miR-26a targets PRKCD in ACTH pituitary adenoma
E. Gentilin, F. Tagliati, E. degli Uberti & M. Zatelli
MicroRNAs (miRNAs) have several physiological functions, but have been also implicated in human neoplastic initiation and progression. We previously demonstrated that 30 miRNAs are differentially expressed in normal human pituitary as compared to pituitary adenomas. However, the most of miRNAs target genes remain unknown, hindering the understanding of the miRNAs contribute to pituitary tumorigenesis.
The aims of this study were to: (i) validate a murine ACTH-secreting pituitary adenoma cell line as a possible model to study pituitary miRNA deregulation; (ii) validate and investigate the role of potential targets of differentially expressed miRNAs. We analysed the murine AtT-20/D16v-F2 cell line, deriving from a murine ACTH-secreting pituitary adenoma, and normal mouse pituitary for the expression pattern of 11 miRNA, which expression was found to be different in human pituitary adenomas vs normal pituitary. Our results showed a partial agreement (50%) between expression trend of these miRNAs in human and mouse. In particular, we found that miR-26a has overlapping expression patterns in humans and mice, being up-regulated in adenomas vs. normal pituitary. Our results confirm that the 3′ untranslated region of PRKCD, a miR-26a putative target gene, is a functional target of this miRNA and provide evidence, by Real Time PCR, that this target is translationally suppressed. PRKCD, a member of the PKC subfamily, is dynamically involved in cell apoptosis in a specific stimulus manner. We observed that miR-26a inhibition led to a decrease in cell viability without increasing caspase 3/7 activity. These results indicate that miR-26a is overexpressed in human ACTH pituitary adenoma and can control cell viability in AtT-20/D16v-F2 cell line, by reducing the PRKCD expression, playing an important role in pituitary adenoma development. Our study provides new insights into potential contribution of these RNAs to pituitary neoplastic transformation and suggests that miR-26a might be a possible target for therapeutic strategies.
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 research did not receive any specific grant from any funding agency in the public, commercial or not-for-profit sector.