Supplementary MaterialsSuplemental Information 41598_2018_25521_MOESM1_ESM
May 11, 2021
Supplementary MaterialsSuplemental Information 41598_2018_25521_MOESM1_ESM. immunocytostaining, particularly when stimulated with serum. Masking of GalNAc-DSLc4 with antibodies as well as PI3K inhibitor suppressed malignant properties of the transfectants. These Caspofungin Acetate results suggested that GalNAc-DSLc4 is usually involved Caspofungin Acetate in malignant properties of RCCs by forming a molecular complex with integrins in lipid rafts. Introduction Recently, a number of studies indicate that some aberrant glycosylation is a result of initial oncogenic transformation, playing a key role in the enhancement of invasion and metastasis. It has been reported that high expression of some glyco-epitopes promotes tumor invasion and metastasis, leading to 5C10 year shorter survival rates of patients, whereas expression of some other glyco-epitopes suppresses tumor progression, leading to longer postoperative survival terms1,2. Mechanisms for the expression of these novel glyco-epitopes via the activation of respective glycosyltransferase genes have been extensively studied. However, little is usually comprehended about mechanisms through which specific glyco-epitopes induce invasive and metastatic phenotypes of tumor cells. In the case of glycosphingolipids, disialyl glycosphingolipids such as GD3 and GD2 have been reported to be associated with malignant transformation, cancer invasion, metastasis and prognosis3C6. Interaction of these disialyl structures with members of a lectin family, siglecs (ssialic acid-binding, immunoglobulin-like lectins), might be considered to be involved in the survival of cancer cells7,8. On the other hand, we have analyzed the mechanism for the synthesis of disialyl ganglioside with -structure, and isolated cDNAs for the responsible synthetic enzymes, such as ST6GalNAc-V9 and ST6GalNAc-VI10. We have also decided that ST6GalNAc-VI is the sialyltransferase responsible for the synthesis of disialyl Lewis a (Lea), which contains a branched-type disialyl structure on a lacto-core structure11. Interestingly, in addition to disialyl galactosylgloboside (DSGG) identified as one of major disialyl gangliosides from renal cell carcinoma (RCC) tissues12, another RCC-specific disialyl ganglioside was found in TOS-1 cell line13. This disialyl ganglioside was characterized to have a novel hybrid structure between ganglio-series GM2 and a lacto-series type 1-core. The antigen is usually termed GalNAc-disialyl Lc4 Cer (IV4GalNAcIV3NeuAcIII6NeuAcLc4; abbreviated GalNAc-DSLc4). Among RCCs, TOS-1 cells were observed to most strongly adhere to lung tissue sections, then, GalNAc-DSLc4 was expected to be a marker indicating possible activity to promote distant metastasis of RCC. ST6GalNAc-VI was also expected to be Caspofungin Acetate involved in the synthesis of this novel disialyl ganglioside, GalNAc-DSLc4. In this study, we identified the responsible transferase for biosynthesis of GalNAc-DSLc4 in RCCs to investigate roles of GalNAc-DSLc4. Then, we established GalNAc-DSLc4-overexpressing transfectant cells from an RCC cell line VMRC-RCW by using cloned B4GalNAc-T2 cDNA14, and studied molecular mechanisms for GalNAc-DSLc4-mediated biosignals. We demonstrate here that signaling pathway such as PI3K/Akt undergoes stronger phosphorylation after serum treatment in GalNAc-DSLc4-expressing cells than in control cells, and that GalNAc-DSLc4 is involved in recruitment of integrin 1 into glycolipid-enriched microdomain (GEM)/rafts around the cell surface. GalNAc-DSLc4 actually cooperates with integrin 1 to enhance cell proliferation, invasion, and adhesion to laminin, leading to the increased malignant properties of RCCs. Results Typing of renal cancer cell lines Expression of globo-series and lacto-series glycosphingolipids in 20 renal cancer cell lines and normal HRPTE cells were analyzed by flow cytometry (Table?1). It Rabbit Polyclonal to RASA3 was revealed that high expression of monosialyl galactosylgloboside (MSGG) was detected in almost all RCC lines, whereas DSGG expression was minimal or none in the RCC lines as shown previously15. In turn, high expression levels of DSGG and low expression levels of MSGG were detected in the normal human renal proximal tubule epithelial cells. Thus, RCC lines generally showed high expression of globo-series glycolipids and low expression of lacto-series glycolipids. But increased expression of a rare lacto-series glycolipid GalNAc-DSLc4 was found in majority of RCC lines (Fig.?1A). Table 1 Expression pattern of renal cancer-related glycolipids. profiles mean RM2-stained cells and profiles mean unfavorable cells. (F) Reduction of GalNAc-DSLc4 expression by D-PDMP treatment (for 6 days, conc. at 50 M). profiles mean reduced RM2 cells in flow cytometric assay. Identification of B4GalNAc-T2 as a responsible enzyme for the synthesis of GalNAc-DSLc4 To identify the B4GalNAc-T responsible for the synthesis of GalNAc-DSLc4, Caspofungin Acetate we prepared expression vectors for 6 B4GalNAc-Ts and examined the enzyme.