Genomic and nongenomic effects of estrogen signaling in human endometrial cells: Involvement of the growth factor receptor signaling downstream AKT pathway

For the endometrium, estradiol and tamoxifen induce proliferation, and consequently, tamoxifen treatment of breast cancer results in a 2-fold to 7-fold increased risk for endometrial cancer. Here, the role of activation of growth factor receptor signaling in mediating the e fects of estrogen and tamoxifen is determined. Microarray analysis of ECC-1 cells treated with estradiol or tamoxifen indicate that rapid responses to treatment (1 hour) are very distinct from long-term responses (>24 hours). Furthermore, estradiol and tamoxifen are observed to induce AKT activation. Comparing long-term estrogen- and tamoxifen-regulated genes with genes regulated by insulin-like growth factor 1 and amphiregulin reveals that the late e fects of estrogen and tamoxifen signaling may partly be mediated via activation of growth factor receptor signaling pathways. It is hypothesized that both early and late e fects of estrogen and tamoxifen signaling in the endometrium are partly mediated via the activation of growth factor receptor signaling, putatively at the level of AKT activation.

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