A fibroblastic (MMC-F) and an epithelial (MMC-E) cell line were established from a single embryo of the wild mouse strain Mus musculus castaneous. Clonal derivatives of these lines have been grown for four years in culture without any significant morphological changes after establishment. The cell lines do not express antigens related to known mouse type C viruses and are resistant to activation by bromodeoxyuridine. We have classified the MMC-E cell line (clone 7) as epithelial by the following criteria: (a) morphological appearance; (b) low levels of extracellular fibronectin; (c) the demonstration of tight junctions and desmosomes at high resolution; and (d) production of poorly differentiated carcinomas when inoculated in nude mice.

MMC-F and MMC-E cells form flat monolayers in plastic dishes and do not grow in soft agar; tests for tumorigenicity of cells at all passages were negative. Both cell lines are susceptible to chemical as well as type C viral transformation in vitro. Inoculation of transformed MMC-F cells into nude mice gave rise to fibrosarcomas, whereas transformed MMC-E cells produced poorly differentiated carcinomas. The availability of a set of stable, nontransformed syngeneic mouse cell lines which differ in their phenotype should prove useful for studies on the mechanisms of malignant transformation. The epithelial cell line, MMC-E, in particular, should be helpful in the study of chemical as well as viral carcinogenesis in view of the fact that the majority of human tumors are of epithelial origin, and an appropriate epithelial cell culture system has thus far not been available.


This study was supported by the Virus Cancer Program of the NIH.

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