Narita Keishi, Chien Jeremy, Mullany Sally A, Staub Julie, Qian Xiang, Lingle Wilma L, Shridhar Viji
Department of Laboratory Medicine and Experimental Pathology, Mayo Clinic Cancer Center, Rochester, MN 55905, USA.
J Biol Chem. 2007 May 11;282(19):14413-20. doi: 10.1074/jbc.M611395200. Epub 2007 Mar 15.
Heparan sulfate (HS) glycosaminoglycans are the oligosaccharide chains of heparan sulfate proteoglycans. The sulfation of HS glycosaminoglycan residues is required for its interaction with various heparin-binding growth factors to promote their biological activities to activate their high affinity receptor tyrosine kinases. We have identified HS glycosaminoglycan-6-O-endosulfatase HSulf-1 as a down-regulated gene in ovarian, breast, and several other cancer cell lines. Here we have shown that HSulf-1 inhibits autocrine activation of the EGFR-ERK (epidermal growth factor receptor-extracellular signal-regulated kinase) pathway induced by serum withdrawal in MDA-MB-468 breast cancer cells. Short hairpin RNA-mediated down-regulation of HSulf-1 in HSulf-1 clonal lines of MDA-MB-468 led to a significant increase in autocrine activation of ERK compared with vector only control. The autocrine signaling was also inhibited with neutralization antibodies against amphiregulin and HB-EGF, the heparin-binding growth factor family of the EGF superfamily. Furthermore, HSulf-1-mediated inhibition of autocrine signaling was associated with reduced cyclin D1 levels, leading to decreased S phase fraction and increased G(2)-M fraction, as well as increased cell death. Finally, evaluation of HSulf-1 expression levels in primary invasive breast tumors by RNA in situ hybridization indicated that HSulf-1 is down-regulated in the majority (60%) of tumors, with a predominant association with lobular histology. These data suggest a potential role of HSulf-1 down-regulation in mammary carcinogenesis.
硫酸乙酰肝素（HS）糖胺聚糖是硫酸乙酰肝素蛋白聚糖的寡糖链。HS糖胺聚糖残基的硫酸化是其与各种肝素结合生长因子相互作用以促进其生物活性从而激活其高亲和力受体酪氨酸激酶所必需的。我们已将HS糖胺聚糖-6-O-硫酸酯酶HSulf-1鉴定为卵巢癌、乳腺癌和其他几种癌细胞系中下调的基因。在此我们表明，HSulf-1抑制MDA-MB-468乳腺癌细胞中血清撤离诱导的表皮生长因子受体-细胞外信号调节激酶（EGFR-ERK）途径的自分泌激活。与仅载体对照相比，短发夹RNA介导的MDA-MB-468的HSulf-1克隆系中HSulf-1的下调导致ERK自分泌激活显著增加。抗双调蛋白和HB-EGF（表皮生长因子超家族的肝素结合生长因子家族）的中和抗体也抑制了自分泌信号传导。此外，HSulf-1介导的自分泌信号抑制与细胞周期蛋白D1水平降低相关，导致S期分数降低和G(2)-M期分数增加，以及细胞死亡增加。最后，通过RNA原位杂交评估原发性浸润性乳腺癌中HSulf-1的表达水平表明，HSulf-1在大多数（60%）肿瘤中下调，主要与小叶组织学相关。这些数据表明HSulf-1下调在乳腺癌发生中可能起作用。
