Mass spectrometry-based pseudotargeted metabolomics reveals metabolic variations in a2-induced gastric cancer cell

Gastric cancer (GC) is one of the most malignant tumors with high morbidity and mortality in the world. Compound a2, a Jiyuan oridonin derivative, exhibited excellent anti-proliferative activity against GC cells. To investigate the gastric cellular response to a2 therapy as a novel drug candidate, we adopted a pseudotargeted metabolomics method to explore metabolic variation in a2-induced MGC-803 gastric cells using liquid chromatography tandem mass spectrometry combined with multivariate statistical analysis. The results showed that a2 treatment induced significant metabolic changes in the levels of aminoacyl-tRNA biosynthesis, alanine, aspartate and glutamate metabolism, pyrimidine metabolism, and tricarboxylic acid cycle, approximately 80% of the metabolites were down-regulated in the low-dose and high-dose groups including aspartate, tryptophan, sedoheptulose 7-phosphate, succinate, 2'-deoxyadenosine, uridine, cytidine, etc. which can provide evidence for a new therapy of GC.

[Effect of betulinic acid on proliferation of human gastric cancer MGC-803 cell line]

Objective: To investigate the effect of betulinic acid on the proliferation of human gastric cancer MGC-803 cells in vitro. Methods: Human gastric cancer MGC-803 cells were divided into 4 groups, each with 3 multiple holes. Control cells add betulinic acid at a concentration of 0 μg /ml, and the other three experimental groups were added with final concentration of 10, 20, 30 μg/ml Betulinic acid respectively. Cells in each group were incubated in a 5% CO₂ incubator for 48 hours, and the Giemsa staining method and trypan blue exclusion method were used to detect the effect of betulinic acid on the cell clone formation rate and growth inhibition rate; EdU method and flow cytometry were used to detect cell proliferation and cell cycle changes; qRT-PCR and Western blot were used to detect the expressions of cell cycle regulators CCNB1 and CCND1. Results: Compared with the control group, the clone formation rate of human gastric cancer MGC-803 cells was significantly reduced (P＜0.01), the growth inhibition rate was significantly increased, and the cell proliferation ability was significantly decreased (P＜0.01); with the increase of betulinic acid concentration in each experimental group the proportion of cells in the G1 phase was gradually decreased, and the number of cells in S phase was increased significantly (P＜0.01); the mRNA and protein expression levels of cell cycle regulators CCNB1 and CCND1 were decreased significantly, and the 30 μg/ml betulinic acid treatment group performed best. Conclusion: At a final concentration of 10～30 μg/ml, betulinic acid can reduce the proliferation of human gastric cancer MGC-803 cells, inhibit cell growth, and down-regulate the expression of CCNB1 and CCND1 to block human gastric cancer MGC-803 cells in the S phase.

Compound TDB (Tricyclic decyl benzoxazole) induces autophagy-dependent apoptosis in the gastric cancer cell line MGC-803 by regulating PI3K/AKT/mTOR

OBJECTIVE

Gastric cancer is a potential malignant tumor. Extensive research has shown that apoptosis and autophagy are important mechanisms of cancer pathogenesis. This study aimed to explore the role and mechanism of TDB in apoptosis and autophagy in MGC-803 cells.

METHODS

In cell experiments, the proliferation, apoptosis and autophagy of MGC-803 cells were evaluated by the MTT assay, TUNEL, flow cytometry, MDC, and TEM. Through molecular experiments, the TDB-induced apoptosis and autophagy effects were evaluated by examining the levels of Cleaved-PARP/PARP, Cleaved-caspase3/procaspase3, Beclin-1, p62 and the ratio of LC3-II/LC3-I. At the animal level, the anti-tumor effect of TDB in vivo was evaluated by assessing tumor volume and bioluminescence value.

RESULTS

Regarding mechanism, TDB induces apoptosis and autophagy through PI3K/AKT/mTOR. At the same time, more importantly, TDB promotes 3-methyladenine or autophagy activator rapamycin-mediated. The induced proliferation inhibition and pro-apoptosis effect, which inhibit autophagy and induce an increase in apoptosis.

