Michihiro Yoshida, Itaru Naitoh, Kazuki Hayashi, Naruomi Jinno, Yasuki Hori, Makoto Natsume, Akihisa Kato, Kenta Kachi, Go Asano, Naoki Atsuta, Hidenori Sahashi, and Hiromi Kataoka. Gut and Liver 2021;15:476-85. https://doi.org/10.5009/gnl20238

INTRODUCTION: Immune checkpoint inhibitors (ICIs) are being increasingly used to treat advanced malignancies. ICI-induced pancreatic injury (ICI-PI), which is an immune-related adverse event that may be a risk factor of ICI-associated pancreatitis, is not well documented in the literature. METHODS: Consecutive patients who received ICIs for advanced malignancies from August 2015 through October 2022 were analyzed for the incidence of ICI-PI based on the Common Terminology Criteria for Adverse Events and ICI-associated pancreatitis. The imaging, clinical, and pathological findings of ICI-associated pancreatitis were also assessed. RESULTS: This study enrolled 843 patients. In multivariable analyses, dual or simultaneous immunotherapy and ≥10 cycles of ICI administration were significant predictive factors for all grades of pancreatic injury, including grade ≥3. Notably, patients who received simultaneous immunotherapy exhibited a higher incidence of grade ≥3 pancreatic injuries compared with those receiving asynchronous immunotherapy in univariable analysis (P = 0.032). One-fifth of the patients (16/70) with grade ≥3 pancreatic injuries had imaging evidence of pancreatitis similar to mild acute pancreatitis. ICI-associated pancreatitis was observed in 5.7% (48/843) of patients, including 1.8% (15/843) with moderate-to-severe pancreatitis (grade ≥2). Symptomatic cases (0.36%, 3/843) were treated with steroids with favorable outcomes. Immunohistochemistry for CD4 and CD8 revealed greater infiltration of CD8⁺ than CD4⁺ lymphocytes. DISCUSSION: Simultaneous immunotherapy and dual immunotherapy are risk factors of ICI-PI. Although most patients diagnosed with ICI-PI and ICI-associated pancreatitis were asymptomatic and had a low mortality likelihood, long-term outcomes, including endocrine and exocrine function, should be carefully monitored.

Sampling of bile juice during endoscopic retrograde cholangiopancreatography (ERCP) has potential benefit of being amenable to the identification of novel biomarkers in liquid biopsy. This study reports the results of a global investigation of exosomal microRNAs (miRNAs) in bile to identify potential biomarkers for biliary tract cancers (BTCs). Eighty‐eight bile samples collected during ERCP (45 BTC and 43 noncancer control samples) were enrolled in this study. Eleven BTC samples and nine control samples were assigned as the discovery set. Exosomes in bile and serum samples were collected using a glass membrane column with size‐controlled macroporous glass (MPG), and exosomal miRNA expression profiles were evaluated using comprehensive miRNA microarray analysis (3D‐Gene). For validation, exosomal miRNA in the bile samples of 34 BTCs and 34 controls were comprehensively evaluated using 3D‐Gene. In the discovery set, eight exosomal miRNAs in bile were identified as significant aberrant expression markers, while no miRNA with aberrant expression in serum was identified. In a comparison of the discovery and validation sets, miR‐451a and miR‐3619‐3p were identified as reproducible upregulated markers, and the combination of the two bile miRNAs showed an excellent area under the curve (0.819) value for diagnosing BTCs. In addition, high miR‐3619‐3p expression in bile reflects poorer prognosis of BTCs (hazard ratio = 2.89). The MPG‐extracted exosomal miRNAs in bile aspirated during ERCP provide a convenient new approach for diagnosing biliary diseases. Bile‐derived miRNA analysis with miR‐451a and miR‐3619‐3p represents a potentially valuable diagnostic strategy for identifying BTCs as well as a predictive indicator of BTC prognosis.

Peritoneal dissemination and malignant ascites in pancreatic ductal adenocarcinoma (PDAC) patients represent a major clinical issue. Lysophosphatidic acid (LPA) is a lipid mediator that modulates various cancer progression. Based on the increasing evidence showing that LPA is abundant in malignant ascites, we focused on Autotaxin (ATX), which is a secreted enzyme that is important for the production of LPA. This study aimed to elucidate the importance of the ATX‐LPA axis in malignant ascites in PDAC, and to determine whether ATX works as a molecular target for treating peritoneal dissemination. In a PDAC peritoneal dissemination mouse model, the amount of ATX was significantly higher in ascites than in serum. An in vitro study using two PDAC cell lines, AsPC‐1 and PANC‐1, showed that ATX‐LPA signaling promoted cancer cell migration via the activation of the downstream signaling, and this increased cell migration was suppressed by an ATX inhibitor, PF‐8380. An in vivo study showed that PF‐8380 suppressed peritoneal dissemination and decreased malignant ascites, and these results were validated by the biological analysis as well as the in vitro study. Moreover, there was a positive correlation between the amount of ATX in ascites and the degree of disseminated cancer progression. These findings demonstrated that ATX in ascites works as a promotor of peritoneal dissemination, and the targeting of ATX must represent a useful and novel therapy for peritoneal dissemination of PDAC.

