GHB promotes GBM and DIPG stem-like cell differentiation and decreases tumor burden.
a Positive and negative correlation of
ALDH5A1 and
AKR7A2 expression with stemness genes (
p < 0.01 after correction for multiple testing with false discovery rate). Gene ontology (GO) analysis using transcriptomes of 484 untreated primary human GBM of the TCGA dataset. Of the 142 listed in KEGG pathway category «Signaling pathways regulating pluripotency of stem cells» , 122 were detected in the dataset. 61 were significantly correlated with
ALDH5A1 (48 positive/13 negative) and 38 with
AKR7A2 (3 positive/35 negative).
b Opposite regulation of
ALDH5A1 and
AKR7A2 transcript levels in cells with and without self-renewing and tumor-initiating properties (SR/TI) isolated from 4 human GBM [
32]. Mean ± SD.
c–
h GHB inhibits Nanog expression.
c Examples of immunocytochemical detection of Nanog. 1-week GHB 10 mM.
Scale bars 10 µm. (
d) Quantification of nuclear Nanog immunofluorescent (IF) signal. Mean ± SD,
n = 3 independent biological samples. Microphotographs illustrate 240 nm single optical sections of TG1 cells immunostained for Nanog.
e Decreased Nanog expression in response to
ALDH5A1 downregulation. siA,
ALDH5A1 siRNA. siC, control siRNA. Mean ± SD,
n = 4 independent biological samples.
f Nanog Western blot assay with protein extracts from control (Cont) and 10 mM GHB-treated TG1 GBM stem-like cells (1-week treatment). Nanog MW, 47 kDa; Actin MW, 42 kDa.
n = 3 independent biological samples. RDU, relative densitometry units.
g FACS analysis of Nanog immunofluorescent signal.
Grey and
red lines delineate unstained TG1 cells in control and GHB-treated conditions, respectively.
h Fold change of mean fluorescent intensity of Nanog signal per cell (control vs 1 week-GHB 10 mM), as determined by FACS. TG1 and R633 GBM stem-like cells. TP83 DIPG stem-like cells. Mean ± SD,
n = 4 independent biological samples.
i GHB promotes cell adherence and membrane extension. Microphotograph of TG1 GBM stem-like treated with 10 mM GHB for 24 h and quantification of the numbers of adhering cells. Mean ± SD,
n = 6 independent biological samples (TG1),
n = 3 (5706**),
n = 3 (TP83).
Scale bar 100 µm.
j Bioluminescent analyses of tumor growth initiated by grafting 6240** GBM stem-like cells transduced with a luciferase construct and a control (shC) or
ALDH5A1 (shA) shRNA construct. 49 days post-graft. Quantification of the bioluminescent signals. Mean ± SD,
n = 15 mice per group. Photographs correspond to examples of bioluminescent in vivo images of tumors in mice.
k Quantification of tumor cells numbers following xenografts of GFP-expressing 5706** GBM or TP54 DIPG stem-like cells transduced with a control or
ALDH5A1 shRNA construct. Mice were killed at 64 (5706**) or 71 (TP54) days post-graft, and the numbers of GFP-expressing cells determined. Mean ± SD,
n = 3 (5706**) and 4 mice (TP54) per group