Pro-Angiogenic Mir-296 Is Frequently Overexpressed and Is Associated with Advanced Stage Disease in Diffuse Large B-Cell Lymphoma

MicroRNAs (miRNAs) are a class of endogenous short non-coding RNAs that control gene expression by acting on target mRNAs for promoting either their degradation or translational repression. Some of them have involvement in regulating various aspects of angiogenesis, including proliferation, migration and morphogenesis of endothelial cells, which are important in regulating cardiovascular development and cancer. The term “angiomiR” is used to define the miRNAs that control angiogenesis. They are classified into pro-angiomiRs, those that promote angiogenesis, and anti-angiomiRs, those that inhibit angiogenesis. The identification of angiomiRs as the key to regulating angiogenesis has opened new paths in the treatment of vascular and oncology diseases.

This study aims to analyze the expression angiomiRs in diffuse large B-cell lymphoma (DLBCL) and to correlate them with clinical and histological features to identify possible biomarkers and prognostic factors.

We studied 93 samples of de novo DLBCL diagnosed between 2000 and 2010. All the cases were HIV-negative. MicroRNAs were obtained from paraffin embedded tumor samples using RecoverAll™ Total Nucleic Acid Isolation Kit for FFPE Tissues (Applied Biosystems). Four angiomiRs (miR-378, miR-296, miR-210 and miR-126) were analyzed. RNU44 and U18 were used as endogenous controls for quantitative PCR (TaqMan^®Small RNA Assays). We set a threshold of a 1.5-fold difference in angiomiRs expression compared to controls (palatine tonsil).

miR-378, miR-296, miR-210 and miR-126 overexpression were observed in 43%, 47%, 22% and 5%, respectively. Considering that miR-378 and miR-296 were frequently overexpressed in DLBCL, we further analyzed the following variables: age (<=60 versus >60 years), Ann Arbor Staging System (I-II versus III-IV), International Prognostic Index (0–2 versus 3–5), DLBCL classification (NOS versus subtypes), tumor origin according to Hans (2004) algorithm (GCB versus non-GCB). We observed higher median miR-296 expression in DLBCL classified as stage III-IV (p = 0.0415, Mann-Whitney). For the other variables, were did not find any statistically significant difference between groups.

miR-296, that directly decreased the levels of hepatocyte-growth factor regulated tyrosine kinase substrate (HGS) and indirectly upregulate VEGFR2 and PDGFRβ, was overexpressed in almost 50% of de novo DLBCL and was associated with advanced stage disease. Our study brings new information about the role of microRNA importance in DLBCL development and can be explored as prognostic and therapeutic target for patients suffering from this prevalent malignancy (Supported by FAPESP 2010/17668-6).

No relevant conflicts of interest to declare.