CONCLUSION

TDB may up-regulate PARP, Cleaved Caspase-3, Beclin1 and LC3B and down-regulate the expression of P62 and other apoptosis and autophagy genes through the activation of PI3K/AKT/mTOR pathway signalling proteins, leading to autophagy-dependent apoptosis. At the animal level, TDB has good anti-tumor efficacy in vivo. In summary, TDB has potential anti-tumor efficacy in vivo and in vitro.

Gamma linolenic acid suppresses hypoxia-induced gastric cancer cell growth and epithelial-mesenchymal transition by inhibiting the Wnt/b-catenin signaling pathway

INTRODUCTION

Gastric cancer is one of the most common malignancies in China and the fifth most common cancer in the world. Gamma linolenic acid (GLA) was reported to have anti-inflammatory and anti-cancer effects. The purpose of this research was to investigate the effect and mechanism of GLA on gastric cancer cell growth under hypoxic conditions.

MATERIAL AND METHODS

The hypoxia models of SGC-7901 and MGC-803 cells were established, and then were exposed to different concentrations of 50, 100 or 200 μM GLA. MTT assay, colony formation assay, wound healing assay and transwell assay were used to investigate the effects of GLA treatment on gastric cancer cell growth under hypoxia (1% O2). The expression of apoptosis- and epithelial-mesenchymal transition (EMT)-related proteins was detected by qPCR and western blot.

RESULTS

GLA treatment significantly decreased viability and inhibited colony formation (p < 0.05, p < 0.01) of SGC-7901 and MGC-803 cells under hypoxia. Western blotting analysis showed that GLA treatment decreased the expression of proliferating cell nuclear antigen (PCNA), microchromosome maintenance complex component 2 (MCM-2) and anti-apoptotic protein Bcl-2, while increased the expression of pro-apoptotic proteins (Bax and Cleaved Caspase-3) (p < 0.05 and p < 0.01). In addition, Wound healing analysis and Transwell assays showed that GLA treatment inhibited the migration and invasion of SGC-7901 and MGC-803 cells in a dose-dependent manner (p < 0.01). Western blotting analysis showed that GLA treatment increased the expression of epithelial marker proteins (g-catenin and E-cadherin), while decreased the expression of stromal and extracellular matrix marker proteins (fibronectin, Snail and b-catenin) (p < 0.01). Further analyses showed that GLA treatment decreased the expression of b-catenin in Wnt/b-catenin pathway (p < 0.01). Moreover, exogenous Wnt3a reversed the inhibitory effect of GLA on b-catenin expression, and further reversed the inhibitory effect of GLA on gastric cancer cell growth and EMT markers (p < 0.05, p < 0.01).

CONCLUSION

These findings suggest that GLA should be tested in animal models and in clinical studies as a potentially effective bioactive phytochemical substance for the treatment of gastric cancer.

BRD9 controls the oxytocin signaling pathway in gastric cancer via CANA2D4, CALML6, GNAO1, and KCNJ5

Background

First-line chemotherapeutic agents lead to remarkable activation treatment in cancers, but the side effects of these drugs also damage healthy cells. In some cases, drug resistance to chemotherapeutic agents is induced in cancer cells. The molecular mechanisms underlying such a side effect have been studied in a range of cancer types, yet little is known about how the adverse effects of chemotherapeutic drugs can be diminished by targeting bromodomain-containing protein 9 (BRD9) in gastric cancers.

Methods

We used two gastric cancer cell lines (MGC-803 and AGS) for comparison. We applied molecular and cellular techniques to measure cell survival and mRNA expression, investigated clinical data in the consensus of The Cancer Genome Atlas, and utilized high-throughput sequencing in MGC-803 cells and AGS cells for global gene expression analysis in inhibiting BRD9 conditions.

