Increased LGALS3 expression independently predicts shorter overall survival in patients with the proneural subtype of glioblastoma

Abstract

In the current study, we tried to study the expression of LGALS3 and LGALS3BP, their potential as prognostic markers and the possible genetic/epigenetic mechanisms underlying their dysregulation in different subtypes of glioblastoma (GBM). An in silico retrospective study was performed using large online databases. Results showed that LGALS3 and LGALS3BP were upregulated at both RNA and protein levels in GBM tissue and were generally associated with shorter overall survival (OS) in GBM patients. However, in subgroup analysis, we only found the association in proneural subtype. The copy number alterations did not necessarily lead to LGALS3/LGALS3BP dysregulation. In the proneural subtype of GBM patients, hypermethylation of the two CpG sites (cg19099850 and cg17403875) was associated with significantly lower expression of LGALS3. In univariate and multivariate analysis, LGALS3 expression independently predicted shorter OS in the proneural subtype of GBM (HR: 1.487, 95% CI: 1.229-1.798, P < 0.001), after adjustment of age, gender, IDH1 mutations, temozolomide chemotherapy, radiotherapy and LGALS3BP expression. In comparison, LGALS3BP lost the prognostic value in multivariate analysis. Based on these findings, we infer that LGALS3 expression serves as an independent biomarker of shorter OS in the proneural subtype of GBM, the expression of which might be regulated in an epigenetic manner.

Keywords: LGALS3; LGALS3BP; glioblastoma; proneural subtype.

Figure 1

The expression profile of LGALS3 and LGALS3BP in glioblastoma (GBM) tissues and the adjacent normal tissues. A, Heatmap showing the expression of LGALS3 and LGALS3BP in GBM tissues and the adjacent normal tissues. B‐E, Plot charts comparing the expression of LGALS3 (B and D) and LGALS3BP (C and E) between GBM tissues and the adjacent normal tissues (B‐C) and among the four subtypes of GBM (D‐E)

Figure 2

LGALS3 and LGALS3BP protein expression in normal brain tissues and in glioblastoma (GBM) tissues. IHC staining of LGALS3 (up) and LGALS3BP (down) protein expression in normal brain tissues (left, including cerebral cortex and hippocampus) and in GBM tissues. Images credit: The Human Protein Atlas. Images and protein scoring were obtained from: v18.proteinatlas.org, via: https://www.proteinatlas.org/ENSG00000131981-LGALS3/tissue/cerebral+cortex; https://www.proteinatlas.org/ENSG00000131981-LGALS3/tissue/hippocampus; httpsihc://www.proteinatlas.org/ENSG00000131981-LGALS3/pathology/tissue/glioma#ihc; https://www.proteinatlas.org/ENSG00000108679-LGALS3BP/tissue/cerebral+cortex; https://www.proteinatlas.org/ENSG00000108679-LGALS3BP/tissue/hippocampus and https://www.proteinatlas.org/ENSG00000108679-LGALS3BP/pathology/tissue/glioma#ihc

Figure 3

LGALS3/LGALS3BP expression and overall survival (OS) of glioblastoma (GBM). A and B, Plot charts comparing LGALS3 (A)/LGALS3BP (B) expression between the living and deceased GBM cases in TCGA‐GBM. C and D, Kaplan‐Meier curves of OS in GBM patients in TCGA‐GBM. Patients were separated into two groups according to the best cutoff of LGALS3 (C)/LGALS3BP (D) expression identified in the ROC analysis for death detection. E and F, Kaplan‐Meier curves of OS in GBM patients in GSE16011 from GEO datasets.27 Patients were separated into two groups according to the best cutoff of LGALS3 (E)/LGALS3BP (F) expression

Figure 4

LGALS3/LGALS3BP expression and overall survival (OS) of glioblastoma (GBM) subtypes. A‐H, Kaplan‐Meier curves of OS in the 4 molecular subtypes of GBM patients in TCGA‐GBM. Patients were separated into two groups according to the best cutoff of LGALS3 (A‐D)/LGALS3BP (E‐H) expression identified in the ROC analysis of death detection

Figure 5

The correlation between LGALS3/LGALS3BP expression and their DNA CNAs and IDH1 mutations in proneural glioblastoma (GBM). A and B, Heatmaps showing the correlation between LGALS3(A)/LGALS3BP(B) expression and their DNA CNAs and IDH1 mutations in proneural subtype. C and D, Plot charts comparing LGALS3(C)/LGALS3BP(D) in groups with different DNA CNAs. E and F, Plot charts comparing LGALS3(E)/LGALS3BP(F) in groups with or without IDH1 mutations

Figure 6

The correlation between LGALS3/LGALS3BP expression and their DNA methylations in proneural glioblastoma (GBM). A and B, Heatmaps showing the correlation between LGALS3(A)/LGALS3BP(B) expression and their DNA methylations in proneural subtype. C and D, Plot charts comparing LGALS3(C)/LGALS3BP(D) in groups with different DNA CNAs. E and F, Kaplan‐Meier curves of overall survival (OS) in the proneural subtype of GBM patients in TCGA‐GBM. Patients were separated into two groups according to the median methylation level of the two CpG sites of LGALS3(E)/LGALS3BP(F) measured in methylation 27k