Sugiyama K, Otori K, Esumi H
Investigative Treatment Division, National Cancer Center Research Institute East, Kashiwa, Chiba.
Jpn J Cancer Res. 1998 Jun;89(6):615-25. doi: 10.1111/j.1349-7006.1998.tb03263.x.
Somatic mutations of the K-ras oncogene play an important role in colorectal carcinogenesis. We determined whether rat colon epithelial cells could be transformed by introducing retroviruses carrying the activated human K-ras oncogene alone. Primary epithelial cells from the rat distal colon were infected with retroviruses carrying wild-type and two types of activated K-ras (asp and val at codon 12) cDNAs. Cells infected with the wild-type K-ras virus showed no change in morphology and died within 3 weeks, whereas the activated K-ras virus-infected cells underwent morphological changes within 3 days and continued to proliferate. From these cells, several cell lines were subsequently established. Epithelial cells transformed by activated K-ras formed colonies in soft agar culture and tumors in athymic nude mice. Multiple copies of human K-ras genes and large amounts of K-ras mRNAs and proteins were found in the transformed cells. These data suggest that overexpression of activated K-ras transforms rat colon epithelial cells.
K-ras癌基因的体细胞突变在结直肠癌发生过程中起重要作用。我们研究了仅通过导入携带激活型人K-ras癌基因的逆转录病毒，大鼠结肠上皮细胞是否能够被转化。用携带野生型和两种激活型K-ras（密码子12处为asp和val）cDNA的逆转录病毒感染大鼠远端结肠的原代上皮细胞。感染野生型K-ras病毒的细胞形态无变化，在3周内死亡，而感染激活型K-ras病毒的细胞在3天内发生形态变化并持续增殖。随后从这些细胞中建立了多个细胞系。激活型K-ras转化的上皮细胞在软琼脂培养中形成集落，在无胸腺裸鼠中形成肿瘤。在转化细胞中发现了多拷贝的人K-ras基因以及大量的K-ras mRNA和蛋白质。这些数据表明激活型K-ras的过表达可转化大鼠结肠上皮细胞。
