Selection of two intrathoracic anastomosis methods for transabdominal radical surgery for Siewert type II adenocarcinoma of the esophagogastric junction.

Introduction: The most common intrathoracic anastomosis techniques for Siewert type II adenocarcinoma of the esophagogastric junction (AEG) are the overlap and transorally inserted anvil (OrVil) methods. However, the criteria for choosing between these two methods require further study. Aim: This retrospective study aimed to compare the efficacy and safety of overlap versus OrVil anastomosis in transabdominal radical surgery for Siewert type II adenocarcinoma of the esophagogastric junction. Material and methods: A total of 34 patients with Siewert type II AEG who underwent transabdominal radical surgery and intrathoracic anastomosis with the overlap or OrVil methods at our center from January 2018 to June 2019 were retrospectively analyzed. The relevant surgical and postoperative complication data of the two groups were collected and analyzed. Results: Clinical characteristics: the mean tumor size was 7.5 ±2.4 cm in the OrVil group and 4.3 ±1.9 cm in the overlap group (p < 0.05). Surgery: the distance from the upper resection margin of the esophagus to the tumor was 3.2 ±0.84 cm in the OrVil group and 2.4 ±0.6 cm in the overlap group (p < 0.05). Postoperative complications: there were two cases of pleural effusion in the OrVil group and 18 cases of pleural effusion in the overlap group (p < 0.05). Conclusions: There is no significant difference between the OrVil and overlap anastomosis in terms of the feasibility and safety; however, OrVil anastomosis can provide a higher margin of resection of the esophagus and is suitable for tumors with extensive esophageal invasion.

The role of hypoxia-inducible factor 1-alpha in inflammatory bowel disease.

Inflammatory bowel disease (IBD) develops as a result of a combination of genetic predisposition, dysbiosis of the gut microbiota, and environmental influences, which is mainly represented by ulcerative colitis (UC) and Crohn's disease (CD). IBDs can result in inflammatory hypoxia by causing intestinal inflammation and vascular damage. The hypoxia-inducible factor 1-alpha (HIF-1α), as a transcription factor, can regulate the cellular adaptation to low oxygen levels and support the development and function of the gut barrier. HIF-αplays its functions through translocating into the nucleus, dimerizing with HIF-1ß, and binding to hypoxia-responsive elements of HIF-1 target genes. So far, most studies have addressed the function of HIF-1α in murine models of IBD. In this review, we aim to outline the major roles of HIF-1α in the IBD.

Mutual regulation between butyrate and hypoxia-inducible factor-1α in epithelial cell promotes expression of tight junction proteins.

Inflammatory bowel disease is a kind of multi-aetiological chronic disease that is driven by multidimensional factors. Hypoxia-inducible factor-1α (HIF-1α) plays an important role in anti-inflammatory and cellular responses to hypoxia. Previous studies have found that B or T-cell-specific HIF-1α knock out mice exhibit severe colonic inflammation. However, we know very little about other functions of HIF-1α in intestinal epithelial cells (IECs). In our study, HIF-1αΔIEC mice were used to study the function of HIF-1α in IECs. HIF-1α was knocked down in Caco-2 cells by transfection with a small interfering (si) RNA. Immunohistochemical staining and western blotting were used to detect the expression of zonula occluden-1 (ZO-1) and Occludin. The content of colon was harvested for high-performance liquid chromatography analysis to examine the levels of butyrate in the gut. Our research found that HIF-1α played a protective role in dextran sulphate sodium-induced colitis, which was partly due to its regulation of tight junction (TJ) protein expression. Further study revealed that HIF-1α mediated TJ proteins levels by moderating the content of butyrate. Moreover, we found that butyrate regulated TJ protein expression, which is dependent on HIF-1α. These results indicated that there is a mutual regulatory mechanism between butyrate and HIF-1α, which has an important role in the maintenance of barrier function of the gastrointestinal tract.

