Advances in gastric cancer prevention

Nutritional Factors Involved in the Etiology of Gastric Cancer: A Systematic Review

CONTEXT

Since treatment options for GC are limited, the best and most effective way is to try to reduce the incidences and understanding prevention strategies.

OBJECTIVE

The success in prevention strategies depends on understanding etiologic mechanisms. Our goal is to identify the major nutritional risk factors for GC, and we will examine the controversial evidence.

DATA SOURCES

We used Pub Med, Google Scholar, Scopus, Science Direct, Elsevier, Springer, and MEDLINE databases for extracting articles.

DATA EXTRACTION

Human studies published in English from 1997to2018 were included. Two reviewers other than authors initially assessed abstract of 742 papers and 248papers were selected for future assessments. After full review and consideration of the inclusion and exclusion criteria, we used 85 articles.

RESULTS

Dietary salt is a strong independent risk for GC whereas alcohol is most likely a risk only in the presence of heavy alcohol consumption. Red meat and high-fat diet increase the risk of developing GC but fresh fruits, vegetables and certain micronutrients like selenium and vitamin C are protective.

CONCLUSION

Some nutrients such as selenium, vitamin C, folate, iron, and zinc are involved in the etiology of GC. On the other hand; salt, fats, alcohol, red meat, and pepper were reported to be risk factors for GC. Since the GC is a heterogeneous malignancy and multiple factors are involved in its genesis.

Portal vein tumor thrombus from gastric cancer

A 53-year-old woman presented with left-sided abdominal pain, nausea and vomiting for the past 3 months with associated loss of appetite and weight. On physical examination, there was a large, ill-defined, firm mass at the epigastrium. Ultrasonography showed heterogeneously hypoechoic filling defect within the dilated main portal vein. The filling defect showed florid signals on Doppler mode and it appeared to be an extension of a larger periportal mass. Contrast enhanced abdominal computed tomography confirmed a large distal gastric mass infiltrating into the periportal structures, including the main portal vein and the splenic vein. Esophagogastroduodenoscopy performed 2 days later showed an irregular, exophytic mass extending from the antrum into the first part of duodenum. The mass was deemed inoperable. Histopathological examination showed gastric adenocarcinoma. She was started on anticoagulant, chemotherapy and pain management. Follow-up computed tomography 4 months later showed liver metastases and formation of collateral blood vessels.

Anticancer activity of tetrandrine by inducing pro-death apoptosis and autophagy in human gastric cancer cells

OBJECTIVES

To investigate the antitumour property of tetrandrine by inducing autophagy and apoptosis in human gastric cancer cells, and to explore the potential molecular mechanisms.

METHODS

The antitumour activity of tetrandrine was assessed through MTT assay. Apoptosis was measured by flow cytometry and microscopic examination of cellular morphology. The mitochondrial membrane potential was detected by staining with Rh-123. Induction of autophagy was monitored by transmission electron microscopy observation, using GFP-LC3 transfection.

KEY FINDINGS

The results revealed that tetrandrine exhibits significant antitumour activity against gastric human cancer cell and the antigastric tumour activity was depended on inducing autophagy and apoptosis through upregulating the apoptosis-related protein (cleaved PARP, cleaved caspase-3 and cleaved caspase-9) and autophagy-related protein (Beclin-1, LC3-II and p62), and decreasing the phosphorylation of AKT/mTOR, PS6K and P-4EBP1. Adding the inhibitor of autophagy, 3-MA or Baf-A1, increased the viability of tetrandrine-exposed gastric cancer cells, which confirmed the role of autophagy played in the gastric cancer cell death induced by tetrandrine.

CONCLUSIONS

These results demonstrated that the antitumour effects of tetrandrine by inducing autophagy and apoptosis involving Akt/mTOR pathway. Thus, tetrandrine may be a promising lead compound to be further developed in future for cancer therapy.

