Objective:

2

To investigate the mechanistic basis for the anti-proliferation and anti-invasion effect of tumor necrosis factor-related apoptosis-induced ligand (TRAIL) and celastrol combination treatment (TCCT) in glioblastoma cells.

Methods:

2

Cell counting kit-8 was used to detect the effects of different concentrations of celastrol (0–16 μmol/L) and TRAIL (0–500 ng/mL) on the cell viability of glioblastoma cells. U87 cells were randomly divided into 4 groups

namely control

TRAIL (TRAIL 100 ng/mL)

Cel (celastrol 0.5 μmol/L) and TCCT (TRAIL 100 ng/mL + celastrol 0.5 μmol/L). Cell proliferation

migration

and invasion were detected by colony formation

wound healing

and Transwell assays

respectively. Quantitative reverse transcription polymerase chain reaction and Western blotting were performed to assess the levels of epithelial-mesenchymal transition (EMT) markers (zona occludens

N-cadherin

vimentin

zinc finger E-box-binding homeobox

Slug

and β-catenin). Wnt pathway was activated by lithium chloride (LiCl

20 mol/L) and the mechanism for action of TCCT was explored.

Results:

2

Celastrol and TRAIL synergistically inhibited the proliferation

migration

invasion

and EMT of U87 cells (

P

<

0.01). TCCT up-regulated the expression of GSK-3β and down-regulated the expression of β-catenin and its associated proteins (

P

<

0.05 or

P

<

0.01)

including c-Myc

Cyclin-D1

and matrix metalloproteinase (MMP)-2. In addition

LiCl

an activator of the Wnt signaling pathway

restored the inhibitory effects of TCCT on the expression of β-catenin and its downstream genes

as well as the migration and invasion of glioblastoma cells (

P

<

0.05 or

P

<

0.01).

Conclusions:

2

Celastrol and TRAIL can synergistically suppress glioblastoma cell migration

invasion

and EMT

potentially through inhibition of Wnt/β-catenin pathway. This underlies a novel mechanism of action for TCCT as an effective therapy for glioblastoma.