The LIN28B-IMP1 post-transcriptional regulon has opposing effects on oncogenic signaling in the intestine.

RNA-binding proteins (RBPs) are expressed broadly during both development and malignant transformation, yet their mechanistic roles in epithelial homeostasis or as drivers of tumor initiation and progression are incompletely understood. Here we describe a novel interplay between RBPs LIN28B and IMP1 in intestinal epithelial cells. Ribosome profiling and RNA sequencing identified IMP1 as a principle node for gene expression regulation downstream from LIN28B In vitro and in vivo data demonstrate that epithelial IMP1 loss increases expression of WNT target genes and enhances LIN28B-mediated intestinal tumorigenesis, which was reversed when we overexpressed IMP1 independently in vivo. Furthermore, IMP1 loss in wild-type or LIN28B-overexpressing mice enhances the regenerative response to irradiation. Together, our data provide new evidence for the opposing effects of the LIN28B-IMP1 axis on post-transcriptional regulation of canonical WNT signaling, with implications in intestinal homeostasis, regeneration and tumorigenesis.

Neutrophil Extracellular Traps Promote Metastases of Colorectal Cancers through Activation of ERK Signaling by Releasing Neutrophil Elastase.

Neutrophil extracellular traps (NETs) play important roles in host immunity, as there is increasing evidence of their contribution to the progression of several types of cancers even though their role in colorectal cancers (CRCs) remains unclear. To investigate the clinical relevance of NETs in CRCs, we examined the expression of citrullinated histone H3 using immunohistochemistry and preoperative serum myeloperoxidase-DNA complexes in CRC patients using an enzyme-linked immunosorbent assay. High expression of intratumoral or systemic NETs was found to correlate with poor relapse-free survival (RFS), for which it is an independent prognostic factor. In vitro investigations of CRC cells (HCT116, HT29) revealed that NETs did not affect their proliferation but did promote the migration of CRC cells mediated by neutrophil elastase (NE) released during NETosis to increase extracellular signal-regulated kinase (ERK) activity. In vivo experiments using nude mice (KSN/slc) revealed that NE inhibition suppressed liver metastases in CRC cells, although it did not affect the growth of subcutaneously implanted tumors. Taken together, these results suggest that NET formation correlates with poor prognoses of patients with CRC and that the inhibition of NE could be a potential therapy for CRC metastases.

Posttranscriptional regulation of colonic epithelial repair by RNA binding protein IMP1/IGF2BP1.

RNA binding proteins, including IMP1/IGF2BP1, are essential regulators of intestinal development and cancer. Imp1 hypomorphic mice exhibit gastrointestinal growth defects, yet the specific role for IMP1 in colon epithelial repair is unclear. Our prior work revealed that intestinal epithelial cell-specific Imp1 deletion (Imp1ΔIEC ) was associated with better regeneration in mice after irradiation. Here, we report increased IMP1 expression in patients with Crohn's disease and ulcerative colitis. We demonstrate that Imp1ΔIEC mice exhibit enhanced recovery following dextran sodium sulfate (DSS)-mediated colonic injury. Imp1ΔIEC mice exhibit Paneth cell granule changes, increased autophagy flux, and upregulation of Atg5. In silico and biochemical analyses revealed direct binding of IMP1 to MAP1LC3B, ATG3, and ATG5 transcripts. Genetic deletion of essential autophagy gene Atg7 in Imp1ΔIEC mice revealed increased sensitivity of double-mutant mice to colonic injury compared to control or Atg7 single mutant mice, suggesting a compensatory relationship between Imp1 and the autophagy pathway. The present study defines a novel interplay between IMP1 and autophagy, where IMP1 may be transiently induced during damage to modulate colonic epithelial cell responses to damage.

[A Case of Spontaneous Spinal Epidural Hematoma during Chemotherapy with Paclitaxel and Ramucirumab for Advanced Gastric Cancer].

