Background: Endoscopic self-expandable metallic stent (SEMS) placement is a widely accepted treatment for malignant left-sided colorectal obstruction (LSO) because of its lower invasiveness and quicker symptomatic relief compared to surgery. However, SEMS placement for ileocecal valve obstruction (ICVO) has not been established due to its technical difficulties. Methods: This single-center retrospective study compared the clinical outcomes of patients who underwent SEMS placement for ICVO (ICVO group, n = 13) and LSO (LSO group, n = 146). Particularly in cases with severe small-intestine dilation, we applied a “Two-Step Strategy”, which involved long intestinal tube insertion followed by SEMS placement to ensure safety and overcome technical challenges. Results: Patients in the ICVO group were significantly more likely to undergo SEMS placement with the Two-Step Strategy compared to those in the LSO group (76.9% vs. 6.9%, p < 0.001). Both groups achieved similarly high technical and clinical success rates (100% vs. 98.6%, p = 1.000; 92.3% vs. 88.4%, p = 1.000), and the incidence of adverse events also showed no significant difference between the groups (7.7% vs. 13.0%; p = 1.000). Furthermore, the median time to recurrent colorectal obstruction and survival time after SEMS placement did not differ between patients with palliative stenting for ICVO and LSO (not reached vs. 430 days, p = 0.586; 119 days vs. 200 days, p = 0.303). Conclusions: SEMS placement for malignant ICVO is as safe and effective as it is for malignant LSO, and the Two-Step Strategy might be useful in ICVO cases.

Background Gastric cancer is often accompanied by a loss of MUC6, but its pathogenic role in gastric carcinogenesis remains unclear. Method Muc6 knockout (Muc6-/-) mice and Muc6-dsRED mice were newly generated. Tff1Cre, Golph3-/-, R26-Golgi-mCherry, Hes1flox/flox, Cosmcflox/flox, A4gnt-/- mice were also used. Histology, DNAs and RNAs, proteins, and sugar chains were analyzed by whole exon DNA sequence, RNA sequence, immunohistochemistry, lectin-binding assays, and LC-MS analysis. Gastric organoids and cell lines were used for in vitro assays and xenograft experiments. Result Deletion of Muc6 in mice spontaneously causes pan-gastritis and invasive gastric cancers. Muc6-deficient tumor growth was dependent on MAPK activation, mediated by Golgi stress-induced upregulation of GOLPH3. Glycomic profiling revealed aberrant expression of mannose-rich N-linked glycans in gastric tumors, detected with Banana lectin in association with lack of MUC6 expression. We identified a precursor of clusterin as a binding partner of mannose glycans. MAPK activation, Golgi stress responses, aberrant mannose expression are found in a separate Cosmc- and A4gnt-deficient mouse models which lack normal O-glycosylation. Banana lectin-drug conjugates proved an effective treatment for mannose-rich murine and human gastric cancer. Conclusion We propose that Golgi stress responses and aberrant glycans are important drivers of, and promising new therapeutic targets for gastric cancer.

Trastuzumab deruxtecan (T-DXd) has demonstrated remarkable efficacy as a third- or later-line chemotherapy for human epidermal growth factor receptor 2 (HER2)-positive advanced gastric and gastroesophageal junction adenocarcinomas. However, it may cause pneumonitis, and its efficacy in rare histologies such as gastric adenocarcinoma with enteroblastic differentiation (GAED) remains unclear. A 74-year-old woman with unresectable HER2-positive GAED and lung metastasis received T-DXd as a fifth-line chemotherapy. Treatment was discontinued after 15 cycles owing to drug-induced pneumonitis; however, the patient achieved a sustained complete response for 14 months without subsequent chemotherapy or the exacerbation of pneumonitis. T-DXd was effective in HER2-positive GAED.

BACKGROUND & AIMS:Gastric chief cells, a mature cell type that secretes digestive enzymes, have been proposed to be the origin of metaplasia and cancer through dedifferentiation or transdifferentiation. However, studies supporting this claim have had technical limitations, including issues with the specificity of chief cell markers and the toxicity of drugs used. We therefore sought to identify genes expressed specifically in chief cells and establish a model to trace these cells.METHODS:We performed transcriptome analysis of Mist1-CreERT-traced cells, with or without chief cell depletion. Gpr30-rtTA mice were generated and crossed to TetO-Cre mice, and lineage tracing was performed after crosses to R26-TdTomato mice. Additional lineage tracing experiments were performed using Mist1-CreERT, Kitl-CreERT, Tff1-Cre, and Tff2-Cre mice crossed to reporter mice. Mice were given high-dose tamoxifen or DMP-777 or were infected with Helicobacter pylori to induce gastric metaplasia. We studied mice that expressed mutant forms of Ras in gastric cells, using TetO-KrasG12D, LSL-KrasG12D, and LSL-HrasG12V mice. We analyzed stomach tissues from GPR30-knockout mice. Mice were given dichloroacetate to inhibit pyruvate dehydrogenase kinase (PDK)-dependent cell competition.RESULTS:We identified GPR30, the G-protein-coupled form of the estrogen receptor, as a cell-specific marker of chief cells in gastric epithelium of mice. Gpr30-rtTA mice crossed to TetO-Cre;R26-TdTomato mice had specific expression of GPR30 in chief cells, with no expression noted in isthmus stem cells or lineage tracing of glands. Expression of mutant Kras in GPR30+ chief cells did not lead to the development of metaplasia or dysplasia but, instead, led to a reduction in labeled numbers of chief cells and a compensatory expansion of neck lineage, which was derived from upper Kitl+ clones. Administration of high-dose tamoxifen, DMP-777, or H pylori decreased the number of labeled chief cells. Chief cells were eliminated from epithelia via GPR30- and PDK-dependent cell competition after metaplastic stimuli, whereas loss of GRP30 or inhibition of PDK activity preserved chief cell numbers and attenuated neck lineage cell expansion.CONCLUSIONS:In tracing studies of mice, we found that most chief cells are lost during metaplasia and therefore are unlikely to contribute to gastric carcinogenesis. Expansion of cells that coexpress neck and chief lineage markers, known as spasmolytic polypeptide-expressing metaplasia, does not occur via dedifferentiation from chief cells but, rather, through a compensatory response from neck progenitors to replace the eliminated chief cells.

The tumor microenvironment favors the growth and expansion of cancer cells. Many cell types are involved in the tumor microenvironment such as inflammatory cells, fibroblasts, nerves, and vascular endothelial cells. These stromal cells contribute to tumor growth by releasing various molecules to either directly activate the growth signaling in cancer cells or remodel surrounding areas. This review introduces recent advances in findings on the interactions within the tumor microenvironment such as in cancer-associated fibroblasts (CAFs), immune cells, and endothelial cells, in particular those established in mouse gastric cancer models. In mice, myofibroblasts in the gastric stroma secrete R-spondin and support normal gastric stem cells. Most CAFs promote tumor growth in a paracrine manner, but CAF population appears to be heterogeneous in terms of their function and origin, and include both tumor-promoting and tumor-restraining populations. Among immune cell populations, tumor-associated macrophages, including M1 and M2 macrophages, and myeloid-derived suppressor cells (MDSCs), are reported to directly or indirectly promote gastric tumorigenesis by secreting soluble factors or modulating immune responses. Endothelial cells or blood vessels not only fuel tumors with nutrients, but also interact with cancer stem cells and immune cells by secreting chemokines or cytokines, and act as a cancer niche. Understanding these interactions within the tumor microenvironment would contribute to unraveling new therapeutic targets.

