Enhancing Progestin Therapy with a Glucagon-Like Peptide 1 Agonist for the Conservative Management of Endometrial Cancer

Abstract

Objective: Obesity is a major risk factor for endometrial cancer. In addition to hormone therapy with progestins, glucagon like peptide-1 receptor (GLP-1R) agonists such as semaglutide may be helpful to achieve weight loss during conservative treatment of endometrial hyperplasia or cancer.

Methods: We theorized that the combination of semaglutide and the progestin levonorgestrel would be useful as a novel treatment or prevention regimen and tested this hypothesis using endometrial cancer cell lines and patient-derived organoids (PDOs).

Results: Hec50, KLE, and Ishikawa endometrial cancer cells express GLP-1R, as determined by both qPCR and Western blotting, and GLP-1R agonist treatment induces GLP-1R mRNA transcription through positive feedback mechanisms in cell models. PDOs from six individuals with grade 1 endometrial carcinomas were treated with progesterone, levonorgestrel, semaglutide, or levonorgestrel + semaglutide. Multiple models demonstrated a significant reduction in viability in response to combinatorial treatment, and the effect was noted in models from both PR high- and PR low-expressing tumors. Most interesting was the induction not only of the membrane GLP-1R with treatment, but also the significant upregulation of nuclear and membrane progesterone receptors-PR and PGRMC1/2, respectively-indicating a potential positive feedback loop between semaglutide and progestins such as levonorgestrel.

Conclusion: In summary, we identify synergistic molecular cross-talk between the GLP-1R and steroid hormone receptor pathways, with the potential to enhance the anticancer activity of levonorgestrel when combined with semaglutide.

Keywords: conservative management; endometrial cancer; glucagon-like peptide 1 receptor agonists; hormone therapy; progesterone.

Figure 1

GLP-1Rs are expressed in endometrial cancer cells, and transcription is induced in response to GLP-1R agonist treatment. (A): Western blotting confirms protein expression of GLP-1R in multiple endometrial cancer cell lines. Expression was determined by densitometry and calculated relative to Ishikawa cells after normalization to the β-actin loading control. (B): qPCR for GLP receptor transcripts in Ishikawa endometrial cancer cells demonstrates expression, as well as significant upregulation of this gene in response to agonists liraglutide and semaglutide at 24 and 48 h after treatment. * p ≤ 0.05; *** p ≤ 0.001 vs. untreated control at the same timepoint.

Figure 2

qPCR for the following mRNAs: GLP-1R, PGRMC1, PGRMC2, FOXO1, ER, AR, GR, MR, and PR following treatment of Ishikawa cells for 12, 24, and 48 h with semaglutide (blue line), levonorgestrel (orange line), or semaglutide + levonorgestrel (gray line). Fold change in expression was calculated relative to time-matched controls (DMSO vehicle) after correcting for housekeeping gene (18S rRNA) expression using the ∆∆Ct method. * p < 0.05; ** p < 0.01 vs. time-matched control by t-test.

Figure 3

Heterogeneity in expression of estrogen receptor (ER) and progesterone receptor (PR) in early-stage/grade endometrial tumors. All images are at 20× magnification. The modified H-score for each specimen is noted below each image.

Figure 4

Semaglutide + levonorgestrel inhibits the growth of endometrial cancer patient-derived organoids (PDOs). PDOs from Grade 1 endometrial carcinomas were treated with progesterone (P4), levonorgestrel (L), semaglutide (S), or L+S. All drug concentrations are 100 nM. Cells were treated for 72 h. PR expression was determined by IHC of the primary tumor specimens from which the PDOs were generated (see Figure 3); models are arranged in order of highest to lowest PR expression. Control: vehicle (DMSO). * p < 0.05, ** p < 0.01, *** p < 0.001, or **** p < 0.0001 by one-way ANOVA.

Figure 5

A proposed mechanism of cooperation between GLP-1R agonists and progestins. GLP-1R agonists and progestins bind to membrane receptors, including the 7-transmembrane GLP-1R and PGRMC1. It is proposed that PGRMC1 enhances the activation of GLP-1R, which signals downstream through C-Src and ERK to phosphorylate and activate PRB. That phosphorylation event induces PRB translocation to the nucleus and ligand binding, allowing activated PRB and PRA to enhance progestin-dependent gene regulation and endometrial differentiation. Activated GLP-1R also enhances cAMP effects, inducing insulin exocytosis. Red arrows denote key factors that are increased at the mRNA level by the combination of semaglutide and levonorgestrel in this study.