Characteristics of Early Gastric Cancer in a Patient with a History of Helicobacter pylori Infection and No History of Eradication Therapy.

Objective The characteristics of gastric cancer in patients with atrophic mucosa and no apparent history of Helicobacter pylori eradication have not been thoroughly investigated. Therefore, this study examined the clinicopathological characteristics of gastric cancer in these patients. Methods We retrospectively examined the endoscopic and pathological characteristics of gastric cancer in patients who underwent endoscopic submucosal dissection. Patients or Materials We divided the patients into 2 groups: those with gastric atrophy and no history of eradication (group A; n =102) and those with a history of eradication (group B; n =161). In group A, patients were further divided into mild atrophy (group C) and severe atrophy (group D) groups, while group B was further divided into those who underwent eradication treatment >5 years ago (group E) and those who underwent eradication 1-5 years ago (group F). Results Group A comprised significantly older individuals (75±8.0 vs. 71±7.5 years old, p <0.001) with a higher frequency of elevated gastric cancer than group B (32.4% vs. 17.4%, p =0.006). Compared with group E, group A was older and had a greater incidence of elevated gastric cancer. The incidence of gastric cancer in the U or M region was lower in group C than in group D. Conclusion Gastric cancer in patients with gastric atrophy and no history of eradication was associated with an older age and higher frequency of elevated-type morphology than in those with a history of eradication.

Initial clinical experience with durvalumab plus tremelimumab in patients with unresectable hepatocellular carcinoma in real­world practice.

Although durvalumab plus tremelimumab (Dur/Tre) has been approved as first-line therapy for patients with unresectable hepatocellular carcinoma (u-HCC), its outcomes in real-world clinical practice are unclear. The present study aimed to evaluate the efficacy and safety of Dur/Tre treatment. This multicenter study was conducted between March 2023 and January 2024, and included 120 patients with u-HCC treated with Dur/Tre. Among the patients, 44 had no history of systemic treatment. Progression-free survival (PFS), therapeutic response and adverse events (AEs) were assessed. The objective response rate (ORR) and disease control rates (DCR) were 15.8 and 53.3%, respectively. The median PFS was 3.9 months. The incidence rates of AEs of any grade and those grade 3 or higher were 83.3 and 36.7%, respectively. Liver injury was the most frequent AE of any grade and grade 3 or higher. Although there was no significant difference in ORR and PFS between the first and later line groups (ORR 15.8 vs. 15.7%, P=0.986; PFS 4.5 vs. 3.6 months, P=0.213), there was a significant difference in DCR between the two groups (65.8 vs. 45.9%, P=0.034). No significant differences were noted between the first- and later-line treatment groups regarding the incidence rate of AEs. Decision tree analysis revealed that poor liver function and advanced age were significant variables for discontinuation owing to AEs. In conclusion, Dur/Tre as first-line therapy had better disease control responses compared with later-line therapy; however, this regimen should be carefully administered to patients with deteriorating hepatic function or advanced age.

Recent updates on treatment options for primary follicular lymphoma of the gastrointestinal tract.

BACKGROUND: Primary gastrointestinal follicular lymphoma is a subtype of follicular lymphoma that originates directly from the gastrointestinal tract. Pathologically, it exhibits substantial similarities with the secondary gastrointestinal involvement observed in nodal follicular lymphoma. However, primary gastrointestinal follicular lymphoma presents clinically distinct features, necessitating divergent considerations in treatment selection compared with nodal follicular lymphoma. AREAS COVERED: This narrative review focused on recent articles (2018-2023) regarding the long-term prognosis and treatment options for gastrointestinal follicular lymphoma. In addition, a brief overview of gastrointestinal follicular lymphomas is provided. EXPERT OPINION: Patients with primary gastrointestinal follicular lymphoma often present with a low tumor burden. Lymphoma lesions typically remain asymptomatic for several years or may undergo spontaneous regression without immediate treatment. Therefore, a 'watch and wait' approach is justified. Conversely, when large tumor masses are identified in the gastrointestinal tract, the potential for tumor bleeding or intestinal obstruction requires timely therapeutic interventions.

