Bacterial and tissue biomarkers of gastric cancer: new findings and future perspectives

Gastric cancer (GC) is the second leading cause of cancer-related deaths worldwide. It has been proposed that the specific genotypes of Helicobacter pylori (H. pylori) are the causative agents in the development of gastroduodenal diseases, such as chronic atrophic gastritis, peptic ulcerations, and GC. However, disease progression to GC occurs in only a small proportion of infected patients. Recently, we identified a novel polymorphic site in the 3ʹ-end region of H. pylori vacA gene. The vacA c1 genotype increased the risk of GC. This association was independent of and larger than the associations of the m-, i-, and d-type of vacA or cagA status with GC. Therefore, treatment of H. pylori infection may be an effective way to prevent GC. Expression of cytokines and their associations with inflammatory responses has been shown. Several cytokine polymorphisms, such as IL-1B, IL-8, IL-10, and TNF-α have been considered as risk factors for GC. It has been shown that the interaction of bacterial genotypes and host factors plays an essential role in developing GC. Several altered molecular pathways are involved in the pathogenesis of GC. Micro-RNAs are small, non-coding RNAs of 18-25 nucleotides in length that regulate the expression of target mRNAs. Expression pattern of cancer cells is different compared with the normal cells. Micro-RNAs plays a critical role in apoptosis and classified in two groups: pro- and anti-apoptotic agents. Recent studies have confirmed the oncogenic or tumor suppression role of micro-RNAs in cancer cells. They play a significant role in the GC cell physiology and tumor progression, by translational suppression of target genes. These small RNAs have therefore emerged as a new type of GC biomarker with immeasurable clinical potential. Generally, a variety of micro-RNAs involved in different stages of cancer, including tumorigenesis, angiogenesis, and metastasis. Considering to this issue more than 50% of cancers can be cured, if they were diagnosed in the early stages. Hence, identifying the biomarkers of GC could play an important role in prevention, early diagnosis and rapid treatment of patients. In this review article, we have reviewed the latest findings about bacterial and tissue biomarkers of GC