AMP-18 Targets p21 to Maintain Epithelial Homeostasis

Hyperoside Alleviates Helicobacter pylori-Induced Gastric Epithelial Cell Injury by Regulating Nrf2/HO-1 Signaling

Infection with Helicobacter pylori is the major causative factor of chronic gastritis, peptic ulcer, gastric cancer, and other diseases. Gastric mucosal epithelial injury characterized by abnormal apoptosis, oxidative stress, and inflammation is a crucial mechanism of H. pylori infection. Hyperoside (HYP) is a flavonol glycoside derived from many herbal plants, which exhibits potent anti-apoptotic, antioxidant, and anti-inflammatory properties. Our research explored whether it exerts protective effects on H. pylori-infected human gastric epithelial cells. GES-1 cells were first treated for 24 h with HYP (0, 10, 20, 40, 80, 100, or 120 μM) to determine the cytotoxicity of HYP. Subsequently, GES-1 cells were pre-treated for 4 h with HYP (80 μM), followed by exposure to H. pylori for 24 h. CCK-8 assay, flow cytometry assay, ELISA, RT-qPCR, DCFH-DA staining, the commercial assay kits, immunofluorescence staining, and western blotting were used to assess cell viability, cell apoptosis, pro-inflammatory cytokine levels, oxidative stress marker levels, and Nrf2/HO-1 signaling-related molecule levels. The Nrf2 inhibitor ML385 was employed to verify the beneficial role of Nrf2 activation in HYP-mediated GES-1 cell injury induced by H. pylori. The results showed that HYP pre-treatment reversed H. pylori-induced cell apoptosis, inflammation, and oxidative stress in GES-1 cells. Furthermore, HYP downregulated Nrf2, HO-1, and NQO1 protein levels in H. pylori-infected GES-1 cells. ML385 overturned the protective effects of HYP against H. pylori-induced GES-1 cell apoptosis, inflammation, and oxidative stress. In conclusion, HYP protects gastric epithelial cells against H. pylori-induced cell injury by activating the Nrf2/HO-1 pathway.

Keratin 14-high subpopulation mediates lung cancer metastasis potentially through Gkn1 upregulation

Metastasis is the leading cause of lung cancer-related death. Elucidating the metastasis process can provide new avenues to inhibit this malignant behavior of cancer cells. Here we found that human lung cancers with high Keratin 14 (K14) expression were associated with nodal metastasis and poor survival. Using the Kras^G12D/Trp53^L/L lung cancer mouse model, we confirmed that K14-high cancer cells harbored increased metastatic potential. Mechanistic investigation revealed that Gastrokine 1 (Gkn1) expression positively correlated with K14 level, cancer metastasis, and poor patient survival. Importantly, ectopic expression of Gkn1 enhanced the metastatic capability of K14-low cells in vitro and in vivo, whereas knockdown of Gkn1 did the opposite, indicating the importance of Gkn1 in mediating the metastasis of K14-high cells. Further study demonstrated that Gkn1 expression conferred K14-high cells resistance to anoikis, which is critical for cancer metastasis. Collectively, our findings demonstrate that K14-high cells contribute to lung cancer metastasis potentially through inhibition of anoikis via upregulation of Gkn1.

Regulation of GKN1 expression in gastric carcinogenesis: A problem to resolve (Review)

Gastrokine 1 (GKN1) is a protein expressed on the surface mucosa cells of the gastric antrum and fundus, which contributes to maintaining gastric homeostasis, inhibits inflammation and is a tumor suppressor. The expression of GKN1 decreases in mucosa that are either inflamed or infected by Helicobacter pylori, and is absent in gastric cancer. The measurement of circulating GKN1 concentration, the protein itself, or the mRNA in gastric tissue may be of use for the early diagnosis of cancer. The mechanisms that modulate the deregulation or silencing of GKN1 expression have not been completely described. The modification of histones, methylation of the GKN1 promoter, or proteasomal degradation of the protein have been detected in some patients; however, these mechanisms do not completely explain the absence of GKN1 or the reduction in GKN1 levels. Only NKX6.3 transcription factor has been shown to be a positive modulator of GKN1 transcription, although others also have an affinity with sequences in the promoter of this gene. While microRNAs (miRNAs) are able to directly or indirectly regulate the expression of genes at the post‑transcriptional level, the involvement of miRNAs in the regulation of GKN1 has not been reported. The present review analyzes the information reported on the determination of GKN1 expression and the regulation of its expression at the transcriptional, post‑transcriptional and post‑translational levels; it proposes an integrated model that incorporates the regulation of GKN1 expression via transcription factors and miRNAs in H. pylori infection.

