Characterization of ERα Signaling to Cell Proliferation Induced by Chronic and Pulsatile E2 Stimulation in 2D and 3D Cell Cultures

Abstract

ABSTRACT17β‐estradiol is a hormone that plays a vital role in human physiology. It acts through estrogen receptors, specifically estrogen receptor α and estrogen receptor β, and its action is determined by the pulsatile secretion in the bloodstream. 17β‐estradiol affects cell proliferation, and dysregulation of 17β‐estradiol:estrogen receptor α signaling contribute to the development of breast cancer. Previous research on 17β‐estradiol:estrogen receptor α signaling has primarily used two‐dimensional cell cultures, which do not fully recapitulate the complexity of tumors that exist in a three‐dimensional environment and do not consider the pulsatile nature of this hormone. To address these limitations, we studied 17β‐estradiol:estrogen receptor α signaling in cell proliferation using both two‐dimensional and three‐dimensional breast cancer cell culture models under continuous and pulsatile stimulation conditions. Results revealed that breast cancer cells grown in an alginate‐based three‐dimensional matrix exhibited similar responsiveness to 17β‐estradiol compared with cells grown in conventional two‐dimensional culture plates. 17β‐estradiol induced the expression of proteins containing estrogen response element in the three‐dimensional model. The efficacy of the antiestrogen drugs fulvestrant (ICI182,280) and 4OH‐tamoxifen was also demonstrated in the three‐dimensional model. These results support the use of the three‐dimensional culture model for studying tumor response to drugs and provide a more realistic microenvironment for such studies. Furthermore, the study revealed that a brief 5‐min exposure to 17β‐estradiol triggered a physiological response comparable with continuous hormone exposure, suggesting that the cellular response to 17β‐estradiol is more important than the continuous presence of the hormone. In conclusion, the study demonstrates that the alginate‐based three‐dimensional culture model is suitable for studying the effects of 17β‐estradiol and antiestrogen drugs on breast cancer cells, offering a more realistic representation of tumor‐microenvironment interactions. The results also highlight the importance of considering the physiological importance of the temporal dynamics in studying 17β‐estradiol signaling and cellular responses.