Qiyun Tang

Pyruvate Kinase M2 Regulates Apoptosis of Intestinal Epithelial Cells in Crohn’s Disease

BackgroundPyruvate kinase M2 (PKM2), a key glycolytic enzyme, is involved in multiple cellular processes including apoptosis. Recently increased fecal PKM2 has been found in Crohn’s disease (CD), but little is known regarding its function in the pathophysiology of the disease.AimThe intestinal expression of PKM2 and its involvement in CD was investigated.MethodsPyruvate kinase M2 expression in mucosal biopsies from patients with CD and normal controls was detected by immunohistochemistry. A murine model of colitis induced by trinitrobenzenesulphonic acid (TNBS) was established and expression of PKM2, B cell lymphoma-extra large (Bcl-xl), active caspase-3 as well as cleaved poly (ADP-ribose) polymerase (PARP) was examined for association of PKM2 with intestinal epithelial cell (IEC) apoptosis. Furthermore, we treated human IEC line HT-29 by tumor necrosis factor-α (TNF-α) and used RNA interference to analyze the role of PKM2 in IEC apoptosis.ResultsIntestinal expression of PKM2 was higher in patients with CD compared with normal controls mainly locating in IECs. In TNBS-induced colitis, up-regulation of PKM2 was accompanied by the elevated expression of Bcl-xl, active caspase-3, and cleaved PARP. PKM2 was co-localized with active caspase-3 in IECs marked by E-cadherin, suggesting its role in IEC apoptosis. Expression of PKM2 and Bcl-xl in TNF-α-induced HT-29 cells was increased, while TNF-α had no effect on cellular localization of PKM2. Furthermore, knockdown of PKM2 by siRNA could inhibit expression of Bcl-xl but enhance apoptosis in TNF-α-treated HT-29 cells.ConclusionThe up-regulation of PKM2 might protect IECs against apoptosis possibly through Bcl-xl in CD, indicating its important role in the pathophysiology of CD.

SGK1 inhibits cellular apoptosis and promotes proliferation via the MEK/ERK/p53 pathway in colitis.

AIM To investigate the role of serum-and-glucocorticoid-inducible-kinase-1 (SGK1) in colitis and its potential pathological mechanisms. METHODS SGK1 expression in mucosal biopsies from patients with active Crohns disease (CD) and normal controls was detected by immunohistochemistry. We established an acute colitis model in mice induced by 2,4,6-trinitrobenzene sulfonicacid, and demonstrated the presence of colitis using the disease activity index, the histologic activity index and hematoxylin and eosin staining. The cellular events and potential mechanisms were implemented with small interference RNA and an inhibitor of signaling molecule (i.e., U0126) in intestinal epithelial cells (IECs). The interaction between SGK1 and the signaling molecule was assessed by co-immunoprecipitation. RESULTS SGK1 expression was significantly increased in the inflamed epithelia of patients with active CD and TNBS-induced colitis model (0.58 ± 0.055 vs 0.85 ± 0.06, P < 0.01). At the cellular level, silencing of SGK1 by small interference RNA (siSGK1) significantly inhibited the phosphorylation of mitogen-activated protein kinase kinase 1 (MEK1) and the downstream molecule extracellular signal regulated protein kinase (ERK) 1/2, which induced the upregulation of p53 and Bcl-2-associated X protein, mediating the subsequent cellular apoptosis and proliferation in IECs. Cells treated with MEK1 inhibitor (i.e., U0126) before siSGK1 transfection showed a reversal of the siSGK1-induced cellular apoptosis. CONCLUSION Our data suggested that SGK1 may protect IECs in colitis from tumor necrosis factor-α-induced apoptosis partly by triggering MEK/ERK activation.

Epithelial-specific ETS-1 (ESE1/ELF3) regulates apoptosis of intestinal epithelial cells in ulcerative colitis via accelerating NF-κB activation.

