Rapamycin promotes differentiation increasing βIII-tubulin, NeuN, and NeuroD while suppressing nestin expression in glioblastoma cells

// Michela Ferrucci 1,* , Francesca Biagioni 2,* , Paola Lenzi 1 , Stefano Gambardella 2 , Rosangela Ferese 2 , Maria Teresa Calierno 2 , Alessandra Falleni 3 , Alfonso Grimaldi 4 , Alessandro Frati 2 , Vincenzo Esposito 2,4 , Cristina Limatola 2,4 , Francesco Fornai 1,2 1 Department of Translational Research and New Technologies in Medicine and Surgery, Human Anatomy, University of Pisa, Pisa, Italy 2 Istituto di Ricovero e Cura a Carattere Scientifico, Neuromed, Pozzilli, Isernia, Italy 3 Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy 4 Department of Physiology and Pharmacology, La Sapienza University of Rome, Roma, Italy * These authors equally contributed to the manuscript Correspondence to: Francesco Fornai, email: // Keywords : mammalian target of rapamycin; stem cells; neuronal differentiation; transmission electron microscopy; qRT-PCR; Gerotarget Received : September 27, 2016 Accepted : February 21, 2017 Published : March 18, 2017 Abstract Glioblastoma cells feature mammalian target of rapamycin (mTOR) up-regulation which relates to a variety of effects such as: lower survival, higher infiltration, high stemness and radio- and chemo-resistance. Recently, it was demonstrated that mTOR may produce a gene shift leading to altered protein expression. Therefore, in the present study we administered different doses of the mTOR inhibitor rapamycin to explore whether the transcription of specific genes are modified. By using a variety of methods we demonstrate that rapamycin stimulates gene transcription related to neuronal differentiation while inhibiting stemness related genes such as nestin. In these experimental conditions, cell phenotype shifts towards a pyramidal neuron-like shape owing long branches. Rapamycin suppressed cell migration when exposed to fetal bovine serum (FBS) while increasing the cell adhesion protein phospho-FAK (pFAK). The present study improves our awareness of basic mechanisms which relate mTOR activity to the biology of glioblastoma cells. These findings apply to a variety of effects which can be induced by mTOR regulation in the brain. In fact, the ability to promote neuronal differentiation might be viewed as a novel therapeutic pathway to approach neuronal regeneration.