DNA methyltransferase CHROMOMETHYLASE3 prevents ONSEN transposon silencing under heat stress.

DNA methylation plays crucial roles in transposon silencing and genome integrity. CHROMOMETHYLASE3 (CMT3) is a plant-specific DNA methyltransferase responsible for catalyzing DNA methylation at the CHG (H = A, T, C) context. Here, we identified a positive role of CMT3 in heat-induced activation of retrotransposon ONSEN. We found that the full transcription of ONSEN under heat stress requires CMT3. Interestingly, loss-of-function CMT3 mutation led to increased CHH methylation at ONSEN. The CHH methylation is mediated by CMT2, as evidenced by greatly reduced CHH methylation in cmt2 and cmt2 cmt3 mutants coupled with increased ONSEN transcription. Furthermore, we found more CMT2 binding at ONSEN chromatin in cmt3 compared to wild-type accompanied with an ectopic accumulation of H3K9me2 under heat stress, suggesting a collaborative role of H3K9me2 and CHH methylation in preventing heat-induced ONSEN activation. In summary, this study identifies a non-canonical role of CMT3 in preventing transposon silencing and provides new insights into how DNA methyltransferases regulate transcription under stress conditions.

Delayed perforation after cold snare polypectomy for small colonic polyps in a patient receiving oral corticosteroids.

This case report describes a fatal outcome due to delayed perforation after cold snare polypectomy in a patient with bullous pemphigoid receiving oral corticosteroids. Cold snare polypectomy has become the standard treatment for small colorectal polyps because of the procedure's safety and simplicity. In this case, however, corticosteroid therapy and vasculitis may have caused local necrosis and tearing of the intestinal wall. Corticosteroids are widely used, and perforation after cold snare polypectomy is extremely rare. However, some patients on corticosteroid therapy may have special pathologies, such as in this case, and we advise physicians to use appropriate judgment and extreme caution in determining the indication for endoscopic therapy.

Digital PCR-based plasma cell-free DNA mutation analysis for early-stage pancreatic tumor diagnosis and surveillance.

BACKGROUND: Cell-free DNA (cfDNA) shed from tumors into the circulation offers a tool for cancer detection. Here, we evaluated the feasibility of cfDNA measurement and utility of digital PCR (dPCR)-based assays, which reduce subsampling error, for diagnosing pancreatic ductal adenocarcinoma (PDA) and surveillance of intraductal papillary mucinous neoplasm (IPMN). METHODS: We collected plasma from seven institutions for cfDNA measurements. Hot-spot mutations in KRAS and GNAS in the cfDNA from patients with PDA (n = 96), undergoing surveillance for IPMN (n = 112), and normal controls (n = 76) were evaluated using pre-amplification dPCR. RESULTS: Upon Qubit measurement and copy number assessment of hemoglobin-subunit (HBB) and mitochondrially encoded NADH:ubiquinone oxidoreductase core subunit 1 (MT-ND1) in plasma cfDNA, HBB offered the best resolution between patients with PDA relative to healthy subjects [area under the curve (AUC) 0.862], whereas MT-ND1 revealed significant differences between IPMN and controls (AUC 0.851). DPCR utilizing pre-amplification cfDNA afforded accurate tumor-derived mutant KRAS detection in plasma in resectable PDA (AUC 0.861-0.876) and improved post-resection recurrence prediction [hazard ratio (HR) 3.179, 95% confidence interval (CI) 1.025-9.859] over that for the marker CA19-9 (HR 1.464; 95% CI 0.674-3.181). Capturing KRAS and GNAS could also provide genetic evidence in patients with IPMN-associated PDA and undergoing pancreatic surveillance. CONCLUSIONS: Plasma cfDNA quantification by distinct measurements is useful to predict tumor burden. Through appropriate methods, dPCR-mediated mutation detection in patients with localized PDA and IPMN likely to progress to invasive carcinoma is feasible and complements conventional biomarkers.

Utility of "liquid biopsy" using pancreatic juice for early detection of pancreatic cancer.

