FTY720 Decreases Tumorigenesis in Group 3 Medulloblastoma Patient-Derived Xenografts

Evan F Garner,Elizabeth A Beierle,Jerry E Stewart,Blake P Moore,Elizabeth Mroczek-Musulman,Gregory K Friedman,Adele P Williams,Jamie M Aye,Laura L Stafman

doi:10.1038/s41598-018-25263-5

Abstract

Group 3 tumors account for 28% of medulloblastomas and have the worst prognosis. FTY720, an immunosuppressant currently approved for treatment of multiple sclerosis, has shown antitumor effects in several human cancer cell lines. We hypothesized that treatment with FTY720 (fingolimod) would decrease tumorigenicity in medulloblastoma patient-derived xenografts (PDXs). Three Group 3 medulloblastoma PDXs (D341, D384 and D425) were utilized. Expression of PP2A and its endogenous inhibitors I2PP2A and CIP2A was detected by immunohistochemistry and immunoblotting. PP2A activation was measured via phosphatase activation kit. Cell viability, proliferation, migration and invasion assays were performed after treatment with FTY720. Cell cycle analysis was completed using flow cytometry. A flank model using D425 human medulloblastoma PDX cells was used to assess the in vivo effects of FTY720. FTY720 activated PP2A and led to decreased medulloblastoma PDX cell viability, proliferation, migration and invasion and G1 cell cycle arrest in all three PDXs. FTY720 treatment of mice bearing D425 medulloblastoma PDX tumors resulted in a significant decrease in tumor growth compared to vehicle treated animals. FTY720 decreased viability, proliferation, and motility in Group 3 medulloblastoma PDX cells and significantly decreased tumor growth in vivo. These results suggest that FTY720 should be investigated further as a potential therapeutic agent for medulloblastoma.

Highlights

FTY720 (2-Amino-2-[2-(4-octylphenyl)]-1,3-propanediol, fingolimod) is a synthetic sphingosine immunosuppressant that was approved by the United States Food and Drug Administration (FDA) for the treatment of multiple sclerosis[9,10]
IHC demonstrated that phosphatase 2A (PP2A) and its endogenous inhibitors, PP2A inhibitor 2 (I2PP2A/SET) and cancerous inhibitor of PP2A (CIP2A), were present in all three medulloblastoma patient-derived xenografts (PDXs) (Fig. 1A)
Following treatment of D341, D384, and D425 cells with FTY720 (5 μM) for 4 hours, the activity of PP2A was significantly increased over baseline relative to control in all three medulloblastoma PDX cell lines (Fig. 1C)

Summary

Introduction

FTY720 (2-Amino-2-[2-(4-octylphenyl)]-1,3-propanediol, fingolimod) is a synthetic sphingosine immunosuppressant that was approved by the United States Food and Drug Administration (FDA) for the treatment of multiple sclerosis[9,10]. FTY720 has been shown to have anti-tumor properties in several human malignancies[11,12,13], including glioblastoma[14,15,16]. FTY720 produces these effects through multiple proposed mechanisms, including activation of the tumor suppressor protein phosphatase 2A (PP2A)[17,18], down regulation of cyclin D119, inhibition of sphingosine kinase 1 (SphK1)[20,21], and generation of reactive oxygen species (ROS)[14,22,23]. Because of the anti-tumor properties of FTY720 seen in other human malignancies, we hypothesized that it may have anti-tumor effects on medulloblastoma. We demonstrated that FTY720 treatment led to decreased cell viability, migration and invasion, and caused cell cycle arrest and apoptosis in Group 3 medulloblastoma patient-derived xenografts (PDXs). FTY720 significantly decreased tumor growth in vivo in mice bearing Group 3 medulloblastoma

Methods

Results

Conclusion