Pachymic acid inhibits growth and induces cell cycle arrest and apoptosis in gastric cancer SGC-7901 cells

The aim of the present study was to elucidate the anticancer effect of pachymic acid (PA) in gastric cancer SGC-7901 cells and the potential molecular mechanisms involved. Cell Count kit-8 assay was performed to examine the effect of PA on the cell proliferation of SGC-7901 cells. Cell cycle, cell apoptosis, mitochondria membrane potential (Dψm) and reactive oxygen species (ROS) analysis were assessed by flow cytometry, respectively. DNA fragmentation assay was performed by Hoechst 33258 staining. Western blotting was performed to detect the effect of various concentrations of PA on the levels of BCL2 associated X protein (Bax) expression as well as B-cell lymphoma 2 (Bcl-2), cytochrome C (cyt-c) and caspase-3 in SGC-7901 cells. It was demonstrated that PA was able to significantly inhibit the viability and induce G₀/G₁ cell cycle arrest of SGC-7901 cells in a concentration-dependent manner. The apoptotic rate and ROS generation were markedly increased, while Dψm was decreased following the treatment of SGC-7901 cells with various concentrations of PA. Moreover, the expression of Bax, cytochrome c and caspase-3 were markedly increased and Janus kinase 2 (JAK2)/signal transducer and activator of transcription 3 (STAT3) was significantly inactivated and BCL-2 expression was decreased following PA treatment in SGC-7901 cells. Notably, JAK2 inhibitor (AG490) mimics the effects of PA on the viability and apoptosis of SGC-7901 cells. Further in vivo study indicated that treatment with PA significantly inhibited the growth of tumor in nude mice that were transplanted with SGC-7901 cells in a concentration-dependent manner. These results may advance the current understanding of the anticancer mechanisms of PA in gastric cancer.

Effect of dimerized melittin on gastric cancer cells and antibacterial activity

Melittin is the peptide toxin found in bee venom and is effective against cancer cells. To enhance its activity, a branched dimeric form of melittin was designed. The monomeric form of the peptide was more cytotoxic against gastric cancer cells at low concentrations (1-5 μM) than the dimer form, while the cytotoxic effect was comparable at higher concentrations (10 μM). Confocal microscopy showed that both the monomer and dimer forms of melittin with fluorescent label at the C terminus penetrated the cytoplasm and localized at the cell nucleus and disrupted the cell membrane. The results indicated that both peptides localized in the nucleus and no significant difference in penetration was observed between monomer and dimer of melittin. Although the C and N termini are important for melittin activity, using C terminus for dimerization of the peptide resulted in similar activity for the monomer and dimer against bacteria and gastric cancer cells.

MicroRNA-200c regulates cisplatin resistance by targeting ZEB2 in human gastric cancer cells

This study was specifically designed to confirm the hypothesis that microRNA-200c (miR-200c) affects the development of cisplatin (DDP) resistance in human gastric cancer cells by targeting zinc finger E-box binding homeobox 2 (ZEB2). A total of 50 gastric cancer tissues and their corresponding normal adjacent tissue samples were collected. Then, the expression levels of miR-200c and ZEB2 in both gastric cancer specimens and cells were detected using the quantitative real-time reverse transcription-polymerase chain reaction (qRT-PCR) and immunohistochemical methods. A dual‑luciferase reporter gene assay was conducted to evaluate the effect of miR-200c on the 3'-untranslated region (3'UTR) luciferase activity of ZEB2. SGC7901/DDP cells were transfected with miR-200c mimics and ZEB2 siRNA, respectively. Subsequently, changes in cellular proliferation and apoptosis were detected through the methyl thiazolyl tetrazolium assay and flow cytometric analysis, respectively. We also carried out a western blot analysis assay in order to detect the expression of apoptosis-related genes and ZEB2. miR-200c was significantly downregulated and ZEB2 was significantly upregulated in both gastric cancer tissues and SGC7901/DDP cells when compared with those in normal tissues and SGC7901 cells (P<0.01). The dual luciferase reporter gene assay showed that miR-200c could specifically bind with the 3'UTR of ZEB2 and significantly suppress the luciferase activity by 42% (P<0.01). Upregulation of miR-200c or downregulation of ZEB2 enhanced the sensitivity of SGC7901/DDP cells to DDP. miR‑200c was significantly downregulated in both gastric cancer tissues and cells, while the expression of ZEB2 exhibited the opposite trend. Our study further demonstrated that miR-200c could enhance the sensitivity of SGC7901/DDP cells to DDP through targeted regulation of ZEB2 expression in gastric cancer tissues.

Efficacy of Omega Fatty Acid Supplementation on mRNA Expression Level of Tumor Necrosis Factor Alpha in Patients with Gastric Adenocarcinoma

PURPOSE

Tumor necrosis factor alpha (TNF-α), a multifunctional cytokine, is involved in apoptosis, cell proliferation, cell survival, and inflammation. It plays a dual role in cancer development and progression. It has been revealed that polyunsaturated fatty acids (PUFAs) modulate the production and activity of TNF family cytokines. The objective of the present study was to evaluate the effect of PUFAs on messenger RNA expression levels of TNF-α in patients with gastric adenocarcinoma.