PTBP1 protects Y RNA from cleavage leading to its apoptosis-specific degradation.

Some RNAs such as 28S rRNA, U1 small nuclear RNA (snRNA), and Y RNAs are known to be cleaved during apoptosis. The underlying mechanism, functions, and biological significance of RNA degradation in apoptosis remain elusive. Y RNAs are non-coding RNAs widely conserved from bacteria to mammals, and are major components of Ro ribonucleoprotein (RNP) complexes which contain the 60 kDa Ro protein (SS-A) and the 50 kDa La protein (SS-B). The autoantigenic Ro and La proteins were identified by autoantibodies present in the sera from patients with Systemic lupus erythematosus (SLE) and Sjögren's syndrome (SjS). We previously identified novel, functional small RNAs named AGO-taxis small RNAs (ASRs) that are specifically bound to Argonaute protein 1 (AGO1), which are processed from Y RNAs. Cell-free analysis combined with fractionation methods revealed that the apoptosis-specific biogenesis of ASRs or cleavage of Y RNA was induced by truncation of polypyrimidine tract-binding protein 1 (PTBP1), which is an endoribonuclease inhibitor of Y RNAs by caspase 3. Caspase 3-resistant PTBP1 mutant protected cleavage of Y RNAs in apoptosis induced by staurosporine. Furthermore, caspase 3-resistant PTBP1 mutant knock-in mice showed elevated cytokines, dysregulation of the germinal center formation compared to the wild-type mice at LPS stimulation, and high positivity of antinuclear antibody. Those results suggest that cleavage of Y RNAs or biogenesis of ASR during apoptosis has critical biological functions and their deregulation result in immune dysregulation and the formation of autoantibody, possibly leading to the development of autoimmune diseases.

Virtual indigo carmine chromoendoscopy images: A novel modality for peroral cholangioscopy using artificial intelligence technology (with video).

BACKGROUND AND AIMS: Accurately diagnosing biliary strictures is crucial for surgical decisions, and although peroral cholangioscopy (POCS) aids in visual diagnosis, diagnosing malignancies or determining lesion margins via this route remains challenging. Indigo carmine is commonly used to evaluate lesions during gastrointestinal endoscopy. We aimed to establish the utility of virtual indigo carmine chromoendoscopy (VICI) converted from POCS images using artificial intelligence. METHODS: This single-center, retrospective study analyzed 40 patients with biliary strictures who underwent POCS using white light imaging (WLI) and narrow-band imaging (NBI). A "cycle-consistent adversarial network" (CycleGAN) was used to convert the WLI into VICI of POCS images. Three experienced endoscopists evaluated WLI, NBI, and VICI via POCS in all patients. The primary outcome was the visualization quality of surface structures, surface microvessels, and lesion margins. The secondary outcome was diagnostic accuracy. RESULTS: VICI showed superior visualization of the surface structures and lesion margins compared with WLI (P<0.001) and NBI (P<0.001). The diagnostic accuracies were 72.5%, 87.5%, and 90.0% in WLI alone, WLI and VICI simultaneously, and WLI and NBI simultaneously, respectively. WLI and VICI simultaneously tended to result in higher accuracy than WLI alone (P=0.083) and the results were not significantly different from WLI and NBI simultaneously (P=0.65). CONCLUSIONS: VICI in POCS proved valuable for visualizing surface structures and lesion margins and contributed to higher diagnostic accuracy comparable to NBI. In addition to NBI, VICI may be a novel supportive modality for POCS.

Impact of Nutritional Status on Neutrophil-to-Lymphocyte Ratio as a Predictor of Efficacy and Adverse Events of Immune Check-Point Inhibitors.