Aryl hydrocarbon receptor activation alleviates dextran sodium sulfate-induced colitis through enhancing the differentiation of goblet cells.

BACKGROUND: The intestinal inflammation induces disruption of the intestinal barrier function and leads to bacteria invasion. Accumulating evidences revealed that the aryl hydrocarbon receptor (AhR) plays a vital role in maintaining the intestinal barrier function. However, the precise mechanism remains to be unclear. METHODS: Adult C57BL/6J mice were randomly divided into three groups: Sham, DSS and DSS + 6-formylindolo (3, 2-b) carbazole (FICZ)group. The colons and epithelial cell were harvested for histological examination, pro-inflammatory cytokines detection, bacterial load analysis, immunohistochemistry and Muc2 protein analysis. Under physiological condition, AhRKO model and FICZ treatment were used to evaluate the roles of AhR in the differentiation of goblet cells and the expression of Muc2 in mice. In vitro, we used HT29 mol to research the signaling pathway. RESULTS: AhR activation by FICZ could increase the Muc2 expression and the number of goblet cells and reduce bacterial infiltration to ameliorate DSS-induced Colitis. Under physiological conditions, the treatment of FICZ promote the differentiation of goblet cell and the expression of Muc2 and inhibit the notch-signaling. Genetic deletion of AhR led to the loss of goblet cells and the decrease of Muc2 expression and enhance the notch-signaling. In HT29 cells, the differentiation of goblet cell meditated by AhR can be abolished by the inhibitor of AhR, pErk1/2 and knocking-down AhR. CONCLUSION: FICZ promoted the differentiation of goblet cell through AhR-pErk1/2 signaling pathway and ameliorate DSS-induced Colitis.

The protective roles of NLRP6 in intestinal epithelial cells.

The evolution of chronic inflammatory diseases is thought to be due to a combination of host genetic variations and environmental factors that include the alteration of intestinal flora, termed "dysbiosis." The intestinal mucosal barrier includes a chemical barrier and physical barrier that have important roles in protecting the intestine against inflammatory injury. The chemical barrier includes antimicrobial peptides (AMPs), and the physical barrier includes a mucous layer, a monolayer of intestinal epithelial cells and cell junctions. The intestinal mucosal barrier is not a static barrier, but rather, it strongly interacts with the gut microbiome and cells of the immune system. Correct expression of AMPs, together with mucus and balanced epithelial cell proliferation, prevents the occurrence of disease. NLRP6, a member of the nucleotide-binding domain, leucine-rich repeat-containing (NLR) innate immune receptor family, participates in the progression of intestinal inflammation and enteric pathogen infections. It has become apparent in recent years that NLRP6 is important in disease pathogenesis, as it responds to internal ligands that lead to the release of AMPs and mucus, thus regulating the regeneration of intestinal epithelial cells. This review summarizes the activation of NLRP6 and its protective role in the intestinal epithelial cell.

Aryl hydrocarbon receptor inhibits inflammation in DSS­induced colitis via the MK2/p­MK2/TTP pathway.

The pathogenesis of inflammatory bowel disease (IBD) is believed to be associated with the abnormal expression of inflammatory factors. The aryl hydrocarbon receptor (AhR) is a ligand­dependent transcription factor, which can suppress the inflammatory response and attenuate experimental colitis. However, the detailed mechanism underlying the effects of AhR remains unclear. The present study investigated the role of AhR in the pathogenesis of IBD. Colitis was induced in mice by administration of 3% dextran sulphate sodium (DSS) for 7 days. The mice were also administered injections of the AhR agonist, 6­formylindolo(3,2­b)carbazole (FICZ), starting 2 days after the first administration of DSS. Furthermore, LoVo cells were treated with lipopolysaccharide (LPS) in the presence or absence of FICZ for 8 h. The protein expression levels of AhR, cytochrome P450 1A1 (CYP1A1) and tristetraprolin (TTP) were assessed by western blotting and immunofluorescence, whereas mRNA expression levels were assessed by reverse transcription­quantitative polymerase chain reaction. The results indicated that injection of mice with FICZ significantly attenuated DSS­induced colitis; in addition, the expression levels of inflammatory cytokines were markedly downregulated. Conversely, the expression levels of AhR and TTP were upregulated. In addition, mice in the AhR­knockout + DSS group exhibited elevated inflammatory cytokine production and developed more severe colitis. In LoVo cells, incubation with FICZ decreased the expression levels of inflammatory cytokines, whereas AhR and TTP expression was increased. In addition, the levels of phosphorylated­mitogen­activated protein kinase­activated protein kinase 2 (p­MK2) were decreased. These results suggested that AhR deficiency resulted in increased susceptibility to colitis, whereas activation of AhR by FICZ could ameliorate DSS­induced colitis via the MK2/p­MK2/TTP pathway.

