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 1

RXFP1 is an essential GPCR in OC cell lines.

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RXFP1 is an essential GPCR in OC cell lines. (A) GPCRs identified by sh...
(A) GPCRs identified by shRNA screening. Genes are arranged by number of dependent cell lines based on significance of the normalized zGARP score (<0.05). Other represents clear cell or unknown origin. (B) RXFP1, Pax8, and TP53 staining in OC organoids. Original magnification, ×20. n = 2. (C) Growth of cell lines constitutively expressing shRNA control (shGFP), shRNAs targeting RXFP1 (sh1-RXFP1 or sh2-RXFP1), or targeting PSMD1 (sh-PSMD1). Data points represent mean ± SEM. n = 3. (D) Images of OVCAR8, SKOV3, and OVCAR5 at 72 hours after infection with the indicated constitutively expressed shRNAs. Scale bar: 5 μm. (E) Analysis of apoptosis in OVCAR8 and SKOV3 constitutively expressing shGFP (GFP) or shRNA targeting RXFP1 (sh1 or sh2) 72 hours after infection. (F) Soft agar growth of cells constitutively expressing shGFP or shRNA targeting RXFP1 (sh1 or sh2). Average colony counts are indicated; also see Supplemental Figure 1G. Scale bar: 100 μm. n = 3. (G) Viability of OVCAR8 expressing Dox-inducible TET-shGFP, TET-sh1-RXFP1, or TET-sh-PSMD1 in the absence or presence of Dox (+Dox, 1 μg/mL) compared with untreated cells (UT). Data are represented as mean ± SEM. n = 3. ***P < 0.001, Student’s t test. (H) OVCAR8-derived xenografts expressing Dox-inducible control TET-shGFP or TET-sh1-RXFP1. Dox was initiated on day of cell injection (D0) or 21 days after injection (D21). (I) Analysis of OVCAR8 xenograft tumor measurement. Arrow indicates when Dox treatment was initiated (21 days after injection). Data are represented as mean ± SEM. n = 4. *P < 0.05; ***P < 0.00001, Student’s t test. (J) Final mean volume (± SEM) of tumors described in I. *P < 0.05; ***P < 0.001, Student’s t test.