The neutrophil -to-lymphocyte ratio (NLR) is useful for predicting the effectiveness of treatment with immune checkpoint inhibitors (ICIs) and immune-related adverse events (irAEs). Because a growing body of evidence has recently shown that the number of lymphocytes that comprise NLR fluctuates according to nutritional status, this study examined whether the usefulness of NLR varies in ICI treatment due to changes in nutritional status. A retrospective analysis was performed on 1234 patients who received ICI treatment for malignant tumors at our hospital. Progression-free survival (PFS) was significantly prolonged in patients with NLR < 4. Multivariate analysis revealed that the factors associated with the occurrence of irAE were NLR < 4 and the use of ipilimumab. However, when limited to cases with serum albumin levels <3.8 g/dL, lymphocyte counts significantly decreased, and the associations between NLR and PFS and between NLR and irAE occurrence disappeared. In contrast, when limited to the cases with serum albumin levels ≥3.8 g/dL, the associations remained, with significantly prolonged PFS and significantly increased irAE occurrence at NLR < 4. NLR may be a good predictive tool for PFS and irAE occurrence during ICI treatment when a good nutritional status is maintained.

Drug-induced mucosal alterations observed during esophagogastroduodenoscopy.

Several features of drug-induced mucosal alterations have been observed in the upper gastrointestinal tract, i.e., the esophagus, stomach, and duodenum. These include pill-induced esophagitis, desquamative esophagitis, worsening of gastroesophageal reflux, chemotherapy-induced esophagitis, proton pump inhibitor-induced gastric mucosal changes, medication-induced gastric erosions and ulcers, pseudomelanosis of the stomach, olmesartan-related gastric mucosal inflammation, lanthanum deposition in the stomach, zinc acetate hydrate tablet-induced gastric ulcer, immune-related adverse event gastritis, olmesartan-asso-ciated sprue-like enteropathy, pseudomelanosis of the duodenum, and lanthanum deposition in the duodenum. For endoscopists, acquiring accurate knowledge regarding these diverse drug-induced mucosal alterations is crucial not only for the correct diagnosis of these lesions but also for differential diag-nosis of other conditions. This minireview aims to provide essential information on drug-induced mucosal alterations observed on esophagogastroduodenoscopy, along with representative endoscopic images.

Current status of endoscopic ultrasound-guided antitumor treatment for pancreatic cancer.

Endoscopic ultrasound (EUS) was developed in the 1990s and has significantly transformed pancreatic tumor diagnosis. Subsequently, EUS has rapidly shifted from being a purely diagnostic procedure to being used in a wide range of interventional procedures. Recently, new therapeutic techniques, such as EUS-guided fine needle injection (EUS-FNI) or radiofrequency ablation (RFA), have been developed to deliver various antitumor agents. Despite technological advancements, pancreatic cancer (PC) has a poor prognosis and improvements in treatment outcomes are urgently required. One of the reasons for the limited response to antitumor agents in PC is the abundant desmoplasia and hypovascular nature of the tumor, complicating drug delivery into the tumor. Thus, changing the tumor microenvironment may be important to enhance the effectiveness of chemotherapy, and direct injection of antitumor agents into the tumor under EUS guidance can help overcome treatment challenges in PC. Treatment approaches using the EUS-FNI or RFA technique are expected to further improve the prognosis of PC. Therefore, this study reviewed the existing literature on EUS-guided antitumor therapy, specifically highlighting its application in PC to address the current challenges and to identify potential advancements in the field.

MicroRNA-34a-5p: A pivotal therapeutic target in gallbladder cancer.

