Minard Meghan E, Herynk Matthew H, Collard John G, Gallick Gary E
Department of Cancer Biology, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Blvd, Box 173, Houston, TX 77030, USA.
Oncogene. 2005 Apr 7;24(15):2568-73. doi: 10.1038/sj.onc.1208503.
Alterations in migration and adhesion are critical to invasion and metastasis. To examine signaling pathways important for colon tumor metastasis, cells of increased migratory potential from the low migratory SW480 human colorectal carcinoma parental cell line were biologically selected by serial migration through modified Boyden chambers. Several sublines were obtained with statistically significantly increased migration relative to the parental cell line. One highly migratory population was single-cell cloned and characterized. The migratory clones exhibit a four- to five-fold increase in protein and mRNA expression of T-lymphoma invasion and metastasis gene 1 (Tiam1), a guanine nucleotide exchange factor. To determine directly the role of Tiam1 in the migration of these migratory sublines, the parental SW480 cell line was transfected with a plasmid encoding the Tiam1 protein, and single cell clones were established. Ectopic expression of Tiam1 in these clones led to morphologic changes identical to biologically selected clones and increased migration. Finally, the implantation of clones that overexpress Tiam1 into the cecum of athymic mice resulted in tumor growth in the spleen, liver, and lung, whereas parental cells do not form tumors by this route of injection. These results demonstrate that overexpression of Tiam1 contributes to the metastatic phenotype of colon cancer cells.
迁移和黏附的改变对于侵袭和转移至关重要。为了研究对结肠肿瘤转移重要的信号通路，通过改良的博伊登小室进行连续迁移，从低迁移性的SW480人结肠直肠癌亲本细胞系中生物学筛选出具有更高迁移潜力的细胞。相对于亲本细胞系，获得了几个迁移能力在统计学上显著增加的亚系。对一个高迁移性群体进行单细胞克隆并进行表征。迁移克隆显示T淋巴瘤侵袭和转移基因1（Tiam1，一种鸟嘌呤核苷酸交换因子）的蛋白质和mRNA表达增加了四到五倍。为了直接确定Tiam1在这些迁移亚系迁移中的作用，用编码Tiam1蛋白的质粒转染亲本SW480细胞系，并建立单细胞克隆。这些克隆中Tiam1的异位表达导致形态学变化与生物学筛选的克隆相同，并增加了迁移。最后，将过表达Tiam1的克隆植入无胸腺小鼠的盲肠，导致脾脏、肝脏和肺部出现肿瘤生长，而亲本细胞通过这种注射途径不会形成肿瘤。这些结果表明Tiam1的过表达有助于结肠癌细胞的转移表型。
