A novel twin-grasper assisted mucosal inverted closure technique for closing large artificial gastric mucosal defects.

BACKGROUND: Large artificial gastric mucosal defects are always left unclosed for natural healing due to technique difficulties in closure. This study aims to evaluate the feasibility and safety of a new Twin-grasper Assisted Mucosal Inverted Closure (TAMIC) technique in closing large artificial gastric mucosal defects. METHODS: Endoscopic submucosal dissection (ESD) was performed in fifteen pigs to create large gastric mucosal defects. The mucosal defects were then either left unclosed or closed with metallic clips using TAMIC technique. Successful closure rate and the wound outcomes were assessed. RESULTS: Two mucosal defects with size of about 4.0 cm were left unclosed and healed two months after surgery. Thirteen large gastric mucosal defects were created by ESD with a medium size of 5.9 cm and were successfully closed with the TAMIC technique (100%), even in a mucosal defect with a width up to 8.5 cm. The mean closure time was 59.0 min. Wounds in eight stomachs remained completely closed 1 week after surgery (61.5%), while closure in the other five stomachs had partial wound dehiscence (38.5%). Four weeks later, all the closed defects healed well and 61.5% of the wounds still remained completely closed during healing. There was no delayed perforation or bleeding after surgery. In addition, there was less granulation in the submucosal layer of the closed wound sites than those under natural healing. CONCLUSIONS: The present study suggests that TAMIC is feasible and safe in closing large artificial gastric mucosal defects and could improve mucosal recovery compared to natural healing process.

Twin-grasper assisted mucosal inverted closure achieves complete healing of large perforations after gastric endoscopic full-thickness resection.

OBJECTIVES: This study aimed to demonstrate the feasibility and safety of a novel twin-grasper assisted mucosal inverted closure (TAMIC) technique for large perforations after gastric endoscopic full-thickness resection (EFTR) in a porcine model. METHODS: Iatrogenic large perforations of the stomach were created and closed by an experienced endoscopist using the TAMIC technique in 12 pigs. Repeat gastroscopy was performed in 4 weeks after surgery to examine the wound sites and then the animals were killed. The primary outcomes were the successful TAMIC closure rate and the complete healing rate. Secondary end points included procedure time of TAMIC, complete inverted healing rate, delayed bleeding rate, and postsurgery perforation. Histologies of the wounds were analyzed by hematoxylin-eosin, Masson trichrome, and immunohistochemistry staining. RESULTS: The median size of the defects was 3.5 (range 2.5-4.5) cm. TAMIC was successfully performed in all the 12 pigs. Complete healing was achieved in 11 pigs 4 weeks after operation as one pig died postsurgery due to severe pneumonia. The median procedure time for TAMIC was 39 (range 23-81) min. The complete inverted healing rate was 45.5% (5/11). No delayed bleeding or postsurgery perforation was observed. Histologic analyses showed that both the epithelium and muscularis mucosae layers were appropriately connected under inverted healing. CONCLUSIONS: Twin-grasper assisted mucosal inverted closure is feasible and safe for closure of large perforations after gastric EFTR and could be a propagable and promising technique for clinical practice.

Pleiotropic Roles of Atrial Natriuretic Peptide in Anti-Inflammation and Anti-Cancer Activity.

The atrial natriuretic peptide (ANP), a cardiovascular hormone, plays a pivotal role in the homeostatic control of blood pressure, electrolytes, and water balance and is approved to treat congestive heart failure. In addition, there is a growing realization that ANPs might be related to immune response and tumor growth. The anti-inflammatory and immune-modulatory effects of ANPs in the tissue microenvironment are mediated through autocrine or paracrine mechanisms, which further suppress tumorigenesis. In cancers, ANPs show anti-proliferative effects through several molecular pathways. Furthermore, ANPs attenuate the side effects of cancer therapy. Therefore, ANPs act on several hallmarks of cancer, such as inflammation, angiogenesis, sustained tumor growth, and metastasis. In this review, we summarized the contributions of ANPs in diverse aspects of the immune system and the molecular mechanisms underlying the anti-cancer effects of ANPs.

Erratum: Overexpression of TC2N is associated with poor prognosis in gastric cancer: Erratum.

[This corrects the article DOI: 10.7150/jca.50653.].

Laparoscopy-endoscopy Cooperative Surgery for the Treatment of Gastric Gastrointestinal Stromal Tumors.