AhR­E2F1­KGFR signaling is involved in KGF­induced intestinal epithelial cell proliferation.

Keratinocyte growth factor (KGF) stimulates intestinal epithelial cell proliferation upon binding to the KGF receptor (KGFR). The activated aryl hydrocarbon receptor (AhR) serves an important role in the development of tissues by promoting the expression of AhR receptors, which can regulate cell proliferation. In the present study, the signaling pathway between AhR and KGFR in investigated with regards to KGF­induced intestinal epithelial cell proliferation. Male C57BL/6J wild type and AhR­/­ mice, were randomized into four groups: Control, KGF, AhR­/­ + KGF and AhR­/­ (n=6 per group). The small bowel was harvested on day 5 post­treatment. LoVo cells were used to study signaling pathways in vitro and were divided into the following four treatment groups: DMSO, KGF, KGF + small­interfering (si)AhR and siAhR. In vivo, knockdown of AhR mRNA transcripts may abolish KGF­induced intestinal epithelial cell proliferation. Furthermore, KGFR expression was downregulated following knockdown or silencing of AhR expression in vivo and in vitro. The present study identified that the transcription factor E2F1 could regulate KGFR expression, and that siAhR treatment led to reduced expression of E2F1 in the nucleus and inhibited KGF­induced cell proliferation. In conclusion, the current results demonstrated that the AhR­E2F1­KGFR pathway is involved in KGF­induced intestinal epithelial cell proliferation.

Role of AhR in positive regulation of cell proliferation and survival.

The aryl hydrocarbon receptor (AhR) is an important nuclear transcription factor that is best known for mediating toxic responses by adjusting numbers of metabolism-related enzymes, including CYP1A1 and CYP1B1. Previous findings have revealed that, in addition to negatively regulating cell proliferation and survival, AhR may also positively regulate these pathways. Here, we review these findings and summarize distinct mechanisms by which AhR promotes cell proliferation and survival, including modulation of receptor expression, growth factor signalling and apoptosis, regulating the cell cycle and promoting cytokine expression. This review will aid better understanding the role of AhR in positive regulation of cell proliferation and survival.

Aryl Hydrocarbon Receptor Activation in Intestinal Obstruction Ameliorates Intestinal Barrier Dysfunction Via Suppression of MLCK-MLC Phosphorylation Pathway.

