Ledda F, Bravo A I, Adris S, Bover L, Mordoh J, Podhajcer O L
Institute of Biochemical Investigation Luis F. Leloir, Campomar Foundation and Faculty of Exact and Natural Sciences, University of Buenos Aires, Argentina.
J Invest Dermatol. 1997 Feb;108(2):210-4. doi: 10.1111/1523-1747.ep12334263.
SPARC (secreted protein acidic and rich in cysteine) is an extracellular protein associated with tissues exhibiting high rates of cell proliferation and matrix remodeling. The current work shows that the human melanoma cell lines IIB-MEL-LES, IIB-MEL-IAN, and IIB-MEL-J and different human metastatic melanomas expressed high levels of SPARC mRNA and protein. By western blot analysis we detected a single secreted 42-kDa band in human diploid fibroblasts-conditioned medium and a 45- to 40-kDa doublet in the three melanoma cell lines and all the metastatic melanomas tested. Part of the melanoma samples and cell lines showed an additional doublet of 36-34 kDa. SPARC mRNA was expressed by the three established cell lines, 14 metastatic melanoma samples, and tumors raised in nude mice, and no spliced variants were found. The heterogeneous pattern of SPARC secreted by human melanoma cells is the result of post-translational glycosylation and a specific extracellular leupeptin-inhibitable cleavage. Unlike human fibroblasts, melanoma cells did not overexpress SPARC on addition of TGF-beta. Immunohistochemical analysis showed that SPARC was strongly expressed in 100% of primary melanomas (7 of 7) and metastatic melanomas (29 of 29), moderately expressed in most of the positive dysplastic nevi (13 of 14), and only weakly expressed in nevocellular nevi (4 of 25). Normal melanocytes did not express SPARC. The data suggest that the expression of SPARC is associated with the neoplastic progression of human melanoma.
SPARC（分泌性酸性富含半胱氨酸蛋白）是一种细胞外蛋白，与细胞增殖率高和基质重塑的组织相关。目前的研究表明，人黑色素瘤细胞系IIB - MEL - LES、IIB - MEL - IAN和IIB - MEL - J以及不同的人转移性黑色素瘤表达高水平的SPARC mRNA和蛋白。通过蛋白质印迹分析，我们在人二倍体成纤维细胞条件培养基中检测到一条单一的42 kDa分泌条带，在三种黑色素瘤细胞系和所有测试的转移性黑色素瘤中检测到45至40 kDa的双条带。部分黑色素瘤样本和细胞系显示出另外一条36 - 34 kDa的双条带。SPARC mRNA由三种已建立的细胞系、14个转移性黑色素瘤样本以及裸鼠体内生长的肿瘤表达，未发现剪接变体。人黑色素瘤细胞分泌的SPARC的异质性模式是翻译后糖基化和一种特定的细胞外亮抑酶肽可抑制的切割的结果。与人类成纤维细胞不同，黑色素瘤细胞在添加转化生长因子-β后不会过度表达SPARC。免疫组织化学分析表明，SPARC在100%的原发性黑色素瘤（7例中的7例）和转移性黑色素瘤（29例中的29例）中强烈表达，在大多数阳性发育异常痣（14例中的13例）中中度表达，而在细胞痣（25例中的4例）中仅弱表达。正常黑色素细胞不表达SPARC。数据表明，SPARC的表达与人类黑色素瘤的肿瘤进展相关。
