α2,6-hyposialylation of c-Met abolishes cell motility of ST6Gal-I-knockdown HCT116 cells

Abstract

Aim: We aimed to investigate the potential modification of previously unrecognized surface glycoprotein(s) by α2,6-sialylation other than by integrins. Methods: The expression of β-galactoside α2,6-sialyltransferase (ST6Gal-I) in the colon cancer cell line HCT116 was reduced by siRNA. The adhesion and Boyden chamber assay were used to detect the variation in cell motility. α2,6-Sialylation proteins were detected with lectin affinity assay. The mRNA expression, protein expression and downstream signaling modulation with siRNA were detected using reverse transcription-polymerase chain reaction, flow cytometry analysis, and Western blot. Results: In HCT116 cells, the knockdown of ST6Gal-I inhibited cell motility, but did not affect cell adhesion. This selectively altered cell migration was caused by the loss of α2,6-sialic acid structures on c-Met. Moreover, STAT3 was dephosphorylated at tyrosine 705 in ST6Gal-I-knockdown (ST6Gal-I-KD) HCT116 cells. Conclusion: c-Met is the substrate of ST6Gal-I. The hyposialylation of c-Met can abolish cell motility in ST6Gal-I-KD HCT116 cells.

NEU1 and NEU3 Sialidase Activity Expressed in Human Lung Microvascular Endothelia

“…EC migration requires responsiveness to multiple endogenous mediators, EC disengagement from adjacent ECs, and dynamic alternating adhesion/detachment from the underlying extracellular matrix (ECM) (52). Multiple sialoproteins known to participate in the EC migratory response are expressed both on the EC surface and within the underlying ECM (53)(54)(55)(56)(57)(58)(59). Potential NEU1 substrates might include the receptors for VEGFs, fibroblast growth factor (FGF), hepatocyte growth factor, insulin-like growth factor-1 (IGF-1), platelet-derived growth factor (PDGF), epidermal growth factor, angiopoietins, insulin growth factor, interleukins, tumor necrosis factor ␣, and platelet-activating factor (52).…”

“…Potential NEU1 substrates might include the receptors for VEGFs, fibroblast growth factor (FGF), hepatocyte growth factor, insulin-like growth factor-1 (IGF-1), platelet-derived growth factor (PDGF), epidermal growth factor, angiopoietins, insulin growth factor, interleukins, tumor necrosis factor ␣, and platelet-activating factor (52). In fact, desialylation of the receptor for hepatocyte growth factor, c-Met, expressed on HCT116 colonic cancer cells reportedly abolishes their motility (58). Two other growth factor receptors, VEGF and FGF receptors, each is regulated by gangliosides (53,60).…”

Nutrient-deprived cancer cells preferentially use sialic acid to maintain cell surface glycosylation

“…The activity of α2→3-sialyltransferase (α2→3-ST) and α2→6-sialyltransferase (α2→6-ST) to galactose was determined with a solid phase assay using asialofetuin-precoated plates as previously described [24]. Briefly, various cell lysates containing equal amount of protein were placed into the wells and CMP-Neu5Ac was then added to initiate the reaction.…”

Preferential Lectin Binding of Cancer Cells upon Sialic Acid Treatment Under Nutrient Deprivation

“…The activity of ST3Gal-I and ST6Gal-I was determined by solid phase assay using asialofetuin precoated plates as previously described (18). Briefly, various cell lysates containing equal amount of protein were taken into the wells and CMP-Neu5Ac was added to initiate the reaction.…”