METHODS

Thirty-four chemotherapy-naive patients diagnosed with gastric adenocarcinoma were randomly divided into two groups. The first group (17 individuals) received cisplatin without supplements and the second group (17 individuals) received cisplatin plus orally administered PUFA supplements for 3 weeks, based on treatment strategies. The gastric biopsy samples were obtained from all participants before and after treatment, and TNF-α mRNA expression levels were evaluated by quantitative real-time PCR procedure.

RESULTS

Our findings revealed that TNF-α mRNA expression is downregulated in group II, after receiving cisplatin and omega fatty acid supplement for 3 weeks. However, this difference is not statistically significant (p > 0.05). TNF-α mRNA expression did not show significant alteration in group I, after receiving cisplatin alone.

CONCLUSIONS

Taken together, we concluded that omega fatty acids reduce TNF-α expression at the mRNA level in patients with gastric adenocarcinoma. These data suggest that TNF-α may act as a potential target for the therapy of human gastric adenocarcinoma.

The role of antiangiogenic agents in the treatment of gastric cancer: A systematic review and meta-analysis

BACKGROUND

The survival of advanced gastric cancer (GC) is dismal, and effects of antiangiogenic agents remain inconclusive. The purpose of this study is to assess combination of chemotherapy with antiangiogenic therapy versus traditional chemotherapy.

METHODS

To achieve the goal of scientific rigor, statistics from both referenced works and experiments were analyzed. We carefully searched for the referenced works by retrieving, as well as analyzing, literature databases for information on antiangiogenic therapy compared to other therapeutic approaches used to treat GC patients. Two groups were defined in the experiment: experimental and control groups. The experimental group was treated with antiangiogenic drug, and the control group was treated with standard chemotherapy or placebo.

RESULTS

The study included a total of 3240 participants. Overall, there was significant improvement in overall survival (hazard ratio [HR] = 0.78, 95% confidence interval [CI]: 0.67-0.91, P = 0.002), progression-free survival (HR 0.65, 95% CI: 0.52-0.81, P = 0.0002), objective response rate (risk ratio [RR] = 1.58, 95% CI: 1.33-1.88, P < 0.00001), and disease control rate (RR 2.44, 95% CI: 1.57-3.78, P < 0.0001) in the group with antiangiogenic drug versus the group with standard chemotherapy or placebo. Moreover, this new treatment approach showed tolerable toxicity.

CONCLUSION

This study confirms the superior efficacy of combination therapy with antiangiogenic agents in comparison to traditional chemotherapy regimens for patients with GC. Moreover, this new treatment approach showed tolerable toxicity. This meta-analysis provides important information for clinicians who are interested in using antiangiogenic therapies to treat GC patients.

RASSF1A inhibits gastric cancer cell proliferation by miR-711- mediated downregulation of CDK4 expression

Although interaction with DNA repair proteins has demonstrated that RASSF1A is a tumour suppressor gene, much attention has been directed in recent years towards its roles in regulating the cell cycle. However, the precise mechanism remains unclear. Uncovering how RASSF1A participates in regulating the cell cycle is critical to exploring effective therapeutic targets for gastric cancer. Here we show that RASSF1A could regulate 14 miRNAs’ expression in the typical human gastric cancer line SGC-7901, of which miR-711 was upregulated the most. Moreover, for SGC-7901 cells, miR-711 was found to downregulate CDK4 expression, and to arrest the cell cycle in the G1 phase. Our results suggest that RASSF1A inhibits the proliferation of gastric cancer cells by upregulating the expression of miR-711, which arrested gastric cancer cells in the G1 phase by downregulating expression of CDK4. This finding might provide us with a novel therapeutic target for gastric cancer by increasing RASSF1A expression via miR-711 regulation.

Melittin induces human gastric cancer cell apoptosis via activation of mitochondrial pathway

AIM

To investigate the apoptotic effects of melittin on SGC-7901 cells via activation of the mitochondrial signaling pathway in vitro.

METHODS

SGC-7901 cells were stimulated by melittin, and its effect on proliferation and apoptosis of was investigated by methyl thiazolyl tetrazolium assay, morphologic structure with transmission electron microscopy, annexin-V/propidium iodide double-staining assay, measuring mitochondrial membrane potential (MMP) levels, and analyzing reactive oxygen species (ROS) concentrations were analyzed by flow cytometry. Cytochrome C (Cyt C), apoptosis-inducing factor (AIF), endonuclease G (Endo G), second mitochondria-derived activator of caspases (Smac)/direct IAP binding protein with low isoelectric point (Diablo), and FAS were analyzed by western blot. The expression of caspase-3 and caspase-8 was measured using activity assay kits.