Gastrokine 1 protein is a potential theragnostic target for gastric cancer

BACKGROUND

Gastrokine 1 (GKN1) plays important roles in maintaining mucosal homeostasis, and in regulating cell proliferation and differentiation. Here, we determined whether GKN1 is a potential theragnostic marker for gastric cancer.

METHODS

We identified GKN1 binding proteins using the protein microarray assay and investigated whether GKN1 is one of the exosomal cargo proteins by western blot, immunoprecipitation, and immunofluorescent assays. Cell proliferation and apoptosis were analyzed by MTT, BrdU incorporation, flow cytometry, and western blot assays. We further validated the functional relevance of exosomal GKN1 in MKN1-injected xenograft mice. The possibility of serum GKN1 as a diagnostic marker for gastric cancer was determined by ELISA assay.

RESULTS

In protein microarray assay, GKN1 binding to 27 exosomal proteins was clearly observed. GKN1 was expressed in exosomes derived from HFE-145 gastric epithelial cells by western blot and immunofluorescent assays, but not in exosomes from AGS and MKN1 gastric cancer cells. Exosomes carrying GKN1 inhibited cell proliferation and induced apoptosis in both AGS and MKN1 cells, and exosomes carrying GKN1-treated nude mice-bearing MKN1 xenograft tumors exhibited significantly reduced tumor volume and tumor weight. Silencing of clathrin markedly down-regulated the internalization of exosomal GKN1. Interestingly, serum GKN1 concentrations in patients with gastric cancer were significantly lower than those in healthy individuals and patients with colorectal and hepatocellular carcinomas.

CONCLUSIONS

The GKN1 is secreted and internalized in the gastric epithelium by exosome-driven transfer, which inhibits gastric tumorigenesis and supports the clinical application of GKN1 protein in gastric cancer diagnosis and treatment.

Spatiotemporally Controlled Ablation of Klf5 Results in Dysregulated Epithelial Homeostasis in Adult Mouse Corneas

Purpose

Corneal epithelial (CE) homeostasis requires coordination between proliferation and differentiation. Here we examine the role of cell proliferation regulator Krüppel-like factor 5 (Klf5) in adult mouse CE homeostasis.

Methods

Klf5 was ablated in a spatiotemporally restricted manner by inducing Cre expression in 8-week-old ternary transgenic Klf5LoxP/LoxP/Krt12rtTA/rtTA/Tet-O-Cre (Klf5Δ/ΔCE) mouse CE by administering doxycycline via chow. Normal chow-fed ternary transgenic siblings served as controls. The control and Klf5Δ/ΔCE corneal (1) histology, (2) cell proliferation, and (3) Klf5-target gene expression were examined using (1) periodic acid Schiff reagent-stained sections, (2) Ki67 expression, and (3) quantitative PCR and immunostaining, respectively. The effect of KLF4, KLF5, and OCT1 on gastrokine-1 (GKN1) promoter activity was determined by transient transfection in human skin keratinocyte NCTC-2544 cells.

Results

Klf5 expression was decreased to 23% of the controls in Klf5Δ/ΔCE corneas, which displayed increased fluorescein uptake, downregulation of tight junction proteins Tjp1 and Gkn1, desmosomal Dsg1a, and basement membrane Lama3 and Lamb1, suggesting defective permeability barrier. In transient transfection assays, KLF5 and OCT1 synergistically stimulated GKN1 promoter activity. Klf5Δ/ΔCE CE displayed significantly fewer cell layers and Ki67+ proliferative cells coupled with significantly decreased cyclin-D1, and elevated phospho(Ser-10) p27/Kip1 expression. Expression of Krt12, E-cadherin, and β-catenin remained unaltered in Klf5Δ/ΔCE corneas.

Conclusions

Klf5 contributes to adult mouse CE homeostasis by promoting (1) permeability barrier function through upregulation of Tjp1, Gkn1, Dsg1a, Lama3, and Lamb1, and (2) basal cell proliferation through upregulation of cyclin-D1 and suppression of phospho(Ser-10) p27/Kip1, without significantly affecting the expression of epithelial markers Krt12, E-cadherin, and β-catenin.

