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Abstract Background β-1,3-Galactosyltransferase-4 (B3GALT4), a member of the β-1,3-galactosyltransferase gene family, is essential to the development of many malignancies. However, its biological function in breast cancer is still unknown. Method Publically accessible datasets, as well as quantitative real-time PCR, western blot, and immunohistochemistry on our patient cohort were used to investigate the expression levels of B3GALT4 in breast cancer. The correlation of B3GALT4 expression with clinical histopathological data and mortality in breast cancer patients was investigated. The effects of B3GALT4 in breast cancer in vitro and in vivo were investigated. RNA-seq, western blot, autophagolysosomes, and the fluorescence intensity of LC3 were used to explore the effects of B3GALT4 on autophagy. Western blot and gene set enrichment analysis (GSEA) were used to identify the AKT/mTOR pathway. Results B3GALT4 was significantly overexpressed in breast cancer tissues and was positively correlated with some aspects of clinicopathological status and poor prognosis. B3GALT4 overexpression significantly promoted cell proliferation, migration, and invasion, both in vitro and in vivo. B3GALT4 inhibition suppressed breast cancer cell proliferation, migration, and invasion in vitro. Suppression of B3GALT4 triggered autophagy and hindered the AKT/mTOR signaling pathway. Conclusion According to the present research, B3GALT4 blocked autophagy via the AKT/mTOR pathway and accelerated the growth of breast cancer. B3GALT4 may be an effective target for patients with breast cancer.

Background: β-1,3-Galactosyltransferase-4 (B3GALT4), a member of the β-1,3-galactosyltransferase gene family, is essential to the development of many malignancies. However, its biological function in breast cancer is still unknown. Method: Publically accessible datasets, as well as quantitative real-time PCR, western blot, and immunohistochemistry on our patient cohort were used to investigate the expression levels of B3GALT4 in breast cancer. The correlation of B3GALT4 expression with clinical histopathological data and mortality in breast cancer patients was investigated. The effects of B3GALT4 in breast cancer in vitro and in vivo were investigated. RNA-seq, western blot, autophagolysosomes, and the fluorescence intensity of LC3 were used to explore the effects of B3GALT4 on autophagy. Western blot and gene set enrichment analysis (GSEA) were used to identify the AKT/mTOR pathway. Results: B3GALT4 was significantly overexpressed in breast cancer tissues and was positively correlated with some aspects of clinicopathological status and poor prognosis. B3GALT4 overexpression significantly promoted cell proliferation, migration, and invasion, both in vitro and in vivo. B3GALT4 inhibition suppressed breast cancer cell proliferation, migration, and invasion in vitro. Suppression of B3GALT4 triggered autophagy and hindered the AKT/mTOR signaling pathway. Conclusion: According to the present research, B3GALT4 blocked autophagy via the AKT/mTOR pathway and accelerated the growth of breast cancer. B3GALT4 may be an effective target for patients with breast cancer. [ABSTRACT FROM AUTHOR]

Small extracellular vesicles (sEVs) are a type of membrane structure secreted by cells, which are involved in physiological and pathological processes by participating in intercellular communication. Glycosphingolipids (GSLs) are enriched in sEV and can be delivered to recipient cells. In this study, we found that overexpression of B3GALT4, the glycosyltransferase responsible for ganglioside GM1 synthesis, can induce the epithelial–mesenchymal transition (EMT) process in MCF-10A cells. Moreover, GM1 was verified to be presented on sEV from breast cancer cells. Overexpression of B3GALT4 resulted in elevated vesicular GM1 levels and increased sEV secretion in breast cancer cells. Proteomic analysis revealed that eleven sEV secretion-related proteins were differentially expressed, which might contribute to the altered sEV secretion. Of the identified proteins, 15 oncogenic differentially expressed proteins were documented to be presented in sEV. With the treatment of GM1-enriched sEV from breast cancer cells, the EMT process was induced in recipient non-tumorigenic epithelial MCF-10A cells. Our findings demonstrated that GM1-enriched sEVs derived from breast cancer cells induced the EMT process of recipient cells, which might provide essential information on the biological function of vesicular GM1. [ABSTRACT FROM AUTHOR]

Small extracellular vesicles (sEVs) are a type of membrane structure secreted by cells, which are involved in physiological and pathological processes by participating in intercellular communication. Glycosphingolipids (GSLs) are enriched in sEV and can be delivered to recipient cells. In this study, we found that overexpression of B3GALT4, the glycosyltransferase responsible for ganglioside GM1 synthesis, can induce the epithelial–mesenchymal transition (EMT) process in MCF-10A cells. Moreover, GM1 was verified to be presented on sEV from breast cancer cells. Overexpression of B3GALT4 resulted in elevated vesicular GM1 levels and increased sEV secretion in breast cancer cells. Proteomic analysis revealed that eleven sEV secretion-related proteins were differentially expressed, which might contribute to the altered sEV secretion. Of the identified proteins, 15 oncogenic differentially expressed proteins were documented to be presented in sEV. With the treatment of GM1-enriched sEV from breast cancer cells, the EMT process was induced in recipient non-tumorigenic epithelial MCF-10A cells. Our findings demonstrated that GM1-enriched sEVs derived from breast cancer cells induced the EMT process of recipient cells, which might provide essential information on the biological function of vesicular GM1.

Abstract Reduced levels of brain gangliosides GD1a, GD1b, GT1b and to a lesser extent GM1 have been found in substantia nigra (SN) from Parkinson's disease (PD) patients, along with decreased gene expression for key enzymes (B3Galt4, St3gal2) involved in synthesis of these gangliosides. Based on these observations, the present study examined the extent to which decreased expression of B3GALT4 mRNA and resulting decreased levels of GM1 ganglioside in dopaminergic cells may increase the vulnerability of these cells to degeneration in response to a neurotoxicant exposure that under normal circumstances would not result in neurodegeneration. Differentiated SK-N-SH cells were treated with B3GALT4 siRNA to significantly reduce B3GALT4 mRNA expression and decrease GM1 levels. Exposure of these cells to a low concentration (10 μM) of the neurotoxin MPP+ that previously produced no toxicity resulted in approximately 50% cell loss after B3GALT4 siRNA treatment. This was a similar a degree of cell loss observed with 100 μM MPP+ in normal, differentiated SK-N-SH cells. Addition of GM1 to the culture medium after siRNA treatment was able to significantly protect cells from enhanced MPP+ toxicity. These data suggest that decreased B3GALT4 and GM1 expression can increase cell vulnerability to potentially toxic stressors and that such mechanisms may contribute to dopaminergic neurodegeneration in PD. Highlights • B3GALT4 siRNA significantly reduced B3GALT4 mRNA expression. • B3GALT4 siRNA significantly decreased GM1 levels. • B3GALT4 siRNA enhanced toxic response to low level MPP+. • Decreased B3GALT4 and GM1 expression increases cell vulnerability to toxic stressors. [ABSTRACT FROM AUTHOR]

Determines whether the &beta-1,3-galactosyltransferase-4 (B3GALT4) gene is located within the major histocompatibility complex (MHC). Identification of B3GALT4 by direct sequencing of the amplified products and by Southern blot analysis employing the same amplicon as a probe; Findings on the presence of the B3GALT4 in the 453 bp telomeric to BING4 and 691 bp centrometic to ribosomal protein S18; Illustration of the genetic irder which agrees almost perfectly with the synthetic mouse segment around the H2-K gene.