RESULTS

Melittin was incubated at 1.0, 2.0, 4.0, or 6.0 μg/mL for 1, 2, 4, 6, or 8 h and showed a time- and concentration-dependent inhibition of SGC-7901 cell growth. Melittin induced SGC-7901 cell apoptosis, which was confirmed by typical morphological changes. Treatment with 4 μg/mL melittin induced early apoptosis of SGC-7901 cells, and the early apoptosis rates were 39.97% ± 3.19%, 59.27% ± 3.94%, and 71.50% ± 2.87% vs 32.63% ± 2.75% for 1, 2, and 4 h vs 0 h (n = 3, P < 0.05); the ROS levels were 616.53% ± 79.78%, 974.81% ± 102.40%, and 1330.94% ± 93.09% vs 603.74% ± 71.99% (n = 3, P < 0.05); the MMP values were 2.07 ± 0.05, 1.78 ± 0.29, and 1.16 ± 0.25 vs 2.55 ± 0.42 (n = 3, P < 0.05); caspase-3 activity was significantly higher compared to the control (5492.3 ± 321.1, 6562.0 ± 381.3, and 8695.7 ± 449.1 vs 2330.0 ± 121.9), but the caspase activity of the non-tumor cell line L-O2 was not different from that of the control. With the addition of the caspase-3 inhibitor (Ac-DEVD-CHO), caspase-3 activity was significantly decreased compared to the control group (1067.0 ± 132.5 U/g vs 8695.7 ± 449.1 U/g). The expression of the Cyt C, Endo G, and AIF proteins in SGC-7901 cells was significantly higher than those in the control (P < 0.05), while the expression of the Smac/Diablo protein was significantly lower than the control group after melittin exposure (P < 0.01). Ac-DEVD-CHO did not, however, have any effect on the expression of caspase-8 and FAS in the SGC-7901 cells.

CONCLUSION

Melittin can induce apoptosis of human gastric cancer (GC) cells through the mitochondria pathways, and it may be a potent agent in the treatment of human GC.

Novel findings about management of gastric cancer: A summary from 10th IGCC

The Tenth International Gastric Cancer Congress (IGCC) was held in Verona, Italy, from June 19 to 22, 2013. The meeting enclosed various aspects of stomach tumor management, including both tightly clinical approaches, and topics more related to basic research. Moreover, an overview on gastrointestinal stromal tumors was provided too, although here not discussed. Here we will discuss some topics related to molecular biology of gastric cancer (GC), inherent to prognostic, diagnostic and therapeutic tools shown at the conference. Results about well known subjects, such as E-cadherin loss of expression/function, were presented. They revealed that other mutations of the gene were identified, showing a continuous research to improve diagnosis and prognosis of stomach tumor. Simultaneously, new possible molecular markers with an established role for other neoplasms, were discussed, such as mesothelin, stomatin-like protein 2 and Notch-1. Hence, a wide overview including both old and new diagnostic/prognostic tools was offered. Great attention was also dedicated to possible drugs to be used against GC. They included monoclonal antibodies, such as MS57-2.1, drugs used in other pathologies, such as maraviroc, and natural extracts from plants such as biflorin. We would like to contribute to summarize the most impressive studies presented at the IGCC, concerning novel findings about molecular biology of gastric cancer. Although further investigations will be necessary, it can be inferred that more and more tools were developed, so as to better face stomach neoplasms.

Critical role of spatial interaction between CD8⁺ and Foxp3⁺ cells in human gastric cancer: the distance matters

PURPOSE

In various cancer types, an abundance of FoxP3(+) regulatory T cells (Treg) has been associated with an unfavorable outcome. Yet, the role of Treg on cancer immunity has been shown to be complex. In single cell marker technique, other tumor-infiltrating lymphocytes (TILs) such as cytotoxic CD8(+) T cells (CTL) also influenced prognosis. This study for the first time investigates the concurrent spatial distribution pattern of CD8(+) and FoxP3(+) TILs and their prognostic impact in human gastric cancer.