Results

Our studies showed that cancer cells with BRD9 overexpression, MGC-803 cells, were more sensitive to BRD9 inhibitors (i.e., BI9564 or BI7273) than AGS cells. The mechanism of BRD9 was related to the regulation of calcium voltage-gated channel auxiliary subunit alpha2 delta 4 (CANA2D4), calmodulin-like 6 (CALML6), guanine nucleotide binding protein (G protein), alpha activating activity polypeptide O (GNAO1) and Potassium Inwardly Rectifying Channel Subfamily J, Member 5 (KCNJ5) oncogenes in the oxytocin signaling pathway. BRD9 inhibitors could enhance the sensitivity of gastric cancer MGC-803 cells to adriamycin and cisplatin, so we may reduce the dosage of chemotherapeutic agents in curing gastric cancers with BRD9 over expression by combining BI9564 or BI7273 with adriamycin or cisplatin.

Conclusions

Our study elucidated the feasibility and effectiveness of inhibiting BRD9 to reduce the adverse effects of first-line chemotherapeutic agents in treating gastric cancer with BRD9 overexpression. This study provides a scientific theoretical basis for a chemotherapy regimen in gastric cancer with BRD9 overexpression.

Synergistic anticancer effect of curcumin and chemotherapy regimen FP in human gastric cancer MGC-803 cells

Curcumin is an anticancer compound that exerts anti-proliferative and apoptotic effects via multiple molecular targets. The purpose of the present study was to investigate the anticancer effects of curcumin in combination with 5-fluorouracil plus cisplatin (FP) on the MGC-803 human gastric cancer cell line. Following treatment with curcumin and/or FP for 24, 48 and 72 h, cell viability, cell cycle progression and the apoptosis rate were evaluated using an MTT assay, flow cytometry and dual acridine orange/ethidium bromide staining, respectively. In addition, colony formation, Transwell migration and caspase-3/caspase-8 activity assays were performed. The expression of the apoptosis regulator B-cell lymphoma-2 (Bcl-2) and Bcl-2-associated X protein (Bax) were detected by western blotting analysis. Following treatment with curcumin and/or FP, cell viability, colony formation and cell migration were significantly reduced compared with the untreated control group. The rate of apoptosis, caspase-3/caspase-8 activity and the expression of Bax were significantly increased, whereas Bcl-2 expression was significantly reduced following treatment with curcumin and/or FP, compared with the untreated control group. The efficacy of curcumin combined with low-dose FP was significantly increased, compared with that of curcumin combined with high-dose FP (P<0.05). Therefore, curcumin may enhance the anticancer effects of FP chemotherapy in MGC-803 cells through the promotion of apoptosis via the caspase-3/caspase-8, Bcl-2 and Bax signaling pathways. These results suggest that curcumin may serve as a synergistic drug with chemotherapy regimen FP for the treatment of gastric cancer.

Lentivirus-mediated E2F-1 gene silencing enhances sensitivity of gastric carcinoma MGC-803 cells to compound ginseng and astragalus

AIM: To observe the effect of recombinant lentivirus-mediated E2F-1 gene silencing on sensitivity of gastric carcinoma MGC-803 cells to compound ginseng and astragalus.

METHODS: MGC-803 cells were plated and divided into four groups: a normal control group (medicine medium), a blank control group, a negative LV-RNAi control group (medicine medium + infection with empty lentiviral vector particles 2.0 × 10⁹ TU/mL) and an E2F-1-RNAi-LV group (medicine medium + infection with recombinant E2F-1 lentiviral particles 2.0 × 10⁹ TU/mL). The mRNA and protein expression levels of E2F1 were detected by RT-PCR and Western blot. Cell proliferation was detected by MTT assay. Cell colony formation was detected by Giemsa staining. Cell apoptosis was observed by flow cytometry, and cell migration was detected by cell scratch assay.

RESULTS: Infection with the recombinant lentiviral vector significantly decreased the protein and mRNA expression levels of E2F-1 compared to the two control groups (0.384 ± 0.036 vs 0.883 ± 0.051 and 0.923 ± 0.049, 0.220 ± 0.056 vs 0.729 ± 0.021 and 0.712 ± 0.037, P < 0.05). Compound ginseng and astragalus inhibited MGC-803 cell growth, induced cell apoptosis, and reduced cell colony formation and migration. Compared to the two control groups, the rates of reduced cell colony formation and cell apoptosis were significantly increased and the areas of cell colony formation and migration were significantly decreased in the E2F-1 gene silencing group (0.789 ± 0.013 vs 0.484 ± 0.060 and 0.454 ± 0.006, 0.383 ± 0.027 vs 0.114 ± 0.038 and 0.089 ± 0.051, 0.024 ± 0.003 vs 0.036 ± 0.004 and 0.052 ± 0.002, 0.553 ± 0.038 vs 0.897 ± 0.020 and 0.928 ± 0.051, P < 0.05).