BACKGROUND: Accumulating evidence suggests that the aryl hydrocarbon receptor (AhR) plays an important role in the maintenance of the function of the intestinal barrier in patients with inflammatory bowel disease and in mouse models. Intestinal obstruction (IO) is a clinical emergency consisting of severe dysfunction of intestinal barrier function, and whether AhR plays a role in the pathogenesis of IO remains unknown but would be highly significant. METHODS: Male C57BL/6 mice were subjected to IO and either treated with AhR endogenous agonist 6-formylindolo [3, 2-b] carbazole (FICZ) or left untreated. Intestinal tissue was harvested after 24 h. Correspondingly, Caco-2 monolayers were treated with FICZ in the absence or presence of hypoxia in vitro or left untreated. The cells were used after 12 h. RESULTS: Damage to the intestinal mucosa was anabatic and intestinal permeability was significantly higher in murine IO and hypoxia-induced Caco-2 models than in controls. Under these conditions the activity of AhR was lower and the fluorescence of zonula occludens-1 (ZO-1) was absent. The increased expression of myosin light chain kinase (MLCK) and phosphorylated MLC (pMLC) indicated that this pathway was open. However, treatment with FICZ caused retention of the tight junction protein ZO-1, alleviated the increase of intestinal permeability, and mitigated epithelial injury. Depletion of AhR by AhR small interfering RNA facilitated the unblocking of the MLCK-pMLC signaling pathway and repressed the protein expression of ZO-1 in vitro. CONCLUSION: AhR activation can ameliorate epithelial barrier dysfunction induced by IO through the suppression of MLCK-pMLC signaling, suggesting that AhR agonist may be a suitable means of addressing this condition.

The AhR is involved in the regulation of LoVo cell proliferation through cell cycle-associated proteins.

Some ingredients in foods can activate the aryl hydrocarbon receptor (AhR) and arrest cell proliferation. In this study, we hypothesized that 6-formylindolo [3, 2-b] carbazole (FICZ) arrests the cell cycle in LoVo cells (a colon cancer line) through the AhR. The AhR agonist FICZ and the AhR antagonist CH223191 were used to treat LoVo cells. Real-time PCR and Western blot analyses were performed to detect the expression of the AhR, CYP1A1, CDK4, cyclinD1, cyclin E, CDK2, P27, and pRb. The distribution and activation of the AhR were detected with immunofluorescence. A 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) assay and flow cytometric analysis were performed to measure cell viability, cell cycle stage, and apoptosis. Our results show that FICZ inhibited LoVo cell proliferation by inducing G1 cell cycle arrest but had no effect on epithelial apoptosis. Further analysis found that FICZ downregulated cyclinD1 and upregulated p27 expression to arrest Rb phosphorylation. The downregulation of cyclinD1 and upregulation of p27 were abolished by co-treatment with CH223191. We conclude that the AhR, when activated by FICZ (an endogenous AhR ligand), can arrest the cell cycle and block LoVo cell proliferation.

Keratinocyte Growth Factor Regulation of Aryl Hydrocarbon Receptor Activation in Colorectal Cancer Cells.

BACKGROUND: Keratinocyte growth factor (KGF) stimulates normal growth, development and intestinal epithelial cell proliferation. Cyclin D1 promotes the cell cycle by inhibiting retinoblastoma protein (RB1). The activated aryl hydrocarbon receptor (AhR) has an important influence on the development of tumors through its interactions with the cell cycle. AIM: The aim of the present study was to explore a new role for AhR in KGF-induced colon cancer cell growth. MATERIALS AND METHODS: Real-time PCR, western blot or immunofluorescence analysis were used to detect the expression of KGF, AhR, cyclin D1 and CYP1A1. Immunohistochemistry was used to observe the localization of AhR. MTT assay and flow cytometric analyses were performed to measure cell viability and the cell cycle. RESULTS: Real-time PCR analysis revealed that KGF, AhR, and CYP1A1 mRNAs were overexpressed in colorectal cancer tissues. Meanwhile, overexpression of AhR was primarily observed in epithelial cells. In in vitro assay, KGF promoted colon cancer cell growth, as well as up-regulated and activated AhR. At the same time, AhR-knockdown colon cancer cells were less responsive to KGF. Western blot analysis, real-time PCR, or immunofluorescence data indicated that cyclin D1 expression was up-regulated by KGF but this up-regulation was compromised when AhR was silenced, and the cell cycle was arrested in the G0/G1 stage in these cells. CONCLUSIONS: Our study suggests that KGF, AhR, and CYP1A1 are overexpressed in colorectal cancer tissues. Moreover, we reveal a new mechanism by which KGF promotes cell proliferation through the AhR-cyclin D1 pathway in colon cancer cells.