Immortalization and neoplastic transformation of normal rat colon epithelium: an in vitro model of colonic neoplastic progression.

BACKGROUND

Because of the refractory nature of colon epithelium to growth and maintenance in vitro, the cell lines currently available for study are derived from tumors. Unlike most epithelial model systems, there exist no preneoplastic, nontumorigenic colon cell lines for manipulation and study.

METHODS

Intact fetal rat colon was cultured in the presence of a feeder layer of cells producing a retrovirus that harbors the SV40 LT gene resulting in the establishment of immortalized colon cell lines.

RESULTS

The epithelial and intestinal origin of cell lines was established from the constitutive expression of keratin and villin, respectively. All cell lines displayed an absence of anchorage independent growth and failed to produce tumors in vivo. Neoplastic transformation of immortalized rat colon epithelial cell lines was achieved following introduction of individual oncogenic ras gene members or the v-src oncogene. Probing of cell lysates with phosphotyrosine antibodies revealed altered phosphotyrosyl protein profiles associated with different stages of colonic neoplastic progression.

CONCLUSIONS

The establishment of immortalized nontumorigenic colon epithelial cell lines facilitates the biochemical analysis of events associated with different stages of colonic neoplastic progression. In addition, this simple culture technique lends itself to studies involving alternative genetic elements implicated in the genesis of colon tumors.