Growth and differentiation of teratocarcinoma OTT6050 affected by host hormonal changes in old mice.

We previously reported the age and sex dependent decrease in the growth rate of teratocarcinoma OTT6050. Studies of the effects of hormones on the tumor growth are presented here. Age related changes in the serum levels of triiodothyronine, thyroxine, progesterone, testosterone and estradiol that increase in the young adult and decrease in the old were observed with radioimmunoassay. Administration of estradiol to tumor-bearing, 50 week-old female mice increased the tumor growth rate to that of 10 week-old mice. Tumor growth rates in estradiol-treated 10 week-old female and male mice were slightly accelerated compared to the control, but not as fast as that of control juveniles. It can be concluded that extrinsic estradiol stimulates the teratocarcinoma growth in vivo especially in old female mice. Age-dependent decline of the growth rate of teratocarcinoma in the female is due partly to changes in estrogen level.