BACKGROUND Appendectomy reduces the occurrence and controls the severity of ulcerative colitis (UC); however, how it exerts these effects remains unclear. AIM To elucidate the contribution of appendix-associated immune responses in intestinal inflammation and their relevance to the effects of appendectomy in UC. METHODS This study was conducted at Graduate School of Medicine, The University of Osaka. We included patients undergoing surgery for UC and those without inflammatory bowel disease undergoing colorectal cancer surgery as controls. Appendiceal tissues were collected from both patient groups, and macroscopically normal appendices located at least 10 cm from the tumor were used as controls. Single-cell RNA sequencing, immunohistochemistry, and flow cytometry were performed. RESULTS Single-cell RNA sequencing identified T, B, plasma, innate lymphoid, and mast cells, together with other myeloid cells in appendiceal tissues. A hallmark feature of the appendices in UC was an increase in immunoglobulin G (IgG)-expressing plasma cells. Immunohistochemistry revealed significantly reduced IgG levels in the large intestines of patients with UC who had undergone an appendectomy compared with levels in those who did not undergo appendectomy. Repertoire analysis revealed an increased production of IgG antibodies bearing an integrin-binding motif at antigen-recognition sites in patients with UC. CONCLUSION The appendix is a major site of pathogenic IgG antibody production in patients with UC, providing the immunological basis for appendectomy as a treatment for UC.

SDC4 is a member of the syndecan protein family, and its expression is upregulated in various cancers, including gastrointestinal adenocarcinomas. Although SDC4 is reportedly associated with poor prognosis, tumor growth, and metastasis, the regulatory mechanism of SDC4 gene expression in cancer cells is poorly understood. In the present study, we performed database analysis and found that the SDC4 promoter region includes several potential binding sites for the KLF5 transcription factor. Promoter assay in colorectal cancer cell line further demonstrated that two potential KLF5 protein-binding regions located near positions -70 to -40 on the SDC4 promoter are particularly critical for promoter activity. ChIP-qPCR analysis confirmed that KLF5 protein bound to this region, suggesting strong involvement of KLF5 protein. Additionally, immunohistochemical staining of human tissues revealed that SDC4 and KLF5 exhibited similar expression patterns in some colorectal cancer cases, and detected a significant positive correlation between SDC4 and KLF5 expressions. Overall, these results suggest that SDC4 expression is regulated by KLF5 at the colorectal cancer tissue level, and in cultured cell lines. In conclusion, we have newly identified SDC4 as a target gene of the KLF5 transcription factor.

Cancer‑associated fibroblasts (CAFs) play critical roles in the tumor microenvironment (TME); however, their characteristics under hypoxic conditions remain incompletely understood. The aim of the present study was to investigate the properties of hypoxic CAFs and identify their regulatory factors in colorectal cancer (CRC). CAFs cultured under normoxic and hypoxic conditions were analyzed using proliferation assays, co‑culture experiments, shotgun proteomics and single‑cell RNA sequencing. Clinical specimens were evaluated immunohistochemically using the desmoplastic reaction (DR) classification. In addition, the generalizability of the findings was validated by correlation analyses using The Cancer Genome Atlas database. Hypoxic CAFs showed enhanced proliferative capacity, and their conditioned medium promoted migration and chemoresistance in CRC cells. Shotgun proteomics revealed a significant increase in vitamin D‑binding protein in the conditioned media of hypoxic CAFs, while single‑cell RNA sequencing showed enrichment of genes related to bone metabolism and the phosphoinositide 3‑kinase‑AKT signaling pathway. Treatment of normal fibroblasts (NFs) with parathyroid hormone‑related protein (PTHrP) induced CAF‑like phenotypes, whereas treatment of CAFs with vitamin D led to morphological changes toward a NF‑like appearance. In clinical samples, the immature DR subtype, associated with poor prognosis, exhibited increased expression of the hypoxia marker hypoxia‑inducible factor‑1α, periostin and PTHrP, along with a significant association with Kirsten rat sarcoma viral oncogene homolog (KRAS) mutations. Furthermore, a strong positive correlation was observed between the copy numbers of PTHrP and KRAS across multiple cancer types, including CRC. These findings suggest that the PTHrP‑vitamin D‑rat sarcoma oncogene (RAS) axis functions as an important regulatory mechanism in hypoxic CAFs. PTHrP and vitamin D may influence each other's activity, and this axis may contribute to tumor progression within the TME. Therefore, the PTHrP‑vitamin D‑RAS axis could serve as a potential therapeutic target.