Spontaneous spinal epidural hematomas(SSEH)are rare. The causes of SSEH include hematologic disorders, anticoagulation and antiplatelet therapy, vascular malformations, neoplasms, trauma, or medical interventions, such as epidural catheterization or spinal surgery. However, the cause is usually unclear in most cases. We report a case of SSEH during chemotherapy with paclitaxel and ramucirumab for advanced gastric cancer. A 68-year-old woman was referred to our hospital with a diagnosis of advanced gastric cancer. After 4 courses of neoadjuvant chemotherapy containing S-1 plus oxaliplatin, distal gastrectomy with D2 lymphadenectomy was performed. Postoperative chemotherapy with paclitaxel and ramucirumab was initiated, with a diagnosis of ypStage Ⅲc(T4aN3bM0). She was later transported by ambulance to our hospital with symptoms of sudden onset posterior neck pain and weakness of the extremities. Magnetic resonance imaging(MRI)of her cervical spine showed an epidural hematoma from C2 to C5. The symptoms improved gradually after admission, and the epidural hematoma decreased in size on MRI. Hemorrhagic events such as SSEH should be considered during treatment with angiogenesis inhibitors.

IMP1 3' UTR shortening enhances metastatic burden in colorectal cancer.

The RNA-binding protein insulin-like growth factor 2 mRNA binding protein 1 (IMP1) is overexpressed in colorectal cancer (CRC); however, evidence for a direct role for IMP1 in CRC metastasis is lacking. IMP1 is regulated by let-7 microRNA, which binds in the 3' untranslated region (UTR) of the transcript. The availability of binding sites is in part controlled by alternative polyadenylation, which determines 3' UTR length. Expression of the short 3' UTR transcript (lacking all microRNA sites) results in higher protein levels and is correlated with increased proliferation. We used in vitro and in vivo model systems to test the hypothesis that the short 3' UTR isoform of IMP1 promotes CRC metastasis. Herein we demonstrate that 3' UTR shortening increases IMP1 protein expression and that this in turn enhances the metastatic burden to the liver, whereas expression of the long isoform (full length 3' UTR) does not. Increased tumor burden results from elevated tumor surface area driven by cell proliferation and cell survival mechanisms. These processes are independent of classical apoptosis pathways. Moreover, we demonstrate the shifts toward the short isoform are associated with metastasis in patient populations where IMP1-long expression predominates. Overall, our work demonstrates that different IMP1 expression levels result in different functional outcomes in CRC metastasis and that targeting IMP1 may reduce tumor progression in some patients.

Prostaglandin E2/EP Signaling in the Tumor Microenvironment of Colorectal Cancer.

The number of colorectal cancer (CRC) patients is increasing worldwide. Accumulating evidence has shown that the tumor microenvironment (TME), including macrophages, neutrophils, and fibroblasts, plays an important role in the development and progression of CRC. Although targeting the TME could be a promising therapeutic approach, the mechanisms by which inflammatory cells promote CRC tumorigenesis are not well understood. When inflammation occurs in tissues, prostaglandin E2 (PGE2) is generated from arachidonic acid by the enzyme cyclooxygenase-2 (COX-2). PGE2 regulates multiple functions in various immune cells by binding to the downstream receptors EP1, EP2, EP3, and EP4, and plays an important role in the development of CRC. The current therapies targeting PGE2 using non-steroidal anti-inflammatory drugs (NSAIDs) or COX-2 inhibitors have failed due to the global prostanoid suppression resulting in the severe adverse effects despite the fact they could prevent tumorigenesis. Therefore, therapies targeting the specific downstream molecules of PGE2 signaling could be a promising approach. This review highlights the role of each EP receptor in the TME of CRC tumorigenesis and their therapeutic potential.

The Role of Tumor-Associated Neutrophils in Colorectal Cancer.

Colorectal cancer (CRC) is one of the most common causes of cancer deaths worldwide and the number of CRC patients is increasing progressively. Despite the improvement of the surgical techniques and chemotherapy, we have not completely overcome this disease yet due to the metastases. Therefore, understanding the mechanisms through which metastasis occurs is important for overcoming CRC. Normal host cells in the tumor microenvironment, such as macrophages and fibroblasts, have been reported to promote the growth of CRCs. Although neutrophils were originally considered to have defensive functions against tumor cells, it has been revealed that some populations of neutrophils, called as tumor-associated neutrophils (TANs), have tumor-supportive functions. The plasticity between tumor-suppressive and -supportive neutrophils are regulated by transforming growth factor (TGF)-ß and Interferon-ß signaling. Some studies have demonstrated that TANs promote the spread of cancer cells to distant organs. TANs contribute to the tumor invasion and angiogenesis through the production of matrix metalloproteinase-9 (MMP9), vascular endothelial growth factor (VEGF), and hepatocyte growth factor (HGF) in the primary and metastatic sites. Neutrophils also promotes tumor cell dissemination by capturing circulating tumor cells using neutrophil extracellular traps and promote their migration to distant sites. The neutrophil-to-lymphocyte ratio is a well-defined predictive marker for CRC patients. In this review, we highlight the molecular signaling between TANs and CRC cells and the possibility of TANs as a potential target for cancer therapy.

