Simultaneous activation of Kras-Akt and Notch pathways induces extrahepatic biliary cancer via the mTORC1 pathway.

Biliary tract cancer (BTC) has poor prognosis. The Notch receptor is aberrantly expressed in extrahepatic cholangiocarcinoma (eCCA). However, the role of Notch signaling in the initiation and progression of eCCA and gallbladder (GB) cancer remains unknown. Therefore, we investigated the functional role of Notch signaling during tumorigenesis of the extrahepatic bile duct (EHBD) and GB. Activation of Notch signaling and oncogenic Kras resulted in the development of biliary intraepithelial neoplasia (BilINs) in the EHBD and GB, which were premalignant lesions that progressed to adenocarcinoma in mice. The expression of genes involved in the mTORC1 pathway was increased in biliary spheroids from Hnf1b-CreERT2; KrasLSL-G12D ; Rosa26LSL-NotchIC mice and inhibition of the mTORC1 pathway suppressed spheroid growth. Additionally, simultaneous activation of the PI3K-AKT and Notch pathways in EHBD and GB induced biliary cancer development in mice. Consistent with this, we observed a significant correlation between activated NOTCH1 and phosphorylated Ribosomal Protein S6 (p-S6) expression in human eCCA. Furthermore, inhibition of the mTORC1 pathway suppressed the growth of Notch-activated human biliary cancer cells in vitro and in vivo. Mechanistically, the Kras/Notch-Myc axis activated mTORC1 through TSC2 phosphorylation in mutant biliary spheroids. These data indicate that inhibition of the mTORC1 pathway could be an effective treatment strategy for Notch-activated human eCCA. © 2023 The Pathological Society of Great Britain and Ireland.

The role of the SWI/SNF chromatin remodeling complex in pancreatic ductal adenocarcinoma.

ATP-dependent chromatin remodeling complexes are a group of epigenetic regulators that can alter the assembly of nucleosomes and regulate the accessibility of transcription factors to DNA in order to modulate gene expression. One of these complexes, the SWI/SNF chromatin remodeling complex is mutated in more than 20% of human cancers. We have investigated the roles of the SWI/SNF complex in pancreatic ductal adenocarcinoma (PDA), which is the most lethal type of cancer. Here, we reviewed the recent literature regarding the role of the SWI/SNF complex in pancreatic tumorigenesis and current knowledge about therapeutic strategies targeting the SWI/SNF complex in PDA. The subunits of the SWI/SNF complex are mutated in 14% of human PDA. Recent studies have shown that they have context-dependent oncogenic or tumor-suppressive roles in pancreatic carcinogenesis. To target its tumor-suppressive properties, synthetic lethal strategies have recently been developed. In addition, their oncogenic properties could be novel therapeutic targets. The SWI/SNF subunits are potential therapeutic targets for PDA, and further understanding of the precise role of the SWI/SNF complex subunits in PDA is required for further development of novel strategies targeting SWI/SNF subunits against PDA.

Tumor invasion to the arteries feeding the gallbladder as a novel risk factor for cholecystitis after metallic stent placement in distal malignant biliary obstruction.

BACKGROUND AND AIM: Cholecystitis is a major complication after self-expandable metallic stent (SEMS) placement for malignant biliary obstruction. Ischemia is one of the risk factors for cholecystitis, but little is known about the influence of tumor invasion to the feeding artery of the gallbladder on the onset of cholecystitis after SEMS placement. The aim of the present study was to identify risk factors for cholecystitis after SEMS placement. METHODS: Incidence and nine predictive factors of cholecystitis were retrospectively evaluated in 107 patients who underwent SEMS placement for unresectable distal malignant biliary obstruction at Kyoto University Hospital and Otsu Red Cross Hospital between January 2012 and June 2016. RESULTS: Cholecystitis occurred in 13 of 107 patients (12.1%) after SEMS placement during the median follow-up period of 262 days. Univariate analyses showed that tumor invasion to the feeding artery of the gallbladder and tumor involvement to the orifice of the cystic duct were significant predictors of cholecystitis (P = 0.001 and P < 0.001). Multivariate analysis confirmed that these two factors were significant and independent risks for cholecystitis with odds ratios of 22.13 (95% CI, 3.57-137.18; P = 0.001) and 25.26 (95% CI, 4.12-154.98; P < 0.001), respectively. CONCLUSIONS: This study showed for the first time that tumor invasion to the feeding artery of the gallbladder as well as tumor involvement to the orifice of the cystic duct are independent risk factors for cholecystitis after SEMS placement.

