Identification of a human estrogen receptor α tetrapeptidic fragment with dual antiproliferative and anti-nociceptive action

Abstract

The synthetic peptide ERα17p (sequence: PLMIKRSKKNSLALSLT), which corresponds to the 295–311 region of the human estrogen receptor α (ERα), induces apoptosis in breast cancer cells. In mice and at low doses, it promotes not only the decrease of the size of xenografted triple-negative human breast tumors, but also anti-inflammatory and anti-nociceptive effects. Recently, we have shown that these effects were due to its interaction with the seven-transmembrane G protein-coupled estrogen receptor GPER. Following modeling studies, the C-terminus of this peptide (sequence: NSLALSLT) remains compacted at the entrance of the GPER ligand-binding pocket, whereas its N-terminus (sequence: PLMI) engulfs in the depth of the same pocket. Thus, we have hypothesized that the PLMI motif could support the pharmacological actions of ERα17p. Here, we show that the PLMI peptide is, indeed, responsible for the GPER-dependent antiproliferative and anti-nociceptive effects of ERα17p. By using different biophysical approaches, we demonstrate that the NSLALSLT part of ERα17p is responsible for aggregation. Overall, the tetrapeptide PLMI, which supports the action of the parent peptide ERα17p, should be considered as a hit for the synthesis of new GPER modulators with dual antiproliferative and anti-nociceptive actions. This study highlights also the interest to modulate GPER for the control of pain.

Commentary: harnessing the first peptidic modulator of the estrogen receptor GPER

“…In similar conditions, ERα17p displayed anti-proliferative effects that were rescued by the selective GPER antagonist G-36, suggesting an inverse agonist action ( Lappano et al, 2019 ). In MDA-MB-231 triple negative breast cancer cells, which were engineered to knock out GPER expression by CRISPR/Cas9 genome editing technology, ERα17p failed to show anti-proliferative effects, in contrast to that observed in wild type MDA-MB-231 cells ( Jouffre et al, 2023 ). The abovementioned responses were initiated at the cell membrane ( Kampa et al, 2011 ; Leiber et al, 2015 ; Pelekanou et al, 2011 ; Lappano et al, 2019 ).…”

“…In addition to these antitumor actions, the peptide ERα17p has demonstrated GPER-dependent anti-nociceptive effects at the supraspinal level and anti-inflammatory activities, from 2.5 mg/kg, in inflammation animal models ( Mallet et al, 2021 ; Jouffre et al, 2023 ).…”

Promising Perspectives of the Antiproliferative GPER Inverse Agonist ERα17p in Breast Cancer

“…Ca 2+ -calmodulin [16] Direct partners of the 295-311 region of ERα (in the context of the peptide ERα17p) Ca 2+ -calmodulin [16,24,25,31] ERα17p, to form amyloid fibrils, hydrogels and complex aggregates [30,32,33] Estrogen receptor α [21] GPER [28] Heat Shock Protein 70 (HSP70) [26] Hard and soft negative lipid-containing surfaces including cell membrane models [29,33,34] In the light of previous results, we have explored the ability of ERα17p to bind cell membranes. An interaction was evidenced by confocal imaging microscopy and a FACS analysis by using an FITC-labeled version of ERα17p, in both ERα-positive and -negative breast cancer cells, suggesting an ERα-independent process [35].…”

“…Strikingly, experimental results have shown recently that the PLMI peptide, which corresponds to the N-terminus of ERα17p, was sufficient to closely mimic the anti-proliferative effects of the whole peptide [28,32]. This motif has also been claimed to direct the interaction between ERα17p and Ca 2+ -CaM [37] and to present the considerable advantage of not being amyloidogenic, in contrast with ERα17p, which exhibits a primary amphipathic character [32,33].…”

“…• ERα17p and GPER co-localize at the cytoplasmic membrane, as shown by using fluorescence microscopy, a fluorescent version of ERα17p and the anti-GPER antibody TA35133 [28]; • A GPER siRNA abrogates ERα17p's effects [37]; • ERα17p is inactive in a GPER knockout (KO) cellular model obtained by CRISPR/Cas9 [32].…”