Cancer remains a leading cause of mortality worldwide, with rising incidence and death rates continuing to rise. While conventional treatments such as surgery, radiotherapy, and chemotherapy form the backbone of cancer care, they are often limited by adverse effects, recurrence risk, and incomplete tumor eradication. Tumor immunotherapy—particularly immune checkpoint inhibitors and chimeric antigen receptor (CAR) T cell therapy—has emerged as a transformative approach by activating and reprogramming anti-tumor immune responses. Despite these advances, significant challenges persist, including limited response rates to checkpoint inhibitors, the immunosuppressive nature of the tumor microenvironment (TME), and resistance mechanisms employed by tumor cells. Growing evidence suggests that immune cell senescence is a critical contributor to TME-driven immunosuppression. Senescent immune cells exhibit functional decline, elevated expression of inhibitory immune checkpoint molecules, and increased secretion of pro-inflammatory cytokines, collectively impairing anti-tumor immunity and reducing the efficacy of immunotherapy. This review highlights the role of immune cell senescence in shaping the immunosuppressive TME and driving resistance to immunotherapy. It further discusses emerging therapeutic strategies that combine immunotherapy with senescence-targeting interventions, aiming to provide novel insights into the development of more effective cancer treatment strategies.

Background and Objectives: Small gastrointestinal stromal tumors (GISTs) are defined as tumors less than 2 cm in diameter, which are often found incidentally during gastroscopy. There is controversy regarding the management of small GISTs, and a certain percentage of small GISTs become malignant during follow-up. Previous studies which used Sanger targeted sequencing have shown that the mutation rate of small GISTs is significantly lower than that of large tumors. The aim of this study was to investigate the overall mutational profile of small GISTs, including those of wild-type tumors, using whole-exome sequencing (WES) and Sanger sequencing. Methods: Thirty-six paired small GIST specimens, which were resected by endoscopy, were analyzed by WES. Somatic mutations identified by WES were confirmed by Sanger sequencing. Sanger sequencing was performed in an additional 38 small gastric stromal tumor samples for examining hotspot mutations in KIT, PDGFRA, and BRAF. Results: Somatic C-KIT/PDGFRA mutations accounted for 81% of the mutations, including three novel mutation sites in C-KIT at exon 11, across the entire small gastric stromal tumor cohort (n = 74). In addition, 15% of small GISTs harbored previously undescribed BRAF-V600E hotspot mutations. No significant correlation was observed among the genotype, pathological features, and clinical classification. Conclusions: Our data revealed a high overall mutation rate (~96%) in small GISTs, indicating that genetic alterations are common events in early GIST generation. We also identified a high frequency of oncogenic BRAF-V600E mutations (15%) in small GISTs, which has not been previously reported.

Digestive-system cancers represent major threats to human health; however, the mechanisms underlying tumorigenesis and radiochemotherapy resistance have remained elusive. Therefore, an urgent need exists for identifying key drivers of digestive system tumorigenesis and novel targeted therapeutics. The checkpoint kinase 2 (Chk2) regulates cell-cycle progression, and Chk2 dysregulation or Chk2 mutations can lead to the development of various cancers, which makes Chk2 an important research topic. This review summarizes the roles of Chk2 in DNA-damage responses, cell-cycle regulation, autophagy, and homeostasis maintenance. We describe relationships between tumorigenesis and cell-cycle dysregulation induced by Chk2 mutations. In addition, we summarize evidence indicating that Chk2 can serve as a novel therapeutic target, based on its contributions to radiochemotherapy-resistance reversion and progress made in developing antitumor agents against Chk2. The prevailing evidence supports the conclusion that further research on Chk2 will provide a deeper understanding of digestive-system tumorigenesis and should suggest novel therapeutic targets. (c) 2023 The Authors. Publishing services by Elsevier B.V. on behalf of KeAi Communications Co., Ltd. This is an open access article under the CC BY license (http://creativecommons.org/ licenses/by/4.0/).

