Regulation of β1-integrin in autophagy and apoptosis of gastric epithelial cells infected with Helicobacter pylori

Helicobacter pylori infection is an essential factor in the development of human gastric diseases, but its pathogenic mechanism is still unclear. In this work we have showed that, the LC3II levels were increased and β1-integrin levels were decreased in H. pylori-positive human gastric tissue samples and H. pylori co-cultured GES-1 cells. There was significant upregulation of LC3II levels and downregulation of P62 levels in GES-1 cells after β1-integrin knockdown co-cultured with H. pylori. This indicated that β1-integrin downregulation promoted autophagy in GES-1 cells after H. pylori infection. The cell apoptosis rate and poly ADP-ribose polymerase (PARP) and caspase-3 activities were increased in GES-1 cells pretreated with 3-methyladenine (3-MA ) after H. pylori infection. Furthermore, there was a significant decrease in apoptosis of β1-integrin knockdown GES-1 cells co-cultured with H. pylori; apoptosis was also downregulated in β1-integrin knockdown- and 3-MA-treated GES-1 cells co-cultured with H. pylori. Correspondingly, PARP and caspase-3 activities were decreased in β1-integrin knockdown cells co-cultured with H. pylori and β1-integrin knockdown-3-MA-treated-1 cells with H. pylori infection. Thus, β1-integrin is a novel autophagy and apoptosis regulator during H. pylori infection. However, inhibition of autophagy did not reverse the decrease in apoptosis caused by downregulation of β1-integrin.

Structural characterization of a polysaccharide from Radix Hedysari and its protective effects against H2O2-induced injury in human gastric epithelium cells

The gastroprotective effects of polysaccharides had become a hot topic in the field of functional polysaccharides research. Three polysaccharides, namely HPS-80-1, HPS-80-2, and HPS-80-3 were purified by DEAE-52 column chromatography. The thermodynamic characteristics, scanning electron microscopy, and Congo red experimental results of the above polysaccharides were greatly distinctive. Then a mature GES-1 oxidative stress cell model induced by H₂O₂ was established to screen out subsequent research subjects. It turned out that HPS-80-1 had a desirable protective effect, which was confirmed by analyses of cell cycle & apoptosis, and oxidative stress-related factors in the cell culture media, and so on. Furthermore, Structural features demonstrated that the backbone of HPS-80-1 appeared to mainly consist of →4)-α-D-Glcp-(1→, →4,6)-β-L-Glcp-(1→, and →6)-α-D-Galp-(1→, with branches at O-1, O-4, and O-6 position consisting of →2,4)-β-D-Rhap-(1→, →1)-α-D-Galp-(4→, and →3,4)-α-D-Manp-(1→. It was speculated that the excellent gastric mucosal protective activity of HPS-80-1 may be due to the high amount of glucose in the backbone. In addition, it was also related to the anti-inflammatory activity and antioxidant bases such as (1 → 4)-Glcp and (1 → 6)-Galp in the structure of HPS-80-1. These findings provide a scientific basis for further utilization of polysaccharides from Radix Hedysari.

Ultrasound and high hydrostatic pressure extractions on antioxidant capacity, antiproliferative and apoptosis effects in gastric cancer cells by lemon extract treatment

The objective of the present study was to investigate the antioxidant and antiproliferative effects of lemon extracts (LE) against human gastric cancer cells (SNU-1) and normal human gastric epithelial cells (GES-1), and their mechanism of inducing cellular death. LE was obtained by three extraction methods: conventional (CE), ultrasound (UAE) and high hydrostatic pressure (HHPE). Experimental results show that the extraction method used to obtain the LE had a significant influence on antioxidant capacity, cellular proliferation, and induction of apoptosis in SNU-1 cells. LE was showed to be cytotoxic with an IC₅₀ of 1747.0 µg mL^-1 and 1704.3 µg mL^-1, as obtained by UAE and HHPE, respectively. In addition, this extract induces apoptosis as evidenced by confocal microscopy. Our findings indicate that LE would be an attractive source of bioactive compounds with antioxidant and antiproliferative capacity and can improve the functional value of food.

Acute and chronic infection of H. pylori caused the difference in apoptosis of gastric epithelial cells

