Effects of oestradiol and progesterone on the alkaline phosphatase activity of a human endometrial cancer cell-line

The alkaline phosphatase (ALPase) activity of a human endometrial caner cell-line, established and designated as HEC-50-B in our laboratory, was investigated biochemically and histochemically in relation to its cell growth pattern and to the effects of the sex steroid hormones, oestradiol and progesterone. The ALPase activity increased sharply in the early stationary phase to reach an activity almost 2.5 times higher than that obtained in earlier stages of the culture. On administration of oestradiol to the culture medium, a sharp elevation of the ALPase activity was induced on an average of 2 days earlier (late logarithmic phase) than in the case of an ordinary culture (no hormone administration), without causing a notable change in cell growth pattern. It should be noticed, however, that progesterone at such a low concentration that had very little effect on cell growth in the culture could clearly prohibit the elevation of ALPase activity. This hormonal effect on the ALPase activity resembled that on the enzyme activity of the endometrium of adult women. The ALPase activity of both the cultured endometrial cancer cells and the endometrium was found to be a sensitive indicator of the effect of progesterone. It would be a useful tool for future study in elucidating the mechanism of hormonal control of the neoplasm.