Locally recurrent rectal cancer (LRRC) occurs in 6–10

Transmembrane protein 161 A (TMEM161A), also known as adaptive response to oxidative stress-29, has been implicated in cellular stress responses, but its role in colorectal cancer (CRC) remains unclear. Here, we investigated the clinical relevance and functional significance of TMEM161A in CRC, using integrated clinical, experimental, and transcriptomic analyses. Immunohistochemical analysis of 133 surgically resected CRC specimens showed that high TMEM161A expression was associated with worse survival outcomes in our institutional cohort. Functional assays using siRNA-mediated TMEM161A knockdown demonstrated marked suppression of malignant phenotypes, including proliferation, migration, invasion, and a stemness-related phenotype. Transcriptomic profiling coupled with gene set enrichment analysis revealed that TMEM161A silencing downregulated cell cycle- and growth-related pathways while activating stress response and checkpoint signaling programs. Collectively, these findings support a role for TMEM161A in malignant behavior in CRC and suggest that TMEM161A may serve as a prognostic biomarker candidate and a potential therapeutic target, linking tumor growth with cellular stress responses.

INTRODUCTION: Achieving margin-negative complete resection in locally recurrent rectal cancer often requires en bloc resection involving adjacent structures such as the sacrum. However, sacrectomy is technically demanding and poses a high risk of significant intraoperative bleeding and postoperative pelvic sepsis due to the dead space created after resection. We developed a minimally invasive surgical technique to address these challenges. TECHNIQUE: We used a laparoscopic approach to sacrectomy as part of en bloc resection for posterior locally recurrent rectal cancer. In this technique, the anterior and lateral dissection of the sacrum was performed laparoscopically, whereas the final sacral transection was performed under direct vision in the prone position. Preoperative imaging was used to identify the planned sacral transection line, which was reproduced intraoperatively using a premeasured vascular tape. Anterior and lateral dissection of the sacrum was performed laparoscopically to allow secure vascular control. Final sacral transection was performed under direct vision in the prone position. A pedicled omental flap and a dead-space-filling nonfunctional anastomosis were used to fill the pelvic cavity and prevent postoperative sepsis. A double-barreled stoma was created to facilitate fecal diversion. RESULTS: Laparoscopic sacrectomy was successfully performed in 43 patients with locally recurrent rectal cancer. The margin-negative complete resection rate was 86%, which is notably high for this challenging population. The 5-year overall survival rate was approximately 59%. No cases of major intraoperative bleeding or early complications related to the dead-space-filling nonfunctional anastomosis were observed. CONCLUSIONS: This laparoscopic technique offers a safe and feasible option for selected patients with posterior locally recurrent rectal cancer. Combined dead-space management may further help reduce postoperative complications while preserving oncological validity.

Background/Aim: Pancreatic cancer remains one of the most lethal malignancies, with limited therapeutic options and an extremely poor prognosis. MicroRNAs (miRNAs), which regulate gene expression at the post-transcriptional level, have emerged as promising candidates for next-generation cancer therapeutics. The purpose of this study is to clarify the feasibility of miR-4711 as a potential therapeutic option against pancreatic cancer. Materials and Methods: The effects of miR-4711-5p were examined in pancreatic cancer cell lines with respect to cell proliferation, apoptosis, cancer stemness, cell cycle progression, and invasive capacity. RNA sequencing and in silico analyses were performed to identify potential target genes of miR-4711-5p. For in vivo safety evaluation, miR-4711-5p was formulated with super carbonate apatite, a delivery vehicle that is already amenable to large-scale production, and administered to cynomolgus monkeys. A nucleic acid dose equivalent to 10 times the effective dose observed in prior mouse efficacy studies was used. General clinical conditions, body weight, food consumption, ophthalmologic findings, electrocardiography, blood pressure, hematological and biochemical parameters, and histopathological changes were systematically assessed. Results: miR-4711-5p significantly suppressed cancer stemness, cell proliferation, and invasion, while inducing apoptosis and delaying cell cycle progression in pancreatic cancer cells. RNA sequencing and bioinformatic analyses identified MET, CTSA, and ANO1 as potential target genes of miR-4711-5p. In the cynomolgus monkey study, administration of miR-4711-5p formulated with super carbonate apatite resulted in no apparent differences compared with the control group in body weight, clinical observations, laboratory parameters, or histopathological findings, indicating the absence of treatment-related adverse effects even at a supra-therapeutic dose. Conclusions: These findings demonstrate that miR-4711-5p exerts potent antitumor effects against pancreatic cancer cells while exhibiting a favorable safety profile in a non-human primate model. Collectively, this study provides strong preclinical evidence supporting miR-4711-5p as a novel and safe therapeutic strategy for pancreatic cancer and represents an important step toward clinical application.