In view of the shortcomings of endoscopic or laparoscopic surgeries alone in the treatment of gastric gastrointestinal stromal tumors (G-GISTs), this approach makes an innovative improvement in the treatment of G-GISTs that are less than 5 cm in size. Laparoscopy-endoscopy cooperative surgery (LECS) is used to combine endoscopic and laparoscopic surgeries, fully realizing their respective advantages and avoiding their drawbacks. The main steps are as follows. First, gastroscopy and laparoscopy are combined to confirm the location and boundary of the tumor. Tumor resection is carried out laparoscopically, guided by a gastroscope. The specimen is removed orally and the gastric wound closed laparoscopically. Then, gastroscopy and laparoscopy are combined to determine whether there is wound bleeding, if the suture is satisfactory, and if the gastric cavity is deformed. LECS has natural advantages in the treatment of G-GISTs that are less than 5 cm in size. The accurate estimation of tumor location and boundary greatly improves the complete resection rate of tumors. The risk of tumor rupture is substantially reduced, and the long-term prognosis of patients is significantly improved. The process allows for accurate resection of the tumor, maximum preservation of normal gastric tissue and organ function, and avoids postoperative gastric deformation. The patient's postoperative rehabilitation is greatly accelerated, and oral feeding can resume on the day of the operation. The specimen is taken out through the mouth to avoid the need for an extended abdominal incision. This greatly reduces the patient's postoperative pain and scarring. The method greatly shortens the postoperative hospital stay (i.e., discharge is possible on the day after the operation), increasing the turnover of hospital beds.

MAPK4 promotes triple negative breast cancer growth and reduces tumor sensitivity to PI3K blockade.

About 15-20% of breast cancer (BCa) is triple-negative BCa (TNBC), a devastating disease with limited therapeutic options. Aberrations in the PI3K/PTEN signaling pathway are common in TNBC. However, the therapeutic impact of PI3K inhibitors in TNBC has been limited and the mechanism(s) underlying this lack of efficacy remain elusive. Here, we demonstrate that a large subset of TNBC expresses significant levels of MAPK4, and this expression is critical for driving AKT activation independent of PI3K and promoting TNBC cell and xenograft growth. The ability of MAPK4 to bypass PI3K for AKT activation potentially provides a direct mechanism regulating tumor sensitivity to PI3K inhibition. Accordingly, repressing MAPK4 greatly sensitizes TNBC cells and xenografts to PI3K blockade. Altogether, we conclude that high MAPK4 expression defines a large subset or subtype of TNBC responsive to MAPK4 blockage. Targeting MAPK4 in this subset/subtype of TNBC both represses growth and sensitizes tumors to PI3K blockade.

MAPK6-AKT signaling promotes tumor growth and resistance to mTOR kinase blockade.

Mitogen-activated protein kinase 6 (MAPK6) is an atypical MAPK. Its function in regulating cancer growth remains elusive. Here, we reported that MAPK6 directly activated AKT and induced oncogenic outcomes. MAPK6 interacted with AKT through its C34 region and the C-terminal tail and phosphorylated AKT at S473 independent of mTORC2, the major S473 kinase. mTOR kinase inhibitors have not made notable progress in the clinic. Our identified MAPK6-AKT axis may provide a major resistance pathway. Besides repressing growth, inhibiting MAPK6 sensitized cancer cells to mTOR kinase inhibitors. MAPK6 overexpression is associated with decreased overall survival and the survival of patients with lung adenocarcinoma, mesothelioma, uveal melanoma, and breast cancer. MAPK6 expression also correlated with AKT phosphorylation at S473 in human cancer tissues. We conclude that MAPK6 can promote cancer by activating AKT independent of mTORC2 and targeting MAPK6, either alone or in combination with mTOR blockade, may be effective in cancers.

MAPK4 promotes prostate cancer by concerted activation of androgen receptor and AKT.

Prostate cancer (PCa) is the second leading cause of cancer death in American men. Androgen receptor (AR) signaling is essential for PCa cell growth/survival and remains a key therapeutic target for lethal castration-resistant PCa (CRPC). GATA2 is a pioneer transcription factor crucial for inducing AR expression/activation. We recently reported that MAPK4, an atypical MAPK, promotes tumor progression via noncanonical activation of AKT. Here, we demonstrated that MAPK4 activated AR by enhancing GATA2 transcriptional expression and stabilizing GATA2 protein through repression of GATA2 ubiquitination/degradation. MAPK4 expression correlated with AR activation in human CRPC. Concerted activation of both GATA2/AR and AKT by MAPK4 promoted PCa cell proliferation, anchorage-independent growth, xenograft growth, and castration resistance. Conversely, knockdown of MAPK4 decreased activation of both AR and AKT and inhibited PCa cell and xenograft growth, including castration-resistant growth. Both GATA2/AR and AKT activation were necessary for MAPK4 tumor-promoting activity. Interestingly, combined overexpression of GATA2 plus a constitutively activated AKT was sufficient to drive PCa growth and castration resistance, shedding light on an alternative, MAPK4-independent tumor-promoting pathway in human PCa. We concluded that MAPK4 promotes PCa growth and castration resistance by cooperating parallel pathways of activating GATA2/AR and AKT and that MAPK4 is a novel therapeutic target in PCa, especially CRPC.