Helicobacter pylori (H. pylori) is one of the most important pathogenic bacteria associated with various gastrointestinal diseases. At present, its apoptotic or antiapoptotic mechanism on gastric epithelial cells remains unknown and needs further illustrated. In this study, acute infection model (H. pylori and GES-1 cells were co-cultured for 24 h at a multiplicity of infection MOI of 100:1) and chronic infection model (GES-1 cells were infected repeatedly every 24 h at a multiplicity of infection MOI of 100:1 for approximately 8 weeks) were established, respectively. the chronic H. pylori infected GES-1 cells underwent a typically morphological change and Western Blot results showed that there was slight decrease in expression of E-cadherin, and obvious increase in expression of Vimentin. Apoptosis of these two models were analyzed by flow cytometry compared with the control cells, meanwhile, apoptosis associated markers (Bcl-xL, Bcl-2, Bax, etc) were detected by Western blot, additional in clinical H. pylori-positive gastric cancer tissues. Results showed that compared with the control cells, acute infection of H. pylori significantly accelerated the apoptosis of GES-1, increased the expression of Bax and Cleaved caspase-3, down-regulated expression of Bcl-xL and Bcl-2. Moreover, an opposite result was found in chronic infection of model and clinical gastric cancer tissues, and enhanced expression of NF-κB p65. Taken together, these findings suggest that H. pylori infection plays differential effects on apoptosis of gastric epithelial cells.

Crocin reverses 1-methyl-3-nitroso-1-nitroguanidine (MNNG)-induced malignant transformation in GES-1 cells through the Nrf2/Hippo signaling pathway

BACKGROUND

Crocin, an active constituent of saffron, has anticancer activity. In this study, we investigated the relationship of Crocin with human gastric epithelial cells induced by 1-methyl-3-nitroso-1-nitroguanidine (MNNG), and explored the underlying mechanism.

METHODS

In vivo, the animal growth and atypical hyperplasia were observed in Sprague-Dawley rats. A cell model was established by treating the human gastric mucosa epithelial cell line GES-1 with MNNG. The effects of Crocin on proliferation, cell cycle, apoptosis, and epithelial-mesenchymal transition (EMT) in GES-1 cells were analyzed using Cell Counting Kit-8, colony formation, flow cytometry, and Transwell assay, respectively. Western blot was used to explore the potential mechanism..

RESULTS

The gastric mucosa of animal model deteriorated obviously, the weight growth rate slowed down, and the atypical hyperplasia of gastric mucosa increased. The GES-1 cells had characteristics of malignant cells such as proliferation, apoptosis, and metastasis ability. It was found that Crocin suppressed the cell proliferation, increased apoptosis, and blocked the cycle arrest in G0/G1 phase simultaneously. Furthermore, Crocin negatively regulated the invasion ability of MNNG-treated GES-1 cells and EMT process. Crocin also increased the expression of nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1), decreased TAZ in MNNG-treated GES-1 cells. Interestingly, Crocin regulated the expression of TAZ and yes-associated protein (YAP) by increasing Nrf2 level, as well as their upstream targets, mercaptopyruvate sulfurtransferase (MST) and large tumor suppressor (LATS).

CONCLUSIONS

Crocin protected against MNNG-induced malignant transformation through the Nrf2/Hippo signaling pathway, which might be a drug candidate for clinical gastric cancer management.

Sterigmatocystin-induced checkpoint adaptation depends on Chk1 in immortalized human gastric epithelial cells in vitro

Sterigmatocystin (ST) is a common contaminant detected in food and animal feed that has been recognized as a possible human carcinogen. Our previous studies demonstrate that ST causes DNA damage and subsequently triggers cell cycle arrest in G₂ and apoptosis in immortalized human gastric epithelial cells (GES-1). Recently, studies have shown that in certain contexts, cells with DNA damage may escape checkpoint arrest and enter mitosis without repairing the damage. The term for this process is "checkpoint adaptation," and it increases the risk of unstable genome propagation, which may contribute to carcinogenesis. Thus, we aimed to investigate whether checkpoint adaptation occurs in GES-1 cells treated with ST and explored the underlying molecular mechanisms that contribute to this phenotype. In this study, we found that ST treatment for 24 h in GES-1 cells led to an initial G₂ arrest; however, a fraction of GES-1 cells became large and rounded, and the number of p-H3-positive cells increased sharply after ST treatment for 48 h. Moreover, collection of the large and rounded cells by mechanical shake-off revealed that the majority of these large cells were found in the mitotic phase of the cell cycle. Importantly, we found that these rounded cells entered mitosis despite damaged DNA and that a small subset of this cell population survived and continued to propagate. These results suggest that ST induces an initial G₂ arrest that is subsequently followed by G₂ phase checkpoint adaptation, which may potentially promote genomic instability and result in tumorigenesis. Furthermore, we showed that activation of Chk1 contributes to the G₂ arrest in GES-1 cells that are treated with ST for 24 h and that prolonged treatment of cells with ST for 48 h led to a decrease in the total protein and phosphorylation levels of Chk1 in mitotic cells, indicating that checkpoint adaptation may be driven by inactivation of Chk1. Knockdown studies confirmed that cells entered mitosis following inactivation of Chk1. Taken together, we show that ST treatment for 24 h activates Chk1 and induces a G₂ arrest in GES-1 cells. However, prolonged ST treatment for 48 h led to Chk1 inactivation in GES-1 cells, which promotes checkpoint adaptation and entry of cells into mitosis despite damaged DNA. Importantly, checkpoint adaptation in GES-1 cells treated with ST may potentially promote genomic instability and drive tumorigenesis.

