Flow Cytometric Study of Site‐Directed Chemotherapy with Estradiol‐17β as a Drug Carrier to Human Endometrial Adenocarcinoma Cells in vitro

Abstract

The effects of Estracyt®, HN2 (nitrogen mustard) derivative of estradiol‐17β, and free HN2 on the cell kinetics of the estrogen receptor (ER) positive human endometrial cancer cell line HEC‐1, were investigated using flow cytometry. HN2 at 1 μg/ml showed a marked increase in the S phase and a decrease in the G0 + Gi phase. However, with equivalent doses of Estracyt® at 10 μg/ml, the accumulation in the G2 + M phase was even more marked. Synchronization in the S phase with methotrexate (MTX) showed no increase in sensitivity to these drugs. The above results suggest that the free HN2 has an effect regardless of the cell cycle phase, whereas the effects of Estracyt® may depend on a fixed population of target cells existing in the G0+G1, S and G2 + M phases. Synchronization in the G1 phase with sodium n‐butyrate could increase the target effects of Estracyt® in the S phase.