Overexpression of TC2N is associated with poor prognosis in gastric cancer.

Background: Tac2-N (TC2N) is a tandem C2 domain-containing protein, acting as a novel oncogene or suppressor in different kinds of cancers. However, the status of TC2N expression and its significance in gastric cancer (GC) is still unclear. The present study is aimed to elucidate the clinicopathological significance and prognostic value of TC2N level in GC. Methods: We used sequencing data from the Cancer Genome Atlas (TCGA) database to analyze TC2N expression in GC by UALCAN database and Gene Expression Profiling Interactive Analysis tools (GEPIA). TC2N expression level in 12 pairs of fresh GC tissues and adjacent nontumorous tissues was detected by quantitative real-time reverse-transcription polymerase chain reaction (RT-PCR) and Western blot (WB) assays. Immunohistochemical (IHC) staining was used to detect TC2N protein expression in Paraffin-embedded tissues in our center. In vitro proliferation, migration and invasion assays were used to evaluate the effect of TC2N on functional capability of gastric cancer cells. LinkedOmics was used to identify gene expressions associated with TC2N. Results: The mRNA and protein expression of TC2N in gastric cancer were both significantly higher than normal gastric mucosa. It was also elevated in gastric cancer cells compared with normal gastric epithelium cell. In vitro assays suggested that TC2N facilitated proliferation, migration and invasion of gastric cancer cells. Bioinformatic analysis showed a widespread impact of TC2N on the transcriptome and a strong interaction with tumor associated genes. We also found that TC2N was an independent prognostic factor for long-term survival in GC patients and its high expression was evidently associated with poor overall survival and recurrence-free survival. Conclusions: Our results show that high level of TC2N correlates with poor prognosis in patients with gastric cancer and promotes the development of gastric cancer. Thus, TC2N expression can serve as a prognostic biomarker for patients with gastric cancer.

Association of Preoperative Serum Carcinoembryonic Antigen and Gastric Cancer Recurrence: A Large Cohort Study.

Background and Aim: Measuring postoperative carcinoembryonic antigen (CEA) is recommended by guidelines to help detecting recurrence of gastric cancer patients. However, the prognostic significance of elevated preoperative CEA is unclear. This study aims to investigate whether patients with elevated preoperative CEA have a higher risk of recurrence than patients with normal preoperative CEA. Methods: We conducted a retrospective cohort study at a gastric cancer center in South China. Consecutive patients with stage I to III gastric adenocarcinoma who underwent curative resection at the center from January 2001 to February 2016 were identified. Patients were grouped into two cohorts: normal preoperative CEA (≤ 5 ng/ml), and elevated preoperative CEA (> 5 ng/ml). 3-year recurrence-free survival (RFS) and hazard function curves over time were estimated. Results: A total of 1,596 patients (1,063 {66.6%} male; median {Interquartile range, IQR} age, 59 {50-66} years) were identified. Patients with elevated preoperative CEA had 15.5% lower 3-year RFS (n=222 {70.4%}) than the cohorts with normal preoperative CEA (n=1,374 {85.9%}). The hazard function of recurrence for the two cohorts peaked at the similar time (around 10 months after surgery). Multivariate Cox analyses confirmed that elevated preoperative CEA was independently associated with shorter RFS (Hazard Ratio {HR}, 1.69; 95% confidence interval {CI}, 1.26-2.27; P = 0.001). Conclusions: Patients with elevated preoperative CEA are at increased risk for recurrence, especially within the first 24 months after surgery.

p53-Induced LINC00893 Regulates RBFOX2 Stability to Suppress Gastric Cancer Progression.