ABSTRACT Crohn's disease (CD) has traditionally been explained by an “inside‐out” model, in which disruption of the intestinal mucosal barrier allows luminal bacteria to invade the bowel wall and trigger transmural inflammation. This concept has supported therapeutic strategies that emphasize mucosal healing. However, accumulating pathological and anatomical evidence suggests that the earliest abnormalities in CD may arise outside the mucosa, particularly within the mesenteric lymphatic system. In this review, we reconsider the pathogenesis of CD and propose an alternative “outside‐in” model, in which intestinal inflammation is initiated by mesenteric and subserosal lymphatic dysfunction. Histopathological studies have demonstrated that lymphatic vessel dilation, obstruction, and granulomatous inflammation frequently occur in the subserosal layer along the mesenteric border, even in macroscopically normal intestinal segments. These findings suggest that mucosal lesions are secondary changes following lymphatic injury. The segmented architecture of intestinal lymphatic drainage also explains the characteristic skip lesions of CD, as localized lymphatic dysfunction can generate regionally confined inflammation. Genetic susceptibility pathways related to bacterial recognition, autophagy, and lymphangiogenesis intersect with lymphatic endothelial biology, promoting lymphatic stasis and immune activation. Mesenteric adipose tissue, particularly creeping fat, further amplifies inflammation through immunometabolic interactions with lymphatic vessels and immune cells. Collectively, these observations support the concept that mesenteric lymphatic dysfunction plays a central role in initiating and sustaining CD. The proposed outside‐in model provides an integrated framework that links lymphatic injury, transmural inflammation, and mesenteric pathology and highlights the mesenteric lymphatic system as a potential therapeutic target in CD.

BACKGROUND:Despite recent advances in chemotherapy for colorectal cancer (CRC), chemotherapy-sensitive tumours often develop resistance to treatment, which remains a major clinical challenge. This acquired chemoresistance limits the efficacy of subsequent therapies and is associated with a poor prognosis. Therefore, this study identified the mechanisms of acquired chemoresistance in CRC and developed innovative targeted therapies. METHODS:5-fluorouracil (5-FU)-and oxaliplatin (OX)-resistant CRC cells were established through long-term exposure to anticancer drugs, and RNA sequencing (RNA-seq) was performed. RNA-seq data integrated analysis from resistant cells and public single-cell RNA-seq datasets from clinical CRC samples was conducted to identify key drivers of chemoresistance. Prognostic significance was evaluated by immunohistochemical analysis of liver metastasis specimens from patients with CRC who underwent curative resection of the primary tumours. RESULTS:Chemotherapy exposure enriched high stemness and activated TGF-β signalling. GDF15 was identified as a key molecule upregulated in both chemoresistant and high-stemness cells. Clinically, high GDF15 expression is associated with early recurrence and poor prognosis. Functional assays demonstrated that GDF15 overexpression promoted chemoresistance, stemness, and migratory capacity of CRC cells. CONCLUSIONS:GDF15 promotes chemoresistance in CRC by promoting stem cell-like properties. These findings provide insights into therapeutic strategies for overcoming acquired chemoresistance and improving outcomes.

