Notch-1 Signaling Activation and Progesterone Receptor Expression in Ectopic Lesions of Women With Endometriosis

Abstract

ContextProgesterone (P) resistance is a hallmark of endometriosis, but the underlying mechanism(s) for loss of P sensitivity leading to lesion establishment remains poorly understood.ObjectiveTo evaluate the association between Notch-1 signaling activation and P resistance in the progression of endometriosis.DesignCase control study; archived formalin-fixed, paraffin-embedded tissues.SettingUniversity hospitals (United States, Taiwan).PatientsWomen with endometriosis; human endometrial stromal cell line (HESC).InterventionEutopic endometria (EU) and ectopic lesions (ECs) were collected from surgically diagnosed patients. Archived tissue sections of EU and ECs were identified. HESCs were treated with N-[N-(3,5-difluorophenacetyl)-l-alanyl]-S-phenylglycine t-butyl ester (DAPT) and valproic acid (VPA) to, respectively, suppress and induce Notch-1 activation.Outcome MeasuresTissues were analyzed for Notch Intra-Cellular Domain 1 (NICD1) and progesterone receptor (PGR) protein expression by immunohistochemistry and for transcript levels of NICD1 target genes HES1, PGR, and PGR-B by quantitative reverse transcription polymerase chain reaction. DAPT- or VPA-treated HESCs with and without P cotreatment were evaluated for cell numbers and for PGR, HES1, and PGR target gene DKK1 transcript levels.ResultsNuclear-localized stromal NICD1 protein levels were inversely associated with those of total PGR in EU and ECs. Stromal ECs displayed higher HES1 and lower total PGR and PGR-B transcript levels than EU. In HESCs, DAPT reduction of NICD1 decreased cell numbers and increased PGR transcript and nuclear PGR protein levels and, with P cotreatment, maintained P sensitivity. Conversely, VPA induction of NICD1 decreased PGR transcript levels and, with P cotreatment, abrogated P-induced DKK1 and maintained HES1 transcript levels.ConclusionsAberrant Notch-1 activation is associated with decreased PGR that contributes to P resistance in endometriosis.

γ‐Secretase inhibition affects viability, apoptosis, and the stem cell phenotype of endometriotic cells

“…Previous studies on endometrial and endometriotic stroma cells employing the GSI DAPT had demonstrated reduced generation and nuclear localization of the intracellular domain of notch, respectively . The application of an unbiased screening approach has produced a second important outcome of our study, as it revealed an impact of GSI on stemness‐related genes other than notch.…”

“…Although short‐term treatments resulted in moderate effects, our colony formation assays indicate that prolongation of the treatment substantially enhances treatment efficacy. A decrease in cell proliferation was recently also observed in an endometrial stroma cell line upon treatment with a different GSI, DAPT, indicating that γ‐secretase inhibition affects both the epithelial and stromal compartments of the endometrium . Decreased proliferation would be in line with a reduction in stem cell‐like properties, as stem cells exhibit an unlimited proliferative potential …”

“…Their intracellular domain is proteolytically released upon binding of the integral membrane ligands of the Delta Serrate Lag‐2 family (DLL‐1,‐3,‐4 and Jagged‐1 and ‐2). In association with accessory proteins, this domain can act as a transcription factor driving the expression of stemness‐related genes, consisting of the transcription factor Hes‐1 and the transcriptional repressor Hey‐1 . Numb antagonizes notch signaling by posttranscriptional regulation of Notch, which itself is regulated by Msi1 .…”

“…8 However, in contrast to this, a study by the Fazleabas group found decreased notch signaling in the eutopic endometrium of women with endometriosis, resulting in impaired decidualization. 9 Notch activation was linked to progesterone resistance in endometriotic lesions, 10 and to angiogenesis in a mouse model. 11 The notch family consists of 4 transmembrane proteins, which share distinct sequence similarity with epidermal growth factor-1 receptors.…”

“…In association with accessory proteins, this domain can act as a transcription factor driving the expression of stemness-related genes, consisting of the transcription factor Hes-1 and the transcriptional repressor Hey-1. [6][7][8][9][10][11] Numb antagonizes notch signaling by posttranscriptional regulation of Notch, which itself is regulated by Msi1. 7,8,12 Proteolytic cleavage by γ-secretase is a key step in Notch activation, and γ-secretase inhibitors (GSIs) have already entered clinical trials in the context of neurogenerative and malignant diseases.…”