MATERIALS AND METHODS

Tumor tissue microarrays of 50 patients with surgically treated adenocarcinoma of the cardia were studied. An immunohistochemical double staining of CD8(+) and FoxP3(+) TILs was performed. Cell counts and cell-to-cell distances in tumor epithelium and stroma were evaluated with image-processing software. Metastasis-free survival, no-evidence-of-disease survival, and overall survival were investigated (mean follow-up time 6.9 years).

RESULTS

High intraepithelial infiltration of CD8(+) and FoxP3(+) TIL was associated with the improved 10-year metastasis-free survival (83 vs. 54%, p = 0.04 and 85 vs. 59%, p = 0.09, respectively). Considering cell-to-cell distance and comparing patients with functional (30-110 μm) versus nonfunctional distances of CD8(+) and FoxP3(+) TILs, 10-year survival rates differed between 89 and 55% (p = 0.009), respectively.

CONCLUSION

Prognostic influence of tumor-infiltrating immune cells in gastric cancer critically depends on their cell-to-cell distance. FoxP3(+) TILs must be located within a distance between 30 and 110 μm of CD8(+) T cells to positively impact on prognosis.

siRNA-participated chemotherapy: an efficient and specific therapeutic against gastric cancer

PURPOSE

This study aims to investigate the role of siRNA silencing fibroblast growth factor receptor (FGFR) expression in promoting chemotherapy effect of gastric cancer and to explore its mechanism.

METHODS

Human gastric cancer cells MGC80-3 were divided into four groups: control group, cisplatin group (2 μg/L), cisplatin (2 μg/L) + siRNA group and siRNA group. The expressions of FGFR in four groups were detected by immunofluorescence. The cell proliferation and apoptosis were detected by MTT assay and flow cytometry. The protein expression levels of vascular endothelial growth factor receptor (VEGFR), caspase-3 and Bax were detected by Western blot. Further, animal model of gastric cancer was established and divided into four groups as in vitro experiment. The expression of FGFR mRNA in tumor tissue was detected by the real-time fluorescence quantitative polymerase chain reaction. The size of tumor was measured to analyze the effects of treatment. Histopathological detections were performed by hematoxylin and eosin staining and immunohistochemistry.

RESULTS

For in vitro experiment, significant decrease inFGFR expression, inhibition of proliferation and promotion of apoptosis were observed in siRNA-treated cells, so as cisplatin group. siRNA also resulted in the reduction of VEGFR and rise in apoptosis-related protein (caspase-3). As for the experiment in vivo, siRNA also suppressed the expression of FGFR and enhanced tumor shrink. Furthermore, the co-administration of siRNA and cisplatin revealed a more excellent antitumor effect than other therapies.

CONCLUSIONS

siRNA can effectively suppress FGFR expression and cell proliferation, but promote apoptosis in vitro and also inhibit tumor growth and FGFR production in vivo. siRNA-participated chemotherapy may provide an efficient therapeutic approach to treat gastric cancer.

Rare case of Helicobacter pylori-related gastric ulcer: Malignancy or pseudomorphism?

Helicobacter pylori (H. pylori) is a pathogen and the most frequent cause of gastric ulcers. There is also a close correlation between the prevalence of H. pylori infection and the incidence of gastric cancer. We present the case of a 38-year-old woman referred by her primary care physician for screening positron emission tomography-computed tomography (PET-CT), which showed a nodular strong accumulation point with standardized uptake value 5.6 in the gastric fundus. Gastroscopy was then performed, and a single arched ulcer, 12 mm in size, was found in the gastric fundus. Histopathological examination of the lesion revealed chronic mucosal inflammation with acute inflammation and H. pylori infection. There was an obvious mitotic phase with widespread lymphoma. Formal anti-H. pylori treatment was carried out. One month later, a gastroscopy showed a single arched ulcer, measuring 10 mm in size in the gastric fundus. Histopathological examination revealed chronic mucosal inflammation with acute inflammation and a very small amount of H. pylori infection. The mitotic phase was 4/10 high power field, with some heterotypes and an obvious nucleolus. Follow-up gastroscopy 2 mo later showed the gastric ulcer in stage S2. The mucosal swelling had markedly improved. The patient remained asymptomatic, and a follow-up PET-CT was performed 6 mo later. The nodular strong accumulation point had disappeared. Follow-up gastroscopy showed no evidence of malignant cancer. H. pylori-associated severe inflammation can lead to neoplastic changes in histiocytes. This underscores the importance of eradicating H. pylori, especially in those with mucosal lesions, and ensuring proper follow-up to prevent or even reverse early gastric cancer.