Evaluation of miR-21 and miRNA-221 in gastric tumor and their correlation with RECK and CDKN1B expression

Recent studies on expression patterns of miR-21 and miR- 221 genes in gastric cancer suggest their key role in tumorigenesis. However, their molecular mechanism in cancer and especially gastric cancer has not been well understood. In this study, we aimed to investigate the association of these two micro RNAs expression and their target genes in normal and gastric carcinoma tissues.

Thirty two gastric cancer tissues and its adjacent non-tumorous tissues were collected from patients referred to the cancer institute of Imam Khomeini hospital during 2008-2011. Total RNA was isolated and then cDNAs for microRNAs and mRNA were synthesized. The expression levels of miR-21 and miR-221 were detected by quantitative Real time RT- PCR using a 5s rRNA and 18s rRNA as the internal reference genes.

miR-21 and miR-221 expression were significantly up-regulated in cancerous samples compared to its adjacent non-tumorous tissue. The mean expression of miR-21 in the tumor sample was 4.18± 1.07 (P <0.001) and the mean expression of miR-221 was 5.75± 2.07 (P <0.001). The expression levels of miR-21 and miR-221 were negatively correlated with the expression levels of RECK and CDKN1B/p27 respectively.

This study showed the expression of miR-21 and miR-221 increased in gastric cancer. There was a significant inverse correlation between increased expression of miR-21 and decreased expression of RECK, as well as between increased expression of miR-221 and decreased expression of CDKN1B. As a result, mi R-21 and miR-221 can be suggested two biomarkers in gastric cancer.