Let-7 Represses Carcinogenesis and a Stem Cell Phenotype in the Intestine via Regulation of Hmga2.

Let-7 miRNAs comprise one of the largest and most highly expressed family of miRNAs among vertebrates, and is critical for promoting differentiation, regulating metabolism, inhibiting cellular proliferation, and repressing carcinogenesis in a variety of tissues. The large size of the Let-7 family of miRNAs has complicated the development of mutant animal models. Here we describe the comprehensive repression of all Let-7 miRNAs in the intestinal epithelium via low-level tissue-specific expression of the Lin28b RNA-binding protein and a conditional knockout of the MirLet7c-2/Mirlet7b locus. This ablation of Let-7 triggers the development of intestinal adenocarcinomas concomitant with reduced survival. Analysis of both mouse and human intestinal cancer specimens reveals that stem cell markers were significantly associated with loss of Let-7 miRNA expression, and that a number of Let-7 targets were elevated, including Hmga1 and Hmga2. Functional studies in 3-D enteroids revealed that Hmga2 is necessary and sufficient to mediate many characteristics of Let-7 depletion, namely accelerating cell cycle progression and enhancing a stem cell phenotype. In addition, inactivation of a single Hmga2 allele in the mouse intestine epithelium significantly represses tumorigenesis driven by Lin28b. In aggregate, we conclude that Let-7 depletion drives a stem cell phenotype and the development of intestinal cancer, primarily via Hmga2.

[In vivo imaging of intracellular signaling molecules: Come/Stop signals of neutrophils during acute inflammation].

Many chemical mediators regulate neutrophil recruitment to inflammatory sites. Although the actions of each of these chemical mediators have been demonstrated with neutrophils in vitro, how they act cooperatively or counteract each other in vivo remains largely unknown. To understand the behaviors of neutrophils in vivo, the activities of intracellular signaling molecules must be visualized in living tissues. For this purpose, we can use genetically-encoded biosensors based on the principle of Förster resonance energy transfer (FRET). In this review, we first provide an overview of FRET biosensors and then describe how we can utilize these biosensors to visualize the activity changes of signaling molecules in neutrophils during extravasation. In relation to this topic, we will also describe the development of transgenic mice expressing the FRET biosensors and in vivo two-photon excitation microscopy.

IGF2BP1/IMP1 Deletion Enhances a Facultative Stem Cell State via Regulation of MAP1LC3B.

BACKGROUND & AIMS: The intestinal epithelium interfaces with a diverse milieu of luminal contents while maintaining robust digestive and barrier functions. Facultative intestinal stem cells are cells that survive tissue injury and divide to re-establish the epithelium. Prior studies have shown autophagic state as functional marker of facultative intestinal stem cells, but regulatory mechanisms are not known. The current study evaluated a post-transcriptional regulation of autophagy as an important factor for facultative stem cell state and tissue regeneration. METHODS: We evaluated stem cell composition, autophagic vesicle content, organoid formation, and in vivo regeneration in mice with intestinal epithelial deletion of the RNA binding protein IGF2 messenger RNA binding protein 1 (IMP1). The contribution of autophagy to resulting in vitro and in vivo phenotypes was evaluated via genetic inactivation of Atg7. Molecular analyses of IMP1 modulation of autophagy at the protein and transcript localization levels were performed using IMP1 mutant studies and single-molecule fluorescent in situ hybridization. RESULTS: Epithelial Imp1 deletion reduced leucine rich repeat containing G protein coupled receptor 5 cell frequency but enhanced both organoid formation efficiency and in vivo regeneration after irradiation. We confirmed prior studies showing increased autophagy with IMP1 deletion. Deletion of Atg7 reversed the enhanced regeneration observed with Imp1 deletion. IMP1 deletion or mutation of IMP1 phosphorylation sites enhanced expression of essential autophagy protein microtubule-associated protein 1 light chain 3ß. Furthermore, immunofluorescence imaging coupled with single-molecule fluorescent in situ hybridization showed IMP1 colocalization with MAP1LC3B transcripts at homeostasis. Stress induction led to decreased colocalization. CONCLUSIONS: Depletion of IMP1 enhances autophagy, which promotes intestinal regeneration via expansion of facultative intestinal stem cells.

