Inhibition of relaxin autocrine signaling confers therapeutic vulnerability in ovarian cancer
Helen E. Burston, … , Anne-Marie Mes-Masson, Robert Rottapel
Helen E. Burston, … , Anne-Marie Mes-Masson, Robert Rottapel
Published February 9, 2021
Citation Information: J Clin Invest. 2021;131(7):e142677. https://doi.org/10.1172/JCI142677.
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Research Article Oncology

Inhibition of relaxin autocrine signaling confers therapeutic vulnerability in ovarian cancer

Abstract

Ovarian cancer (OC) is the most deadly gynecological malignancy, with unmet clinical need for new therapeutic approaches. The relaxin peptide is a pleiotropic hormone with reproductive functions in the ovary. Relaxin induces cell growth in several types of cancer, but the role of relaxin in OC is poorly understood. Here, using cell lines and xenograft models, we demonstrate that relaxin and its associated GPCR RXFP1 form an autocrine signaling loop essential for OC in vivo tumorigenesis, cell proliferation, and viability. We determined that relaxin signaling activates expression of prooncogenic pathways, including RHO, MAPK, Wnt, and Notch. We found that relaxin is detectable in patient-derived OC tumors, ascites, and serum. Further, inflammatory cytokines IL-6 and TNF-α activated transcription of relaxin via recruitment of STAT3 and NF-κB to the proximal promoter, initiating an autocrine feedback loop that potentiated expression. Inhibition of RXFP1 or relaxin increased cisplatin sensitivity of OC cell lines and abrogated in vivo tumor formation. Finally, we demonstrate that a relaxin-neutralizing antibody reduced OC cell viability and sensitized cells to cisplatin. Collectively, these data identify the relaxin/RXFP1 autocrine loop as a therapeutic vulnerability in OC.

Authors

Helen E. Burston, Oliver A. Kent, Laudine Communal, Molly L. Udaskin, Ren X. Sun, Kevin R. Brown, Euihye Jung, Kyle E. Francis, Jose La Rose, Joshua Lowitz, Ronny Drapkin, Anne-Marie Mes-Masson, Robert Rottapel

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Figure 2

Relaxin initiates signaling pathways and gene activation.

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Relaxin initiates signaling pathways and gene activation. (A) Cell viabi...
(A) Cell viability in the absence (untreated [UT]) or presence of recombinant human RLN2 (+Relaxin, 50 ng/mL) for 24 hours. Results represent absorbance unit (AU) measurements (n = 5). Data are represented as mean ± SEM. *P < 0.05; **P < 0.01, Student’s t test. (B) BrdU incorporation in OVCAR8 in the absence (untreated) or presence of recombinant RLN2 (+Relaxin, 50 ng/mL) following transfection with control siRNA (siCON) or 2 different siRNAs targeting RXFP1 (si1-RXFP1 and si2-RXFP1). Results represent absorbance unit measurements. n = 3. Data are represented as mean ± SEM. (C) Analysis of p-MEK and p-AKT in OVCAR8 treated with human RLN2 (50 ng/mL) following transfection with siRNA control (siCON) or si-RXFP1. (D) Significantly enriched pathways identified by RNA-Seq (FDR Q value <0.01) in RLN2-treated OVCAR8. Nodes represent enriched pathways and edges the number of genes overlapping between 2 pathways. Enrichment analysis was carried out using g-profiler and visualized using Cytoscape. (E) QPCR analysis of the indicated mRNA transcripts in untreated cells or cells treated with RLN2 (+R, 50 ng/mL for 8 hours). Data points represent individual wells/replicates. Box plots indicate the interquartile range (IQR) of the data, and the central line shows the median. n ≥ 5.