Gallbladder cancer incidence has been increasing globally, and it remains challenging to expect long prognosis with the current systemic chemotherapy. We identified a novel nucleic acid-mediated therapeutic target against gallbladder cancer by using innovative organoid-based gallbladder cancer models generated from KrasLSL-G12D/+; Trp53f/f mice. Using comprehensive microRNA expression analyses and a bioinformatics approach, we identified significant microRNA-34a-5p downregulation in both murine gallbladder cancer organoids and resected human gallbladder cancer specimens. In three different human gallbladder cancer cell lines, forced microRNA-34a-5p expression inhibited cell proliferation and induced cell-cycle arrest at the G1 phase by suppressing direct target (CDK6) expression. Furthermore, comprehensive RNA sequencing revealed the significant enrichment of gene sets related to the cell-cycle regulators after microRNA-34a-5p expression in gallbladder cancer cells. In a murine xenograft model, locally injected microRNA-34a-5p mimics significantly inhibited gallbladder cancer progression and downregulated CDK6 expression. These results provide a rationale for promising therapeutics against gallbladder cancer by microRNA-34a-5p injection, as well as a strategy to explore therapeutic targets against cancers using organoid-based models, especially for those lacking useful genetically engineered murine models, such as gallbladder cancer.

Endoscopic manifestation of intestinal transplant-associated microangiopathy after stem cell transplantation.

BACKGROUND: Endoscopic features of intestinal transplant-associated microangiopathy (iTAM) have not been comprehensively investigated. This study aimed to examine the endoscopic characteristics of patients diagnosed with iTAM. METHODS: This retrospective analysis included 14 patients pathologically diagnosed with iTAM after stem cell transplantation for hematolymphoid neoplasms (n = 13) or thalassemia (n = 1). The sex, age at diagnosis, endoscopic features, and prognosis of each patient were assessed. Serological markers for diagnosing transplant-associated thrombotic microangiopathy were also evaluated. RESULTS: The mean age at the time of iTAM diagnosis was 40.2 years. Patients diagnosed based on the pathognomonic pathological changes of iTAM presented with diverse symptoms at the times of endoscopic examinations, including diarrhea (n = 10), abdominal pain (n = 5), nausea (n = 4), appetite loss (n = 2), bloody stools (n = 2), abdominal discomfort (n = 1), and vomiting (n = 1). At the final follow-up, six patients survived, while eight patients succumbed, with a median time of 100.5 days (range: 52-247) post-diagnosis. Endoscopic manifestations included erythematous mucosa (n = 14), erosions (n = 13), ulcers (n = 9), mucosal edema (n = 9), granular mucosa (n = 9), and villous atrophy (n = 4). Erosions and/or ulcers were primarily observed in the colon (10/14, 71%), followed by the ileum (9/13, 69%), stomach (4/10, 40%), cecum (5/14, 36%), duodenum (3/10, 30%), rectum (4/14, 29%), and esophagus (1/10, 10%). Cytomegalovirus infection (n = 4) and graft-versus-host disease (n = 2) coexisted within the gastrointestinal tract. Patients had de novo prolonged or progressive thrombocytopenia (6/14, 43%), decreased hemoglobin concentration (4/14, 29%), reduced serum haptoglobin level (3/14, 21%), and a sudden and persistent increase in lactate dehydrogenase level (2/14, 14%). Peripheral blood samples from 12 patients were evaluated for schistocytes, with none exceeding 4%. CONCLUSIONS: This study provides a comprehensive exploration of the endoscopic characteristics of iTAM. Notably, all patients exhibited erythematous mucosa throughout the gastrointestinal tract, accompanied by prevalent manifestations, such as erosions (93%), ulcers (64%), mucosal edema (64%), granular mucosa (64%), and villous atrophy (29%). Because of the low positivity for serological markers of transplant-associated thrombotic microangiopathy in patients with iTAM, endoscopic evaluation and biopsy of these lesions are crucial, even in the absence of these serological features.

Detection of residual stones by peroral direct cholangioscopy in patients with intrahepatic stones after hepaticojejunostomy: a prospective study (with video).

