Wu X, Kan M, Wang F, Jin C, Yu C, McKeehan W L
Center for Cancer Biology and Nutrition, Institute of Biosciences and Technology, Texas A&M University System Health Science Center, Houston, Texas 77030-3303, USA.
Cancer Res. 2001 Jul 1;61(13):5295-302.
The abnormal appearance and age-dependent loss of resident fibroblast growth factor receptor-2 (FGFR2) and gain of activity of FGFR1 in epithelial cells is a hallmark of the slow progression to malignancy in some models of prostate cancer. Pericellular matrix heparan sulfate (HS) is an integral subunit of the FGFR tyrosine kinase complex that restricts activity in absence of FGF, facilitates binding of an activating FGF, and confers specificity for FGF isoforms. In this report, we isolated and purified HS proteoglycan (HSPG) from premalignant prostate tumor epithelial cells based on the ability of the HS chains to form a binary complex with immunoglobulin module II of the ectopic and progression-promoting FGFR1 that was competent to bind FGF. The FGFR1 affinity-purified product exhibited a specific activity of over 600 times that of crude cellular HSPG enriched from cell lysates by ion exchange chromatography. The purified preparation exhibited a single NH(2)-terminal sequence with 11 of 13 residues identical to syndecan-1. The activity of purified recombinant glutathione S-transferase-tagged syndecan-1 expressed in premalignant epithelial cells confirmed that syndecan-1 bears HS chains that exhibit the rare motif that forms the FGF-binding complex with ectopic FGFR1. These results are the first to identify by affinity purification a specific HSPG core protein, the HS chains of which act as an integral subunit of the FGFR complex. The results suggest that syndecan-1 provides HS chains in premalignant epithelial cells to both the FGFR2- and FGFR1-signaling complexes that are integral to their dual roles in progression to malignancy.
在某些前列腺癌模型中，常驻成纤维细胞生长因子受体2（FGFR2）出现异常表现且随年龄增长而丧失，上皮细胞中FGFR1活性增加，这是前列腺癌缓慢进展为恶性肿瘤的一个标志。细胞周围基质硫酸乙酰肝素（HS）是FGFR酪氨酸激酶复合物的一个组成亚基，在没有成纤维细胞生长因子（FGF）的情况下限制活性，促进激活型FGF的结合，并赋予FGF亚型特异性。在本报告中，我们基于HS链与异位且促进进展的FGFR1的免疫球蛋白模块II形成二元复合物并能够结合FGF的能力，从癌前前列腺肿瘤上皮细胞中分离并纯化了硫酸乙酰肝素蛋白聚糖（HSPG）。经FGFR1亲和纯化的产物的比活性比通过离子交换色谱从细胞裂解物中富集的粗制细胞HSPG高600多倍。纯化后的制剂显示出单一的NH(2)-末端序列，13个残基中有11个与syndecan-1相同。在癌前上皮细胞中表达的纯化重组谷胱甘肽S-转移酶标记的syndecan-1的活性证实，syndecan-1带有HS链，这些HS链呈现出与异位FGFR1形成FGF结合复合物的罕见基序。这些结果首次通过亲和纯化鉴定出一种特定的HSPG核心蛋白，其HS链作为FGFR复合物的一个组成亚基发挥作用。结果表明，syndecan-1在癌前上皮细胞中为FGFR2和FGFR1信号复合物提供HS链，这对于它们在进展为恶性肿瘤过程中的双重作用不可或缺。
