of phytochemicals in MNNG induced gastric cancer, we summarized the intervention and therapeutic effects of phytochemicals in MNNG induced gastric cancer. This review may help to further promote the research and clinical application of phytochemicals in MNNG induced gastric cancer, and provide some new insights.