Different response of Ptch mutant and Ptch wildtype Rhabdomyosarcoma toward SMO and PI3K inhibitors

  • Rhabdomyosarcoma (RMS) is the most common pediatric soft tissue sarcoma with poor prognosis. RMS frequently show Hedgehog (HH) pathway activity, which is predominantly seen in the embryonal subtype (ERMS). They also show activation of Phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K) signaling. Here we compared the therapeutic effectiveness and the impact on HH target gene expression of Smoothened (SMO) antagonists with those of the PI3K inhibitor pictilisib in ERMS with and without mutations in the HH receptor Patched1 (PTCH). Our data demonstrate that growth of ERMS showing canonical Hh signaling activity due to Ptch germline mutations is efficiently reduced by SMO antagonists. This goes along with strong downregulation of the Hh target Gli1. Likewise Ptch mutant tumors are highly responsive toward the PI3K inhibitor pictilisib, which involves modulation of AKT and caspase activity. Pictilisib also modulates Hh target gene expression, which, however, is rather not correlated with its antitumoral effects. In contrast, sporadic ERMS, which usually express HH target genes without having PTCH mutation, apparently lack canonical HH signaling activity. Thus, stimulation by Sonic HE (SHH) or SAG (Smoothened agonist) or inhibition by SMO antagonists do not modulate HH target gene expression. In addition, SMO antagonists do not provoke efficient anticancer effects and rather exert off-target effects. In contrast, pictilisib and other PI3K/AKT/mTOR inhibitors potently inhibit cellular growth. They also efficiently inhibit HH target gene expression. However, of whether this is correlated with their antitumoral effects it is not clear. Together, these data suggest that PI3K inhibitors are a good and reliable therapeutic option for all ERMS, whereas SMO inhibitors might only be beneficial for ERMS driven by PTCH mutations.

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Author:Natalie Geyer, Rosalie Ridzewski, Julia Bauer, Maria Kuzyakova, Kai Dittmann, Christian Dullin, Albert Rosenberger, Hans-Ulrich Schildhaus, Anja Uhmann, Simone FuldaORCiDGND, Heidi Hahn
Pubmed Id:https://pubmed.ncbi.nlm.nih.gov/30319965
Parent Title (English):Frontiers in oncology
Publisher:Frontiers Media
Place of publication:Lausanne
Contributor(s):Anat Erdreich-Epstein
Document Type:Article
Year of Completion:2018
Date of first Publication:2018/09/25
Publishing Institution:Universitätsbibliothek Johann Christian Senckenberg
Release Date:2018/10/18
Tag:ERMS; HH; HhAntag; PI3K; PTCH; pictilisib; sonidegib; vismodegib
Issue:Art. 396
Page Number:11
First Page:1
Last Page:11
Copyright © 2018 Geyer, Ridzewski, Bauer, Kuzyakova, Dittmann, Dullin, Rosenberger, Schildhaus, Uhmann, Fulda and Hahn. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
Institutes:Medizin / Medizin
Dewey Decimal Classification:6 Technik, Medizin, angewandte Wissenschaften / 61 Medizin und Gesundheit / 610 Medizin und Gesundheit
Licence (German):License LogoCreative Commons - Namensnennung 4.0