Background Despite advances in the diagnosis of pancreatic ductal adenocarcinoma (PDA), histological evaluation of small and poorly defined masses in the pancreas is uncomfortable and unsafe. Methods We herein report a case of early stage PDA, in which multiple KRAS mutations were detected in the pancreatic juice preoperatively. A small hypoechoic area adjacent to the portal vein was detected through endoscopic ultrasound in the pancreatic body. KRAS mutations were evaluated using plasma, and the pancreatic juice by digital PCR. Results Pancreatic duct biopsy and pancreatic juice cytology were performed with no evidence of malignancy; however, KRAS mutations, KRAS G12V and G12D, were detected in the pancreatic juice. Histological assessment of the resected specimen demonstrated a solid tumor with desmoplastic reaction accompanied by carcinoma in situ in the main pancreatic duct where KRAS G12V mutation was identified. More detailed analysis demonstrated KRAS G12D mutation in the cluster of low grade pancreatic intraepithelial neoplasia, implying that the lesion developed independently. Conclusions Our study indicates the potential of "endoscopic liquid biopsy" to capture the driver gene for PDA diagnosis.

Primary Poorly Differentiated Squamous Cell Carcinoma of the Extrahepatic Bile Duct.

Squamous cell carcinoma of the extrahepatic bile duct is quite rare. A 77-year-old woman with jaundice and general fatigue was referred to our hospital. Multiphase contrast-enhanced computed tomography visualized a 17-mm solid mass in the junction of the cystic and common bile ducts. The patient underwent pylorus-preserving pancreaticoduodenectomy. The pathological findings demonstrated keratin-positive poorly differentiated squamous cell carcinoma of the extrahepatic bile duct (T3N0M0, stage IIIA). Although adjuvant chemotherapy with gemcitabine was administered, the patient exhibited local recurrence at the site of anastomosis of biliojejunostomy 20 months after resection and died 32 months after resection.

A randomized, double-blinded, placebo-controlled, multicenter trial, healing effect of rebamipide in patients with low-dose aspirin and/or non-steroidal anti-inflammatory drug induced small bowel injury.

BACKGROUND: It is not clear what kind of drug is appropriate to heal NSAID-induced enteropathy. Several reports showed the preventive effect of prostaglandin analogue or inducer using healthy subjects who took NSAIDs. However there was no report for healing effect and for patients. The aim of this study was to evaluate the healing effect of rebamipide in patients with NSAIDs-induced enteropathy. In addition, we evaluated for nutritional parameter. METHODS: This study was conducted as a randomized, double-blinded, placebo-controlled, multicenter trial. Study protocol was approved by each hospital's ethical committees. Patients with LDA and/or NSAID more than 3 months were enrolled. Patients with enteropathy were divided into the placebo and the rebamipide groups. Rebamipide 100 mg three times daily was administered during 4 weeks. Capsule endoscopies were performed at 0 and 4 week. The number of small intestinal ulcer and erosion were evaluated. Total protein was analyzed as nutritional parameter. RESULTS: Sixty one participants were completed this study. Change in number of small intestinal erosion in the rebamipide group was -2.5 ± 3.4, and 2.1 ± 3.9 in the placebo group (P < 0.0001). Change in number of small intestinal ulcer in the rebamipide group was -0.5 ± 1.6, and 0.1 ± 0.7 in the placebo group (P = 0.024). Change in serum total protein levels in the rebamipide group was 0.06 ± 0.36, and -0.27 ± 0.34 in the placebo group (P = 0.0005). CONCLUSIONS: Rebamipide has not only the healing effect for NSAIDs-induced enteropathy compared with placebo, but the improvement of nutritional condition. These results showed a tentative therapeutical strategy for chronic NSAIDs users.

Small intestinal intussusceptions due to the placement of a percutaneous endoscopic jejunostomy tube.

Percutaneous endoscopic jejunostomy (PEJ) has been developed and is considered to be a better method than percutaneous endoscopic gastrostomy for preventing the occurrence of aspiration pneumonia. However, the incidence of other complications associated with this procedure is less clear. We herein report a rare case with a small intestinal intussusception due to a PEJ placement. In this case, a radiologic examination with gastrografin was useful to detect the typical findings of a small intestinal intussusception, a beak-like filling defect, and identify the location of the lesion. An endoscopic examination that was carefully performed with a thin scope was effective to observe the ischaemic change of the small intestine and immediately determine the indication for surgical treatment. This case highlights the necessity to carefully manage patients with a PEJ placement, considering the risk of small intestinal intussusceptions when the patient complains of symptoms that are suspicious for an intestinal obstruction.