Membrane-anchored heparin-binding epidermal growth factor-like growth factor (proHB-EGF) yields soluble HB-EGF, which is an epidermal growth factor receptor (EGFR) ligand, and a carboxy-terminal fragment of HB-EGF (HB-EGF-CTF) after ectodomain shedding. We previously reported that HB-EGF-CTF and unshed proHB-EGF which has the cytoplasmic domain of proHB-EGF (HB-EGF-C), translocate from the plasma membrane to the nucleus and regulate cell cycle after shedding stimuli. However, the significance of nuclear exported HB-EGF-C in human gastric cancer is unclear. We investigated the relationship between intracellular localization of HB-EGF-C and clinical outcome in 96 gastric cancer patients treated with gastrectomy. Moreover, we established stable gastric cancer cell lines overexpressing wild-type HB-EGF (wt-HB-EGF) and mutated HB-EGF (HB-EGF-mC), which prevented HB-EGF-C nuclear translocation after shedding. Cell motility between these 2 gastric cancer cell lines was investigated using a transwell invasion assay and a wound healing assay. Of the 96 gastric cancer cases, HB-EGF-C immunoreactivity was detected in both the nucleus and cytoplasm in 19 cases (19.8 %) and in the cytoplasm only in 25 cases (26.0 %). The nuclear immunoreactivity of HB-EGF-C was significantly increased in stage pT3/4 tumors compared with pT1/2 tumors (T1/2 vs. T3/4: 11.1 % vs. 36.4 %, P < 0.01). The growth of wt-HB-EGF- and HB-EGF-mC-expressing cells significantly increased compared with control cells, but the growth of HB-EGF-mC-expressing cells was significantly decreased compared with wt-HB-EGF-expressing cells. Gastric cancer cell invasion obviously increased in wt-HB-EGF-expressing cells, but invasion in HB-EGF-mC-expressing cells showed a slight increase compared with control cells. Moreover, wt-HB-EGF overexpression increased the effectiveness of wound healing, but had no significant effect in HB-EGF-mC-expressing cells. Both the function of HB-EGF as an EGFR ligand and a novel signal for HB-EGF-C nuclear translocation induce gastric cancer growth, whereas HB-EGF-C nuclear translocation independently plays a critical role in gastric cancer invasion. The present study demonstrated that HB-EGF-C nuclear translocation might be crucial in gastric cancer invasion. HB-EGF-C nuclear translocation may offer a prognostic marker and a new molecular target for gastric cancer therapy.

The Na⁺/H⁺ exchanger regulatory factor (NHERF) family of proteins is scaffolds that orchestrate interaction of receptors and cellular proteins. Previous studies have shown that NHERF1 functions as a tumor suppressor. The goal of this study is to determine whether the loss of NHERF2 alters colorectal cancer (CRC) progress. We found that NHERF2 expression is elevated in advanced-stage CRC. Knockdown of NHERF2 decreased cancer cell proliferation in vitro and in a mouse xenograft tumor model. In addition, deletion of NHERF2 in Apc ^Min/+ mice resulted in decreased tumor growth in Apc ^Min/+ mice and increased lifespan. Blocking NHERF2 interaction with a small peptide designed to bind the second PDZ domain of NHERF2 attenuated cancer cell proliferation. Although NHERF2 is known to facilitate the effects of lysophosphatidic acid receptor 2 (LPA₂), transcriptome analysis of xenograft tumors revealed that NHERF2-dependent genes largely differ from LPA₂-regulated genes. Activation of β-catenin and ERK1/2 was mitigated in Apc ^Min/+; Nherf2^{− /−} adenomas. Moreover, Stat3 phosphorylation and CD24 expression levels were suppressed in Apc ^Min/+; Nherf2^{− /−} adenomas. Consistently, NHERF2 knockdown attenuated Stat3 activation and CD24 expression in colon cancer cells. Interestingly, CD24 was important in the maintenance of Stat3 phosphorylation, whereas NHERF2-dependent increase in CD24 expression was blocked by inhibition of Stat3, suggesting that NHERF2 regulates Stat3 phosphorylation through a positive feedback mechanism between Stat3 and CD24. In summary, this study identifies NHERF2 as a novel oncogenic protein and a potential target for cancer treatment. NHERF2 potentiates the oncogenic effects in part by regulation of Stat3 and CD24.