Increased Expression of MicroRNA-210 in Microsatellite Instability High Endometrial Carcinoma and Its Potential Role in DNA Damage Repair.
Deqin Ma, Zhao Chen, Hanyin Cheng, Bojana Djordjevic, Keyur P Patel, Madan G Luthra, Bedia A Barkoh, Su-Su Xie, Shuguang Ma, Gang Chen, Jeffrey Medeiros, Russell Broaddus, Rajyalakshmi Luthra. The University of Texas M. D. Anderson Cancer Center Center, Houston
Background: Endometrial carcinoma (EC) is the most common malignant neoplasm of the female reproductive tract. Young women (< 40 years) with EC usually have a better prognosis and are managed conservatively. Approximately 20% of ECs are associated with microsatellite instability (MSI-high). MicoRNAs (miR) are small non-coding RNAs that regulate gene expression. Differential expression of miRs has been shown in MSI colorectal carcinomas. In this study, we report for the first time the miR expression profile in MSI-high and microsatellite stable (MSS) ECs.
Design: RNA was extracted from frozen endometrial tumors (15 MSI and 15 MSS) using the RNeasy Mini kit (Qiagen, Valenica, CA). 100 ng RNA was labeled with Cyanine 3-pCp and hybridized onto the Agilent Human miRNA V3 8X15K microarray (Agilent Technologies). The slides were scanned using a G2565BA scanner (Agilent). The data were extracted using Agilent Feature Extraction Software and analyzed by Nexus Expression Revision 2.0 (Biodiscovery). MiRs identified by microarray were validated by quantitative real time PCR. The potential targets of miR were identified by in-silico prediction algorithms using the Sanger miRBase (http://www.mirbase.org).
Results: A total of 11 miRs (miR-26a, -30a, -30e, -34a, 92a, -130a, -210, -1246, -1290, let7b and let7c) were differentially expressed in MSI-high tumors by microarray. Six of these miRNAs (let-7b, miR-210, -26a, -30e, -92a, and -130a) were validated by TaqMan-based stem-loop qPCR. Among them, miR-210, which has been reported to down regulate DNA homology-dependent repair (HDR) pathways through RAD52 gene, was upregulated in MSI ECs. Two additional potential targets involved in DNA damage repair system, ALKBH3 (alkylation repair homolog 3, in E. coli) and DDI2 (DNA-damage inducible 1 homolog 2), were identified and confirmed by in vivo assays. An inverse correlation between the expression of miR-210 and expression of ALKBH3 or DDI2 mRNA was observed in EC samples.
Conclusions: MicroRNAs are differentially expressed in MSI-high ECs. Increased expression of miR-210 may contribute to the pathogenesis of MSI-high ECs by downregulating genes that are involved in DNA damage repair.
Category: Special Category - Pan-genomic/Pan-proteomic approaches to Cancer
Monday, February 28, 2011 1:00 PM
Poster Session II # 248, Monday Afternoon