miRNAs as Biomarker of Gastric Cancer: Emphasis on Plasma miRNAs

Gastric cancer is the fifth common malignancy after lung, breast, colorectal and prostatecancers, also after the cancers of lung and liver it is the third cancer causing death in theworld. Because of poor techniques of early diagnosis, gastric cancer is commonly diagnosedat advanced stage in which most of the patients are near to death (poor prognosis with 5-yearsurvivals below 24%). As we know the best chance of treatment is in the earlier stages, weneed to find some biomarkers that help us to enhance early diagnosis rate. miRNAs aresmall non-coding RNA molecules (17~22 nt) which function in the regulation of cell growth,differentiation, and apoptosis. Dysregulation of miRNAs has been seen in different types ofcancers. Many studies proved that altered expressions of miRNAs are tightly associated withtumori genesis, progression, angiogenesis and prognosis of gastric cancer. Even some ofthese altered miRNAs show correlations with size, stage and lymph nodes or distantmetastasis of gastric tumor. Molecular targeting of certain miRNAs has anticancer andtherapeutic effects in gastric cancer and even can block metastasis. We can obtain miRNAsnot only from frozen or paraffin-embedded tissues and cell-lines, but also from patient’swhole blood. Circulating miRNAs (miRNAs available in plasma) have high stability afterprolonged incubation at room temperature and/or multiple freezing†thawing processes.Recent studies report that miRNAs detectable in plasma can be used as new biomarkers in awide range of cancers, among of them is gastric cancer. Considering being available inserum and plasma, miRNAs can be used as biomarkers for non invasive diagnosis andtreatment of gastric cancer. Plasma miRNAs assays have potential for clinical use, includingscreening of people with high risk of cancer.

Keywords:

Gastric Cancer , miRNA , Biomarker , Plasma , Serum