Explore the vast range of titles available.

Metaplastic breast cancer (MpBC) is an exceedingly rare breast cancer variant that is therapeutically challenging and aggressive. MpBC is defined by the histological presence of at least two cellular types, typically epithelial and mesenchymal components. This variant harbors a triple-negative breast cancer (TNBC) phenotype, yet has a worse prognosis and decreased survival compared to TNBC. There are currently no standardized treatment guidelines specifically for MpBC. However, prior studies have found that MpBC typically has molecular alterations in epithelial-to-mesenchymal transition, amplification of epidermal growth factor receptor, PI3K/Akt signaling, nitric oxide signaling, Wnt/β-catenin signaling, altered immune response, and cell cycle dysregulation. Some of these molecular alterations have been studied as therapeutic targets, in both the preclinical and clinical setting. This current review discusses the histological organization and cellular origins of MpBC, molecular alterations, the role of radiation therapy, and current clinical trials for MpBC.

Key Points Metaplasia is the replacement of one differentiated cell type with another mature differentiated cell type that is not normally present in that tissue. Metaplasia, when persistent, can be a precursor to dysplasia, which can in turn progress to carcinoma. As a result, recognition of metaplasia through screening and surveillance modalities is important and could reveal potential strategies for both cancer prevention and therapy. Metaplasia is an adaptive response to injurious agents, which are largely environmental in nature (for example, acid, bile, cigarette smoke and alcohol), but is also influenced by the actions of microorganisms (for example, Helicobacter pylori and human papillomavirus (HPV)). Different types of metaplasia exist, depending upon the tissue source: squamous, intestinal and acinar–ductal. The cell of origin has been postulated to be from the gastric cardia in oesophageal intestinal metaplasia and to be triggered by loss of parietal cells in gastric intestinal metaplasia. Metaplastic cell-autonomous (for example, mutant KRAS signalling) and non-cell-autonomous mechanisms contribute to the development and maintenance of metaplasia. Metaplasia, the replacement of one differentiated somatic cell type with another in the same tissue, is a precursor to dysplasia and eventually carcinoma. There are shared principles across different types of tissue metaplasia that may be helpful in clinical considerations. Metaplasia is the replacement of one differentiated somatic cell type with another differentiated somatic cell type in the same tissue. Typically, metaplasia is triggered by environmental stimuli, which may act in concert with the deleterious effects of microorganisms and inflammation. The cell of origin for intestinal metaplasia in the oesophagus and stomach and for pancreatic acinar–ductal metaplasia has been posited through genetic mouse models and lineage tracing but has not been identified in other types of metaplasia, such as squamous metaplasia. A hallmark of metaplasia is a change in cellular identity, and this process can be regulated by transcription factors that initiate and/or maintain cellular identity, perhaps in concert with epigenetic reprogramming. Universally, metaplasia is a precursor to low-grade dysplasia, which can culminate in high-grade dysplasia and carcinoma. Improved clinical screening for and surveillance of metaplasia might lead to better prevention or early detection of dysplasia and cancer.

Metaplastic breast carcinoma (MBC) is a highly aggressive form of triple-negative cancer (TNBC), defined by the presence of metaplastic components of spindle, squamous, or sarcomatoid histology. The protein profiles underpinning the pathological subtypes and metastatic behavior of MBC are unknown. Using multiplex quantitative tandem mass tag-based proteomics we quantify 5798 proteins in MBC, TNBC, and normal breast from 27 patients. Comparing MBC and TNBC protein profiles we show MBC-specific increases related to epithelial-to-mesenchymal transition and extracellular matrix, and reduced metabolic pathways. MBC subtypes exhibit distinct upregulated profiles, including translation and ribosomal events in spindle, inflammation- and apical junction-related proteins in squamous, and extracellular matrix proteins in sarcomatoid subtypes. Comparison of the proteomes of human spindle MBC with mouse spindle ( CCN6 knockout) MBC tumors reveals a shared spindle-specific signature of 17 upregulated proteins involved in translation and 19 downregulated proteins with roles in cell metabolism. These data identify potential subtype specific MBC biomarkers and therapeutic targets. Metaplastic breast carcinoma (MBC) is among the most aggressive subtypes of triple-negative breast cancer (TNBC) but the underlying proteome profiles are unknown. Here, the authors characterize the protein signatures of human MBC tissue samples and their relationship to TNBC and normal breast tissue.

BackgroundGastric intestinal metaplasia (GIM), particularly the incomplete subtype (Inc IM), is strongly associated with increased gastric cancer (GC) risk. However, its role as a true precursor lesion remains uncertain.ObjectiveWe aimed to delineate the molecular identity, differentiation potential and oncogenic relevance of Inc IM.MethodsSpatial transcriptomics using a custom lineage-enriched panel was applied to profile GIM and GC tissues. Subtype-specific GIM organoid models were developed for DNA methylation and chromatin accessibility profiling. Single-cell RNA sequencing was performed to evaluate differentiation capacity.ResultsSpatial transcriptomics revealed that Inc IM potentially originates from the deep antral gland cells and harbours a hybrid transcriptomic signature incorporating gastric, small intestinal and large intestinal lineages across both differentiated and stem/progenitor compartments. DNA methylation profiling of subtype-specific organoids showed that Inc IM exhibits extensive intergenic hypermethylation, resembling native antral mucosa. In contrast, complete subtype was marked by promoter hypermethylation of tumour suppressor genes and displayed a more fully intestinalised epigenetic profile. Organoid models recapitulated subtype-specific traits and demonstrated lineage plasticity. Spatial mapping of GC samples revealed an enrichment of Inc IM-like cells, particularly within microsatellite stable tumours. Approximately 76% of the GCs analysed were linked to GIM, while the remaining (24%) appeared to be associated with deep antral differentiation.ConclusionsInc IM represents a phenotypically unstable and epigenetically deregulated metaplastic state with dual-lineage potential and molecular resemblance to GC. These findings establish Inc IM as a true precursor to GC and underscore the importance of active surveillance and early intervention strategies.

The landscapes of somatic mutation in normal cells inform us about the processes of mutation and selection operative throughout life, providing insight into normal ageing and the earliest stages of cancer development 1 . Here, by whole-genome sequencing of 238 microdissections 2 from 30 individuals, including 18 with gastric cancer, we elucidate the developmental trajectories of normal and malignant gastric epithelium. We find that gastric glands are units of monoclonal cell populations that accrue roughly 28 somatic single-nucleotide variants per year, predominantly attributable to endogenous mutational processes. In individuals with gastric cancer, metaplastic glands often show elevated mutation burdens due to acceleration of mutational processes linked to proliferation and oxidative damage. Unusually for normal cells, gastric epithelial cells often carry recurrent trisomies of specific chromosomes, which are highly enriched in a subset of individuals. Surveying 829 polyclonal gastric microbiopsies by targeted sequencing, we find somatic ‘driver’ mutations in a distinctive repertoire of known cancer genes, including ARID1A , ARID1B , ARID2 , CTNNB1 and KDM6A . The prevalence of mutant clones increases with age to occupy roughly 8% of the gastric epithelial lining by age 60 years and is significantly increased by the presence of severe chronic inflammation. Our findings provide insights into intrinsic and extrinsic influences on somatic evolution in the gastric epithelium in healthy, precancerous and malignant states. Whole-gene sequencing of microdissected gastric glands from individuals with and without gastric cancer reveals distinct patterns of somatic mutations and provides insights into influences on the somatic evolution of the gastric epithelium.

