Grisham J W, Smith J D, Tsao M S
Cancer Res. 1984 Jul;44(7):2831-4.
The ability of eukaryotic cells in culture to proliferate in calcium-poor medium has been found to characterize populations of transformed cells, but the relationship between this phenotypic property and tumorigenicity at the cellular level is unclear. Thus, we have isolated 14 clonal subpopulations, based on their ability to colonize in calcium-poor medium, from a parental tumorigenic rat hepatic epithelial cell line which was transformed by multiple exposures to N-methyl-N'-nitro-N-nitrosoguanidine. These clonal subpopulations of cells were tested for their ability to grow in soft agar, to express gamma-glutamyl transpeptidase activity, and to form tumors upon back-transplantation into isogeneic newborn rats. The results indicated that clonal subpopulations of cells selected by their ability to grow in calcium-poor medium were phenotypically heterogeneous for gamma-glutamyl transpeptidase activity and anchorage-independent growth, and, more importantly, they were not more tumorigenic than the phenotypically heterogeneous parental cell line. This observation suggests that the capability of cultured hepatic epithelial cells to grow in calcium-poor medium is not tightly coupled to the tumorigenic phenotype.
已发现培养的真核细胞在低钙培养基中增殖的能力是转化细胞群体的特征，但这种表型特性与细胞水平的致瘤性之间的关系尚不清楚。因此，我们从经多次暴露于N-甲基-N'-硝基-N-亚硝基胍转化的亲代致瘤大鼠肝上皮细胞系中，根据其在低钙培养基中定殖的能力分离出14个克隆亚群。测试了这些细胞克隆亚群在软琼脂中生长的能力、表达γ-谷氨酰转肽酶活性的能力以及回植到同基因新生大鼠体内形成肿瘤的能力。结果表明，根据其在低钙培养基中生长的能力选择的细胞克隆亚群在γ-谷氨酰转肽酶活性和不依赖贴壁生长方面表型异质性，更重要的是，它们的致瘤性并不比表型异质的亲代细胞系更强。这一观察结果表明，培养的肝上皮细胞在低钙培养基中生长的能力与致瘤表型并非紧密相关。