The mechanism of H. pylori-induced atrophy and metaplasia has not been fully understood. Here, we demonstrate the novel role of Apoptosis signal-regulating kinase 1 (ASK1) and downstream MAPKs as a regulator of host immune responses and epithelial maintenance against H. pylori infection. ASK1 gene deficiency resulted in enhanced inflammation with numerous inflammatory cells including Gr-1+CD11b+ myeloid-derived suppressor cells (MDSCs) recruited into the infected stomach. Increase of IL-1β release from apoptotic macrophages and enhancement of TH1-polarized immune responses caused STAT1 and NF-κB activation in epithelial cells in ASK1 knockout mice. Dysregulated immune and epithelial activation in ASK1 knockout mice led to dramatic expansion of gastric progenitor cells and massive metaplasia development. Bone marrow transplantation experiments revealed that ASK1 in inflammatory cells is critical for inducing immune disorder and metaplastic changes in epithelium, while ASK1 in epithelial cells regulates cell proliferation in stem/progenitor zone without changes in inflammation and differentiation. These results suggest that H. pylori-induced immune cells may regulate epithelial homeostasis and cell fate as an inflammatory niche via ASK1 signaling.

extract (WPE) against NSAIDs-induced gastric damages along with molecular mechanisms for future clinical implications.RGM-1 gastric mucosal cells were administered with NSAIDs and compared the expressions of inflammatory mediators after indomethacin alone or combination of indomethacin and WPE.The expressions of inflammatory mediators, including COX-1 & COX-2, prostaglandin E2, 15-hydroxyprostaglandin dehydrogenase (15-PGDH), and anti-oxidant capacity, were analyzed by Western blot analysis, RT-PCR, and ELISA, respectively.HO-1, Nrf-2, keap1 of phase 2 enzymes were investigated.In vivo animal models were followed with in vitro investigations.NSAID increased the expression of COX-2 and decreased COX-1 and 15-PGDH, but WPE significantly attenuated NSAID-induced COX-2 expression.Interestingly, WPE induced expression of 15-PGDH.By using deletion constructs of the 15-PGDH promoter, we have found that c-Jun is the most essential determinant for WPE-induced up-regulation of 15-PGDH expression.We confirmed that knockdown of c-Jun abolished the ability of WPE to up-regulate 15-PGDH expression.In addition, WPE significantly increased HO-1 expression.WPE increased nuclear translocation of Nrf2 by Keap-1 degradation and silencing Nrf2 markedly reduced the WPE-induced HO-1 expression.We have found that WPE-induced HO-1 up-regulation was attenuated in cells harbouring the mutant Keap1 in which the cysteine 151 residue was replaced by serine.These in vitro findings were exactly validated in indomethacin-induced gastric rat models.Daily walnut intake can be promising nutritional supplement providing potent anti-inflammatory, anti-oxidative, and mucosa protective effects against NSAID-induced GI damages.

To understand the regulation of Helicobacter pylori ( H. pylori )-associated gastric carcinogenesis, we examined the effect of B-cell translocation gene 2 (BTG2) expression on the biological activity of Tipα, an oncoprotein secreted from H. pylori. BTG2, the human ortholog of mouse TIS21 (BTG2 /TIS21 ), has been reported to be a primary response gene that is transiently expressed in response to various stimulations. Here, we report that BTG2 is constitutively expressed in the mucous epithelium and parietal cells of the gastric gland in the stomach. Expression was increased in the mucous epithelium following H. pylori infection in contrast to its loss in human gastric adenocarcinoma. Indeed, adenoviral transduction of BTG2 /TIS21 significantly inhibited Tipα activity in MKN-1 and MGT-40, human and mouse gastric cancer cells, respectively, thereby downregulating tumor necrosis factor-α (TNFα) expression and Erk1/2 phosphorylation by reducing expression of nucleolin, a Tipα receptor. Chromatin immunoprecipitation proved that BTG2 /TIS21 inhibited Sp1 expression and its binding to the promoter of the nucleolin gene. In addition, BTG2 /TIS21 expression significantly reduced membrane-localized nucleolin expression in cancer cells, and the loss of BTG2 /TIS21 expression induced cytoplasmic nucleolin availability in gastric cancer tissues, as evidenced by immunoblotting and immunohistochemistry. Higher expression of BTG2 and lower expression of nucleolin were accompanied with better overall survival of poorly differentiated gastric cancer patients. This is the first report showing that BTG2 /TIS21 inhibits nucleolin expression via Sp1 binding, which might be associated with the inhibition of H. pylori -induced carcinogenesis. We suggest that BTG2 /TIS21 is a potential inhibitor of nucleolin in the cytoplasm, leading to inhibition of carcinogenesis after H. pylori infection.

