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Background and purpose: Gastric carcinoma is the second leading cause of cancer death worldwide and its incidence varies considerably according to geographical location. There are multiple etiologic factors such as infection with ËBV that play a role in carcinogenesis of gastric cancer, yet there is not enough evidence about pathogenesis of ËBV and its relationship with gastric cancer. Thus, recognizing pathogenic genes can help improve the prognosis of the patients. The purpose of this study is to explore the relationship between ËBV and ËBV-encoded BÂRF-1 oncogene in gastric adenocarcinoma pathogenesis.
Materials and methods: Ïn this analytical case-control study, 200 paraffin-embedded blocks of biopsies of patients with gastric cancer and those of healthy people were selected. Âfter DNÂ extraction, polymerase chain reaction (PÇR) was used to determine ËBV genome and BÂRF-1 oncogene by specific primers of BÂRF-1. Grade and stage of the gastric cancer biopsies were also examined.
Results: The results of PÇR indicated that ËBV genome was detected in three cases in the case group, whereas all samples in the control group were negative for ËBV. Thus, no significant relationship was observed between the two groups (P>0.05). The ËBV positive gastric cancers were negative for BÂRF-1 oncogene. Ït was also found that 41% of the cancers were grade Ï, 52% grade ÏÏ, and 7% grade ÏÏÏ.
Çonclusion: The findings suggest that gastric cancer has a high prevalence in the geographical region under study however, ËBV plays a minor role in the carcinogenesis of gastric adenocarcinoma.

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Background and purpose: Melatonin is a neurohormone with important physiologic and pharmacologic role in human body especially in circadian rhythm .In recent years, some progress has been achieved to show its role in regulating in prevention of cancer especially breast and colon cancer. According to this background and as there was not any precise cellular research about the role of melatonin in gastric cancer in which this study this study has been aimed. Materials and methods: In this study, we used MTT assay procedure. Also, we have provided AGS and MKN-45 cell line from national cell bank, Institute Pasteur of Iran. The cells were cultured in RPMI medium in 5% CO2, 370C in 96 wells culture plate and then were incubated with melatonin and cisplatin (as positive control) for 48 hr. in 5 different concentrations. The proliferation index as cell viability was achieved and compared with controls groups with ELISA concerning Formazan crystal color absorbance between 450-690 nm. Results: Our results showed that melatonin in 12.5-200 µM has significant anti-proliferative effects in AGS cells and in 50-200 µM in MKN-45 compared with control and these results were in parallel with the effects of cisplatin. Conclusion: According to our data, we have shown that melatonin in a dose -dependent manner has antiproliferative effect in gastric adenocarcinoma cells and this effect in AGS cells was more potent than MKN-45 but more studies are needed to find the kind of receptors and the interacellular signaling pathways.

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Background and purpose: According to recent studies melatonin has been known as a potent anti-oxidant with anti-oncostatic and cytoprotective properties. The gastrointestinal tract is the major source of melatonin in periphery. Therefore, many scientists suppose a protective role for melatonin in gastrointestinal tract. Also, there is a high rate of gastric adenocarcinoma in Mazandaran province of Iran, so this study investigated the expression of melatonin receptor in gastrointestinal patients with focusing on MT2 as an important melatonin receptor which its role in many cancers has been shown peviously. Materials and methods: Gastric adenocarcinoma patients from Mazandaran province of Iran were selected for this study and normal individuals as control. After extracting RNA from 30 gastric cancer tissues and 30 normal tissues and preparing cDNA, the expression of melatonin receptor (type 2) has been assayed with Real-time PCR. Results: Our experiment has been shown for the first time in Mazandarn province, high expression of melatonin receptor type 2 in gastric cancer tissues compared to control.Also it was revealed that this expression in marginal of cancer patients was more than cancer tissues and negative control. Conclusion: In this study for the first time we found the expression of melatonin receptor in gastric adenocarcinoma tissues which was in consistent with other studies as breast and colon cancer and a high expression in marginal tissues indicates a refractory mechanism and defending role of melatonin in GI system .Also high experession of this receptor in gastric cancer people of Mazandarn province may help to know better the etiology of high incidence of this kind of cancer in this area.