Specific MicroRNA Pattern in Colon Tissue of Young Children with Eosinophilic Colitis

Eosinophilic colitis (EC) is a common cause of haematochezia in infants and young children. The exact pathomechanism is not understood, and the diagnosis is challenging. The role of microRNAs as key class of regulators of mRNA expression and translation in patients with EC has not been explored. Therefore, the aim of the present study was to explore the miRNA profile in EC with respect to eosinophilic inflammation. Patients enrolled in the study (n = 10) had persistent rectal bleeding, and did not respond to elimination dietary treatment. High-throughput microRNA sequencing was carried out on colonic biopsy specimens of children with EC (EC: n = 4) and controls (C: n = 4) as a preliminary screening of the miRNA profile. Based on the next-generation sequencing (NGS) results and literature data, a potentially relevant panel of miRNAs were selected for further measurements by real-time reverse transcription (RT)-PCR (EC: n = 14, C: n = 10). Validation by RT-PCR resulted in significantly altered expression of miR-21, -31, -99b, -125a, -146a, -184, -221, -223, and -559 compared to controls (p ≤ 0.05). Elevation in miR-21, -99b, -146a, -221, and -223 showed statistically significant correlation to the extent of tissue eosinophilia. Based on our results, we conclude that the dysregulated miRNAs have a potential role in the regulation of apoptosis by targeting Protein kinase B/Mechanistic target of rapamycin (AKT/mTOR)-related pathways in inflammation by modulating Nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB)-related signalling and eosinophil cell recruitment and activation, mainly by regulating the expression of the chemoattractant eotaxin and the adhesion molecule CD44. Our results could serve as a basis for further extended research exploring the pathomechanism of EC.

A Novel Peptide for Simultaneously Enhanced Treatment of Head and Neck Cancer and Mitigation of Oral Mucositis

We have characterized a novel 21 amino acid-peptide derived from Antrum Mucosal Protein (AMP)-18 that mediates growth promotion of cultured normal epithelial cells and mitigates radiation-induced oral mucositis in animal models, while suppressing in vitro function of cancer cells. The objective of this study was to evaluate these dual potential therapeutic effects of AMP peptide in a clinically relevant animal model of head and neck cancer (HNC) by simultaneously assessing its effect on tumor growth and radiation-induced oral mucositis in an orthotopic model of HNC. Bioluminescent SCC-25 HNC cells were injected into the anterior tongue and tumors that formed were then subjected to focal radiation treatment. Tumor size was assessed using an in vivo imaging system, and the extent of oral mucositis was compared between animals treated with AMP peptide or vehicle (controls). Synergism between AMP peptide and radiation therapy was suggested by the finding that tumors in the AMP peptide/radiation therapy cohort demonstrated inhibited growth vs. radiation therapy-only treated tumors, while AMP peptide-treatment delayed the onset and reduced the severity of radiation therapy-induced oral mucositis. A differential effect on apoptosis appears to be one mechanism by which AMP-18 can stimulate growth and repair of injured mucosal epithelial cells while inhibiting proliferation of HNC cells. RNA microarray analysis identified pathways that are differentially targeted by AMP-18 in HNC vs. nontransformed cells. These observations confirm the notion that normal cells and tumor cells may respond differently to common biological stimuli, and that leveraging this finding in the case of AMP-18 may provide a clinically relevant opportunity.

Antrum Mucosal Protein-18 Peptide Targets Tight Junctions to Protect and Heal Barrier Structure and Function in Models of Inflammatory Bowel Disease

BACKGROUND

A peptide derived from Antrum Mucosal Protein (AMP)-18 (gastrokine-1) reduces the extent of mucosal erosions and clinical severity in mice with dextran sulfate sodium-induced colonic injury. This study set out to determine if AMP peptide was also therapeutic for immune- and cytokine-mediated mouse models of intestinal injury and inflammatory bowel diseases by enhancing and stabilizing tight junctions.

METHODS

Therapeutic effects of AMP peptide were examined in interleukin-10-deficient and a T-cell adoptive transfer models of colitis in immunodeficient recombinase activating gene-1 knock-out (RAG-1-/-) mice. Mechanisms by which AMP peptide enhances barrier function and structure were studied ex vivo using intestine and colon from mice given lipopolysaccharide and in AMP-18-deficient mice given dextran sulfate sodium.

RESULTS

In interleukin-10-deficient mice given piroxicam, AMP peptide enhanced recovery after weight loss, protected against colon shortening and segmental dilation, and reduced the colitis activity score. In the T-cell transfer model, treatment with the peptide protected against colon shortening. In mice given lipopolysaccharide in vivo to induce gut injury, AMP peptide prevented the onset of, and reversed established intestinal hyperpermeability by targeting TJ proteins and perijunctional actin. AMP-18-deficient mice challenged with dextran sulfate sodium exhibited increased mortality, developed erosions in the colon, and had lower levels of ZO-1 in TJs than heterozygous littermates or wild-type mice.

CONCLUSIONS

The results indicate that AMP-18/peptide may serve a protective role against injury along the gastrointestinal mucosal barrier, and recommend further development of AMP peptide as a novel agent to treat patients with inflammatory bowel disease.