MEOX2 promotes glioma growth and temozolomide chemoresistance

Abstract

Image 1.

Graphical abstract

Fig. 1

Mesenchyme homeobox 2 (MEOX2) is positively associated with glioma malignancy, and regulates temozolomide (TMZ) chemoresistance. (A) Correlation between MEOX2 expression and glioma histological features and prognostic biomarkers in The Cancer Genome Atlas (TCGA) dataset (n = 681). (B) Kaplan-Meier survival analysis using clinical information from the TCGA dataset. Patients are divided into low and high MEOX2 groups by median expression level (n = 681). (C) Real-time quantitative polymerase chain reaction (RT-qPCR) analysis of messenger RNA (mRNA) expression in paired glioblastoma (GBM) tissues. Results are shown as mean ± standard deviation (SD) (n = 20). (D) Western blots of representative 4 pairs of GBM and adjacent tissues. (E) Quantifications of MEOX2 expression in 21 pairs of GBM and peritumor tissues (mean ± SD). (F, G) Cell Counting Kit-8 (CCK-8) assay showing that MEOX2 overexpression (OE) increased cell numbers compared with control (F), and MEOX2 knockdown (KD) decreased cell numbers in KNS89 cells (G) (n = 3). (H, I) Hematoxylin and eosin (H&E) staining of intracranial xenograft tumor in nude mice with KNS89 cells (H) and the maximal coronal sectional area of tumors (I) (n = 5 per group). (J, K) Image (J) and quantification (K) of Hoechst staining showing that MEOX2 OE decreased TMZ-induced apoptosis of KNS89 cells (400 or 600 μM, 48 h) (n = 3). (L) Western blots indicated that phosphorylation of protein kinase B (AKT) at both Ser473 and Thr308 were inhibited in MEOX2 OE/control cells by 2 μM MK-2206 in U87MG cells. (M, N) Hoechst staining (M) and quantification (N) of MEOX2 OE/control cells treated by combination of TMZ and vehicle (dimethyl sulfoxide (DMSO)) or TMZ and an AKT inhibitor MK-2206 showed that TMZ resistance effect of MEOX2 OE was antagonized by MK-2206 (n = 3). ∗P < 0.05, ^∗∗P < 0.01, and ^∗∗∗P < 0.0001, based on paired Student's t-test. n.s.: not significant. WHO: World Health Organization; IDH: isocitrate dehydrogenase; MGMT: methylguanine DNA methyltransferase; WT: wildtype; NA: not available; NC: negative control; p-AKT: phospho-AKT; t-AKT: total AKT.