Suicide journey of H. pylori through gastric carcinogenesis: the role of non-H. pylori microbiome and potential consequences for clinical practice.

Despite being one of the most studied cancer-related infections, the relationship between Helicobacter pylori infection and gastric adenocarcinoma (GC) remains, in some points, obscure. Based on a critical analysis of the available literature regarding stomach microbiota, we aimed to shed light to a possible new interpretation of the current understanding about the Helicobacter pylori-related GC carcinogenesis. We analyzed data from the literature on Helicobacter pylori and other potential carcinogenic pathogens, in both benignant conditions and gastric adenocarcinoma. Helicobacter pylori is the dominant microorganism in benignant conditions as non-complicated gastritis. In atrophic gastritis, metaplasia and, mainly, in gastric adenocarcinoma, a strong reduction in Helicobacter pylori abundance, and increased occurrence of other microorganisms is strongly demonstrated by metagenomic experiments. While causing peptic disease and keeping the stomach's high acidity, Helicobacter pylori infection avoids gastric infection by carcinogenic intestinal microbiota. Nevertheless, Helicobacter pylori persistence may also provoke an atrophic gastritis, a condition that causes its own decline, due to a microenvironment modification, including reduced acidity, resulting in Helicobacter pylori substitution by a cancer-prone microbiota. This new interpretation might result in a dramatic modification on clinical management of Helicobacter pylori-related gastric disease.

In vitro assessment of cytotoxic, genotoxic and mutagenic effects of antimalarial drugs artemisinin and artemether in human lymphocytes.

Artemisinin is a substance extracted from the Chinese plant Artemisia annua L. widely used in natural medicine for the treatment of various diseases. Artemether is a substance synthesized from artemisinin, and both drugs are commonly administered in the treatment of malaria. Although considered effective antimalarial drugs, very little is known about the genotoxic, cytotoxic and mutagenic effects of these drugs. Therefore, in the present study, we evaluated the genotoxic, mutagenic and cytotoxic effects of artemisinin (12.5, 25 and 50 µg/mL) and artemether (7.46; 14.92 and 29.84 µg/mL) in cultured human lymphocytes using the comet assay, the micronucleus test and the cytotoxicity assay for detection of necrosis and apoptosis by acridine orange/ethidium bromide staining. Our results showed a significant increase (p < 0.05) in the rate of DNA damage measured by comet assay and in the micronucleus frequency after treatment with both drugs. It was also observed that only artemisinin induced a statistically significant increase (p < 0.05) in the number of lymphocytes with death by necrosis 48 h after treatment. The results demonstrated that these two drugs induce mutagenic, genotoxic and cytotoxic effects in cultured human lymphocytes. Our data indicate the need for caution in the use of such drugs, since genotoxic/mutagenic effects may increase the risk of carcinogenesis.

In vitro evaluation of the cytotoxic and genotoxic effects of artemether, an antimalarial drug, in a gastric cancer cell line (PG100).

Artemisinin is a sesquiterpene lactone endoperoxide, obtained from Artemisia annua, and extensively used as an antimalarial drug. Many studies have reported the genotoxic and cytotoxic effects of artemisinins; however, there are no studies that compare such effects between cancer cell lines and normal human cells after treatment with artemether, an artemisinin derivative. Gastric cancer is the fourth most frequent type of cancer and the second highest cause of cancer mortality worldwide. Thus, the aim of this study was to evaluate the in vitro genotoxic and cytotoxic effects induced by artemether in gastric cancer cell line (PG100) and compare them with the results obtained in human lymphocytes exposed to the same conditions. We used MTT (3-(4,5-methylthiazol-2-yl)-2, 5-diphenyl-tetrazolium bromide) assay, comet assay and ethidium bromide/acridine orange viability staining to evaluate the cytotoxic and genotoxic effects of artemether in PG100. MTT assay showed a decrease in the survival percentages for both cell types treated with different concentrations of artemether (P < 0.05). PG100 also showed a significant dose-dependent increase in DNA damage index at concentrations of 119.4 and 238.8 µg ml(-1) (P < 0.05). Our results showed that artemether induced necrosis in PG100 at concentrations of 238.8 and 477.6 µg ml(-1), for all the tested harvest times (P < 0.05). In lymphocytes, artemether induced both apoptosis and necrosis at concentrations of 238.8 and 477.6 µg ml(-1), for all the tested harvest times (P < 0.05). In conclusion, human lymphocytes were more sensitive to the cytotoxic effects of the antimalarial drug than the gastric cancer cell line PG100.

