AROMATASE-ACTIVITY AND THE EFFECT OF ESTRADIOL AND TESTOSTERONE ON DNA-SYNTHESIS IN ENDOMETRIAL CARCINOMA CELL-LINES

Human endometrial and breast carcinoma cell lines were examined for ar omatase activity and the effects of sex steroids (estradiol and testos terone) on DNA synthesis. Aromatase activity was high (greater than 50 0 fmol/10(7) cells/24 h) in the cell lines MCF-7 and OMC-2, moderate ( 100-499 fmol/10(7) cells/24 h) in the cell lines HEC-59 and Ishikawa, and low (less than 100 fmol/10(7) cells/24 h) in the HHUA cell line. A substantial stimulation of DNA synthesis by estradiol (10(-9) M) was observed in cell lines HEC-59, OMC-2, and MCF-7, with an increase in [ H-3]thymidine uptake of over 250%. The Ishikawa cell line was stimulat ed moderately (115-249%). No estradiol-induced increase in DNA synthes is was observed in HHUA. Responsiveness of DNA synthesis to testostero ne was observed in cell lines that showed the greatest response to est radiol, namely HEC-59, OMC-2, and MCF-7. Otherwise, estrogen-responsiv eness did not always correlate with a significant aromatase activity. These data suggest that some but not all endometrial carcinomas may po ssess an aromatase-dependent growth stimulating system.