BACKGROUND AND AIMS: The difficulty in radiographic confirmation of the presence of stones remains challenging in the treatment of intrahepatic bile duct (IHBD) stones in patients after hepaticojejunostomy (HJ). Peroral direct cholangioscopy (PDCS) enables direct observation of the bile duct and is useful for detecting and removing residual stones; however, its effectiveness is not clearly established in this clinical context. METHODS: This single-center, single-arm, prospective study included 44 patients with IHBD who underwent bowel reconstruction with HJ during the study period. Stone removal was performed by using short-type double-balloon enteroscopy. After balloon-occluded cholangiography, the double-balloon enteroscopy was exchanged for an ultra-slim endoscope through the balloon overtube for PDCS. The primary end point was the rate of residual stones detected by PDCS. Secondary end points were success rate of PDCS, residual stone removal with PDCS, procedure time for PDCS, procedure-related adverse events, and stone recurrence rate. RESULTS: PDCS was successful in 39 (89%) of 44 patients, among whom residual stones were detected in 16 (41%) (95% CI, 28%-54%). Twelve patients (75%) had residual stones <5 mm. Stone removal was successful in 15 (94%) patients, and median procedure time for PDCS was 16 minutes (interquartile range, 10-26 minutes). The rate of procedure-related adverse events was 7% (3 of 44); all adverse events improved with conservative treatment. During the median follow-up of 2.1 years (interquartile range, 1.4-3.3 years), the overall probability of recurrence-free status at 1, 2, and 3 years was 100%, 92%, and 86%, respectively. CONCLUSIONS: PDCS is a safe and effective procedure for complete stone removal in patients with IHBD stones after HJ.

Predictive factors for transition to conversion therapy in hepatocellular carcinoma using atezolizumab plus bevacizumab.

BACKGROUND: To identify predictive factors associated with successful transition to conversion therapy following combination therapy with atezolizumab and bevacizumab in the treatment of unresectable hepatocellular carcinoma (HCC). METHODS: In total, 188 patients with HCC, who received atezolizumab plus bevacizumab combination therapy as the first-line chemotherapy, were studied. Patients who achieved complete response (CR) with systemic chemotherapy alone were excluded. Clinical factors possibly linked to successful transition to conversion therapy and the achievement of cancer-free status were identified. RESULTS: Fifteen (8.0%) patients underwent conversion therapy. In the conversion group, there was a significantly higher proportion of patients with Barcelona Clinic Liver Cancer (BCLC) stage A or B (73.3% versus [vs.] 45.1%; p = .03) and tended to have lower Child-Pugh scores and alpha-fetoprotein levels. Multivariate analysis revealed that BCLC stage was a predictive factor for the implementation of conversion therapy (A or B; odds ratio 3.7 [95% CI: 1.1-13]; p = .04). Furthermore, 10 (66.7%) patients achieved cancer-free status and exhibited a smaller number of intrahepatic lesions at the start of treatment (3.5 vs. 7; p < .01), and a shorter interval between systemic chemotherapy induction and conversion therapy (131 vs. 404 days; p < .01). In addition, the rate of achieving cancer-free status by undergoing surgical resection or ablation therapy was significantly higher (p = .03). CONCLUSION: BCLC stage was the sole predictive factor for successful transition to conversion therapy when using combination therapy with atezolizumab and bevacizumab to treat HCC. Furthermore, a small number of intrahepatic lesions and early transition to conversion therapy were associated with the achievement of cancer-free status.

Risk factors and treatment strategies for cholecystitis after metallic stent placement for malignant biliary obstruction: a multicenter retrospective study.