Downregulation of osteoprotegerin in colorectal cancer cells promotes liver metastasis via activating tumor-associated macrophage.

Osteoprotegerin (OPG) is a secreted cytokine that functions as a decoy receptor for receptor activator of nuclear factor kappa-B (RANK) ligand (RANKL). Anti-RANKL treatment for bone metastasis has been widely accepted for solid tumors. However, the mechanism of OPG-RANKL-RANK signaling in systemic colorectal cancer (CRC) metastasis remains unclear. In this study, we investigated the relevance and function of OPG expression in CRC liver metastasis. First, we performed in silico analysis using The Cancer Genome Atlas public database and found that lower OPG expression in CRC was associated with poor overall survival. Immunohistochemistry analyses using resected specimen from patients with CRC in our institute confirmed the result. Patient-matched primary CRC and liver metastases showed a significant downregulation of OPG expression in metastatic lesions. In CRC cell lines, OPG expression did not suppress cell proliferation and migration. However, OPG expression inhibited macrophage migration by suppressing the RANKL-RANK pathway. Moreover, in vivo mouse liver metastasis models showed that OPG expression in CRC cells suppressed liver metastases. In addition, treatment with an anti-RANKL neutralizing antibody also suppressed liver metastases. These results showed that downregulation of OPG expression in CRC cells promotes liver metastasis by activating tumor-associated macrophage, which can become a candidate for targeted therapy with anti-RANKL neutralizing antibody for CRC liver metastasis.

Live imaging of protein kinase activities in transgenic mice expressing FRET biosensors.

Genetically-encoded biosensors based on the principle of Förster resonance energy transfer (FRET) have been widely used in biology to visualize the spatiotemporal dynamics of signaling molecules. Despite the increasing multitude of these biosensors, their application has been mostly limited to cultured cells with transient biosensor expression, due to particular difficulties in the development of transgenic mice that express FRET biosensors. In this study, we report the efficient generation of transgenic mouse lines expressing heritable and functional biosensors for ERK and PKA. These transgenic mice were created by the cytoplasmic co-injection of Tol2 transposase mRNA and a circular plasmid harbouring Tol2 recombination sites. High expression of the biosensors in a wide range of cell types allowed us to screen newborn mice simply by inspection. Observation of these transgenic mice by two-photon excitation microscopy yielded real-time activity maps of ERK and PKA in various tissues, with greatly improved signal-to-background ratios. Our transgenic mice may be bred into diverse genetic backgrounds; moreover, the protocol we have developed paves the way for the generation of transgenic mice that express other FRET biosensors, with important applications in the characterization of physiological and pathological signal transduction events in addition to drug development and screening.

Strangulated small bowel obstruction caused by isolated obturator nerve and pelvic vessels after pelvic lymphadenectomy in gynecologic surgery: two case reports.