Epithelial-specific ETS-1 (ESE1), also named as ELF3, ERT and ESX, belonging to the ETS family of transcription factors, exerts multiple activities in inflammation, epithelial differentiation and cancer development. Previous data demonstrated that ESE1 synergizes with NF-κB to induce inflammation and drive tumor progress, and the nuclear translocation of ESE1 promotes colon cells apoptosis. However, the expression and biological functions of ESE1 in ulcerative colitis (UC) remain unclear. In this study, we reported for the first time that ESE1/ELF3 was over-expressed in intestinal epithelial cells (IECs) of patients with UC. In DSS-induced colitis mouse models, we observed the up-regulation of ESE1/ELF3 accompanied with the elevated levels of IEC apoptotic markers (active caspase-3 and cleaved PARP) and NF-κB activation indicators [phosphorylated NF-κB p65 subunit (p-p65) and p-IκB] in colitis IECs. Increased co-localization of ESE1/ELF3 with active caspase-3 (and p-p65) in IECs of the DSS-induced colitis group further indicated the possible involvement of ESE1/ELF3 in NF-κB-mediated IEC apoptosis in UC. Employing the TNF-α-treated HT-29 cells as an IEC apoptosis model, we confirmed the positive correlation of ESE1/ELF3 with NF-κB activation and caspase-dependent IEC apoptosis in vitro. Immunoprecipitation and immunofluorescence assay revealed the physical interaction and increased nuclear translocation of ESE1/ELF3 and the NF-κB p65 subunit in TNF-α-treated HT-29 cells. Knocking ESE1/ELF3 down by siRNA significantly alleviated TNF-α-induced NF-κB activation and cellular apoptosis in HT-29 cells. Taken together, our data suggested that ESE1/ELF3 may promote the UC progression via accelerating NF-κB activation and thus facilitating IEC apoptosis.

Vacuolar protein sorting 4B regulates apoptosis of intestinal epithelial cells via p38 MAPK in Crohn's disease.

Vacuolar protein sorting 4B (VPS4B), a member of ATPase family proteins, reportedly possesses multiple biological functions, such as regulating the development of breast cancer and non-small-cell lung cancer, participating in Parkinsons disease, and modulating neuronal apoptosis after cerebral ischemia. However, its expression and potential functions in Crohns disease (CD) has not been understood. In this study, we reported for the first time that VPS4B was over-expressed in intestinal epithelial cell (IECs) of patients with CD. In TNBS-induced mouse colitis models, we observed the up-regulation of VPS4B was accompanied with the elevated levels of IEC apoptotic markers (active caspase-3 and cleaved PARP) and phosphorylated p38 in colitis IECs. Co-localization of VPS4B and active caspase-3 in IECs of the TNBS group further indicated the possible involvement of VPS4B in IEC apoptosis. Employing the TNF-α-treated HT29 cells as an in vitro IEC apoptosis model, we confirmed the positive correlation of VPS4B with caspase-dependent cellular apoptosis. Knocking VPS4B down by siRNA significantly alleviated TNF-α-induced p38 phosphorylation and cellular apoptosis in HT29 cells. Taken together, our findings suggested that VPS4B may facilitate the IEC apoptosis in CD via p38 MAPK signaling pathway.

A retrospective study of NENs and miR-224 promotes apoptosis of BON-1 cells by targeting PCSK9 inhibition

Neuroendocrine neoplasms (NENs) represent relatively rare tumors. The lack of diagnostic, therapeutic method and prognostic factors makes them a challenge to us. We retrospectively reviewed the data of 205 NENs patients among which 157 cases were followed-up. Proprotein convertase subtilisin/kexin 9 (PCSK9), a regulator of low density lipoprotein cholesterol (LDL-C), was confirmed as a target gene of microRNA-224. We found an increased incidence of NENs from 2012 to 2015. Women were usually diagnosed at earlier stages than men (P < 0.05). Tumor grading was associated with primary tumor site, especially esophagus and cardia NENs all at G3 (P <0.001). Age, tumor grading and LDL-C levels were independent risk factors of digestive NENs. Low LDL-C level was significantly correlated with survival rate and median overall survival (OS, P < 0.05). MicroRNA-224 agomir and PCSK9 siRNA could promote apoptosis and suppress proliferation, invasion of BON-1 cells (P < 0.05), but increase the level of glucocorticoid (GC, P < 0.05). Taken together, age, tumor grading and LDL-C level are independent risk factors of NENs. The miR-224/PCSK9/GC axis binds to tumorigenesis and prognosis of pancreatic NENs (p-NENs).

