Appearance of Malignant Phenotype with Partial Loss of Hormone Dependency in Androgen‐dependent Shionogi Carcinoma 115 Transfected with hst‐1 Gene

Shionogi Carcinoma 115 (SC 115) and Chiba Subline 2 (CS 2) are an androgen‐dependent mouse tumor and an androgen‐independent subline derived from SC 115, respectively. Since new expression of the transforming oncogene hst‐1 might be related with autonomous progression in CS 2, the present study was designed to examine the influence of expression of hst‐1 gene on SC 115. The transfectants of SC 115 with hst‐1 still retained androgen sensitivity of growth, although the cells could grow without androgen. The transfectants, however, developed fibroblast‐like appearance in the absence of androgen, in contrast to SC 115, which showed epithelial‐like appearance after deprivation of androgen. The transfectants acquired an ability to form colonies in soft agar in the absence of androgen. SC 115 could not form tumors in intact mice, but the transfectants formed tumors at a high rate in male mice but not in female ones. From these results, it was concluded that expression of hst‐1 was able to alter the phenotype of the androgen‐dependent tumor with partial loss of androgen‐dependency, and these changes might be advantageous for malignant progression.