Abstract 5275: miRNA profiling of peripheral T-cell lymphomas.
Authors: Laginestra Maria Antonella , Fuligni Fabio , Rossi Maura , Gibellini Davide , Sapienza Maria Rosaria , Gazzola Anna , Mannu Claudia , Sabattini Elena , Bacci Francesco , Agostinelli Claudio , Pileri Stefano Aldo , Piccaluga Pier Paolo 
Published: August 2014

Background: Peripheral T cell lymphomas not otherwise specified (PTCLs/NOS) are rare and aggressive tumors, whose molecular pathogenesis is poorly known and whose diagnosis is quite difficult. In fact, both morphology and phenotype largely overlap with those of other nodal PTCLs, including angioimmunoblastic T cell lymphoma (AITL) and anaplastic large cell lymphomas (ALCLs).

Here, we performed an extensive miRNA profiling of PTCLs in order to identify differentially expressed miRNA, either involved in their pathogenesis or potentially useful for their differential diagnosis.

Methods: We studied by miRNA profiling (TaqMan Array MicroRNA Cards A) 60 samples including PTCLs/NOS (N=25), AITLs (N=10), ALCLs (N=12) and normal T cells (N=13); in addition, 40 independent PTCL cases were studied by qRT-PCR as validation. Further, to assess the functional impact of deregulated miRNAs, we performed a global gene expression profile (GEP) analysis in the same cases by using the Illumina Whole Genome DASL Assay. ANOVA and Student t-test were performed to find genes and miRNAs differentially expressed between PTCLs and normal T cells or among PTCL subtypes, respectively. Differentially expressed miRNAs were further filtered based on their predicted impact on the GEP using Linear Discriminant Analysis, Spearman correlation and Gene Set Enrichment Analysis. A discriminant function based on linear combination of GEP signatures was then used to better distinguish different PTCLs subtypes. Finally, the functional effects of selected miRNA were assessed by transfection of specific mimic and inhibitors into PTCL cells and then evaluating the GEPs (functional GEP).

Findings: First, unsupervised analyses clearly discriminated PTCLs and normal T cells based on the miRNA expression patterns. Second, supervised analysis identified 256 miRNA differentiating the two groups (p&lt;0.05, FC ≥2, Bonferroni correction). To identify those miRNA more likely to impact the GEP of the tumors, we then performed a multi-step analysis integrating miRNA and GEP data. We identified 4 highly discriminant miRNA inversely correlated with different potential target genes. All 4 miRNA were confirmed by qPCR in a validation set, while their target genes were assessed by functional GEP confirming their impact.

Thereafter, we sought miRNAs differentially expressed in the PTCL subtypes, to be used as diagnostic markers. Based on ANOVA and subsequent linear discriminant analysis we identified 3 sets of miRNA able to efficiently distinguish PTCL/NOS vs. ALK-/ALCL (N=5 miRNA), ALK+/ALCL vs. ALK-/ALCL (N=4), and PTCL/NOS vs. AITL (N=8). Noteworthy, this novel molecular diagnostic tool was validated by qPCR in independent cases, demonstrating a remarkable diagnostic accuracy ranging between 85% and 95%.

In conclusion, miRNA profiling allowed to identify miRNA possibly involved in PTCL pathogenesis and to develop a novel diagnostic tool for the differential diagnosis of the commonest subtypes.

Citation Format: Maria Antonella Laginestra, Fabio Fuligni, Maura Rossi, Davide Gibellini, Maria Rosaria Sapienza, Anna Gazzola, Claudia Mannu, Elena Sabattini, Francesco Bacci, Claudio Agostinelli, Stefano Aldo Pileri, Pier Paolo Piccaluga. miRNA profiling of peripheral T-cell lymphomas. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 5275. doi:10.1158/1538-7445.AM2013-5275