Abstract
Meta-analyses have shown that microRNA polymorphisms have variable effects in different population. Yet, no meta-analysis investigated the association of two common polymorphisms of miRNA, mir-499 rs3746444 polymorphism and mir-149 rs2292832 polymorphism, with cancer risk in the Chinese population. We searched the PubMed, Web of Knowledge, MEDLINE, CNKI databases, as well as Cochrane library, updated on December 31, 2012 for assays regarding cancer risk association with these two common polymorphisms in the present meta-analysis. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were used to explore the strength of associations. The results showed that rs3746444 polymorphism was associated with increased cancer risk (dominant model: GG/AG vs. AA: OR = 1.43, 95% CI: 1.14-1.80; recessive model: GG vs. OR = 1.54, 95% CI: 1.04-2.30; homozygote model: GG vs. AA: OR = 1.69, 95% CI: 1.10-2.60; heterozygote model: AG vs. AA: OR = 1. 35, 95% CI: 1.09-1.67), and rs3746444 was associated with liver cancer in the subgroup of cancer types. For the rs2292832 polymorphism, the results showed no significant risk association in both overall pooled analysis and subgroup of cancer types, smoking status, gender and tea drinking status in the Chinese population. This meta-analysis suggested that the rs3746444 GG genotype is associated with increased cancer risk, especially liver cancer, while the rs2292832 polymorphism showed no association with cancer risk in Chinese.
Highlights
MicroRNAs, encoded by eukaryotic nuclear DNA, is a small nonprotein-coding single-stranded RNA molecules of 18 to 24 nucleotides in length, with gene regulatory functions
When stratified by cancer type, rs3746444 polymorphism was associated with liver cancer (GG vs. AG/AA: Odds ratios (ORs) = 1.93, 95% confidence intervals (95% CIs): 1.04-3.58; GG vs. AA: OR = 2.17, 95% CI: 1.15-4.10), while rs3746444 polymorphism was not associated with lung cancer
The gene frequency of TT and TC/CC in different smoking status and gender can be extract in one publication (Zhang et al, 2011), and the gene frequency of TT, TC and CC in different smoking status, tea drinking status and gender can be extract in one publication (Zhang et al, 2012).When stratified by these factors, no significant association was observed between these models and cancer risk (Table 2)
Summary
MicroRNAs (miRNA), encoded by eukaryotic nuclear DNA, is a small nonprotein-coding single-stranded RNA molecules of 18 to 24 nucleotides in length, with gene regulatory functions. Each miRNA has hundreds or thousands of target genes, almost all the coding genome is under the control of miRNAs (Fabbri et al, 2013). Mature miRNAs, stably associated with RISC (RNA-induced silencing complex), regulate target messenger RNAs (mRNAs) (Bartel, 2004), causing a suppression in gene expression levels (Filipowicz et al, 2008), while others can promote gene expression (Vasudevan et al, 2007). In this way, some miRNAs perform mainly as tumor suppressor genes, while others function as oncogene
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