PRDM5 promotes the apoptosis of epithelial cells induced by IFN-γ during Crohn’s disease

Elevated apoptosis of intestinal epithelial cells (IECs) greatly impairs the epithelial barrier integrity and contributes to the pathogenesis of Crohns Disease (CD). Overproduction of pro-inflammatory cytokine Interferon-γ (IFN-γ) induces the excessive apoptosis of IECs and is involved in CD development. PRDM5 (PR domain containing 5 PFM2) a member of PRDM family, reportedly acts as a transcriptional regulator involved in tissue specific differentiation and tumor development. In this study, we investigated PRDM5 expression and its potential functions in both human CD (Crohns disease) and TNBS (2,4,6-trinitrobenzenesulfonic acid sol)-induced mice experimental colitis. As shown by western blot and immunohistochemistry, significant up-regulation of PRDM5 was found in the inflamed intestinal tissues of CD patients and TNBS-treated mice, and the molecule was mainly located in IECs. To explore the biological functions of PRDM5 in IEC apoptosis, we established the interferon-γ (IFN-γ) induced cellular apoptosis model on human IEC line HT29 in vitro. IFN-γ significantly increased the expression of PRDM5 in a both time-dependent and concentration-dependent manner in HT29 cells, which was accompanied with an up-regulated expression of apoptotic markers (active caspase-3 and cleaved PARP(poly (ADP-ribpse) polymerase)). Inhibiting PRDM5 expression by siRNA attenuated the IFN-γ-triggered accumulation of active caspase-3 and cleaved PARP in IECs. Moreover, flow cytometry assay and CCK-8 analysis revealed that PRDM5 knockdown significantly alleviated the IFN-γ-induced cellular apoptosis in HT29 cells. Taken together, these data suggest that highly expressed PRDM5 may promote the IFN-γ-induced IEC apoptosis in the progression of CD.

ErbB3 binding protein 1 (EBP1) participates in the regulation of intestinal inflammation via mediating Akt signaling pathway.

ErbB3 binding protein-1 (EBP1) belongs to a family of DNA/RNA binding proteins implicated in cell growth, differentiation and apoptosis. Previous data demonstrated that EBP1 regulates phosphorylation of Akt to drive tumor progress. However, the expression and biological functions of EBP1 in ulcerative colitis (UC) remain unclear. In this study, we reported for the first time that EBP1 was down-regulated in intestinal epithelial cell (IECs) of patients with UC. In DSS-induced colitis, we observed the down-regulation of EBP1 accompanied with the elevated levels of proinflammatory cytokines (IL-1β, IL-6 and IL-8) and Akt activation indicators (phosphorylated Akt) in colitis IECs, indicating the possible involvement of EBP1 in regulation of intestinal inflammation via mediating Akt in UC. Employing the TNF-α-treated HT-29 cells as an IEC inflammatory model, we confirmed the negative correlation of EBP1 with Akt activation and Akt-dependent inflammation progress in vitro. EBP1 knocking down and over-expression significantly regulated TNF-α-induced Akt activation and proinflammatory cytokines expression in HT-29 cells. Taken together, our data suggested that EBP1 participates in the regulation of intestinal inflammation via mediating Akt signaling pathway.

