Endocrine Abstracts

Background: Multiple endocrine neoplasia of type 1 (MEN1) is a rare heritable endocrine tumor syndrome that results from biallelic inactivation of the MEN1 gene and the loss of menin protein, that was characterized by a susceptibility to the development of multiple endocrine neoplasms within a single patient. The MEN1 gene screening is helpful in the clinical practice for early genetic diagnosis. Unfortunately, the lack of genotype-phenotype correlation doesn’t allow to foresee the syndrome’s clinical course, consequently, reducing the possibility to develop a personalized diagnostic and therapeutic plan. Recently, it has been reported that menin is capable to suppress the Hedgehog signalling pathway (Hh) MEN1-dependent tumors and its loss might cause the over-activation of this proliferative and oncogenic pathway. Moreover, emerging evidence highlight that Hh pathway and MEN1 tumorigenesis could be under the control of epigenetic mechanisms, including miRNAs. In addition, results obtained over the last years demonstrated that cannabinoids regulate miRNA expression in BV-2 microglial cells and are endogenous conserved inhibitors of the Hedgehog (Hh) pathway. However, no data are currently available on the relationship between the endocannabinoid system (ES), Hh pathway, and miRNAs in MEN1 syndrome.

Materials and methods: First, in silico analyses, using TargetScan, miRanda, and miRNet software, were performed to find the possible binding between miRNAs and different factors involved in the Hh pathway. Next, cell biology analyses were carried out for a preliminary assessment of the ES components expression in different neuroendocrine tumor cells (i.e., insulinomas, gastrinomas, and prolactinomas) derived from MEN1 patients. Finally, we observed the effects of Anandamide (AEA) on insulinoma cells proliferation.

Results and future perspective: In silico analysis indicated the 3’ untranslated region (3’UTR) of human Dual specificity tyrosine phosphorylation regulated kinase 2 (DYRK2) mRNA as potential target of miR-24-1-3p, which was deregulated in MEN1 parathyroids and pancreas tumors. Then, PCR analysis showed the presence in the neuroendocrine tumor cells of both receptors (i.e., CNR1, CNR2, GPR55, GPR6, and TRPV1) and enzymes (i.e., FAAH, NAPE e DAGLα) involved in ES. Finally, we observed that treatment with different concentrations of AEA on insulinoma cells led to a decrease in their proliferative capacity, especially with 10 μM and 100nM concentrations. Further studies are needed to validate the latter finding and to subsequently establish the relationship between ES, miRNAs, Hh pathway, and MEN1 tumorigenesis. In conclusion, this project could pave the way for the possible future endocannabinoid-based drug development against MEN1 syndrome.