Penfluridol suppresses glioblastoma tumor growth by Akt-mediated inhibition of GLI1

// Alok Ranjan 1 , Sanjay K. Srivastava 1, 2 1 Department of Biomedical Sciences and Cancer Biology Center, Texas Tech University Health Sciences Center, Amarillo, TX 79106, USA 2 Department of Immunotherapeutics and Biotechnology, Texas Tech University Health Sciences Center, Abilene, TX 79601, USA Correspondence to: Sanjay K. Srivastava, email: sanjay.srivastava@ttuhsc.edu Keywords: antipsychotic drug, glioblastoma, neurosphere, in vivo, intracranial Received: December 16, 2016      Accepted: March 03, 2017      Published: March 23, 2017 ABSTRACT Glioblastoma (GBM) is the most common brain tumor with poor survival rate. Our results show that penfluridol, an antipsychotic drug significantly reduced the survival of ten adult and pediatric glioblastoma cell lines with IC 50 ranging 2–5 μM after 72 hours of treatment and induced apoptosis. Penfluridol treatment suppressed the phosphorylation of Akt at Ser473 and reduced the expression of GLI1, OCT4, Nanog and Sox2 in several glioblastoma cell lines in a concentration-dependent manner. Inhibiting Akt with LY294002 and siRNA, or inhibiting GLI1 using GANT61, cyclopamine, siRNA and CRISPR/Cas9 resulted in enhanced cell growth suppressive effects of penfluridol. On the other hand, overexpression of GLI1 significantly attenuated the effects of penfluridol. Our results further demonstrated that penfluridol treatment inhibited the growth of U87MG tumors by 65% and 72% in subcutaneous and intracranial in vivo glioblastoma tumor models respectively. Immunohistochemical and western blot analysis of tumors revealed reduced pAkt (Ser 473), GLI1, OCT4 and increase in caspase-3 cleavage and TUNEL staining, confirming in vitro findings. Taken together, our results indicate that overall glioblastoma tumor growth suppression by penfluridol was associated with Akt-mediated inhibition of GLI1.