Target Genes Associated with Micro RNA Profiles in Patients with Chronic Lymphocytic Leukemia
Swati Srivastava, Heather Steinmetz, Gregory J Tsongalis, Prabhjot Kaur. Dartmouth Medical School, Dartmouth Hitchcock Medical Center, Norris Cotton Cancer Center, Lebanon, NH
Background: Chronic lymphocytic leukemia (CLL) is a heterogeneous disease that needs better prognostic biomarkers. MicroRNAs (miR) are 22-nucleotide, endogenous, non-coding regulatory RNAs that modulate hematopoietic lineage differentiation and play important gene-regulatory roles in disease processes. In this study, we evaluated expression of eight miRNAs and identified potential target genes that may be dysregulated by these miRNAs in the development of CLL.
Design: In the present study, 60 RNA samples, obtained from 60 CLL cases, were extracted from fresh peripheral blood samples. The patient's ages ranged from 46 to 90 years. Samples were collected at different time points between August 2009 and June of 2011. They were enriched for B-cells using the RosetteSep Human B Cell Enrichment Cocktail (StemCell Technologies, Vancouver, BC, Canada) and total RNA was extracted using the mirVana™ miRNA Isolation Kit (Ambion). Expression of miR15a, miR16-1, miR29a, miR181a, miR 21, miR 29c, miR 155 and miR 223 and U47 (an endogenous control) in each sample was determined using TaqMan® MicroRNA Assays (Applied Biosytems). In addition, expression of these miRNAs was determined in B cells from normal samples. The DCT of the normal (CTnormal - CTendogenous control) and CLL samples (CTCLL sample - CTendogneous control) were calculated, and relative comparison of normal and CLL samples was made using the DDCTmethod (DCTCLL sample - DCTnormal).
Results: In this study, we found that there is a downregulation of miR 15a in 25%, miR 16-1 in 20%, miR 29a in 25%, miR 181a in 95%, miR 21 in 10% and up-regulation of miR 21 in 90%, miR 155 in 50% and miR29c in 90% of cases. Interestingly, miR 181a was downregulated in all CLL cases compared to normal. Using TargetScanHuman 5.2, we identified in silico potential target genes whose expression would be dysregulated by these miRNAs in the development of CLL. These included BCL2 and genes involved in the regulation of Tumor necrosis factor.
Conclusions: Our data support the role of abnormal miRNA expression in the development of CLL and the potential for this information to serve as a surrogate prognostic marker for this disease. In addition, target genes regulated by these miRNAs have been shown to play important roles in CLL disease progression further supporting the role of miRNAs as significant biomarkers in CLL.
Tuesday, March 20, 2012 11:00 AM
Platform Session: Section C, Tuesday Morning