Tumorigenicity of morphologically distinct transformed foci induced by 3-methylcholanthrene in BALB/c-3T3 cells.
Mutat Res 2000 Feb; 447(2):281-286
Studies have been performed in our laboratory to determine the preneoplastic and neoplastic potential of cells from morphologically different types of transformed foci. Transformed foci induced by 3-methylcholanthrene in BALB/c-3T3 cells were classified into five morphologically distinct types based on size (2-3, 3-4 and >4 mm in diameter), invasiveness (smooth vs. invading margins) and other properties (piling vs. spread). In our previous report, we showed that cells from all five types grew in soft agar, transformed normal NIH 3T3 cells and formed foci on normal layer of BALB/c-3T3 cells. In this study, the neoplastic/tumorigenic potential of cells from the five different types of transformed foci was investigated in nude mice. About two million cells from each transformed focus were injected into 4-week-old nude mice. Non-transformed BALB/c-3T3 cells were used as control. The results of this study indicate that all the 45 athymic mice injected with different transformants developed tumors between 2 and 4 weeks after injection. Tumors were not observed in eight mice injected with non-transformed BALB/c-3T3 cells. All tumors were histopathologically confirmed fibrosarcomas. These findings indicate that all five morphologically different foci show tumorigenicity and that any foci of size > or =2 mm regardless of invasiveness and piling could be scored as positive during the cell transformation assay.
Tumors; Tumorigens; Tumorigenesis; Cell-transformation; Cell-morphology; Laboratory-testing; Laboratory-animals; Animals; Animal-studies
Toxicology and Molecular Biology Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, M/S 3014, 1095 Willowdale Road, Morgantown, WV 26505-2888, USA