Department of Pathology, Integrative Oncological Pathology, Nippon Medical School, Tokyo, Japan.
Exp Mol Pathol. 2010 Jun;88(3):363-70. doi: 10.1016/j.yexmp.2010.01.010. Epub 2010 Feb 4.
Lumican is a member of a small leucine-rich proteoglycan (SLRP) family and it regulates the assembly and diameter of collagen fibers in the extracellular matrix of various tissues. Lumican expression was reported in various kinds of tumor cells. Lumican inhibits the growth of melanoma cells, but the lumican in pancreatic cancer correlated with an advanced stage and retroperitoneal and duodenal invasion. In this study, we clarified whether the enhanced expression of lumican contributes to cellular attachment, growth, colony formation, migration and invasion. HEK 293 cell, stably transfected with lumican cDNA synthesized and secreted a 50 kDa lumican protein at high levels in culture medium. The cells showed a polygonal appearance with long projections and the degree of adhesion of the cells to fibronectin was lower than that of empty vector transfected control cells (mock cells). In contrast, the degree of adhesion of the cells to type I collagen was not different from that of mock cells. The expression levels of alpha5 integrin, the major integrin subunit for fibronectin, were lower in lumican-transfected HEK cells than in mock cells. Furthermore, lumican-transfected HEK cells showed reduced growth rates in vitro and did not form colonies in soft agar. Phosphorylation of AKT, extracellular signal-regulated kinase (ERK) 1/2 and mammalian target of rapamycin (mTOR) decreased in the lumican-transfected HEK cells. Cell migration and invasion were not altered in lumican-transfected HEK cells and mock cells. These findings indicate that the 50kDa lumican protein plays important roles in the inhibition of HEK cell attachment and growth, and it might inhibit the activation of integrin pathways.
赖氨酰聚糖蛋白是小富含亮氨酸的蛋白聚糖 (SLRP) 家族的一员，它调节各种组织细胞外基质中胶原纤维的组装和直径。赖氨酰聚糖蛋白在各种肿瘤细胞中表达。赖氨酰聚糖蛋白抑制黑色素瘤细胞的生长，但胰腺癌中的赖氨酰聚糖蛋白与晚期及腹膜后和十二指肠侵犯有关。在这项研究中，我们阐明了赖氨酰聚糖蛋白的增强表达是否有助于细胞附着、生长、集落形成、迁移和侵袭。用合成的 cDNA 稳定转染 HEK 293 细胞并在培养基中高水平分泌 50kDa 的赖氨酰聚糖蛋白。细胞呈多边形，有长突起，与纤维连接蛋白的黏附程度低于空载体转染的对照细胞（mock 细胞）。相比之下，细胞与 I 型胶原的黏附程度与 mock 细胞没有不同。赖氨酰聚糖蛋白转染的 HEK 细胞中纤维连接蛋白的主要整合素亚基 α5 整合素的表达水平低于 mock 细胞。此外，赖氨酰聚糖蛋白转染的 HEK 细胞在体外生长速度较慢，在软琼脂中不形成集落。赖氨酰聚糖蛋白转染的 HEK 细胞中 AKT、细胞外信号调节激酶 (ERK) 1/2 和哺乳动物雷帕霉素靶蛋白 (mTOR) 的磷酸化减少。赖氨酰聚糖蛋白转染的 HEK 细胞和 mock 细胞的细胞迁移和侵袭没有改变。这些发现表明，50kDa 的赖氨酰聚糖蛋白在抑制 HEK 细胞附着和生长中发挥重要作用，并且可能抑制整合素途径的激活。