LncNEN885 inhibits epithelial-mesenchymal transition by partially regulation of Wnt/β-catenin signalling in gastroenteropancreatic neuroendocrine neoplasms

It has been shown that long noncoding RNAs (lncRNAs) are involved in the carcinogenesis of multiple cancers. However, the roles of lncRNAs in gastroenteropancreatic neuroendocrine neoplasms (GEP‐NENs) remain elusive. In the present study, we found that lncNEN885 was markedly decreased in human gastric NEN samples compared to adjacent normal tissues by transcriptome sequencing. Functionally, silencing or overexpression of lncNEN885 could not obviously affect cell proliferation or apoptosis in BON‐1 or LCC‐18 cells but could affect cell migration and invasion as well as wound‐healing rates. Furthermore, dysregulation of lncNEN885 affected these biological functions by activating epithelial‐mesenchymal transition through increased expression of Snail, vimentin, and N‐cadherin as well as decreased E‐cadherin levels in BON‐1 and LCC‐18 cells. Silencing of lncNEN885 could dramatically increase the phosphorylation of glycogen synthase kinase‐3β and decrease the expression of adenomatous polyposis coli and Axin, with the subsequent accumulation of β‐catenin. Taken together, dysregulation of lncNEN885 can regulate cell migration and invasion by activating epithelial‐mesenchymal transition process partially through canonical Wnt/β‐catenin signaling in GEP‐NEN cells, which may be a novel biomarker for the metastasis of GEP‐NENs.

Chromosome region maintenance-1 (CRM1) regulates apoptosis of intestinal epithelial cells via p27kip1 in Crohn's disease

OBJECTIVE To investigate the role of chromosome region maintenance-1 (CRM1) in Crohns disease (CD) and its potential pathological mechanisms. METHODS The expression and distribution of CRM1 in mucosal biopsies from patients with active CD and normal controls were detected by immunohistochemistry (IHC). We established a murine model of acute colitis induced by 2,4,6-trinitrobenzene sulfonic acid (TNBS). Western blot was performed to investigate the expression levels of CRM1, apoptotic markers (active caspase-3 and cleaved PARP), p27kip1 and p-p27ser10. IHC was performed to evaluate the distribution of CRM1, and double immunofluorescence (IF) was performed to evaluate the co-localization of CRM1 and active capase-3. Cells of the human intestinal epithelial cell line HT-29 were incubated with tumor necrosis factor-α (TNF-α) to establish an apoptotic in vitro model. Western blot was performed to determine the expression levels of CRM1, active caspase-3, cleaved PARP and p-p27ser10. Cytoplasmic and nuclear extracts were assessed to examine the translocation of CRM1. The interaction between CRM1 and p27kip1 was assessed by co-immunoprecipitation (co-IP) assays. Furthermore, we used small interfering RNA (siRNA) to knock down the protein expression of CRM1 in HT-29 cells and then measured the expression of active caspase-3, cleaved PARP and p-p27ser10. Flow cytometry was used to determine the effect of CRM1 on intestinal epithelial cell (IEC) apoptosis. RESULTS We observed up-regulation of CRM1 accompanied by elevated levels of IEC apoptotic markers (active caspase-3 and cleaved PARP) and p-p27ser10 in IECs of patients with active CD and in TNBS-induced colitis model cells. However, the expression of p27kip1 was negatively correlated with the expression patterns of CRM1, p-p27ser10 and apoptotic biochemical markers. Co-localization of CRM1 and active caspase-3 in IECs of the TNBS group further indicated the possible involvement of CRM1 in IEC apoptosis. By employing TNF-α-treated HT-29 cells as an in vitro IEC apoptosis model, we found that the expression levels of CRM1 and p-p27ser10 were in accordance with active caspase-3 and cleaved PARP. In addition, immunoprecipitation confirmed the physical interaction between CRM1 and p27kip1. siRNA knockdown of CRM1 significantly inhibited the phosphorylation of p27kip1 and the expression of active caspase-3 and cleaved PARP. In addition, flow cytometry analysis also showed that silencing CRM1 by siRNA inhibited TNF-α-induced cellular apoptosis in HT-29 cells. CONCLUSIONS Up-regulated CRM1 may facilitate IEC apoptosis possibly through p27kip1 in CD, indicating an important role of CRM1 in the pathophysiology of CD.