Choi P M, Tchou-Wong K M, Weinstein I B
Comprehensive Cancer Center, College of Physicians and Surgeons, Columbia University, New York, New York 10032.
Mol Cell Biol. 1990 Sep;10(9):4650-7. doi: 10.1128/mcb.10.9.4650-4657.1990.
By using a retrovirus-derived vector system, we generated derivatives of the human colon cancer cell line HT29 that stably overexpress a full-length cDNA encoding the beta 1 isoform of rat protein kinase C (PKC). Two of these cell lines, PKC6 and PKC7, displayed an 11- to 15-fold increase in PKC activity when compared with the C1 control cell line that carries the vector lacking the PKC cDNA insert. Both of the overexpresser cell lines exhibited striking alterations in morphology when exposed to the tumor promoter 12-O-tetradecanoyl-phorbol-13-acetate (TPA). Following exposure to TPA, PKC6 and PKC7 cells displayed increased doubling time, decreased saturation density, and loss of anchorage-independent growth in soft agar; but these effects were not seen with the C1 cells. Also, in contrast to the control cells, the PKC-overproducing cells failed to display evidence of differentiation, as measured by alkaline phosphatase activity, when exposed to sodium butyrate. In addition, the PKC-overexpresser cells displayed decreased tumorigenicity in nude mice, even in the absence of treatment with TPA. These results provide the first direct evidence that PKC can inhibit tumor cell growth. Thus, in some tumors, PKC might act as a growth-suppressor gene.
通过使用逆转录病毒衍生载体系统，我们构建了人结肠癌细胞系HT29的衍生物，这些衍生物稳定地过表达编码大鼠蛋白激酶C（PKC）β1同工型的全长cDNA。与携带不含PKC cDNA插入片段的载体的C1对照细胞系相比，其中两个细胞系PKC6和PKC7的PKC活性增加了11至15倍。当暴露于肿瘤启动子12 - O - 十四烷酰佛波醇 - 13 - 乙酸酯（TPA）时，两个过表达细胞系的形态均出现显著改变。暴露于TPA后，PKC6和PKC7细胞的倍增时间增加，饱和密度降低，在软琼脂中丧失非锚定依赖性生长能力；但C1细胞未出现这些效应。此外，与对照细胞相比，当暴露于丁酸钠时，过表达PKC的细胞未能表现出通过碱性磷酸酶活性测定的分化迹象。另外，即使在未用TPA处理的情况下，过表达PKC的细胞在裸鼠中的致瘤性也降低。这些结果提供了PKC可抑制肿瘤细胞生长的首个直接证据。因此，在某些肿瘤中，PKC可能作为一种生长抑制基因发挥作用。
