miRNA-mediated Drug Repurposing Unveiled Potential Candidate Drugs for Prolactinoma Treatment.

INTRODUCTION Prolactinomas, also called lactotroph adenomas, are the most encountered type of hormone-secreting pituitary neuroendocrine tumors (PitNET) in the clinic. The preferred first-line therapy is a medical treatment with dopamine agonists (DA), mainly cabergoline, to reduce serum prolactin levels, tumor volume, and mass effect. However, in some cases, patients have displayed DA-resistance with aggressive tumor behavior or are faced with recurrence after drug withdrawal. Also, currently used therapeutics have notorious side effects and impair the life quality of the patients. METHODS Since the amalgamation of clinical and laboratory data besides tumor histopathogenesis and transcriptional regulatory features of the tumor emerge to exhibit essential roles in the behavior and progression of prolactinomas, in this work, we integrated mRNA and microRNA (miRNA) level transcriptome data that exploit disease-specific signatures in addition to biological and pharmacological data to elucidate a rational prioritization of pathways and drugs in prolactinoma. RESULTS We identified eight drug candidates through drug repurposing based on mRNA-miRNA level data integration and evaluated their potential through in vitro assays in the MMQ cell line. Seven re-purposed drugs including 5-flourocytosine, nortriptyline, neratinib, puromycin, taxifolin, vorinostat, and zileuton were proposed as potential drug candidates for the treatment of prolactinoma. We further hypothesized possible mechanisms of drug action on MMQ cell viability through analyzing PI3K/Akt signaling pathway and cell cycle arrest via flow cytometry and western blotting. DISCUSSION We presented the transcriptomic landscape of prolactinoma through miRNA and mRNA level data integration and proposed repurposed drug candidates based on this integration. We validated our findings through testing cell viability, cell cycle phases, and PI3K/Akt protein expressions. Effects of the drugs on cell cycle phases and inhibition of PI3K/Akt pathway by all drugs gave us promising output for further studies using these drugs in the treatment of prolactinoma. This is the first study that reports miRNA-mediated repurposed drugs for prolactinoma treatment via in vitro experiments.