Endocrine Abstracts

Introduction: miR143 and 145 seem to be involved in the pathogenesis of cortitotrophinomas by modulating the expression of MAPK7 and CCNL1 genes, which protein products are involved in cell proliferation, differentiation, and cell cycle progression. Objective: To analyze the modulation of miR-143 and -145 in the expression of MAPK7 and CCNL1 genes in corticotrophinomas and corticotrophic tumoral lineage (AtT20).

Material and Methods: The expression of MAPK7 and CCNL1 was evaluated by Real Time PCR in 25 corticotrophinomas obtained from patients with Cushing’s disease and 6 normal anterior pituitaries and in primary culture of anterior pituitary cells and in AtT20 culture cells from mouse. Functional analyses of the interaction of miR-mRNAs were performed by the transfeccion of miR precursors in AtT20 cell lineage (siPORT, Applied Biosystems).

Results: We observed no differential expression of MAPK7 (0.94±0.36 vs 1.16±1.30) and CCNL1 (0.90±0.29 vs 0.64±0.51) genes between normal pituitaries and corticotrophinomas. We observed an overexpression of MAPK7 (3.61±1.84 vs 0.93±0.17, P=0.002) and CCNL1 (2.6±0.7 vs 0.99±0.08, P=0.002) in AtT20 cells compared to primary pituitary culture cells. The transfections were confirmed by overexpression of miR143 (1.25±0.79 vs 1552±730, P<0.0001) and miR145 (1.43±1.42 vs 4567.6±1235, P=0.0003). We observed no differential expression of MAPK7/ERK5 gene neither with miR-143 (1.04±0.2 vs 1.07±0.02) nor with miR-145 (1.04±0.2 vs 1.13±0.2) in AtT20 transfected cells. There was also no differential expression in CCNL1gene in AtT20 cell transfected with miR143 (1.05±0.3 vs 1.05±0.3); however, there was CCNL1 overexpression (1.05±0.3 vs 1.17±0.2;P=0.003) in AtT-20 transfected cells with miR145.

Conclusion: The differential expression between corticotrophinomas and AtT-20 tumoral culture cells may be due to culture immortalization. The interaction of miR-143 and MAPK7 gene does not occur by mRNA degradation, suggesting a posttranscriptional event. miR-145 may up regulate CCNL1 gene, which might lead to deregulation of the cell cycle and contribute to the pathogenesis of corticotrophinomas.

Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.

Funding: This work was supported, however funding details unavailable.