BACKGROUND/AIM:Management of inflammatory bowel disease-associated gastrointestinal cancers, including Crohn's disease-associated cancer and ulcerative colitis-associated cancer, remains challenging because of concerns regarding treatment-related toxicity and limited clinical data. We aimed to investigate the safety of chemotherapy in patients with inflammatory bowel disease-associated gastrointestinal cancer. PATIENTS AND METHODS:This retrospective study analyzed 21 patients with inflammatory bowel disease-associated gastrointestinal cancer (Crohn's disease-associated cancer: 10; ulcerative colitis-associated cancer: 11) who received chemotherapy or chemoradiotherapy between 2010 and 2024. Chemotherapy regimens, adverse events, treatment completion rates, and residual small intestinal lengths in patients with Crohn's disease were evaluated. RESULTS:Oxaliplatin-based chemotherapy was the most commonly used chemotherapeutic regimen. Dose reduction was required in all patients with Crohn's disease-associated cancer and in 64% of those with ulcerative colitis-associated cancer, primarily because of diarrhea or neurotoxicity. In the Crohn's disease-associated cancer group, diarrhea occurred in all patients and was significantly more severe in those with shorter residual small intestines (p=0.02). Despite these toxicities, 80% of patients with Crohn's disease-associated cancer and 55% of those with ulcerative colitis-associated cancer completed the planned chemotherapy regimen. No inflammatory bowel disease flares or need for corticosteroids or biologics occurred during treatment. Chemoradiotherapy was administered to five patients with Crohn's disease-associated cancer and locally advanced anorectal cancer, with no major safety concerns. CONCLUSION:Chemotherapy, including chemoradiotherapy, can be safely administered to patients with inflammatory bowel disease-associated gastrointestinal cancer with careful management. In Crohn's disease-associated cancer, residual small intestinal length is a key factor in predicting gastrointestinal toxicity severity, particularly diarrhea. Individualized dose adjustments and close monitoring are essential to balance cancer treatment efficacy with the unique risks associated with inflammatory bowel disease.

BACKGROUND:Switch/sucrose nonfermentable (SWI/SNF) complexes regulate gene expression through chromatin remodeling and include a recently reported subtype non-canonical BAF (ncBAF). The BRD9 gene that plays a central role in forming ncBAF has been reported to be a poor prognostic factor for various carcinomas. However, the role of BRD9 in colorectal cancer (CRC) has rarely been explored. METHODS:In this study, resected specimens acquired from 124 patients who underwent colorectal resection at our institution between January 2013 and December 2013 were immuno-stained and analyzed. RESULTS:The BRD9 high-expression groups exhibited poor prognoses in terms of overall and disease-free survival rates; moreover, high expression was identified as an independent prognostic factor via multivariate analysis. The BRD9 knockdown predominantly decreased the migration and proliferation abilities in the human CRC cell line compared with in the negative controls. RNA sequencing suggested the potential association of BRD9 with 13 genes, including CCN1. In a mouse subcutaneous tumor model, the BRD9 knockdown significantly reduced tumorigenesis compared with that in the negative control. CONCLUSIONS:These results indicate that BRD9 is an independent poor prognostic factor in CRC and is involved in tumor proliferation, migration, and tumorigenicity through the CCN1-mediated enhancement of cancer cell malignancy.

Visceral obesity and malnutrition are each associated with poor prognosis in gastrointestinal cancers. This study investigates the impact of undernutrition combined with visceral obesity on perioperative complications in laparoscopic colorectal cancer surgery. We retrospectively analyzed 223 colorectal cancer patients who underwent curative laparoscopic resection at our institution between January 2010 and December 2011. Undernutrition was defined as the Geriatric Nutritional Risk Index (GNRI), calculated using the ideal body weight ratio and serum albumin level, with GNRI < 107 indicating undernutrition. Visceral obesity was defined as a visceral fat area (VFA) >100 cm2 at the umbilical level. Patients were divided into two groups: those with both undernutrition and visceral obesity (n=40) and others (n=183). Associations with perioperative complications were analyzed, along with background factors including age, gender, BMI, albumin (Alb), CRP, tumor markers, and other nutritional indices. Additionally, a new nutritional status score for predicting postoperative complications was developed using ROC curve analysis based on easily measurable indicators from blood tests, CT scans, and physical exams. The malnutrition and visceral obesity group showed a significantly higher incidence of Grade 2 or higher perioperative complications compared to the other group (25.0% vs. 10.9%; p = 0.037). Analysis of nutritional and oncological indicators identified age, BMI, VFA, CRP, lymphocyte count, and CA19-9 as associated with postoperative complications. A novel nutritional status score incorporating these factors predicted Grade 2 or higher complications with a sensitivity of 43.0% and a specificity of 83.3%. Undernutrition combined with visceral obesity significantly increased the risk of perioperative complications. Preoperative nutritional interventions to improve patient status may reduce these risks and should be further investigated. Kengo Haruna, Norikatsu Miyoshi, Shiki Fujino, Rie Mizumoto, Rie Hayashi, Mitsunobu Takeda, Yuki Sekido, Tsuyoshi Hata, Atsushi Hamabe, Takayuki Ogino, Mamoru Uemura, Hirofumi Yamamoto, Yuichiro Doki, Hidetoshi Eguchi. Association between visceral fat obesity and perioperative complications of undernutrition in laparoscopic surgery for colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 2112.

