HA-RAS ONCOGENE MUTATIONS IN CELL-LINES DERIVED FROM RAT TRACHEAL IMPLANTS EXPOSED INVIVO TO 7,12-DIMETHYLBENZ[A]ANTHRACENE

The frequency of Ha‐ras mutations was determined as a function of neoplastic progression in cell lines derived from rat tracheal implants exposed in vivo to 7,12‐dimethylbenz[a]anthracene. Restriction fragment‐length polymorphism (RFLP) analysis revealed an A → T transversion in the second base of codon 61 in 2 of 11 cell lines. One of the positive cell lines was tumorigenic, but the other was neither tumorigenic nor anchorage independent, thus indicating a lack of correlation between neoplastic stage and ras mutation. Densitometry analysis of the RFLP bands indicated that approximately 50% of the cells within these two heterogeneous populations contained the mutation. Direct sequence analysis of polymerase chain reaction—amplified DNA confirmed these results and did not reveal any other mutations in this region of the Ha‐ras gene. Copyright © 1990 Wiley‐Liss, Inc., A Wiley Company