Identification of IL11RA and MELK amplification in gastric cancer by comprehensive genomic profiling of gastric cancer cell lines.

AIM: To identify common copy number alterations on gastric cancer cell lines. METHODS: Four gastric cancer cell lines (ACP02, ACP03, AGP01 and PG100) underwent chromosomal comparative genome hybridization and array comparative genome hybridization. We also confirmed the results by fluorescence in situ hybridization analysis using the bacterial artificial chromosome clone and quantitative real time PCR analysis. RESULTS: The amplification of 9p13.3 was detected in all cell lines by both methodologies. An increase in the copy number of 9p13.3 was also confirmed by fluorescence in situ hybridization analysis. Moreover, the interleukin 11 receptor alpha (IL11RA) and maternal embryonic leucine zipper kinase (MELK) genes, which are present in the 9p13.3 amplicon, revealed gains of the MELK gene in all the cell lines studied. Additionally, a gain in the copy number of IL11RA and MELK was observed in 19.1% (13/68) and 55.9% (38/68) of primary gastric adenocarcinoma samples, respectively. CONCLUSION: The characterization of a small gain region at 9p13.3 in gastric cancer cell lines and primary gastric adenocarcinoma samples has revealed MELK as a candidate target gene that is possibly related to the development of gastric cancer.

The role of piRNA and its potential clinical implications in cancer.

Epigenetic mechanisms work in an orchestrated fashion to control gene expression in both homeostasis and diseases. Among small noncoding RNAs, piRNAs seem to meet the necessary requirements to be included in this epigenetic network due to their role in both transcriptional and post-transcriptional regulation. piRNAs and PIWI proteins might play important roles in cancer occurrence, prognosis and treatment as reported previously. Nevertheless, the potential clinical relevance of these molecules has yet been elucidated. A brief overview of piRNA biogenesis and their potential roles as part of an epigenetic network that is possibly involved in cancer is provided. Moreover, potential strategies based on the use of piRNAs and PIWI proteins as diagnostic and prognostic biomarkers as well as for cancer therapeutics are discussed.

Effects on DNA repair in human lymphocytes exposed to the food dye tartrazine yellow.

Tartrazine is a food additive that belongs to a class of artificial dyes and contains an azo group. Studies about its genotoxic, cytotoxic and mutagenic effects are controversial and, in some cases, unsatisfactory. This work evaluated the potential in vitro cytotoxicity, genotoxicity and effects on DNA repair of human lymphocytes exposed to the dye. We assessed the cytotoxicity of tartrazine by 3-(4,5-Dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide test and the response of DNA repair through comet assay (alkaline version). We used different concentrations of the dye, ranging from 0.25-64.0 mM. The results demonstrated that tartrazine has no cytotoxic effects. However, this dye had a significant genotoxic effect at all concentrations tested. Although most of the damage was amenable to repair, some damage remained higher than positive control after 24 h of repair. These data demonstrate that tartrazine may be harmful to health and its prolonged use could trigger carcinogenesis.

High-density array comparative genomic hybridization detects novel copy number alterations in gastric adenocarcinoma.

AIM: To investigate frequent quantitative alterations of intestinal-type gastric adenocarcinoma. MATERIALS AND METHODS: We analyzed genome-wide DNA copy numbers of 22 samples and using CytoScan® HD Array. RESULTS: We identified 22 gene alterations that to the best of our knowledge have not been described for gastric cancer, including of v-erb-b2 avian erythroblastic leukemia viral oncogene homolog 4 (ERBB4), SRY (sex determining region Y)-box 6 (SOX6), regulator of telomere elongation helicase 1 (RTEL1) and UDP-Gal:betaGlcNAc beta 1,4- galactosyltransferase, polypeptide 5 (B4GALT5). The most significant alterations related to peritoneal invasion involved the regions 13q21.1 (gain) and 15q15.1, 17q23.1, 19q13.2 and 20q11.22 (loss of heterozygozity; LOH), where we found LOH of erythrocyte membrane protein band 4.1-like 1 (EPB41L1) gene. In relation to early age of onset, the most significant alterations were gains in the regions Xq26 and Xp22.31 and a loss in the region 11p15.4. CONCLUSION: These quantitative changes may play a role in the development of this type of neoplasia and may be used as markers in evaluating poor prognosis, as well as act as potential therapeutic targets for gastric cancer.