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 3

Expression of relaxin in OC cell lines is essential for survival.

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Expression of relaxin in OC cell lines is essential for survival. (A) Sc...
(A) Schematic of relaxin signaling via RXFP receptors (RXFP1, RXFP2, RXFP3) and ligands (RLN1/RLN2/RLN3/INSL3) summarizing ligand specificity, relative potency, and reported cross reactivity. (B) mRNA levels of RLN1 and RLN2 in OVCAR8, SKOV3, and PEA2. For panels B and C, box plots indicate the IQR of the data, and the central line shows the median. ***P < 0.001; ****P < 0.0001, Student’s t test. (C) Relaxin levels in media derived from OVCAR8 and SKOV3 constitutively expressing shGFP or shRNA targeting RLN (sh1- or sh2-RLN) 120 hours following selection. n = 3. ***P < 0.001, Student’s t test. (D) Analysis of prorelaxin- and apoptosis-related factors in OVCAR8 and SKOV3 constitutively expressing shGFP or shRNA targeting RLN (sh1- or sh2-) 48 hours following selection. cl-PARP, cleaved PARA; cl-CASP3, cleaved caspase-3. (E) Growth of OC cell lines constitutively expressing shGFP or shRNA targeting RLN. Data are represented as mean ± SEM. n = 3. (F) Soft agar growth of cell lines expressing shGFP or shRNA targeting RLN. Average colony counts are indicated; also see Supplemental Figure 3G. Scale bar: 100 μm. n = 3. (G) Tumors derived from OVCAR8 expressing shGFP or sh1-RLN. (H) Growth curves of tumors described in G. *P < 0.02, Student’s t test. (I) Representative images of CD31 IHC in shGFP control and sh1-RLN–expressing tumors. Scale bar: 10 μm. (J) Quantification of MVD (CD31-positive clusters per unit area) in CD31-enriched regions within tumors expressing shGFP (n = 11 regions) or sh1-RLN (n = 9 regions). Box plots indicate the IQR of the data, and the central line shows the median. ***P < 0.0001, Student’s t test.