BACKGROUND: Although small bowel obstruction (SBO) is a major complication occurring after abdominal surgery, few reports have described strangulated SBO after pelvic lymphadenectomy (PL). This report describes two cases of strangulated SBO caused by a skeletonized obturator nerve and pelvic vessels after laparoscopic PL during gynecologic surgery. CASE PRESENTATION: Case 1: A 57-year-old woman with endometrial cancer underwent a laparoscopic semi-radical total hysterectomy with PL. Nine months after the operation, she visited our emergency room complaining about subacute pain spreading in the right groin, right buttock, and dorsal part of the right thigh. She had no abdominal pain. Although her symptoms were not typical, computed tomography (CT) revealed strangulated SBO in the right pelvis. Laparoscopic surgery revealed that the small bowel was ischemic. Then we converted to open surgery. We transected the right obturator nerve and umbilical artery, which constructed an internal hernia orifice in the right pelvis, followed by resection of the ischemic small bowel. Fortunately, during 6-month follow-up, she showed only slight difficulty in walking as a postoperative complication. Case 2: A 62-year-old woman with cervical cancer underwent laparoscopic radical hysterectomy with PL. Six months after the operation, she visited our hospital emergently because of sudden onset of abdominal pain and vomiting. CT showed strangulated SBO. Urgent laparoscopic surgery exhibited the incarcerated small bowel at the right pelvis. Consequently, we converted to open surgery. The terminal ileum was detained into the space constructed by the right umbilical artery. We cut the umbilical artery and performed ileocecal resection. After the surgery, she was discharged with no complication or sequela. CONCLUSION: When examining a patient after PL who complains of severe pain or symptoms, one should consider the possibility of PL-related SBO, even if the pain is apparently atypical for SBO.

A case of acute appendicitis incarcerated in obturator hernia.

An 85 year-old woman was transferred with a chief complaint of right thigh pain persisting for 5 days. Abdominal contrast-enhanced computed tomography clearly depicted a swollen appendix incarcerated in the right obturator cavity. She underwent an emergent laparoscopic appendectomy and the simultaneous repair of the obturator hernia. At laparoscopy, appendix was found to be incarcerated in the right obturator canal. The incarcerated appendix was successfully flushed out from the sac by spurting saline into the obturator hernia sac through the catheter inserted into the hernia sac. After a laparoscopic appendectomy, the hernia orifice was repaired using the uterine flap. The patient was discharged from the hospital without any sequelae. This report demonstrates a very rare case of obturator hernia incarcerated with appendix. Although patients with obturator hernia incarcerated with small intestine present with the symptoms related to bowel obstruction, patients with incarceration of appendix do not. Moreover, they would show no typical abdominal symptoms associated with acute appendicitis. Therefore, it is important to perform a radiological evaluation promptly to make a definitive diagnosis when a patient with persisting pain of the right thigh or right ileac fossa with a possibility of obturator hernia with incarceration of the appendix is encountered.

Intra-abdominal desmoid tumor mimicking locoregional recurrence after colectomy in a patient with sporadic colon cancer: report of a case.

Desmoid tumors are rare, benign fibromatous lesions that result from the abnormal proliferation of myofibroblasts. A 61-year-old man underwent laparoscopy-assisted right hemicolectomy for ascending colon cancer. The final TNM stage was stage IIIB (T3N1M0). Follow-up computed tomography (CT), done 12 months after primary surgery, showed a nodular, enhancing soft-tissue density mass, 12 mm in size, in the mesentery, near the anastomosis. Another CT scan, done 4 months later, revealed that the tumor had enlarged to 27 mm in size. We suspected locoregional recurrence of colon cancer and resected the tumor, together with the distal ileum and colon, including the previous anastomotic site. The tumor was histologically diagnosed as a desmoid tumor. The patient remains well 24 months after his last operation. Differentiating between the desmoid tumor and locoregional recurrent tumor was difficult, and surgical resection was the optimal treatment.

Idiopathic Omental Bleeding Treated by Laparoscopic Partial Omentectomy: A Case Report and Review of the Literature.

Omental bleeding is potentially life-threatening. There are many causes of omental bleeding including trauma, neoplasia, arterial aneurysm rupture, omental torsion, vasculitis, or segmental arterial mediolysis (SAM). Without remarkable pathological features, the diagnosis of idiopathic omental bleeding is made. Omental bleeding is relatively a rare disease, and there is no established treatment strategy.  A 53-year-old woman was brought to the ED for sudden onset abdominal pain. CT revealed hematoma in the omentum and was diagnosed as idiopathic omental bleeding accordingly. The patient underwent laparoscopic partial omentectomy and was discharged nine days after surgery. The pathological findings of the resected omentum were not remarkable, and the final diagnosis was made as idiopathic omental bleeding. In some case reports of omental bleeding, interventional radiology (IVR) was chosen for hemostasis, but IVR cannot resect tissue of omentum so it is difficult to make a pathological diagnosis. The surgical approach of idiopathic omental bleeding is uncommon. However, the use of the laparoscopic approach hasn't been reported in the literature. Laparoscopic partial omentectomy can provide effective hemostasis. We report laparoscopic partial omentectomy surgical procedure and review of the literature.

