Clinical implication of fos and jun expressions and protein kinase activity in endometrial cancers.

Under the previous data of the presence of fos/jun expression via protein kinase C (PKC) activation by estrogen in endometrial cancer cell line (1), the following experiment was made on the endometrial cancer tissue of the human subject. The ratio of membrane/cytosol PKC activity and the level of fos/jun expression were significantly higher in well differentiated endometrial cancers than in those of moderately or poorly differentiated ones. Those two in the endometrial cancer were significantly higher than those in the normal counterpart. The ratio and the expression in normal uterine endometria of the proliferative phase were significantly higher than those in the secretory phase. Both in the endometria were significantly enhanced 1 week after the administration of estrogen. It is suggested that the linkage of fos/jun expression via PKC activation by estrogen might be exaggerated in the endometrial cancers, especially in the well differentiated, plausibly with the loss of the anti-estrogen effect of progesterone, but dedifferentiation might lose this linkage.