期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2017
卷号：114
期号：46
页码：12237-12242
DOI：10.1073/pnas.1715236114
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：NIH 3T3 cells grown in conventional Dulbecco’s modification of Eagle’s basal medium (DME) produce no transformed foci when grown to confluence in 10% calf serum (CS). A few cultures were transformed by ras oncogenes when transfected with DNA from neoplastic cells, but they failed to do so in 80 to 90% of the transfections. However, when they were grown in a medium [molecular, cellular, and developmental biology 402 (MCDB 402)] optimized for their clonal growth in minimal serum, they produced transformed foci without transfection in 10% CS, but not in 2% CS. The first response to growth in MCDB 402 in 2% CS in successive rounds of contact inhibition was uniform increases in saturation density of the population. This was followed by the appearance of transformed foci. A systematic study was made of the dynamics of neoplastic progression in various concentrations of CS in a single round of confluence at 2 and 3 wk, followed by three sequential rounds of confluence in 2% CS for 2 wk. There was a linear relationship between CS concentration and saturation density in the first-round cultures and continuing differences in subsequent cultures. The hyperplastic field of normal-looking cells surrounding transformed foci became increasingly permissive for transformation with serial culture. The dynamics show that epigenetic selection is the major driving force of neoplastic development. Cells from dense foci produced malignant fibrosarcomas in mice, thereby exhibiting a positive relationship between transformation in culture and the development of tumors.
关键词：selection ; saturation density ; cellular microenvironment ; epigenetics