BackgroundGastric intestinal metaplasia (IM) is a precancerous stage spanning a morphological spectrum that is poorly represented by human cell line models.ObjectiveWe aim to establish and characterise human IM cell models to better understand IM progression along the cancer spectrum.DesignA large human gastric IM organoid (IMO) cohort (n=28), their clonal derivatives and normal gastric organoids (n=42) for comparison were established. Comprehensive multi-omics profiling and functional characterisation were performed.ResultsSingle-cell transcriptomes revealed IMO cells spanning a spectrum from hybrid gastric/intestinal to advanced intestinal differentiation. Their lineage trajectories connected different cycling and quiescent stem and progenitors, highlighting differences in gastric to IM transition and the potential origin of IM from STMN1 cycling isthmus stem cells. Hybrid IMOs showed impaired differentiation potential, high lineage plasticity beyond gastric or intestinal fates and reactivation of a fetal gene programme.Cell populations in gastric IM and cancer tissues were highly similar to those derived from IMOs and exhibited a fetal signature. Genomically, IMOs showed elevated mutation burden, frequent chromosome 20 gain and epigenetic deregulation of many intestinal and gastric genes. Functionally, IMOs were FGF10 independent and showed downregulated FGFR2. Several IMOs exhibited a cell-matrix adhesion independent subpopulation that displayed chromosome 20 gain but lacked key cancer driver mutations, potentially representing the earliest neoplastic precursor of IM-induced gastric cancer.ConclusionsOverall, our IMO biobank captured the heterogeneous nature of IM, revealing mechanistic insights on IM pathogenesis and progression, offering an ideal platform for studying early gastric neoplastic transformation and chemoprevention.

ObjectiveThe presence of intestinal metaplasia (IM) is a risk factor for gastric cancer. However, it is still controversial whether IM itself is precancerous or paracancerous. Here, we aimed to explore the precancerous nature of IM by analysing epigenetic alterations.DesignGenome-wide DNA methylation analysis was conducted by EPIC BeadArray using IM crypts isolated by Alcian blue staining. Chromatin immunoprecipitation sequencing for H3K27ac and single-cell assay for transposase-accessible chromatin by sequencing were conducted using IM mucosa. NOS2 was induced using Tet-on gene expression system in normal cells.ResultsIM crypts had a methylation profile unique from non-IM crypts, showing extensive DNA hypermethylation in promoter CpG islands, including those of tumour-suppressor genes. Also, the IM-specific methylation profile, namely epigenetic footprint, was present in a fraction of gastric cancers with a higher frequency than expected, and suggested to be associated with good overall survival. IM organoids had remarkably high NOS2 expression, and NOS2 induction in normal cells led to accelerated induction of aberrant DNA methylation, namely epigenetic instability, by increasing DNA methyltransferase activity. IM mucosa showed dynamic enhancer reprogramming, including the regions involved in higher NOS2 expression. NOS2 had open chromatin in IM cells but not in gastric cells, and IM cells had frequent closed chromatin of tumour-suppressor genes, indicating their methylation-silencing. NOS2 expression in IM-derived organoids was upregulated by interleukin-17A, a cytokine secreted by extracellular bacterial infection.ConclusionsIM cells were considered to have a precancerous nature potentially with an increased chance of converting into cancer cells, and an accelerated DNA methylation induction due to abnormal NOS2 expression.

BackgroundWhile p53 mutations occur early in Barrett’s oesophagus (BE) progression to oesophageal adenocarcinoma (EAC), their role in gastric cardia stem cells remains unclear.ObjectiveThis study investigates the impact of p53 mutation on the fate and function of cardia progenitor cells in BE to EAC progression, particularly under the duress of chronic injury.DesignWe used a BE mouse model (L2-IL1β) harbouring a Trp53 mutation (R172H) to study the effects of p53 on Cck2r+ cardia progenitor cells. We employed lineage tracing, pathological analysis, organoid cultures, single-cell RNA sequencing (scRNA-seq) and computational analyses to investigate changes in progenitor cell behaviour, differentiation patterns and tumour progression. Additionally, we performed orthotopic transplantation of sorted metaplastic and mutant progenitor cells to assess their tumourigenic potential in vivo.ResultsThe p53 mutation acts as a switch to expand progenitor cells and inhibit their differentiation towards metaplasia, but only amidst chronic injury. In L2-IL1β mice, p53 mutation increased progenitors expansion and lineage-tracing with a shift from metaplasia to dysplasia. scRNA-seq revealed dysplastic cells arise directly from mutant progenitors rather than progressing through metaplasia. In vitro, p53 mutation enhanced BE progenitors’ organoid-forming efficiency, growth, DNA damage resistance and progression to aneuploidy. Sorted metaplastic cells grew poorly with no progression to dysplasia, while mutant progenitors gave rise to dysplasia in orthotopic transplantation. Computational analyses indicated that p53 mutation inhibited stem cell differentiation through Notch activation.Conclusionsp53 mutation contributes to BE progression by increasing expansion and fitness of undifferentiated cardia progenitors and preventing their differentiation towards metaplasia.

