Differences in the uptake and nuclear localization of anti‐proliferative heparan sulfate between human lung fibroblasts and human lung carcinoma cells

Abstract

Heparan sulfate inhibits the proliferation of normal human lung fibroblasts (HFL-1) but not of a human lung carcinoma cell-line (A549). In this study we investigated possible mechanisms and structural requirements by which antiproliferative heparan sulfates exerts its effects on binding, uptake and subcellular localisation. Both HFL-1 and A549 cells were incubated with 125I- or rhodamine-labeled L-iduronate-rich antiproliferative heparan sulfate species as well as L-iduronate-poor inactive ones. The antiproliferative heparan sulfate was bound to the cell surface on both HFL-1 and A549 cells, but to a lesser extent and with less affinity to A549 cells. Both cell types bound the antiproliferative heparan sulfate with one high- and with one low affinity site. The L-iduronate-poor heparan sulfate bound to a lesser extent and with less affinity to both cell types compared to the antiproliferative heparan sulfate. The antiproliferative heparan sulfate accumulated in the cytoplasm of HFL-1 cells after 24 h incubation, but after 72 h it was found evenly distributed in the nucleus. The time-scale for antiproliferative activity correlated with nuclear localization. In contrast, in A549 cells it was only found near the nuclear membrane. The inactive heparan sulfate was taken up in considerably smaller amounts compared to the antiproliferative heparan sulfate and could not be detected in the nucleus of either HFL-1 or A549 cells. Our data suggest that the antiproliferative activity of L-iduronate-rich heparan sulfate on normal fibroblasts may be due to direct effects on nuclear processes, such as gene transcription.

Nitric Oxide-dependent Processing of Heparan Sulfate in Recycling S-Nitrosylated Glypican-1 Takes Place in Caveolin-1-containing Endosomes

“…Previous studies have shown that exogenously supplied HS can be taken up by various cell types and be targeted to the nucleus (6,55,56). Uptake of another polyanion, hyaluronan, via non-clathrin-dependent endocytosis followed by lysosomal targeting has also been described (57).…”

“…No anMan-positive HS-oligosaccharides appeared to be targeted to the nucleus, which is thus in contrast to exogenously supplied HS. Usually, it is only a small fraction (Ͻ1%) of exogenously supplied HS that is taken up by cells and transported to the nucleus (56). However, both the rate of uptake and the amount of HS accumulating in the nuclei can be severalfold enhanced when HS is combined with a polyamine-lipid conjugate (6).…”

Antiproliferative heparan sulfate inhibiting hyaluronan and transforming growth factor-β expression in human lung fibroblast cells

“…Furthermore, annexin II has also been shown to bind both heparin and HS, thereby undergoing a larger conformational change when binding to heparin than HS (32). We have previously shown that HS6, but not HS2, is internalized and further translocated into the nucleus (24). Though the intracellular HSmediated effects are still under speculation, HS has the ability to affect transcription factors such as NF-B (33).…”

“…1B). This inhibitory effect of HS6 on cell proliferation has previously been shown to be independent of cytotoxic effects, measured as release of lactate dehydrogenase (LDH) (24). No change in cell growth was observed in cell cultures stimulated with HS2, suggesting that the fine structure of HS6 is involved in cell proliferation (17,20,21).…”

Proteoglycans in normal physiology and carcinogenesis

“…В свою очередь, степень сульфатирования ГС по 2-му положению опре-деляется присутствием в молекуле остатков L-идуро-новой кислоты (L-IdoUA). Показано, что экзогенные углеводные цепи ГС, обогащенные L-IdoUA, в отличие от ГС с низким содержанием L-IdoUA, накапливают-ся в цитоплазме нормальных фибробластов легкого (HFL-1), и временны е показатели их накопления кор-релируют с антипролиферативной активностью этих ГС [114]. В то же время углеводные цепи ГС не появ-ляются ни в цитоплазме, ни в ядрах клеток карциномы легкого (А549) через 24-72 ч инкубации этих клеток с экзогенными ГС.…”