CONCLUSION: Recombinant lentivirus-mediated E2F-1 gene silencing effectively enhances the sensitivity of MGC-803 cells to compound ginseng and astragalus.

Photoactivaed curcumin inhibits cell growth and promotes apoptosis in human gastric cancer cell line MGC-803

AIM: To investigate the effect of photoactivated curcumin on cell growth and apoptosis in human gastric cancer cell line MGC-803 and to analyze its intracellular distribution.

METHODS: After MGC-803 cells were treated with 5.0 μmol/L of photoactivated curcumin for different durations (12, 24 and 48 h), cell growth was assessed by MTT assay; apoptosis was determined by flow cytometry; nuclear morphological changes were detected by fluorescence microscopy; and the distribution of intracellular curcumin was examined by confocal laser microscopy.

RESULTS: The reduced rates of cell growth were 35.53% ± 3.52%, 40.17% ± 2.01% and 44.93% ± 3.61% in MGC-803 cells treated with photoactivation curcumin for 12, 24 and 48 h, and the apoptosis rates were 20.32% ± 3.07%, 22.46% ± 1.51% and 26.58% ± 2.67%. Compared to the control group, the reduced rates of cell growth were significantly lower and apoptosis rates were significantly higher in the photoactivation curcumin group at all time points (all P < 0.05). Obvious apoptotic bodies were observed after treatment with photoactivated curcumin for 48 hours. Photoactivated curcumin was mainly distributed in the cell membrane and nuclear membrane. Scattered distribution of photoactivated curcumin was noted in other subcellular structures.

CONCLUSION: Photoactivated curcumin can inhibit growth and promote apoptosis of gastric cancer cells in a time-dependent manner. Photoactivated curcumin is mainly located in the plasma membrane and nuclear membrane and sporadically in other subcellular structures.

Celecoxib inhibits the growth of gastric cancer cells not expressing COX-2 in vitro

AIM: To investigate whether celecoxib, a selective cyclooxygenase-2 (COX-2) inhibitor, can induce the apoptosis of human gastric cancer MGC-803 cells not expressing COX-2 and explore potential mechanisms involved.

METHODS: Cell proliferation was measured by methyl thiazolyl tetrazolium (MTT) assay. Cell cycle distribution was measured by flow cytometry. The expression of Bax and Bcl-2 proteins was detected by immunohistochemistry. The secretion of vascular endothelial growth factor (VEGF) protein was detected by enzyme-linked immunosorbant assay (ELISA). The expression of COX-2 and nuclear factor-κB (NF-κB) proteins was examined by Western blot.

RESULTS: The expression of COX-2 protein was not detected in MGC-803 cells. Celecoxib could inhibit the proliferation and induce the apoptosis of MGC-803 cells in a dose- and time-dependent manner. The reduced rates of growth in cells treated with celecoxib at concentrations of 25, 50, 75 and 100 μmol/L for 24 h were 48.4%, 54.9%, 58.69% and 63.80%, respectively. Flow cytometry analysis showed that the apoptotic rate of MGC-803 cells treated with celecoxib was 4%, and a sub-G1 cell peak was present. Celecoxib inhibited the secretion of VEGF protein in MGC-803 cells. With the prolongation of the duration of incubation with celecoxib, the level of secreted VEGF decreased. Celecoxib could also inhibit the secretion of NF-κB protein by inhibiting its expression in a time-dependent manner.

CONCLUSION: Celecoxib inhibits growth and induces apoptosis of MGC-803 cells in a COX-2-independent manner. Celecoxib exerts its antitumor effects possibly by inhibiting the expression of NF-κB protein.