Objective: To analyze if there are membrane estrogen receptors (ER) in endometrial carcinoma and if there is some relationship between membrane ER and nuclear ER.
Methods: The cell membrane and total cell ERalpha and ERbeta expressions of high and moderate differentiation endometrial carcinoma cells (Ishikawa and HEC-1A cells) were analyzed. Intermittent immunofluorescence dyeing and fluorescent microscopy were carried out with the cells treated with polyformaldehyde and Triton X-100. Intermittent immunofluorescence dyeing and flow cytometry were carried out with the live cells and the cells treated with Triton X-100 respectively.
Results: There were fluorescences on the membrane of the Ishikawa and HEC-1A cells which were treated with polyformaldehyde. When the cells were treated with Triton X-100, the fluorescences were also seen inside the cells. The fluorescence intensity of ERalpha and ERbeta in Ishikawa cell membrane (1.09 +/- 0.21, 1.27 +/- 0.33) was stronger than the control, but there were no significant differences (P > 0.05). When treated with Triton X-100, the total cell fluorescence intensity of ERalpha and ERbeta in Ishikawa cell (4.21 +/- 0.34, 4.69 +/- 1.96) was stronger than the membrane (P < 0.05). The ERalpha and ERbeta fluorescence intensity of HEC-1A cell membrane (1.58 +/- 0.13, 1.49 +/- 0.04) were stronger than the control (P < 0.05). The fluorescence intensity of ERalpha and ERbeta of the HEC-1A cell (2.34 +/- 0.33, 2.52 +/- 0.15) was stronger than the membrane also (P < 0.05). The membrane ERalpha fluorescence intensity of Ishikawa was lower than HEC-1A (P = 0.028). But the total cell ERalpha fluorescence intensity of Ishikawa was higher than HEC-1A (P = 0.002).
Conclusions: There are membrane ER on endometrial carcinoma cells Ishikawa and HEC-1A. The membrane ER must have some similarity to the nuclear receptor. There is no direct correlation between the quantity of the membrane ER and nuclear ER.