To understand the regulation of Helicobacter pylori (H. pylori)-associated gastric carcinogenesis, we examined the effect of B-cell translocation gene 2 (BTG2) expression on the biological activity of Tip alpha, an oncoprotein secreted from H. pylori. BTG2, the human ortholog of mouse TIS21 (BTG2(/TIS21)), has been reported to be a primary response gene that is transiently expressed in response to various stimulations. Here, we report that BTG2 is constitutively expressed in the mucous epithelium and parietal cells of the gastric gland in the stomach. Expression was increased in the mucous epithelium following H. pylori infection in contrast to its loss in human gastric adenocarcinoma. Indeed, adenoviral transduction of BTG2(/TIS21) significantly inhibited Tip alpha activity in MKN-1 and MGT-40, human and mouse gastric cancer cells, respectively, thereby downregulating tumor necrosis factor-alpha (TNF alpha) expression and Erk1/2 phosphorylation by reducing expression of nucleolin, a Tip alpha receptor. Chromatin immunoprecipitation proved that BTG2(/TIS21) inhibited Sp1 expression and its binding to the promoter of the nucleolin gene. In addition, BTG2(/TIS21) expression significantly reduced membrane-localized nucleolin expression in cancer cells, and the loss of BTG2(/TIS21) expression induced cytoplasmic nucleolin availability in gastric cancer tissues, as evidenced by immunoblotting and immunohistochemistry. Higher expression of BTG2 and lower expression of nucleolin were accompanied with better overall survival of poorly differentiated gastric cancer patients. This is the first report showing that BTG2(/TIS21) inhibits nucleolin expression via Sp1 binding, which might be associated with the inhibition of H. pylori-induced carcinogenesis. We suggest that BTG2(/TIS21) is a potential inhibitor of nucleolin in the cytoplasm, leading to inhibition of carcinogenesis after H. pylori infection.

BACKGROUND & AIMS:The intestinal epithelium is maintained by long-lived intestinal stem cells (ISCs) that reside near the crypt base. Above the ISC zone, there are short-lived progenitors that normally give rise to lineage-specific differentiated cell types but can dedifferentiate into ISCs in certain circumstances. However, the role of epithelial dedifferentiation in cancer development has not been fully elucidated.METHODS:We performed studies with Bhlha15-CreERT, Lgr5-DTR-GFP, Apcflox/flox, LSL-Notch (IC), and R26-reporter strains of mice. Some mice were given diphtheria toxin to ablate Lgr5-positive cells, were irradiated, or were given 5-fluorouracil, hydroxyurea, doxorubicin, or dextran sodium sulfate to induce intestinal or colonic tissue injury. In intestinal tissues, we analyzed the fate of progeny that expressed Bhlha15. We used microarrays and reverse-transcription PCR to analyze gene expression patterns in healthy and injured intestinal tissues and in tumors. We analyzed gene expression patterns in human colorectal tumors using The Cancer Genome Atlas data set.RESULTS:Bhlha15 identified Paneth cells and short-lived secretory precursors (including pre-Paneth label-retaining cells) located just above the ISC zone in the intestinal epithelium. Bhlha15+ cells had no plasticity after loss of Lgr5-positive cells or irradiation. However, Bhlha15+ secretory precursors started to supply the enterocyte lineage after doxorubicin-induced epithelial injury in a Notch-dependent manner. Sustained activation of Notch converts Bhlha15+ secretory precursors to long-lived enterocyte progenitors. Administration of doxorubicin and expression of an activated form of Notch resulted in a gene expression pattern associated with enterocyte progenitors, whereas only sustained activation of Notch altered gene expression patterns in Bhlha15+ precursors toward those of ISCs. Bhlha15+ enterocyte progenitors with sustained activation of Notch formed intestinal tumors with serrated features in mice with disruption of Apc. In the colon, Bhlha15 marked secretory precursors that became stem-like, cancer-initiating cells after dextran sodium sulfate-induced injury, via activation of Src and YAP signaling. In analyses of human colorectal tumors, we associated activation of Notch with chromosome instability-type tumors with serrated features in the left colon.CONCLUSIONS:In mice, we found that short-lived precursors can undergo permanent reprogramming by activation of Notch and YAP signaling. These cells could mediate tumor formation in addition to traditional ISCs.