BACKGROUND AND AIMS: Cholecystitis can occur after self-expandable metallic stent (SEMS) placement for malignant biliary obstruction (MBO), but the best treatment option for cholecystitis has not been determined. Here, we aimed to identify the risk factors of cholecystitis after SEMS placement and determine the best treatment option. METHODS: Incidence, treatments, and predictive factors of cholecystitis were retrospectively evaluated in 1084 patients with distal MBO (DMBO) and 353 patients with hilar MBO (HMBO) who underwent SEMS placement at 12 institutions from January 2012 to March 2021. RESULTS: Cholecystitis occurred in 7.5% of patients with DMBO and 5.9% of patients with HMBO. The recurrence rate was significantly lower (P = .043) and the recurrence-free period significantly longer (P = .039) in endoscopic procedures than in percutaneous procedures for cholecystitis treatment. EUS-guided gallbladder drainage (EUS-GBD) was better in terms of technical success, procedure time, and recurrence-free period than endoscopic transpapillary gallbladder drainage. Obstruction across the cystic duct orifice by tumor (P = .015) and by stent (P = .037) were independent risk factors for cholecystitis in DMBO. Cases with multiple SEMS placements (odds ratio [OR], 11; 95% confidence interval [CI], 0.68-190; P = .091) and with gallbladder stones (OR, 2.3; 95% CI ,0.92-5.6; P = .075) had a higher risk for cholecystitis in HMBO. CONCLUSIONS: The incidences of cholecystitis after SEMS placement for DMBO and HMBO were similar. EUS-GBD is the optimal treatment option for patients with cholecystitis after SEMS placement for MBO.

Methylation analysis of DCC gene in saliva samples is an efficient method for non-invasive detection of superficial hypopharyngeal cancer.

BACKGROUND: Advances in upper gastrointestinal endoscopic technology have enabled early detection and treatment of hypopharyngeal cancer. However, in-depth pharyngeal observations require sedation and are invasive. It is important to establish a minimally invasive and simple evaluation method to identify high-risk patients. METHODS: Eighty-seven patients with superficial hypopharyngeal cancer and 51 healthy controls were recruited. We assessed the methylation status of DCC, PTGDR1, EDNRB, and ECAD, in tissue and saliva samples and verified the diagnostic accuracy by methylation analyses of their promoter regions using quantitative methylation-specific PCR. RESULTS: Significant differences between cancer and their surrounding non-cancerous tissues were observed in the methylation values of DCC (p = 0.003), EDNRB (p = 0.001), and ECAD (p = 0.043). Using receiver operating characteristic analyses of the methylation values in saliva samples, DCC showed the highest area under the curve values for the detection of superficial hypopharyngeal cancer (0.917, 95% confidence interval = 0.864-0.970), compared with those for EDNRB (0.680) and ECAD (0.639). When the cutoff for the methylation values of DCC was set at ≥0.163, the sensitivity to detect hypopharyngeal cancer was 82.8% and the specificity was 90.2%. CONCLUSIONS: DCC methylation in saliva samples could be a non-invasive and efficient tool for early detection of hypopharyngeal cancer in high-risk patients.

Long-term monitoring of gastric mucosa-associated lymphoid tissue lymphoma in patients with extra copies of the MALT1 gene.

The objective of this study was to clarify the long-term prognosis of patients with gastric mucosa-associated lymphoid tissue (MALT) lymphoma with additional copies of MALT1. In this multicenter retrospective study, we enrolled 145 patients with gastric MALT lymphoma who underwent fluorescence in situ hybridization (FISH) analysis to detect t(11;18) translocation. The patient cohort was divided into three groups: Group A (n = 87), comprising individuals devoid of the t(11;18) translocation or extra MALT1 copies; Group B (n = 27), encompassing patients characterized by the presence of the t(11;18) translocation; and Group C (n = 31), including patients with extra MALT1 copies. The clinical outcomes in each cohort were collected. Over the course of a mean follow-up of 8.5 ± 4.2 years, one patient died of progressive MALT lymphoma, while 15 patients died due to etiologies unrelated to lymphoma. The progression or relapse of MALT lymphoma was observed in 11 patients: three in Group A, two in Group B, and six in Group C. In Groups A, B, and C, the 10-year overall survival rates were 82.5%, 93.8%, and 86.4%, respectively, and the 10-year event-free survival rates were 96.1%, 96.0%, and 82.9%, respectively. The event-free survival rate in Group C was significantly lower than that in Group A. However, no differences were observed in the 10-year event-free survival rates among individuals limited to stage I or II1 disease (equivalent to excluding patients with stage IV disease in this study, as there were no patients with stage II2), with rates of 98.6%, 95.8%, and 92.3% for Groups A, B, and C, respectively. In conclusion, the presence of extra copies of MALT1 was identified as an inferior prognostic determinant of event-free survival. Consequently, trisomy/tetrasomy 18 may serve as an indicator of progression and refractoriness to therapeutic intervention in patients with gastric MALT lymphoma, particularly stage IV gastric MALT lymphoma.