Mosapride protects against clopidogrel-induced gastric mucosal epithelium cell damage via the p38 MAPK signaling pathway

AIM: To investigate whether mosapride has a protective effect against clopidogrel-induced gastric mucosal epithelium cells (GES-1) damage and to explore the underlying mechanisms.

METHODS: GES-1 cells were cultured in vitro and divided into control group, clopidogrel group (treated with clopidogrel at a concentration of IC50, 0.36 mmol/L) and clopidogrel plus mosapride groups (treated with clopidogrel and 0.4, 0.5, or 0.6 µmol/L of mosapride). MTT assay and flow cytometry were used to detect the proliferation and apoptosis of cells of each group. The expression of phosphorylated P38 (p-P38), occludin and ZO-1 proteins in GES-1 cells was detected by Western blot.

RESULTS: Compared to the control group, p-P38 expression was significantly up-regulated in the clopidogrel group (P < 0.05). The expression of p-P38 in the clopidogrel plus mosapride groups was significantly lower than that in the clopidogrel group (all P < 0.05). With the decrease in p-P38 expression, the expression of occludin and ZO-1 were gradually increased.

CONCLUSION: Mosapride exerts a protective effect against clopidogrel-induced GES-1 cell damage probably by inhibiting p38/MAPK phosphorylation and up-regulating the expression of tight junction proteins occludin and ZO-1.

shRNA-mediated silencing of hexokinase II inhibits proliferation but promotes apoptosis in SGC7901 cells

AIM: To observe the changes in cell proliferation and apoptosis in gastric cancer cell line SGC7901 after silencing the hexokinase II (HK-II) gene with an HK-II-specific shRNA, and to assess the potential application of HK-II-targeted gene therapy for gastric cancer.

METHODS: Gastric cancer cell line SGC7901 and gastric epithelial cell line GES-1 were used in this study. Both SGC7901 cells and GES-1 cells were divided into 5 groups: HK-II shRNA group, positive control group, negative control group, empty liposome group, and blank control group. After transfection of HK-II-specific shRNA into SGC7901 and GES-1 cells, the change in the expression of HK-II mRNA was detected by reverse transcription-polymerase chain reaction (RT-PCR), and the changes in cell proliferation and apoptosis were assessed by MTT assay and flow cytometry, respectively.

RESULTS: The expression level of HK-II mRNA in SGC7901 cells was significantly higher than that in GES-1 cells (t = 12.119, P < 0.01). The expression of HK-II mRNA was obviously silenced after transfection of HK-II-specific shRNA (P < 0.01). HK-II knockdown could significantly inhibit proliferation (F = 159.811, P < 0.01) and promote apoptosis (χ² = 21.324, P < 0.01) in SGC7901 cells, but had no significant effect on proliferation and apoptosis in GES-1 cells (F = 0.704, P = 0.592; χ² = 1.007, P = 0.909).

CONCLUSION: HK-II knockdown significantly inhibits proliferation and promotes apoptosis in SGC7901 cells, but has no significant impact in GES-1 cells. HK-II may be a potential target for the treatment of gastric cancer.

Helicobacter pylori infection induces oxidative DNA damage in human gastric epithelial cell line GES-1 and human gastric cancer cell line SGC-7901

AIM: To investigate whether Helicobacter pylori (H. pylori) infection can induce oxidative DNA damage in human gastric epithelial cell line GES-1 and human gastric cancer cell line SGC-7901.

METHODS: H. pylori was co-cultured with GES-1 and SGC-7901 cells, respectively. The morphological changes of GES-1 and SGC-7901 cells between before and after co-culture were observed. The 8-OHdG expression in the two types of cells was detected by laser scanning confocal microscopy.

RESULTS: H. pylori infection induced oxidative DNA damage in both GES-1 and SGC-7901 cells. The expression levels of 8-OHdG in GES-1 and SGC-7901 cells co-cultured with H. pylori were significantly higher than those in control cells (64.9396 ± 17.8142 vs 32.3010 ± 7.3620 and 102.8344 ± 30.2632 vs 77.1336 ± 32.3223, respectively; both P = 0.000). The extent of 8-OHdG upregulation in GES-1 cells co-cultured with H. pylori was significantly higher than that in SGC-7901 cells co-cultured with H. pylori.

CONCLUSION: H. pylori infection induces oxidative DNA damage in both GES-1 and SGC-7901 cells. This result supports the hypothesis that H. pylori induced-oxidative DNA damage plays a pivotal role in the development of gastric carcinoma in patients with chronic gastritis. GES-1 cell line is superior to SGC-7901 cell line in the study of oxidative damage induced by H. pylori.