Combination of lymphocyte count and albumin concentration as a new prognostic biomarker for rectal cancer.

Although numerous studies have highlighted the prognostic values of various inflammation-related markers, clinical significance remains to be elucidated. The prognostic values of inflammation-related biomarkers for rectal cancer were investigated in this study. A total of 448 patients with stage II/III rectal cancer undergoing curative resection were enrolled from the discovery cohort (n = 240) and validation cohort (n = 208). We comprehensively compared the prognostic values of 11 inflammation-related markers-derived from neutrophil, lymphocyte, platelet, monocyte, albumin, and C-reactive protein for overall survival (OS) and recurrence-free survival (RFS). Among 11 inflammation-related markers, only "lymphocyte × albumin (LA)" was significantly associated with both OS and RFS in the discovery cohort (P = 0.007 and 0.015, respectively). Multivariate analysis indicated that low LA was significantly associated with poor OS (hazard ratio [HR] 2.19, 95% confidence interval [CI] 1.09-4.58, P = 0.025), and poor RFS (HR 1.61, 95% CI 1.01-2.80, P = 0.048). Furthermore, using the discovery cohort, we confirmed that low LA was significantly associated with poor OS (HR 2.89, 95% CI 1.42-6.00, P = 0.002), and poor RFS (HR 1.79, 95% CI 1.04-2.95, P = 0.034). LA can be a novel prognostic biomarker for stage II/III rectal cancer.

LIN28B induces a differentiation program through CDX2 in colon cancer.

Most colorectal cancers (CRCs) are moderately differentiated or well differentiated, a status that is preserved even in metastatic tumors. However, the molecular mechanisms underlying CRC differentiation remain to be elucidated. Herein, we unravel a potentially novel posttranscriptional regulatory mechanism via a LIN28B/CDX2 signaling axis that plays a critical role in mediating CRC differentiation. Owing to a large number of mRNA targets, the mRNA-binding protein LIN28B has diverse functions in development, metabolism, tissue regeneration, and tumorigenesis. Our RNA-binding protein IP (RIP) assay revealed that LIN28B directly binds CDX2 mRNA, which is a pivotal homeobox transcription factor in normal intestinal epithelial cell identity and differentiation. Furthermore, LIN28B overexpression resulted in enhanced CDX2 expression to promote differentiation in subcutaneous xenograft tumors generated from CRC cells and metastatic tumor colonization through mesenchymal-epithelial transition in CRC liver metastasis mouse models. A ChIP sequence for CDX2 identified α-methylacyl-CoA racemase (AMACR) as a potentially novel transcriptional target of CDX2 in the context of LIN28B overexpression. We also found that AMACR enhanced intestinal alkaline phosphatase activity, which is known as a key component of intestinal differentiation, through the upregulation of butyric acid. Overall, we demonstrated that LIN28B promotes CRC differentiation through the CDX2/AMACR axis.

Effect of herbal medicine daikenchuto on gastrointestinal symptoms following laparoscopic colectomy in patients with colon cancer: A prospective randomized study.

We conducted a prospective randomized study to investigate the effect of daikenchuto (DKT) on abdominal symptoms following laparoscopic colectomy in patients with left-sided colon cancer. Patients who suffered from abdominal pain or distention on postoperative day 1 were randomized to either the DKT group or non-DKT group. The primary endpoints were the evaluation of abdominal pain, abdominal distention, and quality of life. The metabolome and gut microbiome analyses were conducted as secondary endpoints. A total of 17 patients were enrolled: 8 patients in the DKT group and 9 patients in the non-DKT group. There were no significant differences in the primary endpoints and postoperative adverse events between the two groups. The metabolome and gut microbiome analyses showed that the levels of plasma lipid mediators associated with the arachidonic acid cascade were lower in the DKT group than in the non-DKT group, and that the relative abundance of genera Serratia and Bilophila were lower in the DKT group than in the non-DKT group. DKT administration did not improve the abdominal symptoms following laparoscopic colectomy. The effects of DKT on metabolites and gut microbiome have to be further investigated.