The effect of β-d-xylosides on the proliferation and proteoglycan biosynthesis of monoblastic U-937 cells

Abstract

The monoblastic cell line U-937 was cultured in the presence of C-ethyl beta-D-xyloside (E-xyl), hexyl beta-D-thioxyloside (HX-xyl), p-nitrophenyl beta-D-xyloside, phenyl beta-D-xyloside or phenyl alpha-D-xyloside. All of the beta-D-xylosides inhibited proliferation, but HX-xyl was by far the most efficient, and had a maximum effect at 1 mM concentration. The inhibitory effect of HX-xyl could be reversed; after washing, the HX-xyl-treated cells proliferated with a pattern similar to that of control cells. For more detailed analysis of the effects of beta-D-xylosides on cell proliferation and chondroitin sulphate (CS)/chondroitin sulphate proteoglycan (CSPG) structure, a comparison between the effects of E-xyl and HX-xyl was made. Treating the cells with 1 mM-HX-xyl resulted in a large increase in CS synthesis, whereas 1 mM-E-xyl had only minor effects on the rate of PG/glycosaminoglycan synthesis. Sepharose CL-6B gel chromatography of medium and cell fractions from 35S-labelled cells revealed that HX-xyl treatment resulted in the expression of only free CS chains, whereas E-xyl exposure leads to the synthesis of both large and small CSPGs, as well as some free CS chains. The expression of elevated levels of free CS chains was clearly correlated to the inhibition of proliferation. The proliferation of U-937-4, a clone of U-937 synthesizing ten times more CSPG/CS than the parent line, was equally inhibited by HX-xyl treatment. With this clone, however, there was no stimulation of CS synthesis after xyloside exposure, indicating that the elevated level of CS evident after xyloside treatment of the parent cell line is not causing the inhibition of proliferation. Furthermore, the biosynthesis of hyaluronate was shown not to be implicated in the xyloside-induced decrease in proliferation. The inhibition of proliferation observed in the presence of 1 mM-HX-xyl did not lead to differentiation of the cells into macrophage-like cells, as is observed when the cells are cultured in the presence of phorbol esters, agents also known to inhibit proliferation of U-937 cells.

Secretion of macrophage urokinase plasminogen activator is dependent on proteoglycans

“…Further, samples were analyzed both before and after treatment with alkali (NaOH), a treatment that is known to release glycosaminoglycans from their respective protein cores. In agreement with a previous study [14], treatment with HX-xyl resulted in a shift from synthesis of predominantly intact proteoglycans to an almost exclusive synthesis of free glycosaminoglycan chains (Fig. 1).…”

“…Hexyl-b-D-thioxyloside (HX-xyl) was used as described previously. This particular xyloside was shown to be one of the most efficient abrogators of proteoglycan biosynthesis in comparison with other xylosides [14,15]. Chondroitinase ABC (C-ABC, EC 4.2.2.4) was bought from Seikagaku Kogyo Co., Tokyo, Japan.…”

“…These compounds have been widely used to study proteoglycan biosynthesis and the role of proteoglycans in different biological processes. b-D-Xylosides will compete with endogenous core protein for access to the glycosaminoglycan biosynthesis machinery [14], resulting in the biosynthesis of free glycosaminoglycan chains attached to the b-Dxyloside rather than intact proteoglycans. Depending on the concentration of xylosides used, endogenous proteoglycan expression may be completely abrogated.…”

“…These compounds have been widely used to study proteoglycan biosynthesis and the role of proteoglycans in different biological processes. b-D-Xylosides will compete with endogenous core protein for access to the glycosaminoglycan biosynthesis machinery [14], resulting in the biosynthesis …”

Synthesis and biology of oligoethylene glycol linked naphthoxylosides

“…For instance, they have been shown to exhibit (i) antiprion activities, 10 (ii) antithrombotic properties, [11][12] (iii) inhibiting effects on tumor invasion, (iv) beneficial effects on skin aging, [13][14] (v) enhancing spinal cord repair after injury, 15 (vi) antiangiogenesis effects, 16 and (vii) tumor selective antiproliferative activities [17][18][19] . Recently, we showed that 2-(6-hydroxynaphthyl) β-D-xylopyranoside, XylNapOH (1b, Figure 1), in contrast to 2-naphthyl β-D-xylopyranoside, XylNap (1a, Figure 1), selectively inhibited tumor growth both in vitro and in vivo.…”