Altered O-linked glycosylation in benign and malignant meningiomas

Abstract

Background: Changes in protein glycosylation have been reported in various diseases, including cancer; however, the consequences of altered glycosylation in meningiomas remains undefined. We established two benign meningioma cell lines-SUT-MG12 and SUT-MG14, WHO grade I-and demonstrated the glycan and glycosyltransferase profiles of the mucin-type O-linked glycosylation in the primary benign meningioma cells compared with two malignant meningioma cell lines-HKBMM and IOMM-Lee, WHO grade III. Changes in O-linked glycosylation profiles in malignant meningiomas were proposed.

Methods: Primary culture technique, morphological analysis, and immunocytochemistry were used to establish and characterize two benign meningioma cell lines. The glycan profiles of the primary benign and malignant meningiomas cell lines were then analyzed using lectin cytochemistry. The gene expression of O-linked glycosyltransferases, mucins, sialyltransferases, and fucosyltransferases were analyzed in benign and malignant meningioma using the GEO database (GEO series GSE16581) and quantitative-PCR (qPCR).

Results: Lectin cytochemistry revealed that the terminal galactose (Gal) and N-acetyl galactosamine (GalNAc) were highly expressed in primary benign meningioma cells (WHO grade I) compared to malignant meningioma cell lines (WHO grade III). The expression profile of mucin types O-glycosyltransferases in meningiomas were observed through the GEO database and gene expression experiment in meningioma cell lines. In the GEO database, C1GALT1-specific chaperone (COSMC) and mucin 1 (MUC1) were significantly increased in malignant meningiomas (Grade II and III) compared with benign meningiomas (Grade I). Meanwhile, in the cell lines, Core 2 β1,6-N-acetylglucosaminyltransferase-2 (C2GNT2) was highly expressed in malignant meningiomas. We then investigated the complex mucin-type O-glycans structures by determination of sialyltransferases and fucosyltransferases. We found ST3 β-galactoside α-2,3-sialyltransferase 4 (ST3GAL4) was significantly decreased in the GEO database, while ST3GAL1, ST3GAL3, α1,3 fucosyltransferases 1 and 8 (FUT1 and FUT8) were highly expressed in malignant meningioma cell lines-(HKBMM)-compared to primary benign meningioma cells-(SUT-MG12 and SUT-MG14).

Conclusion: Our findings are the first to demonstrate the potential glycosylation changes in the O-linked glycans of malignant meningiomas compared with benign meningiomas, which may play an essential role in the progression, tumorigenesis, and malignancy of meningiomas.

Keywords: Fucosyltransferases; Glycosyltransferases; Meningiomas; Mucin; O-linked glycosylation; Sialyltransferases.

Figure 1. Characterization of primary benign meningioma cells.

Cell morphology by hematoxylin and eosin staining (H&E). Immunocytochemistry of somatostatin receptor 2A (SSTR2A), mucin and vimentin in primary benign and malignant meningiomas cells. (Magnification, 200×).

Figure 2. Lectin cytochemistry in primary benign and malignant meningiomas.

Lectins for mannose (ConA), fucose (UEA I), and N-acetyl galactosamine (DBA, VVL, RCA₁₂₀, SBA), (Magnification, 200×).

Figure 3. Lectin cytochemistry in primary benign and malignant meningiomas.

Lectins for N-acetyl glucosamine (WGA, GSL-II, DSL, LEL, STL), (Magnification, 200×).

Figure 4. Lectin cytochemistry in primary benign and malignant meningiomas.

Lectins for galactose (PNA, ECL, Jacalin) and sialic acid (MAL II, SNA), (Magnification, 200×).

Figure 5. Mucin-type O-linked Glycosyltransferases expressions in benign and malignant meningiomas.

(A) The mRNA expression levels of Mucin-type O-linked glycosyltransferases in meningioma were obtained from the GEO database (GEO series GSE16581) and *P < 0.05 vs WHO Grade I. (B) The relative mRNA expression of mucin-type O-linked glycosyltransferases were determined using qPCR. Expression values were presented as mean + SEM of three independent experiments.

Figure 6. Membrane-bound mucin expressions in benign and malignant meningiomas.

(A) The mRNA expression levels of membrane-bound MUCINs in meningioma were obtained from the GEO database (GEO series GSE16581) and *P < 0.05 vs WHO grade I. (B) The relative mRNA expression of membrane-bound MUCINs were determined using qPCR. Expression values were presented as mean + SEM of three independent experiments.

Figure 7. Sialyltransferase (STs) expressions in benign and malignant meningiomas.

(A) The mRNA expression levels of sialyltransferase in meningioma were obtained from the GEO database (GEO series GSE16581) and *P < 0.05 vs WHO Grade I. (B) The relative mRNA expression of sialyltransferase were determined using qPCR. Expression values were presented as mean + SEM of three independent experiments.

Figure 8. Fucosyltransferase (FUTs) expressions in benign and malignant meningiomas.

(A) The mRNA expression levels of fucosyltransferase in meningioma were obtained from the GEO database (GEO series GSE16581). (B and C) The relative mRNA expression of fucosyltransferase were determined using qPCR. Expression values were presented as mean + SEM of three independent experiments.

Figure 9. Proposed structures of the mucin type O-linked glycosylation in malignant meningiomas (WHO grade III).

High expression of C1GALT1, COSMC, C2GNT2, ST3GAL1, ST3GAL3, FUT1, FUT2, FUT3, FUT6, FUT7, and FUT8 were demonstrated in malignant meningiomas.