Elevated expression of mature miR-21 and miR-155 in cancerous gastric tissues from Chinese patients with gastric cancer

Li Liu,Qi Chen,Rensheng Lai,Xiaobin Wu,Xiaoyu Wu,Fukun Liu,Guohua Xu,Yong Ji

doi:10.1016/s1674-8301(10)60028-0

Abstract

Objective MicroRNA (miRNA) expression is deregulated in many types of human cancers. We sought to investigate the expression patterns of the miRNAs, miR-21, miR-145 and miR-155 in sporadic gastric cancer in a Chinese population. Methods Total RNA was extracted from archived gastric cancer tissues and adjacent non-cancerous tissues from 20 pairs of paraffin-embedded specimens. Expression levels of miR-21, miR-145 and miR-155 were detected by quantitative reverse transcriptase PCR using a specific stem-loop primer, with U6 as the internal reference gene. Results The expression of miR-21 and miR-155 in gastric cancer samples was significantly higher than in paired non-cancerous samples ( P < 0.05). There was no statistically significant difference in expression levels of miR-145 between cancerous and non-cancerous tissues ( P > 0.05). Conclusion In Chinese sporadic gastric cancer tissues, the expressions of the oncogenic miR-21 and miR-155 were significantly up-regulated, while the expression of the tumor suppressor miR-145 was decreased, although this decrease was not statistically significant. Thus there is specificity in the miRNA expression pattern in gastric cancers in the Chinese population.

Highlights

MicroRNAs are small, non-coding RNAs of 19-24 nucleotides in length that were first reported by Lee and colleagues[1]
The relationship between alteration in the expression of miRNAs and gastric cancer is a challenging issue for researchers
Zhang et al[29] found that the expression level of let-7a miRNA in gastric tumor tissues was significantly reduced when compared to normal tissues in 14 samples from 32 patients. miRNA expression profiling revealed a limited set of miRNAs with altered expression in the multidrugresistant (MDR) gastric cancer cell line SGC7901/ VCR compared to its parental SGC7901 cell line[30]

Summary

Introduction

MicroRNAs (miRNAs) are small, non-coding RNAs of 19-24 nucleotides in length that were first reported by Lee and colleagues[1]. Sequences of miRNAs are highly conserved[2], and they regulate gene expression at a post-transcriptional level, most commonly by inhibiting mRNA translation or promoting mRNA degradation[3]. MiRNAs are frequently misregulated in human malignancies[4]. Over the past 10 years, many findings have strongly supported a role for miRNAs in the regulation of crucial processes such as cell proliferation[5], apoptosis[6], development[7], differentiation[8] and metabolism[9]. MiRNAs dysfunction may contribute to a variety of human diseases such as cancer, cardiovascular disease, liver disease, immune dysfunction and metabolic disorders[10]. The first evidence that miRNAs were involved in cancer came from the finding that miR-15a and miR-16-1 were down-regulated or deleted in most patients with. MiRNAs may act as oncogenes or tumor suppressor genes, and sometimes both[12,13]

Methods

Results

Conclusion