Aberrant expression of miR-203 and its clinical significance in gastric and colorectal cancers.

<bold>Background: </bold>MicroRNAs (miRNAs) are small, non-coding RNAs of endogenous origin, they have been increasingly shown to have aberrant expression in many tumor types. miR-203 has not been comprehensively investigated in gastric and colorectal cancers.<bold>Methods: </bold>Total RNA was extracted from tissues of 212 patients with gastric or colorectal cancer as well as from seven gastric and colorectal cell lines. We determined the expression of miR-203 by real-time PCR and calculated using the 2-ΔΔCt method. Then, we assessed miR-203 expression and clinicopathologic characteristics. Finally, we studied the effect of miR-203 on cell proliferation in SGC-7901 cells by MTT.<bold>Results: </bold>miR-203 has significantly low expression in colorectal cancer tissues (p < 0.001, paired t test) and cancer cell lines compared to non-tumor counterparts. Moreover, low expression of miR-203 was correlated with tumor size (p = 0.015, non-parametric test) and pT stage (p = 0.005) in colorectal cancer. Although expression of miR-203 was not significant in gastric cancer tissues (p = 0.124), interestingly, miR-203 was correlated with tumor size (p = 0.023), macroscopic type (p = 0.045), and pT stage (p = 0.013). Furthermore, we found miR-203 can inhibit the cell proliferation in SGC-7901 cells.<bold>Conclusion: </bold>miR-203 may be related to the proliferation and invasion of gastric and colorectal cancers. [ABSTRACT FROM AUTHOR]