Expression of SOXC cluster and mir-17-92 polycistron in mantle cell lymphoma patients.

ALEJANDRO ROISMAN; FERNANDA METREBIAN; DANA KOHAN; HERNÁN GARCÍA RIVELLO; MARINA NARBAITZ; ELIAS CAMPO; LUIS HERNÁNDEZ; IRMA SLAVUTSKY

Viena

Congreso; 20th Congress of the European Hematology Association; 2015

European Hematology Association

Background: Mantle cell lymphoma (MCL) is an aggressive B-cell lymphoid malignancy that accounts for approximately 6% of all non-Hodgkin´s lymphomas. SOX4, SOX11 and SOX12 genes, constitute the SOXC family of transcription factors involved in embryonic neurogen­esis and tissue remodeling. Among them, SOX11 shows aberrant expression in MCL, being considered a new molecular marker of adverse prognosis in this pathology; meanwhile recently it has shown that SOX4 can bind and regulate the promoter of Dicer, a microRNA biogenesis factor. Furthermore, several studies have demonstrated the oncogenic role of miR-17-92 cluster in hematological malignancies, being scarce the information about the association between this cluster and SOXC expression levels in MCL.  Aims: In this study, we have performed a Gene Expression Analysis (GEA) of SOXC cluster and their correlation with the expression of miR-17, miR18a, miR19b and miR92a, members of the polycistronic oncomiR-17-92 in MCL patients. Methods: mRNA samples of 45 MCL patients (15 males; mean age: 56.7 years, range: 34-71 years) and 12 normal controls were analyzed. Gene expression was quantified by real time PCR using TaqMan Gene Expression Assays. GUSB and RNU6B were used as housekeeping genes to normalize the expression of SOXC and miR17-92 clusters, respectively. The proliferation index was evaluated by immunohistochemistry with the Ki67 antibody. The analysis of mRNA expression data was done using the two-tailed Mann-Withney test. To calculate the expression cut-off values with the highest sensitivity and specificity, receiver operating characteristics curves were used. The study was approved by the Ethics Committee of our Institution. All individuals gave their informed consent. Results: The analysis of SOXC members showed upregulation, of SOX11 and SOX12 in 60% and 71% patients, respectively, while SOX4 was downregulated in 45% of cases, compared to normal controls. GEA of SOX11 and SOX12 showed higher expression levels (2.1±0.24 and 3.1±0.16, respectively), with respect to SOX4 (1.2 ±0.21) (p=0,006 and p<0.0001, respectively). Moreover, an inverse relationship between the expression of SOX11 and SOX4 was detected (p=0.0017), being the last one undetectable in patients with high expression of SOX11. Regarding to the members of the miR17-92 cluster, miR17 and miR18a were downregulated in 86% and 84.4% of our cohort, respectively; meanwhile, miR19b and miR92a were upregulated in 95% of cases each, compared to controls. GEA revealed that miR19a (3.24±0.1) and miR92a (2.59±0.1) exhibited increased expression levels than miR17 (-2.7±0.15) and miR18a (-2.8±0.19) (p<0.0001). A positive correlation between miR92a with miR17 (p=0.0001), miR18a (p=0.0013), and miR19b (p<0.0001) mRNA levels, was observed. Moreover, we found a positive correlation between SOXC members and miR18a expression (p<0,012). In addition, patients overexpressing SOX11, SOX12 and miR92a showed a higher percentage of Ki67 positive cells (37-41%), compared to cases without expression, but without reaching significant differences. Conclusions: Our findings in MCL patients show for the first time an inverse correlation in the expression profiles of SOX11 and SOX4 genes. Additionally, and to the best of our knowledge, we found new evidence linking the differential expression pattern between SOXC genes and miR18a, suggesting an interaction that could add new insights in the biologic characterization of this pathology.