Objective: To evaluate the action of all trans retinoic acid on human endometrial adenocarcinoma cell line RL95 -2. Methods ; The human endometrial adenocarcinoma cells ( RL95 - 2) cultured in vitro were treated with various concentrations of all trans retinoic acid( ATRA). At specific time points after treatment with ATRA

the effect of ATRA on the proliferation of RL95 -2 cells was determined by MTT method

and Cyclin A was detected by immunohistochemistry. The morphological change of RL95 -2 cells was observed by scanning electron microscope and transmission electron microscope. Results: A time - dependent and dose - dependent proliferation inhibition was demonstrated in RL95 -2

and ATRA induced a G0/G1 cell cycle arrest. The malignant morphological characteristic of RL95 -2 cells disappeared after treatment by ATRA. ATRA could down - regulate the expression of Cyclin A. Conclusion; The proliferation inhibition effect of ATRA on RL95 -2 cells cultured in vitro appears to be due to the down - regulation of Cyclin A. The results provide evidence for the potential effect of ATRA in the prevention and treatment of human endometrial adenocarcinoma.