Satellite double-stranded RNA induces mesenchymal transition in pancreatic cancer by regulating alternative splicing.

Human satellite II (HSATII), composed of tandem repeats in pericentromeric regions, is aberrantly transcribed in epithelial cancers, particularly pancreatic cancer. Dysregulation of repetitive elements in cancer tissues can facilitate incidental dsRNA formation; however, it remains controversial whether dsRNAs play tumor-promoting or tumor-suppressing roles during cancer progression. Therefore, we focused on the double-stranded formation of HSATII RNA and explored its molecular function. The overexpression of double-stranded HSATII (dsHSATII) RNA promoted mesenchymal-like morphological changes and enhanced the invasiveness of pancreatic cancer cells. We identified an RNA-binding protein, spermatid perinuclear RNA-binding protein (STRBP), which preferentially binds to dsHSATII RNA rather than single-stranded HSATII RNA. The mesenchymal transition of dsHSATII-expressing cells was rescued by STRBP overexpression. Mechanistically, STRBP is involved in the alternative splicing of genes associated with epithelial-mesenchymal transition (EMT). We also confirmed that isoform switching of CLSTN1, driven by dsHSATII overexpression or STRBP depletion, induced EMT-like morphological changes. These findings reveal a novel tumor-promoting function of dsHSATII RNA, inducing EMT-like changes and cell invasiveness, thus enhancing our understanding of the biological significance of aberrant expression of satellite arrays in malignant tumors.

Gut Bacteria-derived Membrane Vesicles Induce Colonic Dysplasia by Inducing DNA Damage in Colon Epithelial Cells.

BACKGROUND & AIMS: Colorectal cancer (CRC) is the third most common cancer in the world. Gut microbiota has recently been implicated in the development of CRC. Actinomyces odontolyticus is one of the most abundant bacteria in the gut of patients with very early stages of CRC. A odontolyticus is an anaerobic bacterium existing principally in the oral cavity, similar to Fusobacterium nucleatum, which is known as a colon carcinogenic bacterium. Here we newly determined the biological functions of A odontolyticus on colonic oncogenesis. METHODS: We examined the induction of intracellular signaling by A odontolyticus in human colonic epithelial cells (CECs). DNA damage levels in CECs were confirmed using the human induced pluripotent stem cell-derived gut organoid model and mouse colon tissues in vivo. RESULTS: A odontolyticus secretes membrane vesicles (MVs), which induce nuclear factor kappa B signaling and also produce excessive reactive oxygen species (ROS) in colon epithelial cells. We found that A odontolyticus secretes lipoteichoic acid-rich MVs, promoting inflammatory signaling via TLR2. Simultaneously, those MVs are internalized into the colon epithelial cells, co-localize with the mitochondria, and cause mitochondrial dysfunction, resulting in excessive ROS production and DNA damage. Induction of excessive DNA damage in colonic cells by A odontolyticus-derived MVs was confirmed in the gut organoid model and also in mouse colon tissues. CONCLUSIONS: A odontolyticus secretes MVs, which cause chronic inflammation and ROS production in colonic epithelial cells, leading to the initiation of CRC.