(-)-Epigallocatechin gallate (EGCG), a green tea catechin, acts as a synergist with various anticancer drugs, including retinoids. Am80 is a synthetic retinoid with a different structure from all-trans-retinoic acid: Am80 is now clinically utilized as a new drug for relapsed and intractable acute promyelocytic leukemia patients. Our experiments showed that the combination of EGCG and Am80 synergistically induced both apoptosis in human lung cancer cell line PC-9 and up-regulated expressions of growth arrest and DNA damage-inducible gene 153 (GADD153), death receptor 5, and p21waf1 genes in the cells. To understand the mechanisms of synergistic anticancer activity of the combination, we gave special attention to the lysine acetylation of proteins. Proteomic analysis using nanoLC-ESI-MS/MS revealed that PC-9 cells treated with the combination contained 331 acetylated proteins, while nontreated cells contained 553 acetylated proteins, and 59 acetylated proteins were found in both groups. Among them, the combination increased acetylated-p53 and acetylated-α-tubulin through reduction of histone deacetylase (HDAC) activity in cytosol fraction, although the levels of acetylation in histones H3 or H4 did not change, and the combination reduced protein levels of HDAC4, -5 and -6 by 20% to 80%. Moreover, we found that a specific inhibitor of HDAC4 and -5 strongly induced p21waf1 gene expression, and that of HDAC6 induced both GADD153 and p21waf1 gene expression, which resulted in apoptosis. All results demonstrate that EGCG in combination with Am80 changes levels of acetylation in nonhistone proteins via down-regulation of HDAC4, -5 and -6 and stimulates apoptotic induction.

Abstract A synthetic new retinoid Am80 (tamibarotene) is used for treatment of acute promyelocytic leukemia (APL) patients with resistance of all-trans-retinoic acid (ATRA). To potentiate efficacy of Am80, we challenged combination treatment of Am80 and EGCG on human lung cancer cell line PC-9. It is now well accepted that EGCG acts as synergist with numerous anticancer compounds, and that the average reduction of tumor volume for in vivo genograft mouse models implanted using various human cancer cell lines was 70.3% with combinations of 13 anticancer compounds and EGCG. We previously reported that combinations of NSAIDs (sulindac and celecoxib) or other retinoids (ATRA, 13-cis-RA and 9-cis-RA) and EGCG synergistically induced apoptosis of the cells along with strong expression of growth arrest and DNA-damage inducible gene 153 (GADD153) and death receptor (DR5) gene. Our objective was to investigate the mechanism of the synergistic induction for GADD153-DR5 apoptosis pathway. The proteomic analysis of lysine-acetylated proteins was conducted with a shotgun analysis using nanoLC-ESI-MS/MS in PC-9 cells. We found that the numbers of acetylated proteins were different: 551 acetylated proteins were found in non-treated cells, 331 proteins in cells treated with combination, and 59 proteins were common in both cases. Acetylation was mainly found in non-histone proteins, chaperons, transcription factors, and enzymes. The combination increased acetylated p53 (Lys382) about 3-fold compared with non-treated cells. In addition, combination significantly decreased the protein amounts of histone deacetylase (HDAC) 4 and HDAC 5 to 50% and 20%, respectively, but not HDAC6 among Class II HDACs. Class I HDACs (HDAC1, 2, and 3) were not decreased. All the results suggest that combination of Am80 and EGCG induces GADD153-DR5 apoptotic pathway, and reduces the amounts of HDAC4 and HDAC5 resulting in changing protein acetylation. Citation Format: Masami Suganuma, Yukiko Oya, Sonthaya Umsumarng, Keisuke Iida, Anchalee Rawangkhan, Ryo Sakai, Hiroyuki Kagechika, Koichi Shudo, Hirota Fujiki. Innovative cancer treatment of human lung cancer cells PC-9 with a synthetic retinoid Am80 and EGCG via inhibition of HDAC4 and HDAC5. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4723.