Introduction: Pancreatic ductal adenocarcinoma (PDAC) has the highest mortality rate among all solid tumors. Tumorigenesis is promoted by the oncogene KRAS, and KRAS mutations are prevalent in patients with PDAC. Therefore, a comprehensive understanding of the interactions between KRAS mutations and PDAC may expediate the development of therapeutic strategies for reversing the progression of malignant tumors. Our study aims at establishing and validating a prediction model of KRAS mutations in patients with PDAC based on survival analysis and mRNA expression.Methods: A total of 184 and 412 patients with PDAC from The Cancer Genome Atlas (TCGA) database and the International Cancer Genome Consortium (ICGC), respectively, were included in the study.Results: After tumor mutation profile and copy number variation (CNV) analyses, we established and validated a prediction model of KRAS mutations, based on survival analysis and mRNA expression, that contained seven genes: CSTF2, FAF2, KIF20B, AKR1A1, APOM, KRT6C, and CD70. We confirmed that the model has a good predictive ability for the prognosis of overall survival (OS) in patients with KRAS-mutated PDAC. Then, we analyzed differential biological pathways, especially the ferroptosis pathway, through principal component analysis, pathway enrichment analysis, Gene Ontology (GO) enrichment analysis, and gene set enrichment analysis (GSEA), with which patients were classified into low- or high-risk groups. Pathway enrichment results revealed enrichment in the cytokine-cytokine receptor interaction, metabolism of xenobiotics by cytochrome P450, and viral protein interaction with cytokine and cytokine receptor pathways. Most of the enriched pathways are metabolic pathways predominantly enriched by downregulated genes, suggesting numerous downregulated metabolic pathways in the high-risk group. Subsequent tumor immune infiltration analysis indicated that neutrophil infiltration, resting CD4 memory T cells, and resting natural killer (NK) cells correlated with the risk score. After verifying that the seven gene expression levels in different KRAS-mutated pancreatic cancer cell lines were similar to that in the model, we screened potential drugs related to the risk score.Discussion: This study established, analyzed, and validated a model for predicting the prognosis of PDAC based on risk stratification according to KRAS mutations, and identified differential pathways and highly effective drugs.

The novel COVID-19 pneumonia caused by the SARS-CoV-2 virus poses a significant threat to human health. Scientists have made significant efforts to control this virus, consequently leading to the development of novel research methods. Traditional animal and 2D cell line models might not be suitable for large-scale applications in SARS-CoV-2 research owing to their limitations. As an emerging modelling method, organoids have been applied in the study of various diseases. Their advantages include their ability to closely mirror human physiology, ease of cultivation, low cost, and high reliability; thus, they are considered to be a suitable choice to further the research on SARS-CoV-2. During the course of various studies, SARS-CoV-2 was shown to infect a variety of organoid models, exhibiting changes similar to those observed in humans. This review summarises the various organoid models used in SARS-CoV-2 research, revealing the molecular mechanisms of viral infection and exploring the drug screening tests and vaccine research that have relied on organoid models, hence illustrating the role of organoids in remodelling SARS-CoV-2 research.

R-loop is a special DNA-RNA hybrid genomic structure. Since its identification, the molecular mechanisms of physiological processes such as class switch recombination have been revealed, uncontrolled regulation of which has become the underlying cause of many diseases. With the development of molecular biology techniques, R-loops found at different sites and formed via different mechanisms have been discovered. These non-classical R-loops participate in various cellular activities via different mechanisms. A set of sophisticated regulatory mechanisms are required to control the number of various R-loops in vivo. The levels of non-classical R-loops in tumor cells differ significantly from those in normal cells; in addition, the regulatory mechanisms for establishing R-loop homeostasis differ, which may be utilized to develop breakthrough therapies for various tumors. In this review, we summarize the current state of knowledge regarding non-classical R-loops in tumor cells, the mechanisms that promote or inhibit this structure, the effects of this structure on tumor cells, and the possible therapeutic targets. By systematically elucidating the pathogenic mechanisms of atypical R-loops, we can achieve precision targeting of tumors and revolutionize clinical precision oncology.