Cancer treatment is increasingly based on precision medicine, which tailors therapies to the genetic and biological characteristics of a patient's tumor. PDOs offer a promising platform for predicting drug sensitivity, helping to identify effective therapies. However, existing models still face limitations in replicating clinical tumor heterogeneity and predicting drug responses accurately. In this study, we developed a novel two-dimensional (2D) culture system (2DO) for CRC PDOs that improves reproducibility and better mirrors the tumor microenvironment compared to traditional methods. The goal of this study is to evaluate the effectiveness of PDO-based drug sensitivity assays in predicting clinical outcomes for CRC patients. We aim to explore the potential of PDO assays in personalized treatment strategies, improving CRC treatment outcomes. Tumor samples from CRC patients were obtained via surgery or endoscopic biopsy. These tumors were washed, dissociated, and filtered to isolate viable tumor cells, which were then cultured as PDOs under optimized conditions that preserve the tumor’s genetic and phenotypic characteristics. Drug sensitivity assays were performed by treating PDOs with different chemotherapeutic agents and measuring cell proliferation using a method: the Incucyte system (SARTRIUS, Germany) for live-cell imaging. Drug sensitivity assays using PDOs showed promising results. The Incucyte system had a positive predictive value (PPV) of 75% and a negative predictive value (NPV) of 33% when compared to clinical outcomes. This result suggests that PDOs are useful for predicting tumor response to chemotherapy, though improving the NPV is necessary for more reliable predictions. The combination of imaging and biochemical assays offered a comprehensive evaluation of drug effects, and the PDOs closely mimicked patient-specific treatment responses. This study demonstrates the potential of PDO-based drug sensitivity assays as a tool for personalized treatment in colorectal cancer. While promising, further refinement is needed, particularly in improving the negative predictive value, to optimize PDO models for clinical use. PDO-based assays may help bridge the gap between laboratory findings and real-world therapeutic outcomes, contributing to more individualized cancer treatments in the future. Rie Hayashi, Norikatsu Miyoshi, Rie Mizumoto, Kengo Haruna, Shiki Fujino, Mitsunobu Takeda, Yuki Sekido, Tsuyoshi Hata, Atsushi Hamabe, Takayuki Ogino, Mamoru Uemura, Yuichiro Doki, Hidetoshi Eguchi. A study on prediction model of drug sensitivity using patient-derived organoids [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 1699.

BACKGROUND/AIM:Neoadjuvant chemoradiotherapy (CRT) is the standard treatment for locally advanced rectal adenocarcinoma, the optimal regimen remains unknown. For squamous cell carcinoma (SCC), 5-fluorouracil (5-FU) plus mitomycin C (MMC) with radiotherapy (RT) is commonly used; however, alternative medicines are needed for patients unable to receive MMC or those avoiding prolonged infusion. The combination of S-1 and oxaliplatin (SOX) with RT has been explored for rectal and anal cancer, but its efficacy and safety remain uncertain. This study retrospectively evaluated SOX + RT outcomes. PATIENTS AND METHODS:This single-center retrospective study analyzed 20 patients with anorectal adenocarcinoma and squamous cell carcinoma who received SOX + RT at Osaka University Hospital between March 2012 and June 2024. SOX+RT was administered as neoadjuvant or curative treatment. Tumor regression and adverse events were assessed per standard grading criteria. Survival analysis was performed using the Kaplan-Meier method. RESULTS:Among 20 evaluable cases, 14 were adenocarcinomas and 6 were SCCs. Twelve patients received the treatment as neoadjuvant therapy, while eight underwent it with curative intent. The local response rate was 60%, with all SCC cases achieving complete response. R0 resection was achieved in 83%, and anal preservation in 88%. The 3-year progression-free survival (PFS) rate was 39.2%, and overall survival (OS) was 70.6%, with SCC showing better PFS (80.0%) than adenocarcinoma (28.6%). Grade 3 adverse events occurred in 50%, but no treatment-related deaths were reported. CONCLUSION:SOX + RT was safe and effective, particularly for SCC, suggesting its potential as an alternative when standard therapy is not feasible.