en Cancer Biology Cancer Biology مقاله کامل Full Length/Original Article <strong>Background:</strong> Gastric cancer (GC) is one of the most prevalent cancers with a high rate of mortality in the world. In recent years, microRNAs (miRNAs) have been proposed to be involved in GC development. In this study, we aimed at investigating differential expression level of miR-155-5p, miR-15a, miR-15b, and miR-186 in GC. <strong>Methods:</strong> For this research, we used qPCR to investigate miR-15b, miR-155, miR-15a, and miR-186 expression levels in a total of 29 normal gastric tissue, 45 gastric dysplasia, and 39 GC samples. <strong>Results: </strong>We showed significant down-regulation of miR-155-5p (<em>p</em> = 0.0018), miR-15a (<em>p</em> = 0.0159), and miR-186 (<em>p </em>= 0.0005) expression in GC tissue. <strong>Conclusion:</strong> This study provides evidence for deregulated expression of miR155-5p, miR-186, and miR-15a in GC and is providing new insights into the potential implication of these miRNAs in the pathogenesis of GC.&nbsp; Dysplasia, Gastric cancer, MicroRNAs, MicroRNA stomach cancer 338 343 http://ibj.pasteur.ac.ir/browse.php?a_code=A-10-1-765&slc_lang=en&sid=1 Ali Zare 0000-0001-5922-3143 No Department of Medical Genetics, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran; Behnam Alipoor 0000-0001-7384-4034 No Department of Laboratory Sciences, Faculty of Paramedicine, Yasuj University of Medical Sciences, Yasuj, Iran; Mir Davood Omrani 0000-0002-0673-9717 Yes Department of Medical Genetics, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran; Mohammad Reza Zali 0000-0002-9027-4560 No Gastroenterology and Liver Diseases Research Center, Research Institute for Gastroenterology and Liver Diseases, Shahid Beheshti University of Medical Sciences, Tehran, Iran; Nasser Malekpour Alamdari 0000-0003-3278-9205 No Department of General Surgery, Clinical Research and Development Unit at Modarres Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran Hamid Ghaedi 0000-0002-5034-0586 No Department of Medical Genetics, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran;