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Oncol Rep. 2011 Nov;26(5):1329-35. doi: 10.3892/or.2011.1401. Epub 2011 Jul 22.

Epigenetic silencing of microRNA-373 plays an important role in regulating cell proliferation in colon cancer.

Author information

1
Department of Medicine and Clinical Oncology, Graduate School of Medicine, Chiba University, Chiba 260-8670, Japan.

Abstract

microRNAs (miRNA) are non-coding RNAs that negatively control gene expression by cleaving or inhibiting the translation of target gene mRNAs. We used a microarray-based transcriptomic analysis to identify miRNA expression levels that changed in response to epigenetic factors. Specifically, we searched for increased expression of miRNAs prepared from colon cancer cell line DLD-1 after a 96-h treatment with 5 ┬ÁM of 5-aza-2'-deoxycytidine (DAC). Among those identified, transient transfection of miRNA hsa-miR-373 resulted in cytostasis. In addition, bisulfate sequence analysis of the promoter regions of these miRNAs showed aberrant methylation in the cancer cells. In clinical colon samples, hsa-miR-373 was down-regulated in colon cancers (29/40, 72.5%) relative to control samples, whereas the purported oncogene RAB22A (a target gene of hsa-miR-373) was up-regulated (24/40, 60%). Using methylation-specific PCR, we also observed aberrant methylation of hsa-miR-373 in colon cancers (35/40, 87.5%) relative to controls (8/40, 20%). Based on these results, we conclude that expression of hsa-miR-373 is down-regulated by aberrant methylation in colon cancer and that this miRNA may function by regulating expression of the oncogene RAB22A.

PMID:
21785829
DOI:
10.3892/or.2011.1401
[Indexed for MEDLINE]

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