Long noncoding RNAs (lncRNAs) have been reported to regulate diverse tumorigenic processes. However, little is known about long intergenic non-protein coding RNA 00893 (LINC00893) and its role in gastric cancer (GC). Herein we investigated its biological functions and molecular mechanism in GC. LINC00893 was decreased in GC tissues but significantly elevated in AGS cells after treatment with Nutlin-3. In GC patients, it was found that low expression of LINC00893 was correlated with tumor growth, metastasis and poor survival. Functionally, overexpression of LINC00893 suppressed the proliferation, migration and invasion of GC cells. Mechanistically, LINC00893 regulated the expression of epithelial-mesenchymal transition (EMT)-related proteins by binding to RNA binding fox-1 homolog 2 (RBFOX2) and promoting its ubiquitin-mediated degradation, thus suppressing the EMT and related functions of GC. In addition, the transcription factor p53 can regulate the expression of LINC00893 in an indirect way. Taken together, these results suggested that LINC00893 regulated by p53 repressed GC proliferation, migration and invasion by functioning as a binding site for RBFOX2 to regulate its stability and the expression of EMT-related proteins. LINC00893 acts as a tumor-inhibiting lncRNA that is induced by p53 in GC and regulates EMT by binding to RBFOX2, thus providing a novel experimental basis for the clinical treatment of GC.

Inflammation-Associated Senescence Promotes Helicobacter pylori-Induced Atrophic Gastritis.

BACKGROUND & AIMS: The association between cellular senescence and Helicobacter pylori-induced atrophic gastritis is not clear. Here, we explore the role of cellular senescence in H pylori-induced atrophic gastritis and the underlying mechanism. METHODS: C57BL/6J mice were infected with H pylori for biological and mechanistic studies in vivo. Gastric precancerous lesions from patients and mouse models were collected and analyzed using senescence-associated beta-galactosidase, Sudan Black B, and immunohistochemical staining to analyze senescent cells, signaling pathways, and H pylori infection. Chromatin immunoprecipitation, luciferase reporter assays, and other techniques were used to explore the underlying mechanism in vitro. RESULTS: Gastric mucosa atrophy was highly associated with cellular senescence. H pylori promoted gastric epithelial cell senescence in vitro and in vivo in a manner that depended on C-X-C motif chemokine receptor 2 (CXCR2) signaling. Interestingly, H pylori infection not only up-regulated the expression of CXCR2 ligands, C-X-C motif chemokine ligands 1 and 8, but also transcriptionally up-regulated the expression of CXCR2 via the nuclear factor-κB subunit 1 directly. In addition, CXCR2 formed a positive feedback loop with p53 to continually enhance senescence. Pharmaceutical inhibition of CXCR2 in an H pylori-infected mouse model attenuated mucosal senescence and atrophy, and delayed further precancerous lesion progression. CONCLUSIONS: Our study showed a new mechanism of H pylori-induced atrophic gastritis through CXCR2-mediated cellular senescence. Inhibition of CXCR2 signaling is suggested as a potential preventive therapy for targeting H pylori-induced atrophic gastritis. GEO data set accession numbers: GSE47797 and GSE3556.

CD155T/TIGIT Signaling Regulates CD8+ T-cell Metabolism and Promotes Tumor Progression in Human Gastric Cancer.

The T-cell surface molecule TIGIT is an immune checkpoint molecule that inhibits T-cell responses, but its roles in cancer are little understood. In this study, we evaluated the role TIGIT checkpoint plays in the development and progression of gastric cancer. We show that the percentage of CD8 T cells that are TIGIT+ was increased in gastric cancer patients compared with healthy individuals. These cells showed functional exhaustion with impaired activation, proliferation, cytokine production, and metabolism, all of which were rescued by glucose. In addition, gastric cancer tissue and cell lines expressed CD155, which bound TIGIT receptors and inactivated CD8 T cells. In a T cell-gastric cancer cell coculture system, gastric cancer cells deprived CD8 T cells of glucose and impaired CD8 T-cell effector functions; these effects were neutralized by the additional glucose or by TIGIT blockade. In gastric cancer tumor cells, CD155 silencing increased T-cell metabolism and IFNγ production, whereas CD155 overexpression inhibited T-cell metabolism and IFNγ production; this inhibition was neutralized by TIGIT blockade. Targeting CD155/TIGIT enhanced CD8 T-cell reaction and improved survival in tumor-bearing mice. Combined targeting of TIGIT and PD-1 further enhanced CD8 T-cell activation and improved survival in tumor-bearing mice. Our results suggest that gastric cancer cells inhibit CD8 T-cell metabolism through CD155/TIGIT signaling, which inhibits CD8 T-cell effector functions, resulting in hyporesponsive antitumor immunity. These findings support the candidacy of CD155/TIGIT as a potential therapeutic target in gastric cancer. Cancer Res; 77(22); 6375-88. ©2017 AACR.