Estrogen induces secretary proteins in transformed mouse Leydig cell in vivo, but not in vitro

The estrogen-induced proteins were analyzed in one of estrogen responsive mouse Leydig tumors. The incubation of cells freshly prepared from solid tumors with [35S] methionine resulted in the demonstration of estrogen-induced secretary protein with a molecular weight of 34,000. The additional minor estrogen-induced secretary protein (36,000) was also identified. An exposure of these cells to the culture condition for 48 hr caused the loss of their ability to synthesize these secretary proteins even in the presence of estrogen. In contrast, minced tumor tissue was observed to sustain the ability to synthesize these proteins at least for 48 hr. These results would suggest that some cellular arrangement is required for the synthesis of estrogen-induced proteins.