THBS1-producing tumor-infiltrating monocyte-like cells contribute to immunosuppression and metastasis in colorectal cancer.

Mesenchymal activation, characterized by dense stromal infiltration of immune and mesenchymal cells, fuels the aggressiveness of colorectal cancers (CRC), driving progression and metastasis. Targetable molecules in the tumor microenvironment (TME) need to be identified to improve the outcome in CRC patients with this aggressive phenotype. This study reports a positive link between high thrombospondin-1 (THBS1) expression and mesenchymal characteristics, immunosuppression, and unfavorable CRC prognosis. Bone marrow-derived monocyte-like cells recruited by CXCL12 are the primary source of THBS1, which contributes to the development of metastasis by inducing cytotoxic T-cell exhaustion and impairing vascularization. Furthermore, in orthotopically generated CRC models in male mice, THBS1 loss in the TME renders tumors partially sensitive to immune checkpoint inhibitors and anti-cancer drugs. Our study establishes THBS1 as a potential biomarker for identifying mesenchymal CRC and as a critical suppressor of antitumor immunity that contributes to the progression of this malignancy with a poor prognosis.

Pyoderma gangrenosum with primary sclerosing cholangitis-associated colitis successfully treated with concomitant granulocyte and monocyte adsorption apheresis with corticosteroids.

An 18-year-old woman was admitted to our hospital with fever, diarrhea and painful skin ulcers in both pretibial areas starting 19 days earlier. The skin lesions appeared deep necrotic ulcers with violaceous undermined borders. She had been diagnosed as ulcerative colitis and primary sclerosing cholangitis (PSC) 6 and 5 years before, respectively, and had stopped having regular check-up and refused medication for years. Her clinical history and skin lesions led us to suspect of pyoderma gangrenosum (PG). The skin biopsy showed aseptic abscess formation with neutrophils infiltration in the dermis without bacteria. Thus, she was diagnosed with PG. 1 mg/kg/day of prednisolone was administered and ten sessions of granulocyte and monocyte adsorption apheresis (GMA) were started. Magnetic resonance cholangiography showed multifocal bile duct strictures due to PSC. Total colonoscopy revealed ulcerative pancolitis with spared normal mucosa in the rectum. After the treatments, her symptoms and the skin lesion improved dramatically. She was discharged on the 45th day with 25 mg/day of prednisolone. In conclusion, this is the first reported case of PG with PSC-associated colitis that showed dramatic response to the concomitant GMA therapy with corticosteroids. Together with previous reports, concomitant GMA therapy with corticosteroids may be an effective treatment for PG.

A case of gastric granular cell tumor.

We herein describe an extremely rare case of gastric granular cell tumor (GCT). The gastric submucosal tumor showed a central tiny depression on the surface with a molar tooth-like appearance on esophagogastroduodenoscopy. Our case highlights that gastric GCT should be considered as differential diagnosis of gastric submucosal tumors.

A case of a malignant serous neoplasm of the pancreas with synchronous vascular invasion and metachronous metastases.

Serous neoplasms (SNs) of the pancreas are usually considered benign tumors. However, they rarely manifest malignant behaviors. Here we present a case of malignant SN and review the literature of malignant SN. A 71-year-old woman presented to our hospital with a palpable abdominal mass. Imaging studies revealed a 7 cm mass with a cluster of microcysts having a honeycomb appearance in the head of the pancreas, which invaded the superior mesenteric vein (SMV). After being clinically diagnosed with SN, pancreaticoduodenectomy was performed with resection of limited SMV. Microscopically, the tumor was diagnosed as an SN concomitant with the tumor thrombus in the SMV. Four years after the surgery, two liver tumors and two peritoneal nodules were detected and three of them were surgically resected. All of those lesions had a honeycomb appearance in their cut surfaces and they were microscopically indistinguishable from the originally resected SN. A review of the literature identified 22 cases of malignant metastatic SNs published to date. Even though extremely rare, metachronous metastasis could occur in SNs of the pancreas. Local invasion indicated an increased likelihood of future metastasis. Thus, periodic surveillance should be considered for SNs after resection, especially when they have a local invasion.