Background Intestinal metaplasia (IM) is classified into complete intestinal metaplasia (CIM) and incomplete intestinal metaplasia (IIM). Patients diagnosed with IIM face an elevated susceptibility to the development of gastric cancer, underscoring the critical need for early screening measures. In addition to the complexities associated with diagnosis, the exact mechanisms driving the progression of gastric cancer in IIM patients remain poorly understood. OLFM4 is overexpressed in several types of tumors, including colorectal, gastric, pancreatic, and ovarian cancers, and its expression has been associated with tumor progression. Methods In this study, we used pathological sections from two clinical centers, biopsies of IM tissues, precancerous lesions of gastric cancer (PLGC) cell models, animal models, and organoids to explore the role of OLFM4 in IIM. Results Our results show that OLFM4 expression is highly increased in IIM, with superior diagnostic accuracy of IIM when compared to CDX2 and MUC2. OLFM4, along with MYH9, was overexpressed in IM organoids and PLGC animal models. Furthermore, OLFM4, in combination with Myosin heavy chain 9 (MYH9), accelerated the ubiquitination of GSK3β and resulted in increased β-catenin levels through the Wnt signaling pathway, promoting the proliferation and invasion abilities of PLGC cells. Conclusions OLFM4 represents a novel biomarker for IIM and could be utilized as an important auxiliary means to delimit the key population for early gastric cancer screening. Finally, our study identifies cell signaling pathways involved in the progression of IM.

Gastric cancer (GC) is primarily associated with Helicobacter pylori ( H. pylori ) infection, which disrupts gastric mucosa homeostasis, leading to epithelial-mesenchymal transition (EMT) and intestinal metaplasia (IM). We previously found that ELMO1 methylation increased with the progression of chronic gastric inflammation, and its expression was significantly elevated in GC tissues. Further analysis indicated that ELMO1 methylation may interact with Med31. This paper aims to determine the molecular mechanism of ELMO1 methylation in H. pylori -infected GC. The viability, proliferation, and migration of H. pylori -infected AGS cells were detected by cell counting kit-8 (CCK-8), wound healing, and colony information assay, respectively. The methylation status of ELMO1 was determined by methylation-specific PCR (MSP) analysis. mRNA expression levels were detected by quantitative reverse transcription polymerase chain reaction (qRT-PCR). Western blotting and enzyme-linked immunosorbent assay (ELISA) were used to evaluate protein levels. Co-immunoprecipitation was used to detect proteins interacting with ELMO1 . Co-culture experiments were performed to explore the mechanism of ELMO1 methylation in regulating M2 polarization and IM in H. pylori -infected AGS cells. ELMO1 methylation was significantly upregulated in AGS cells upon H. pylori infection. Our data suggest that ELMO1 methylation accelerated H. pylori -induced IM in AGSs by interacting with Med31. Additionally, we found that ELMO1 methylation drives M2 polarization in H. pylori -infected GCs through interaction with Med31. Further study indicated that ELMO1 methylation enhances H. pylori -induced EMT and IM by promoting M2 polarization. This study suggests that ELMO1 methylation interacts with Med31 and activates M2 macrophage polarization s to facilitate EMT and IM in GC with H. pylori infection.